Vapor phase deposition apparatus and support table

A vapor phase deposition apparatus includes a chamber, a support table arranged in the chamber, and having a first support unit which is in contact with a back side surface of a substrate and on which the substrate is placed and a second support unit which is connected to the first support unit to support the first support unit, a heat source arranged at a position having a distance from a back side surface of the substrate, the distance being larger than a distance between back side surface of the support table and the heat source, and which heats the substrate, a first flow path configured to supply a gas to form a film into the chamber, and a second flow path configured to exhaust the gas from the chamber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vapor phase deposition apparatus and a support table. For example, the present invention relates to a support member (support table) which supports a substrate such as a silicon wafer in an epitaxial growth apparatus.

2. Related Art

In manufacture of semiconductor devices such as an ultrahigh-speed bipolar transistor and an ultrahigh-speed CMOS, a monocrystalline epitaxial growth technique in which an impurity concentration and a film thickness are controlled is absolutely necessary to improve the performance of devices. In epitaxial growth for vapor-growing a monocrystalline thin film on a semiconductor substrate such as a silicon wafer, an atmospheric chemical vapor deposition method is generally used. Depending on cases, a low-pressure chemical vapor deposition (LP-CVD) method is used. A semiconductor substrate such as a silicon wafer is arranged in a reaction chamber. The semiconductor substrate is heated and rotated while keeping a normal-pressure atmosphere (0.1 MPa (760 Torr)) or a vacuum atmosphere having a predetermined degree of vacuum in the reaction chamber. In this state, a silicon source and a source gas containing a dopant such as a boric compound, an arsenic compound, or a phosphorus compound are supplied. On the surface of the heated semiconductor substrate, thermal decomposition or hydrogen reduction reaction of the source gas is performed. In this manner, a silicon epitaxial film doped with boron (B), phosphorous (P), or arsenic (As) is manufactured by deposition (see Japanese Patent Application, Publication No. JP-A-09-194296, for example).

The epitaxial growth technique is also used in manufacture of a power semiconductor, for example, manufacture of an IGBT (Insulate Gate Bipolar Transistor). In the power semiconductor such as the IGBT, a silicon epitaxial film having a thickness of several 10 μm or more is required.

FIG. 25is a top view showing an example of a state in which a silicon wafer is supported by a holder.

FIG. 26is a sectional view showing a section in a state in which the silicon wafer is supported by the holder shown inFIG. 25.

In a holder210(also called a susceptor) serving as a support member for the silicon wafer200, a counterbore hole having a diameter slightly larger than the diameter of the silicon wafer200is formed. The silicon wafer200may be placed to be fitted in the counterbore hole. In this state, the holder210is rotated to rotate the silicon wafer200, so that a silicon epitaxial film is grown by thermal decomposition or hydrogen reduction reaction of a source gas supplied.

In order to uniformly grow a silicon epitaxial film on the substrate, the substrate is heated as described above, and heat escapes through an edge portion of the substrate. For this reason, in particular, the uniformity of the film thickness of the substrate at an edge portion is disadvantageously deteriorated. For this reason, although the support member is devised to be heated, further improvement is desired.

BRIEF SUMMARY OF THE INVENTION

The present invention has as its object to provide a support member to keep the temperature of a substrate edge uniform.

In accordance with embodiments consistent with the present invention, there is provided a vapor phase deposition apparatus including a chamber, a support table arranged in the chamber, and having a first support unit which is in contact with a back side surface of a substrate and on which the substrate is placed and a second support unit which is connected to the first support unit to support the first support unit, a heat source arranged at a position having a distance from a back side surface of the substrate, the distance being larger than a distance between back side surface of the support table and the heat source, and which heats the substrate, a first flow path configured to supply a gas to form a film into the chamber, and a second flow path configured to exhaust the gas from the chamber.

Also, in accordance with embodiments consistent with the present invention, there is provided a vapor phase deposition apparatus including a chamber, a support table arranged in the chamber and formed a first opening which a substrate is placed on its bottom surface, and a second opening what is an annular opening and is located on an outer peripheral side of the first opening and inside an outer peripheral side, a heat source arranged at a position having a distance from the back side surface of the substrate, the distance being larger than a distance between the substrate and the support table, and which heats the substrate, a first flow path configured to supply a gas to form a film into the chamber, and a second flow path configured to exhaust the gas from the chamber.

Further, in accordance with embodiments consistent with the present invention, there is provided a support table for placing a substrate thereon in a chamber held in a vapor phase deposition apparatus, including a first support unit being in contact with the substrate, and a second support portion connected to the first support portion and made of a material having a heat conductivity lower than that of a material used in the first support unit.

DETAILED DESCRIPTION OF THE INVENTION

First Embodiment

Film uniformity is required in process development for a sheet-feeding epitaxial growth apparatus serving as an example of a vapor phase deposition apparatus. It is apparent that as a point which affects the film uniformity, the uniformity of a silicon wafer edge is given. This is a specific phenomenon, which is so-called an edge effect appearing at a wafer edge having several mm and which is different from a phenomenon at a wafer central portion. The phenomenon is very closely related to a temperature distribution, and a temperature distribution near the edge must be preferable. As will be described later, how to increase the temperature of a part of the holder with which the edge is in contact is a key to increase an edge temperature which tends to decrease. The method of heating the holder is devised. The method will be described below with reference to the drawings.

FIG. 1is a conceptual diagram showing a configuration of an epitaxial growth apparatus according to the first embodiment.

InFIG. 1, an epitaxial growth apparatus100serving as an example of a vapor phase deposition apparatus includes a holder (also called a susceptor)110serving as an example of a support table, a chamber120, a shower head130, a vacuum pump140, a pressure control valve142, an out-heater150, an in-heater160, and a rotating member170. A flow path122for supplying a gas and a flow path124for exhausting a gas are connected to the chamber120. The flow path122is connected to the shower head130. InFIG. 1, a configuration required to explain the first embodiment is shown. However, a reduction scale and the like are not conformed to those of an actual apparatus (the same is also applied to the following respective drawings).

The holder110has a first holder112which is arranged on the inside to be in contact with a silicon wafer101serving as an example of a substrate and a second holder114arranged on the outside to be connected to the first holder112. The first holder112serves as an example of the first support unit. The second holder114serves as an example of a second support unit. In the first holder112, a penetrating opening having a predetermined inner diameter is formed. On a bottom surface of a depressed portion116dug from the upper surface side in a predetermined depth at a right angle or a predetermined angle, the silicon wafer101is supported to be in contact with the back side surface of the silicon wafer101.

The second holder114is formed to have a circular periphery. The second holder114is arranged on the rotating member170which is rotated by a rotating mechanism (not shown) about a center line of the plane of the silicon wafer101perpendicular to the plane of the silicon wafer101. The holder110rotates together with the rotating member170to make it possible to rotate the silicon wafer101.

The out-heater150and the in-heater160are arranged on the back surface side of the holder110. The out-heater150and the in-heater160are arranged at a position having a distance from a back side surface of the silicon wafer101. The distance is larger than a distance between back side surface of the holder110and the heaters. The out-heater150can heat the outer peripheral portion of the silicon wafer101and the holder110. The in-heater160is arranged under the out-heater150to make it possible to heat portions except for the outer peripheral portion of the silicon wafer101. Independently of the in-heater160, the out-heater150is arranged to heat the outer peripheral portion of the silicon wafer101to make it easy to escape heat to the holder110. In this manner, a double-heater structure is employed to improve the in-plane uniformity of the silicon wafer101.

The holder110, the out-heater150, the in-heater160, the shower head130, and the rotating member170are arranged in the chamber120. The rotating member170extends from the inside of the chamber120to a rotating mechanism (not shown) outside the chamber120. For the shower head130, a piping extends from the inside of the chamber120to the outside of the chamber120.

The chamber120serving as a reaction vessel is kept at a normal pressure or in a vacuum atmosphere having a predetermined degree of vacuum by the vacuum pump140. In this state, the silicon wafer101is heated by the out-heater150and the in-heater160. With rotation of the holder110, the silicon wafer101is rotated at a predetermined rotating speed. While the silicon wafer101is rotated, a source gas serving as a silicon source is supplied from the shower head130into the chamber120. Thermal decomposition or hydrogen reduction of the source gas is performed on a surface of the heated silicon wafer101. In this manner, a silicon epitaxial film is grown on the surface of the silicon wafer101. A pressure in the chamber120may be adjusted to a normal pressure or a vacuum atmosphere having a predetermined degree of vacuum by using, for example, the pressure control valve142. Alternatively, when the chamber120is used in the normal pressure, the vacuum pump140or the pressure control valve142may not be used. In the shower head130, the source gas supplied from the outside of the chamber120through the piping is discharged from a plurality of through holes through a buffer inside the shower head130. For this reason, the source gas can be uniformly supplied onto the silicon wafer101. Furthermore, the internal pressures and the external pressures of the holder110and the rotating member170are make equal to each other (a pressure of a front-surface-side atmosphere of the silicon wafer101and a pressure of a back surface-side atmosphere of the silicon wafer101are made equal to each other). In this manner, the source gas can be prevented from entering the inside of the rotating member170or the inside of the rotating mechanism. Similarly, a purge gas or the like on the rotating mechanism (not shown) side can be prevented from leaking into the chamber (front-surface-side atmosphere of the silicon wafer101). In this case, the chamber120is exhausted by the vacuum pump140. However, the exhausting means is not limited to the vacuum pump140. Any means which can exhaust the chamber120may be used. For example, when the chamber120may be set at a normal-pressure atmosphere or a vacuum atmosphere having a pressure close to a normal pressure, the chamber120is exhausted by a blower or the like.

FIG. 2is a view showing an example of the appearance of an epitaxial growth apparatus system.

As shown inFIG. 2, an epitaxial growth apparatus system300is entirely surrounded by a housing.

FIG. 3is a diagram showing an example of a unit configuration of the epitaxial growth apparatus system.

In the epitaxial growth apparatus system300, a cassette is arranged on a cassette stage (C/S)310or a cassette stage (C/S)312. The silicon wafer101set in the cassette is conveyed, or “transferred” into a load/lock (L/L) chamber320by a transfer robot350. The silicon wafer101is conveyed from the L/L320into a transfer chamber330by a transfer robot332arranged in the transfer chamber330. The conveyed the silicon wafer101is conveyed into the chamber120of the epitaxial growth apparatus100. A silicon epitaxial film is formed on a surface of the silicon wafer101by an epitaxial growth method. The silicon wafer101on which the silicon epitaxial film is formed is conveyed from the epitaxial growth apparatus100into the transfer chamber330by the transfer robot332again. The conveyed silicon wafer101is conveyed into the L/L chamber320. Thereafter, the transfer robot350returns the silicon wafer101from the L/L chamber320into a cassette arranged on the cassette stage (C/S)310or the cassette stage (C/S)312. In the epitaxial growth apparatus system300shown inFIG. 3, two chambers120and two L/L chambers320for the epitaxial growth apparatus100are arranged. In this manner, a throughput can be increased.

FIG. 4is a sectional view showing an example of a state in which a silicon wafer is supported by a holder.

In the first embodiment, as a material of the first holder112being in contact with a substrate, a material having a heat conductivity higher than that of a material used in the second holder114is used. More specifically, this configuration is designed to make a heat conductivity λ1of the material of the first holder112higher than a heat conductivity λ2of the material of the second holder114. For example, silicon carbide (SiC) is preferably used as the material of the first holder112, and silicon nitride (Si3N4) is preferably used as the material of the second holder114. The ceramic materials such as SiC and Si3N4are used without using metal materials to make it possible to avoid metal contamination. The materials are preferably selected such that the heat conductivity λ1of the material of the first holder112is twice or more the heat conductivity λ2of the material of the second holder114.

As described above, the heat conductivity of the internal member being in contact with the substrate is made high to make the heat conductivity of the external member relatively low, so that heat generated from a heat source is conducted from the first holder112to the silicon wafer101. On the other hand, the second holder114can be suppressed from generating heat. Therefore, heat received from the out-heater150serving as a heat source can be conducted to the silicon wafer101without loading a heater serving as a heating device (heat source). In contrast to this, heat radiated from the silicon wafer101can be prevented from being externally escaped. As a consequence, a temperature near the edge of the silicon wafer101can be more increased, and a temperature distribution near the edge of the silicon wafer101can be kept uniform. As a result, the film thickness uniformity of the edge portion of the silicon wafer101can be improved.

FIG. 5is a sectional view showing another example of the state in which a silicon wafer is supported by a holder.

InFIG. 5, as a material of a first holder212being in contact with the substrate, a material having a heat conductivity λ higher than that of a material used in a second holder214is used. More specifically, this configuration is designed to make a heat conductivity λ1of the material of the first holder212higher than a heat conductivity λ2of the material of the second holder214. The first holder212and the second holder214are connected to each other with a step. In other words, the diameter of an upper portion of the second holder214on the inner peripheral side is decreased to form a projecting portion215extending to the inner peripheral side at a lower portion of an inner peripheral end. More specifically, a depressed portion is formed on the inner peripheral side. On the other hand, the diameter of the first holder212on the outer peripheral side is decreased to form a projecting portion213extending to the outer peripheral side at an upper portion of an outer peripheral end. An arrangement is preferable in which a back surface of the projecting portion213of the first holder212is placed on the bottom surface of the projecting portion215on the inner peripheral side of the second holder214. At the connection positions, the bottom surface of the projecting portion215serving as the depressed portion formed on the inner peripheral side of the second holder214is in reliable contact with the back surface of the projecting portion213on the outer peripheral side of the first holder212placed on the bottom surface. A very small gap is formed between the outer peripheral surface of the first holder212and the inner peripheral surface of the second holder214. This makes it possible to reduce a contact area between the first holder212and the second holder214. For this reason, heat transfer between the first holder212and the second holder214can be made poor. With this configuration, furthermore, heat radiated from the silicon wafer101can be prevented from being externally escaped.

FIG. 6is a sectional view showing still another example of the state in which a silicon wafer is supported by a holder.

InFIG. 6, as a material of a first holder222being in contact with a substrate, a material having a heat conductivity λ higher than that of a material used in a second holder214is used. More specifically, this configuration is designed to make a heat conductivity λ1of the material of the first holder222higher than a heat conductivity λ2of the material of the second holder224. A notched portion is formed on at least one upper surface side of the first holder212and the second holder214at a position which the first holder212and the second holder219are connected to each other. The first holder212and the second holder214are connected to each other by forming a space (notch) therebetween. In other words, the diameter of an upper portion of the second holder224on the inner peripheral side is decreased to form a projecting portion225extending to the inner peripheral side. On the other hand, the diameter of the first holder222on the outer peripheral side is also decreased to form a projecting portion223extending to the outer peripheral side at an outer peripheral end. A distal end face of the projecting portion225is connected to a distal end face of the projecting portion223to connect the first holder222and the second holder224to each other. With this configuration, a contact area between the first holder222and the second holder224can be decreased. For this reason, heat transfer between the first holder222and the second holder224can be made poor. With this configuration, heat radiated from the silicon wafer101can be prevented from being externally escaped.

As for the first holder212and the first holder222, like the first holder112, silicon carbide (SiC) is preferable used as, for example, the material of the first holder112. As for the second holder214and the second holder224, like the second holder114, silicon nitride (Si3N4) is preferably used as a material. Similarly, the materials are desirably selected such that the heat conductivities λ1of the materials of the first holder212and the first holder222are twice or more the heat conductivities λ2of the materials of the second holder219and the second holder224.

In this manner, the heat conductivity of the internal member being in contact with the substrate is increased to relatively decrease the heat conductivity of the external member to make it possible to easily conduct heat received from the out-heater150serving as a heat source to the silicon wafer101. In contrast to this, heat radiated from the silicon wafer101can be prevented from being externally escaped. Furthermore, a heater serving as a heating device (heat source) is not loaded. For this reason, a temperature near the edge of the silicon wafer101can be more increased. Therefore, the temperature distribution near the edge of the silicon wafer101can be kept uniform. As a result, the film thickness uniformity of the edge portion of the silicon wafer101can be improved.

Second Embodiment

In the first embodiment, a material of a holder on which the silicon wafer101is placed is improve to increase the temperature of the wafer edge without loading a heater serving as a heating device. A second embodiment explains a configuration in which the shape of a holder is improved without improving the material of the holder to increase the temperature of a wafer edge without loading a heater serving as a heating device.

FIG. 7is a conceptual diagram showing a configuration of an epitaxial growth apparatus according to the second embodiment.

InFIG. 7, the same configuration as that inFIG. 1is used except for the holder (also called a susceptor)110serving as an example of a support table. In the second embodiment, the same configuration as that in the first embodiment is used except for the configuration of the holder110.

A penetrating opening having a predetermined inner diameter is formed in the holder110shown inFIG. 7. On a bottom surface of a depressed portion116dug from an upper surface side in a predetermined depth at a right angle or a predetermined angle, the holder110is in contact with a back side surface of the silicon wafer101to support the silicon wafer101.

FIG. 8is a conceptual view showing a sectional configuration of a notched holder according to the second embodiment.

FIG. 9is a conceptual top view of the holder shown inFIG. 8.

The holder110is formed to have a circular periphery. The first holder110is arranged on a rotating member170. On the bottom surface of the depressed portion116of the holder110on which the silicon wafer101is placed, notched portions50which are uniformly radially formed at predetermined intervals as shown inFIGS. 8 and 9are formed. More specifically, the notched portions50are formed on the surface of the holder110being in contact with the back side surface of the silicon wafer101. In this manner, the silicon wafer101can directly receive heat radiated from the out-heater150or the in-heater160serving as a heat source through spaces of the notched portions50without passing through the holder110. With the configuration, in particular, radiant heat from the out-heater150or the in-heater160can be easily received by the edge of the silicon wafer101. Furthermore, the notched portions50are formed to make a contact area to the silicon wafer101small. Therefore, an area for radiating heat from the silicon wafer101to the holder110can be decreased. Therefore, an amount of radiated heat can be suppressed. A notched area of the notched portion50is especially preferably set at 30% or more the area of a surface on which the silicon wafer101is placed. In this case, a notch pattern of the notched portion50is not limited to the above-described pattern. A notch pattern having another shape will be explained below.

FIG. 10is a conceptual view showing a sectional configuration of another notched holder according to the second embodiment.

FIG. 11is a conceptual top view of the holder shown inFIG. 10.

In this case, on the bottom surface of the depressed portion116of the holder110on which the silicon wafer101is placed, notched portions52are formed at predetermined intervals as shown inFIGS. 10 and 11. The notched portion52is formed to have a shape uniformly gradually curved from a notch start position in a circumferential direction. The configuration is preferably used. The notched portion is gradually curved from the notch start position in the circumferential direction to make it possible to decrease deviation of a space in which the silicon wafer101is directly heated by the out-heater150or the in-heater160. The notch pattern of the notched portions50shown inFIGS. 8 and 9has some position to which heat is not directly conducted at all in the radial direction of the silicon wafer101. However, when the notch patterns shown inFIGS. 10 and 11are used, positions to which heat is not directly conducted at all in the radial direction can be decreased or eliminated. A notch area of the notched portions52is especially preferably set at 30% or more the area of the surface on which the silicon wafer101is place as described above. In this case, although a pattern having a shape gradually curved from a notch start position in the circumferential direction is used, the pattern is not limited to this shape. For example, the pattern may be sharply bent from a straight line. Any shape which decreases or eliminates portions to which heat is not directly conducted at all in the radial direction may be used.

As described above, notches are formed on a counterbore surface of the holder110on which the silicon wafer101is placed. In this manner, radiant heat from a heater is easily received by the edge of the silicon wafer101. Therefore, the silicon wafer101can be directly heated by the heat source. As a result, the temperature of the wafer edge can be increased. Furthermore, since a contact area between the holder110and the silicon wafer101decreases, heat radiated from the silicon wafer101can be suppressed. Consequently, a temperature distribution near the edge of the silicon wafer101can be kept uniform. For this reason, the film thickness uniformity of the edge portion of the silicon wafer101can be improved.

Third Embodiment

A third embodiment will describe a configuration of a combination between the first and second embodiments.

FIG. 12is a conceptual diagram showing a configuration of an epitaxial growth apparatus according to the third embodiment.

InFIG. 12, the same configuration as that inFIG. 1is used except for the holder (also called a susceptor)110serving as an example of a support table. In the third embodiment, the same configuration as that in Embodiment 1 is used except for the configuration of the holder110.

The holder110has a first holder118(example of a first support unit) being in contact with the silicon wafer101serving as an example of a substrate on the internal side and a second holder114(example of a second support unit) connected to a first holder118on the external side. A penetrating opening having a predetermined inner diameter is formed in the first holder112. On a bottom surface of a depressed portion116dug from the upper surface side in a predetermined depth at a right angle or a predetermined angle, the silicon wafer101is supported to be in contact with the back side surface of the silicon wafer101. The second holder114is formed to have a circular periphery. The second holder114is arranged on a rotating member170.

FIG. 13is a conceptual diagram showing a sectional configuration of a notched holder according to the third embodiment.

FIG. 14is a conceptual top view of the holder shown inFIG. 13.

As in the first embodiment, as a material of a first holder118being in conduct with the substrate, a material having a heat conductivity λ, higher than that of a material used in a second holder214is used. More specifically, this configuration is designed to make a heat conductivity λ1of the material of the first holder118higher than a heat conductivity λ2of the material of the second holder114. For example, silicon carbide (Si3N4) is preferably used as the material of the first holder118. Silicon nitride (Si3N4) is preferably used as the material of the second holder114. The ceramic materials such as SiC and Si3N4are used without using metal materials to make it possible to avoid metal contamination. The materials are preferably selected such that the heat conductivity λ1of the material of the first holder118is twice or more the heat conductivity λ2of the material of the second holder114. The first holder118and the second holder114are preferably connected to each other to decrease a contact area as described inFIGS. 5 and 6.

As described above, the heat conductivity of the internal member being in contact with the substrate is made high to make the heat conductivity of the external member relatively low, so that heat generated from the out-heater150serving as a heat source can be easily conducted to the silicon wafer101. Furthermore, the heater serving as a heating device (heat source) is not loaded. In contrast to this, heat radiated from the silicon wafer101can be prevented from being escaped. In this manner, the temperature near the edge of the silicon wafer101can be further increased.

Furthermore, notched portions50which are uniformly radially formed at predetermined intervals as shown inFIGS. 13 and 14are formed on the bottom surface of the depressed portion116of the first holder118on which the silicon wafer101is placed. More specifically, the notched portions50are formed on the surface of the holder118being in contact with the back side surface of the silicon wafer101. As a consequence, the silicon wafer101can directly receive heat radiated from the out-heater150or the in-heater160serving as a heat source through spaces of the notched portions50without passing through the holder110. With the configuration, in particular, radiant heat from the out-heater150or the in-heater160can be easily received by the edge of the silicon wafer101. Furthermore, as in the second embodiment, the notch area of the notched portions50is especially preferably set at 30% or more of an area of a surface on which the silicon wafer101is place. In this case, a notch pattern of the notched portion50is not limited to the above-described pattern. A notch pattern having another shape will be explained.

FIG. 15is a conceptual view showing a sectional configuration of another notched holder according to the third embodiment.

FIG. 16is a conceptual top view of the holder shown inFIG. 15.

As in the second embodiment, on the bottom surface of the depressed portion116of the holder110on which the silicon wafer101is placed, notched portions52are formed at predetermined intervals as shown inFIGS. 10 and 11. The notched portion52is formed to have a shape uniformly gradually curved from a notch start position in a circumferential direction. The configuration is also preferably used. The notched portion is gradually curved from the notch start position in the circumferential direction to make it possible to decrease deviation of a space in which the silicon wafer101is directly heated by the out-heater150or the in-heater160. With the configuration, positions to which heat is not directly conducted at all in the radial direction can be decreased or eliminated. A notch area of the notched portions52is especially preferably set at 30% or more the area of the surface on which the silicon wafer101is place as described above. In this case, although a pattern having a shape gradually curved from a notch start position in the circumferential direction is used, the pattern is not limited to this shape. The pattern may be sharply bent from a straight line. Any shape which decreases or eliminates portions to which heat is not directly conducted at all in the radial direction may be used. In this case as well, the first holder118and the second holder114are preferably connected to each other to decrease a contact area as described inFIGS. 5 and 6.

In this manner, notches are formed on a counterbore surface of the holder110on which the silicon wafer101is placed, so that radiant heat from a heater is easily received by the edge of the silicon wafer101. Therefore, the silicon wafer101can be directly heated by the heat source. As a result, the temperature of the wafer edge can be increased. Furthermore, since a contact area between the holder110and the silicon wafer101decreases, heat radiated from the silicon wafer101can be suppressed.

As described above, heat received by the holder110from the heater can be easily conducted to the silicon wafer101. In contrast to this, heat radiated from the silicon wafer101can be prevented from being externally escaped. Furthermore, in addition to the effect, the notches are formed on the counterbore surface of the holder110on which the silicon wafer101is placed to make it easy to receive radiant heat from the heater by the edge of the silicon wafer101, so that the temperature of the wafer edge can be further increased. As a result, a temperature distribution near the edge of the silicon wafer101can be kept uniform. Therefore, the film thickness uniformity of the edge portion of the silicon wafer101can be improved.

Fourth Embodiment

In the first embodiment, the holder is divided into two members, a member made of a material having a low heat conductivity is arranged outside to suppress heat radiation. However, a method of suppressing heat radiation is not limited to the method described in the first embodiment. In a fourth embodiment, a method of suppressing heat radiation by decreasing a heat transfer area of a holder will be described.

FIG. 17is a conceptual view showing a sectional configuration of an example of a holder according to the fourth embodiment. The other configurations are the same as those in the first embodiment. A penetrating opening having a predetermined inner diameter is formed in a holder310. On a bottom surface of a depressed portion (opening) dug from the upper surface side in a predetermined depth at a right angle or a predetermined angle, the silicon wafer101is supported to be in contact with the back side surface of the silicon wafer101. On the holder310, an annular groove G (second opening) is formed at a position which is located outside the depressed portion on which the silicon wafer101is placed and inside the outer peripheral end. When the groove G is dug in the central portion of the holder310throughout the circumference, whereby it becomes possible to make a thickness d of the portion where the groove G is formed smaller than the thickness of the internal portion of the groove G. Therefore, a sectional area in the circumferential direction can be decreased. As a result, a heat transfer area can be decreased. Therefore, heat radiation from the silicon wafer101side to the outside (on the rotating member170side) can be suppressed.

Fifth Embodiment

FIG. 18is a conceptual view showing a sectional configuration of an example of a holder according to a fifth embodiment. The other configurations are the same as those in the first embodiment. A holder320has a first holder232being in contact with a silicon wafer101and arranged on the inside and a second holder234connected to the first holder232and arranged on the outside. The first holder232serves as an example of a first support unit. The second holder234serves as an example of a second support unit. A penetrating opening having a predetermined inner diameter is formed in the first holder232. On a bottom surface of a depressed portion dug from the upper surface side in a predetermined depth at a right angle or a predetermined angle, the silicon wafer101is supported to be in contact with the back side surface of the silicon wafer101. The first holder232has an annular projecting portion233extending to the back side (back surface side of the silicon wafer101) on the outer peripheral portion. In the second holder234, an opening which does not penetrate is formed on the inner peripheral side. In this manner, a projecting portion235extending to the inner peripheral side is formed on a lower portion of an inner peripheral end. The first holder232is supported to be in contact with a distal end portion of the projecting portion233on the bottom surface of the opening serving as an upper surface of the projecting portion235. Centering (alignment of a center position) of the first holder232is performed on the side surface of the opening. When the first holder232substantially moves in a horizontal direction, a part of the side surface is brought into contact with the side surface of the opening of the second holder234. Therefore, since the contact portion between the first holder232and the second holder234corresponds to the bottom surface of the opening and the distal end portion of the projecting portion233, a heat transfer area can be decreased. The area of the distal end surface of the projecting portion233is preferably minimized. The area is more decreased to make it possible to further decrease the heat transfer area. Even if the first holder232and the second holder234are in contact with each other, the heat transfer further decreases when a simple combination is designed such that respective parts physically support the other parts. More specifically, when the first holder232is merely placed on a predetermined portion of the second holder234, the heat transfer further decreases. Even though two essentially separated parts are combined to each other, some gap is generated between the contact surfaces of the parts. This physical gap (distance) may be about 10 to 30 μm. For example, it is assumed that the heat conductivities of the materials of the first holder232and the second holder234are given by 0.25 W/mm·K. When a gas entering the gap is an H2gas, the heat conductivity of the H2gas is about 0.0007 W/mm·K. In addition, when the atmosphere becomes almost vacuum, the heat conductivity further decreases with the decrease in pressure. In this manner, when the contact portion has a gap, the specific heat conductivity of the part serving as a solid state is considerably smaller than the heat conductivity of the actual contact portion. Therefore, heat transfer between the first holder232and the second holder234is considerably suppressed. For this reason, heat radiation from the silicon wafer101side to the outside (on the rotating member170side) can be considerably suppressed.

In this case, the upper surface level of the second holder234is desirably equal to the upper surface level of the first holder232or lower than the upper surface level of the first holder232. More specifically, an offset t is desirably set at 0 or more. In this manner, a gas supplied from the upper portion of the silicon wafer101can be smoothly flowed to the outer peripheral side of the silicon wafer101without being delayed.

As in the first embodiment, as the material used in the first holder232, a material having a heat conductivity higher than that of the material used in the second holder234is more preferably used.

Sixth Embodiment

FIG. 19is a conceptual view showing another example of a holder according to a sixth embodiment when the holder is viewed from the above.

FIG. 20is a conceptual view showing a sectional structure of the holder shown inFIG. 19. The other configurations are the same as those in the first embodiment. A holder330has a first holder242(example of a first support unit) being in contact with a silicon wafer101and arranged on the inside and a second holder244(example of a second support unit) connected to the first holder242and arranged on the outside. A penetrating opening having a predetermined inner diameter is formed in the first holder242. On a bottom surface of a depressed portion dug from the upper surface side in a predetermined depth at a right angle or a predetermined angle, the silicon wafer101is supported to be in contact with the back side surface of the silicon wafer101. The first holder242has a plurality of projecting portions248. The projecting portions248are preferably formed at three or more positions. The projecting portions248are preferably arranged at equal angles about an axis of rotation in such a manner as to surround the silicon wafer101when viewed from the above. An opening is formed in the second holder244on an inner peripheral side, and the first holder242is supported to be in contact with a distal end portion of the projecting portion248on a bottom surface of the opening. The first holder242further has a plurality of projecting portions246extending to the outer peripheral side. The projecting portions246are preferably formed at three or more positions. The projecting portions246are preferably arranged at equal angles about an axis of rotation when viewed from the above. When the first holder242substantially moves in a horizontal direction, some of the projecting portions246are brought into contact with the side surface of the opening of the second holder244. In this manner, centering (alignment of a center position) of the first holder242is performed. As described above, the distal end portion of the projecting portions248is in contact with the second holder244to make it possible to decrease a heat transfer area. Therefore, heat radiation from the silicon wafer101side to the outside (on the rotating member170side) can be suppressed.

In this case, the projecting portions246and the projecting portions248may be formed integrally with the first holder242or separately formed as different parts. In particular, when the projecting portions246and the projecting portions248are different parts, only openings may be formed to fix the projecting portions to the first holder242. For this reason, processing for the first holder242is preferably simple.

FIG. 21is a conceptual view showing still another example of the holder according to the sixth embodiment when the holder is viewed from the above.

FIG. 22is a conceptual view showing a sectional configuration of the holder shown inFIG. 21.

The second holder244has an opening on an inner peripheral side and a plurality of projecting portions258formed in the bottom surface of the opening. The second holder244supports the first holder242such that the distal end portion of the projecting portions258is brought into contact with the back surface of the first holder242. In the second holder244, a plurality of projecting portions256extending to the inner peripheral side are formed on the side surface of the opening. When the first holder242substantially moves in a horizontal direction, the projecting portions256are brought into contact with the side surface of the first holder242. More specifically, centering (alignment of a center position) of the first holder242is performed by the projecting portions256. In this case, the projecting portions are arranged on the second holder244side. With this configuration, the same effect as described above can be obtained. The projecting portions256and the projecting portions258may be formed integrally with the second holder244or formed as different parts. In particular, the projecting portions256and the projecting portions258are formed different parts, only openings may be formed to fix the projecting portions to the second holder244. For this reason, processing for the second holder244is preferably simple. InFIG. 23, the projecting portions248may be formed on the first holder242and the projecting portions256may be formed on the second holder244. Or, InFIG. 24, the projecting portions258may be formed on the first holder242and the projecting portions246may be formed on the second holder244.

In the sixth embodiment, the two types of holders are explained. In any type, the holder is divided into two different parts called first and second holders, and the first and second holders are combined to each other. For this reason, as described above, a gap may be generated at the contact portion in a precise sense. Therefore, the specific heat conductivity of the part is considerably higher than the heat conductivity of the actual contact portion. Furthermore, in the sixth embodiment, heat transfer can be considerably suppressed since a target is brought into contact with several projecting portions.

According to the embodiments described above, heat can be made difficult to be transferred to a substrate, or/and heat from the substrate can be made difficult to be escaped. As a result, the temperature of the substrate can be secured. Therefore, a temperature distribution of the substrate edge can be made preferable, and the film uniformity can be improved.

With this configuration, a temperature distribution near the edge can be kept uniform, and epitaxial growth having a size of 60 μm or more which is equal to the thickness of an n-type base having excellent film uniformity can be achieved.

As a matter of cause, the present invention can be applied to formation of epitaxial layers of thick bases of not only an IGBT, but also a power MOS which is a power semiconductor and requires a high withstand voltage or a GTO (gate turn-off thyristor) used as a switching element for an electric train or a general thyristor (SCR).

The embodiments are described with reference to the concrete examples. However, the present invention is not limited to the concrete examples. For example, an epitaxial growth apparatus is described as an example of a vapor phase deposition apparatus. However, the vapor phase deposition apparatus is not limited to the epitaxial growth apparatus. Any apparatus to perform vapor phase deposition of a predetermined film on a sample surface may be used. For example, an apparatus which grows, e.g., a polysilicon film may be used.

Parts such as apparatus configurations and control methods which are not directly required to explain the invention are omitted. However, required apparatus configurations or required control methods can be appropriately selected and used. For example, although the configuration of the control unit for controlling the epitaxial growth apparatus100is omitted, a required control unit configuration may be appropriately selected and used as a matter of course.

All vapor phase deposition apparatuses and all shapes of support members which include the elements of the present invention and can be appropriately changed in design by a person skilled in the art are included in the spirit and scope of the invention