JP2006066908A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of variations that occur in particular between a plurality of thin film transistors electrically connected in parallel, the variations being caused by bumps and dips called ridges that are formed on the surface of a semiconductor when a semiconductor film is irradiated with laser beams by conventional pulsed oscillation and which significantly affect the device characteristics of a top-gate type TFT. <P>SOLUTION: One of the features of a manufacture of a circuit consisting of a plurality of thin films is the arrangement of an active layer of a plurality of thin film transistors (thin film transistors electrically connected in parallel) in one of the regions with an increase in the width LP of the region (not including microcrystal regions) that melts by irradiating a semiconductor film with laser beams using a continuous-wave laser. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor device having a circuit formed of a thin film transistor (hereinafter referred to as TFT) and a manufacturing method thereof. For example, the present invention relates to an electronic apparatus in which an electro-optical device typified by a liquid crystal display panel or a light-emitting display device having an organic light-emitting element is mounted as a component.

  Note that in this specification, a semiconductor device refers to all devices that can function by utilizing semiconductor characteristics, and an electro-optical device, a semiconductor circuit, and an electronic device are all semiconductor devices.

  In recent years, a technique for forming a thin film transistor (TFT) using a semiconductor thin film (having a thickness of about several to several hundred nm) formed on a substrate having an insulating surface has attracted attention. Thin film transistors are widely applied to electronic devices such as ICs and electro-optical devices, and development of switching devices for image display devices is urgently required.

  In particular, a thin film transistor using a polycrystalline semiconductor film has a mobility two or more digits higher than that of a TFT using an amorphous semiconductor film, and the pixel portion of a semiconductor display device and its peripheral drive circuit are integrated on the same substrate. It has the advantage that it can be formed. The polycrystalline semiconductor film can be formed over an inexpensive glass substrate by using a laser annealing method.

Lasers used for laser annealing are roughly classified into two types, pulse oscillation and continuous oscillation, depending on the oscillation method. A pulsed laser typified by an excimer laser has a laser beam energy output per unit time of about 3 to 6 digits higher than that of a continuous wave laser. Therefore, the beam spot (irradiation area where the laser beam is actually irradiated on the surface of the object to be processed) is shaped by an optical system so as to be a rectangular shape of several centimeters square or a linear shape having a length of 100 mm or more. By efficiently irradiating the film with laser light, the throughput can be increased. For this reason, it has become the mainstream to use a pulsed laser for crystallization of the semiconductor film.

  Here, “linear” does not mean “line” in a strict sense, but means a rectangle (or oval) having a large aspect ratio. For example, an aspect ratio of 2 or more (preferably 10 to 10000) is called a linear shape, but the linear shape is still included in a rectangular shape.

Patent Document 1 discloses a technique in which a pulse oscillation laser is used, and two channel regions CH in which the total channel width is the operation design value W are set such that the total value of W and the separation distance WA is larger than the pitch P of the pulse laser. Is described.
Japanese Patent No. 3276900

An excimer laser is widely used as a pulsed laser. However, it is difficult for the excimer laser to extremely increase the cross-sectional area of a laser beam (hereinafter also referred to as laser light) because of the output power. Accordingly, the entire surface of the substrate is irradiated by shaping the laser beam into a strip shape or a line shape and scanning the laser beam while overlapping it. During this scanning, the crystal grain size becomes non-uniform due to the influence of the energy distribution of the laser beam.

  A semiconductor film crystallized using pulsed laser light is formed of a collection of a plurality of crystal grains whose positions and sizes are random. Compared with the inside of a crystal grain, the interface (crystal grain boundary) of a crystal grain has innumerable recombination centers and trap centers due to an amorphous structure or crystal defects. When carriers are trapped in this trapping center, the grain boundary potential rises and becomes a barrier against the carriers, so that there is a problem that the carrier transport property is lowered.

  When the semiconductor film is irradiated with pulsed laser light, the semiconductor film is instantaneously melted from the surface, and then the molten semiconductor film is cooled and solidified from the substrate side for heat conduction to the substrate. In this solidification process, it is recrystallized to become a semiconductor film having a crystal structure with a large grain size. However, since it is once melted, volume expansion occurs and irregularities called ridges are formed on the semiconductor surface. Since the surface having a ridge is a surface in contact with the gate insulating film, the device characteristics are greatly influenced by the ridge.

  Due to the above-described factors, there is a problem that the operation characteristics of driving thin film transistors integrated in a display device or the like are varied and display unevenness occurs. In particular, variation between a plurality of thin film transistors electrically connected in parallel is a problem. Similarly, when a CPU or the like in which a circuit having thin film transistors is integrated is manufactured, there is a problem that the operation characteristics of the thin film transistors are varied and it is difficult to perform a uniform operation.

  Thus, in recent years, a technique related to crystallization of a semiconductor film using a continuous wave laser has attracted attention. In the case of a continuous wave laser, unlike a conventional pulsed laser, a semiconductor film is irradiated with laser light while scanning in one direction, and a crystal is continuously grown in the scanning direction. A collection of crystal grains made of a single crystal extending along the length can be formed. Therefore, irregularities called ridges are not formed. By using the above method, it is considered that a semiconductor film can be formed in which there is almost no crystal grain boundary intersecting at least the channel direction of the TFT.

  In manufacturing a circuit including a plurality of thin film transistors, the present invention increases a width LP (excluding a microcrystalline region) of a region that is melted by irradiating a semiconductor film with laser light using a continuous wave laser, One feature is that an active layer of a plurality of thin film transistors (thin film transistors connected in parallel) is arranged.

As a circuit formed of a plurality of thin film transistors, typically, a CMOS circuit, an NMOS circuit, a PMOS circuit, and the like can be given. Inverter circuit, NAND circuit, AND circuit, NOR circuit, OR circuit, shift register circuit, sampling circuit, D / A converter circuit, A / D converter circuit, latch circuit, buffer using CMOS circuit, NMOS circuit, or PMOS circuit A circuit or the like can be manufactured. In addition, a memory element such as SRAM and DRAM and other elements can be configured by combining these circuits.

  When a semiconductor film is irradiated with laser light using a continuous wave laser, a microcrystalline region with a small grain size is formed between an irradiated region and an unirradiated region. This microcrystalline region is formed on both sides of a crystalline region where a relatively large crystal is formed. In addition, when laser light is irradiated on the entire surface of the semiconductor film, it is preferable to repeat scanning of the laser light so that the microcrystalline regions overlap.

  In this specification, the pitch refers to the width of the irradiation region including one microcrystalline region. In addition, the laser beam width LP indicates an irradiation region width that does not include a microcrystalline region, that is, a distance between adjacent microcrystalline regions (a width of a crystal region in which a relatively large crystal is formed). The full width of the laser beam indicates the width of the irradiation region including both microcrystalline regions, that is, the full width of the laser beam shape on the irradiation surface.

The configuration of the invention disclosed in this specification is as follows.
A semiconductor having a plurality of thin film transistors having an active layer formed by forming a semiconductor thin film on a substrate having an insulating surface, irradiating a laser beam of a continuous wave laser, melting and cooling the semiconductor thin film, and recrystallization. Device,
The plurality of thin film transistors are electrically connected in parallel,
The total sum (WC + WS) of the channel formation region widths WC of the plurality of thin film transistors and the interval WS between the channel formation regions is smaller than the laser beam width LP of the continuous wave laser. Device.

In the case where at least two thin film transistors are arranged in parallel, another configuration of the invention is that a semiconductor thin film is formed on a substrate having an insulating surface, and the semiconductor thin film is melted and cooled by irradiation with a laser beam of a continuous wave laser. A semiconductor device having a plurality of thin film transistors using the semiconductor thin film as an active layer.
Among the plurality of thin film transistors, at least two thin film transistors are electrically connected in parallel,
A channel formation region width W1 of the first thin film transistor;
An interval W2 between the channel formation region of the first thin film transistor and the channel formation region of the second thin film transistor disposed adjacent to the first thin film transistor;
The total sum (W1 + W2 + W3) of the channel formation region width W3 of the second thin film transistor is smaller than the laser beam width LP of the continuous wave laser.

  Further, instead of a continuous-wave laser (CW), laser light (also referred to as a pseudo CW laser) emitted from a pulse laser oscillator having a frequency of 10 MHz or more can be used. A frequency band that is significantly higher than the frequency band of several tens to several hundreds of Hz used in conventional pulsed lasers is used. It is said that the time from when the semiconductor film is irradiated with laser light by pulse oscillation until the semiconductor film is completely solidified is several tens of nanoseconds to several hundreds of nanoseconds. When a pulse laser oscillator of 10 MHz or more is used, the semiconductor film The laser light of the next pulse can be irradiated after being melted by the laser light and solidifying.

  Unlike the case of using a conventional pulsed laser, the solid-liquid interface can be continuously moved in the semiconductor film, so that a semiconductor film having crystal grains continuously grown in the scanning direction is formed. . Specifically, the crystal grains included in the scanning direction have a width in the scanning direction of 10 to 30 μm, preferably 10 to 60 μm, and a set of crystal grains having a width in the direction perpendicular to the scanning direction of about 1 to 5 μm is formed. Can do.

  In addition, the pseudo CW laser can dramatically increase the area of the beam spot as compared with a continuous wave laser, can suppress thermal damage to the glass substrate, and can continuously crystallize in the scanning direction. It is possible to grow and form a collection of crystal grains composed of a single crystal extending long along the scanning direction.

In addition, the configuration of other inventions is as follows:
A semiconductor thin film is formed on a substrate having an insulating surface, and a laser beam of a pulsed laser having a frequency of 10 MHz to 100 GHz is irradiated to melt and cool the semiconductor thin film to recrystallize the semiconductor thin film. A semiconductor device having a plurality of thin film transistors,
The plurality of thin film transistors are electrically connected in parallel, and a total (WC + WS) of the total width WC of the channel formation regions of the plurality of thin film transistors and the interval WS between the channel formation regions is the pulse oscillation. It is a semiconductor device characterized by being smaller than the laser beam width LP of the laser.

In addition, the configuration of other inventions is as follows:
A semiconductor thin film is formed on a substrate having an insulating surface, and a laser beam of a pulsed laser having a frequency of 10 MHz to 100 GHz is irradiated to melt and cool the semiconductor thin film to recrystallize the semiconductor thin film. A semiconductor device having a plurality of thin film transistors,
Among the plurality of thin film transistors, at least two thin film transistors are electrically connected in parallel,
A channel formation region width W1 of the first thin film transistor;
An interval W2 between the channel formation region of the first thin film transistor and the channel formation region of the second thin film transistor disposed adjacent to the first thin film transistor;
The semiconductor device is characterized in that a total (W1 + W2 + W3) of the channel formation region width W3 of the second thin film transistor is smaller than the laser beam width LP of the pulsed laser.

  In each of the above structures, one of the characteristics is that the plurality of thin film transistors are arranged at equal intervals.

The CW laser oscillator used in the present invention is not particularly limited, and a YAG laser, a YVO ₄ laser, a GdVO ₄ laser, a YLF laser, and an Ar laser can be used.

The pseudo CW laser can be any laser that can oscillate an extremely short pulse laser beam having a pulse width of 20 psec or less. For example, an excimer laser, an Ar laser, a Kr laser, a CO ₂ laser, A YAG laser, Y ₂ O ₃ laser, YVO ₄ laser, YLF laser, YAlO ₃ laser, glass laser, ruby laser, alexandrite laser, Ti: sapphire laser, copper vapor laser, gold vapor laser, or the like can be used.

In addition, a method for manufacturing a semiconductor device for obtaining each of the above structures is also one aspect of the present invention.
A semiconductor film is formed over the insulating surface, a laser beam for crystallizing the semiconductor film is scanned with respect to the semiconductor film, and the semiconductor film is selectively etched to form the first semiconductor layer and the second semiconductor layer. Forming a first thin film transistor having a first semiconductor layer having a first channel formation region and forming a second thin film transistor having a second semiconductor layer having a second channel formation region A method of making the device,
The sum (WC + WS) of the total width WC of the channel formation regions of the first thin film transistor and the second thin film transistor and the interval WS between the channel formation regions is smaller than the laser beam width LP of the laser light. This is a method for manufacturing a semiconductor device.

  In the structure related to the above manufacturing method, the laser beam is one of features of a continuous wave laser beam or a pulsed laser beam having a frequency of 10 MHz to 100 GHz.

  In the structure related to the above manufacturing method, the semiconductor film may be preliminarily crystallized by heat treatment and then irradiated with a laser beam. Before the laser beam is scanned onto the semiconductor film, the semiconductor film is heated to be crystallized. One of the features is to have a process of causing

In the structure related to the manufacturing method, one of the features is that the width direction of the first channel formation region and the width direction of the second channel formation region are perpendicular to the scanning direction of the laser beam. .

  In the structure related to the above manufacturing method, the first thin film transistor and the second thin film transistor are electrically connected in parallel.

  When a crystalline semiconductor film is manufactured by using the method for manufacturing a crystalline semiconductor film of the present invention, an irradiated object can be crystallized uniformly, so that a crystalline semiconductor film with good characteristics can be obtained with high throughput. It becomes possible. Further, variation in characteristics between elements manufactured using the crystalline semiconductor film crystallized by using the method for manufacturing a crystalline semiconductor film of the present invention can be reduced.

  Embodiments of the present invention will be described below. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention should not be construed as being limited to the description of the embodiment modes.

(Embodiment 1)
A state in which a surface of a semiconductor film provided over a substrate is scanned with a CW laser beam and a manufactured TFT will be described with reference to FIGS.

  FIG. 1A shows a top view of a state in which a laser beam 11 is scanned on the surface of an amorphous semiconductor film. A laser beam 11 having a long elliptical spot is scanned in a scanning direction 12 indicated by an arrow in the drawing to partially form a crystal region.

  Note that although not illustrated in FIG. 1A, an example in which a top-gate TFT is manufactured, a base insulating film is provided over a substrate having an insulating surface, and an amorphous semiconductor is formed thereover. A film is formed.

In crystallization of an amorphous semiconductor film, a solid-state laser capable of continuous oscillation is used in this embodiment, and the second harmonic, third harmonic, or fourth harmonic of the fundamental wave is used. Can be obtained. Typically, it is desirable to use the second harmonic (532 nm) or the third harmonic (355 nm) of an Nd: YVO ₄ laser (fundamental wave 1064 nm). Specifically, laser light emitted from a continuous wave YVO ₄ laser is converted into a harmonic by a non-linear optical element to obtain laser light with an output of 10 W. As an example of the form of the resonator, there is one in which a YVO ₄ crystal and a non-linear optical element are put in the resonator and a harmonic is emitted. Then, it is preferably formed into a rectangular or elliptical laser beam on the irradiation surface by an optical system, and irradiated to the object to be processed. In this case, a power density of about 0.01 to 100 MW / cm ² (preferably 0.1 to 10 MW / cm ²⁾ is required.

  The scanning of the laser beam is an irradiation system moving type in which the substrate that is the object to be processed is fixed and the irradiation position of the laser beam is moved, an object moving type in which the laser light irradiation position is fixed and the substrate is moved, Alternatively, a method combining the above two methods can be used. In any case, it is premised that the relative movement direction of each laser beam spot with respect to the semiconductor film can be controlled. In this embodiment mode, irradiation is performed by moving the amorphous semiconductor film relative to the laser light at a speed of about 10 to 2000 cm / sec. In addition, when waviness exists in the substrate, it is preferable to operate the autofocus mechanism in accordance with the waviness and perform laser light irradiation.

  The irradiated region 14a in which crystal grains that have been irradiated with laser light and grown in the scanning direction are formed has excellent crystallinity. Therefore, extremely high mobility and on-state current can be expected by using this region as a channel formation region of the TFT.

  As shown in FIG. 1A, it is preferable to design so that a region 15a to be a channel of a TFT to be formed later is positioned inside the irradiation region 14a. In particular, when two TFTs are electrically connected in parallel as shown in the top view of FIG. 1B, the region serving as the channel of both TFTs is set to be inside the irradiation region 14a. In FIG. 1B, two TFTs are arranged side by side in a direction perpendicular to the scanning direction. That is, the width LP of the irradiation region 14a is made larger than the sum (W1 + W2 + W3) of the channel width W1 of the first TFT, the channel width W3 of the second TFT, and the channel spacing W2. This is one of the features of the invention.

  In addition, an irradiation region 14b that becomes a microcrystal is formed in a region between the irradiation region 14a and the non-irradiation region 13. Since it is not preferable that the irradiation region 14b serving as the microcrystal is part of the active layer of the TFT, it is not overlapped with the region 15b serving as the active layer. Further, in the case of performing repeated irradiation, scanning is performed so that the irradiation regions 14b that are microcrystals overlap each other. That is, the portions of the irradiation region 14b that become microcrystals are overlapped.

  When the laser beam irradiation is finished, patterning is performed to form two island-shaped semiconductor layers, and a gate insulating film, a gate electrode, an interlayer insulating film, a source wiring, a drain wiring, and the like are formed using a known technique. A thin film transistor is completed.

  FIG. 1B shows how the two completed TFTs are connected. Although FIG. 1B is shown corresponding to FIG. 1A, in reality, shrinkage of the substrate or the like is generated by heat treatment or the like during the TFT manufacturing process, and the size of the active layer is reduced.

In FIG. 1B, a first semiconductor layer 16a and a second semiconductor layer 16b are arranged in parallel. The two TFTs have a common gate wiring 17, source wiring 18, and drain wiring 19, and are electrically connected in parallel.

1C is a cross-sectional view taken along the solid line A-A ′ in FIG. The following is a simplified procedure for manufacturing a typical TFT using the present invention.

In FIG. 1C, a glass substrate, a quartz substrate, or the like can be used as the substrate 20. Alternatively, a plastic substrate having heat resistance that can withstand the processing temperature in this step may be used.

First, as shown in FIG. 1C, a base insulating film made of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiO _x N _y ) is formed on the substrate 20. A typical example is a two-layer structure as a base insulating film, and a silicon nitride oxide film 21a formed by using SiH ₄ , NH ₃ , and N ₂ O as a reaction gas is 50 to 100 nm, SiH ₄ , and N _2. A structure in which a silicon oxynitride film 21b formed using O as a reactive gas is continuously formed to a thickness of 100 to 150 nm and stacked is employed. Further, it is preferable to use a silicon nitride film (SiN film) or a silicon oxynitride film (SiN _x O _y film (X> Y)) having a thickness of 10 nm or less as one layer of the base insulating film. Alternatively, a three-layer structure in which a silicon nitride oxide film, a silicon oxynitride film, and a silicon nitride film are sequentially stacked may be used.

  Next, a semiconductor film having an amorphous structure is formed over the base insulating film. A semiconductor material containing silicon as a main component is used for the semiconductor film. Typically, an amorphous silicon film, an amorphous silicon germanium film, or the like is formed by a known means (a sputtering method, an LPCVD method, a plasma CVD method, or the like). Then, a semiconductor film having a crystal structure is obtained by the above-described CW laser.

  Next, patterning is performed using a photolithography technique to obtain a first semiconductor layer and a second semiconductor layer. Before forming a resist mask in patterning, ozone is generated by UV irradiation in an aqueous solution containing ozone or in an oxygen atmosphere to form an oxide film in order to protect each semiconductor layer. The oxide film here also has the effect of improving the wettability of the resist.

  If necessary, a small amount of impurity element (boron or phosphorus) is doped through the oxide film in order to control the threshold value of the TFT before patterning. When doping is performed through the oxide film, the oxide film is removed, and an oxide film is formed again with an aqueous solution containing ozone.

Next, an insulating film containing silicon as a main component and serving as a gate insulating film is formed so as to cover the surface of each semiconductor layer. As the gate insulating film, a silicon oxide film or a silicon oxynitride film by a PCVD method is used, and the film thickness is 10 nm to 100 nm, preferably 10 nm to 30 nm, and relatively thin. By reducing the thickness of the gate insulating film, the circuit including the TFT can be driven at higher speed. Here, a gate insulating film having a stacked structure of a first insulating film 24a made of a silicon oxide film and a second insulating film 24b made of a silicon nitride oxide film is formed. Note that the oxide film may be removed with an etchant containing hydrofluoric acid before the gate insulating film is formed. Further, it is not particularly necessary to completely remove the oxide film of the semiconductor layer, and the oxide film may be left thin. If the semiconductor layer is exposed by overetching, the surface may be contaminated with impurities.

Next, after cleaning the surface of the gate insulating film, a metal film (an element selected from Mo, Ta, W, Ti, Al, Cu, or an alloy material or compound material containing the element as a main component by sputtering is used. Layer, or a stack of these).

  Next, the metal wiring is patterned using a photolithography technique to form the gate wiring 17.

  Next, an impurity element imparting n-type (P, As, etc.) or an impurity element imparting p-type (B, etc.) is added as appropriate to each semiconductor layer to form the source region 22 and the drain region 23. The semiconductor layer is added through the gate insulating film by ion doping or ion implantation. When an n-channel TFT is formed, an impurity region imparting n-type conductivity may be added to form an impurity region. When a p-channel TFT is formed, an impurity element imparting p-type is added. Thus, an impurity region may be formed.

  In the subsequent steps, an interlayer insulating film 25 is formed, hydrogenation is performed, contact holes reaching the source region 22 and the drain region 23 are formed, a conductive film is formed and patterned, and the source electrode 18 and the drain are formed. An electrode 19 is formed to complete the TFT.

Further, the present invention is not limited to the TFT structure of FIG. 1C, and if necessary, a lightly doped drain (LDD) having an LDD region between a channel formation region and a drain region (or source region). ) Structure may be used. In this structure, a region to which an impurity element is added at a low concentration is provided between a channel formation region and a source region or a drain region formed by adding an impurity element at a high concentration, and this region is referred to as an LDD region. I'm calling. Further, a so-called GOLD (Gate-drain Overlapped LDD) structure in which an LDD region is disposed so as to overlap with a gate electrode through a gate insulating film may be employed.

  Although the top gate TFT has been described here as an example, the present invention can be applied regardless of the TFT structure, and can be applied to, for example, a forward staggered TFT.

  Since the present invention uses a CW laser instead of a conventional pulsed laser, the semiconductor layer 16a having a flat surface without a ridge can be obtained. In addition, the gate insulating films 24a and 24b can be made thinner.

(Embodiment 2)
A state in which a pseudo CW laser beam is scanned on the surface of a semiconductor film provided over a substrate and a manufactured TFT will be described with reference to FIGS.

  FIG. 2A shows a top view of a state in which a laser beam 31 is scanned over the surface of the amorphous semiconductor film. A laser beam 31 having a long elliptical spot is scanned in a scanning direction 32 indicated by an arrow in the drawing to partially form a crystal region.

  Note that although not illustrated in FIG. 2A, an example in which a top-gate TFT is manufactured, a base insulating film is provided over a substrate having an insulating surface, and an amorphous semiconductor is formed thereover. A film is formed.

In crystallization of the amorphous semiconductor film, in this embodiment, a 1.8 W YVO ₄ laser is used, the oscillation frequency is 80 MHz, and the pulse width is about 12 psec. In the present invention, the oscillation frequency is not limited to 80 MHz and may be 10 MHz or more. Furthermore, in the present invention, the upper limit of the frequency of pulse oscillation may be set to 100 GHz so that a laser beam having a uniform wavefront and a high roundness can be obtained to such an extent that the light collecting property is not hindered. Further, the present invention is not particularly limited to a solid-state laser capable of obtaining an output of about 1.8 W. For example, a large laser having an output reaching 300 W may be used.

In this embodiment, it is desirable that the laser oscillator be a stable resonator and be in the TEM ₀₀ oscillation mode. In the case of the TEM ₀₀ mode, the laser beam has a Gaussian intensity distribution and has excellent light collecting properties, so that the beam spot can be easily processed.

A laser beam 31 having a size of about 10 μm × 100 μm is formed on the irradiated surface by an optical system. The total width of the laser beam on the irradiated surface is 100 μm. Then, the stage is scanned in the short axis direction of the laser beam 31. The beam spot scanning speed is several tens of mm / mm.
A value of about sec to several thousand mm / sec is appropriate, and is 400 mm / sec here. By this stage scanning, the laser beam 31 is scanned relative to the surface of the semiconductor film in the scanning direction 32 shown in FIG. In the irradiation region 34a irradiated with the laser beam spot, the semiconductor film is melted, the solid-liquid interface continuously moves in the scanning direction, and the crystal grows in the scanning direction. A state is formed in which crystal grains of a single crystal having a length of about 10 μm and a length of about 10 to 30 μm are spread.

  Then, as shown in FIG. 2A, it is preferable that a region 35a that becomes a channel of a TFT to be formed later is located inside the irradiation region 34a. In particular, as shown in the top view of FIG. 2B, when three TFTs are electrically connected in parallel, a region to be a channel of the three TFTs is set to be inside the irradiation region 34a. In FIG. 2B, the design is such that three TFTs are arranged side by side in a direction perpendicular to the scanning direction. That is, the width (LP width) of the irradiation region 34a is the channel width W1 of the first TFT, the channel width W3 of the second TFT, the channel width W5 of the third TFT, and the channel spacings W2 and W4. One of the features of the present invention is to make the sum larger than (W1 + W2 + W3 + W4 + W5).

  Further, in FIG. 2B, the design is such that three TFTs are arranged side by side in the scanning direction, and a total of nine TFTs are arranged. Further, these channel formation regions are arranged at equal intervals.

  In addition, an irradiation region 34 b that is a microcrystal is formed in a region between the irradiation region 34 a and the non-irradiation region 33. Here, a microcrystalline region of 15 μm is formed on both sides of a crystal grown region having an LP width of 70 μm out of 100 μm of the entire width of the irradiated region (laser beam full width). Since it is not preferable that the irradiation region 34b to be a microcrystal be a part of the active layer of the TFT, it should not be overlapped with the region 35b to be the active layer.

  When irradiation is performed on the entire surface of the semiconductor film, the repeated scanning pitch is 85 μm, and the microcrystalline regions of 15 μm overlap each other.

  When the laser beam irradiation is finished, patterning is performed to form two island-shaped semiconductor layers, and a gate insulating film, a gate electrode, an interlayer insulating film, a source wiring, a drain wiring, and the like are formed using a known technique. A thin film transistor is completed.

  FIG. 2B shows how the completed three TFTs are connected. Although FIG. 2B is shown corresponding to FIG. 2A, in reality, shrinkage of the substrate or the like occurs due to heat treatment or the like during the TFT manufacturing process, and the size of the active layer is reduced.

In FIG. 2B, a first semiconductor layer 36a, a second semiconductor layer 36b, and a third semiconductor layer 36c are arranged in parallel. The three TFTs have a common gate wiring 37, source wiring 38, and drain wiring 39, and are electrically connected in parallel.

In the case of the continuous wave laser used in Embodiment Mode 1, the time for which laser light is irradiated to any one point of the semiconductor film is on the order of 10 μsec. However, in this embodiment, since the laser beam is oscillated at a high oscillation frequency exceeding 10 MHz, the pulse width is 1 nsec or less, and the time for which one point is irradiated with the laser beam can be increased 10 ⁻⁴ times. In addition, the peak output can be dramatically increased as compared with a continuous wave laser. Therefore, when the semiconductor film formed on the substrate is crystallized, the amount of heat given to the substrate can be significantly suppressed as compared with a continuous wave laser, and thus the substrate shrink, the semiconductor film, and other films The diffusion of impurities occurring between the two can be prevented, thereby improving the characteristics of the semiconductor element and increasing the yield.

  In addition, since the pseudo CW laser is used instead of the conventional pulsed laser, the first semiconductor layer 36a, the second semiconductor layer 36b, and the third semiconductor layer 36c having a flat surface without a ridge can be obtained. . In addition, the gate insulating film can be further thinned.

  In addition, since a remarkably high oscillation frequency is used compared to a conventional pulsed laser, interference caused by light reflection on the back surface of the substrate can be suppressed even when laser light is irradiated from a direction perpendicular to the substrate. The following effects can also be obtained. Since laser light can be irradiated from a direction perpendicular to the substrate, optical design is facilitated, and the energy distribution of the obtained beam spot can be made more uniform.

  Further, this embodiment mode can be combined with Embodiment Mode 1.

  The present invention having the above-described configuration will be described in more detail with the following examples.

  In this embodiment, the configuration of the laser irradiation apparatus will be described with reference to FIG.

Reference numeral 101 denotes a pulse oscillation laser oscillator. In this embodiment, a 1.8 W YVO ₄ laser is used. Reference numeral 102 corresponds to a nonlinear optical element. The laser oscillator 101 is a stable resonator and is preferably in a TEM ₀₀ oscillation mode. In the case of the TEM ₀₀ mode, the laser beam has a Gaussian intensity distribution and has excellent light collecting properties, so that the beam spot can be easily processed. The laser light oscillated from the laser oscillator 101 is converted into the second harmonic (532 nm) by the nonlinear optical element 102. Although it is not necessary to limit to the second harmonic in particular, the second harmonic is superior to the higher harmonics in terms of energy efficiency. The oscillation frequency is 80 MHz and the pulse width is about 12 psec.

The oscillation frequency is not limited to 80 MHz and may be 10 MHz or more. Furthermore, in the present invention, the upper limit of the frequency of pulse oscillation may be set to 100 GHz so that a laser beam having a uniform wavefront and a high roundness can be obtained to such an extent that the light collecting property is not hindered.

In the laser irradiation apparatus of FIG. 3, the nonlinear optical element 102 may be provided in a resonator included in the laser oscillator 101, or a resonator including a nonlinear optical element is provided in addition to the fundamental laser oscillator. May be. The former has the advantage that the device becomes smaller and precise control of the resonator length becomes unnecessary, and the latter has the advantage that the interaction between the fundamental wave and the harmonic can be ignored.

The nonlinear optical element 102 includes KTP (KTiOPO ₄ ), which has a relatively large nonlinear optical constant,
BBO (β-BaB ₂ O ₄ ), LBO (LiB ₃ O ₅ ), CLBO (CsLiB ₆ O ₁₀ ), GdYCOB (YCa ₄ O (BO ₃ ) ₃ ), KDP (KD ₂ PO ₄ ), KB5, LiNbO ₃ Crystals such as Ba ₂ NaNb ₅ O ₁₅ are used, and the conversion efficiency from the fundamental wave to the harmonic can be increased by using LBO, BBO, KDP, KTP, KB5, CLBO or the like.

Since the laser light is normally emitted in the horizontal direction, the traveling direction of the laser light oscillated from the laser oscillator 101 is reflected by the reflection mirror 103 so that the angle (incident angle) from the vertical direction is θ. Converted. In this embodiment, θ = 18 °. The first laser light whose traveling direction has been converted is processed into a beam spot shape by the lens 104 and irradiated onto the object to be processed placed on the stage 107. In FIG. 3, the semiconductor film 106 formed over the substrate 105 corresponds to an object to be processed. In FIG. 3, the reflection mirror 103 and the lens 104 correspond to an optical system for condensing laser light on the semiconductor film 106.

FIG. 3 shows an example in which a plano-convex spherical lens is used as the lens 104. The plano-convex spherical lens has a focal length of 20 mm. The plane is arranged in parallel with the substrate 105 so that the laser beam is incident on the center of the curved surface. The distance between the plane of the plano-convex spherical lens and the semiconductor film 106 is 20 mm. Thereby, a beam spot 110 having a size of about 10 μm × 100 μm is formed on the surface of the semiconductor film 106. The fact that the beam spot 110 can be elongated is due to the astigmatism of the lens 104.

  As shown in FIG. 3, in the case where the substrate 105 on which the semiconductor film 106 is formed is used as an object to be processed, when the semiconductor film 106 is an amorphous semiconductor, a laser is used to increase the resistance of the semiconductor film 106 to laser light. It is preferable to perform thermal annealing on the semiconductor film 106 before light irradiation. Specifically, the thermal annealing may be performed, for example, at 500 ° C. for about 1 hour in a nitrogen atmosphere. In addition to thermal annealing, crystallization using a catalytic metal may be performed. The optimum laser light irradiation conditions are substantially the same for both the semiconductor film subjected to thermal annealing and the semiconductor film crystallized using a catalytic metal.

The stage 107 is parallel to the substrate 105 by a robot (X axis uniaxial robot) 108 for scanning in the X axis direction and a robot (Y axis uniaxial robot) 109 for scanning in the Y axis direction. It is possible to move in the XY direction within a simple plane.

Then, the stage 107 is scanned in the short axis direction of the beam spot 110 using the Y-axis uniaxial robot 109. The scanning speed of the stage 107 is suitably about several tens mm / sec to several thousand mm / sec, and here it is set to 400 mm / sec. By the scanning of the stage 107, the beam spot 110 is scanned relative to the surface of the semiconductor film 106. Therefore, the semiconductor film is melted in the region where the beam spot 106 is hit, the solid-liquid interface is continuously moved in the scanning direction, and the crystal is grown in the scanning direction. A state in which single crystal grains having a length of about 10 μm and a length of about 10 to 30 μm are spread (as seen) is formed.

  Next, a scanning path of the beam spot 110 on the surface of the semiconductor film 106 will be described with reference to FIG. When irradiating the entire surface of the semiconductor film 106 corresponding to the object to be processed with laser light, after scanning in one direction using the Y-axis uniaxial robot 109, the X-axis uniaxial robot 108 is used. The beam spot 110 is slid in a direction crossing the scanning direction by the uniaxial robot 109. This sliding distance corresponds to the pitch.

For example, the beam spot 110 is scanned in one direction by the Y-axis uniaxial robot 109. In FIG. 4, the scanning path is indicated by A1. Next, the beam spot 110 is slid in the direction perpendicular to the scanning path A1 using the X-axis uniaxial robot 108. A scanning path by the slide is indicated by B1. Next, the beam spot 110 is scanned in one direction by the Y-axis uniaxial robot 109 in the direction opposite to the scanning path A1. The scanning path is indicated by A2. Next, the beam spot 110 is slid in the direction perpendicular to the scanning path A2 using the X-axis uniaxial robot 108. A scanning path by the slide is indicated by B2. In this manner, the entire surface of the semiconductor film 106 can be irradiated with laser light by sequentially repeating the scanning by the Y-axis uniaxial robot 109 and the scanning by the X-axis uniaxial robot 108.

A region where crystal grains that are irradiated with laser light and grown in the scanning direction are formed has excellent crystallinity. Therefore, extremely high mobility and on-state current can be expected by using this region as a channel formation region of the TFT. However, when there is a portion of the semiconductor film where such high crystallinity is not required, the portion may not be irradiated with laser light. Alternatively, laser light irradiation may be performed under conditions that do not provide high crystallinity, such as increasing the scanning speed.

The scanning of the laser beam is an irradiation system moving type in which the substrate that is the object to be processed is fixed and the irradiation position of the laser beam is moved, and the irradiation position of the laser beam is fixed and the substrate is fixed as shown in FIGS. A moving object to be processed can be used, or a method combining the above two methods can be used. In any case, it is assumed that the relative movement direction of each beam spot with respect to the semiconductor film can be controlled.

  A procedure for manufacturing a TFT will be described below.

  After forming a 200 nm thick silicon oxide on one surface of a 0.7 mm thick glass substrate, and forming a 66 nm thick amorphous silicon (a-Si) film as a semiconductor film thereon by a plasma CVD method In order to increase the resistance of the semiconductor film to the laser, thermal annealing is performed at 500 ° C. for 1 hour in a nitrogen atmosphere.

Then, using the laser irradiation apparatus shown in FIG. 3, the second harmonic (532 nm) of a 1.8 W YVO ₄ laser, TEM ₀₀ mode, oscillation frequency 80 MHz, pulse width 12 psec, scanning speed 400 mm / sec, length 10 μm × Crystallization is performed by irradiating a laser beam with a beam spot having a total width of about 100 μm. Then, a state is obtained in which single crystal grains having a width of several μm and a length of about 10 to 30 μm, which are grown in the scanning direction, are spread in a region having an LP width of 70 μm.

  Then, a plurality of island-shaped semiconductor layers are patterned inside the obtained region having an LP width of 70 μm. For example, in a region having an LP width of 70 μm, a first channel formation region having a channel width W1 (W1 = 20 μm) and a second channel formation region having a channel width W2 (W2 = 20 μm) are arranged in parallel, and the distance between them is set. 10 μm. By doing so, the LP width of the crystal region can be made larger than the sum of the channel width and the interval (the width of the crystal region is 70 μm> 20 μm + 20 μm + 10 μm). The channel length L1 of the first channel formation region is 8 μm, and the channel length L2 of the second channel formation region is 8 μm.

  In the subsequent steps, two TFTs having at least the channel formation region are completed using a known technique, and are electrically connected in parallel. Thus, a first TFT (L1 / W1 = 8 μm / 20 μm) and a second TFT (L2 / W2 = 8 μm / 20 μm) are obtained. The obtained two TFTs are uniformly crystallized in at least two channel formation regions and exhibit substantially the same electrical characteristics.

  If the two TFTs electrically connected in parallel are used in a part of a driver circuit integrated and formed in a display device or the like, the operation characteristics can be made uniform, and a display caused by the driver circuit is caused. Unevenness can be eliminated.

  Similarly, even when a CPU or the like in which an NMOS circuit, a PMOS circuit, or a CMOS circuit is integrally formed using the two TFTs described above, variation in operating characteristics of the thin film transistor can be reduced and uniform operation can be achieved. Can be done.

  In addition, this embodiment can be freely combined with Embodiment Mode 1 or Embodiment Mode 2.

  In this embodiment, a method for manufacturing a semiconductor device will be described with reference to FIGS.

First, a base film 501 is formed over a substrate 500 as illustrated in FIG. As the substrate 500, for example, a glass substrate such as barium borosilicate glass or alumino borosilicate glass, a quartz substrate, a SUS substrate, or the like can be used. In addition, substrates made of plastics typified by PET, PES, PEN, and flexible synthetic resins such as acrylic generally tend to have lower heat-resistant temperatures than the above-mentioned substrates. Any material that can withstand the processing temperature can be used.

The base film 501 is provided to prevent an alkali metal such as Na or an alkaline earth metal contained in the substrate 500 from diffusing into the semiconductor film and adversely affecting the characteristics of the semiconductor element. Therefore, the insulating film is formed using an insulating film such as silicon oxide, silicon nitride, or silicon nitride oxide that can suppress diffusion of alkali metal or alkaline earth metal into the semiconductor film. In this embodiment, a silicon nitride oxide film is formed to a thickness of 10 nm to 400 nm (preferably 50 nm to 300 nm) using a plasma CVD method.

Note that the base film 501 may be a single layer or a stack of a plurality of insulating films. In the case of using a substrate containing an alkali metal or an alkaline earth metal, such as a glass substrate, a SUS substrate, or a plastic substrate, it is effective to provide a base film from the viewpoint of preventing impurity diffusion. However, in the case where diffusion of impurities does not become a problem, such as a quartz substrate, it is not necessarily provided.

Next, a semiconductor film 502 is formed over the base film 501. The thickness of the semiconductor film 502 is 25 nm to 100 nm (preferably 30 nm to 60 nm). Note that the semiconductor film 502 may be an amorphous semiconductor or a polycrystalline semiconductor. As the semiconductor, not only silicon but also silicon germanium can be used.

Next, as shown in FIG. 5B, crystallization is performed by irradiating the semiconductor film 502 with laser light using the laser irradiation apparatus of FIG.

In this embodiment, a YVO ₄ laser having an energy of 2 W, an oscillation mode of TEM _00, a second harmonic (532 nm), an oscillation frequency of 80 MHz, and a pulse width of 12 psec is used as the laser beam.
Note that a beam spot formed on the surface of the semiconductor film 502 by processing laser light with an optical system has a rectangular shape with a short axis of 10 μm and a long axis of 100 μm.

Then, a beam spot is scanned on the surface of the semiconductor film 502 in the direction of a white arrow illustrated in FIG. By setting the oscillation frequency to 80 MHz, the solid-liquid interface can be continuously moved in the direction of the white arrow, so that crystal grains continuously grown in the scanning direction are formed. By forming single crystal grains extending in the scanning direction, it is possible to form a semiconductor film having few crystal grain boundaries at least in the channel direction of the TFT.

Note that laser light may be irradiated in an inert gas atmosphere such as a rare gas or nitrogen. Thereby, roughness of the semiconductor surface due to laser light irradiation can be suppressed, and variation in threshold value caused by variation in interface state density can be suppressed.

By irradiating the semiconductor film 502 with the laser light, the semiconductor film 503 with higher crystallinity is formed.

Next, as illustrated in FIG. 5C, the semiconductor film 503 is patterned to form island-shaped semiconductor films 507 to 509, and the island-shaped semiconductor films 507 to 509 are used to represent the TFT. Various semiconductor elements are formed.

Although not shown, for example, when a TFT is manufactured, a gate insulating film is formed so as to cover the island-shaped semiconductor films 507 to 509. For the gate insulating film, for example, silicon oxide, silicon nitride, silicon nitride oxide, or the like can be used. As a film formation method, a plasma CVD method, a sputtering method, or the like can be used.

Next, a conductive film is formed over the gate insulating film and patterned to form a gate electrode. Then, a gate electrode or a resist film formed and patterned is used as a mask, an impurity imparting n-type or p-type conductivity is added to the island-shaped semiconductor films 507 to 509, and a source region and a drain region are added. Further, an LDD region or the like is formed.

A TFT can be formed by the series of steps described above. Note that the method for manufacturing a semiconductor device of the present invention is not limited to the TFT manufacturing process shown in this embodiment after the formation of an island-shaped semiconductor film. By using a semiconductor film crystallized by the above-described laser light irradiation method as an active layer of a TFT, variations in mobility, threshold value, and on-current between elements can be suppressed.

Further, a crystallization step using a catalytic element may be provided before crystallization with laser light. As the catalytic element, nickel (Ni), germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum (Pt), copper (Cu), An element such as gold (Au) can be used. When a crystallization process using a laser beam is performed after a crystallization process using a catalytic element, the crystal formed during the crystallization using the catalytic element remains on the side closer to the substrate without being melted by the laser beam irradiation. Then, crystallization proceeds using the crystal as a crystal nucleus. Therefore, crystallization by laser light irradiation tends to progress uniformly from the substrate side toward the surface of the semiconductor film, and the crystallinity of the semiconductor film can be improved more than in the case of only the crystallization process by laser light. The surface roughness of the semiconductor film after crystallization by light can be suppressed. Accordingly, variation in characteristics of semiconductor elements formed later, typically TFTs, can be further suppressed, and off-current can be suppressed.

Note that after the catalyst element is added and heat treatment is performed to promote crystallization, the crystallinity may be further increased by laser light irradiation, or the heat treatment step may be omitted. Specifically, after adding a catalyst element, laser light may be irradiated instead of heat treatment to improve crystallinity.

  This embodiment can be freely combined with Embodiment Mode 1, Embodiment Mode 2, or Example 1.

In this example, unlike Example 2, an example in which a crystallization method using a catalytic element is combined with a crystallization method using a laser irradiation apparatus in FIG.

  First, the process up to forming the semiconductor film 502 is performed with reference to FIG. Next, as shown in FIG. 6A, a nickel acetate salt solution containing 1 to 100 ppm of Ni in terms of weight is applied to the surface of the semiconductor film 502 by spin coating. Note that the addition of the catalyst is not limited to the above method, and the catalyst may be added by sputtering, vapor deposition, plasma treatment, or the like. And it heat-processes at 500-650 degreeC for 4 to 24 hours, for example, 570 degreeC and 14 hours. By this heat treatment, a semiconductor film 520 whose crystallization is promoted in the vertical direction from the surface coated with the nickel acetate salt solution toward the substrate 500 is formed (FIG. 6A).

  In the heat treatment, for example, RTA (Rapid Thermal Anneal) using lamp radiation as a heat source or RTA (gas RTA) using a heated gas is performed at a set heating temperature of 740 ° C. for 180 seconds. The set heating temperature is the temperature of the substrate measured with a pyrometer, and this temperature is set as the set temperature during heat treatment. As another method, there is a heat treatment for 4 hours at 550 ° C. using a furnace annealing furnace, which may be used. The lowering and shortening of the crystallization temperature is due to the action of a catalytic metal element.

  In this embodiment, nickel (Ni) is used as a catalyst element. In addition, germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt Elements such as (Co), platinum (Pt), copper (Cu), and gold (Au) may be used.

Next, as shown in FIG. 6B, the semiconductor film 520 is crystallized using the laser irradiation apparatus of FIG. In this embodiment, the second harmonic of a pulsed YVO ₄ laser having an oscillation frequency of 80 MHz and a pulse width of about 12 psec is used as the laser light.

By irradiating the semiconductor film 520 with the laser light, the semiconductor film 521 with higher crystallinity is formed. Note that it is considered that the semiconductor element 521 crystallized using the catalytic element contains the catalytic element (here, Ni) at a concentration of about 1 × 10 ¹⁹ atoms / cm ³ . Next, gettering of the catalytic element present in the semiconductor film 521 is performed.

  First, as illustrated in FIG. 6C, an oxide film 522 is formed on the surface of the semiconductor film 521. By forming the oxide film 522 having a thickness of about 1 nm to 10 nm, the surface of the semiconductor film 521 can be prevented from being roughened by etching in a later etching step. The oxide film 522 can be formed using a known method. For example, it may be formed by oxidizing the surface of the semiconductor film 521 with an aqueous solution in which sulfuric acid, hydrochloric acid, nitric acid, and the like are mixed with hydrogen peroxide water or ozone water, or plasma treatment in an atmosphere containing oxygen Alternatively, it may be formed by heat treatment, ultraviolet irradiation or the like. Alternatively, the oxide film 522 may be formed by another method such as a plasma CVD method, a sputtering method, or an evaporation method.

Next, a gettering semiconductor film 523 containing a rare gas element at a concentration of 1 × 10 ²⁰ atoms / cm ³ or more is formed with a thickness of 25 to 250 nm on the oxide film 522 by a sputtering method. The gettering semiconductor film 523 preferably has a lower film density than the semiconductor film 521 in order to increase the etching selectivity between the semiconductor film 521 and the semiconductor film 521. As the rare gas element, one or more selected from helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) are used.

  Next, heat treatment is performed using a furnace annealing method or an RTA method to perform gettering. In the case of performing furnace annealing, heat treatment is performed at 450 to 600 ° C. for 0.5 to 12 hours in a nitrogen atmosphere. When using the RTA method, the lamp light source for heating is turned on for 1 to 60 seconds, preferably 30 to 60 seconds, and this is repeated 1 to 10 times, preferably 2 to 6 times. The emission intensity of the lamp light source is arbitrary, but the semiconductor film is instantaneously heated to 600 to 1000 ° C., preferably about 700 to 750 ° C.

  By the heat treatment, the catalytic element in the semiconductor film 521 moves to the gettering semiconductor film 523 as indicated by an arrow by diffusion and is gettered.

Next, the gettering semiconductor film 523 is selectively etched and removed. Etching can be performed by dry etching without using plasma with ClF ₃ , or wet etching with an alkaline solution such as an aqueous solution containing hydrazine or tetraethylammonium hydroxide ((CH ₃ ) ₄ NOH). At this time, the oxide film 522 can prevent the semiconductor film 521 from being etched.

  Next, after the oxide film 522 is removed with hydrofluoric acid, the semiconductor film 521 is patterned to form island-shaped semiconductor films 524 to 526 (FIG. 6D). Various semiconductor elements typified by TFTs can be formed using the island-shaped semiconductor films 524 to 526. In the present invention, the gettering step is not limited to the method shown in this embodiment. Other methods may be used to reduce the catalytic element in the semiconductor film.

  In the case of this example, the crystal formed during the crystallization with the catalytic element remains unmelted by laser light irradiation on the side closer to the substrate, and the crystallization proceeds using the crystal as a crystal nucleus. Therefore, crystallization by laser light irradiation easily proceeds uniformly from the substrate side toward the surface, and the crystal orientation thereof is easily aligned, so that surface roughness can be suppressed compared to the case of Example 2. Therefore, variations in characteristics of semiconductor elements formed later, typically TFTs, can be further suppressed.

  Note that in this embodiment, the structure in which the crystallinity is further enhanced by laser light irradiation after the catalyst element is added and then heat treatment is performed to promote crystallization has been described. The present invention is not limited to this, and the heat treatment step may be omitted. Specifically, after adding the catalyst element, laser light irradiation may be applied instead of the heat treatment to improve crystallinity.

  In addition, this embodiment can be freely combined with Embodiment Mode 1, Embodiment Mode 2, Embodiment Mode 1, or Example 2.

  In this example, an example different from Example 3 in which the crystallization method by the laser irradiation apparatus in FIG. 3 is combined with the crystallization method by the catalytic element will be described.

  First, the process up to forming the semiconductor film 502 is performed with reference to FIG. Next, a mask 540 having an opening is formed over the semiconductor film 502. Then, as shown in FIG. 7A, a nickel acetate salt solution containing 1 to 100 ppm of Ni in terms of weight is applied to the surface of the semiconductor film 502 by spin coating. Note that the addition of the catalyst is not limited to the above method, and the catalyst may be added by sputtering, vapor deposition, plasma treatment, or the like. The applied nickel acetate salt solution is in contact with the semiconductor film 502 at the opening of the mask 540 (FIG. 7A).

  Next, heat treatment is performed at 500 to 650 ° C. for 4 to 24 hours, for example, 570 ° C. for 14 hours. By this heat treatment, a semiconductor film 530 in which crystallization is promoted is formed from the surface coated with the nickel acetate salt solution as shown by the solid line arrow (FIG. 7A). The method for the heat treatment is not limited to this, and other methods shown in Embodiment 3 may be used. The catalyst elements listed in Example 3 can be used.

Next, after the mask 540 is removed, as shown in FIG. 7B, the semiconductor film 530 is crystallized using the laser irradiation apparatus of FIG. In this embodiment, a YVO ₄ laser having an energy of 2 W, a second harmonic (532 nm), an oscillation frequency of 80 MHz, and a pulse width of 12 psec is used. By irradiating the semiconductor film 530 with the laser light 538, the semiconductor film 531 with higher crystallinity is formed.

Note that as shown in FIG. 7B, the catalyst element (here, Ni) is contained in the semiconductor film 531 crystallized using the catalyst element at a concentration of about 1 × 10 ¹⁹ atoms / cm ^3. It is thought that. Next, gettering of the catalytic element present in the semiconductor film 531 is performed.

  First, as shown in FIG. 7C, a masking silicon oxide film 532 is formed to a thickness of 150 nm so as to cover the semiconductor film 531, an opening is provided by patterning, and a part of the semiconductor film 531 is exposed. Let Then, phosphorus is added to provide the semiconductor film 531 with a region 533 to which phosphorus is added. In this state, when heat treatment is performed in a nitrogen atmosphere at 550 to 800 ° C. for 5 to 24 hours, for example, 600 ° C. for 12 hours, the region 533 in which phosphorus is added to the semiconductor film 531 serves as a gettering site, and the semiconductor film The catalytic element remaining in 531 is segregated in the gettering region 533 to which phosphorus is added.

Then, by removing the region 533 to which phosphorus is added by etching, the concentration of the catalytic element in the remaining region of the semiconductor film 531 can be reduced to 1 × 10 ¹⁷ atoms / cm ³ or less. Next, after removing the masking silicon oxide film 532, the semiconductor film 531 is patterned to form island-shaped semiconductor films 534 to 536 (FIG. 7D). Various semiconductor elements typified by TFTs can be formed using the island-shaped semiconductor films 534 to 536. In the present invention, the gettering step is not limited to the method shown in this embodiment. Other methods may be used to reduce the catalytic element in the semiconductor film.

  In the case of this example, the crystal formed during the crystallization with the catalytic element remains unmelted by laser light irradiation on the side closer to the substrate, and the crystallization proceeds using the crystal as a crystal nucleus. Therefore, crystallization by laser light irradiation easily proceeds uniformly from the substrate side toward the surface, and the crystal orientation thereof is easily aligned, so that surface roughness can be suppressed compared to the case of Example 2. Therefore, variations in characteristics of semiconductor elements formed later, typically TFTs, can be further suppressed.

  Note that in this embodiment, the structure in which the crystallinity is further enhanced by laser light irradiation after the catalyst element is added and then heat treatment is performed to promote crystallization has been described. The present invention is not limited to this, and the heat treatment step may be omitted. Specifically, after adding the catalyst element, laser light irradiation may be applied instead of the heat treatment to improve crystallinity.

  Further, this embodiment can be freely combined with Embodiment Mode 1, Embodiment Mode 2, Embodiment 1, Embodiment 2, or Embodiment 3.

A structure of a driver circuit and a pixel of a light-emitting device that is one of semiconductor display devices formed using the laser irradiation device of FIG. 3 will be described with reference to FIGS.

In FIG. 8, a base film 6001 is formed over a substrate 6000, and thin film transistors 6002 and 6020 are formed over the base film 6001. A thin film transistor 6002 provided in the pixel portion includes an island-shaped semiconductor film 6003, a gate electrode 6005, and a gate insulating film 6004 sandwiched between the island-shaped semiconductor film 6003 and the gate electrode 6005. The thin film transistor 6020 provided in the driver circuit includes island-shaped semiconductor films 6018 and 6019, a gate electrode 6021, and a gate insulating film 6004 sandwiched between the island-shaped semiconductor film and the gate electrode 6021. ing.

  The island-shaped semiconductor films 6003, 6018, and 6019 are polycrystalline semiconductor films that are crystallized by scanning the laser beam in the channel width direction using the laser irradiation apparatus of FIG. Here, although only two TFTs are illustrated, at least 2 rows × 2 columns of TFTs are provided in the driving circuit and are electrically connected in parallel. Variation in circuit operation can be reduced by forming part of the driver circuit using the method described in Embodiment 1 or 2 described above. Note that the channel length perpendicular to the channel width direction corresponds to the length of the channel formation region overlapping with the gate electrode 6021.

For the gate insulating film 6004, silicon oxide, silicon nitride, or silicon oxynitride can be used. A film in which these layers are stacked, for example, a film in which SiN is stacked on SiO ₂ may be used as the gate insulating film. The gate electrode 6005 is formed using an element selected from Ta, W, Ti, Mo, Al, and Cu, or an alloy material or a compound material containing the element as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, instead of a single conductive film, a conductive film composed of a plurality of layers may be stacked.

  The transistors 6002 and 6020 are covered with a first interlayer insulating film 6006, and a second interlayer insulating film 6007 and a fourth interlayer insulating film 6009 are stacked over the first interlayer insulating film 6006. Yes. The first interlayer insulating film 6006 can be formed using a single layer or a stack of silicon oxide, silicon nitride, or silicon oxynitride films by a plasma CVD method or a sputtering method.

  For the second interlayer insulating film 6007 and the fourth interlayer insulating film 6009, an organic resin film, an inorganic insulating film, an insulating film including a Si—O bond and a Si—CH x bond, such as a siloxane material, or the like is used. Can do. In this embodiment, non-photosensitive acrylic is used.

The third interlayer insulating film 6008 formed over part of the second interlayer insulating film 6007 is etched using the first electrode 6010, the source electrode 6022, and the drain electrode 6023 as a mask after forming the first electrode 6010, the source electrode 6022, and the drain electrode 6023. . As the third interlayer insulating film 6008, a film that hardly transmits a substance that causes deterioration of the light-emitting element such as moisture or oxygen as compared with other insulating films is used. Typically, it is desirable to use, for example, a DLC film, a carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like.

  In FIG. 8, 6017 is a connection electrode, 6024 is a second electrode, 6011 is an electroluminescent layer, 6012 is a third electrode, and the second electrode 6024, the electroluminescent layer 6011, and the third electrode 6012 overlap. The portion where the light-emitting element corresponds to the light-emitting element 6013. The transistor 6002 is a driving transistor that controls a current supplied to the light-emitting element 6013, and is connected to the light-emitting element 6013 directly or in series via another circuit element. The electroluminescent layer 6011 has a structure in which a single light emitting layer or a plurality of layers including a light emitting layer are stacked.

  The second electrode 6024 is formed over the fourth interlayer insulating film 6009. Further, an organic resin film 6014 used as a partition is formed over the fourth interlayer insulating film 6009. Note that although an organic resin film is used as the partition wall in this embodiment, an inorganic insulating film, an insulating film including a Si—O bond and a Si—CHx bond such as a siloxane material, or the like can be used as the partition wall. The organic resin film 6014 has an opening 6015, and a light-emitting element 6013 is formed by overlapping the second electrode 6024, the electroluminescent layer 6011, and the third electrode 6012 in the opening.

  A protective film 6016 is formed over the organic resin film 6014 and the third electrode 6012. As with the third interlayer insulating film 6008, the protective film 6016 is a film that hardly transmits a substance that causes deterioration of the light-emitting element such as moisture and oxygen compared to other insulating films, such as a DLC film, A carbon nitride film, a silicon nitride film formed by an RF sputtering method, or the like is used.

  Also, the end of the organic resin film 6014 in the opening 6015 is rounded so that the electroluminescent layer 6011 formed on the organic resin film 6014 partially overlaps so that there is no hole in the end. Is desirable. Specifically, it is desirable that the radius of curvature of the curve drawn by the cross section of the organic resin film in the opening is about 0.2 to 2 μm. With the above structure, coverage of an electroluminescent layer or a third electrode to be formed later can be improved, and the second electrode 6024 and the third electrode 6012 are short-circuited in a hole formed in the electroluminescent layer 6011. Can be prevented. Further, by relaxing the stress of the electroluminescent layer 6011, defects called “shrink” in which a light emitting region is reduced can be reduced, and reliability can be improved.

Note that FIG. 8 illustrates an example in which a positive photosensitive acrylic resin is used as the organic resin film 6014. The photosensitive organic resin includes a positive type in which a portion exposed to energy rays such as light, electrons, and ions is removed, and a negative type in which the exposed portion remains. In the present invention, a negative organic resin film may be used. Alternatively, the organic resin film 6014 may be formed using photosensitive polyimide. When the organic resin film 6014 is formed using negative acrylic, an end portion of the opening 6015 has an S-shaped cross-sectional shape. At this time, it is desirable that the radius of curvature at the upper end and the lower end of the opening is 0.2 to 2 μm.

  Note that one of the second electrode 6024 and the third electrode 6012 corresponds to an anode and the other corresponds to a cathode.

  For the anode, other light-transmitting oxide conductive materials such as indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), and gallium-added zinc oxide (GZO) can be used. . Indium tin oxide containing ITO and silicon oxide (hereinafter referred to as ITSO) or indium oxide containing silicon oxide mixed with 2 to 20% zinc oxide (ZnO) may be used. In addition to the light-transmitting oxide conductive material as an anode, in addition to a single layer film made of, for example, one or more of TiN, ZrN, Ti, W, Ni, Pt, Cr, Ag, Al, etc., titanium nitride and A stack of a film containing aluminum as its main component, a three-layer structure of a titanium nitride film, a film containing aluminum as its main component, and a titanium nitride film can be used. However, when light is extracted from the anode side with a material other than the light-transmitting oxide conductive material, the light-transmitting oxide film is formed to have a film thickness that allows light to pass (preferably about 5 nm to 30 nm).

As the cathode, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a low work function can be used. Specifically, alkali metals such as Li and Cs, and alkaline earth metals such as Mg, Ca, and Sr, alloys containing these (Mg: Ag, Al: Li, Mg: In, etc.), and compounds thereof ( In addition to CaF ₂ and CaN, rare earth metals such as Yb and Er can be used. In the case where an electron injection layer is provided in the electroluminescent layer 6011, another conductive layer such as Al can be used. When light is extracted from the cathode side, other light-transmitting oxide conductive materials such as indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), and gallium-added zinc oxide (GZO) are used. It is possible to use. Indium tin oxide containing ITO and silicon oxide (hereinafter referred to as ITSO) or indium oxide containing silicon oxide mixed with 2 to 20% zinc oxide (ZnO) may be used. In the case of using a light-transmitting oxide conductive material, it is preferable to provide an electron injection layer in the electroluminescent layer 6011 to be formed later. In addition, without using a light-transmitting oxide conductive material, light can be extracted from the cathode side by forming the cathode with a film thickness that allows light to pass therethrough (preferably, about 5 nm to 30 nm). In this case, a light-transmitting conductive layer may be formed using a light-transmitting oxide conductive material so as to be in contact with or under the cathode so as to suppress the sheet resistance of the cathode.

  Note that FIG. 8 illustrates a structure in which light emitted from the light-emitting element passes through the substrate 6000; however, a light-emitting device having a structure in which light is directed to the side opposite to the substrate may be used.

  Actually, when completed up to FIG. 8, packaging with a protective film (laminated film, UV curable resin film, etc.) or a translucent cover material with high air tightness and low outgassing so as not to be exposed to the outside air ( (Encapsulation) is preferable. At that time, the reliability of the light emitting element is improved by making the inside enclosed with the cover material an inert atmosphere or arranging a hygroscopic material (for example, barium oxide) inside.

  Note that although a light-emitting device is used as an example of a semiconductor display device in this embodiment, a semiconductor display device formed using the manufacturing method of the present invention is not limited thereto.

  This embodiment can be freely combined with Embodiment Mode 1, Embodiment Mode 2, Embodiment 1, Embodiment 2, Embodiment 3, or Embodiment 4.

In Example 5, an example of a bottom emission type light emitting device is shown, but in this example, an example of manufacturing a top emission type light emitting device is shown.

First, a base insulating film is formed over the first substrate 401. The first substrate 401 is not particularly limited as long as it has flatness and heat resistance. As the base insulating film, a base film made of an insulating film such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed.

  Next, a semiconductor layer is formed over the base insulating film. The semiconductor layer is formed by forming a semiconductor film having an amorphous structure by a known means (such as sputtering, LPCVD, or plasma CVD), and then using the laser irradiation apparatus shown in FIG. A crystalline semiconductor film obtained by performing the crystallization treatment according to Embodiment Mode 2 is formed by patterning into a desired shape using a first photomask.

In this embodiment, a solid-state laser capable of continuous oscillation is used, and the second to fourth harmonics of the fundamental wave are applied. Typically, a second harmonic (532 nm) or a third harmonic (355 nm) of an Nd: YVO ₄ laser (fundamental wave 1064 nm) may be applied.

The semiconductor layer is formed with a thickness of 25 to 80 nm (preferably 30 to 70 nm). There is no limitation on the material of the crystalline semiconductor film, but the crystalline semiconductor film is preferably formed of silicon or a silicon germanium (SiGe) alloy.

Next, after removing the resist mask, a gate insulating film is formed to cover the semiconductor layer. The gate insulating film is formed by plasma CVD, sputtering, or thermal oxidation, and has a thickness of 1 to 200 nm.

  Next, a conductive film with a thickness of 100 to 600 nm is formed over the gate insulating film. Here, a conductive film formed by stacking a TaN film and a W film is formed by sputtering. Here, the conductive film is a laminate of a TaN film and a W film, but is not particularly limited, and an element selected from Ta, W, Ti, Mo, Al, and Cu, or an alloy containing the above element as a main component A single layer of a material or a compound material, or a stacked layer thereof may be used. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used.

  Next, a resist mask is formed using a second photomask, and etching is performed using a dry etching method or a wet etching method. Through this etching process, the conductive film is etched to form the gate electrode of the TFT 404.

Next, after removing the resist mask, a resist mask is newly formed using a third photomask. In order to form an n-channel TFT (not shown) here, an impurity element imparting n-type conductivity (typical) First, a first doping step is performed for doping phosphorus or As) at a low concentration. The resist mask covers a region to be a p-channel TFT and the vicinity of the conductive layer. Through-doping is performed through the insulating film in the first doping step, and an n-type low concentration impurity region is formed. One light emitting element is driven by using a plurality of TFTs, but the above doping step is not particularly necessary when driven by only a p-channel TFT.

Next, after removing the resist mask, a resist mask is newly formed by using a fourth photomask, and a semiconductor film is doped with an impurity element (typically boron) imparting p-type conductivity to the semiconductor at a high concentration. Step 2 is performed. Through-doping is performed through the gate insulating film in the second doping step, and a p-type high concentration impurity region is formed.

Next, a resist mask is newly formed using a fifth photomask, and an impurity element imparting n-type conductivity to the semiconductor (typically phosphorus or As) is formed in order to form an n-channel TFT (not shown) here. A third doping step is performed to dope the silicon at a high concentration. The resist mask covers a region to be a p-channel TFT and the vicinity of the conductive layer. Through-doping is performed through the gate insulating film in the third doping step to form an n-type high concentration impurity region.

  After that, after removing the resist mask and forming an insulating film containing hydrogen, the impurity element added to the semiconductor layer is activated and hydrogenated. As the insulating film containing hydrogen, a silicon nitride oxide film (SiNO film) obtained by a PCVD method is used.

  Next, a planarization film 410 that is the second layer of the interlayer insulating film is formed. As the planarizing film 410, an inorganic material (silicon oxide, silicon nitride, silicon oxynitride, or the like), a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist, or benzocyclobutene), or these Is used. Other films used for the planarization film include insulating films made of SiOx films containing alkyl groups obtained by a coating method, such as silica glass, alkylsiloxane polymers, alkylsilsesquioxane polymers, and hydrogenated silsesquioxanes. An insulating film formed using a polymer, a hydrogenated alkylsilsesquioxane polymer, or the like can be used. Examples of siloxane-based polymers include PSB-K1 and PSB-K31, which are Toray-made coating insulating film materials, and ZRS-5PH, which is a catalytic chemical-made coating insulating film material.

Next, contact holes are formed in the interlayer insulating film using a sixth mask. Next, after removing the sixth mask and forming a conductive film (TiN film, Al (C + Ni) alloy film, and TiN film in this order), etching is performed using the seventh mask and wiring (source of TFT) is formed. Wiring, drain wiring, current supply wiring, and the like).

  Next, the seventh mask is removed, and a third interlayer insulating film 411 is formed. As the third interlayer insulating film 411, a photosensitive or non-photosensitive organic material in which a black pigment obtained by a coating method is dispersed is used. In this embodiment, an interlayer insulating film having a light shielding property is used to improve contrast and absorb stray light. Further, in order to protect the third interlayer insulating film, a silicon nitride oxide film (SiNO film) obtained by a PCVD method may be stacked as the fourth interlayer insulating film. In the case where a fourth interlayer insulating film is provided, it is preferable that after the first electrode is patterned in a later step, the first electrode is selectively removed using the mask.

  Next, a contact hole is formed in the third interlayer insulating film 411 using an eighth mask.

  Next, after forming a reflective conductive film and a transparent conductive film, patterning is performed using a ninth mask to obtain a stack of the reflective electrode 412 and the transparent electrode 413. As the reflective electrode 412, an Ag, Al, or Al (C + Ni) alloy film is used. As the transparent electrode 413, in addition to indium tin oxide (ITO), for example, indium tin oxide (ITSO) containing Si element or IZO (Indium Zinc) in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide. A transparent conductive material such as Oxide) can be used.

Next, an insulator 419 serving as a partition wall is formed by covering the ends of the reflective electrode 412 and the transparent electrode 413 using a tenth mask. As the insulator 419, a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist or benzocyclobutene), or an SOG film (for example, an SiOx film containing an alkyl group) is formed with a thickness of 0. It is used in the range of 8 μm to 1 μm.

Next, a layer 414 containing an organic compound is formed by an evaporation method or a coating method. In order to achieve full color, 414 including an organic compound is selectively formed to form three types of pixels of R, G, and B.

Next, the transparent electrode 415, that is, the cathode of the organic light-emitting element is formed over the layer 414 containing the organic compound in a thickness of 10 nm to 800 nm. As the transparent electrode 415, in addition to indium tin oxide (ITO), for example, indium tin oxide containing Si element (ITSO) or indium oxide mixed with 2 to 20% zinc oxide (ZnO) is used. Can do.

As described above, a light emitting element is manufactured.

Next, transparent protective layers 405 and 416 that cover the light emitting element and prevent moisture from entering are formed. As the transparent protective layers 405 and 416, a silicon nitride film, a silicon oxide film, a silicon oxynitride film (SiNO film (composition ratio N> O) or SiON film (composition ratio N <O)) obtained by sputtering or CVD is used. A thin film mainly containing carbon (for example, a DLC film or a CN film) can be used.

  Next, the second substrate 403 and the first substrate 401 are attached to each other with a sealant containing a gap material (filler (fiber rod), fine particles (eg, true sphere)), etc., for ensuring the substrate interval. Note that a filling material 417, typically an ultraviolet curable or thermosetting epoxy resin, is filled between the pair of substrates. The second substrate 403 may be a light transmissive glass substrate, a quartz substrate, or a plastic substrate. By filling a transparent filling material (with a refractive index of about 1.50) between a pair of substrates, the entire transmittance can be improved as compared with a case where a space (inert gas) is provided between the pair of substrates. .

In the light-emitting element of this example, the transparent electrode 415, the transparent protective layers 416 and 405, and the filling material 417 are formed of a light-transmitting material, and are represented from the upper surface side as represented by the white arrows in FIG. Can be daylighted.

  An example of manufacturing a dual emission light-emitting device is described below with reference to FIG.

  First, a base insulating film is formed over a light-transmitting first substrate 501. The first substrate 501 is not particularly limited as long as it has a light-transmitting property.

  Next, a semiconductor layer is formed over the base insulating film. Next, a gate insulating film covering the semiconductor layer and a gate electrode are formed over the gate insulating film.

  Next, doping is appropriately performed to form an n-type low concentration impurity region, a p-type high concentration impurity region, an n-type high concentration impurity region, and the like. Next, after removing the resist mask and forming an insulating film containing hydrogen (a light-transmitting interlayer insulating film), the impurity element added to the semiconductor layer is activated and hydrogenated.

Next, a light-transmitting planarization film 510 which is the second layer of the interlayer insulating film is formed.
As the planarizing film 510 having a light-transmitting property, an inorganic material (silicon oxide, silicon nitride, silicon oxynitride, or the like), a photosensitive or non-photosensitive organic material (polyimide, acrylic, polyamide, polyimide amide, resist, or benzocyclohexane) is used. Butene) or a laminate of these.

Next, after forming a contact hole in the interlayer insulating film, a conductive film (TiN film, Al (C + Ni) alloy film, and TiN film in this order) is formed, and then etching is performed selectively to form wiring (source wiring of TFT) And drain wiring and current supply wiring).

  Next, a third interlayer insulating film 511 is formed. As the third interlayer insulating film 511, an insulating film made of a SiOx film containing an alkyl group obtained by a coating method is used. Further, in order to protect the third interlayer insulating film, a silicon nitride oxide film (SiNO film) obtained by a PCVD method may be stacked as the fourth interlayer insulating film. In the case where a fourth interlayer insulating film is provided, it is preferable that after the first electrode is patterned in a later step, the first electrode is selectively removed using the mask.

  Next, contact holes are formed in the third interlayer insulating film 511.

  Next, after forming a transparent conductive film, patterning is performed to obtain a transparent electrode 513. As the transparent electrode 513, in addition to indium tin oxide (ITO), for example, indium tin oxide containing Si element (ITSO) or work such as IZO in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide. A transparent conductive material having a high function (work function of 4.0 eV or more) is used.

  Next, an insulator 519 that covers the end portion of the transparent electrode 513 is formed using a mask.

Next, a layer 514 containing an organic compound is formed by an evaporation method or a coating method.

Next, the transparent electrode 515, that is, the cathode of the organic light-emitting element is formed over the layer 514 containing an organic compound in a thickness range of 10 nm to 800 nm. As the transparent electrode 515, in addition to indium tin oxide (ITO), for example, indium tin oxide containing Si element (ITSO) or IZO in which 2 to 20% zinc oxide (ZnO) is mixed with indium oxide is used. Can do.

Next, transparent protective layers 505 and 516 that cover the light-emitting element and prevent intrusion of moisture are formed. Next, the second substrate 503 and the first substrate 501 are attached to each other by using a sealing material containing a gap material for ensuring the substrate interval. As the second substrate 503, a light-transmitting glass substrate, quartz substrate, or plastic substrate may be used.

  In the light-emitting element thus obtained, the transparent electrode 515 and the filling material 517 are formed of a light-transmitting material, and light is taken from both the upper surface side and the lower surface side, as indicated by the white arrows in FIG. 9B. Can do.

Finally, optical films (polarizing plate or circularly polarizing plate) 506 and 507 are provided to improve contrast.

  For example, an optical film (a λ / 4 plate and a polarizing plate are arranged in the order close to the substrate) 507 is provided on the substrate 501, and an optical film (a λ / 4 plate and a polarization in the order close to the substrate) is provided on the second substrate 503. 506 is provided).

  As another example, an optical film (a λ / 4 plate, a λ / 2 plate, and a polarizing plate are arranged in the order close to the substrate) 507 is provided on the substrate 501, and an optical film (substrate is provided on the second substrate 503). Λ / 4 plate, λ / 2 plate, and polarizing plate are arranged in this order.

As described above, the present invention can be provided with a polarizing plate, a circularly polarizing plate, or a combination thereof depending on the structure of the dual emission display device. As a result, a clear black display can be performed and the contrast is improved. Furthermore, reflection light can be prevented by providing a circularly polarizing plate.

  This embodiment can be freely combined with Embodiment Mode 1, Embodiment Mode 2, Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, or Embodiment 5.

In this embodiment, an example in which an FPC or a driving IC for driving is mounted on an EL display panel manufactured according to the above embodiment will be described.

  10 illustrates an example of a top view of a light-emitting device in which the FPC 1209 is attached to four terminal portions 1208. FIG. Over a substrate 1210, a pixel portion 1202 including a light emitting element and a TFT, a gate side driver circuit 1203 including a TFT, and a source side driver circuit 1201 including a TFT are formed. When the active layer of the TFT is composed of a semiconductor film having a crystal structure, these circuits can be formed on the same substrate. Therefore, an EL display panel that realizes system-on-panel can be manufactured.

Note that the substrate 1210 is covered with a protective film except for the contact portion, and a base layer containing a substance having a photocatalytic function is provided over the protective film.

  In addition, connection regions 1207 provided at two positions so as to sandwich the pixel portion are provided in order to contact the second electrode of the light emitting element with a lower wiring. Note that the first electrode of the light-emitting element is electrically connected to a TFT provided in the pixel portion.

  Further, the sealing substrate 1204 is fixed to the substrate 1210 with a sealant 1205 that surrounds the pixel portion and the driver circuit and a filling material that is surrounded by the sealant. Moreover, it is good also as a structure filled with the filling material containing a transparent desiccant. Further, a desiccant may be disposed in a region that does not overlap with the pixel portion.

  Further, the structure shown in FIG. 10 shows a preferable example of a light emitting device of a relatively large size (for example, 4.3 inches diagonal) of the XGA class, but is not particularly limited, and COG as a part of the driving circuit. The driving IC may be mounted by a method.

  The advantage of the external dimensions of the driving IC over the IC chip is the length of the long side. When a driving IC having a long side of 15 to 80 mm is used, the number necessary for mounting corresponding to the pixel portion is obtained. This is less than when an IC chip is used, and the manufacturing yield can be improved. Further, when the driving IC is formed over the glass substrate, the shape of the substrate used as a base is not limited, and thus productivity is not impaired. This is a great advantage compared with the case where the IC chip is taken out from the circular silicon wafer.

  Alternatively, a TAB method may be employed. In that case, a plurality of tapes may be attached and a driving IC may be mounted on the tapes. As in the case of the COG method, a single drive IC may be mounted on a single tape. In this case, a metal piece or the like for fixing the drive IC may be attached together due to strength problems.

  Further, this embodiment can be freely combined with Embodiment Mode 1, Embodiment Mode 2, Embodiment 1, Embodiment 2, Embodiment 3, Embodiment 4, Embodiment 5, or Embodiment 6.

As a display device and an electronic device of the present invention, a video camera, a camera such as a digital camera, a goggle type display (head mounted display), a navigation system, an acoustic playback device (car audio, audio component, etc.), a notebook type personal computer, Game devices, personal digital assistants (mobile computers, mobile phones, portable game machines, electronic books, etc.), image playback devices equipped with recording media (specifically, digital versatile discs (DVDs), video / audio two-way communication devices, And a device having a display capable of reproducing a recording medium such as a general-purpose remote control device and displaying an image thereof. Specific examples of these electronic devices are shown in FIGS.

11A and 11B illustrate a digital camera, which includes a main body 2101, a display portion 2102, an imaging portion 2103, operation keys 2104, a shutter 2106, and the like. According to the present invention, a digital camera including the display portion 2102 without display unevenness can be realized.

FIG. 12A illustrates a large display device having a large screen of 22 inches to 50 inches, which includes a housing 2001, a support base 2002, a display portion 2003, a speaker portion 2004, an imaging portion 2005, a video input terminal 2006, and the like. . The display device includes all information display devices for personal computers, TV broadcast reception, and the like. According to the present invention, a large display device in which display unevenness and operation variation of a drive circuit are reduced can be completed even with a large screen of 22 inches to 50 inches.

FIG. 12B illustrates a laptop personal computer, which includes a main body 2201, a housing 2202, a display portion 2203, a keyboard 2204, an external connection port 2205, a pointing mouse 2206, and the like. According to the present invention, a notebook personal computer in which display unevenness and operation variation of a driving circuit are reduced can be completed.

FIG. 12C illustrates a portable image reproducing device (specifically, a DVD reproducing device) provided with a recording medium, which includes a main body 2401, a housing 2402, a display portion A2403, a display portion B2404, and a recording medium (DVD or the like). A reading unit 2405, operation keys 2406, a speaker unit 2407, and the like are included. A display portion A2403 mainly displays image information, and a display portion B2404 mainly displays character information. Note that an image reproducing device provided with a recording medium includes a home game machine and the like. According to the present invention, it is possible to complete an image reproducing apparatus in which display unevenness and operation variation of a driving circuit are reduced.

  12D is a perspective view of the portable information terminal, and FIG. 12E is a perspective view illustrating a state in which the portable information terminal is folded and used as a mobile phone. In FIG. 12D, the user operates the operation key 2706a with the right hand finger and operates the operation key 2706b with the left hand finger like a keyboard. According to the present invention, a portable information terminal with reduced display unevenness and operation variation of a driver circuit can be completed.

As shown in FIG. 12E, in the case of folding, the main body 2701 and the housing 2702 are held with one hand, and an audio input portion 2704, an audio output portion 2705, operation keys 2706c, an antenna 2708, and the like are used.

Note that the portable information terminal illustrated in FIGS. 12D and 12E mainly includes a high-quality display portion 2703a that horizontally displays images and characters, and a display portion 2703b that vertically displays.

  As described above, various electronic devices can be completed by using any one of the manufacturing methods or configurations of Embodiment Mode 1, Embodiment Mode 2, and Embodiments 1 to 7 of the present invention.

The figure which shows the upper side figure and sectional drawing of this invention. (Embodiment 1) The figure which shows the top view of this invention. (Embodiment 2) The figure of a laser irradiation apparatus. The figure which shows the scanning path | route in the surface of a semiconductor film of a laser beam. 10A and 10B illustrate a laser light irradiation method and a method for manufacturing a semiconductor device. 10A and 10B illustrate a laser light irradiation method and a method for manufacturing a semiconductor device. 10A and 10B illustrate a laser light irradiation method and a method for manufacturing a semiconductor device. FIG. 6 illustrates a structure of a driver circuit and a pixel of a light-emitting device, which is one of semiconductor display devices formed using a laser irradiation device. Sectional drawing of a light emitting element. The top view of a light emitting module. FIG. 14 illustrates an example of an electronic device. FIG. 14 illustrates an example of an electronic device.

Explanation of symbols

11: Laser beam 12: Scanning direction 13: Unirradiated region (amorphous)
14a: irradiation region (crystal)
14b: Irradiation region (microcrystal)
15a: Channel region 15b: Active layer region 16a: First semiconductor layer 16b: Second semiconductor layer 17: Gate wiring 18: Source wiring 19: Drain wiring

Claims (13)

A semiconductor having a plurality of thin film transistors having an active layer formed by forming a semiconductor thin film on a substrate having an insulating surface, irradiating a laser beam of a continuous wave laser, melting and cooling the semiconductor thin film, and recrystallization. Device,
The plurality of thin film transistors are electrically connected in parallel,
A total (WC + WS) of the total width WC of the channel formation regions of the plurality of thin film transistors and the interval WS between the channel formation regions is smaller than the laser beam width LP of the continuous wave laser. Semiconductor device. A semiconductor thin film is formed on a substrate having an insulating surface, and a laser beam of a pulsed laser having a frequency of 10 MHz to 100 GHz is irradiated to melt and cool the semiconductor thin film to recrystallize the semiconductor thin film. A semiconductor device having a plurality of thin film transistors,
The plurality of thin film transistors are electrically connected in parallel,
The total sum (WC + WS) of the channel formation region widths WC of the plurality of thin film transistors and the interval WS between the channel regions is smaller than the laser beam width LP of the pulsed laser. apparatus. A semiconductor having a plurality of thin film transistors having an active layer formed by forming a semiconductor thin film on a substrate having an insulating surface, irradiating a laser beam of a continuous wave laser, melting and cooling the semiconductor thin film, and recrystallization. Device,
Among the plurality of thin film transistors, at least two thin film transistors are electrically connected in parallel,
A channel formation region width W1 of the first thin film transistor;
An interval W2 between the channel formation region of the first thin film transistor and the channel formation region of the second thin film transistor disposed adjacent to the first thin film transistor;
The semiconductor device characterized in that the total (W1 + W2 + W3) of the channel formation region width W3 of the second thin film transistor is smaller than the laser beam width LP of the continuous wave laser. A semiconductor thin film is formed on a substrate having an insulating surface, and a laser beam of a pulsed laser having a frequency of 10 MHz to 100 GHz is irradiated to melt and cool the semiconductor thin film to recrystallize the semiconductor thin film. A semiconductor device having a plurality of thin film transistors,
Among the plurality of thin film transistors, at least two thin film transistors are electrically connected in parallel,
A channel formation region width W1 of the first thin film transistor;
An interval W2 between the channel formation region of the first thin film transistor and the channel formation region of the second thin film transistor disposed adjacent to the first thin film transistor;
The semiconductor device characterized in that the total (W1 + W2 + W3) of the channel formation region width W3 of the second thin film transistor is smaller than the laser beam width LP of the pulsed laser. 5. The semiconductor device according to claim 1, wherein the plurality of thin film transistors are arranged at equal intervals. 6. The semiconductor device according to claim 1, wherein the semiconductor device is a portable information terminal, a video camera, a digital camera, or a personal computer.   6. The semiconductor device according to claim 1, wherein the semiconductor device is a video / audio bidirectional communication device or a general-purpose remote control device. Forming a semiconductor film on the insulating surface;
Scanning the semiconductor film with a laser beam for crystallizing the semiconductor film,
Selectively etching the semiconductor film to form a first semiconductor layer and a second semiconductor layer;
Fabrication of a semiconductor device for forming a first thin film transistor including a first semiconductor layer having a first channel formation region and a second thin film transistor including a second semiconductor layer having a second channel formation region Is the way
The sum (WC + WS) of the total width WC of the channel formation regions of the first thin film transistor and the second thin film transistor and the interval WS between the channel formation regions is smaller than the laser beam width LP of the laser light. A method for manufacturing a semiconductor device.   9. The method for manufacturing a semiconductor device according to claim 8, wherein the laser beam is a laser beam of a continuous wave laser.   9. The method for manufacturing a semiconductor device according to claim 8, wherein the laser beam is a laser beam of a pulsed laser having a frequency of 10 MHz to 100 GHz.   11. The method for manufacturing a semiconductor device according to claim 8, further comprising a step of heating and crystallizing the semiconductor film before scanning the semiconductor film with the laser beam.   12. The semiconductor according to claim 8, wherein a width direction of the first channel formation region and a width direction of the second channel formation region are perpendicular to the scanning direction of the laser beam. Device fabrication method. 13. The method for manufacturing a semiconductor device according to claim 8, wherein the first thin film transistor and the second thin film transistor are electrically connected in parallel.

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