WO2019009092A1 - Plasma treatment method and plasma treatment device - Google Patents

Abstract

[Problem] The present invention addresses the problem of improving productivity. [Solution] The plasma treatment according to the present invention includes heating a substrate supporting table to a first temperature, said substrate supporting table being disposed in a vacuum container. Under first discharge conditions, first plasma is generated between the substrate supporting table and a shower plate facing the substrate supporting table, and the shower plate is heated due to the first plasma and heat of the substrate supporting table. The temperature of the shower plate is monitored in a non-contact manner. After the temperature of the shower plate reaches a second temperature that is higher than the temperature heated by the heat of the substrate supporting table, a process gas is jetted toward the substrate supporting table from the shower plate, and under second discharge conditions, second plasma is generated between the substrate supporting table and the shower plate, thereby treating, using the second plasma, the substrate supported by the substrate supporting table.

Description

Plasma processing method and plasma processing apparatus

The present invention relates to a plasma processing method and a plasma processing apparatus.

2. Description of the Related Art In recent years, with the increase in the area and integration of semiconductor devices, liquid raw materials with a low vapor pressure and a relatively low vapor pressure are used as reaction materials in plasma processing apparatuses such as film forming apparatuses. For example, a heater is provided in a shower plate, the shower plate is heated by the heater, and a low vapor pressure liquid raw material is vaporized and supplied from the shower plate to the reaction chamber to form a film on a substrate. Thermal CVD (Chemical Vapor Deposition) An apparatus is provided (see, for example, Patent Document 1).

Patent No. 3883918

However, in a plasma processing apparatus that applies high frequency power to the shower plate, if the shower plate is provided with a heater, the high frequency power may be superimposed on the heater, which may make it difficult to control the heating of the heater. Also, when cleaning the shower plate, it is necessary to remove the heater from the shower plate. This may reduce the productivity in plasma processing.

In view of the circumstances as described above, an object of the present invention is to provide a plasma processing method and a plasma processing apparatus with improved productivity.

To achieve the above object, a plasma processing method according to an aspect of the present invention includes heating a substrate support disposed in a vacuum vessel to a first temperature. The first plasma is generated between the substrate support and the shower plate facing the substrate under the first discharge condition, and the shower plate is heated by the heat of the substrate support and the first plasma. Ru. The temperature of the shower plate is monitored without contact. After the temperature of the shower plate reaches a second temperature higher than the temperature heated by the heat of the substrate support, a process gas is injected from the shower plate toward the substrate support, and the substrate support is A second plasma is generated between the first and second shower plates under a second discharge condition, and the substrate supported on the substrate support is processed by the second plasma.
According to such a plasma processing method, the temperature of the shower plate can be accurately heated without providing a heater on the shower plate. Also, when cleaning the shower plate, it is not necessary to remove the heater from the shower plate. This improves the productivity in plasma processing.

In the above plasma processing method, in the step of processing the substrate, the second temperature may be a temperature at which the temperature of the shower plate becomes maximum in the step of processing the substrate.
According to such a plasma processing method, since the temperature of the shower plate is already at the maximum temperature before the substrate is subjected to the plasma processing with the process gas, the temperature change of the shower plate is suppressed during the plasma processing with the process gas . Thereby, for example, the thickness of the film formed on the substrate is less likely to vary.

In the above plasma processing method, in the plasma processing step, the second discharge condition includes a discharge power, a reaction gas flow rate, and a processing time. When the plurality of substrates are processed and the second temperature changes each time the substrate is processed, the discharge power, the flow rate of the reaction gas, and the processing time are changed according to the value of the second temperature. At least one may be varied to process the substrate.
According to such a plasma processing method, when processing the substrate every plural sheets, even if the second temperature changes every time the substrate is processed, the discharge power and the reaction gas flow rate according to the value of the second temperature And plasma treatment is performed by changing at least one of the treatment times. Thereby, for example, the film quality of the film formed on the substrate is less likely to vary.

In the above plasma processing method, in the process of the plasma processing, after processing the substrate every plural sheets and processing the substrate every plural sheets, a cleaning gas is jetted to the vacuum container, and the vacuum is processed. The inside of the container may be cleaned.
According to such a plasma processing method, after a plurality of substrates are processed, the cleaning gas is ejected to clean the inside of the vacuum container.

In the above plasma processing method, the temperature of the shower plate may be monitored by a radiation thermometer placed outside the vacuum vessel on the back side of the shower plate.
According to such a plasma processing method, the temperature of the shower plate is measured by a radiation thermometer placed outside the vacuum vessel on the back side of the shower plate. Thereby, the temperature of the shower plate is measured in a noncontact manner, and the radiation thermometer hardly affects the temperature of the shower plate.

In the above plasma processing method, the second discharge condition may be different from the first discharge condition. As a result, plasma processing is performed on the substrate under the second discharge condition different from the first discharge condition.

In order to achieve the above object, a plasma processing apparatus according to an aspect of the present invention includes a vacuum container, a substrate support, a shower plate, a power supply source, a temperature measurement device, and a control device. The vacuum vessel is maintained under reduced pressure. The substrate support is disposed in the vacuum vessel and has a substrate mounting surface and a heating mechanism. The substrate support can set the substrate mounting surface to the first temperature by the heating mechanism, and can support the substrate. The shower plate faces the substrate support. The power supply generates plasma between the substrate support and the shower plate. The temperature of the shower plate is measured without contact. The controller monitors the temperature of the shower plate by the temperature measurement device, and generates a first plasma under a first discharge condition between the substrate support and the shower plate. The control device heats the shower plate by the heat of the substrate support and the first plasma, and a temperature of the shower plate is higher than a temperature at which the temperature of the substrate support is heated by the heat. After that, a process gas is injected from the shower plate toward the substrate support. The control device may generate a second plasma under a second discharge condition between the substrate support and the shower plate, and process the substrate with the second plasma.
According to such a plasma processing apparatus, the temperature of the shower plate can be accurately heated without providing a heater on the shower plate. Also, when cleaning the shower plate, it is not necessary to remove the heater from the shower plate. This improves the productivity in plasma processing.

As described above, according to the present invention, the productivity in plasma processing is improved.

It is a schematic sectional drawing which shows the plasma processing apparatus which concerns on this embodiment. It is a schematic graph which shows the relationship between the process time which concerns on this embodiment, and the temperature of a shower plate. It is a schematic graph which shows the relationship between the process time concerning the comparative example, and the temperature of a shower plate. FIG. (A) is a schematic graph showing the relationship between the process time and the film formation rate according to the present embodiment. FIG. (B) is a schematic graph showing the relationship between the process time and the deposition rate according to the comparative example. It is a schematic graph which shows the relationship between shower plate temperature and film-forming speed | rate. FIG. (A) is a schematic graph showing the relationship between the process time and the film formation rate according to the present embodiment. FIG. (B) is a schematic graph showing the relationship between the process time and the film thickness according to the present embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, XYZ axis coordinates may be introduced.

First Embodiment

FIG. 1 is a schematic cross-sectional view showing a plasma processing apparatus according to the present embodiment.

The plasma processing apparatus 1 according to the present embodiment is, for example, a single-wafer type plasma processing apparatus that plasma-treats the substrates 80 one by one. For example, when one substrate 80 is carried into the vacuum vessel 10 from the outside of the vacuum vessel 10, the substrate 80 is plasma-treated on the substrate support table 30, and carried out of the vacuum vessel 10 after plasma treatment. This series of operations may be repeated for a plurality of substrates 80.

The plasma processing apparatus 1 has both film forming means for forming a film on the substrate 80 by plasma CVD and etching means for removing the film formed on the substrate 80 by dry etching. The plasma processing apparatus 1 includes a vacuum vessel 10, a support 11, a lid 12, a shower head 20, a substrate support 30, a gas supply source 40, a power supply 50, and a temperature measurement device 60. And a control device 70.

The plasma is formed, for example, between the shower head 20 and the substrate support 30 (plasma forming space 10p) by a capacitive coupling method. The plasma is formed, for example, by glow discharge. When the plasma processing apparatus 1 functions as a plasma CVD apparatus, for example, the shower head 20 functions as a cathode, and the substrate support 30 functions as an anode. When the plasma processing apparatus 1 functions as an etching apparatus such as reactive ion etching (RIE), for example, the shower head 20 functions as an anode, and the substrate support 30 functions as a cathode.

The vacuum vessel 10 encloses the substrate support 30. The lid 12 faces the vacuum vessel 10. The support 11 is attached to the lid 12. For example, a vacuum pump (not shown) such as a turbo molecular pump is connected to the vacuum vessel 10 via a gas exhaust port 10 h. Thus, the inside of the vacuum vessel 10 is maintained in a reduced pressure state. For example, in the example of FIG. 1, the space surrounded by the shower head 20, the vacuum vessel 10, and the support portion 11 is maintained in a reduced pressure state by a vacuum pump.

In the plasma processing apparatus 1, the space 15 surrounded by the cover 12, the shower head 20, and the support 11 may be an air atmosphere or a reduced pressure atmosphere. The potential of the lid 12 is, for example, the ground potential. The lid 12 functions as a shield box that shields high frequency waves introduced to the shower head 20. When the space 15 maintains a reduced pressure state, the vacuum vessel 10 and the lid 12 can be combined to form a vacuum vessel. In this case, at least a part of the space in the vacuum vessel can be maintained in a reduced pressure state. The pressure gauge 13 which measures the pressure in the vacuum vessel 10 is installed in the vacuum vessel 10. The pressure gauge 13 is, for example, an ionization vacuum gauge.

The shower head 20 has a head body 21, a shower plate 22, and an insulating member 27. The shower head 20 is supported by the support 11 of the vacuum vessel 10 via the insulating member 27. Thereby, the shower head 20 is insulated from the vacuum vessel 10. The shower head 20 is configured to be detachable from the plasma processing apparatus 1.

An internal space 28 of the shower head 20 is formed by the head body 21 and the shower plate 22. A process gas is introduced into the internal space 28 via a gas introduction pipe 42 provided inside the head body 21. The final end (gas inlet) of the gas introduction pipe 42 is located, for example, near the center of the internal space 28. Thus, the process gas is uniformly supplied to the internal space 28. The number of gas inlets is not limited to one, and a plurality of gas inlets may be provided in the head body 21. Further, in the head main body 21, a flow path through which the heat medium flows may be provided. Thereby, the conductance of the gas introduction pipe 42 is improved. The heat medium can be adjusted to, for example, 25 ° C. or more and 150 ° C. or less (eg, 80 ° C.) by a temperature control mechanism (not shown) provided outside the vacuum vessel 10.

The shower plate 22 is joined in close contact with the head body 21. The shower plate 22 faces the substrate support 30. The shower plate 22 has a gas ejection surface 22s opposite to the internal space 28, a plurality of gas ejection holes 23, and a back surface 22r on the internal space 28 side. Each of the plurality of gas injection holes 23 penetrates the shower plate 22. That is, each of the plurality of gas injection holes 23 continues between the internal space 28 and the plasma formation space 10 p. The process gas is ejected from the gas ejection surface 22 s from the inner space 28 via the plurality of gas ejection holes 23.

In the shower plate 22, a heater heating mechanism is not provided. The reason for this is based on the fact that when the shower plate 22 is provided with a heater, when the high frequency power is supplied to the shower plate 22, the high frequency power is superimposed on the heater and the heating control of the heater becomes difficult. Furthermore, since the shower plate 22 is provided with a plurality of gas injection holes 23, it is difficult to provide a heater and to provide a flow path for a heating medium so as to avoid the individual gas injection holes 23. based on. Therefore, the shower plate 22 is heated from the side of the substrate support 30 by the heat of the substrate support 30, or is heated by plasma or the like formed in the plasma formation space 10p.

The head body 21 and the shower plate 22 include, for example, a conductor such as aluminum (Al), an aluminum alloy, stainless steel or the like. The head body 21 and the shower plate 22 may be subjected to an oxide film treatment as needed to improve the corrosion resistance. The thickness of the shower plate 22 is 5 mm or more and 50 mm or less. The inner diameter of the gas injection hole 23 is 0.3 mm or more and 1 mm or less. Each of the plurality of gas injection holes 23 has the same inner diameter. The pitch in the X-axis direction and the Y-axis direction of the plurality of gas injection holes 23 is 3 mm or more and 20 mm or less.

The substrate support 30 has a substrate placement surface 30s and a heating mechanism 30h for heating the substrate placement surface 30s. The heating mechanism 30 h is, for example, a heater. The substrate 80 is supported by the substrate mounting surface 30s. The substrate mounting surface 30 s is substantially parallel to the gas ejection surface 22 s of the shower plate 22. The substrate support 30 includes, for example, a conductor. The substrate mounting surface 30s may be a conductor or an insulator. For example, an electrostatic chuck may be installed on the substrate mounting surface 30s. When the substrate support 30 includes an insulator or an electrostatic chuck, parasitic capacitance 31 is generated between the substrate 80 and the ground when the substrate support 30 is grounded.

A power supply 55 may be connected to the substrate support 30 so that bias power can be supplied to the substrate 80. The power supply source 55 may be, for example, a DC power supply or an AC power supply. For example, when the plasma processing apparatus 1 is used as an etching apparatus such as RIE, power is supplied to the substrate 80 by the power supply source 55, and a bias potential is applied to the substrate 80. The distance between the substrate support 30 and the shower plate 22 is 15 mm or more and 60 mm or less. As an example, the inter-electrode distance is 20 mm. The distance between the substrate support 30 and the shower plate 22 can be automatically adjusted appropriately by the controller 70.

The substrate mounting surface 30s is heated by the heating mechanism 30h to, for example, a temperature in the range of 60 ° C. or more and 500 ° C. or less. The substrate support 30 may be provided with a cooling mechanism for cooling the substrate mounting surface 30s.

In the plasma processing procedure 1, the planar shapes of the substrate mounting surface 30 s and the shower plate 22 correspond to the planar shape of the substrate 80. For example, when the substrate 80 is a rectangular substrate applied to a panel or the like, the planar shapes of the substrate mounting surface 30s and the shower plate 22 are rectangular. When the substrate 80 is a wafer substrate applied to a semiconductor device or the like, the planar shapes of the substrate mounting surface 30s and the shower plate 22 are circular. The areas of the substrate mounting surface 30s and the shower plate 22 are larger than the area of the substrate 80. The substrate 80 is, for example, a glass substrate having a thickness of 0.5 mm. The size of the substrate 80 is 400 mm × 300 mm or more, for example, 1850 mm × 1500 mm.

The gas supply source 40 has a flow meter 41 and a gas introduction pipe 42. The gas supply source 40 supplies a process gas (film forming gas, etching gas, inert gas, etc.) to the internal space 28 of the shower head 20. The flow rate of the process gas in the gas introduction pipe 42 is controlled by a flow meter 41.

The power supply source 50 includes a power supply 51, a matching circuit unit 52, and a wire 53. The wire 53 is connected near the center of the shower head 20. The matching circuit unit 52 is disposed between the shower head 20 and the power supply 51. The power source 51 is, for example, an RF power source. The power source 51 may be a VHF power source or a DC power source. When the power supply 51 is a DC power supply, the matching circuit unit 52 is removed from the power supply source 50.

The power supply 50 generates a plasma between the substrate support 30 and the shower plate 22. For example, when a process gas is introduced from the shower head 20 to the plasma formation space 10 p and power is supplied from the power source 51 to the shower head 20 via the wiring 53, plasma is generated in the plasma formation space 10 p.

For example, when the plasma processing apparatus 1 is a film forming apparatus, a film forming gas is introduced into the plasma forming space 10 p, a film forming plasma is generated in the plasma forming space 10 p, and a film is formed on the substrate 80. On the other hand, when the plasma processing apparatus 1 is an etching apparatus, an etching gas is introduced into the plasma formation space 10p, etching plasma is generated in the plasma formation space 10p, and the film is removed from the substrate 80.

Further, in the plasma processing apparatus 1, a temperature measurement device 60 that monitors the temperature of the shower plate 22 in a noncontact manner is provided. The temperature measurement device 60 has a first radiation thermometer 61 and a second radiation thermometer 62. Each of the first radiation thermometer 61 and the second radiation thermometer 62 is a fiber optic radiation thermometer.

The first radiation thermometer 61 has an optical fiber focusing part 61 a and a main part 61 b. The second radiation thermometer 62 has an optical fiber focusing part 62a and a main part 62b. Each of the first radiation thermometer 61 and the second radiation thermometer 62 is disposed outside the vacuum vessel 10 on the back surface 22 r side of the shower plate 22.

Each of the optical fiber focusing parts 61 a and 62 a is installed on the lid 12 by a fixing jig 65. For example, the optical fiber focusing portion 61 a is installed at the center of the shower plate 22, and the optical fiber focusing portion 62 a is installed at the end of the shower plate 22. Each of the optical fiber focusing parts 61 a and 62 a is installed vertically toward the shower plate 22. Thereby, the in-plane distribution of the temperature of the shower plate 22 can be measured.

Here, the transparent window material 25 is provided in the head main body 21 to which the optical fiber condensing part 61a faces. Further, the head body 21 is provided with a hole 21 h extending in the vertical direction between the transparent window material 25 and the shower plate 22. Thereby, the first radiation thermometer 61 can receive the emitted light from the back surface 22 r of the shower plate 22 opposed to the optical fiber focusing portion 61 a through the transparent window material 25 and the hole 21 h. Thereby, the first radiation thermometer 61 can detect the temperature of the back surface 22r of the shower plate 22. The transparent window material 25 contains sapphire having high corrosion resistance by reactive gas.

Furthermore, a transparent window member 26 is provided in the head main body 21 to which the optical fiber focusing portion 62a faces. The transparent window material 26 contains sapphire. The head body 21 is provided with a hole 21 h between the transparent window material 26 and the shower plate 22. Thus, the second radiation thermometer 62 can detect the temperature of the back surface 22r of the shower plate 22 opposed to the optical fiber focusing portion 62a via the transparent window material 26 and the hole 21h.

The relationship between the temperature of the gas ejection surface 22s and the temperature of the back surface 22r (temperature calibration curve) during the plasma processing is obtained in advance by simulation, experiment, or the like. Thereby, each of the first radiation thermometer 61 and the second radiation thermometer 62 detects the temperature of the back surface 22 r of the shower plate 22, so that the temperature of the gas ejection surface 22 s can be measured accurately. The temperature calibration curve is stored in the controller 70.

The optical fiber condensers 61 a and 62 a are attached to the lid 12 at the ground potential and insulated from the shower head 20. As a result, even if high frequency power is supplied to the shower head 20, high frequency power is not easily applied to the optical fiber focusing parts 61a and 62a. In addition, even if the head body 21 has a high temperature of 80 ° C. or more, the optical fiber focusing portions 61 a and 62 a are separated from the head body 21 and thermally insulated from the head body 21. As a result, the optical fiber focusing portions 61 a and 62 a are less susceptible to thermal effects from the head body 21.

The control device 70 controls the heating mechanism 30 h, the power supply 51, the matching circuit unit 52, the flow meter 41, the distance between the substrate support 30 and the shower plate 22, and the like. Further, the temperature of the substrate mounting surface 30s, the temperature of the shower plate 22 measured by the temperature measuring device 60, and the pressure in the vacuum vessel 10 measured by the pressure gauge 13 are sent to the control device 70. The temperature of the substrate mounting surface 30s is sampled at a cycle of 0.1 seconds.

The controller 70 generates plasma between the substrate support 30 and the shower plate 22. For example, the control device 70 controls the flow meter 41 to inject a process gas from the shower plate 22 toward the substrate support 30. The controller 70 controls the power supply 51 and the matching circuit unit 52 to generate plasma between the substrate support 30 and the shower plate 22.

The plasma includes a preliminary discharge plasma (first plasma) under the preliminary discharge condition (first discharge condition) and a treatment plasma (second plasma) under the plasma treatment condition (second discharge condition). The predischarge plasma may be different or the same as the plasma processing conditions. In this embodiment, the case where the preliminary discharge plasma and the plasma processing conditions are different is illustrated. The shower plate 22 having no heating mechanism is heated by the preliminary discharge plasma or the treatment plasma. Furthermore, the shower plate 22 is indirectly heated by the radiant heat emitted from the substrate support 30, or the gas existing between the shower plate 22 and the substrate support 30 is heated as a heat medium.

In the plasma processing method using the plasma processing apparatus 1, the substrate mounting surface 30 s of the substrate support 30 is previously set to the first temperature. Next, the temperature of the shower plate 22 is set to a temperature (second temperature) higher than the temperature at which the shower plate 22 is heated by the heat of the substrate support 30 by the heat and the preliminary discharge plasma of the substrate support 30. Ru. Thereafter, the substrate 80 is plasma-treated while the shower plate 22 is heated by the heat and the processing plasma of the substrate support 30. The controller 70 may issue a warning when the temperature of the shower plate 22 exceeds a desired processing temperature, and may interrupt or cancel the plasma processing.

Hereinafter, a plasma processing method using the plasma processing apparatus 1 will be described taking plasma CVD as an example. As a raw material gas for film formation, for example, TEOS (tetraethylene orthosilicate) is used. The film formed on the substrate 80 is, for example, a silicon oxide film. As the source gas, an organic silicon gas other than TEOS, silane, disilane or the like may be used. The film formed on the substrate 80 may be a silicon nitride film, an amorphous silicon film or the like.

Plasma CVD utilizes a chemical reaction on substrate 80 to form a film on substrate 80. For this reason, the substrate temperature at the time of film formation greatly affects the film formation rate.

At the time of film formation, the reaction on the surface of the substrate proceeds while the precursor molecules are adsorbed to the substrate 80. For this reason, if the temperature of the substrate 80 changes during film formation, the film formation rate may fluctuate. In the plasma processing apparatus 1, the substrate temperature is heated with high accuracy by the heating mechanism 30h in order to suppress the fluctuation of the film forming rate due to the substrate temperature.

However, in plasma CVD, in addition to the substrate temperature, the temperature of the shower plate 22 also affects the deposition rate.

For example, when TEOS gas is used as a process gas, TEOS is a liquid at normal temperature, and is therefore introduced into the vacuum vessel 10 after being vaporized beforehand by a vaporizer (not shown) before reaching the flowmeter 41. Ru. The TEOS gas is used, for example, as a source gas for forming a gate insulating film of a thin film transistor.

When using a raw material gas such as TEOS gas having a molecular weight larger than that of an inorganic silicon-based gas (e.g., SiH ₄ ) and vaporizing a liquid, the deposition rate is not only the substrate temperature but also the temperature of the shower plate 22. to be influenced. For example, as the temperature of the shower plate 22 decreases, TEOS is more easily adsorbed on the inner wall of the shower head 20 or in the gas injection holes 23, and the amount of TEOS directed from the shower head 20 toward the substrate 80 decreases.

That is, even if the temperature of the substrate 80 is kept constant, if the temperature of the shower plate 22 changes during film formation, the amount of TEOS ejected from the shower plate 22 changes. For example, as the temperature of the shower plate 22 decreases and the amount of TEOS ejected from the shower plate 22 decreases, the concentration of TEOS reaching the substrate 80 decreases. As a result, the film forming speed is reduced. For this reason, in order to maintain a stable deposition rate, it is important to control not only the substrate temperature but also the temperature of the shower plate 22 at a constant level.

In the present embodiment, while the temperature of the shower plate 22 is monitored by the temperature measuring device 60, the shower plate 22 is heated by the heat of the substrate support 30 and the plasma generated in the vacuum vessel 10.

Further, in the plasma CVD, before the substrate 80 is carried into the vacuum vessel 10, a process called so-called "pre-film formation" may be performed. In the pre-film formation, a film to be formed on the substrate 80 is formed on the inner wall of the vacuum vessel 10, the surface of the member in the vacuum vessel 10, the surface of the shower plate 22, etc. using the same or different plasma as the processing plasma at the time of film formation. Do. By performing the pre-deposition, immediately after the start of the deposition, the inner wall of the vacuum vessel 10, the surface of the member in the vacuum vessel 10, the surface of the shower plate 22 etc. is the inner wall of the vacuum vessel 10 during deposition The surface of the member, the surface of the shower plate 22, etc. become the same, and the processing plasma becomes stable immediately after the start of film formation.

By the pre-deposition, the temperature of the shower plate 22 is heated to a predetermined temperature before the start of the deposition by the heat of the substrate support 30 and the plasma at the pre-deposition. However, since the pre-deposition is a pre-treatment before the start of the deposition, the processing time is limited. For example, silicon oxide of excessive thickness is deposited on the inner wall of the vacuum vessel 10, the surface of the member in the vacuum vessel 10, the surface of the shower plate 22 and the like as the pre-deposition time lengthens, which causes dust generation. Furthermore, if pre-deposition is performed until the temperature of the shower plate 22 is saturated, the time required for pre-deposition becomes long and productivity decreases. Therefore, the pre-deposition time is limited, and the shower plate 22 may not be sufficiently heated by the heat of the substrate support 30 and the plasma during the pre-deposition alone.

When film formation is started without sufficiently heating the temperature of the shower plate 22, the vacuum vessel 10 is heated by the heat of the substrate support 30 and the processing plasma at the time of film formation each time the substrate 80 is subjected to film formation processing. The surface temperature of the inner wall, the members in the vacuum vessel 10, and the shower plate 22 rises. Therefore, even if the film forming conditions other than the shower plate temperature are the same, the film forming speed changes every time the film forming process is repeated. In such a case, the thickness of the film formed on the substrate 80 will vary with each film formation process.

Further, in the plasma CVD, after the film forming process, the inside of the vacuum container 10 may be cleaned by introducing fluorine ions, fluorine radicals or the like obtained by decomposing a fluorine-based gas (NF ₃ or the like) into the vacuum container 10.

In the cleaning process, since the plasma is not generated in the vacuum vessel 10, the shower plate 22 is exposed to the cleaning gas. Thereby, the temperature of the shower plate 22 is rapidly cooled. Thereafter, even if the shower plate 22 is heated again by the pre-film formation, the shower plate 22 rapidly cooled by the cleaning gas is not sufficiently heated, and the film formation process is started as it is. As a result, the thickness of the film formed on the substrate 80 varies from film formation process to film formation process.

On the other hand, in the present embodiment, in order to compensate for the insufficient heating at the time of pre-deposition, a heating plasma in which an inert gas, nitrogen gas, or the like is discharged is used before the start of the deposition. Furthermore, in the present embodiment, the temperature of the shower plate 22 is monitored in a noncontact manner. For example, the temperature of the shower plate 22 is monitored by the temperature measuring device 60 at the time of pre-deposition, at the time of generation of heating plasma, at the time of deposition, and at the time of cleaning.

A specific example of the plasma processing method according to the present embodiment will be described below.

2 (a) and 2 (b) are schematic graphs showing the relationship between the process time and the temperature of the shower plate according to the present embodiment. FIG.2 (b) is the graph to which P1 area of FIG. 2 (a) was expanded.

For example, in section A, the plasma processing apparatus 1 is in a state before the film formation start. Section A is an idle state of the plasma processing apparatus 1. For example, in a state where the substrate 80 is not supported on the substrate support 30, the substrate support 30 is set to a temperature (first temperature) in the range of 60 ° C. or more and 500 ° C. or less by the heating mechanism 30h. The first temperature is, for example, 380.degree. The shower plate 22 is heated by the heat which the substrate support 30 has, and is set to, for example, 330.degree. Even after the section A, the temperature of the substrate support 30 is maintained at the first temperature.

Next, in section B1, in a state where the substrate 80 is not supported on the substrate support 30, the preliminary discharge plasma is generated between the substrate support 30 and the shower plate 22 under the preliminary discharge condition. Here, the preliminary discharge plasma includes plasma at the time of pre-deposition and plasma for heating. In the section A-section B, the substrate may be supported on the substrate support 30. The substrate in this case is, for example, a dummy substrate or the like.

For example, in section B1, pre-deposition is performed for 200 seconds in advance. The conditions for the pre-film formation are, for example, the same as the film formation conditions except for the film formation time and the temperature of the shower plate 22. In the pre-film formation, a silicon oxide film adheres to the inner wall of the vacuum vessel 10, the gas injection surface 22s of the shower plate 22, the surface of the substrate support 30, and the like. For example, a silicon oxide film having a thickness of 300 nm is attached to the substrate mounting surface 30s. By pre-filming, for example, the temperature of the shower plate 22 is raised by 5 ° C., and the temperature of the shower plate 22 is set to 335 ° C.

Next, a heating plasma is generated by nitrogen plasma, and the shower plate 22 is heated by the heating plasma. An example of the condition of nitrogen plasma is N ₂ flow rate: 5 slm, pressure: 300 Pa, distance between the substrate support 30 and the shower plate 22: 20 mm, discharge power: 10 KW.

Thus, in section B1, the shower plate 22 is heated by the heat of the substrate support 30, the plasma at the time of pre-deposition, and the heating plasma, and the temperature of the shower plate 22 is even higher than 335.degree. Set to Here, with the second temperature (T2) in the first embodiment, when the film formation processing is performed on one substrate 80, the heat that the shower plate 22 has in the substrate support 30, and the processing plasma at the time of film formation Is heated to saturate the temperature of the shower plate 22. In other words, it is a temperature at which the temperature of the shower plate 22 becomes maximum during the period in which the film formation processing of one substrate 80 is performed. In the example of FIG. 2 (a), (b), 2nd temperature (T2) is 358 degreeC. In the embodiment, this temperature is called saturation temperature.

Furthermore, in section B1, the temperature of the shower plate 22 is monitored by the temperature measuring device 60. When the temperature of the shower plate 22 reaches the second temperature (T2), the heating plasma is automatically extinguished. That is, the process in the section B1 is a process of setting the temperature of the shower plate 22 to the second temperature (T2), and the preliminary discharge conditions are adjusted based on the shower plate temperature. After the heating plasma is extinguished, the temperature of the shower plate 22 naturally cools and drops to a third temperature (T3) lower than the second temperature (T2).

Next, in section C, the substrate 80 on the substrate support 30 is placed, and a process gas (for example, TEOS) is injected from the shower plate 22 toward the substrate support 30. Further, processing plasma at the time of film formation is generated between the substrate support 30 and the shower plate 22 to perform film formation on the substrate 80 on the substrate support 30.

In the section C, a film forming process is performed on a plurality of substrates 80 one by one. In the present embodiment, this is referred to as a “film forming cycle”. For example, in the examples of FIGS. 2A and 2B, the film forming process is performed on a total of seven substrates 80 as one film forming cycle. In one film forming cycle, film forming processing is performed on the seven substrates 80 one by one under the same film forming conditions.

In section C, the temperature of the shower plate 22 is changed from the third temperature (T3) to the second temperature by the heat of the substrate support 30 and the processing plasma at the time of film formation each time a film formation process is performed on one substrate 80. Ascend to (T2). Here, the temperature of the shower plate 22 at the time of film formation does not exceed the second temperature (T2). This is because the second temperature (T2) is a temperature at which the temperature of the shower plate 22 becomes maximum at the time of film formation.

In the film forming cycle, after the film forming process on one substrate 80 is completed, the processing plasma is stopped and the film forming process is ended. Thereby, the temperature of the shower plate 22 falls to the third temperature (T3). Subsequently, the next substrate 80 is supported on the substrate mounting surface 30s, and the film formation process is performed on the next substrate 80 as well. Thereby, the temperature of the shower plate 22 changes from the third temperature (T3) to the second temperature (T2) again. This repetition is performed on a total of seven substrates 80. In other words, in the film forming cycle, the temperature fluctuation of raising and lowering the temperature of the shower plate 22 between the third temperature (T3) and the second temperature (T2) is repeated seven times. After this, the processing plasma is extinguished.

Next, in section D, a cleaning gas such as fluorine ion or fluorine radical is introduced into the vacuum vessel 10. Thus, the inner wall of the vacuum vessel 10, the gas injection surface 22s of the shower plate 22, the surface of the substrate support 30, etc. are cleaned. For example, the silicon oxide film deposited on the inner wall of the vacuum vessel 10, the gas injection surface 22s of the shower plate 22, the surface of the substrate support 30, etc. is removed. At this time, the shower plate 22 exposed to the cleaning gas is rapidly cooled to a temperature lower than the third temperature.

Next, in section B2, in a state where the substrate 80 is not supported on the substrate support 30, until the temperature of the shower plate 22 reaches the second temperature (T2) by the heat of the substrate support 30 and the preliminary discharge plasma. The shower plate 22 is heated again. After this, the film forming cycle of section C is performed again.

By the above plasma processing method, even if one film forming cycle is repeated a plurality of times, the film forming conditions for each substrate 80 in each film forming cycle become the same, and the film forming speed when forming a film on each substrate 80 And the thickness of the film formed on each substrate 80 is less likely to vary.

Next, plasma processing according to a comparative example will be described.

FIG. 3A and FIG. 3B are schematic graphs showing the relationship between the process time and the temperature of the shower plate according to the comparative example. FIG.3 (b) is the graph to which P1 area of FIG. 3 (a) was expanded.

Also in the comparative example, in the section A, the substrate support 30 is set to the first temperature (T1). After the section A, the temperature of the substrate support 30 is maintained at the first temperature.

Next, in section B1, a preliminary discharge plasma is generated. The preliminary discharge plasma of the comparative example is a plasma only for the pre-film formation, or a plasma and a heating plasma for the pre-film formation. However, the generation time of the heating plasma in the comparative example is assumed to be shorter than this embodiment. Therefore, in the comparative example, the film formation is started in a state where the temperature of the shower plate 22 does not reach the second temperature (T2).

Thereby, in the comparative example, in section C, even if the shower plate 22 is heated by the heat of the substrate support 30 and the processing plasma at the time of film formation, the temperature of the shower plate 22 is the second temperature in the film forming cycle. It becomes difficult to reach (T2). For example, in the example of FIGS. 3A and 3B, the temperature of the shower plate 22 rises stepwise in each film forming process in the film forming cycle, and the shower plate 22 is further formed every time the film forming cycle is repeated. The temperature rises relatively. In the comparative example, the temperature of the shower plate 22 becomes the second temperature (T2) when the film forming process is performed on the last substrate 80 in the fourth film forming cycle.

Therefore, in the comparative example, the film forming conditions for each substrate 80 in each film forming cycle are different, and the film forming speed when forming a film on each substrate 80 and the thickness of the film formed on each substrate 80 vary.

FIG. 4A is a schematic graph showing the relationship between the process time and the deposition rate according to the present embodiment. FIG. 4B is a schematic graph showing the relationship between the process time and the deposition rate according to the comparative example.

As shown in FIG. 4A, in the present embodiment, in each film forming cycle, the film forming rate when forming a film on each substrate 80 is stable. On the other hand, in the comparative example shown in FIG. 4B, in each film forming cycle, the film forming rate at the time of film formation on each substrate 80 is gradually increasing. Furthermore, in the comparative example, the film forming speed when forming a film on each substrate 80 is relatively increased each time the film forming cycle is repeated.

As described above, in the present embodiment, the temperature of the shower plate 22 is set by the preliminary discharge plasma before the film forming cycle is started in order to suppress the variation in the film forming rate when forming the film on each substrate 80. Is raised to the second temperature (T2).

As a result, since the temperature of the shower plate 22 reaches the second temperature (T2) which is the maximum temperature immediately after the film forming cycle, the temperature of the shower plate 22 hardly varies in each film forming cycle. As a result, the film forming rate when forming a film on each substrate 80 and the thickness of the film formed on each substrate 80 are less likely to vary.

Furthermore, in the present embodiment, the shower plate 22 is not provided with a heater mechanism. Thus, when the shower plate 22 is cleaned, it is not necessary to remove the heater from the shower plate 22. If a heater is provided in the shower plate 22, temperature spots may occur in the shower plate 22 depending on the vicinity of the heater and the distance from the heater, but such a risk does not occur.

Further, in the present embodiment, the temperature of the shower plate 22 is measured without contact. For example, the temperature of the shower plate 22 is measured by a temperature measuring device 60 disposed outside the vacuum vessel 10 on the back side of the shower plate 22. As a result, the temperature measurement device 60 does not come in contact with the shower plate 22, and the installation of the temperature measurement device 60 does not cause the temperature unevenness of the shower plate 22.

Further, since the temperature of the shower plate 22 is directly measured by the temperature measuring device 60, it is not necessary to investigate the relationship between the temperature of the shower plate 22 and the discharge conditions by trial and error, and it is not necessary to carry out prior experiments or simulations. .

When the temperature of the shower plate 22 reaches the second temperature (T2) only by the pre-deposition, it is not necessary to generate the heating plasma, and the deposition cycle may be started after the pre-deposition.

Second Embodiment

In the second embodiment, the second temperature (T2) is not set to the saturation temperature of the shower plate 22, but is set to a temperature higher than the first temperature (T1) and equal to or less than the saturation temperature. In the second embodiment, the film forming cycle is started when the temperature of the shower plate 22 is lower than the saturation temperature. In this case, the temperature of the shower plate 22 may vary for each film forming process, and the film forming rate may vary. However, the variation in film thickness can be suppressed by grasping the relationship between the temperature of the shower plate 22 and the deposition rate before the deposition process.

FIG. 5 is a schematic graph showing the relationship between shower plate temperature and deposition rate.

As shown in FIG. 5, as the temperature of the shower plate 22 rises, the deposition rate becomes faster. The reason is as described above. Here, the film forming conditions other than the shower plate temperature are the same. As a result, even if the temperature of the shower plate 22 is different for each film forming process, the thickness of the film formed on the substrate 80 can be controlled by controlling the film forming time according to the temperature of the shower plate 22. means.

FIG. 6A is a schematic graph showing the relationship between the process time and the deposition rate according to the present embodiment. FIG. 6 (b) is a schematic graph showing the relationship between the process time and the film thickness according to the present embodiment.

In the example of FIG. 6A, in the film forming cycle, the film forming speed is increased for each film forming process. This is because the temperature of the shower plate 22 rises for each film forming process.

However, even in such a case, in each film forming cycle, the film forming rate for each film forming process is determined from the calibration curve (FIG. 5), and each substrate 80 is calculated by calculating the film forming time from the determined film forming rate. Films of the same thickness can be formed.

For example, in each film forming cycle, when the temperature of the shower plate 22 rises for each film forming process and the film forming rate rises, the film forming time is increased each time the number of film forming processes increases in each film forming cycle. shorten. Thus, the film thickness of each substrate 80 in each film forming cycle becomes uniform (FIG. 6B).

Furthermore, in each film forming cycle, the temperature of the shower plate 22 may fluctuate due to an unexpected event. For example, the temperature of the shower plate 22 may fluctuate due to a change in processing time for each substrate 80, an increase in the interval at which the substrates are transported to the transport chamber, or an unstable output of the heating mechanism 30h. There is. Even in such a case, the film forming speed for each film forming process is determined from the calibration curve (FIG. 5), and the film forming time is calculated from the film forming rate determined to form a film of the same thickness on each substrate 80 be able to.

In addition to the film forming time, according to the temperature of the shower plate 22, at least a film forming condition parameter such as a discharge power, a flow rate of reaction gas, a distance between the shower plate 22 and the substrate support 30, and a film forming pressure. Varying one can form a film of the same thickness on each substrate 80.

An example of film formation condition parameters is shown below. The following film forming conditions are also an example of the film forming conditions (section C) of the first embodiment.

Film: TEOS silicon oxide film Source gas (gas flow rate): TEOS (0.1 slm or more and ₂ slm or less), O ₂ ( ₂ slm or more and 60 slm or less)
Discharge power: 0.5 kW or more and 17 kW or less Distance between shower plate and substrate support: 15 mm or more and 35 mm or less Deposition pressure: 50 Pa or more and 400 Pa or less

Film: Silicon oxide film Source gas (gas flow rate): SiH ₄ (0.1 slm or more and 5 slm or less), N ₂ O ( ₂ slm or more and 60 slm or less), Ar (2 slm or more and 60 slm or less)
Discharge power: 0.5 kW or more and 17 kW or less Distance between shower plate and substrate support: 15 mm or more and 35 mm or less Deposition pressure: 50 Pa or more and 400 Pa or less

Film: Amorphous silicon film Source gas (gas flow rate): SiH ₄ (0.1 slm or more and 3 slm or less), Ar (2 slm or more and 60 slm or less)
Discharge power: 0.1 kW or more and 5 kW or less Distance between shower plate and substrate support: 15 mm or more and 35 mm or less Pressure during film formation: 50 Pa or more and 400 Pa or less

Film: Silicon nitride film Raw material gas (gas flow rate): SiH ₄ (0.1 slm to 5 slm), NH ₃ ( ₂ slm to 60 slm), N ₂ ( ₂ slm to 60 slm),
Discharge power: 0.5 kW or more and 17 kW or less Distance between shower plate and substrate support: 15 mm or more and 35 mm or less Deposition pressure: 50 Pa or more and 400 Pa or less

For example, when the temperature of the shower plate 22 falls within a range of ± 10 ° C. based on a temperature (eg, 348 ° C.) lower by 10 ° C. than the saturation temperature (eg, 358 ° C.) The film thickness can be controlled by adjustment. For example, when the temperature of the shower plate 22 is relatively low in the above range, the deposition speed can be increased by increasing the discharge power. Conversely, when the temperature of the shower plate 22 is relatively high in the above range, the deposition rate can be reduced by reducing the discharge power. Thereby, a film of the same thickness can be formed on each substrate 80.

In addition, when the temperature of the shower plate 22 falls within a range of ± 10 ° C. based on a temperature (eg, 348 ° C.) lower by 10 ° C. than the saturation temperature during film formation, film thickness control by adjusting the gas flow rate Is possible. For example, when the temperature of the shower plate 22 is relatively low in the above range, the deposition rate can be increased by increasing the gas flow rate. Conversely, when the temperature of the shower plate 22 is relatively high in the above range, the deposition rate can be reduced by reducing the gas flow rate. Thereby, a film of the same thickness can be formed on each substrate 80.

In addition to the control of film thickness, control of film quality is also possible. For example, if the temperature of the shower plate 22 falls within a range of ± 10 ° C. based on a temperature (eg, 348 ° C.) lower by 10 ° C. than the saturation temperature during the film forming process, adjustment of the film quality can be performed by adjusting the discharge power. It is possible.

For example, in the case of forming a silicon nitride film on the substrate 80, if the temperature of the shower plate 22 is relatively low within the above range, the film density will be low if the film formation is performed in this state. In this case, the film density can be returned to a predetermined range by increasing the discharge power. Conversely, if the film formation is performed with the temperature of the shower plate 22 relatively high in the above range, the film density will be high. In that case, the film density can be returned to a predetermined range by reducing the discharge power.

On the other hand, when the silicon oxide film is formed on the substrate 80, if the temperature of the shower plate 22 is relatively low within the above range, the film density will be high if the film formation is performed in this state. In this case, the film density can be returned to a predetermined range by reducing the discharge power.

Thereby, a film of the same film quality can be formed on each substrate 80.

When the temperature of the shower plate 22 overshoots beyond the saturation temperature due to abnormal discharge or the like, the temperature of the shower plate 22 can be lowered by introducing a cooling gas into the shower plate 22. For example, when the temperature of the shower plate 22 becomes 10 ° C. or more higher than the saturation temperature, a cooling gas is introduced into the shower plate 22 to cool the shower plate 22 to the saturation temperature. Here, the cooling gas is at least one gas such as N ₂ , Ar, H ₂ , He or the like.

As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, of course, a various change can be added.

For example, in the sections B1 and B2, after the heating plasma is generated, pre-film formation may be performed. Thus, after the silicon oxide film adheres to the inner wall of the vacuum vessel 10, the gas injection surface 22s of the shower plate 22, the surface of the substrate support 30, etc., these surfaces etc. are not heated but these surfaces etc. After heating, a silicon oxide film adheres to these surfaces and the like. Thereby, peeling (dust generation) of the silicon oxide film from these surfaces etc. is suppressed.

Further, when the plasma processing apparatus 1 is applied to dry etching, the temperature of the shower plate 22 is adjusted to a temperature at which the temperature of the shower plate 22 becomes maximum at the time of the etching process before starting the etching cycle. After that, it goes without saying that if the etching cycle is started, the same etching rate can be obtained for each etching process in each etching cycle.

DESCRIPTION OF SYMBOLS 1 ... Plasma processing apparatus 10 ... Vacuum container 10h ... Gas exhaust port 10p ... Plasma formation space 11 ... Support part 12 ... Lid part 13 ... Pressure gauge 15 ... Space 20 ... Shower head 21 ... Head main body 21h ... Hole part 22 ... Shower plate 22s: gas ejection surface 22r: back surface 23: gas ejection port 25, 26: transparent window material 27: insulating member 28: internal space 30: substrate support base 30s: substrate mounting surface 30h: heating mechanism 31: capacity 40: gas supply Source 41: Flow meter 42: Gas introduction pipe 50, 55: Power supply source 51: Power supply 52: Matching circuit unit 53: Wiring 60: Temperature measurement device 61: First radiation thermometer 61a: Optical fiber focusing unit 61b: Main body Part 62 ... second radiation thermometer 62a ... optical fiber condensing part 62b ... main part 65 ... fixing jig 70 ... control device 80 ... substrate

Claims (7)

Heating the substrate support disposed in the vacuum chamber to a first temperature;
A first plasma under a first discharge condition is generated between the substrate support and the shower plate facing the substrate support, and the shower plate is heated by the heat of the substrate support and the first plasma. ,
Non-contact monitoring of the temperature of the shower plate,
After the temperature of the shower plate reaches a second temperature higher than the temperature heated by the heat of the substrate support, a process gas is injected from the shower plate toward the substrate support, and the substrate support is And generating a second plasma under a second discharge condition between the first and second shower plates, and processing the substrate supported on the substrate support by the second plasma. The plasma processing method according to claim 1,
The plasma processing method, wherein in the step of processing the substrate, the second temperature is a temperature at which the temperature of the shower plate becomes maximum in the step of processing the substrate. The plasma processing method according to claim 1,
In the process of the plasma processing, the second discharge condition includes a discharge power, a flow rate of reaction gas, and a processing time, the substrate is processed every plural sheets, and the second temperature changes every time the substrate is processed. At the time, a plasma processing method of processing the substrate by changing at least one of the discharge power, the flow rate of the reaction gas, and the processing time according to the value of the second temperature. The plasma processing method according to any one of claims 1 to 3, further comprising
In the plasma processing step, a plurality of the substrates are processed, and the plurality of substrates are processed, and then a cleaning gas is ejected to the vacuum container to clean the inside of the vacuum container. The plasma processing method according to any one of claims 1 to 4, wherein
The plasma processing method which monitors the temperature of the said shower plate by the radiation thermometer arrange | positioned out of the said vacuum vessel at the back side of the said shower plate. The plasma processing method according to any one of claims 1 to 5, wherein
The second discharge condition is a plasma processing method different from the first discharge condition. A vacuum vessel in which the reduced pressure is maintained;
It is disposed in the vacuum vessel, has a substrate mounting surface and a heating mechanism, can set the substrate mounting surface to a first temperature by the heating mechanism, and can support the substrate. A substrate support,
A shower plate facing the substrate support;
A power supply for generating plasma between the substrate support and the shower plate;
A temperature measuring device for measuring the temperature of the shower plate without contact;
The temperature measurement device monitors the temperature of the shower plate, generates a first plasma under a first discharge condition between the substrate support and the shower plate, and the heat and the substrate support have. After the shower plate is heated by plasma and the temperature of the shower plate reaches a second temperature higher than the temperature heated by the heat of the substrate support, the shower plate is directed to the substrate support. A control device capable of processing the substrate by the second plasma by injecting a process gas and generating a second plasma under a second discharge condition between the substrate support and the shower plate; Plasma processing equipment.

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