The embodiments of the present invention relate to a film forming apparatus and plate.
A film forming apparatus used in an epitaxial growth method for a SiC film or the like needs to heat a substrate at high temperatures between 1500° C. and 1700° C. Therefore, for example, a gas supplier provided in an upper portion of a film formation chamber is also expected to be exposed to high temperatures due to radiation from a heater for heating the substrate, and the like. When a source gas and a doping gas circulate by convection near the gas supplier and are heated, deposits including a material and a dopant adversely adhere to the surface of the gas supplier. These deposits having adhered to the gas supplier become particles to fall on the substrate and lead to device malfunction. There is also a problem that the doping concentration of the SiC film changes with time due to exhaust of a dopant gas from the deposits having adhered to the gas supplier (a memory effect).
A film forming apparatus according to the present embodiment comprises: a film formation chamber capable of accommodating a substrate; a gas supplier including a plurality of nozzles provided in an upper portion of the film formation chamber to supply a process gas onto a film formation face of the substrate, and a cooling part configured to suppress a temperature increase of the process gas; a heater configured to heat the substrate to 1500° C. or higher; and a plate opposed to a bottom face of the gas supplier, where first opening parts of the nozzles are formed, in the film formation chamber, and arranged away from the bottom face, in which the plate includes a plurality of second opening parts having a smaller diameter than the first opening parts, and arranged substantially uniformly in a plane of the plate, and a partition protruded on an opposed face to the gas supplier and separating the plane of the plate into a plurality of regions.
A plate according to the present embodiment is a plate opposed to a gas supplier configured to supply a gas onto a film formation face of a substrate in a film formation chamber, the plate being placed away from the gas supplier, the plate including: a plurality of second opening parts having a smaller diameter than first opening parts of nozzles provided on the gas supplier to supply the gas, the second opening parts being arranged substantially uniformly in a plane of the plate; and a partition protruded on an opposed face to the gas supplier.
Embodiments of the present invention will now be explained with reference to the drawings. The present invention is not limited to the embodiments. The drawings are schematic or conceptual and the ratios and the like among the respective constituent elements are not necessarily the same as those of actual products. In the present specification and the drawings, elements identical to those described in the foregoing drawings are denoted by like reference signs and detailed explanations thereof are omitted as appropriate.
A film forming apparatus according to the present embodiment comprises: a film formation chamber capable of accommodating a substrate; a gas supplier including a plurality of nozzles provided in an upper portion of the film formation chamber to supply a process gas onto a film formation face of the substrate, and a cooling part configured to suppress a temperature increase of the process gas; a heater configured to heat the substrate to 1500° C. or higher; and a plate opposed to a bottom face of the gas supplier, where first opening parts of the nozzles are formed, in the film formation chamber, and arranged away from the bottom face, in which the plate includes a plurality of second opening parts having a smaller diameter than the first opening parts, and arranged substantially uniformly in a plane of the plate, and a partition protruded on an opposed face to the gas supplier and separating the plane of the plate into a plurality of regions.
A plate according to the present embodiment is a plate opposed to a gas supplier configured to supply a gas onto a film formation face of a substrate in a film formation chamber, the plate being placed away from the gas supplier, the plate including: a plurality of second opening parts having a smaller diameter than first opening parts of nozzles provided on the gas supplier to supply the gas, the second opening parts being arranged substantially uniformly in a plane of the plate; and a partition protruded on an opposed face to the gas supplier.
The chamber 10 being a film formation chamber is capable of accommodating a substrate W and is, for example, made of stainless steel. The inner portion of the chamber 10 is depressurized by a vacuum pump (not illustrated). The chamber 10 includes a head part 12 and a body part 13. The gas supplier 40 and the cooling part 31 are provided in the head part 12. The temperature of a process gas including a source gas, a carrier gas, an assist gas, and a doping gas supplied from the gas supplier 40 is suppressed from increasing by the cooling part 31 in the inner portion of the head part 12 of the chamber 10. Therefore, the inner portion of the head part 12 of the chamber 10 is hereinafter referred to as “temperature increase suppression region Rc”. The assist gas is a gas functioning to prevent overreaction of the source gas, and the like. For example, when Si-based gas is used as the source gas in formation of a SiC film, an effect of preventing clustering of Si in a gas phase and the like is obtained by addition of HCl as the assist gas.
The susceptor 60, the rotation mechanism 80, the lower heater 90, the upper heater 95, and the like are provided in the chamber 10 at the body part 13. The gas supplied from the gas supplier 40 is heated inside the body part 13 and reacts on the surface of the substrate W. Accordingly, a film is epitaxially grown on the substrate W. The film is, for example, a SiC film.
The internal diameter of the liner 110 included in the head part 12 of the chamber 10 is equal to or smaller than that of the liner 20 included in the body part 13. The liner 110 is a hollow cylindrical member that covers the inner wall of the head part 12 of the chamber 10 to suppress generation of deposits on the inner wall of the head part 12. A material being high in the infrared transmissivity, for example, quartz is used as a material of the liner 110. This configuration suppresses the liner 110 from being heated to high temperatures by radiation from the upper heater 95 and the lower heater 90 through the liner 20, the susceptor 60, and the substrate W. The liner 110 is placed so as not to scrape against the inner wall of the head part 12 even when thermally deformed. Accordingly, the outer wall surface of the liner 110 and the inner wall surface of the head part 12 are arranged away from each other, except a support (not illustrated in
The liner 20 is a hollow cylindrical member that covers the inner wall of the chamber 10 to suppress generation of deposits on the upper heater 95, the heat insulator 96, and the inner wall of the body part 13. The liner 20 is heated to high temperatures by radiation from the upper heater 95 and functions as a hot wall for heating the substrate W by radiation. A material having a high heat resistance is selected as a material of the liner 20 and, for example, carbon or carbon coated with SiC is used.
The cooling part 31 is provided in the head part 12 of the chamber 10 and is, for example, a flow path of a refrigerant (for example, water). With flowing of the refrigerant in the flow path, the cooling part 31 suppresses a temperature increase of the gas in the temperature increase suppression region Rc. As illustrated in
The cooling part 35 is provided in the body part 13 of the chamber 10 and is, for example, a flow path of a refrigerant (for example, water) similarly to the cooling part 31. However, the cooling part 35 is not provided to cool a space in the body part 13 but is provided to prevent heat from the upper heater 95 and the lower heater 90 from heating the body part 13 of the chamber 10.
The gas supplier 40 is provided on the top face of the chamber 10, opposed to the surface of the substrate W and includes a plurality of nozzles N. The gas supplier 40 is provided above the lower heater 90 and the upper heater 95 and is located in an upper portion of the temperature increase suppression region Rc. The gas supplier 40 supplies the source gas (Si-based gas, C-based gas, or the like), the doping gas (nitrogen gas, aluminum-containing gas, or the like), the assist gas (HCl gas, or the like), and the carrier gas (hydrogen gas, argon gas, or the like) to the temperature increase suppression region Rc in the chamber 10 through the nozzles N.
The exhaust part 50 is provided on the bottom of the chamber 10 and exhausts the gas having been used in the film formation process to the outside of the chamber 10.
The susceptor 60 is an annular member on which the substrate W can be mounted and is, for example, made of carbon. The support 70 is a cylindrical member capable of supporting the susceptor 60 and is, for example, made of carbon similarly to the susceptor 60. The support 70 is connected to the rotation mechanism 80 and is configured to be rotatable by the rotation mechanism 80. The support 70 can rotate the substrate W with the susceptor 60. The susceptor 60 and the support 70 may be formed of a material having a resistance to high temperatures equal to or higher than 1500° C., such as SiC (silicon carbide), TaC (tantalum carbide), W (tungsten), or Mo (molybdenum) as well as carbon. Carbon coated with SiC or TaC may be used for the susceptor 60 and the support 70.
The lower heater 90 is placed below the susceptor 60 and the substrate W and inside the support 70. The lower heater 90 heats the substrate W from below through the susceptor 60. The upper heater 95 is placed along a side surface of the heat insulator 96 provided on an inner circumference of the body part 13 of the chamber 10 and heats the substrate W from above through the liner 20. The lower heater 90 and the upper heater 95 heat the substrate W to high temperatures equal to or higher than 1500° C. while the rotation mechanism 80 rotates the substrate W, for example, at a rotational speed equal to or higher than 300 rpm. This operation enables the substrate W to be uniformly heated.
The reflector 100 is placed between the head part 12 and the body part 13 in the chamber 10 and is, for example, made of carbon. The reflector 100 reflects the heat from the lower heater 90 and the upper heater 95 downward. Accordingly, the temperature of the head part 12 is prevented from excessively increasing by the radiation from the lower heater 90 and the upper heater 95. The reflector 100 and the cooling part 31 function to cause the temperature in the temperature increase suppression region Rc to be lower than a reaction temperature of the source gas. The reflector 100 may be formed of a material having a resistance to high temperatures equal to or higher than 1500° C., such as SiC (silicon carbide), TaC (tantalum carbide), W (tungsten), or Mo (molybdenum) as well as carbon. Although the reflector 100 may be one thin plate, a configuration in which a plurality of thin plates are spaced at appropriate intervals is preferable to efficiently reflect the heat.
Configurations of the liner 110 and the plate 120 are explained with reference to
The liner 110 is a hollow cylindrical member that covers the inner wall of the head part 12 in the chamber 10 to suppress generation of deposits on the inner wall of the head part 12. The liner 110 is supported by the support 140 provided on the side of the inner wall of the head part 12. A material being high in the infrared transmissivity, for example, quartz is used as a material of the liner 110. This configuration suppresses the liner 110 from being heated to high temperatures by the radiation from the upper heater 95 and the lower heater 90 through the liner 20, the susceptor 60, the substrate W, or the like. The liner 110 is placed not to be in contact with the inner wall of the head part 12 even when thermally deformed. Accordingly, the outer wall surface of the liner 110 is located away from the inner wall surface of the head part 12, except the support 140.
The plate 120 is provided below the gas supplier 40 and is arranged along the inner edge of the liner 110. The plate 120 has a substantially circular planar shape and is constituted of a material being high in the infrared transmissivity such as quartz. This configuration suppresses the plate 120 from being heated to high temperatures. The plate 120 is partially mounted on the liner 110 by a support 121d of the plate 120. A gap GP2 is provided between the plate 120 and the liner 110, except a contact part between the support 121d and the liner 110. The gap GP2 enables a purge gas from an opening part OP10 described later to flow along an inner circumferential side surface of the liner 110. This operation enables the source gas introduced from second opening parts OP2 described later into the temperature increase suppression region Rc to be prevented from easily reaching the liner 110 and suppresses generation of reaction by-products on the surface of the liner 110.
The plate 120 is placed at a location facing the first opening parts OP1 of the nozzles N of the gas supplier 40 in the chamber 10 and is arranged away from the bottom face of the gas supplier 40. The plate 120 is provided to cover the bottom face of the gas supplier 40, where the first opening parts OP1 are located. Meanwhile, there is a gap GP between the gas supplier 40 and the plate 120, and the plate 120 is not in direct contact with the gas supplier 40. This configuration prevents interference of the plate 120 with the bottom face of the gas supplier 40 even when the plate 120 is thermally deformed due to a temperature increase.
The plate 120 has the second opening parts OP2 arranged substantially uniformly in a plate plane. The second opening parts OP2 each have a smaller diameter than the first opening parts OP1. Therefore, the gas from the first opening parts OP1 temporarily remains in the gap GP and is thereafter substantially uniformly introduced into the temperature increase suppression region Rc through the second opening parts OP2. In this way, the plate 120 has a gas rectifying effect due to the second opening parts OP2.
The plate 120 includes partitions 121a, 121b, and 121c protruded on an opposed face F120 that is opposed to the gas supplier 40. As described later, the partitions 121a, 121b, and 121c are provided concentrically in a substantially circular manner in the opposed face F120 of the plate 120.
The opening part OP10 provided on the gas supplier 40 is a hole formed to supply the purge gas. As described above, the purge gas supplied from the opening part OP10 flows along the inner circumferential side surface of the liner 110 through the gap GP2 between the plate 120 and the liner 110. This operation enables the source gas introduced from the second opening parts OP2 into the temperature increase suppression region Rc to be less likely to reach the liner 110 and suppresses generation of reaction by-products on the surface of the liner 110.
The plate 120 has the partitions 121a, 121b, and 121c on the opposed face F120. A central region enclosed by the first partition 121a, which is located on the innermost circumference side among the partitions 121a, 121b, and 121c, is a first plate region R1. An intermediate region between the second partition 121b located on the outer circumference side of the first partition 121a and the first partition 121a is a second plate region R2. An outer region between the third partition 121c located on the outer circumference side of the second partition 121b and the second partition 121b is a third plate region R3.
The second opening parts OP2 are arranged substantially uniformly in the plate plane and substantially uniformly introduce the gas supplied to each of the regions R1 to R3 into the chamber 10. The first opening parts OP1 facing the first plate region R1 are denoted by OP1_1, the first opening parts OP1 facing the second plate region R2 are denoted by OP1_2, and the first opening parts OP1 facing the third plate region R3 are denoted by OP1_3. The opening parts OP1_1 to OP1_3 supply the gas to the regions R1 to R3 separated by the partitions 121a to 121c, respectively. The nozzles N of the openings parts OP1_1 to OP1_3 supply gases of concentrations different from each other or gases of types (compositions) different from each other, respectively, to the gap GP between the gas supplier 40 and the plate 120. Therefore, with the partitions 121a to 121c, the gasses supplied to the regions R1 to R3 are introduced into the chamber 10 through the second opening parts OP2 while being little mixed with each other in the gap GP.
The gas supplier 40 supplies the source gas (for example, silane gas, propane gas, or the like), the doping gas (for example, nitrogen gas, TMA (Trimethylaluminium) gas, diborane, or the like), the assist gas (HCl gas, or the like), the carrier gas (for example, hydrogen gas, argon gas, or the like) from the nozzles N.
The gas supplier 40 can change the ratio among the source gas, the doping gas, the assist gas, and the carrier gas, or the concentrations thereof in the regions R1 to R3. For example, the gas supplier 40 can change the ratio (C/Si ratio) between the silicon amount of silane in the source gas and the carbon amount in the propane gas in the regions R1 to R3. The gas supplier 40 also can change the flow rate of hydrogen gas as the carrier gas in the regions R1 to R3. Accordingly, the film thickness of the SiC film or the doping concentration in the plane of the substrate W can be adjusted to be substantially uniform.
In this way, the gas supplier 40 can supply the gases different in the concentration ratio to the regions R1 to R3, respectively. Since the plate 120 has the partitions 121a to 121c, the gasses supplied to the gaps GP in the regions R1 to R3 are prevented from being mixed and are substantially uniformly introduced into the chamber 10 from the second opening parts OP2, respectively.
While having the second opening parts OP2 to be opposed to the first opening parts OP1_1 to OP1_3 of the gas supplier 40, the plate 120 according to the present embodiment have no opening parts larger than the second opening parts OP2. Therefore, the gasses supplied from the first opening parts OP1_1 to OP1_3 temporarily remain in the associated gaps GP of the regions R1 to R3 and are then introduced into the chamber 10 through the second opening parts OP2 without being directly introduced into the chamber 10. Therefore, the plate 120 can substantially uniformly introduce the gas from each of the regions R1 to R3 into the chamber 10.
The gas supplier 40 has third opening parts OP3 as illustrated in
For example, it is desirable that the first distance d1 is about between 1.0 mm (millimeter) and 8.0 mm and the second distance d2 is about between 0.5 mm and 2 mm. If the first distance d1 is smaller than 1.0 mm, the gas separation effect with the partitions 121a to 121c is less likely to be obtained. If the first distance d1 is larger than 8.0 mm, the radiation effect from the plate 120 to the gas supplier 40 is reduced. If the second distance d2 is smaller than 0.5 mm, there is a risk that a part of the partitions 121a to 121c interferes with the gas supplier 40 due to deformation of the plate 120 because of a temperature increase. On the other hand, if the second distance d2 is larger than 2.0 mm, the partitions 121a to 121c cannot separate the gases in the regions R1 to R3 from each other. It is desirable that the ratio (d2/d1) between d1 and d2 is equal to or lower than 0.5. If d2/d1 is larger than 0.5, the gas separation effect is less likely to be obtained.
The diameter of the second opening parts OP2 on the plate 120 is, for example, not smaller than 0.5 mm and not larger than 5 mm. The total area of the second opening parts OP2 provided on the plate 120 is not less than 5% and not more than 25% with respect to the area of the face F120 of the plate 120 or the opposite face. If the diameter of each of the second opening parts OP2 is smaller than 0.5 mm, the gas flow from the plate 120 into the chamber 10 is deteriorated and the gas is likely to remain in the gap GP. Accordingly, the gas separation effect in the regions R1 to R3 separated by the partitions 121a to 121c is less likely to be obtained. If the diameter of each of the second opening parts OP2 is larger than 5 mm, the plate 120 ununiformly passes the gas depending on the positions of the first opening parts OP1 and therefore the gas rectifying effect is less likely to be obtained. If the total area of the second opening parts OP2 is less than 5% with respect to the area of the face F120 of the plate 120 or the opposite face, the gas flow deteriorates and therefore the gas is likely to remain in the gap GP. Accordingly, the gas separating effect in the regions R1 to R3 is less likely to be obtained. On the other hand, if the total area of the second opening parts OP2 is larger than 25% with respect to the area of the face F120 of the plate 120 or the opposite face, the plate 120 ununiformly passes the gas depending on the positions of the first opening parts OP1 and therefore the rectifying effect with the plate 120 is less likely to be obtained. Furthermore, the second opening parts OP2 are more likely to deform due to heat.
With the configuration described above, the film forming apparatus 1 according to the present embodiment can change the gas concentrations or the flow rates in the regions R1 to R3 while preventing mixture of the gas in the gap GP using the partitions 121a to 121c. As a result, uniformity in the film quality (the film thickness, the doping concentration, the mixed crystal composition ratio, the crystallinity, and the like) of a film formed on the substrate W can be enhanced.
In
In contrast thereto, in
As described above, the film forming apparatus 1 according to the present embodiment can control the distribution profile of the doping concentration in a film formed on the substrate W by adjusting the C/Si ratio of the gas from the center of the gas supplier 40 toward the outer circumference direction. That is, the in-plane uniformity of the doping concentration in a film formed on the substrate W can be improved.
In
In contrast thereto, in
As described above, the film forming apparatus 1 according to the present embodiment can control the distribution profile of the film thickness of a film formed on the substrate W by adjusting the flow rate of hydrogen gas. That is, the in-plane uniformity of the film thickness of a film formed on the substrate W can be improved.
The plate 120 has a partition 121e all around each of the fourth opening parts OP4. Each of the partitions 121e is continuous with any of the partitions 121a to 121c and individually surrounds each of the fourth opening parts OP4. Therefore, the hydrogen gas from the third opening parts OP3 can be prevented from entering the gap GP between the plate 120 and the gas supplier 40. Accordingly, the film forming apparatus 1 can easily control the flow rate of the hydrogen gas in each of the regions R1 to R3.
Each of the jigs 150a is formed by bending a rectangular column member and has a protrusion 151a as illustrated in
Each of the jigs 150b is formed of a rectangular column member and has a protrusion 151b as illustrated in
The jigs 150a and 150b are fixed on the surface of the plate 120 by fitting the protrusions 151a and 151b of the jigs 150a and 150b into the opening parts OP2, respectively, whereby the partition 121a can be constituted.
As in the above explanations of the partitions 121a and 121b, each of the jigs 150a and 150b may be integrally formed. Alternatively, each of the jigs 150a may be divided into a lower portion of the protrusion 151a and an upper portion located thereabove. Each of the jigs 150b may be divided into a lower portion of the protrusion 151b and an upper portion located thereabove. In this case, each of the jigs 150a and 150b is constituted by connecting the lower portion and the upper portion to each other.
The configuration of the partition 121a has been explained above. The shape of the partition 121a in the planar layout seen from the direction of gas supply to the plate 120 can be changed by combining the jigs 150a and 150b or other jigs different in the shape or size from the jigs 150a and 150b. The shape of the partition 121b in the planar layout seen from the direction of gas supply to the plate 120 also can be freely constituted by combining the jigs 150a and 150b or other jigs different in the shape or size from the jigs 150a and 150b.
The rest of the configuration of the third embodiment may be identical to the corresponding one of the first embodiment. Therefore, as illustrated in
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2020-082627 | May 2020 | JP | national |
This application is based upon and claims the benefit of priority from the prior International Patent Application No. PCT/JP/2021/013327 and the prior Japanese Patent Application No. 2020-082627, filed on May 8, 2020, the entire contents of which are incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/JP2021/013327 | Mar 2021 | US |
Child | 17971701 | US |