JPH0559992B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a plasma chemical vapor deposition method and an apparatus thereof, and more particularly to a plasma chemical vapor deposition method and its apparatus for coating a workpiece with a complex shape such as a three-dimensional shape with a uniform film. It is related to the device. [Conventional technology and its problems] Conventionally, hard materials such as titanium nitride (TiN), titanium carbide (TiC), and vanadium carbide (VC) have been applied to the surface of metals to improve wear resistance, seizure resistance, etc. High-temperature treatment methods such as chemical vapor deposition and molten salt immersion are known as methods for coating substances. These methods have a problem in that the coating is carried out at around 1000° C., and therefore, although the adhesion of the coating layer is good, thermal distortion of the object to be treated tends to occur.
Furthermore, it has been impossible to apply this method to materials with low melting points such as aluminum alloys. Therefore, in recent years, coating at low temperatures (below 550° C.) has begun to be put into practical use by various physical vapor deposition methods including ion plating. However, in the ion plating method and the sputtering method, the gas pressure during processing is low, the mean free path of the gas particles is long, and the incidence of particles is unidirectional, so there is a problem that the throwing power of the coating layer is poor. However, in order to obtain a uniform coating, it is necessary to rotate the object to be treated, resulting in a high equipment cost. Therefore, in recent years, attempts have been made to lower the processing temperature of chemical vapor deposition using plasma. This plasma chemical vapor deposition method is a coating method that takes advantage of the fact that chemical reactions proceed extremely actively in plasma space, and this allows coating at low temperatures that are impossible with normal chemical vapor deposition methods. Currently, it is being put into practical use as a coating for silicon nitride (SiNx), silicon oxide (SiO ₂ ), etc. in some parts of the semiconductor manufacturing field. Recently, using this plasma chemical vapor deposition technique,
Hard coating technology is being actively developed to improve wear resistance, seizure resistance, etc. However, with this method, the possibility of coating a hard layer has only been confirmed, and it has only been put into practical use in some semiconductor fields, and it is difficult to uniformly coat treated materials such as three-dimensional shapes. It was hot. That is, in the semiconductor field, which has been partially put into practical use, the target material to be processed in plasma chemical vapor deposition is a flat object such as a wafer, and coating uniformity is considered only within a two-dimensional plane. It is something. Within this two-dimensional plane, it is relatively easy to uniformly distribute the excited gas and radicals involved in the reaction, and as a result, with this method, it is possible to uniformly coat a flat object, It is in practical use. On the other hand, in the field of hard layer coating, which targets tools, molds, etc., it is necessary to uniformly coat three-dimensional objects with complex shapes, so the technology used in the semiconductor field can be applied directly. This is because it is difficult to achieve uniform coating even when applied. This is thought to be because it is difficult to uniformly distribute the excited gas and radicals involved in the reaction within a three-dimensional space, resulting in non-uniform coating. As described above, it has been difficult to obtain a uniform coating by applying the plasma chemical vapor deposition method to a three-dimensional object. Recently, methods to solve this problem include a method of rotating the object to be processed (Japanese Patent Application Laid-Open No. 174569, 1982), and a method of installing a gas inlet and discharge coil around the object to be processed (Japanese Patent Application Laid-Open No. 60-1999). 63377) etc. have been proposed. However, in the former case, although it is possible to improve the uniformity of the coating in the horizontal direction, it is difficult to improve the uniformity of the coating in the height direction, and in the latter case, it is necessary to use a coil according to the object to be treated, which requires equipment. There are problems such as complexity, and no fundamental solutions have been found for any of them. Therefore, in order to solve the above-mentioned problems of the conventional technology, the present inventors conducted extensive studies focusing on the flow of gas, which is the basis of chemical vapor deposition, and as a result, they achieved the present invention. It is. [Object of the Invention] An object of the present invention is to provide a method and an apparatus for forming a uniform coating layer on an object having a three-dimensional complex shape by plasma chemical vapor deposition. [Description of the Invention] Structure of the Invention The plasma chemical vapor deposition method of the present invention includes a process of arranging a process target in a plasma reaction chamber, and a residual gas removal process of exhausting gas remaining in the reaction chamber. , a temperature raising step of introducing a temperature raising gas into the reaction chamber and heating the surface of the material to be treated to a predetermined deposition temperature, and introducing a deposition gas into the reaction chamber from a gas injection chamber, It is characterized by a vapor deposition process in which a film is uniformly grown on the surface of the object to be processed by maintaining the gas pressure difference with the gas injection chamber at 9 Torr or more and performing electric discharge (hereinafter referred to as this first method). invention). Next, the plasma chemical vapor deposition apparatus of the present invention includes a plasma reaction chamber which has an opposing electrode inside or at least a part of the inner wall surface serves as an opposing electrode, and has a gas inlet pipe and a gas outlet pipe, and a plasma reaction chamber provided inside the reaction chamber. a base that serves as a pair of poles with the opposing electrode and supports or places the material to be treated, and a temperature-raising gas that is provided in the plasma reaction chamber and has a gas injection port and is introduced from the gas introduction pipe. and a gas injection chamber for supplying deposition gas into the plasma reaction chamber, a differential pressure detection means for detecting a gas pressure difference between the gas injection chamber and the plasma reaction chamber, and a pressure difference detected by the differential pressure detection means. and a control means for controlling the gas pressure difference between the gas injection chamber and the plasma reaction chamber based on the comparison. This invention is characterized by comprising a differential pressure control means (hereinafter referred to as the second invention). More detailed description of the structure First, the plasma chemical vapor deposition method of the first invention will be described. First, a material to be processed is arranged in a plasma reaction chamber (material to be processed step). Materials to be treated include steel,
Metals such as aluminum, semiconductor substrates such as silicon, and members such as ceramics are used. Further, the placement location is not particularly limited as long as it is within the reaction chamber, and may be a jig such as a base or a hanger provided within the reaction chamber. Next, after sealing the reaction chamber, the gas remaining in the reaction chamber is removed (residual gas removal step). The residual gas is preferably removed using a vacuum pump such as a rotary pump or a diffusion pump, and the pressure is preferably reduced to 10 ^-3 Torr or less. If it exceeds 10 ^-3 Torr,
This is because it becomes difficult to form a coating layer with excellent adhesion. Furthermore, using a diffusion pump etc., 10 ^-4 Torr
The following is more preferable since it is possible to form a coating layer with better adhesion. Further, during this pressure reduction, it is preferable to heat the inside of the furnace using a heater or the like provided in the furnace. Next, a heating gas is introduced into the reduced pressure reaction chamber and electric discharge is performed to heat the surface of the object to be treated to a predetermined coating temperature (temperature raising step). The temperature-raising gas used in the temperature-raising step is preferably hydrogen gas, a rare gas such as helium, or a mixed gas thereof. The purpose of using these temperature-raising gases in the temperature-raising step is to promote heating while minimizing damage to the object to be processed due to ion bombardment during temperature-raising. Furthermore, the temperature-raising gas is ionized by the discharge, and the accelerated particles collide with the surface of the object to be processed, removing organic substances such as carbon and oil from the surface of the object, cleaning the surface of the object. can do. This discharge uses a direct current glow discharge, a high frequency alternating current glow discharge, or the like. Note that DC glow discharge is preferable because it can be constructed at low cost and has a large temperature raising ability. Further, the pressure inside the reaction chamber in this temperature raising step is preferably 10 ^-3 to 10 Torr. Especially when the discharge is due to a DC glow discharge, 10 ^-2 ~
If 10Torr is due to AC glow discharge, then 10 ^-3
~10 Torr is preferable, respectively. This is because if the pressure is lower than this range, the discharge becomes unstable, and if it is higher than this range, the temperature distribution of the object to be processed becomes non-uniform, both of which are undesirable. Next, a chemical vapor deposition gas is introduced into the reaction chamber, the gas pressure difference between the reaction chamber and the gas injection chamber is maintained at 9 Torr or more, and a discharge is performed to grow a film on the surface of the object to be processed (evaporation process ). The materials covered in this vapor deposition process include titanium (Ti), zirconium (Zr), hafnium (Hf),
Nitride, carbide of vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), boron (B), aluminum (Al) or silicon (Si), These include oxides, borides, mixtures thereof, and even diamond. In addition, the vapor deposition gases include Ti, Zr, Hf, V,
Compounds such as halides, hydrides, and organic compounds of Nb, Ta, Cr, Mo, W, B, Al, or Si, nitrogen, ammonia, hydrocarbons, or carbon oxide, and rare gases such as hydrogen and helium are used. . As means for controlling the gas pressure difference between the reaction chamber and the gas injection chamber in the vapor deposition process, it is preferable to mainly use a method of controlling the pressure inside the gas injection chamber. This is because the pressure inside the reaction chamber needs to be set within a pressure range suitable for vapor deposition, as will be explained later, while the pressure inside the gas injection chamber must be set to a positive pressure relative to the reaction chamber so that the gas flows into the reaction chamber. This is because it is only necessary that the value is set, and it can be set to an arbitrary value by using the control means. Examples of means for controlling the pressure in the gas injection chamber include changes in the area and number of gas injection ports, changes in gas composition, changes in gas flow rate, changes in displacement, and use of a compressor. First, the method of changing the area and number of gas injection ports is as follows.
This is a preferred method because only the differential pressure can be easily changed under the same gas composition, flow rate, displacement, etc. conditions. That is, by changing the area of each gas injection port and the number of gas injection ports and increasing the total cross-sectional area of the gas injection ports, the pressure in the ejection chamber is reduced, and therefore the differential pressure is reduced. on the other hand,
If the total cross-sectional area of the gas injection port is reduced, the pressure in the injection chamber will increase, and therefore the differential pressure will increase. Next, since the method of changing the gas composition does not require any device improvements, it can be used as a simple method. This method takes advantage of the fact that the escape ability differs depending on the type of gas, and reduces the differential pressure by increasing the proportion of gases with high escape ability, such as hydrogen gas, while argon, krypton, etc.
This is a method of increasing the differential pressure by increasing the proportion of a gas with a low escape ability, such as xenon. Next, the method of changing the gas flow rate and the method of changing the displacement amount are very preferable because the gas differential pressure can be easily controlled by adjusting the flow rate control valve provided in the gas inlet pipe, gas outlet pipe, etc. Both methods are preferably used simultaneously. This is because the pressure in the reaction chamber will change if only one of the methods is used. By decreasing the gas flow rate and correspondingly decreasing the displacement, the differential pressure can be reduced while keeping the pressure in the reaction chamber constant, while increasing the gas flow and correspondingly decreasing the displacement. By increasing the pressure in the reaction chamber, the pressure difference can be increased while keeping the pressure in the reaction chamber constant. Next, a method using a compressor is a method in which the gas in the gas injection chamber is pressurized to a desired pressure using a gas compression device and then injected from the gas injection port,
This is a preferred method because the differential pressure can be changed arbitrarily regardless of conditions such as the area and number of gas injection ports, gas composition, flow rate, and displacement. Either one of the above gas pressure differential control methods or a combination thereof is used as a gas differential pressure control means to maintain the gas pressure differential between the reaction chamber and the gas injection chamber at 9 Torr or more and to perform electric discharge to control the surface of the object to be treated. Grow a uniform film on the surface. Here, the differential pressure
The reason why the pressure difference is 9 Torr or more is that if the differential pressure is less than 9 Torr, the uniformity of the coating in the height direction will not be sufficient due to the difference in distance from the gas injection port, and the properties of the coating layer will not be sufficient. This is because it cannot be done. In addition, the pressure in the reaction chamber in the vapor deposition process is 10 ^-1
~20 Torr is preferred. This is because if the pressure in the reaction chamber is lower than this range, the growth rate of the film is slow, and if it is higher than this range, the discharge becomes unstable, such as the occurrence of arc discharge, which is undesirable. Further, for the discharge, a direct current or high frequency alternating current discharge or microwave discharge is used. Furthermore, the processing temperature in this vapor deposition process is 300°C.
It is preferable that the temperature is at least ℃. This is because if the treatment temperature is less than 300°C, undecomposed reaction gas will be taken into the film, making it impossible to obtain a film with sufficient film quality, and the adhesion to the object to be processed may deteriorate. This is because it decreases. Next, the plasma chemical vapor deposition apparatus of the second invention will be explained together with a specific example of the plasma chemical vapor deposition apparatus of the second invention shown in FIG. That is, the plasma chemical vapor deposition apparatus of the second invention comprises a plasma reaction chamber 1 which has an opposing electrode inside or at least a part of the inner wall surface serves as an opposing electrode, and which has a gas inlet pipe 8 and a gas outlet pipe 9; A base 5 is provided in the reaction chamber 1 and serves as a pair of opposite electrodes, and supports or places the material to be treated; differential pressure detection means for detecting a gas pressure difference between the gas injection chamber 2 and the plasma reaction chamber 1 for supplying temperature raising gas and vapor deposition gas introduced from the introduction pipe 8 into the plasma reaction chamber 1; Comparing means for comparing the gas differential pressure detected by the differential pressure detecting means with a reference value corresponding to 9 Torr; and controlling the gas differential pressure between the gas injection chamber and the plasma reaction chamber based on the comparison. and a differential pressure control means. The differential pressure detection means is a means for detecting the gas pressure difference between the gas injection chamber 2 and the plasma reaction chamber 1, and is preferably a pressure detection means for detecting the pressure inside the gas injection chamber or the gas introduction pipe 8. , plasma reaction chamber 1
It has a pressure detection means for detecting the internal pressure, and detects the differential pressure from the detected values obtained from both pressure detection means. The comparison means is a means for comparing the gas differential pressure detected by the above-mentioned differential pressure detection means with a reference value set in advance to a predetermined value. The standard value shall be 9 torr. By setting this reference value to 9 Torr, the gas pressure difference between the gas injection chamber and the plasma reaction chamber can be set to 9 Torr or more. The control means is means for controlling the gas pressure difference so that the gas pressure difference becomes equal to or higher than the reference value based on the comparison between the gas pressure difference and the reference value in the comparison means. This gas pressure differential is controlled by controlling at least one of the flow rate, pressure, and composition of the gas introduced into the plasma reaction chamber 1 and/or the flow rate of the gas discharged from the plasma reaction chamber 1. To give a specific example, the gas injection port 3 of the gas injection chamber 2
means for changing the area or number of gases, means for controlling the flow rate of gas by a flow control valve provided in the gas inlet pipe 8 or gas outlet pipe 7, means for controlling the flow rate of gas by a flow control valve provided in the gas inlet pipe 8 or gas outlet pipe 7, and means for controlling the flow rate of gas introduced from each gas pipe connected to different types of gas sources. Means for controlling a control valve that adjusts the composition and flow rate of gas by changing the type and amount, means for connecting a compressor to a gas introduction pipe and changing the pressure of gas by controlling the rotation speed and other parameters of the compressor, etc. There is a means of One of these concretely exemplified means
One or a combination of two or more. Here, the gas injection chamber preferably has a so-called shower-like shape in which the injection surface is planar and has an arbitrary number of injection ports on the injection surface. This is because the gas injected from the shower-shaped gas injection port generates a flow in the direction of injection, so it is easy to obtain the effect of changing the flow velocity due to the pressure difference, and it is easy to grow a uniform coating. In addition, in the case of gas injected from a ring-shaped gas injection port, the flow does not occur only in the injection direction, but the components of the flow are dispersed, and the effect of creating a pressure difference and changing the flow velocity is reduced. There is a risk that the film will become worn out, making it difficult to obtain a sufficient effect of growing a uniform film. Effects of the invention Regarding the effects of the first invention and the second invention,
Although it is not completely clear yet, it can be considered as follows. That is, in the first invention, a film is grown on the surface of the object to be processed by maintaining the gas pressure difference between the reaction chamber and the gas injection chamber at 9 Torr or higher and performing electric discharge in the vapor deposition process. Note that this change in gas pressure difference corresponds to a change in gas injection speed, and means that the larger the gas pressure difference, the faster the gas injection speed. The gas introduced into the reaction chamber is excited in a plasma atmosphere, and a chemical reaction occurs at a lower temperature than in normal chemical vapor deposition, forming a coating layer on the surface of the object to be processed. It is not always clear where and how the gas introduced into the reaction chamber is excited and participates in the reaction, but as it passes through the discharge space, the introduced gas gradually As the gas is decomposed into , the amount of gas changes in the flow direction, and the amount of excited gas and radicals generated also changes accordingly.Furthermore, the excited gas and radicals have a lifespan, so The distribution of gases involved in these reactions is
Location on the surface of the object to be treated, especially in the height direction (flow direction)
It is thought that this is changing due to When the gas differential pressure is small and the gas injection speed is slow, the reaction is slow because the gas transport speed is relatively slow compared to the speed of gas decomposition, excitation, etc., and the lifespan of the excited gas and radicals. The distribution of the gas involved changes depending on the height direction (flow direction),
It is thought that this results in non-uniform coating.
Furthermore, if the gas injection speed is slow, the effect of stirring the atmosphere due to the flow cannot be expected.
Gas stagnation tends to occur around the object to be treated, and this is also considered to be a cause of non-uniform coating. On the other hand, when the gas differential pressure is maintained at 9 Torr or more and the gas injection speed is increased as in the first invention, the gas transport speed becomes faster, so that the excited gas and radicals participate in the reaction. It is thought that a uniform coating can be obtained because the gas distribution becomes uniform in the height direction (flow direction) and gas stagnation is less likely to occur. Further, with the apparatus of the second invention, the above-mentioned gas differential pressure can be maintained at 9 Torr or more, so that a uniform coating layer can be obtained on the material to be treated. [Effects of the Invention] According to the method of the first invention, a uniform coating layer can be formed on a three-dimensional treated material. Moreover, the coating layer on the surface of the treated material obtained by the apparatus of the second invention is uniform. Furthermore, the apparatus of the second invention is a conventional plasma chemical vapor deposition apparatus provided with a gas differential pressure control means, and thus has a simple apparatus configuration. [Examples] Examples of the present invention will be described below. Example 1 A titanium nitride layer was formed on high-speed steel as a material to be treated by plasma chemical vapor deposition, and a performance evaluation test of the layer was conducted. Incidentally, the plasma chemical vapor deposition processing apparatus used in this processing is shown in FIG. First, a material to be treated 4 with an outer diameter of 20
Five vertically stacked pieces of high-speed steel (JIS SKH51) measuring mm x 10 mm thick were arranged at five positions approximately equally spaced apart from the center of the base 5 by 60 mm. Note that a cooling water pipe (not shown) for feeding cooling water is attached to the inside of the support column 6 of the base 5. Next, after the plasma reaction chamber 1 was sealed, the pressure was reduced to a residual gas pressure of 10 ⁻⁴ Torr using a rotary pump and a diffusion pump (not shown), which are vacuum pumps connected to the gas outlet pipe 7 . Note that the gas outlet pipes 7 are attached symmetrically to two locations at the bottom of the reaction chamber 1. Further, the gas introduction pipe 8 is connected to the reaction chamber 1.
It is connected to various gas cylinders (both not shown) via control valves. Next, hydrogen gas was flowed as a temperature raising gas into the reaction chamber 1, which was reduced in pressure to 10 ^-4 Torr, and the pressure inside the reaction chamber 1 was adjusted to be maintained at 1.0 Torr while being evacuated at the same time. Then, a DC voltage of several hundred volts is applied between the stainless steel anode plate 9 and the cathode (base) 5 provided inside the reaction chamber 1 to start discharging.
The temperature of the material to be treated was raised by ion bombardment until the surface reached 550°C. Here, the DC power supply circuit is composed of an anode 9 and a cathode 5, and the power is controlled by input from a two-color thermometer (not shown) that measures the temperature of the material to be treated inside. It works to keep it constant. Next, titanium tetrachloride (TiCl ₄ ) gas, nitrogen (N ₂ ) gas, hydrogen (H ₂ ) gas, and argon (Ar) gas were introduced as deposition gases, each with a flow rate of 4 c.c./min. 20c.c./min, 750c.c./min, 500
cc/min, and the vapor deposition process was carried out by sustaining DC discharge for 1.5 hours while maintaining the temperature of the material to be treated at 550°C. At that time, a shower-shaped gas injection chamber 2 with a diameter of 140 mm was adopted as a gas pressure differential control means.
The injection port 3 of the injection chamber 2 has 30 holes of φ0.7 mm (processing number 1) and 50 holes of φ0.5 mm.
(processing number 2) was used. At this time, the pressure inside the reaction chamber 1 was constant at 4 torr in both cases, but the pressure in the gas injection chamber was different because the number and area of the holes in the gas injection port 3 were different. The pressure difference was 20 Torr in the case of , and 22 Torr in the case of the latter (treatment number 2), so the differential pressures between reaction chamber 1 and gas injection chamber 2 were 16 Torr and 18 Torr, respectively. After the vapor deposition process, the discharge was stopped, the material to be treated was cooled under reduced pressure (~10 ^-3 Torr), and the material to be treated 4 was taken out from the reaction chamber 1, and a golden layer was found on the surface of the material to be treated. was formed. As a result of a material fixation test conducted on the golden layer on the surface of the treated material using an X-ray diffraction method, it was confirmed that all of the gold layers were titanium nitride (TiN). In addition, as a result of a measurement test of the layer thickness and surface hardness of this golden layer, the layer thickness was determined to be 10 mm from the base 5 and 50 mm for both treatment numbers 1 and 2.
The height in mm is approximately 2 μm, which is almost uniform in the height direction, and the hardness of the titanium nitride layer is
It was homogeneous with Hv2100Kg/mm ² (base metal height Hv800Kg/mm ² ). The results of layer thickness measurements are shown in FIG. In the figure, "A1" indicates the result of processing number 1, and "A2" indicates the result of processing number 2. For comparison, plasma chemical vapor deposition was performed on the same treated material (comparison sample) using the same equipment and method as described above, except that 300 holes of φ0.7 mm were provided in the injection port of the shower-shaped injection chamber described above. Processing (processing number C1)
I did this. At this time, the pressure inside the reaction chamber during the vapor deposition process was 4 Torr, and the pressure inside the gas injection chamber was
The gas pressure difference between the two was 3.2 Torr. As a result, a similar golden layer (TiN) was formed on the surface of the comparison sample, but the layer thickness was 0.4 μm at a height of 10 mm from the base and 3.4 μm at a height of 50 mm.
The coating layer was non-uniform in the height direction. The results of layer thickness measurements are also shown in FIG. 2. In the diagram, "C1"
shows the results of treatment number C1 of this comparative example. As is clear from the above, when the method and apparatus of this example are used, a more uniform coating layer can be obtained compared to the comparative example. Example 2 A device similar to the plasma chemical vapor deposition device used in Example 1 was used, and the displacement of the pump was varied.
TiN coating treatment was performed. In this example, in order to keep the pressure inside the furnace constant at 4 Torr, the exhaust volume was varied and the overall gas flow rate was varied.
The gas injection chamber used was a shower-shaped one with a diameter of 90 mm and 40 injection ports each having a diameter of 0.7 mm. First, Process I (process number 3) is a case where the displacement is the same as in Example 1, and TiCl ₄ 300c.c./min, _{N 2}
20c.c./min, H ₂ 750c.c./min and Ar500c.c./min
The TiN was coated by continuing DC discharge at 4 Torr for 1.5 hours while flowing. Next, the process (process number 4) is when the displacement is large,
TiCl ₄ 3c.c./min, N ₂ 20c.c./min, _{H 2} 1500c.c./
at 4Torr while flowing min and Ar750c.c./min.
Coating was carried out in the same manner for 1.5 hours. Furthermore, the treatment (comparative example: treatment number C2) is a case where the exhaust amount is small, TiCl ₄ 3c.c./min, _{N 2} 20c.c./min, _{H 2}
While flowing 500c.c./min and Ar200c.c./min
TiN coating was similarly performed at 4 Torr. In these cases, since the same gas injection chamber is used, the pressure in the gas injection chamber varies depending on the total flow rate of the gas, and in Process I as this example, the pressure is 14 Torr,
It was 30 Torr in the treatment, and 8 Torr in the treatment as a comparative example. Therefore, the gas differential pressures were 10 Torr, 26 Torr, and 4 Torr, respectively. After treatment, the layer thickness was measured and changes in height direction were investigated. The results are shown in FIG. In the figure, "A3" indicates Process I (process number 3), and "A4"
indicates a process (process number 4), and “C2” indicates a process as a comparative example (process number C2). In the processing of this embodiment according to the present invention,
A nearly uniform coverage was obtained. Further, in the treatment, a substantially uniform coating was obtained, although the overall coating thickness was slightly thinner. However, in the treatment as a comparative example, a uniform coating in the height direction could not be obtained. As described above, even when the same gas injection chamber was used and the pressure inside the reaction chamber was constant, the uniformity of the coating in the height direction varied greatly just by changing the displacement amount, that is, the total flow rate. Note that if the pump displacement is the same and the gas flow rate is changed, the pressure inside the reaction chamber will also change, but in this case as well, the height of the coating will be higher when the gas flow rate is larger and the differential pressure is larger. The directional uniformity was good. Example 3 A device similar to the plasma chemical vapor deposition device used in Example 1 was used, the displacement of the gas injection chamber and pump were the same, TiCl ₄ 4c.c./min, N ₂ 20c.c./min.
The coating treatment was carried out for 1.5 hours by changing the ratio of H ₂ flow rate and Ar flow rate under conditions of 4 Torr and 4 Torr of pressure in the reaction chamber. Processing of this example (processing number 5)
The coating was carried out under the conditions of H ₂ 750 c.c./min and Ar 500 c.c./min. In addition, the treatment as a comparative example (processing number C3) is H ₂ 1500c.c./min, Ar100
cc/min, processing (processing number C4) is H ₂ 1250
cc/min, Ar200c.c./min. In these cases, the same gas injection chamber is used, and the reaction chamber pressure and pump displacement are also the same, but the pressure in the gas injection chamber is different due to the difference in gas composition, and in the process of this example 13 Torr was 9.5 Torr in the comparative example process and 11.5 Torr in the process. Therefore,
The differential pressures were 9 Torr, 5.5 Torr and 7.5 Torr, respectively. After the treatment, the layer thickness was measured and the change in height direction was investigated. The results are shown in FIG. In the figure, "A5" indicates a process (process number 5), "C3" indicates a process as a comparative example (process number C3), and "C4" indicates a process as a comparative example (process number C4). In this way, as the Ar flow rate increases, the uniformity of the coating in the height direction becomes better, and in the treatment of this example according to the present invention where the gas differential pressure is 9 Torr, the coating is almost uniform with a thickness of about 2 μm. A good coating was obtained. As described above, even under the same conditions of gas injection chamber, pump displacement, and reaction chamber pressure, the uniformity of the coating in the height direction changed significantly just by changing the gas composition. As in Examples 1 to 3 above, the uniformity of the coating in the height direction varied greatly depending on the gas injection port, pump displacement, gas composition, etc. By changing these processing conditions, the differential pressure between the gas injection chamber and the reaction chamber changes. Examples 1-3
FIG. 5 shows the relationship between the differential pressure between the gas injection chamber and the reaction chamber and the uniformity of the coating in the height direction (layer thickness ratio) with respect to the results of and the results of their comparative examples. In the figure, "0" indicates the results of this example, and "●" indicates the results of the comparative example. When the differential pressure is small, a large difference in coating thickness is seen in the height direction, but as the differential pressure increases, the difference in coating thickness in the height direction becomes smaller, and when the differential pressure is about 9 Torr or more, It has been found that when the size is large, a nearly uniform coverage is obtained. As mentioned above, the uniformity of the coating in the height direction varied greatly depending on various processing conditions, but regardless of the processing conditions, uniform coating could be achieved by setting the differential pressure between the gas injection chamber and the reaction chamber to about 9 Torr or more. is obtained. still,
In Examples 1 to 3, the TiN coating using DC discharge was explained, but the same effect can be obtained regardless of the type of coating layer and discharge. Example 4 Using an apparatus similar to the plasma chemical vapor deposition apparatus used in Example 1, using the raw material gases and discharge means shown in the table, and at the gas differential pressure (differential pressure between the gas injection chamber and the reaction chamber) shown in the table. The same material to be treated as in Example 1 was subjected to plasma chemical vapor deposition treatment. Next, the layer thickness of the coating on the surface of the treated material was measured. 10 from its base
The ratio of the layer thickness with a height of mm to the layer height with a height of 50 mm is shown in the column of test results (treatment numbers 6 to 21). The closer this ratio is to 1, the more uniform the coating is formed. For comparison, comparison processing was carried out using the same method and apparatus as described above, except that the differential pressure was set to a value less than 9 Torr (processing numbers C5 to C12). Layer thickness measurements of the obtained coatings were carried out in the same manner. The obtained results are also shown in the table. Although it is necessary to appropriately select and use a means for adjusting the differential pressure depending on the type of raw material gas, etc., in any case of this embodiment according to the present invention, the differential pressure is 9 Torr or more and the coating is uniform in the height direction. was good.

【table】

[Table] Example 5 A TiC coating process was performed using a plasma chemical vapor deposition apparatus similar to that used in Example 1. At that time, a shower-like gas injection chamber similar to that in Example 1 was used as a gas differential pressure control means, and the material to be treated was
The same thing as above but twice the height (100mm). In addition, the deposition gas was TiCl ₄ 4 c.c./min,
CH ₄ 10c.c./min, _{H 2} 750c.c./min, Ar500c.c./min
The vapor deposition process was carried out under conditions of a reaction chamber pressure of 4 torr. In addition, the pressure inside the injection chamber at this time is
The gas pressure difference between the reaction chamber and the gas injection chamber was 15 Torr. As a result, a gray layer was formed on the surface of the treated material, and a substance identification test confirmed that this was titanium carbide (TiC). Next, the layer thickness of the coating layer on the surface of the treated material was measured. The results are shown in FIG. "A6" in the diagram is
These are the results of this example. In addition, (layer thickness at 10 mm height)/(layer thickness at 100 mm height) was 0.85. For comparison, the same material to be treated (comparison sample) was subjected to plasma chemical vapor deposition using the same equipment and method as described above, except that 150 holes of φ0.7 mm were made in the injection port of the shower-shaped gas injection chamber. I did this. At this time, the pressure inside the reaction chamber during the vapor deposition process was 4 Torr, the pressure inside the gas injection chamber was 11 Torr, and the gas pressure difference between the two was 7 Torr. The thickness of the obtained coating layer (TiC) was similarly measured.
The obtained results are also shown in FIG. In the figure,
"C5" is the result of a comparative example. In addition, (layer thickness at 10 mm height)/(layer thickness at 100 mm height) was 0.1. As is clear from FIG. 6, even when the height of the material to be treated is twice that of Example 1, when the method and apparatus of this example is used, the material is more uniform than that of the comparative example. It can be seen that a coating layer is obtained.

[Brief explanation of the drawing]

The figures show examples of the present invention; FIG. 1 is a schematic diagram of a specific example of the present invention and a plasma chemical vapor deposition apparatus used in Examples 1 to 5; and FIG. Figure 3 is a diagram showing the relationship between the height from the base and layer thickness obtained in Example 2, and Figure 4 is a diagram showing the relationship between the height from the base and layer thickness obtained in Example 2. Figure 5 is a diagram showing the relationship between the height from the base and the layer thickness obtained in Example 3, and Figure 5 summarizes the results obtained in Examples 1 to 3. FIG. 6 is a diagram showing the relationship between the height from the base and the layer thickness obtained in Example 5. 1... Plasma reaction chamber, 2... Gas injection chamber, 3
... Gas injection port, 4 ... Material to be treated, 5 ... Base,
6... Support column, 7... Gas outlet pipe, 8... Gas introduction pipe.

Claims (1)

[Scope of Claims] 1. A process for arranging a material to be processed in a plasma reaction chamber; a residual gas removal process for exhausting gas remaining in the reaction chamber; and a step for discharging a gas remaining in the reaction chamber. introducing a vapor deposition gas from the gas injection chamber into the reaction chamber, and increasing the gas pressure difference between the reaction chamber and the gas injection chamber to 9. A plasma chemical vapor deposition method comprising the steps of: a vapor deposition process in which a film is uniformly grown on the surface of a material to be treated by maintaining the temperature above Torr and performing electric discharge. 2. A plasma reaction chamber that has an opposing electrode inside or at least a part of the inner wall surface serves as an opposing electrode, and has a gas inlet pipe and a gas outlet pipe; a base for supporting or placing a material to be processed; and a base provided in the plasma reaction chamber, having a gas injection port, and supplying a heating gas and a vapor deposition gas introduced from the gas introduction pipe into the plasma reaction chamber. a gas injection chamber for detecting a gas injection chamber; a pressure difference detection means for detecting a gas pressure difference between the gas injection chamber and the plasma reaction chamber; and a reference value corresponding to the gas pressure difference detected by the pressure difference detection means and 9 torr. and a gas differential pressure control means comprising a comparison means for comparing the values, and a control means for controlling the gas pressure difference between the gas injection chamber and the plasma reaction chamber based on the comparison. Plasma chemical vapor deposition equipment.