JP2012012634A - Plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent warpage and distortion of a cathode electrode in a plasma CVD processing apparatus.SOLUTION: A plasma CVD apparatus 100 for processing a substrate by generating plasma of a processing gas is provided with a processing container 103 for receiving the substrate, and a cathode electrode 101 and an anode electrode 102 which are arranged in the processing container 103. The cathode electrode 101 includes a backing plate 3 and a shower plate 2 which form a buffer chamber 4 between them. A middle fastening portion 6 and a periphery fastening portion 7 which come into contact with the backing plate 3 are formed in the shower plate 2, and the ratio of the heat capacity of the shower plate 2 to that of the backing plate 3 is 1/2 or more. Therefore, a transient change of the temperature difference between the shower plate 2 and the backing plate 3 is suppressed at the time of plasma generation, thereby suppressing the warpage and distortion of the cathode electrode 101.

Description

  The present invention relates to a plasma processing apparatus for processing a substrate by converting a processing gas into plasma.

  Conventionally, for example, a plasma CVD (plasma-enhanced chemical vapor deposition) apparatus using a microwave or a high frequency is used in a film forming process or an etching process.

  For example, a plasma CVD apparatus for forming a thin film on a substrate includes a cathode electrode connected to a high-frequency power source and a gas introduction system, and an anode electrode that supports the substrate so as to face the cathode electrode. The cathode electrode also functions as a processing gas supply member for supplying a processing gas from the gas introduction system into the processing chamber. When a high frequency voltage is applied to both electrodes, plasma generated between the pair of electrodes activates the processing gas, and this activated processing gas reaches the substrate on the anode electrode to form a thin film. At this time, the temperature of the plasma generation region rises to a high temperature.

  In general, an electrode functioning as a processing gas supply member includes a shower plate having a through hole for supplying a processing gas and a support plate disposed on the back surface of the shower plate. If the shower plate is deformed by the heat of the plasma when the plasma is generated, a uniform thin film cannot be formed.

  Therefore, Patent Document 1 discloses a technique for suppressing a temperature rise of an upper electrode that supplies a processing gas among a pair of electrodes in a plasma CVD apparatus. Specifically, of the pair of electrodes, the upper electrode for supplying the processing gas is disposed between the two plates, the temperature adjustment plate having a cooling water channel, the gas ejection plate having the ejection hole for ejecting the processing gas, and the two plates. And a heat transfer member. In this configuration, the heat from the plasma is transmitted from the gas ejection plate to the temperature adjustment plate via the heat transfer member, so that the temperature rise of the gas ejection plate is suppressed.

  By the way, in a recently proposed plasma CVD apparatus having a multi-electrode structure, a plurality of pairs of electrodes are arranged in one chamber in order to simultaneously process a plurality of substrates. In such a configuration, each electrode of the pair of electrodes exposes the surface facing each other and the surface opposite to the surface, that is, the front and back surfaces, in the gas phase in the processing chamber. The gas phase means a processing gas atmosphere or a vacuum atmosphere.

Japanese Patent Laid-Open No. 10-30185 (published February 3, 1998)

  The present inventors relate to a plasma CVD apparatus in which a cathode electrode for supplying a processing gas is exposed to a gas phase in a chamber, by a transient temperature difference between a shower plate and a support plate constituting the cathode electrode. It has been found that there is a case where the thin film forming process cannot be stably performed.

  That is, in the plasma CVD apparatus in which the cathode electrode is exposed to the gas phase in the chamber, the shower plate facing the plasma generation region is easily affected by the heat of the plasma, while the support plate is not in contact with the discharge surface. It is susceptible to controlled temperatures on chamber walls and other sets of anode electrodes. For this reason, the temperature of the shower plate rises immediately after the start of plasma generation, while the temperature of the support plate gradually rises by receiving heat from the shower plate. Therefore, since the temperature difference between the shower plate and the support plate once increases rapidly and then gradually decreases, the transient temperature difference increases and it takes time to stabilize.

  Such a change in the temperature difference between the shower plate and the support plate causes a transient warp or distortion of the cathode electrode, making it difficult to perform a stable thin film forming process.

  However, the technique disclosed in Patent Document 1 has not been studied for a plasma CVD apparatus in which the cathode electrode is exposed to the gas phase in the chamber. That is, in the technique disclosed in Patent Document 1, although the upper electrode includes two plates, the temperature difference between the two plates is not taken into consideration at all.

  Furthermore, in Patent Document 1, since one plate has a temperature adjusting means such as a cooling water channel, the thickness of the plate increases, making it unsuitable as a plate constituting the cathode electrode exposed to the gas phase. It is.

  Therefore, the present invention has been made in view of the above problems, and its purpose is to stabilize the temperature difference between the shower plate and the backing plate at an early stage, thereby preventing transient warping and distortion of the electrode. An object of the present invention is to provide a plasma processing apparatus capable of suppressing and stably forming a thin film.

  A plasma processing apparatus for forming a film on a substrate by converting a processing gas into a plasma in a processing chamber, wherein the front and back surfaces of the processing chamber are exposed to a gas phase and are opposed to each other, and between each other. In which the processing gas is converted into plasma, and at least one electrode of the electrode pair sandwiches the first plate disposed on the side facing the counterpart electrode forming a pair, and the first plate The second plate disposed on the opposite side of the electrode and at least one fastening portion for connecting the first and second plates to each other, the first plate with respect to the heat capacity of the second plate. The heat capacity ratio of the plate is characterized by being 1/2 or more.

  In the above configuration, the electrode pair converts the processing gas released into the processing chamber into plasma between the electrodes facing each other. Each electrode exposes the mutually opposing surface and the opposite surface to the gas phase in the processing chamber. Therefore, the surfaces of the electrodes facing each other face a plasma generation region in which the processing gas is converted into plasma.

  In the above configuration, at least one of the electrode pairs is configured by two plates connected to each other by a fastening portion. The two plates are in partial contact with each other through the fastening portion. Of the two plates, the first plate faces the plasma generation region by the processing gas, but the second plate does not face the plasma generation region.

  According to the above configuration, the heat of the plasma during the thin film processing is first transmitted to the first plate facing the plasma generation region. Next, the heat transferred to the first plate is transferred to the second plate via the fastening portion.

  Here, the ratio of the heat capacity of the first plate to the heat capacity of the second plate is 1/2 or more. For this reason, when plasma is generated, the temperature difference between the first plate and the second plate does not proceed more rapidly than the temperature transfer from the first plate to the second plate. Stabilizes early at low values.

  Therefore, since the temperature difference between the two plates constituting the electrode is suppressed, warping, distortion, and the like of the electrode are suppressed. For this reason, according to the plasma processing apparatus concerning this invention, thin film formation can be implemented stably.

  In the plasma processing apparatus according to the present invention, the ratio of the heat capacity of the first plate to the heat capacity of the second plate is preferably 1 or more.

  According to the above configuration, since the generation of a large peak is suppressed with respect to the temperature difference between the two plates constituting the electrode after the start of plasma generation, the warpage or distortion of the electrode is more effectively suppressed. be able to.

  In the plasma processing apparatus according to the present invention, the ratio of the heat capacity of the first plate to the heat capacity of the second plate is preferably 3 or less.

  According to the above configuration, when plasma is generated, a change in which the temperature difference between the first plate and the second plate gradually increases is suppressed, and stable processing can be performed even for long-time processing. .

  In the plasma processing apparatus according to the present invention, the first plate is a shower plate having a plurality of through holes for supplying the processing gas between the electrode pairs, and the second plate is the shower plate. It is preferable that it is a support plate which supports a plate.

  In the above configuration, the electrode composed of two plates is connected to, for example, a gas supply system, and the processing gas supplied from the gas supply system is discharged into the processing chamber through the through hole. According to the said structure, the plasma processing apparatus concerning this invention can be comprised suitably.

  In the plasma processing apparatus according to the present invention, the first plate and the second plate are preferably made of the same material.

  According to the said structure, the deformation | transformation resulting from a linear expansion coefficient difference can be prevented about the electrode comprised from two board. Further, for example, by setting the thickness of each plate, it is possible to set the heat capacity of the two sheets in a desirable relationship.

  In the plasma processing apparatus according to the present invention, it is preferable that a plurality of pairs of the electrode pairs are arranged side by side in the processing chamber.

  According to the said structure, the plasma processing apparatus which concerns on this invention can be made into the plasma processing of a multi-electrode structure. In this configuration, warping and distortion of the electrode connected to the gas supply unit in the electrode pair can be suppressed, and thin film formation can be stably performed.

  In the plasma processing apparatus according to the present invention, of the two plates constituting at least one of the pair of electrodes, the first plate in contact with the plasma has a heat capacity ratio with respect to the second plate not in contact with the plasma. Is 1/2 or more. For this reason, at the time of plasma generation, the change of the transient temperature difference between the two plates of at least one of the electrodes is suppressed, and the warpage or distortion of the electrode is suppressed. Therefore, it is possible to provide a plasma processing apparatus capable of stably forming a thin film.

It is sectional drawing which shows partially the cathode electrode of the plasma CVD apparatus which concerns on one Embodiment of this invention. 1 is a cross-sectional view schematically showing a plasma CVD apparatus according to an embodiment of the present invention. It is sectional drawing which shows the gas supply system and gas exhaust system of the plasma CVD apparatus shown in FIG. It is sectional drawing which shows the modification of the plasma CVD apparatus shown in FIG. It is sectional drawing which shows the modification of the plasma CVD apparatus shown in FIG. It is sectional drawing which shows the modification of the plasma CVD apparatus shown in FIG. It is a perspective view which cuts and shows the structure of the cathode electrode which concerns on an Example partially. It is sectional drawing which shows partially the cathode electrode which concerns on a comparative example. It is a perspective view which cuts out and shows the structure of the cathode electrode which concerns on a comparative example partially. It is a graph which shows the relationship between the ratio of the thickness of a shower plate and a backing plate, and the temperature difference of both. It is a graph which shows each temperature of a shower plate and a backing plate, and the temperature difference of both about Example 1 along progress of time. It is a graph which shows each temperature of a shower plate and a backing plate, and the temperature difference of both about Example 2 along progress of time. It is a graph which shows each temperature of a shower plate and a backing plate, and the temperature difference of both about Example 3 along progress of time. It is a graph which shows each temperature of a shower plate and a backing plate about Example 4, and the temperature difference of both along progress of time. It is a graph which shows each temperature of a shower plate and a backing plate, and the temperature difference of both about Example 5 along progress of time. It is a graph which shows each temperature of a shower plate and a backing plate, and the temperature difference of both about the comparative example 1 along progress of time. It is a graph which shows each temperature of a shower plate and a backing plate, and the temperature difference of both about the comparative example 2 along progress of time. About comparative example 6, it is a graph which shows each temperature of a shower plate and a backing plate, and the temperature difference of both along progress of time. It is a graph which shows each temperature of a shower plate and a backing plate and the temperature difference of both about the comparative example 3 along progress of time.

(Configuration of plasma CVD apparatus 100)
An embodiment of the present invention will be described below with reference to FIGS.

  First, a schematic configuration of a plasma CVD apparatus (plasma processing apparatus) 100 according to the present embodiment will be described with reference to FIG.

  FIG. 2 is a cross-sectional view illustrating a schematic configuration of the plasma CVD apparatus 100. As shown in FIG. 2, a sealable processing container (processing chamber) 103 that accommodates a substrate as an object to be processed, and a cathode that is arranged in the processing container 103 and includes a cathode electrode 101 and an anode electrode 102. And an anode electrode pair.

  The processing container 103 is made of, for example, stainless steel and has a configuration that can be evacuated. The inner wall surface of the processing container 103 is covered with a protective film such as alumina, and the processing container 103 is electrically grounded.

  Each of the cathode electrode 101 and the anode electrode 102 has a plate shape and is disposed so as to face each other. A substrate is disposed between the cathode electrode 101 and the anode electrode 102. The substrate is not particularly limited as long as the plasma CVD apparatus 100 is an object to be processed, and examples thereof include a glass substrate.

  In addition, each of the cathode electrode 101 and the anode electrode 102 is supported at both ends by support portions (not shown). Therefore, the cathode electrode 101 and the anode electrode 102 have a structure in which the surfaces facing each other and the opposite surface are exposed to the gas phase in the processing vessel 103.

  Of the cathode-anode electrode pair, the anode electrode 102 serves as a mounting table for mounting the substrate thereon, and is disposed below the pair of cathode electrodes 101. The anode electrode 102 is made of a material having conductivity and heat resistance, such as stainless steel, aluminum alloy, and carbon. The dimension of the anode electrode 102 may be designed to an appropriate value in accordance with the dimension of the substrate.

  Further, the anode electrode 102 incorporates temperature stabilizing means such as a heater and a cooling facility, and the temperature is controlled to room temperature (for example, 25 ° C.) to 300 ° C. by the temperature stabilizing means. For this reason, on the substrate on the anode electrode 102, the temperature rise due to the heat of the generated plasma is controlled, and the film is formed at a uniform temperature.

  On the other hand, the cathode electrode 101 is disposed above the paired anode electrodes 102 and is made of a material such as stainless steel or aluminum alloy. The dimensions of the cathode electrode 101 may be designed to an appropriate value in accordance with the dimensions of the substrate, similarly to the anode electrode 102.

The cathode electrode 101 is connected to an external plasma excitation power source 106. As the plasma excitation power source 106, for example, an RF power source having an output of RF 1 MHz to 60 MHz and a power density of 20 × 10 ⁻⁶ W / mm ^{2 to} 5000 × 10 ⁻⁶ W / mm ² according to the dimensions of the substrate is used.

The cathode electrode 101 is connected to a gas supply system (not shown) that supplies a processing gas. As the processing gas, for example, monosilane (SiH ₄ ) gas or the like can be used. The processing gas introduced into the cathode electrode 101 from the gas supply system is supplied into the processing container 103 from the bottom surface of the cathode electrode 101 toward the substrate on the anode electrode 102.

  Here, FIG. 3 shows the processing gas introduction path (gas supply system) and the exhaust path in this embodiment.

  As shown in FIG. 3, as a process gas introduction path, a gas pipe 108 is connected to the cathode electrode 101, and a flow rate controller (mass flow) 107 is provided in the gas pipe 108.

  The gas pipe 108 is provided with an insulating tube 108b and a metal tube 108b. Specifically, in order to maintain high-frequency insulation, it is preferable to use an insulating tube 108b made of an insulating material such as a fluororesin as the gas pipe 108 in the processing vessel 103. However, in the vicinity of the cathode electrode 101 (at least about 5 cm), it is preferable to use a metal tube 108b in order to suppress dissolution due to heat generated during cleaning and etching due to cleaning. As the metal tube 108b, for example, aluminum or stainless steel, which is the same material as the cathode electrode 101, or ceramic which is an insulating material with higher heat resistance can be used.

  Further, an exhaust pipe is connected to the bottom of the processing vessel 103 as an exhaust path, and an exhaust pump 109 such as a vacuum pump is connected to the tip of the exhaust pipe. The exhaust pump 109 (exhaust device) can appropriately depressurize the atmosphere in the processing container 103, and can be set to, for example, 10 Pa or more and 6000 Pa or less.

  In the plasma CVD apparatus 100 configured as described above, for example, the following operation is performed.

  First, the substrate is carried into the processing container 103 and placed on the anode electrode 102. Next, the exhaust pump 109 is operated, and exhaust is performed from the exhaust pipe, whereby the inside of the processing container 103 is decompressed. In addition, the heater is activated to hold the substrate at a desired temperature through the anode electrode 102.

  Next, the film forming process gas supplied from the gas supply system is filled into the plasma generation region 105, which is the gap between the cathode electrode 101 and the anode electrode 102, via the cathode electrode 101. Further, by the operation of the plasma excitation power source 106, high frequency power is applied between the cathode electrode 101 and the anode electrode 102, whereby an electric field is generated in the plasma generation region 105, and the processing gas is turned into plasma. A film forming process is performed on the substrate by the active species generated when the processing gas is turned into plasma.

  After the film formation process for a predetermined time is performed, the supply of the processing gas into the processing container 103 is stopped, the plasma excitation power source 106 is stopped, and the substrate is unloaded from the processing container 103.

  Through the series of steps described above, the film forming process of the substrate by the plasma CVD apparatus 100 is completed.

(Modification)
In the above description, the configuration in which the cathode-anode electrode pair is disposed horizontally in the processing vessel 103 is described. However, the present invention is not limited to this, and as shown in FIG. The structure arranged vertically may be sufficient.

  2 shows the plasma CVD apparatus 100 having one cathode-anode electrode pair in the processing vessel 103, the present invention is not limited to this, and a plurality of cathode-anodes as shown in FIG. It may be configured as a plasma CVD apparatus 200 having a multi-electrode structure including electrode pairs.

  In the plasma CVD apparatus 200, as shown in FIG. 5, a plurality of pairs of cathode-anode electrodes are arranged in the processing vessel 103 at substantially equal intervals. In FIG. 5, only the uppermost cathode electrode 101 is represented as a connection to the plasma excitation power source 106, but actually, all the cathode electrodes 101 in the processing vessel 103 are connected to the plasma excitation power source 106. Has been. The number of cathode-anode electrode pairs arranged in the processing vessel 103 is not particularly limited, and an arbitrary number of cathode-anode electrode pairs can be arranged.

  Further, the plasma CVD apparatus 200 is not limited to the configuration in which the cathode-anode electrode pair is placed horizontally as in the plasma CVD apparatus 100, and the cathode-anode electrode pair is arranged vertically as shown in FIG. It may be a configured.

(Configuration of cathode electrode 101)
The configuration of the cathode electrode 101 will be described in more detail with reference to FIG.

  As shown in FIG. 1, the cathode electrode 101 includes a shower plate (first plate) 2 and a backing plate (second plate: support plate) 3 so as to have a buffer chamber 4 therein. The shower plate 2 is a plate facing the plasma generation region 105 (see FIG. 2), and the backing plate 3 is a plate arranged on the opposite side of the shower plate 2 with respect to the plasma generation region 105.

  The backing plate 3 is connected to a gas supply system (not shown). Inside the backing plate 3, although not shown, a passage for introducing a processing gas from a connection part with the gas supply system to the buffer chamber 4 is provided. The buffer chamber 4 is connected so that the processing gas generally flows through the cathode electrode 101.

  On the other hand, a plurality of through holes 9 are formed in the shower plate 2 so that the buffer chamber 4 penetrates the inside of the processing container 103 vertically. The processing gas supplied to the buffer chamber 4 is supplied into the processing container 103 through the through hole 9. The processing gas is supplied uniformly to the substrate on the anode electrode 102 through the buffer chamber 4 and the through hole 9.

  Further, the shower plate 2 has a plurality of intermediate fastening portions 6 and outer peripheral fastening portions 7 formed on the surface facing the backing plate 3. The shower plate 2 is in contact with the backing plate 3 via the intermediate fastening portion 6 and the outer periphery fastening portion 7 and fastened by screws 5.

  The intermediate fastening portion 6 is a rib formed intermittently in the buffer chamber 4. The shape of the intermediate | middle fastening part 6 is not specifically limited, For example, columnar shapes, such as a prism and a cylinder, can be mentioned. The number of intermediate fastening portions 6 may be one or more, but a plurality of intermediate fastening portions 6 are preferably formed. The outer periphery fastening portion 7 is a rib formed so as to surround the outer periphery of the buffer chamber 4. The presence of the intermediate fastening portion 6 and the outer periphery fastening portion 7 as ribs of the shower plate 2 improves the strength of the shower plate 2, thereby suppressing local distortion.

  Further, the intermediate fastening part 6 and the outer periphery fastening part 7 serve to transmit the heat of the shower plate 2 to the backing plate 3.

  Specifically, when plasma is generated in the plasma CVD apparatus 100, the heat of the plasma is transmitted to the shower plate 2 facing the plasma generation region 105. The heat of the shower plate 2 is further transmitted to the backing plate 3 through the intermediate fastening portion 6 and the outer peripheral fastening portion 7.

  For the heat transfer, it is preferable that the upper surface of the intermediate fastening portion 6 is flat and is in close contact with the backing plate 3. Furthermore, in order to further improve the heat conduction, a heat conduction sheet, grease, or the like may be put in a portion of the intermediate fastening portion 6 where the shower plate 2 and the backing plate 3 are in contact.

  In the present embodiment, the intermediate fastening portion 6 and the outer periphery fastening portion 7 are formed integrally with the shower plate 2, but the present invention is not limited to this, and is formed integrally with the backing plate 3. Also good. From the viewpoint of heat conduction, it is preferable to be integral with either the shower plate 2 or the backing plate 3 as described above, but it is formed separately from either the shower plate 2 or the backing plate 3. Also good.

(Regarding the heat capacity of the cathode electrode 101)
Next, the ratio of the heat capacity between the shower plate 2 and the backing plate 3 constituting the cathode electrode 101 will be described with reference to FIG.

  In addition, each heat capacity of the shower plate 2 and the backing plate 3 changes according to the mass of the object which comprises each plate, or the kind of material.

  So, in this embodiment, after making the material which comprises the shower plate 2 and the backing plate 3 into the same material, the mass is changed by setting the thickness of each plate, and thereby the ratio of the heat capacity between each plate is set. It is set. That is, in the present embodiment, the ratio of the heat capacity and the ratio of the plate thickness are made the same between the shower plate 2 and the backing plate 3.

As shown in FIG. 1, the thickness of the plate shower plate 2 and t _1, the thickness of the plate of the backing plate 3 and t _2. At this time, the thickness of each plate is set so that t ₁ / t _2, which is the ratio of the thickness of the shower plate 2 to the backing plate 3, is ½ or more.

If the thickness ratio t ₁ / t ₂ is smaller than 1/2 as shown in FIG. 8, the temperature of the shower plate 2 rises more rapidly than the temperature of the backing plate 3 immediately after the start of plasma generation. The temperature difference between the shower plate 2 and the backing plate 3 becomes larger. Such a change in temperature difference causes a transient warp or distortion in the shower plate 2, and the thin film processing cannot be performed stably. Moreover, since it takes time until the temperature difference between the shower plate 2 and the backing plate 3 is stabilized, the processing time in an unstable state becomes long.

On the other hand, in the present embodiment, since t ₁ / t ₂ is set to ½ or more, heat conduction through the intermediate fastening portion 6 is effective between the shower plate 2 and the backing plate 3 after the start of plasma generation. Is realized. Therefore, even if the cathode electrode 101 does not include a temperature control device such as a heater, the change can be suppressed so that the temperature difference between the shower plate 2 and the backing plate 3 does not become too large. That is, the temperature difference between the shower plate 2 and the backing plate 3 can be quickly stabilized at a lower value.

  Therefore, in the plasma CVD apparatus 100 according to this embodiment, warpage, distortion, and the like of the cathode electrode 101 after the start of plasma generation are suppressed, so that thin film formation can be performed stably.

The thicknesses of the backing plate 3 and the shower plate 2 are preferably set so that t ₁ / t ₂ is 1 or more. According to the above setting, the occurrence of a peak in the temperature difference between the shower plate 2 and the backing plate 3 after the start of plasma generation in the plasma CVD apparatus 100 is suppressed. As a result, warpage, distortion, and the like of the cathode electrode 101 are more effectively suppressed.

Furthermore, the thicknesses of the backing plate 3 and the shower plate 2 are preferably set so that t ₁ / t ₂ is 3 or less. For example, when t ₁ / t ₂ is larger than 3 when plasma is generated in the plasma CVD apparatus 100, the temperature difference between the shower plate 2 and the backing plate 3 gradually increases. Therefore, according to the above setting, such a change in temperature difference is suppressed, and stable processing can be performed even for processing over a long period of time.

  Moreover, in this embodiment, since the material which comprises the shower plate 2 and the backing plate 3 is comprised from the same material, the deformation | transformation by the thermal expansion difference of the shower plate 2 and the backing plate 3 can also be suppressed. As this material, for example, an aluminum alloy or stainless steel can be used.

  In addition, in this embodiment, although the thickness of each plate of the shower plate 2 and the backing plate 3 is adjusted, this invention is not limited to this. That is, in order to set the ratio of the heat capacity of the shower plate 2 to the backing plate 3, these specific heats may be adjusted by appropriately selecting the material of each plate. For example, stainless steel can be used as the material of the shower plate 2, while carbon or silicon can be used as the material of the backing plate 3. According to the combination of these materials, the material of the shower plate 2 has the same thickness as the material of the backing plate 3 and the heat capacity is about three times as large.

(Thickness of shower plate 2 and backing plate 3)
In the present embodiment, the specific thickness of each of the shower plate 2 and the backing plate 3 is preferably set as follows. However, the present invention is not limited to this. That is, the thickness of each of the shower plate 2 and the backing plate 3 may be set so that the front and back surfaces of the shower plate 2 and the backing plate 3 can be exposed in the gas phase in the processing chamber 103 as long as the ratio described above is satisfied.

The thickness _{t 1} of the shower plate 2 is preferably 3mm or more. For example, during the thin film processing of the plasma CVD apparatus 100, the thin film material adheres not only to the target substrate but also to the surface of the cathode electrode 101 (particularly the shower plate 2). When the number of depositions is increased, the thickness of the film attached to the cathode electrode 101 increases, and the internal stress of this film acts on the cathode electrode 101. Therefore, when the thickness t ₁ of the shower plate 2 is 3 mm or more, the shower plate 2 has sufficient rigidity to cope with the internal stress of the attached film. For this reason, the deformation | transformation by the internal stress of the film | membrane adhering to the shower plate 2 can be prevented.

The thickness t ₂ of the backing plate, on its structure, is preferably 5mm or more.

The height h ₂ of the buffer chamber 4 is preferably 10 to 60% with respect to the height h ₁ of the cathode electrode 101. Thereby, an increase in the total weight of the cathode electrode 101 accompanying the thickness of the shower plate 2 can be suppressed.

  In the present embodiment, the electrode composed of the shower plate 2 and the backing plate 3 is the cathode electrode 101. However, the present invention is not limited to this, and may be the anode electrode 102 or the cathode. Both the electrode 101 and the anode electrode 102 may be used.

  In the present embodiment, the ratio of the heat capacities between the two plates of the shower plate 2 and the backing plate 3 is described, but the present invention is not limited to this. That is, for two plates constituting at least one of the electrodes, the heat capacity of the plate facing the plasma generation region may be ½ or more than the heat capacity of the plate not facing the plasma generation region.

  In addition, a buffer chamber may not be formed between the two plates. For example, when an electrode is configured by combining the two plates, a thermal resistance is generated at the combined portion. In this case, if the heat capacities of the two plates are set as described above, the effects of the present invention can be achieved.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. In other words, embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

  Next, the effects of the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

<When adjusting the thickness of each plate>
First, in Examples 1 to 5, a simulation was performed on the transition of the temperature difference between the shower plate and the backing plate after the start of plasma generation when the plasma CVD apparatus according to the above-described embodiment was used. In Examples 1 to 5, the ratio of the heat capacity of the shower plate to the backing plate was set to ½ or more by adjusting the thickness (t ₁ ) of the shower plate and the thickness (t ₂ ) of the backing plate.

  On the other hand, in Comparative Examples 1 and 2, simulations were performed in the same manner as in Examples 1 to 5 except that the thickness of each plate was adjusted so that the ratio of the heat capacity of the shower plate to the backing plate was less than 1/2. .

  Specifically, the dimensions and ratio t1 / t2 of the shower plate and backing plate were set as shown in Table 1 below, and the other conditions were made common.

  FIG. 7 is a cross-sectional perspective view showing the cathode electrodes according to Examples 1 to 5 partially cut out. As shown in FIG. 7, in Examples 1-5, the temperature measurement part (maximum temperature part H1) of the shower plate and the temperature measurement part (minimum temperature part L1) of the backing plate were set in the cut-out part of the cathode electrode. .

  FIG. 9 is a cross-sectional perspective view showing the cathode electrodes according to Comparative Examples 1 and 2 partially cut out. As shown in FIG. 9, in Comparative Examples 1 and 2, as in Examples 1 to 5, the temperature measurement part (maximum temperature part H2) of the shower plate and the temperature measurement of the backing plate are performed in the portion shown by cutting out the cathode electrode. The site | part (minimum temperature part L2) was set.

  In the simulation, the temperature difference between the highest temperature portion H1 and the lowest temperature portion L1 or the temperature difference between the highest temperature portion H2 and the lowest temperature portion L2 is referred to as a temperature difference between the shower plate and the backing plate (hereinafter simply referred to as a temperature difference). ) Was obtained along the time axis from the start of plasma generation. At the same time, the maximum temperature difference for each example was recorded.

  In addition, about the part shown to FIG. 7 and FIG. 9, four directions other than the upper and lower sides were made into object conditions. In addition, calculation was performed in which heat is transmitted by radiation on the assumption that there are uniform walls at 160 ° C. above and below the cathode electrode.

  The results of the simulation are shown in FIGS. FIG. 10 is a graph showing the maximum temperature difference obtained from Examples 1 to 5 and Comparative Examples 1 and 2. Moreover, FIGS. 11-15 is a graph shown about transition of the temperature difference obtained from each of Examples 1-5, and FIG. 16 and FIG. 17 were obtained from each of the comparative examples 1 and 2, respectively. It is a graph shown about transition of a temperature difference.

(Maximum temperature)
First, referring to FIG. 10, in the range where the ratio t1 / t2 is 0.5 or more (Examples 1 to 5), the ratio t1 / t2 is smaller than 0.5 (Comparative Examples 1 and 2). The maximum temperature difference is effectively suppressed. When the difference between the maximum temperature difference and the temperature difference after saturation is suppressed, a change in the transient temperature difference is suppressed.

  Therefore, it became clear that when the ratio t1 / t2 is 0.5 or more as in Examples 1 to 5, warpage and distortion of the cathode electrode are suppressed.

(Peak of temperature difference)
In addition, referring to FIGS. 11 to 17, in Comparative Examples 1 and 2 (see FIGS. 16 and 17), a large peak having a peak occurs after about 10 minutes from the start of plasma generation. In Example 1 (see FIG. 11), a small peak is generated as compared with Comparative Examples 1 and 2. On the other hand, in Examples 2 to 5 (see FIGS. 12 to 15), such a mountain-shaped peak does not occur.

  Referring to Table 1, in Comparative Examples 1 and 2 and Example 1, the maximum temperature difference was recorded after about 10 minutes from the plasma generation, whereas in Examples 2 to 5, the maximum temperature difference was recorded. It can be seen that the maximum temperature difference is recorded in the time after Oita.

  Therefore, if the ratio t1 / t2 is 1 or more as in Examples 2 to 5, a rapid increase in temperature difference after the start of plasma generation is suppressed, and a change in transient temperature difference is more effectively suppressed. It became clear that

(Time until temperature difference stabilizes)
The time until the temperature difference is stabilized is about 200 to 250 minutes in Comparative Examples 1 and 2 (see FIGS. 16 and 17), and about 150 to 200 in Example 1 (see FIG. 11). Further, in Example 5 (see FIG. 15), the temperature difference gradually increases, and the time until the temperature difference is stabilized is about 200 to 250 minutes. On the other hand, in Examples 2-4 (refer FIGS. 12-14), it is about 10 minutes. Therefore, it has been clarified that the temperature difference can be stabilized earlier if the ratio t1 / t2 is 1 or more and 3 or less.

<When adjusting the material of each plate>
Next, in Example 6, a simulation was performed on the transition of the temperature difference between the shower plate and the backing plate after the start of plasma generation when the plasma CVD apparatus according to the above-described embodiment was used.

  In Example 6, the ratio of the heat capacity of the shower plate to the backing plate is set to 1 by using different materials as the material of the shower plate and the backing plate in a configuration in which the ratio of the thickness of the shower plate to the backing plate is less than ½. / 2 or more.

  On the other hand, in Comparative Example 3, a simulation was performed in the same manner as in Example 6 except that the same material was used as the material for the shower plate and the backing plate.

  Specifically, in each of Example 6 and Comparative Example 3, the thickness of the shower plate was 3 mm, the thickness of the column (fastening portion) was 10 mm, and the thickness of the backing plate was 17 mm. At this time, the ratio of the thickness of the shower plate to the backing plate is 0.18.

  Further, in Example 6, for each material of the shower plate and the backing plate, the material of the shower plate is the same thickness as the material of the backing plate and the heat capacity is 3.3 times (for example, in the above-described embodiment) The materials mentioned above were used. On the other hand, in Comparative Example 3, the same material (same material as the backing plate of Example 6) was used for both the shower plate and the backing plate.

  With the above configuration, the ratio of the heat capacity of the shower plate to the backing plate was 0.58 in Example 5 and 0.18 in Comparative Example 3.

  The results of this simulation are shown in FIGS. 18 is a graph showing the transition of the temperature difference obtained from Example 6, and FIG. 19 is a graph showing the transition of the temperature difference obtained from Comparative Example 3.

  In Example 6, as compared with Comparative Example 3, the peak of the temperature difference after the start of plasma generation is suppressed, and the temperature difference is stabilized early. Therefore, it has been clarified that even when the ratio of heat capacity is set by selecting a material, warping and distortion of the cathode electrode are suppressed.

  The present invention can be used as, for example, a plasma CVD apparatus for forming a thin film.

2 Shower plate (first plate)
3 Backing plate (second plate)
4 Buffer chamber 6 Intermediate fastening portion 7 Outer fastening portion 100, 200 Plasma CVD apparatus 101 Cathode electrode 102 Anode electrode 103 Processing vessel (processing chamber)
106 Plasma excitation power supply

Claims (6)

A plasma processing apparatus for forming a film on a substrate by converting a processing gas into plasma in a processing chamber,
In the processing chamber, the front and back surfaces are exposed to the gas phase and are arranged so as to face each other, and provided with an electrode pair that converts the processing gas into plasma between each other,
At least one electrode of the electrode pair includes a first plate disposed on the side facing the counterpart electrode forming a pair, and a second plate disposed on the opposite side of the electrode across the first plate. A plate and at least one fastening portion connecting the first and second plates to each other;
The plasma processing apparatus, wherein the ratio of the heat capacity of the first plate to the heat capacity of the second plate is 1/2 or more. The plasma processing apparatus according to claim 1, wherein a ratio of a heat capacity of the first plate to a heat capacity of the second plate is 1 or more.   The plasma processing apparatus according to claim 1 or 2, wherein a ratio of a heat capacity of the first plate to a heat capacity of the second plate is 3 or less. The first plate is a shower plate having a plurality of through holes for supplying the processing gas between the electrode pair,
The plasma processing apparatus according to any one of claims 1 to 3, wherein the second plate is a support plate that supports the shower plate. The plasma processing apparatus according to any one of claims 1 to 4, wherein the first plate and the second plate are made of the same material. 6. The plasma processing apparatus according to claim 1, wherein a plurality of sets of the electrode pairs are arranged side by side in the processing chamber.

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