JP2007221051A - Nitride semiconductor device manufacturing method - Google Patents

Abstract

Provided is a method for manufacturing a nitride semiconductor device in which a yield reduction is suppressed by satisfactorily separating a substrate such as a GaN substrate from a semiconductor device layer made of a nitride semiconductor such as a GaN semiconductor.
SOLUTION: A step of forming a semiconductor element layer 9 on a GaN substrate 1, a step of bonding a surface of the semiconductor element layer 9 and a sapphire substrate 10, and irradiating a laser beam from the sapphire substrate 10 side. A step of separating the semiconductor element layer 9 and the GaN substrate 1 by decomposing the semiconductor element layer side surface of the substrate 1.
[Selection] Figure 2

Description

  The present invention relates to a method for manufacturing a nitride-based semiconductor element suitable for manufacturing a nitride-based semiconductor element such as a nitride-based semiconductor light-emitting element that emits ultraviolet light or blue light.

  In recent years, nitride compound semiconductors such as GaN, InN, and AlN have been used as substitutes for light emitting diodes (LEDs) that emit blue light and green light, semiconductor lasers that emit blue violet light, and mercury lamps. It is actively used as a material for light-emitting elements that emit light in the ultraviolet region and as a material for electronic devices such as high-speed transistors that can operate at high temperatures.

  As a nitride semiconductor element using such a nitride compound semiconductor, a nitride semiconductor layer is formed on a growth substrate, and then a substrate for supporting the nitride semiconductor layer is used for growth. A nitride-based semiconductor light-emitting device in which the light output does not show a saturation tendency up to a high current density has been proposed by replacing the substrate with a substrate with good heat dissipation.

Specifically, for example, in Patent Document 1, from a growth gap GaN substrate having a band gap energy smaller than that of GaN, for example, In _x Ga _1-x N (x = 0.15). A GaN-based semiconductor layer and an electrode layer are formed through a release layer, and a conductive substrate made of Cu-W having a low thermal resistance is bonded thereon, and then the photons that pass through the GaN substrate and are absorbed by the release layer. A light emitting diode is formed by separating the GaN substrate by irradiating the release layer with laser light of energy from the lower side of the GaN substrate (opposite to the surface on which the GaN-based semiconductor layer is formed) and altering the release layer. is doing.
JP 2005-93988 A

  However, most of the substrates made of nitride compound semiconductors such as GaN substrates that are generally suitable for growth substrates of nitride semiconductor layers are GaN layers formed by vapor phase growth on heterogeneous substrates made of sapphire or gallium arsenide. Is formed by removing the heterogeneous substrate after forming the thick film. The growth substrate formed by such a method has a structure in which crystal grains of non-uniform sizes are gathered, and a large number of crystal defects are present. Thus, the laser beam is partially absorbed.

  For this reason, as in the method for manufacturing a nitride-based semiconductor element described in Patent Document 1 described above, a method for separating a substrate by irradiating a release layer from a lower side of a substrate such as a GaN substrate to separate the substrate The irradiation of the light causes deterioration of the substrate (such as crystal decomposition and cracking), which prevents the laser light from being transmitted uniformly through the substrate, resulting in non-uniform irradiation of the release layer with the laser light. As a result, in the conventional manufacturing method described in Patent Document 1, a region with insufficient alteration is formed in the release layer, and it becomes difficult to separate the substrate from the GaN-based semiconductor layer, resulting in a decrease in yield. Happens.

  The present invention has been made in view of the above-mentioned conventional problems, and suppresses a decrease in yield by satisfactorily separating a substrate such as a GaN substrate from a semiconductor element layer made of a nitride semiconductor such as a GaN semiconductor. It is an object of the present invention to provide a method for manufacturing a nitride-based semiconductor device.

  In order to achieve the above object, a method for manufacturing a nitride-based semiconductor device according to the first aspect of the present invention includes a semiconductor device layer having a layer made of at least one nitride-based semiconductor on a first substrate. A step of forming a second substrate on the semiconductor element layer, and a laser beam that passes through the second substrate and the semiconductor element layer and is absorbed by the first substrate. And irradiating from the second substrate side to separate the first substrate.

  According to the method for manufacturing a nitride-based semiconductor element in the first aspect of the present invention, the semiconductor element layer is formed on the semiconductor element layer without irradiating the laser beam from the first substrate side which is a growth substrate for the semiconductor element layer. Since the first substrate is separated by irradiating the laser beam from the second substrate side, the separation state of the substrate due to partial absorption of the laser beam generated by irradiating the laser beam from the growth substrate side. Deterioration can be suppressed and the yield is improved.

  Furthermore, in the method for manufacturing a nitride-based semiconductor element according to the first aspect of the present invention, the laser beam is larger than the band gap energy of the first substrate and is larger than the band gap energy of the semiconductor element layer. Has low photon energy. If comprised in this way, the laser beam irradiated from the 2nd board | substrate side will permeate | transmit a 2nd board | substrate and a semiconductor element layer, will be absorbed by a 1st board | substrate, and can isolate | separate a 1st board | substrate.

In addition, when the band gap energy of the semiconductor element layer is larger than the band gap energy of the main part of the first substrate, the laser light is absorbed by the main part of the first substrate. It is not necessary to form a release layer having a small band gap energy for absorbing laser light between the main part of the substrate and the semiconductor element layer. For this reason, the effect that generation | occurrence | production which has arisen by providing a peeling layer, for example, the lattice defect in a semiconductor element layer, curvature, a crack, etc. can be suppressed is acquired.
In the method for manufacturing a nitride semiconductor device according to the first aspect of the present invention, the main portion of the first substrate is made of a nitride compound semiconductor. If comprised in this way, a semiconductor element layer can be grown on the 1st board | substrate suitable for the growth of a nitride-type semiconductor layer, and also the influence of the crystal defect etc. which are inherent in the 1st board | substrate. The first substrate can be separated without receiving. Further, as the nitride-based compound semiconductor constituting the main portion of the first substrate, for example, a GaN-based semiconductor such as GaN, AlGaN, or InGaN is suitable.

  In the method for manufacturing a nitride-based semiconductor device according to the first aspect of the present invention, the first substrate has an exfoliation layer in which laser light is absorbed at the top. If comprised in this way, a semiconductor element layer will have a band gap energy smaller than the main part of a 1st board | substrate, and the laser beam which permeate | transmits a semiconductor element layer will pass the main part of a 1st board | substrate. Even in the case of transmitting conditions, the laser light is absorbed by the part of the release layer formed on the top of the first substrate, so that the influence of crystal defects and the like inherent in the first substrate is affected. Without receiving, the first substrate can be well separated at the part of the release layer.

  In the method for manufacturing a nitride semiconductor device according to the first aspect of the present invention, the release layer is made of a nitride semiconductor mixed crystal containing In phase-separated by heating.

  A release layer made of a nitride-based semiconductor mixed crystal containing In is phase-separated by being held at a high temperature, and InN, metal In, metal Ga, and the like are segregated in the release layer and become black. The blackened release layer has a wavelength range of light that can be absorbed by absorption of light by InN segregated in the layer, metal In, or metal Ga. For this reason, since the photon energy of the laser light absorbed by the release layer can be further reduced, the selection range of the material of the semiconductor element layer through which the laser light is transmitted is expanded, and the laser light is transmitted through the semiconductor element layer. The adverse effect on the semiconductor element layer due to can be suppressed.

  According to a second aspect of the present invention, there is provided a method for manufacturing a nitride-based semiconductor element, comprising: forming a semiconductor element layer having a layer made of at least one nitride-based semiconductor on a first substrate; A step of forming a second substrate on the semiconductor element layer with less absorption of laser light compared to the first substrate; the second substrate and the semiconductor element layer are transmitted; and Irradiating a laser beam absorbed by the first substrate from the second substrate side to separate the first substrate.

  According to the method for manufacturing a nitride-based semiconductor device according to the second aspect of the present invention, the laser beam is emitted from the second substrate side that has less partial absorption of the laser beam than the first substrate. Reaches the separation surface of the first substrate with little partial absorption, and the first substrate can be well separated, improving the yield.

  According to the present invention, there is provided a method for manufacturing a nitride semiconductor device that suppresses a decrease in yield by satisfactorily separating a substrate such as a GaN substrate from a semiconductor device layer made of a nitride semiconductor such as a GaN semiconductor. can do.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
1 to 4 are cross-sectional views illustrating a method for manufacturing a light-emitting diode using a nitride-based compound semiconductor according to the first embodiment of the present invention.

  First, as shown in FIG. 1A, a base layer 2, an n-type contact layer 3, an n-type cladding layer 4, an active layer are formed on a GaN substrate 1 by using a low pressure MOCVD (Metal Organic Chemical Deposition) method. 5, the carrier block layer 6, the p-type cladding layer 7 and the p-type contact layer 8 are sequentially formed. The GaN substrate 1 is an example of the “first substrate” in the present invention, and the GaN substrate 1 constitutes a main part of the first substrate. The semiconductor element layer 9 composed of the underlayer 2, the n-type contact layer 3, the n-type cladding layer 4, the active layer 5, the carrier block layer 6, the p-type cladding layer 7 and the p-type contact layer 8 is a "semiconductor element of the present invention. It is an example of a “layer”.

Specifically, NH ₃ (ammonia), TMGa (trimethyl gallium), and TMAl with the GaN substrate 1 heated to a growth temperature of about 1000 ° C. to 1200 ° C. (for example, 1150 ° C.) under a pressure of about 76 Torr. An underlying layer 2 made of undoped single crystal Al _0.1 Ga _0.9 N having a thickness of about 0.2 μm is grown on the GaN substrate 1 using a source gas made of (trimethylaluminum), and By adding a dopant gas composed of SiH ₄ , an n-type contact layer 3 composed of single crystal Al _0.2 Ga _0.8 N doped with Si having a thickness of about 0.1 μm on the underlayer 2. Grow.

Next, with the GaN substrate 1, the underlayer 2, and the n-type contact layer 3 held at a growth temperature of about 1000 ° C. to about 1200 ° C. (for example, 1150 ° C.), a source gas composed of NH ₃ , TMGa and TMAl and SiH _The n-type cladding layer 4 made of Si-doped single crystal Al _0.3 Ga _0.7 N having a thickness of about 30 nm is grown on the n-type contact layer 3 using a dopant gas consisting of 4 Let

Next, NH ₃ , TMGa, and TMAl in a state where the GaN substrate 1, the underlayer 2, the n-type contact layer 3, and the n-type cladding layer 4 are maintained at a growth temperature of about 1000 ° C. to about 1200 ° C. (eg, 1150 ° C.). On the n-type cladding layer 4, a well layer made of undoped single crystal Al _0.1 Ga _0.9 N having a thickness of about 2 nm and an undoped layer having a thickness of about 5 nm are formed. Barrier layers made of single crystal Al _0.2 Ga _0.8 N are alternately grown. As a result, an active layer 5 having a multi-quantum well structure consisting of a total of five layers of two well layers and three barrier layers is grown, and further, an undoped single crystal Al _0.4 Ga _{0. The} carrier block layer 6 made of 6N is grown.

Next, the GaN substrate 1, the underlayer 2, the n-type contact layer 3, the n-type cladding layer 4, the active layer 5, and the carrier block layer 6 were maintained at a growth temperature of about 1000 ° C. to about 1200 ° C. (eg, 1150 ° C.). In the state, a single crystal Al ₀ doped with Mg having a thickness of about 50 nm on the carrier block layer 6 using a source gas composed of NH ₃ , TMGa and TMAl and a dopant gas composed of CP ₂ Mg. _.3 Ga _0.7 N p-type cladding layer 7 is grown, and on the p-type cladding layer 7, Mg having a thickness of about 5 nm is doped with single crystal Al _0.1 Ga _0.9. A contact layer 8 made of N is grown.

  Thereafter, the p-type cladding layer 7 and the p-type contact layer 8 are made p-type by performing heat treatment or electron beam treatment. In this way, the semiconductor element layer 9 constituted by the base layer 2, the n-type contact layer 3, the n-type cladding layer 4, the active layer 5, the carrier block layer 6, the p-type cladding layer 7 and the p-type contact layer 8 is formed. Form.

  Thereafter, as shown in FIG. 1B, a transparent sapphire substrate 10 having a thickness of about 300 μm whose both surfaces are mirror-polished is prepared, and a transparent adhesive made of an acrylic resin is used to form a semiconductor. The p-type contact layer 8 exposed on the surface of the element layer 9 and the sapphire substrate 10 are joined. The sapphire substrate 10 is an example of the “second substrate” in the present invention.

  Thereafter, as shown in FIG. 2, the semiconductor element layer 9 and the GaN substrate 1 are separated by irradiating laser light from the sapphire substrate 10 side to decompose the surface of the GaN substrate 1 on the semiconductor element layer side. An arrow X in FIG. 2 indicates the irradiation direction of the laser light, and an arrow Y in FIG. 2 indicates the scanning direction of the laser light. Further, a dotted line E in FIG. 2 indicates a portion in which a part of the GaN substrate 1 is decomposed by absorbing the laser light and irradiating the laser.

Specifically, first, from the sapphire substrate side, the third harmonic (for example, wavelength: about 355 nm) of Nd: YAG (or Nd: YVO ₄ or the like) laser light is changed from about 200 mJ / cm ⁻² to about 1000 mJ / cm. Irradiation is performed intermittently while scanning in a predetermined direction at an energy density of ⁻² . FIG. 9 is a diagram illustrating a scan locus of laser light. FIG. 9A is a schematic view of the entire wafer (GaN substrate 1, semiconductor element layer 9, and sapphire substrate 10) viewed from the sapphire substrate side, and FIG. 9B is a diagram of (A) of FIG. 9A. It is an enlarged view of a part. As shown in FIG. 9B, the laser beam extends over the entire area of the sapphire substrate 10 while drawing a locus as indicated by an arrow A in FIG. 9A so that adjacent ones of the irradiation parts B overlap each other. Irradiated. A circle B schematically shows an irradiation part of the laser beam on the sapphire substrate 10. By irradiating the spot intermittently in this way, the laser beam is irradiated from the sapphire substrate side.

Here, the laser beam is larger than the band gap energy (about 3.4 eV: about 365 nm in terms of wavelength) of the GaN substrate 1 and the active layer 5 having the smallest band gap energy among the semiconductor element layers 9. It is assumed that the photon energy is smaller than the band gap energy (about 3.7 eV: about 335 nm in terms of wavelength) of the well layer (Al _0.1 Ga _0.9 N).

  In the present embodiment, a laser beam having a wavelength of about 355 nm is used as an example of the laser beam falling within the above range.

The irradiated laser light passes through the translucent sapphire substrate 10 and the semiconductor element layer 9 and is absorbed by the surface portion of the GaN substrate 1 on the semiconductor element layer 9 side. As a result, the GaN crystal on the surface portion of the GaN substrate 1 on the semiconductor element layer 9 side is decomposed into Ga and N ₂ by laser light irradiation. Thereafter, the entire wafer (GaN substrate 1, semiconductor element layer 9, sapphire substrate 10) is heated to about 50 ° C., and Ga decomposed by laser light is brought into a molten state, so that the semiconductor element layer 9 and the GaN substrate 1 Isolate.

  Thereafter, the underlying layer 2 exposed after the separation of the GaN substrate 1 is removed by polishing or etching to expose the n-type contact layer 3, and then, as shown in FIG. A reflective first n layer of Ti / Al / Ti / Pd / Au having a thickness of about 1 nm / about 100 nm / about 10 nm / about 50 nm / about 500 nm, respectively, on layer 3 using vacuum deposition. The side electrode 11 is formed on the exposed surface of the n-type contact layer 3.

  On the other hand, as shown in FIG. 3B, a Si substrate 12 having a thickness of about 200 μm is prepared, and a fusion layer 13 made of Ti / Pd / Au having a thickness of about 10 nm / about 50 nm / about 500 nm, respectively. It forms on the upper surface of Si substrate 12 by a vacuum evaporation method.

  Next, as shown in FIG. 3C, the Au layer of the n-side electrode 11 formed on the n-type contact layer 3 and the Au layer on the surface of the fusion layer 13 formed on the Si substrate 12 are combined. Then, the fusion layer 13 and the first n-side electrode 11 are joined by thermocompression bonding via a solder made of Au—Sn, Pd—Sn, In—Sn, or the like, or a conductive paste made of Ag. The first n-side electrode 11 improves the conductivity and adhesion between the n-type contact layer 3 and the fusion layer 13 on the Si substrate 12 side.

  Thereafter, as shown in FIG. 4A, the transparent adhesive joining the p-type contact layer 8 and the sapphire substrate 10 is removed by using a release material for acrylic resin, whereby the sapphire substrate. 10 and the p-type contact layer 8 are separated, and the p-type contact layer 8 is exposed again. Further, as shown in FIG. 4B, a light-transmitting property comprising a Ni layer having a thickness of about 2 nm and an Au layer having a thickness of about 3 nm on the p-type contact layer 8 by using a vacuum deposition method. Then, a second n-side electrode 16 made of Al of about 500 nm is formed on the back surface of the Si substrate 12 using a vacuum deposition method.

  Note that electrode pads are attached to the p-type electrode 14 and the second n-side electrode 16 in a later step.

  Finally, the wafer formed in the process of FIG. 4B is subjected to element isolation by dicing or laser scribing along the broken line CC ′ of FIG. Form.

  In this way, the light emitting diode according to the first embodiment is formed.

  In the light emitting diode manufacturing method of the first embodiment described above, laser light is not irradiated from the GaN substrate 1 side which is a growth substrate for the semiconductor element layer, and laser is emitted from the sapphire substrate 10 side formed on the semiconductor element layer 9. Since the GaN substrate 1 is separated by irradiating light, it is possible to suppress the deterioration of the separation state of the substrate due to partial absorption of the laser light that has occurred by irradiating the laser light from the growth substrate side. The yield of substrate separation is improved.

In the first embodiment, the laser light irradiated from the sapphire substrate 10 side has photon energy that is larger than the band gap energy of the GaN substrate 1 and smaller than the band gap energy of the semiconductor element layer 9. The sapphire substrate 10 and the semiconductor element layer 9 are transmitted and absorbed by the GaN substrate 1 so that the GaN substrate 1 can be separated. Further, since the band gap energy of the semiconductor element layer 9 is larger than the band gap energy of the GaN substrate 1 and the laser light is absorbed by the GaN substrate 1, the laser light is transmitted between the GaN substrate 1 and the semiconductor element layer 9. There is no need to form a release layer having a small band gap energy for absorption. For this reason, the problem which has arisen by providing a peeling layer, for example, generation | occurrence | production of the lattice defect in the semiconductor element layer 9, a curvature, a crack, etc. can be suppressed.
(Second embodiment)
5-8 is sectional drawing for demonstrating the manufacturing method of the light emitting diode using the nitride type compound semiconductor which is 2nd embodiment of this invention.

  First, as shown in FIG. 5A, a peeling layer 115, a base layer 102, an n-type contact layer 103, and an n-type cladding layer 104 are formed on a GaN substrate 101 by using a MOCVD (Metal Organic Chemical Deposition) method. The active layer 105, the p-type cap layer 106, the p-type cladding layer 107, and the p-type contact layer 108 are sequentially grown. The GaN substrate 101 and the release layer 115 are examples of the “first substrate” in the present invention, and the GaN substrate 101 constitutes a main part of the first substrate. In addition, the semiconductor element layer 109 including the base layer 102, the n-type contact layer 103, the n-type cladding layer 104, the active layer 105, the p-type cap layer 106, the p-type cladding layer 107, and the p-type contact layer 108 is the present invention. It is an example of a “semiconductor element layer”.

Specifically, a source gas composed of NH ₃ (ammonia), TMGa (trimethylgallium), and TMIn (trimethylindium) in a state where the GaN substrate 101 is maintained at a growth temperature of about 700 ° C. to 1000 ° C. (for example, 770 ° C.). Is used to grow a peeling layer 115 made of undoped single crystal Ga _0.6 In _0.4 N having a thickness of about 20 nm on the GaN substrate 101.

Next, with the GaN substrate 101 and the release layer 115 heated to a growth temperature of about 1000 ° C. to 1200 ° C. (for example, 1150 ° C.), a source gas composed of NH ₃ (ammonia) and TMGa (trimethyl gallium) is used. Then, a base layer 102 made of undoped single crystal GaN having a thickness of about 1.0 μm is grown on the release layer 115, and a dopant gas made of SiH _{4 is} further added to the base layer 102 to form about An n-type contact layer 103 made of single-crystal GaN doped with Si having a thickness of 0.5 μm is grown.

  Note that the release layer 115 is blackened by heating when the base layer is formed. Specifically, a release layer made of a nitride-based semiconductor mixed crystal containing In undergoes phase separation by being held at a high temperature, and InN, metal In, metal Ga, etc. segregate in the release layer, resulting in black Turn into. The blackened release layer has a wavelength range of light that can be absorbed by absorption of light by InN segregated in the layer, metal In, or metal Ga.

Next, the substrate is made of NH ₃ , TMGa, and TMAl in a state where the GaN substrate 101, the release layer 115, the base layer 102, and the n-type contact layer 103 are maintained at a growth temperature of about 1000 ° C. to about 1200 ° C. (eg, 1150 ° C.). A single crystal Al _0.1 Ga _0.9 N doped with Si having a thickness of about 0.15 μm is formed on the n-type contact layer 103 using a source gas and a dopant gas made of SiH _4. An n-type cladding layer 104 is grown.

Next, with the GaN substrate 101, the release layer 115, the base layer 102, the n-type contact layer 103, and the n-type cladding layer 104 held at a growth temperature of about 700 ° C. to about 1000 ° C. (for example, 850 ° C.), NH ₃ , A well layer made of undoped single-crystal Ga _0.9 In _0.1 N having a thickness of about 5 nm and a thickness of about 10 nm on the n-type cladding layer 104 using a source gas made of TMGa and TMIn Barrier layers made of undoped single-crystal GaN having GaN are alternately grown. As a result, an active layer 105 having a multiple quantum well structure consisting of a total of seven layers of three well layers and four barrier layers is grown. Subsequently, the source gas is changed to NH ₃ , TMGa, and TMAl, and a dopant gas composed of CP ₂ Mg is added to form a single crystal Al _0.1 Ga _0.9 N doped with Mg having a thickness of about 10 nm. A p-type cap layer 106 made of is grown.

Next, the GaN substrate 101, release layer 115, base layer 102, n-type contact layer 103, n-type cladding layer 104, active layer 105, and p-type cap layer 106 are heated to about 1000 ° C. to about 1200 ° C. (eg, 1150 ° C.). While maintaining the growth temperature, Mg having a thickness of about 0.1 μm is formed on the p-type cap 106 layer using a source gas composed of NH ₃ , TMGa and TMAl and a dopant gas composed of CP ₂ Mg. A p-type cladding layer 107 made of doped single crystal Al _0.1 Ga _0.9 N is grown.

Subsequently, the GaN substrate 101, release layer 115, base layer 102, n-type contact layer 103, n-type cladding layer 104, active layer 105, p-type cap layer 106, and p-type cladding layer 107 are about 700 ° C. to about 1000 ° C. A thickness of about 5 nm is formed on the p-type cladding layer 107 using a source gas composed of NH ₃ , TMGa, and TMIn and a dopant gas composed of CP ₂ Mg while maintaining the growth temperature (for example, 850 ° C.). A p-type contact layer 108 made of single crystal Ga _0.95 In _0.05 N doped with Mg is grown.

  Thereafter, the p-type cap layer 106, the p-type cladding layer 107, and the p-type contact layer 108 are made p-type by performing heat treatment or electron beam treatment. In this way, the separation layer 115, the base layer 102, the n-type contact layer 103, the n-type cladding layer 104, the active layer 105, the p-type cap layer 106, the p-type cladding layer 107, and the p-type contact layer 108 are configured. A semiconductor element layer 109 is formed.

  Thereafter, as shown in FIG. 5B, a light-transmitting sapphire substrate 110 having a thickness of about 300 μm whose both surfaces are mirror-polished is prepared, and a transparent adhesive made of an acrylic resin is used to form a semiconductor. The p-type contact layer 108 exposed on the surface of the element layer 109 and the sapphire substrate 110 are bonded. The sapphire substrate 110 is an example of the “second substrate” in the present invention.

  Thereafter, as shown in FIG. 6, the semiconductor element layer 109 and the GaN substrate 101 are separated by irradiating laser light from the sapphire substrate 110 side to decompose the peeling layer 115. An arrow X in FIG. 6 indicates the irradiation direction of the laser light, and an arrow Y in FIG. 6 indicates the scanning direction of the laser light. In addition, a dotted line E in FIG. 6 indicates a portion where a part of the peeling layer 115 is decomposed by absorbing the laser light and irradiating the laser.

Specifically, first, from the sapphire substrate side, a second harmonic (for example, wavelength: about 532 nm) of Nd: YAG (or Nd: YVO ₄ or the like) laser light is about 500 mJ / cm ⁻² to about 1000 mJ / cm. Irradiation is performed intermittently while scanning in a predetermined direction at an energy density of ⁻² . FIG. 9 is a diagram illustrating a scan locus of laser light. FIG. 9A is a schematic view of the entire wafer (GaN substrate 101, semiconductor element layer 109, sapphire substrate 110) viewed from the sapphire substrate side, and FIG. 9B is a diagram of FIG. It is an enlarged view of a part. As shown in FIG. 9B, the laser beam extends over the entire area of the sapphire substrate 110 while drawing a locus as indicated by an arrow A in FIG. 9A so that adjacent ones of the irradiation parts B overlap each other. Irradiated. A circle B schematically shows an irradiation part of the laser beam on the sapphire substrate 110. By irradiating the spot intermittently in this way, the laser beam is irradiated from the sapphire substrate side.

Here, the laser beam is larger than the band gap energy (about 2.1 eV: about 590 nm in terms of wavelength) of the release layer 115 and the active layer 105 having the smallest band gap energy among the semiconductor element layers 9. It is assumed that the photon energy is smaller than the band gap energy (about 3.0 eV: about 413 nm in terms of wavelength) of the well layer (Ga _0.9 In _0.1 N).

  In this embodiment, a laser beam having a wavelength of about 532 nm is used as an example of the laser beam that falls within the above range.

The irradiated laser light passes through the sapphire substrate 110 and the semiconductor element layer 109 and is absorbed by the surface portion of the release layer 115 on the semiconductor element layer 109 side. As a result, the release layer 115 is decomposed into Ga, In, and N ₂ by laser light irradiation. Thereafter, the entire wafer (GaN substrate 101, semiconductor element layer 109, sapphire substrate 110) is heated to about 200 ° C., and Ga and In decomposed by laser light are brought into a molten state, so that the semiconductor element layer 109 and the GaN substrate are heated. 101 is separated.

  Thereafter, the underlying layer 102 from which the GaN substrate 101 is separated and exposed is removed by polishing or etching to expose the n-type contact layer 103. Then, as shown in FIG. Reflective first n-side comprising Ti / Al / Ti / Pd / Au having a thickness of about 1 nm / about 100 nm / about 10 nm / about 50 nm / about 500 nm, respectively, on 103 using a vacuum deposition method An electrode 111 is formed on the exposed surface of the n-type contact layer 103.

  On the other hand, as shown in FIG. 7B, a Si substrate 112 having a thickness of about 200 μm is prepared, and a fusion layer 113 made of Ti / Pd / Au having a thickness of about 10 nm / about 50 nm / about 500 nm, respectively. It forms on the upper surface of Si substrate 112 by a vacuum evaporation method.

  Next, as shown in FIG. 7C, the Au layer of the n-side electrode 111 formed on the n-type contact layer 103 and the Au layer on the surface of the fusion layer 113 formed on the Si substrate 112 are combined. The fusion layer 113 and the first n-side electrode 111 are joined by thermocompression bonding via a solder made of Au—Sn, Pd—Sn, In—Sn, or the like, or a conductive paste made of Ag. The first n-side electrode 111 improves the conductivity and adhesion between the n-type contact layer 103 and the fusion layer 113 on the Si substrate 112 side.

  Thereafter, as shown in FIG. 8A, the transparent resin joining the p-type contact layer 108 and the sapphire substrate 110 is removed by using a release material for acrylic resin, whereby the sapphire substrate 110 and the p-type substrate are removed. The p-type contact layer 108 is again exposed by separating the p-type contact layer 108. Further, as shown in FIG. 8B, a light-transmitting film comprising a Ni layer having a thickness of about 2 nm and an Au layer having a thickness of about 3 nm on the p-type contact 108 layer by using a vacuum deposition method. The p-side electrode 114 is formed, and the second n-side electrode 116 made of Al of about 500 nm is formed on the back surface of the Si substrate 112 by vacuum deposition.

  An electrode pad is attached to the p-side electrode 114 and the second n-side electrode 116 in a later step.

  Finally, the wafer formed in the process of FIG. 8B is subjected to element isolation by dicing or laser scribing along the broken line CC ′ of FIG. Form.

  In this way, the light emitting diode according to the second embodiment is formed.

  In the light emitting diode manufacturing method according to the second embodiment described above, laser light is not irradiated from the GaN substrate 101 side, which is a substrate for growing a semiconductor element layer, and laser is emitted from the sapphire substrate 110 formed on the semiconductor element layer 109. Since the GaN substrate 101 is separated by irradiating light, it is possible to suppress the deterioration of the separation state of the substrate due to partial absorption of the laser light that has occurred by irradiating the laser light from the growth substrate side. The yield of substrate separation is improved.

  In the second embodiment, the band gap energy of the semiconductor element layer 9 is smaller than the band gap energy of the GaN substrate 101, and the laser light that passes through the semiconductor element layer 9 necessarily passes through the GaN substrate 101. However, since the laser light is absorbed by the part of the release layer 115 formed on the upper part of the GaN substrate 101, the GaN substrate 101 can be well separated at the part of the release layer 115.

  Further, the release layer 115 in the second embodiment segregates indium nitride (InN), metal In, metal Ga, and the like in the release layer 115 by holding a nitride-based semiconductor containing In at a high temperature. Thus, the release layer is blackened to form a nitride-based semiconductor mixed crystal containing phase-separated In. Absorption of light by InN segregated in the layer, metal In, or metal Ga expands the wavelength range of light that can be absorbed, so that the photon energy of the laser light absorbed by the release layer can be further reduced. Therefore, the selection range of the material of the semiconductor element layer through which the laser beam is transmitted can be expanded, and adverse effects on the semiconductor element layer due to the laser beam transmitting through the semiconductor element layer can be suppressed.

  As described above, in the two embodiments of the present invention, the light emitting diode mainly utilizing the light emitted from the active layer of the nitride-based semiconductor element layer is exemplified. However, the present invention is not limited to this, and the emission from these light emitting elements. The present invention can also be used for manufacturing a light-emitting element in combination with a phosphor that uses light as excitation light. The shape of the semiconductor element layer may be a current confinement structure such as a mesa structure or a ridge structure, and a light waveguide structure of about several μm is formed in the vertical and horizontal directions with respect to the growth surface. It may have an element structure that acts as a semiconductor laser by forming a reflective surface such as a cleaved surface, and it can be applied to a multi-wavelength semiconductor laser by applying the substrate replacement technique according to the present invention. It is. Further, it can be applied to electronic devices such as HEMT (High Electron Mobility Transistor) having a nitride-based semiconductor element layer, SAW (Surface Acoustic Wave) devices, and light receiving elements.

  In the two embodiments of the present invention, the crystal growth of each nitride-based semiconductor layer is performed using the MOCVD method. However, the present invention is not limited thereto, and the HVPE method, the gas source MBE method, or the like is used. Crystal growth of each nitride-based semiconductor layer may be performed. The crystal structure of the nitride compound semiconductor may be a wurtzite type or a zinc blende type structure. Further, the growth plane orientation is not limited to [0001], and may be [11-20] or [1-100].

  Further, instead of the GaN substrates 1 and 101 of the first and second embodiments of the present invention, a substrate made of a nitride compound semiconductor such as a substrate made of a GaN material such as an AlGaN substrate or an InGaN substrate may be applied. Good.

  In the two embodiments of the present invention, the sapphire substrate is exemplified as the light-transmitting substrate. However, the present invention is not limited to this, and the substrate is highly transparent to the laser beam and has a mechanical strength as the support substrate. Anything superior can be applied. Preferably, a material having a thermal expansion coefficient close to that of the semiconductor element layer is used in order to reduce distortion between the semiconductor element layer and the substrate at the time of substrate separation by laser irradiation. Further, preferably, a material having excellent thermal conductivity is used in order to suppress heat storage during substrate separation by laser irradiation. For example, Al (Ga) N, (Mg) ZnO, SiC and the like.

  In the two embodiments of the present invention, Si is exemplified as the support substrate, but other substrate may be used. The support substrate is preferably conductive, and includes a conductive semiconductor (Si, SiC, GaAs, ZnO, etc.), a metal or a composite metal (Al, Fe—Ni, Cu—W, Cu—Mo, etc.), A composite material of metal / metal oxide (Cu-CuO or the like) or the like may be used. In general, metal materials are more suitable than semiconductor materials because they are superior in mechanical properties and hard to break. Furthermore, more preferably, high conductivity and high mechanical strength are obtained by combining a highly conductive metal such as Cu, Ag, or Au with a high hardness metal or metal oxide such as W, Mo, Ni, or CuO. Is to use a material that has both.

  In the second embodiment of the present invention, the layer made of InGaN is exemplified as the peeling layer. However, the present invention is not limited to this, and InAlN, InGaAlN, or a layer obtained by phase separation of these by annealing or the like can be used. . It is also possible to use a metal thin film made of a material that absorbs the laser light to be used.

  In the second embodiment of the present invention, the method of thermally decomposing by heating in the growth stage of the semiconductor element layer is shown as the method for blackening the release layer. However, the present invention is not limited to this, and the semiconductor element is not limited thereto. A method by heating after the growth of the layer, a method by light irradiation, a method by electron beam irradiation, and the like are possible.

  In the second embodiment of the present invention, the release layer is blackened by heating and phase-separated, but the production is possible without blackening.

  In the two embodiments of the present invention, the sapphire substrate used as the second substrate is separated in the manufacturing process, but the nitride-based semiconductor device is completed by using the second substrate as the support substrate. It is also possible. Specifically, after performing the process up to FIG. 3A in the first embodiment, the process corresponding to FIG. 4C is performed, or up to FIG. 7A in the second embodiment. After performing the process, a nitride semiconductor element may be formed by performing a process corresponding to FIG.

It is sectional drawing which shows the manufacturing method of the nitride type semiconductor device by 1st embodiment of this invention. It is typical sectional drawing which shows the manufacturing method of the nitride type semiconductor element by 1st embodiment of this invention. It is sectional drawing which shows the manufacturing method of the nitride type semiconductor device by 1st embodiment of this invention. It is sectional drawing which shows the manufacturing method of the nitride type semiconductor device by 1st embodiment of this invention. It is sectional drawing which shows the manufacturing method of the nitride type semiconductor device by 2nd embodiment of this invention. It is typical sectional drawing which shows the manufacturing method of the nitride type semiconductor element by 2nd embodiment of this invention. It is sectional drawing which shows the manufacturing method of the nitride type semiconductor device by 2nd embodiment of this invention. It is sectional drawing which shows the manufacturing method of the nitride type semiconductor device by 2nd embodiment of this invention. It is a schematic diagram which shows the locus | trajectory of the scan of the laser beam in the manufacturing method of the nitride-type semiconductor element by 1st embodiment and 2nd embodiment of this invention.

Explanation of symbols

1 GaN substrate (first substrate)
2 Underlayer 3 n-type contact layer 4 n-type cladding layer 5 active layer 6 carrier block layer 7 p-type cladding layer 8 p-type contact layer 9 semiconductor element layer 10 sapphire substrate (second substrate)
11 First n-side electrode 12 Si substrate 13 Fusion layer 14 p-side electrode 16 Second n-side electrode 20 Light emitting diode chip 101 GaN substrate (main part of the first substrate)
102 Underlayer 103 n-type contact layer 104 n-type cladding layer 105 active layer 106 carrier block layer 107 p-type cladding layer 108 p-type contact layer 109 semiconductor element layer 110 sapphire substrate (second substrate)
111 First n-side electrode 112 Si substrate 113 Fusion layer 114 p-side electrode 115 Peeling layer 116 Second n-side electrode 120 Light emitting diode chip

Claims (6)

Growing a semiconductor element layer having a layer made of at least one nitride-based semiconductor on the first substrate, forming a second substrate on the semiconductor element layer, and the second substrate And irradiating laser light that is transmitted through the semiconductor element layer and absorbed by the first substrate from the second substrate side, and separating the first substrate. A method for manufacturing a nitride-based semiconductor device. 2. The nitride-based semiconductor according to claim 1, wherein the laser light has a photon energy larger than a band gap energy of the first substrate and smaller than a band gap energy of the semiconductor element layer. Device manufacturing method. 3. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the first substrate is made of a nitride compound semiconductor. 4. The method for manufacturing a nitride semiconductor device according to claim 1, wherein the first substrate has an exfoliation layer in which the laser beam is absorbed on an upper portion thereof. 5. 5. The method for manufacturing a nitride-based semiconductor element according to claim 4, wherein the release layer is made of a nitride-based semiconductor mixed crystal containing In that is phase-separated by heating. A step of forming a semiconductor element layer having a layer made of at least one nitride-based semiconductor on the first substrate; and a partial laser beam on the semiconductor element layer as compared with the first substrate. A step of forming a second substrate with low absorption; and irradiating a laser beam that is transmitted through the second substrate and the semiconductor element layer and absorbed by the first substrate from the second substrate side. And a step of separating the first substrate. A method for manufacturing a nitride-based semiconductor device, comprising:

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