JP5496721B2 - Film forming apparatus and film forming method - Google Patents

Description

  The present invention relates to a film forming apparatus and a film forming method.

  Conventionally, an epitaxial growth technique has been used for manufacturing a semiconductor element that requires a relatively thick crystal film, such as a power device such as an IGBT (Insulated Gate Bipolar Transistor).

  In the vapor phase growth method used in the epitaxial growth technique, for example, when a silicon (Si) crystal is grown on a semiconductor substrate to obtain a Si single crystal substrate, a semiconductor substrate such as a silicon wafer is disposed. The film growth chamber for phase growth is maintained at normal pressure (0.1 MPa (760 Torr)) or reduced pressure.

Then, while heating the semiconductor substrate, a dopant gas such as boron-based diborane (B ₂ H ₆ ), phosphorus-based phosphine (PH ₃ ), or arsenic-based arsine (AsH ₃ ) is used as a source gas serving as a silicon source. The mixed process gas is supplied into the deposition chamber for vapor phase growth. Then, a thermal decomposition reaction or hydrogen reduction reaction of the source gas occurs on the surface of the semiconductor substrate heated to a predetermined temperature or more, and a gas phase doped with boron (B), phosphorus (P), or arsenic (As). A growth film is formed.

  In order to manufacture a thick epitaxial wafer with a high yield, it is necessary to improve the deposition rate by bringing new process gases into contact with the surface of the uniformly heated wafer one after another. Therefore, in a conventional film forming apparatus, for example, epitaxial growth is performed while rotating a wafer at a high speed.

  Further, as another method of manufacturing a thick epitaxial wafer with a high yield, improvement of the apparatus from the process gas supply surface is attempted. That is, when the process gas is supplied into the film forming chamber of the film forming apparatus, the device on the film forming apparatus is devised so that the process gas is efficiently collected on the surface of the semiconductor substrate.

  For example, in Patent Document 1, a process gas supplied into a film formation chamber is rectified, and a rectifying plate that supplies the process gas toward a semiconductor substrate held by a holder, and an inner diameter at the upper end of the rectifying plate are installed at the lower part of the rectifying plate. There has been disclosed a semiconductor manufacturing apparatus including an annular rectifying fin having a larger inner diameter at the lower end and rectifying gas discharged from the semiconductor substrate in the outer circumferential direction downward. By providing such a structure, the utilization efficiency of the process gas is improved.

JP 2009-231587 A

  FIG. 4 is a schematic cross-sectional view for explaining the configuration of a film forming apparatus using an epitaxial growth technique. A film forming apparatus 200 shown in FIG. 4 is configured to enable high-speed rotation of the semiconductor substrate as described above and efficient use of process gas.

  In the film forming apparatus 200 shown in FIG. 4, 201 is a chamber as a film forming chamber, 202 is a hollow cylindrical liner that covers and protects the inner wall of the chamber, 203a and 203b are flow paths of cooling water that cool the chamber, 204 Is a supply unit for introducing the process gas 225, 205 is an exhaust unit for the process gas after the reaction, 206 is a semiconductor substrate such as a wafer for vapor phase growth, 207 is a susceptor for supporting the semiconductor substrate 206, 208 is a support unit (not shown) 209 is a flange portion for connecting the upper and lower portions of the chamber 201, 210 is a packing for sealing the flange portion 209, 211 is a flange portion for connecting the exhaust portion 205 and the pipe, and 212 is A packing for sealing the flange portion 211.

  The liner 202 is usually made of quartz and has transparency. A shower plate 220 which is a gas rectifying plate for uniformly supplying the process gas 225 to the surface of the semiconductor substrate 206 is attached to the upper opening of the head 231 of the liner 202.

  A rotation shaft 222 extending to the inside of the chamber 201 is provided at the bottom of the chamber 201. A rotating cylinder 223 is disposed at the upper end of the rotating shaft 222, and the above-described susceptor 207 is attached to the rotating cylinder 223. Thereby, the susceptor 207 is rotatably arranged inside the chamber 201 above the heater 208.

  In the film forming apparatus 200, the semiconductor substrate 206 is supported by the susceptor 207 in the chamber 201. Then, the semiconductor substrate 206 is heated to 1000 ° C. or more by the heater 208 while rotating the semiconductor substrate 206 while being placed on the susceptor 207 by the rotating shaft 222 provided with a rotating mechanism (not shown). In this state, a process gas 225 containing a reactive gas is supplied into the chamber 201 from the supply unit 204 through the through hole 221 of the shower plate 220.

  Then, a thermal decomposition reaction or a hydrogen reduction reaction occurs on the surface of the semiconductor substrate 206, and a crystal film is formed on the surface of the semiconductor substrate 206. At this time, the process gas other than that used for the vapor phase growth reaction becomes a modified product gas, and is sequentially exhausted from the exhaust unit 205 provided at the lower portion of the chamber 201 together with the process gas 225.

  As described above, in the film forming apparatus 200, the semiconductor substrate 206 is epitaxially grown while rotating at high speed. As a result, a new process gas is brought into contact with the surface of the uniformly heated semiconductor substrate one after another so as to improve the deposition rate.

  Further, in the film forming apparatus 200 shown in FIG. 4, the through hole 221 of the shower plate 220 is arranged in a region corresponding to the semiconductor substrate 206. Thereby, the process gas 225 supplied from the supply unit 204 can be uniformly supplied onto the semiconductor substrate 206 on the susceptor 207.

  The liner 202 having a hollow cylindrical shape is configured such that the inner diameter of the head portion 231 that supports the shower plate 220 is smaller than the body portion 230 where the susceptor 207 is disposed. That is, the liner 202 having a hollow cylindrical shape supports the shower plate 220 on the upper side of the body 230 where the semiconductor substrate 206 is disposed, and the flow path of the process gas 225 that has passed through the shower plate 220. The inner diameter of the head portion 231 becomes smaller. That is, the liner 202 has a so-called structure in which the cross-sectional area of the head portion 231 is narrowed with respect to the trunk portion 230.

  By doing so, it is possible to reduce a useless space in which the process gas 225 exiting the through hole 221 of the shower plate 220 is diffused. Thereby, the process gas 225 supplied from the shower plate 220 is collected on the surface of the semiconductor substrate 206 without waste, and the process gas 225 can be efficiently used.

  The process gas 225 supplied from the supply unit 204 into the chamber 201 passes through the head 231 and efficiently flows down toward the surface of the semiconductor substrate 206. At this time, the gap between the peripheral portion of the semiconductor substrate 206 and the liner 202 is narrowed so that the flow of the process gas 225 on the surface of the semiconductor substrate 206 becomes more uniform. Specifically, the gap between the corner portion 234 of the stepped portion 232 and the peripheral portion of the semiconductor substrate 206 at the boundary between the head portion 231 and the trunk portion 230 of the liner 202 is narrowed.

  However, it has been found that one problem occurs here. That is, the radiant heat from the heater 208 is transmitted not only to the semiconductor substrate 206 but also to all members constituting the film forming apparatus 200 and raises the temperature thereof. Such a temperature rise is remarkable in the vicinity of high-temperature portions such as the semiconductor substrate 206 and the heater 208.

  For this reason, a relatively high temperature portion is generated at the boundary between the body portion 230 and the head portion 231 of the liner 202, which is close to the semiconductor substrate 206 and the heater 208. In particular, the temperature is very high at the corner 234 of the step 232 of the liner 202 near the semiconductor substrate 206 and the susceptor 207. On the other hand, the process gas 225 supplied into the chamber 201 passes through the head 231 and efficiently flows down toward the surface of the semiconductor substrate 206, undergoes a film formation reaction on the surface of the semiconductor substrate 206, and part of it The flow direction is changed in the vicinity of the corner portion 234 of the step portion 232, and after flowing toward the peripheral direction of the semiconductor substrate 206, it is discharged outside the chamber 201.

  FIG. 5 is a diagram for explaining the problems of the film forming apparatus using the epitaxial growth technique.

  When the unreacted process gas 225 is discharged from the periphery of the semiconductor substrate 206 as described above, the process gas 225 comes into contact with the relative high temperature portion generated in the liner 202 that covers the inner wall of the chamber. A thermal decomposition reaction or hydrogen reduction reaction similar to the surface of the substrate 206 occurs. In that case, as shown in FIG. 5, a silicon crystal 235 derived from the process gas 225 is formed at the corner 234 of the step 232 of the liner 202.

Such formation of the silicon crystal 235 further narrows the gap between the corner portion 234 of the step portion 232 and the peripheral portion of the semiconductor substrate 206, which becomes the flow path of the process gas 225.
As a result, the flow state of the process gas 225 on the surface of the semiconductor substrate 206 during film formation changes. That is, a crystal film cannot be formed on the semiconductor substrate 206 under a uniform flow of the process gas 225.

  Further, the silicon crystal 235 generated here is substantially the same as the vapor phase growth film formed on the surface of the semiconductor substrate 206. Such formation of the silicon crystal 235 causes the liner 202 to be lost when transparency is required.

  When such devitrification of the liner 202 becomes a problem, it can be recovered by cleaning with hydrofluoric acid, for example. However, it is not easy to completely remove the formed silicon crystal. Then, the silicon crystal lump is peeled off due to repeated heating and cooling accompanying the operation of the film forming apparatus 200 and stays in the chamber 201 as particles. And it contaminates the vapor phase growth film formed on the semiconductor substrate produced later, and becomes a factor which reduces quality.

  Therefore, in order to continuously operate the film forming apparatus 200, the above-described silicon crystal 235 must be removed and the inside of the chamber 201 must be kept clean. For this purpose, it is necessary to periodically stop the operation of the film forming apparatus 200 and perform maintenance of the chamber 201.

  This maintenance work requires not only work such as cleaning the inside of the chamber 201 but also preparation of an environment for re-operation, and therefore requires a corresponding time. For example, it takes a considerable amount of time and labor to perform a careful operation noting that the chamber 201 whose interior has been cleaned is not contaminated by outside air, and adjusting the reassembled chamber 201 to a predetermined degree of vacuum. . Therefore, in the film forming apparatus 200 that needs to periodically perform maintenance work for removing particles, there is a problem that the operation rate cannot be improved beyond a certain level.

  As described above, the conventional film forming apparatus 200 has a problem with respect to the quality of the semiconductor substrate to be produced and a problem of a reduction in operating rate caused by work necessary for maintaining the quality.

The present invention provides a film forming apparatus capable of overcoming such problems and preventing formation of by-products in the chamber by a process gas by vapor phase growth, and a film forming method using the same. It is.
Moreover, even if by-product formation occurs on the chamber, the present invention eliminates the formation of the by-product so that the quality of the semiconductor substrate to be produced is not deteriorated and the operating rate of the apparatus is improved compared to the conventional one. And a film forming method using the same.

  Other objects and advantages of the present invention will become apparent from the following description.

  A film forming apparatus of the present invention includes a film forming chamber, a supply unit for supplying a process gas into the film forming chamber, an exhaust unit provided at the bottom of the film forming chamber, a body, and a cross-sectional area from the body. A cylindrical liner that covers the inner wall of the film forming chamber, a cylinder liner that covers the inner wall of the film forming chamber, and a substrate that is provided in the body of the liner. And a susceptor to be mounted. A gas flow path is disposed around the head of the liner so as to supply hydrogen chloride gas into the liner of the film forming chamber.

  And it is preferable that the gas outlet of the gas flow path for supplying hydrogen chloride gas in a liner is provided in the step part of the liner.

  Moreover, it is preferable that the gas outlet of a gas flow path is provided in the step part of the liner so that the circumference | surroundings of the head of a liner may be enclosed.

  The gas flow path is preferably configured to supply hydrogen gas and hydrogen gas into the liner.

  In the film forming method of the present invention, the process gas is allowed to flow from the top of the film forming chamber, and the substrate is placed on a susceptor supported by a rotating cylinder, while the process gas is brought into contact with the substrate and a predetermined film is formed. Form. Then, the inner wall of the film forming chamber is covered with a cylindrical liner composed of a body portion where the susceptor is disposed, a head portion having a smaller cross-sectional area than the body portion, and a step portion connecting the body portion and the head portion. While supplying a gas containing hydrogen chloride gas into the liner from the gas outlet provided in the step of the liner, the process gas flows down from the top of the film formation chamber, and the process gas is brought into contact with the substrate to form a predetermined film. It is characterized by forming.

  According to the film forming apparatus of the present invention, by using hydrogen chloride (HCl) gas supplied into the chamber, it is possible to suppress by-products from adhering to the inner wall of the chamber during the film forming process. . Even if a by-product is generated during the film formation process and the by-product adheres to the inner wall of the chamber, it can be removed using hydrogen chloride (HCl) gas supplied into the chamber. . Therefore, it is possible to manufacture a high quality epitaxial substrate.

  According to the film forming apparatus of the present invention, it is possible to prevent the by-product from adhering to the inner wall of the chamber, facilitate the maintenance work of the film forming apparatus, and improve the operating rate of the film forming apparatus. It becomes possible.

  According to the film forming method of the present invention, by using the hydrogen chloride gas supplied into the chamber, it is possible to suppress the by-product from adhering to the inner wall of the chamber during the film forming process. Even if a by-product is generated during the film forming process and the by-product adheres to the inner wall of the chamber, it can be removed using hydrogen chloride gas supplied into the chamber. Therefore, it is possible to manufacture a high quality epitaxial substrate.

  According to the film forming method of the present invention, it is possible to suppress by-products from adhering to the inner wall of the chamber, to facilitate maintenance work of the film forming apparatus to be used, and to improve the operating rate of the film forming apparatus. It is possible to improve the film forming work efficiency.

It is typical sectional drawing of the film-forming apparatus of this Embodiment. It is a principal part enlarged view of the film-forming apparatus of this Embodiment. It is typical sectional drawing of another example of the film-forming apparatus of this Embodiment. It is typical sectional drawing for demonstrating the structure of the film-forming apparatus using an epitaxial growth technique. It is a principal part enlarged view of the film-forming apparatus for demonstrating the problem of the film-forming apparatus using an epitaxial growth technique.

  FIG. 1 is a schematic cross-sectional view of the film forming apparatus of the present embodiment.

  As shown in FIG. 1, a film forming apparatus 50 according to the present embodiment includes a chamber 1 as a film forming chamber, a hollow cylindrical liner 2 that covers and protects the inner wall of the chamber 1, and cooling that cools the chamber 1. The water flow paths 3a and 3b, the supply part 4 for introducing the process gas 25, the exhaust part 5 for exhausting the process gas after the reaction, and the semiconductor substrate 6 as a substrate such as a silicon wafer are placed on this. A rotating susceptor 7 to be supported, a heater 8 that is supported by a support portion (not shown) and heats the semiconductor substrate 6, a flange portion 9 that connects the upper and lower portions of the chamber 1, a packing 10 that seals the flange portion 9, and an exhaust It has the flange part 11 which connects the part 5 and piping, and the packing 12 which seals the flange part 11. FIG.

  A gas flow path 26 is provided around the hollow cylindrical liner 2, and a gas supply unit 42 is provided on the side wall of the upper portion of the chamber 1. The gas supply unit 42 is connected to the gas flow path 26, and as will be described later, hydrogen chloride (HCl) gas, hydrogen gas, or the like is supplied to the gas flow path 26 provided around the liner 2. The gas 41 can be supplied.

  In addition, hydrogen chloride gas is supplied to the gas supply part 42 from the hydrogen chloride supply part (not shown) which is a hydrogen chloride cylinder, for example. Moreover, hydrogen gas is supplied to the gas supply part 42 from the hydrogen gas supply part (not shown) which is a hydrogen cylinder, for example. These are supplied to the gas flow path 26 independently or mixed.

  A semiconductor substrate 6 is placed on the susceptor 7. The semiconductor substrate 6 is a wafer or the like to be subjected to vapor phase growth. The susceptor 7 that supports the semiconductor substrate 6 is supported by a rotating cylinder 23, and is further connected to a rotating mechanism (not shown) via a rotating shaft 22.

  Specifically, a rotating shaft 22 extending to the inside of the chamber 1 is provided at the bottom of the chamber 1, and a rotating cylinder 23 is disposed at the upper end of the rotating shaft 22, and the rotating cylinder 23 has the above-described susceptor. 7 is attached. Therefore, the susceptor 7 is disposed above the heater 8 and is rotatable inside the chamber 1. During the vapor phase growth reaction, by rotating the susceptor 7, the semiconductor substrate 6 placed thereon rotates at a high speed.

  A reflector 45 is erected on the bottom of the liner 2 of the chamber 1 so as to cover the periphery of the susceptor 7 and the heater 8 on which the semiconductor substrate 6 is placed. The reflector 45 reflects heat from the heater 8 to improve the heating efficiency of the semiconductor substrate 6 placed on the susceptor 7, and excessive temperature around the semiconductor substrate 6 and the heater 8 in the liner 2. It works to suppress the rise. The reflector 45 is preferably made of a member formed by coating SiC (silicon carbide) on carbon (C) so as to have high heat resistance.

  Packings 10 and 12 are used for sealing the flange portion 9 of the chamber 1 and the flange portion 11 of the exhaust portion 5 for sealing. The packings 10 and 12 are made of fluoro rubber, and the heat resistant temperature is about 300 ° C. Therefore, it is particularly effective to provide the cooling water flow paths 3a and 3b for cooling the chamber 1 because the packings 10 and 12 can be prevented from being deteriorated by heat.

  In the film forming apparatus 50, the semiconductor substrate 6 placed on the susceptor 7 in the chamber 1 is rotated by the heater 8 at 1000 ° C. or higher while rotating through the susceptor 7 connected to a rotation mechanism (not shown). To be heated. In this state, a process gas 25 containing a reactive gas is supplied into the chamber 1 from the supply unit 4 through the through hole 21 of the shower plate 20 which is a gas rectifying plate.

A gas 41 is supplied from a gas supply unit 42 in the upper side wall of the chamber 1. The gas 41 includes hydrogen chloride gas, hydrogen gas, or the like.
When a thermal decomposition reaction or a hydrogen reduction reaction occurs on the surface of the semiconductor substrate 6, a crystal film is formed on the surface of the semiconductor substrate 6. At this time, the process gas other than that used in the vapor phase growth reaction becomes a modified product gas, and is sequentially exhausted from the exhaust unit 5 provided in the lower portion of the chamber 1 together with the process gas 25 and the gas 41.

In the film forming apparatus 50, an epitaxially grown film can be formed on the surface of the semiconductor substrate 6 while rotating the semiconductor substrate 6 at a high speed. And it is comprised so that the film-forming speed | rate can be improved by making the process gas 25 contact one after another to the surface of the semiconductor substrate 6 heated uniformly.
Hereinafter, the main components of the film forming apparatus 50 will be described in more detail.

  The hollow cylindrical liner 2 is made of, for example, quartz and has transparency. A shower plate 20, which is a gas rectifying plate, is attached to the upper opening of the head 31 so that the process gas 25 can be uniformly supplied to the surface of the semiconductor substrate 6. The shower plate 20 is provided with a plurality of through holes 21 for supplying the process gas 25.

  In the film forming apparatus 50 of the present embodiment shown in FIG. 1, the through-hole 21 of the shower plate 20 is provided so that the process gas 25 supplied from the supply unit 4 can be uniformly supplied onto the semiconductor substrate 6 on the susceptor 7. Are arranged in a region corresponding to the semiconductor substrate 6.

  The liner 2 is provided because the chamber wall of the film forming apparatus is made of stainless steel. That is, in the film forming apparatus 50, the entire surface of the stainless steel wall is covered with the liner 2 so as not to be exposed in the gas phase reaction system. By doing in this way, the effect which prevents the particle | grains and metal contamination at the time of crystal film formation of the semiconductor substrate 6 surface, or the corrosion of the stainless steel wall of the chamber 1 is acquired.

  The hollow cylindrical liner 2 includes a head portion 31 that supports the shower plate 20 and a body portion 30 in which the susceptor 7 is disposed and a gas phase reaction is performed on the surface of the semiconductor substrate 6 by the process gas 25. Since the inner diameter of the head portion 31 is smaller than the trunk portion 30, the cross-sectional area of the head portion 31 is smaller than that of the trunk portion 30, and the liner 2 has a structure in which the head portion 31 is narrowed.

  As described above, the hollow cylindrical liner 2 has a structure in which the head portion 31 is narrowed down. The semiconductor substrate of the process gas 25 that has passed through the shower plate 20 while supporting the shower plate 20 at the upper opening thereof. This is for the purpose of providing a flow path directed to 6.

  An inner diameter of the narrowed head portion 31 is determined so as to correspond to the arrangement of the through holes 21 of the shower plate 20 and the size of the semiconductor substrate 6. As a result, it is possible to reduce a useless space in which the process gas 25 diffuses after exiting the through hole 21 of the shower plate 20, and the process gas 25 supplied from the shower plate 20 can be used on the surface of the semiconductor substrate 6 without waste. Collectively, the process gas 25 is used efficiently. By improving the shape of the liner 2 in this way, a highly efficient vapor phase growth reaction on the surface of the semiconductor substrate 6 can be realized.

  In the liner 2 having a hollow cylindrical shape, a step 32 derived from the difference in cross-sectional area is formed at the boundary connecting the body 30 and the head 31 having different cross-sectional areas because the inner diameters thereof are different. Yes. The corner portion 34 of the step portion 32 is also a portion where the body portion 30 and the head portion 31 are joined, and the head portion 31 is a root that rises toward the upper side of the chamber 1.

  As described above, the liner 2 includes the trunk portion 30, the head portion 31, and the step portion 32 at the boundary between them. A gap 38 is provided in the vicinity of the corner 34 of the step 32 so as to penetrate the step 32 and surround the rising portion of the head 31. The gap 38 is connected to the gas flow path 26 described above, and constitutes a gas outlet 44 that ejects the gas 41 supplied to the gas flow path 26 as will be described later.

  The liner 2 has a structure in which the lower surface side of the corner portion 34 of the step portion 32 that is the base of the head portion 31 protrudes above the semiconductor substrate 6 and the susceptor 7 so as to eliminate a useless space in which the process gas 25 diffuses. . In other words, the lower surface side of the corner portion 34 is positioned in the vicinity of the semiconductor substrate 6 and the susceptor 7.

  As described above, the gas flow path 26 is provided around the head 31 of the liner 2. Although the head portion 31 of the liner 2 has a cylindrical shape, the gas flow path 26 surrounding the head portion 31 is also formed of a cylindrical wall portion, and a double pipe structure is formed by the head portion 31 of the liner 2 and the gas flow passage 26. It is composed. The gas flow path 26 is connected to a gas supply unit 42 provided on the upper side wall portion of the chamber 1 at the upper portion thereof. Thereby, the gas 41 such as hydrogen chloride gas or hydrogen gas supplied to the gas supply unit 42 is supplied to the gas flow path 26 surrounding the head portion 31 of the liner 2.

  In the lower part of the gas flow path 26, the gas flow path 26 is connected to a gap 38 provided in the step portion 32 of the liner 2 so as to penetrate the step portion 32 and surround the rising portion of the head portion 31. Accordingly, the gap 38 serves as an outlet for the gas 41 supplied to the gas flow path 26 and constitutes a gas outlet 44 through which the gas 41 is ejected.

  At this time, the gas outlet 44 is provided so as to surround the periphery of the head portion 31 of the liner 2, and the gas outlet 44 faces the susceptor 7 with the gap 38 interposed therebetween, and is located in the vicinity immediately above the susceptor 7. It is supposed to be located.

  Next, the arrangement of the gas outlet 44 located immediately above the susceptor 7 and the operation of the gas 41 such as hydrogen chloride gas or hydrogen gas ejected from the gas passage 26 through the gas flow path 26 will be described.

  As described above, in the film forming apparatus 50 of the present embodiment, the liner 2 has a structure in which the so-called head portion 31 is narrowed with respect to the body portion 30.

  Accordingly, the process gas 25 supplied from the supply unit 4 provided at the top of the chamber 1 into the chamber 1 of the film forming apparatus 50 passes through the head portion 31 serving as a flow path toward the surface of the semiconductor substrate 6. It flows down efficiently. At this time, the gap 38 between the peripheral portion of the semiconductor substrate 6 and the liner 2 is configured to be narrow so that the flow of the process gas 25 on the surface of the semiconductor substrate 6 becomes more uniform. Specifically, the gap 38 between the corner portion 34 of the step portion 32 at the boundary between the head portion 31 and the trunk portion 30 of the liner 2 and the peripheral portion of the semiconductor substrate 6 is narrowed.

  Thus, by narrowing the gap 38 between the corner portion 34 of the step portion 32 of the liner 2 and the peripheral portion of the semiconductor substrate 6, after the process gas 25 reaches the vicinity of the semiconductor substrate 6, The speed of flowing out from the surface of the semiconductor substrate 6 to the side of the rotating cylinder 23 that supports the susceptor 7 is increased. In this way, the process gas 25 is prevented from winding up above the head portion 31 of the liner 2.

  However, as described above, one problem occurs here. That is, the radiant heat from the heater 8 is transmitted not only to the semiconductor substrate 6 but also to all members constituting the film forming apparatus 50, and raises the temperature of these members. Such a temperature rise is remarkable in the vicinity of high-temperature portions such as the semiconductor substrate 6 and the heater 8.

  For this reason, a relatively high temperature portion may occur at the boundary between the body 30 and the head 31 of the liner 2 near the semiconductor substrate 6 and the heater 8. In particular, the temperature is extremely high at a portion close to the semiconductor substrate 6 and the susceptor 7, that is, at the corner portion 34 of the step portion 32 at the boundary between the body portion 30 and the head portion 31 of the liner 2.

  As already described, when the process gas 25 configured to include a source gas serving as a silicon source is brought into contact with a relatively high temperature portion generated in the liner 2 on the inner surface of the chamber 1, the same as the surface of the semiconductor substrate 6. Thermal decomposition reaction or hydrogen reduction reaction occurs. Therefore, the silicon crystal 235 derived from the process gas 25 as shown in FIG. 5 is generated at the corner portion 34 of the step portion 32 of the liner 2 in the chamber 1 unless any protective means is applied. Become.

The formation of such silicon crystal is assumed to be a gap 38 between the corner portion 34 of the step portion 32 of the liner 2 and the peripheral portion of the semiconductor substrate 6, which pollutes the liner 2 and serves as a flow path for the process gas 25. It will be narrower than yours.
As a result, the flow state of the process gas 25 at the time of film formation on the surface of the semiconductor substrate 6 changes, and it becomes impossible to form a film on the semiconductor substrate 6 under a uniform flow.

  Therefore, in the film forming apparatus 50 of the present embodiment, the gas outlet 44 is provided at the corner 34 of the step 32 of the liner 2. When hydrogen chloride gas is introduced into the gas supply unit 42, the hydrogen chloride gas is ejected from the gas outlet 44 through the gas flow path 26. As a result, the silicon crystal derived from the process gas 25 can be prevented from adhering to the portion of the liner 2 near the semiconductor substrate 6 and the susceptor 7 heated to a high temperature, that is, the corner portion 34 of the step portion 32 of the liner 2. .

  FIG. 2 is a diagram for explaining the operation of the gas outlet of the film forming apparatus of the present embodiment and the hydrogen chloride gas ejected therefrom. 2, the principal part of the film-forming apparatus 50 shown in FIG. 1 is expanded and shown.

  In the film forming apparatus 50 according to the present embodiment, the semiconductor substrate 6 is placed on the susceptor 7, and the susceptor 7 supports the semiconductor substrate 6 thereby. At this time, as shown in FIG. 2, the gas outlet 44 faces the susceptor 7 with the gap 38 therebetween, and is positioned in the vicinity of the susceptor 7. Accordingly, the gas 41 such as hydrogen chloride gas introduced into the gas flow path 26 is ejected from the gas outlet 44 and is located at the corner portion 34 of the step portion 32 of the liner 2. The gap 38 between the susceptor 7 and the step portion 32. To be released.

  In the gap 38, the denatured gas after being used for forming an epitaxial film on the semiconductor substrate 6 and the reaction of the process gas 25 were not used toward the peripheral edge side of the semiconductor substrate 6 on the susceptor 7. Some gas forms a flow.

  Accordingly, the hydrogen chloride gas released into the gap 38 reacts with a part of the process gas 25 flowing toward the gap 38. As a result, the process gas 25 flowing through the gap 38 touches the corner portion 34 of the step portion 32 that has been heated to a high temperature to cause a decomposition reaction, thereby generating a by-product. Thereby, it is suppressed that a silicon crystal adheres to the corner | angular part 34. FIG.

For example, when the process gas 25 is configured to include a source gas serving as a silicon source, silicon crystals may be generated as a by-product and may adhere to the high temperature portion of the liner 2. It reacts with the flowing source gas to form a gaseous Si _x Cl _y compound, which is discharged from the periphery of the semiconductor substrate 6 on the above-described flow.

  As described above, the gas 41 ejected from the gas outlet 44 in the state where the semiconductor substrate 6 is placed on the susceptor 7, protrudes above the semiconductor substrate 6 and the susceptor 7. The corner 34 is covered and protected.

At this time, the remaining hydrogen chloride gas of the gas 41 that has not been used for the formation reaction of the Si _x Cl _y compound described above is flowed by the process gas 25 and the like, so that it flows toward the center of the semiconductor substrate 6. I will not head. That is, unreacted hydrogen chloride gas rides on the flow of the process gas 25 and the like and is discharged to the peripheral edge side of the semiconductor substrate 6. Therefore, adverse effects on the epitaxial film growth reaction on the semiconductor substrate 6 and undesirable effects on the formed epitaxial film can be avoided.

Further, even if silicon crystals adhere to the vicinity of the corner 34 of the step portion 32 of the liner 2 by the process gas 25 passing through the gap 38, hydrogen chloride gas is introduced while the portion is heated. As a result, the silicon crystal and hydrogen chloride gas react to form a Si _x Cl _y compound. The Si _x Cl _y compound is discharged from the peripheral edge side of the semiconductor substrate 6 along with the flow of the process gas 25.

  Furthermore, the process gas 25 may cause silicon crystals to adhere to the susceptor 7 on which the semiconductor substrate 6 is placed. Such adhesion of silicon crystals to the susceptor 7 is also ejected from the gas outlet 44. The gas 41 is effective. That is, the gas outlet 44 is positioned immediately above the susceptor 7, and the gas 41 ejected from the gas outlet 44 reaches the susceptor 7. Therefore, like the corner portion 34 of the step portion 32 of the liner 2, it can be covered from the process gas 25.

Even if the silicon crystal adheres to the susceptor 7, the susceptor 7 is normally in a high temperature state, and the attached silicon crystal is also at a high temperature, so that the silicon crystal and hydrogen chloride gas react to form Si _x Cl _y. A compound is formed. The Si _x Cl _y compound is discharged from the peripheral edge side of the semiconductor substrate 6 along with the flow of the process gas 25.

  The amount of gas 41 supplied to the gas supply unit 42 and the concentration of hydrogen chloride gas in the gas 41 can be set to desired values depending on the amounts of hydrogen chloride gas and hydrogen gas supplied thereto. . In order not to adversely affect the epitaxial film growth reaction on the semiconductor substrate 6 and to have no undesirable influence on the formed epitaxial film, the amount of the gas 41 ejected from the gas outlet 44 to the gap 38, It is desirable that the concentration of hydrogen chloride gas contained in the gas 41 is determined.

  Next, the film forming method of this embodiment will be described. In this film forming method, the above-described film forming apparatus 50 is used.

  In the film forming apparatus 50, the susceptor 7 is mounted on a rotating cylinder 23 and is connected to a rotating mechanism (not shown) via a rotating shaft 22 so as to be rotatable.

  A hollow cylindrical liner 2 that covers the inner wall of the chamber 1 of the film forming apparatus 50 is provided. The liner 2 that covers the inner wall of the chamber 1 includes a body portion 30 in which the susceptor 7 is disposed, a head portion 31 having a narrowed inner diameter smaller than the body portion 30, and a body portion 30. And a step 32 located at the boundary between the head 31 and the head 31.

  The process gas 25 can efficiently reach the semiconductor substrate 6 on the susceptor 7 using the head portion 31 as a flow path.

A gas supply unit 42 for supplying a gas 41 containing hydrogen chloride (HCl) gas, hydrogen gas, or the like into the chamber 1 is provided on the side wall of the upper portion of the chamber 1.
Chlorine gas is supplied from a hydrogen chloride supply unit (not shown), for example, a hydrogen chloride cylinder, to the gas supply unit 42, and hydrogen gas is supplied from a hydrogen gas supply unit (not shown), for example, a hydrogen cylinder, to the gas supply unit. 42.

A gas flow path 26 is provided around the head 31 of the liner 2. Although the head portion 31 of the liner 2 has a cylindrical shape, the gas flow path 26 surrounding the head portion 31 is also formed of a cylindrical wall portion, and a double pipe structure is formed by the head portion 31 of the liner 2 and the gas flow passage 26. It is composed.
The gas flow path 26 is connected to the gas supply part 42 provided on the side wall of the chamber 1 at the upper part thereof. Therefore, the gas 41 such as hydrogen chloride gas or hydrogen gas supplied to the gas supply unit 42 is supplied to the gas flow path 26 surrounding the head portion 31 of the liner 2.

  Near the corner 34 of the step 32 of the liner 2, a gap 38 is provided so as to penetrate the step 32 and surround the rising portion of the head 31.

  The gas flow path 26 is connected to a gap 38 provided in the step portion 32 of the liner 2 at a lower portion thereof. Accordingly, the gap 38 serves as an outlet for the gas 41 supplied to the gas flow path 26 and constitutes a gas outlet 44 for ejecting the gas 41.

  At this time, the gas outlet 44 is provided so as to surround the periphery of the head portion 31 of the liner 2 as described above, and the gas outlet 44 is located in the vicinity of the position immediately above the susceptor 7.

  Therefore, a gas outlet 44 is formed in the vicinity of the tip of the corner 34 in the step portion 32 of the liner 2, and the gas 41 supplied to the gas supply unit 42 is supplied into the liner 2 from the gas outlet 44. Can do. As a result, the gas 41 ejected from the gas outlet 44 further passes through the gap 38 between the lower surface side of the corner portion 34 of the stepped portion 32 of the liner 2 and the upper surface of the susceptor 7, and thus the side of the semiconductor substrate 6. And the side of the susceptor 7 and finally exhausted out of the apparatus from the bottom of the chamber 1.

  In the film forming method of the present embodiment using the film forming apparatus 50 having the above configuration, the process gas 25 is supplied to the chamber while the chamber 1 is cooled by the flow paths 3a and 3b of the cooling water provided on the outer periphery of the chamber 1. The process gas 25 is introduced from the supply unit 4 provided at the top of 1 and flows down through the through hole 21 of the shower plate 20 which is a gas rectifying plate. A crystal film is formed on the surface of the semiconductor substrate 6 by contacting the process gas 25 while heating the semiconductor substrate 6 placed on the rotary susceptor 7 disposed below.

  At this time, the gas 41 containing hydrogen chloride gas is supplied to the gas supply unit 42. That is, simultaneously with the introduction of the process gas 25 from the supply unit 4 provided at the top of the chamber 1, the supply of the gas 41 containing hydrogen chloride gas is started. While the process gas 25 for forming the epitaxial film on the surface of the semiconductor substrate 6 is being supplied into the chamber 1, the supply of the gas 41 including the hydrogen chloride gas from the gas supply unit 42 is always continued.

  In the gap 38, toward the peripheral edge side of the semiconductor substrate 6 on the susceptor 7, a modified gas that has been used for forming an epitaxial film on the semiconductor substrate 6 or a gas that has not been used for the reaction of the process gas 25. Some form a flow.

  Therefore, when the gas 41 is configured to include hydrogen chloride gas, the hydrogen chloride gas released into the gap 38 reacts with the process gas 25 flowing toward the gap 38. As a result, the process gas 25 flowing through the gap 38 touches the corner portion 34 of the step portion 32 heated to a high temperature to cause a decomposition reaction, thereby forming a by-product, and silicon crystals adhere to the step portion 32. Suppress.

For example, when the process gas 25 is configured to include a source gas serving as a silicon source, silicon crystals may be generated as a by-product and may adhere to the high temperature portion of the liner 2. It reacts with the flowing source gas to form a gaseous Si _x Cl _y compound, which is discharged from the periphery of the semiconductor substrate 6 on the above-described flow.

  Therefore, the cover of the gas 41 ejected from the gas outlet 44 prevents the silicon crystal derived from the process gas 25, which is an impurity in the chamber 1, from adhering to the periphery of the step portion 32 of the liner 2, and the like. A desired crystal film can be formed on the surface of the substrate 6.

  As described above, an epitaxial film having a predetermined thickness is formed on the surface of the semiconductor substrate 6. After the film formation is completed, the supply of the process gas 25 is terminated. At the same time, the supply of the gas 41 from the gas supply unit 42 can be terminated together with the end of the formation of the epitaxial film, but the semiconductor substrate 6 is moved from a predetermined temperature by measurement with a radiation thermometer (not shown). You may make it complete | finish after confirming that it became low.

  For example, along with the end of the formation of the epitaxial film, the supply of the process gas 25 is ended first, and only hydrogen gas as a carrier gas is supplied from the supply unit 4 to the inside of the chamber 1. And supply of the gas 41 containing hydrogen chloride gas is continued with respect to the gas supply part 42, and the ejection of hydrogen chloride gas from the gas outlet 41 is continued.

  At this time, the susceptor 7 immediately after the formation of the epitaxial film is in a very high temperature state, and when a by-product such as a silicon crystal is attached, it reacts with the hydrogen chloride gas from the gas outlet 41 to react with the silicon crystal. Is removed.

  And after by-products, such as a silicon crystal, were removed from the susceptor 7, the gas 41 supplied to the gas supply part 42 is switched to the gas 41 which does not contain hydrogen chloride. For example, it switches to the gas 41 which consists only of hydrogen gas. As a result, the gas flow path 26 and the gas outlet 44 are purged, and the contaminated gas in the chamber 1 is prevented from entering the gas flow path 26 and the susceptor 7 and the semiconductor substrate 6 are cooled.

  When the contaminated gas in the chamber 1 enters the gas flow path 26, the gas 41 containing hydrogen chloride gas is supplied to the gas flow path 26 in the next epitaxial film formation, and at the same time, from the gas outlet 44. It will be ejected. As a result, the contaminated gas pushed out from the gas flow path 26 may adversely affect the formation of the epitaxial film on the semiconductor substrate 6. Therefore, the purge of the gas flow path 26 with hydrogen gas described above is a very important process.

Thereafter, after confirming that the semiconductor substrate 6 has been cooled to a predetermined temperature, the supply of hydrogen gas from the supply unit 4 into the chamber 1 and the supply of hydrogen gas to the gas supply unit 42 are stopped, The semiconductor substrate 6 is carried out of the chamber 1.
Then, the semiconductor substrate 6 after the gas phase reaction is recovered outside the film forming apparatus 50.

  Examples of the semiconductor substrate 6 include a silicon wafer, particularly a 300 mm silicon wafer used for applications such as a power semiconductor. At this time, for example, in a power semiconductor application, a thick film having a thickness of 10 μm or more, most often about 10 μm to 100 μm, is formed on a 300 mm silicon wafer.

The supply flow rate of the process gas 25 supplied from the supply unit 4 to the chamber 1 is, for example, ₂₀ to 100 SLM (standard liter per minute: standard liter per minute) of carrier gas: H ₂ , reactive gas: dichlorosilane ( SiH ₂ Cl ₂ ) is set to 50 sccm (standard cubic centimeter per minutes: standard cc per minute) to 2 SLM, and other dopant gases: diborane (B ₂ H ₆ ) or phosphine (PH ₃ ) are set to be added in a very small amount. . When diborane is introduced as described above, a p-type conductivity film is formed, and when phosphine is introduced, an n-type conductivity film is formed. Then, the pressure in the chamber 1 is controlled to 1333 Pa to normal pressure, for example. The above conditions are satisfied, and vapor phase growth on the semiconductor substrate 6 is started in the chamber 1.

  The susceptor 7 that supports the semiconductor substrate 6 is connected to a rotation mechanism (not shown) via a rotation shaft 22. During the vapor phase growth reaction, the semiconductor substrate 6 placed thereon is rotated at high speed by rotating the susceptor 7. When forming a thick film, it is preferable to increase the rotation speed of the semiconductor substrate 6 during the film formation, for example, about 900 rpm.

  While the semiconductor substrate 6 undergoes the vapor phase growth reaction under the above process conditions, the heater 8 always heats the semiconductor substrate 6 to 1000 ° C. or higher. Therefore, if the temperature of the entire chamber 1 becomes too high, the fluororubber packing 10 that seals the flange portion 9 of the chamber 1 as described above, or the flange that connects the exhaust portion 5 and the exhaust pipe. The packing 12 sealing the part 11 is deteriorated.

  Therefore, for the purpose of suppressing deterioration of the packings 10 and 12, cooling water having a water temperature of about 20 ° C. is circulated through the cooling water flow paths 3a and 3b provided on the outer periphery of the chamber 1 to easily receive heat radiation. The chamber 1 and the packings 10 and 12 are cooled by circulating cooling water.

  Note that the cooling means at this time may be other than water as long as it can effectively remove heat from the film forming apparatus 50 such as air.

  As described above, in the film forming apparatus and the film forming method using the same according to the present embodiment, the accumulation of by-products generated on the liner in the chamber, which has been a problem in the past, is suppressed, and the frequency of maintenance is reduced. By reducing the above, the labor of maintenance work can be reduced and the operating rate of the apparatus to be used can be improved. As a result, semiconductor substrates such as high-quality wafers can be produced by stabilizing the process conditions.

  The present invention is not limited to the above-described embodiments, and can be variously modified and implemented without departing from the scope of the invention.

  That is, the epitaxial growth apparatus has been described as an example of the film forming apparatus of the present invention. However, the present invention is not limited to this, and any apparatus for vapor-depositing a predetermined crystal film on the silicon wafer surface may be used. For example, even a film forming apparatus for growing a polysilicon film can obtain the same effects as those of the present invention.

  In addition, since the SiC crystal film is vapor-phase grown on the surface of the SiC (silicon carbide) substrate, even in a film forming apparatus that requires substrate heating at a higher temperature such as heating at 1650 ° C., the same effect as the present invention is achieved. An effect can be obtained.

FIG. 3 is a schematic cross-sectional view of another example of the film forming apparatus of the present embodiment.
3 is configured such that the head portion 31 of the liner 2 serving as the flow path of the process gas 25 is shortened, and the height of the chamber 1 is correspondingly reduced. Except for this, it has the same configuration as the above-described film forming apparatus 50 shown in FIG. Accordingly, the same reference numerals are used for the purpose and the function and effect portions common to each other for the sake of convenience.

  A film formation apparatus 150 shown in FIG. 3 is a film formation apparatus that uses a SiC substrate as the semiconductor substrate 6 and causes a SiC crystal film to vapor-phase grow on the surface of the SiC substrate. In this film forming apparatus 150, the heater 8 is used for vapor-phase growth of the SiC crystal film on the surface of the substrate, and heating of the substrate at a higher temperature than the above-described film forming apparatus 50 or the like is required, such as heating at 1650 ° C. .

  In the film forming apparatus 150, the head 31 of the liner 2 is the same as the film forming apparatus 50 when the process gas 25 supplied from the supply unit 4 passes through the shower plate 20 and flows down toward the semiconductor substrate 6. A flow path for the process gas 25 is provided. At this time, in the film forming apparatus 150, the substrate 31 is heated at a very high temperature in order to form the SiC crystal film, so that the head 31 of the liner 2 is heated to a very high temperature.

Therefore, when the process gas 25 containing a raw material gas that easily causes a decomposition reaction such as silane (SiH ₄ ) touches the head 31 of the liner 2 that has been heated, the decomposition reaction occurs, and silicon is used as a by-product. Crystals containing it are produced, and by-products adhere to the high-temperature sites.

Therefore, the distance of the flow path to the semiconductor substrate 6 that has passed through the shower plate 20 is preferably shorter, and the head portion 31 of the liner 2 is preferably at a lower height.
In the film forming apparatus 150, adhesion of by-products is suppressed while taking into account securing a space for providing the gas flow path 26 connected to the gas supply unit 42 to which the gas 41 made of hydrogen chloride gas or the like is supplied. Thus, the height of the head portion 31 of the liner 2, that is, the height of the chamber 1 is set.

  In the film forming apparatus 150 having such a structure, the process gas 25 is supplied to the top of the chamber 1 while supplying the gas 41 containing hydrogen chloride gas into the liner 2 from the gas outlet 44 provided in the step portion 32 of the liner 2. The SiC epitaxial film is formed by flowing down from a certain supply unit 4 and bringing the process gas into contact with the semiconductor substrate 6.

  At this time, the gas 41 supplied to the gas supply unit 42 spreads over the entire interior of the gas flow path 26 around the head portion 31 of the liner 2, and then the lower gas outlet 44 is ejected. The hydrogen chloride gas ejected from the gas outlet 44 reacts with the raw material gas contained in the process gas 25 flowing through the gap 38, suppresses by-product adhesion on the liner 2, and is put on the flow of the process gas 25. Thus, it is possible to discharge from the periphery of the semiconductor substrate 6.

  In the film forming apparatus 150, the head 31 of the liner 2 that covers the inner wall of the chamber 1 is preferably made of a member formed by coating SiC on carbon (C) so that it can withstand high temperature conditions. . Similarly, it is preferable to use a member formed by coating the carbon (C) with SiC so that the gas flow path 26 provided around the head 31 of the liner 2 can withstand high temperature conditions.

  Further, the shower plate 20 is preferably made of a quartz material that generates less impurities as a contamination source when the temperature rise during film formation is up to about 800 ° C. In addition, when the temperature rise during film formation exceeds 800 ° C., it has a high heat resistance, and is composed of carbon (C) coated with SiC, or carbon coated with TaC (tantalum carbide). It is preferable to use a member.

  In addition, although descriptions of parts that are not directly required for the present invention, such as apparatus configuration and control method, are omitted, the required apparatus configuration, control method, and the like can be appropriately selected and used. .

  Also, in the drawings shown for explaining the present invention, components other than those necessary for the explanation are omitted, and the scales and the like are appropriately changed so that they can be clearly seen without matching with the original ones. .

  In addition, all the vapor phase growth apparatuses that include the elements of the present invention and can be appropriately modified by those skilled in the art and the shapes of the respective members are included in the scope of the present invention.

1, 201 Chamber 2, 202 Liner 3a, 3b, 203a, 203b Flow path 4, 204 Supply section 5, 205 Exhaust section 6, 206 Semiconductor substrate 7, 207 Susceptor 8, 208 Heater 9, 11, 209, 211 Flange section 10 , 12, 210, 212 Packing 20, 220 Shower plate 21, 221 Through hole 22, 222 Rotating shaft 23, 223 Rotating cylinder 25, 225 Process gas 26 Gas flow path 30, 230 Body 31, 231 Head 32, 232 Stage Part 34, 234 corner part 38 gap 41 gas 42 gas supply part 44 gas outlet 45 reflector 50, 150, 200 film forming apparatus 235 silicon crystal

Claims (4)

A deposition chamber;
A supply unit for supplying a process gas into the film forming chamber;
An exhaust section provided at the bottom of the film formation chamber;
A cylindrical liner that covers the inner wall of the film-forming chamber, comprising a trunk section, a head section having a smaller cross-sectional area than the trunk section, and a step section that connects the trunk section and the head section;
A film forming apparatus provided in a body portion of the liner in the film forming chamber and having a susceptor on which a SiC substrate is placed;
A gas flow path for supplying hydrogen chloride gas into the liner of the film forming chamber is disposed around the head of the liner ,
A film forming apparatus , wherein a gas outlet of the gas flow path is provided at a step portion of the liner and is located immediately above the susceptor . The film forming apparatus according to claim 1 , wherein the gas outlet of the gas flow path is provided at a step portion of the liner so as to surround a periphery of the head of the liner. The film forming apparatus according to claim 1 , wherein the gas flow path is configured to supply a hydrogen chloride gas and a hydrogen gas into the liner. A film forming method for forming a predetermined film by flowing a process gas from the top of a film forming chamber and heating the SiC substrate placed on a susceptor supported by a rotating cylinder while bringing the process gas into contact with the SiC substrate. In
The inner wall of the film forming chamber is a cylindrical liner composed of a body part in which the susceptor is disposed, a head part having a smaller cross-sectional area than the body part, and a step part connecting the body part and the head part. Coat,
While supplying a gas containing hydrogen chloride gas into the liner from a gas outlet provided at a step portion of the liner and positioned immediately above the susceptor , the process gas flows down from the top of the film formation chamber, and the SiC substrate And forming a predetermined film by bringing the process gas into contact therewith.

Images