JP2010263112A - Epitaxial growth device and method for manufacturing silicon epitaxial wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epitaxial growth device for suppressing reverse flow of a gas and improving the uniformity of film thickness distribution of an epitaxial film formed on the surface of a wafer. <P>SOLUTION: The epitaxial growth device 1 includes: a chamber 10 equipped with a gas flow path 2 in the inside and a susceptor 13 for holding the wafer W and provided in the gas flow path 2; and a plurality of gas supply holes 22 disposed on an upstream side of the gas flow path 2 and juxtaposed in a direction across the gas flow path 2. In the device, the position of the gas supply holes 22 which is a height direction of a normal line of the wafer W is set for each of the gas supply holes 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an epitaxial growth apparatus using a vapor phase growth method, and more particularly to a technique suitable for use in uniforming in-plane characteristics such as surface flattening in an epitaxial film.

  In the field of semiconductor manufacturing, an epitaxial wafer in which an epitaxial film is grown on a silicon substrate is conventionally known. An epitaxial wafer can form an epitaxial film having an arbitrary thickness and resistance on a substrate, and can solve a grow-in defect problem that hinders device fabrication.

  In addition, the demand for miniaturization of semiconductor devices is increasing year by year, and the quality of epitaxial wafers used in connection therewith is also demanded. In particular, the uniformity of the epitaxial film thickness or the flatness or flatness of the surface of the epitaxial film is an important requirement and has a great influence on the lithographic process. In addition, when manufacturing a large number of devices from a single wafer, it is important to maintain the quality over a wide range on the wafer. In recent years, it has been included up to the vicinity of the wafer outer periphery (about 3 to 5 mm from the side of the wafer). Management has become necessary. In addition, when epitaxially forming a plurality of wafers by the same batch process, it is important that the uniformity of the epitaxial film characteristics between the plurality of wafers or the non-uniformity on the wafer surface before the epitaxy is made uniform. is there.

Vapor phase epitaxy is often used for epi-growth of silicon wafers. Silane gases (SiH ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , SiCl ₄ ) are used as source gases, and H ₂ is used as a carrier gas. Many.

  As techniques for improving the uniformity in film characteristics such as the flatness of the epitaxial film, for example, those described in Patent Documents 1 and 2 are known.

In the technique of Patent Document 1, two systems of gas supply are provided so that the gas supply is changed between the central portion and the peripheral portion of the wafer. That is, two main gas inlets are set to flow in the center of the wafer and the outer periphery of the wafer, and the gas flow rate in the furnace is controlled by adjusting the gas flow rate independently. A technique for making the epitaxial film thickness distribution uniform is mainly taken.
In the technique disclosed in Patent Document 2, raw material gas and the like are supplied by a plurality of nozzles.

Japanese Patent Laid-Open No. 06-232060 JP 2002-043230 A JP 2007-012664 A

  It is known that epitaxial growth is usually performed under a supply rate-controlled condition by heating a wafer to a high temperature, so that the epitaxial film thickness is easily affected by the flow velocity of gas flowing over the wafer.

  In this regard, conventionally, a plurality of small-diameter holes are arranged at the main gas inlets in two lines along the direction crossing the gas flow path, and the main gas rectified by passing through these small-diameter holes is laminar. In general, a method of introducing into the chamber is generally used. Further, in order to further improve the uniformity of the film thickness distribution, it is necessary to adjust the flow velocity distribution of the gas flow on the wafer surface. As a method of adjusting the distribution of the flow velocity, there is a method of individually adjusting the opening / closing degrees of a plurality of small diameter holes. (Patent Document 3)

  However, when the opening / closing degree of the small-diameter hole is adjusted in this way, if the opening / closing degree of the adjacent small-diameter holes is extremely different, the gradient of the gas flow velocity in the direction orthogonal to the gas flow (wafer radial direction) increases. In some cases, a reverse flow of the gas flow may occur in the chamber. When such a backflow occurs, the gas flow that was in a laminar flow state in the chamber is changed to a turbulent flow, and the distribution of the gas flow is disturbed and the control of the film forming state is disturbed. For example, the film thickness distribution is not uniform. A defect in epitaxial growth occurs. In addition to this, there is a problem that the deposition gas in the furnace increases due to the turbulence of the gas flow and the deposition gas reaches a place other than the furnace wall or the wafer surface where the deposition is not required. There was a case.

  The present invention has been made in view of such problems, and an epitaxial growth apparatus capable of suppressing the backflow of a gas flow and improving the film thickness distribution control characteristics of an epitaxial film formed on the wafer surface, and It aims at providing the manufacturing method of a silicon epitaxial wafer.

In order to solve the above problems, the present invention proposes the following means.
That is, the epitaxial growth apparatus according to the present invention includes a chamber in which a gas flow path is provided and a susceptor for holding a wafer is provided in the gas flow path, and an upstream side of the gas flow path of the chamber. And an epitaxial growth apparatus comprising a plurality of gas supply holes arranged in parallel in a direction crossing the gas flow path, each of the plurality of gas supply holes having a height direction position that is a normal direction of the wafer, The gas supply holes are individually set.

The inventor of the present application has found the following points by diligent efforts.
The “diffusion flux from the gas phase to the wafer surface” that determines the growth degree or film thickness of the epitaxial film is inversely proportional to the boundary layer thickness on the wafer surface of the gas flow. Therefore, if the boundary layer thickness can be controlled, the film thickness distribution of the epitaxial film can be adjusted. Here, the boundary layer thickness is inversely related to the gas flow velocity on the wafer surface. If the gas flow velocity is large, the boundary layer thickness is small. Conversely, if the gas flow velocity is small, the boundary layer thickness is large. . Therefore, if the gas flow rate on the wafer surface can be arbitrarily adjusted, the boundary layer thickness can be controlled, and thereby the film thickness distribution of the epitaxial film can be adjusted.

In view of this point, in the epitaxial growth apparatus of the present invention, the positions of the plurality of gas supply holes in the height direction are individually set. For this reason, the flow velocity on the wafer surface of the gas flow supplied from each gas supply hole can be individually set to adjust the gas flow velocity distribution.
That is, if the gas supply hole has a low height position, it is closer to the wafer surface, so the flow rate of the gas flow by the gas supply hole on the wafer surface becomes large. By increasing the gas flow rate in this way, the boundary layer thickness can be set small, the diffusion flux from the gas phase to the wafer surface in the gas flow can be increased, and the growth degree of the epitaxial film, that is, the film thickness can be set large. it can.
On the other hand, if the gas supply hole has a high height, it is away from the wafer surface, so that the flow velocity of the gas flow through the gas supply hole on the wafer surface is small. By reducing the gas flow rate in this way, the boundary layer thickness can be set large, the diffusion flux from the gas phase to the wafer surface in the gas flow can be lowered, and the growth degree of the epitaxial film, that is, the film thickness can be set small. it can.
In other words, if you want to reduce the film thickness setting for epitaxial film formation, set the gas supply port height position away from the wafer surface, and if you want to increase the film thickness setting for epitaxial film formation, set the gas supply port height. The position can be set in a direction close to the wafer surface.

As described above, in the epitaxial growth apparatus of the present invention, the gas flow velocity distribution on the wafer surface in the flow path cross-sectional direction (the wafer radial direction perpendicular to the flow velocity direction) along the wafer in-plane direction in the chamber. Since it can be set according to the height position of the supply hole, the film thickness distribution of the epitaxial film formed on the wafer can be adjusted.
In addition, unlike the configuration in which the gas supply holes are opened and closed, the flow rate and the flow velocity of the gas flow supplied from the adjacent gas supply holes are not greatly different, so that the backflow of the gas flow in the chamber can be suppressed. . Therefore, the gas flow does not transition to a turbulent flow, and a laminar flow state is maintained in the chamber at least near the wafer surface, and the gas flow can be circulated stably.

  In the epitaxial growth apparatus of the present invention, the position of the gas supply hole in the height direction, which is the normal direction of the wafer, is the thickness distribution of the epitaxial film formed on the wafer as the gas supply hole having a uniform height. The gas flow is controlled so as to compensate for the film thickness distribution of the epitaxial film.

  According to the epitaxial growth apparatus having such characteristics, by setting the height of each gas supply port so as to compensate for the film thickness distribution as described above, the epitaxial growth apparatus can be arranged in a direction perpendicular to the gas flow path in the epitaxial growth apparatus. The film must be formed in accordance with the variation of the epitaxial film thickness due to the gas flow from each gas supply port generated or the in-plane uneven distribution existing on the surface of the wafer to be processed which is to be processed. A gas flow velocity distribution for compensating the epitaxial film thickness that must be formed can be formed on the wafer surface. This makes it possible to improve in-plane uniformity in film properties such as the epitaxial film surface flatness of the wafer.

  Furthermore, the epitaxial growth apparatus of the present invention is characterized in that the position of the gas supply hole in the height direction which is the normal direction of the wafer is variable.

According to the epitaxial growth apparatus having such characteristics, the height of each gas supply hole can be arbitrarily changed according to the size and arrangement of the wafer. Therefore, the wafer thickness after epitaxial film formation can be made uniform corresponding to each wafer.
Further, as a means for reducing the occurrence of film thickness distribution in the epitaxial growth apparatus, for example, an epitaxial film is grown on the wafer surface with the height position of the gas supply holes made uniform, and the film thickness of the epitaxial film is measured to compensate. The thickness of the power epitaxial film can be recognized and recognized. Then, by changing the height position of each gas supply hole so that a gas flow capable of compensating the film thickness of such an epitaxial film can be formed in the gas flow furnace, the epitaxial film characteristics of the wafer are made uniform. Can be sexual.

  The epitaxial growth apparatus of the present invention is characterized in that the gas flow supply direction of the gas supply hole is variable along the wafer normal direction.

Thereby, the fine adjustment of the speed of the gas flow supplied on a wafer surface can be aimed at, and the epitaxial film thickness uniformity of a wafer can be improved more. The arrangement of the gas supply holes is fixed in the direction in the wafer plane in a direction perpendicular to the gas flow, and the gas flow supply direction, that is, the gas ejection direction can be made variable in the vertical direction.
As a result, as in the case of changing the height position of the gas ejection port while ejecting gas in the gas flow path direction parallel to the wafer surface, if the ejection direction is a downward gas supply hole, that is all. Since it is close to the wafer surface, the flow velocity of the gas flow by the gas supply hole on the wafer surface becomes large. By increasing the gas flow rate in this way, the boundary layer thickness can be set small, the diffusion flux from the gas phase to the wafer surface in the gas flow can be increased, and the growth degree of the epitaxial film, that is, the film thickness can be set large. it can.
On the contrary, if the gas supply hole has an upward jet direction, it is away from the wafer surface, so that the flow velocity of the gas flow through the gas supply hole on the wafer surface is small. By reducing the gas flow rate in this way, the boundary layer thickness can be set large, the diffusion flux from the gas phase to the wafer surface in the gas flow can be lowered, and the growth degree of the epitaxial film, that is, the film thickness can be set small. it can.
In other words, if you want to reduce the film thickness setting for epitaxial film formation, set the gas supply port ejection direction away from the wafer surface, and if you want to increase the film thickness setting for epitaxial film formation, The direction can be set to a direction close to the wafer surface.

  Furthermore, in the epitaxial growth apparatus of the present invention, a horizontal distance between the gas supply hole and the wafer along the wafer surface is set in a range of 10 to 50 cm.

The gas flow supplied from the gas supply hole does not immediately become a laminar flow state in the chamber, but is in a laminar flow state in the movement process after reaching the wafer surface after being supplied and ejected into the chamber. Transition to. Therefore, it is necessary to ensure a certain distance between the gas supply hole and the wafer. On the other hand, if the distance between the gas supply hole and the wafer is too large, the flow velocity of the gas flow on the wafer surface is extremely attenuated, and a gas flow having a desired flow velocity can be circulated on the wafer surface. It becomes difficult.
In this regard, according to the epitaxial growth apparatus of the present invention, since the distance in the horizontal direction between the gas supply hole and the wafer is not less than the lower limit of the above range, the gas flow is surely layered before reaching the wafer surface. It is possible to transition to a flow state. In addition, since the horizontal distance between the gas supply hole and the wafer is not more than the upper limit of the above range, a gas flow having a desired flow rate can be circulated on the wafer surface. Therefore, an appropriate gas flow velocity distribution can be formed on the wafer surface, and the epitaxial film thickness can be effectively uniformed.

The method for producing a silicon epitaxial wafer of the present invention is a method for producing a silicon epitaxial wafer by any of the above-described apparatuses,
The boundary layer thickness in the gas flow in the wafer in-plane direction perpendicular to the gas flow channel in the gas flow channel for flowing the film forming gas is set to a height position in the wafer normal direction of the gas supply hole, or the gas It is possible to control the thickness distribution in the wafer surface of the epitaxial film by controlling the direction of the height direction of the gas ejection direction from the supply hole.

  According to the epitaxial growth apparatus and the method for producing a silicon epitaxial wafer of the present invention, the positions in the height direction of the plurality of gas supply holes (including the inclination of the ejection direction in the height direction) are individually set, The flow rate of the gas flow supplied from each gas supply hole on the wafer surface can be individually set. As a result, the gas flow velocity distribution on the wafer surface can be controlled, and the reverse flow of the gas flow in the chamber can be suppressed to maintain the laminar state of the gas flow. Therefore, it is possible to make the film thickness distribution of the epitaxial film formed on the wafer uniform.

1 is a schematic side sectional view showing an epitaxial growth apparatus according to an embodiment. FIG. 2 is a view in the y direction arrow showing the vicinity of a gas supply hole in FIG. 1. It is an expanded sectional side view of the gas rectification member in FIG. FIG. 2 is a schematic cross-sectional view showing the epitaxial growth apparatus according to the embodiment as viewed in the x direction in FIG. 1. It is the front view which looked at the gas supply port in FIG. 2 from the y direction when the height position of a gas supply port is made uniform. It is the front view which looked at the gas supply port in FIG. 2 of the epitaxial growth apparatus which concerns on embodiment from the y direction. It is an enlarged view of the gas rectification member when the gas supply direction of the gas supply hole is inclined. It is an enlarged view of the gas rectifying member in which the gas supply hole is variable in the vertical direction. It is an enlarged view of the gas rectifying member in which the gas supply direction of the gas supply hole is variable. It is a graph which shows the relationship with the epitaxial film thickness with respect to the distance from a wafer center.

Embodiments of an epitaxial growth apparatus according to the present invention will be described below in detail with reference to the drawings.
As shown in FIG. 1, the epitaxial growth apparatus 1 includes a chamber 10 in which a gas flow path 2 is formed, an upstream flange 11, a downstream flange 12, a susceptor 13, an upstream bottom shield 14, and a downstream. A side bottom shield 15, a coil 16, a gas rectifying member 20, and a transfer chamber 17 are provided.

  The chamber 10 has a substantially rectangular tube shape made of transparent quartz, and is arranged with both end openings directed in the horizontal direction. An upper surface of the inner surface of the chamber 10 is a top surface 10a extending along a horizontal plane, and a lower portion thereof is a bottom surface 10b extending similarly along the horizontal plane. And between these top surface 10a and bottom surface 10b which are parallel to each other, a gas flow path 2 having one end side (left side in FIG. 1) as an upstream side and the other end side (right side in FIG. 1) as a downstream side. Is formed.

  The upstream flange 11 is a plate-like member fixed to one end side of the chamber 10 on the upstream side of the gas flow path 2 so as to protrude from the outer periphery of the chamber 10, and is made of stainless steel. . A rectangular hole 11 a penetrating along the direction of the gas flow path 2 is formed in the center of the upstream flange 11. The rectangular hole 11 a has a rectangular shape smaller than the cross-sectional shape orthogonal to the gas flow path 2 on the inner surface of the chamber 10, and thereby, the space between the top surface 10 a and the rectangular hole 11 a of the chamber 10 and the chamber 10. Steps are formed between the bottom surface 10b and the rectangular hole 11a.

  The downstream flange 12 is a plate-like member fixed to the other end side of the chamber 10 on the downstream side of the gas flow path 2 so as to protrude from the outer periphery of the chamber 10, and is made of stainless steel. Yes. A concave portion 12 a that is recessed so as to face the inside of the chamber 10 is formed at a substantially central portion of the surface on the chamber 10 side of the downstream flange 12.

  The recess 12a is provided with an exhaust shield 30 extending so as to be flush with the surface of the downstream flange 12 on the chamber 10 side so as to close the opening. A small-diameter communication hole 30a is formed at a position corresponding to the opening center of 12a.

  An outlet shield 31 is provided in the recess 12a whose opening side is closed by the exhaust shield 30 so as to cover the entire inner wall surface. Furthermore, one end of a discharge path 12b extending toward the inside and outside of the chamber 10 is connected to the bottom of the recess 12a. 31 and the discharge path 12b are in communication.

The susceptor 13 has a substantially disk shape having a recess on which the wafer W is placed on the upper surface, and is disposed along a horizontal plane so as to separate the upstream side and the downstream side of the gas flow path 2. The susceptor 13 may be made of, for example, carbon, and a SiC film may be formed on the upper surface on which the wafer W is placed.
The center of the lower surface of the susceptor 13 is supported by a susceptor support portion 13a extending along the vertical direction. The susceptor support portion 13a is connected to a rotation drive mechanism (not shown) provided outside the chamber 10. As a result, the susceptor 13 rotates as the susceptor support portion 13a rotates.

Further, a susceptor receiving portion 13 b is interposed between the susceptor 13 and the bottom surface 10 b of the chamber 10. The susceptor receiving portion 13b has a substantially dish shape having an edge, the upper surface of the susceptor receiving portion 13b is opposed to the lower surface of the susceptor 13 via a gap, and the edge forming an annular shape is spaced from the outer peripheral surface of the susceptor 13. It is made to oppose through. Further, a through-hole through which the susceptor support portion 13a is inserted is formed at the center of the susceptor receiving portion 13b.
In this way, the susceptor receiving portion 13b accommodates the susceptor 13 through the gap.

The upstream bottom shield 14 is disposed on the bottom surface 10 b in the chamber 10 so as to cover the bottom surface 10 b on the upstream side of the gas flow path 2 with respect to the susceptor 13. The height of the upper surface of the upstream side bottom shield 14 is set to be substantially the same as the height of the upper surface of the wafer W placed on the susceptor 13, and is thereby flush with the upstream side bottom shield 14. The gas flow flowing above is smoothly guided onto the wafer W.
Further, the lower surface side bottom shield 15 is disposed on the bottom surface 10 b in the chamber 10 so as to cover the bottom surface 10 b on the downstream side of the gas flow path 2 with respect to the susceptor 13.
The upstream side bottom shield 14 and the downstream side bottom shield 15 have a role of protecting the bottom surface 10b of the chamber 10 in which they are disposed from deposits.

  A coil 16 is concentrically arranged inside the susceptor 13 and heats the susceptor 13 by induction heating. Further, the top surface 10a, the bottom surface 10b, and the side surface 10c in the chamber are subjected to gold plating coating on the surface, and the structure is such that the radiant heat does not easily escape to the outside.

  The gas rectifying member 20 is a substantially plate-like member fixed to the surface of the upstream flange 11 opposite to the surface on the chamber 10 side, and has a substantially rectangular wafer transfer hole 21 at the center thereof. Is formed. The wafer transfer hole 21 has a substantially rectangular shape smaller than the rectangular hole 11 a of the upstream flange 11, whereby a step portion is formed between the rectangular hole 11 a and the wafer transfer hole 21. Note that when the epitaxial film is grown, the wafer transfer hole 21 is closed by the closing member 21a, whereby the chamber 10 is hermetically sealed.

As shown in detail in FIG. 2, a plurality of gas supply holes 22 are opened on the surface facing the chamber 10 side of the gas rectifying member 20 corresponding to the step between the rectangular hole 11 a and the wafer transfer hole 21. Yes.
These gas supply holes 22 are opened so as to be juxtaposed along a direction transverse to the gas flow path 2, that is, in a horizontal direction perpendicular to the gas flow path 2. As shown in FIG. 3, the gas rectifying member 20 is perforated so as to penetrate the upper surface and the surface facing the chamber 10 in a substantially L shape. Gas is introduced into the gas supply hole 22 from the upper side of the gas rectifying member 20 so that the gas is supplied in a horizontal direction from the opening of the surface facing the chamber 10 into the chamber 10. It has become. The shape of each gas supply hole 22 is set so that the gas flow supplied from the gas supply holes 22 into the chamber 10 is parallel in the wafer in-plane direction parallel to the gas flow path 2.

  The horizontal distance L between the opening of each gas supply hole 22 on the surface of the gas rectifying member 20 facing the chamber 10 and the wafer W is set in the range of 10 cm to 50 cm in this embodiment. .

The upstream side of the gas supply hole 22 is connected to an in-side introduction pipe 23 and a pair of out-side introduction pipes 24 as shown in FIG.
The in-side introduction pipe 23 is branched and connected to a plurality of gas supply holes 22 arranged on the inner side among the gas supply holes 22 (not shown in FIG. 4) arranged in parallel in the direction crossing the gas flow path 2. The pair of out-side introduction pipes 24 are branched and connected to a plurality of gas supply holes 22 located on both outer sides of the gas supply holes 22 connected to the in-side introduction pipe 23.
An in-side flow rate regulator 25 and an out-side flow rate regulator 26 are respectively provided upstream of the branched portions of the in-side introduction pipe 23 and the out-side introduction pipe 24.
The in-side introduction pipe 23 and the out-side introduction pipe 24 are branched from a gas introduction pipe 27 connected to a gas supply means (not shown).

The transfer chamber 17 is a sealed space provided on the surface of the gas rectifying member 20 opposite to the chamber 10 and communicates with the inside of the chamber 10 only when the wafer transfer hole 21 of the gas rectifying member 20 is opened. State.
The inside and outside of the transfer chamber 17 can be opened and closed by a shutter (not shown). Only when a cassette in which a plurality of wafers W are stacked and stacked is placed outside the shutter, the inside of the cassette and the inside of the transfer chamber 17 can be opened. The shutter is opened to establish a communication state. Then, the wafer W is taken out from the cassette by an arm (not shown) installed in the transfer chamber 17, transferred into the chamber 10 in a communication state, and placed on the susceptor 13.

  Here, in the gas rectifying member 20 of the present embodiment, the position H in the height direction of the openings of the plurality of gas supply holes 22 arranged in parallel in the direction crossing the gas flow path 2, that is, these gas supply holes. The position H in the normal direction of the upper surface of the wafer W with 22 openings is set individually.

  Specifically, as shown in FIG. 5, the gas supply port 22 ′ having a uniform height position H in the height direction of the opening of each gas supply hole 22 in the normal direction (vertical direction) of the wafer W. Compensating the film thickness distribution of the epitaxial film formed on the wafer W, the gas flow rate can be controlled so that film characteristics such as flatness in the epitaxial film to be formed are uniform in the wafer W plane, It is set corresponding to the film thickness distribution of the epitaxial film.

That is, first, as shown in FIG. 5, the gas supply holes 22 ′ having the same positions in the height direction of the openings are used as a basic example, and the gas is supplied into the chamber 10 through the gas supply holes 22 ′ of the basic example. An epitaxial film is grown on the upper surface of W. In this basic example, the height position of the gas supply hole 22 ′ is set to H ₀ with reference to the upper surface of the wafer W (or the upper surface of the upstream bottom shield 14).
As shown in FIG. 10, the epitaxial film thickness distribution is taken as the vertical axis, and the arrangement direction of the gas supply holes 22 ′ (the direction crossing the gas flow path 2), that is, the wafer W diameter direction is taken as the horizontal axis. Then, a graph of the film thickness distribution of the basic epitaxial film is drawn.
In FIG. 10, the vertical axis represents the epitaxial film thickness (μm), and the horizontal axis represents the distance (mm) from the wafer center.

And the height position H of each gas supply hole 22 of embodiment is determined according to the curve C which turned the graph curve of the film thickness distribution of the epitaxial film of this basic example upside down. At this time, as shown in FIG. 6, the height position H _av of average of each gas supply holes 22, the high of the gas supply holes 22 so as to match the height H ₀ of the gas supply holes 22 of the basic example It is preferable to determine the position H.
Thereby, the height position of each gas supply hole 22 is set to a height position H at which a gas flow having a flow rate necessary for compensating the film thickness distribution of the epitaxial film can be supplied.

  When an epitaxial film is grown on the wafer W surface in the epitaxial growth apparatus 1 configured as described above, after the wafer W is placed on the susceptor 13 from the transfer chamber 17 as described above, the wafer is closed by the closing member 21a. The transport hole 21 is closed. Then, when the susceptor support portion 13a rotates around the axis, the susceptor 13 and the wafer W on the upper surface thereof are rotated at a predetermined rotational speed in the susceptor receiving portion 13b.

Next, a silane-based gas (SiH ₄ , SiCl ₂ H ₂ , SiHCl ₃ , SiCl ₄ ) and a carrier gas H _{2 that} are source gases (film formation gas) and a carrier gas H ₂ are introduced from the gas introduction pipe 27, and the in-side introduction pipe 23, out After branching to the side introduction pipe 24, the gas flow rate is adjusted by the in-side flow rate regulator 25 and the out-side flow rate regulator 26. Thereafter, the gas passes through the gas supply hole 22 of the gas rectifying member 20 and is introduced into the chamber 10, passes through the upper surface of the upstream bottom shield 14, and then flows on the wafer W surface. At this time, a gas flow is formed at a position in the wafer in-plane direction in parallel with the gas flow path 2 corresponding to one horizontal direction of each gas supply hole 22 and corresponding to the height position of each gas supply hole 22. A boundary layer is formed on the wafer W surface by the gas flow supplied from each gas supply hole 22. The thickness of this boundary layer corresponds to the gas flow velocity on the wafer W surface.

In this state, when the susceptor 13 and the wafer W placed on the upper surface thereof are heated by induction heating, and gas passes through the gas flow path 2 on the wafer W surface, epitaxial growth occurs on the wafer W, and the epitaxial film becomes It is formed.
The gas flow that has flowed to the downstream side of the chamber 10 reaches the exhaust shield 30 and is introduced into the outlet shield 31 in the communication hole 30a of the exhaust shield 30, and is discharged from the communication hole 31a of the outlet shield 31. It is introduced into 12b and moved to the outside of the epitaxial growth apparatus 1. As described above, the communication hole 30a of the exhaust shield 30 and the communication hole 31a of the outlet shield 31 and the gas flow are squeezed in two stages, thereby rectifying the gas flow and removing excess source gas from the gas flow. .

Here, the diffusion flux from the gas phase of the gas flow that determines the degree of growth of the epitaxial film to the wafer W surface is inversely proportional to the boundary layer thickness on the wafer W surface of the gas flow. By controlling the boundary layer thickness of the gas flow, it is possible to adjust the film thickness distribution of the epitaxial film at the position in the wafer plane direction.
Here, the boundary layer thickness is inversely correlated with the gas flow rate on the wafer W surface. If the gas flow rate is large, the boundary layer thickness decreases. Conversely, if the gas flow rate is small, the boundary layer thickness increases. Become.
Therefore, the boundary layer thickness can be controlled by arbitrarily adjusting the gas flow rate on the wafer W surface, and thereby the thickness distribution of the epitaxial film can be adjusted.

In the epitaxial growth apparatus 1 of the present embodiment, since the position H in the height direction of the plurality of gas supply holes 22 is individually set, the flow velocity of the gas flow supplied from each gas supply hole 22 on the wafer W surface. Can be set individually.
That is, of the gas supply holes 22 arranged along the curve C, if the gas supply hole 22 has a low height position H, it is closer to the surface of the wafer W. The flow velocity on the wafer W surface is large. On the other hand, if the gas supply hole 22 has a high height H, the gas supply hole 22 moves away from the surface of the wafer W. Therefore, the flow velocity of the gas flow through the gas supply hole 22 on the surface of the wafer W is small.

Thus, in the epitaxial growth apparatus 1 of the present embodiment, the gas flow velocity distribution on the wafer W surface can be set according to the height position H of each gas supply hole 22, so that the film is formed on the wafer W. It becomes possible to adjust the film thickness distribution of the epitaxial film.
Further, unlike the configuration in which the gas supply holes are opened and closed, the flow velocity of the gas flow supplied from the adjacent gas supply holes 22 is not greatly different, so that the reverse flow of the gas flow in the chamber 10 can be suppressed. Therefore, the gas flow does not transition to a turbulent flow, and a stable film thickness growth can be promoted while maintaining a laminar flow state.

  Furthermore, in this embodiment, the wafer W in each gas supply hole 22 is controlled so as to control the gas flow by compensating the film thickness distribution of the epitaxial film formed on the wafer W as the gas supply hole 22 having a uniform height. Since the position H in the height direction, which is the normal direction, is set along a curve C obtained by inverting the graph curve of the film thickness distribution of the basic example, the uniformity of the epitaxial film thickness of the wafer W is further improved. It becomes possible.

  Here, the gas flow supplied from the gas supply hole 22 does not immediately become a laminar flow state in the chamber 10, but moves after it is supplied into the chamber 10 and reaches the wafer W surface. Transition to the laminar flow state in the process. Therefore, it is necessary to ensure a certain distance between the gas supply hole 22 and the wafer W. On the other hand, when the distance between the gas supply hole 22 and the wafer W is too large, the flow rate of the gas flow is attenuated, so that a gas flow having an appropriate flow rate cannot be circulated on the wafer W.

  In this respect, in the present embodiment, since the horizontal distance L between the gas supply hole 22 and the wafer W is 10 cm or more, the gas flow is sufficiently laminar before reaching the wafer W surface. can do. In addition, since the distance L in the horizontal direction between the gas supply hole 22 and the wafer W is 50 cm or less, a gas flow having an appropriate flow rate can be circulated on the wafer W surface. As a result, a gas flow velocity distribution can be formed, and the epitaxial film thickness can be effectively uniformed.

  The epitaxial growth apparatus 1 according to the embodiment of the present invention has been described above. However, the present invention is not limited to this and can be appropriately changed without departing from the technical idea of the present invention.

  For example, in the embodiment, the gas supply hole 22 is substantially L-shaped and gas is supplied into the chamber 10 along the horizontal direction. However, as shown in FIG. It may be configured to be supplied inclined. Thereby, since the gas can be supplied toward the wafer W, the growth of the epitaxial film on the wafer W surface can be promoted as compared with the case where the gas is supplied in the horizontal direction.

  Further, the height position of the gas supply hole 22 may be variable. As an example of this, the gas rectifying member 40 shown in FIG. 8 may be used in place of the gas rectifying member 20 of the embodiment.

  In the gas rectifying member 40 of FIG. 8, a gas supply path 41 that extends vertically, a movable plate insertion hole 42, and a through hole 43 that faces the chamber 10 are formed in communication with each other in the order of gas passage. A movable plate 44 that closes the gas supply path 41 and the through hole 43 is provided in the movable plate insertion hole 42 so as to be movable up and down by an actuator (not shown). A gas supply hole 44 a that connects the gas supply path 41 and the through hole 43 in the horizontal direction is formed at a substantially central portion of the movable plate 44. A plurality of such gas supply holes 44a are provided in the same manner as the gas supply holes 22 of the embodiment.

  When the gas rectifying member 40 is employed, the height position of the gas supply hole 44 a for supplying gas into the chamber 10 can be arbitrarily changed by moving the movable plate 44 up and down. Therefore, since the height of each gas supply hole 44a can be arbitrarily changed according to the size and arrangement of the wafer W, the epitaxial film thickness can be made uniform corresponding to each wafer W. In this case, the gas ejection direction is parallel to the in-plane direction of the wafer W and parallel to each other.

  Further, the epitaxial film according to the basic example described above may be formed by making the height positions of the gas supply holes 44a of the gas rectifying member 40 uniform. Even in this case, the thickness of the epitaxial film is measured and graphed, and the height position of the gas supply hole 44a is changed along the curve C obtained by inverting the graph curve. Thereby, it is possible to compensate for the film thickness distribution and form an epitaxial film having a uniform film thickness distribution.

  Furthermore, the gas supply direction of the gas supply hole 22 may be variable. As an example of this, the gas rectifying member 40 shown in FIG. 9 may be used in place of the gas rectifying member 20 of the embodiment.

  In the gas rectifying member 50 of FIG. 9, a movable ball insertion portion 52 that faces the chamber 10 is formed at the lower end of the gas supply path 51 that extends downward. A movable sphere 53 that is rotated in the vertical direction by an actuator (not shown) or the like is inserted into the movable sphere insertion portion 52. The movable sphere 53 is formed with a gas supply hole 53a penetrating through two locations on the outer peripheral surface thereof in a substantially L shape. One opening of the gas supply hole 53a faces the chamber 10, and the other opening is The gas supply path 51 is connected to the lower end in a communicating state. The other opening of the gas supply hole 53a is formed wide so that the communication state between the gas supply hole 53a and the gas supply path 51 is maintained even when the movable ball 53 rotates. It has become.

  When such a gas rectifying member 50 is employed, the direction of one opening of the gas supply hole 53 a for supplying gas into the chamber 10 can be changed by the rotation of the movable sphere 53. Therefore, fine adjustment of the speed of the gas flow supplied onto the wafer W surface can be achieved, and the epitaxial film thickness uniformity of the wafer W can be further improved. In this case, the movable ball insertion part 52 can be rotated only with respect to the rotation axis that is perpendicular to the gas flow, and the ejection direction only in the height direction can be changed.

  In the epitaxial growth apparatus 1 described above, the case where a single wafer W is placed on the susceptor 13 has been described. However, the present invention is not limited to this, and a plurality of wafers W are placed on the susceptor 13. It may be what was done. Even in this case, as described in the embodiment, by setting the height of the gas supply hole 22 individually, in-plane uniformity of film characteristics such as the film formation state of the epitaxial film can be achieved. .

An epitaxial film was actually grown by the epitaxial growth apparatus 1 of the embodiment.
As shown in FIG. 5, the case where all the gas supply holes 22 have the same height position is used as a basic example, and as shown in FIG. 6, the case where the height positions of the gas supply holes 22 are individually set is used as an example. .
In the embodiment, the height setting of the gas supply hole 22 is changed based on the result of the basic example.
These results are shown in FIG.

As a result, implemented in the height H ₀ is equal to the basic example of the gas supply holes 22 ', a large unevenness in the wafer W surface has occurred, and the height position H of the gas supply holes 22 are individually set example The film thickness uniformity was improved.

DESCRIPTION OF SYMBOLS 1 Epitaxial growth apparatus 2 Gas flow path 10 Chamber 10a Top surface 10b Bottom face 13 Susceptor 20 Gas rectification member 21 Wafer conveyance hole 21a Closure member 22 Gas supply hole 22 'Gas supply hole 40 Gas rectification member 41 Gas supply path 42 Movable plate insertion hole 43 Through hole 44 Movable plate 44a Gas supply hole 50 Gas rectifying member 51 Gas supply path 52 Movable sphere insertion part 53 Movable sphere
53a Gas supply hole

Claims (6)

A chamber in which a gas flow path is provided and a susceptor for holding a wafer is provided in the gas flow path;
In an epitaxial growth apparatus provided with a gas supply hole that is arranged on the upstream side of the gas flow path and a plurality of gas supply holes are arranged in parallel in a direction crossing the gas flow path
The epitaxial growth apparatus characterized in that the position of the gas supply hole in the height direction, which is the normal direction of the wafer, is set individually for each of the gas supply holes. The position in the height direction that is the wafer normal direction of the gas supply hole,
The gas supply hole having a uniform height is set corresponding to the film thickness distribution of the epitaxial film so as to control the gas flow by compensating the film thickness distribution of the epitaxial film formed on the wafer. The epitaxial growth apparatus according to claim 1, wherein   The epitaxial growth apparatus according to claim 1 or 2, wherein the position of the gas supply hole in the height direction, which is the normal direction of the wafer, is individually variable.   4. The epitaxial growth apparatus according to claim 1, wherein a gas flow supply direction of the gas supply holes is individually variable along a wafer normal direction. 5.   5. The horizontal distance between the gas supply hole and the wafer along the wafer surface is set in a range of 10 cm to 50 cm. 5. The epitaxial growth apparatus described. A method for producing a silicon epitaxial wafer by the apparatus according to claim 1,
The boundary layer thickness in the gas flow in the wafer in-plane direction perpendicular to the gas flow channel in the gas flow channel for flowing the film forming gas is set to a height position in the wafer normal direction of the gas supply hole, or the gas A method for producing a silicon epitaxial wafer, wherein the thickness distribution in the wafer surface of the epitaxial film is controllable by setting the height direction of the gas ejection direction from the supply hole.

Images