JP2009071210A - Susceptor and epitaxial growth system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a susceptor to be used for an epitaxial growth system which has a mechanism that heats up the wafer from the top face by the reflection of heat and from the bottom face by high-frequency induction, while reducing the occurrence of defects caused by anchoring of a wafer with the side face of a spot facing of the susceptor, and to provide the epitaxial growth system. <P>SOLUTION: In the top face of the susceptor 14, a spot facing wherein a wafer 16 is to be disposed is formed, a portion 32 of the side face of the spot facing which is located above the horizontal center plane 30 of the wafer 16 to be disposed in the spot facing is set as an inclined surface which gradually becomes wider, as going upward. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a susceptor and a vapor phase growth apparatus used in a vapor phase growth apparatus, and more particularly to a susceptor and an epitaxial growth apparatus used in an epitaxial growth apparatus.

  In manufacturing processes of various semiconductor devices such as bipolar, CMOS, and discrete, an epitaxial growth apparatus that grows a single crystal semiconductor layer on a semiconductor substrate to be processed is used.

  The epitaxial growth apparatus includes apparatuses such as a cylinder apparatus (so-called barrel type apparatus), a vertical apparatus (so-called pancake type apparatus), and a sheet-like apparatus.

  The cylinder device has a truncated pyramidal susceptor in a cylindrical quartz bell jar. A plurality of wafers are arranged on the susceptor in a state close to vertical. The reaction gas is supplied from the upper part of the quartz bell jar, circulates in the quartz bell jar, and is discharged from the lower part of the quartz bell jar. Further, the wafer is heated from the outside of the quartz bell jar by lamp heating or high frequency induction heating. The truncated pyramidal susceptor rotates around its own axis to equalize the heating of the wafer and the supply of reactant gas to the wafer.

  Since the cylinder device can process a large number of wafers at a time, it has an advantage of excellent mass productivity. However, due to the configuration in which multiple wafers are placed on the susceptor and the reaction gas flows from the upper side to the lower side of the susceptor, the uniformity of the semiconductor single crystal layer within the wafer surface or between the wafers, especially when the wafer diameter increases There is a problem that it is damaged.

  The vertical apparatus has a rotating disk-shaped susceptor in a hemispherical quartz bell jar having a large volume. A plurality of wafers are horizontally arranged on the susceptor. The reaction gas is supplied perpendicularly to the wafer from above and circulates in the quartz bell jar. Further, the wafer is heated by high-frequency induction heating using a coil provided inside the quartz bell jar. By rotating the disk-shaped susceptor, the heating of the wafer and the supply of the reaction gas to the wafer are made uniform.

  The vertical apparatus, like the cylinder apparatus, can process a large number of wafers at a time, and thus has an advantage of excellent mass productivity. In addition, the uniformity of the semiconductor single crystal layer within the wafer surface is improved as compared with the cylinder device because of the configuration in which the reaction gas is supplied vertically from above with respect to the wafer. However, because of the device configuration, it is necessary to provide a coil for induction heating in the quartz bell jar, which may cause wafer contamination due to the coil. In addition, since heating is performed only from the lower side of the wafer, the temperature gradient between the lower surface and the upper surface of the wafer becomes large, and there is a problem that the wafer may be damaged such as slip or crack due to thermal stress.

  The single wafer type apparatus is characterized by processing wafers one by one unlike the cylinder apparatus and the vertical apparatus. In this apparatus, only one wafer is placed on a susceptor in a relatively small quartz chamber. The reaction gas is supplied from one direction of the quartz chamber, flows as a laminar flow on the wafer, and is exhausted in the other direction. The wafer is heated from both the upper and lower surfaces by halogen lamps provided above and below the quartz chamber.

  The single wafer processing system processes wafers one by one in a small chamber, so that even when the wafer diameter is increased compared to a cylinder device or a vertical device, a uniform semiconductor single crystal layer is formed. Improves. In addition, since the wafer is heated from both sides, the temperature gradient between the upper and lower surfaces of the wafer can be reduced, and damage to the wafer due to thermal stress can be reduced. However, throughput can be reduced because only one wafer can be processed at a time. For this reason, there has been a problem that productivity is lowered particularly when a thick semiconductor single crystal layer is deposited.

  Thus, an epitaxial growth apparatus that improves the productivity while preserving the advantage that the uniformity of the semiconductor single crystal layer is good has been proposed (Patent Documents 1 and 2).

  In this apparatus, a disk-shaped susceptor is provided in a quartz chamber whose upper and lower surfaces are substantially parallel. The susceptor is provided with a plurality of circular counterbore for arranging the wafers in order to process a plurality of wafers simultaneously. The reaction gas is supplied from one direction of the quartz chamber as in the case of the single wafer apparatus, flows as a laminar flow on the wafer, and is exhausted in the other direction. Further, the wafer to be processed is heated from the lower surface of the wafer by induction heating of the susceptor by a coil provided outside the quartz chamber, and at the same time, is heated from the upper surface of the wafer by reflection of heat from the upper portion of the quartz chamber.

According to the devices of Patent Documents 1 and 2, the flow of the reaction gas can be controlled as a laminar flow like a single wafer device, so that the uniformity of the semiconductor single crystal layer can be improved. In addition, since a plurality of wafers can be processed simultaneously, throughput is increased and productivity is improved. Moreover, since the temperature gradient in the wafer can be kept small by heating both surfaces of the wafer at the same time, the wafer is hardly damaged by thermal stress. Further, since the coil for induction heating is installed outside the chamber, wafer contamination caused by the coil can be avoided.
Japanese National Patent Publication No. 9-505798 JP-T-2005-505134

  However, in the devices of Patent Documents 1 and 2, the semiconductor film grown near the bevel of the wafer may adhere to the side face of the counterbore of the susceptor, and damage such as cracks may occur in the wafer. FIG. 5 is an enlarged cross-sectional view of a counterbore end of a susceptor of a prior art device. With reference to FIG. 5, the phenomenon that the bevel surface and the side face of the counterbore of the susceptor stick together in this prior art apparatus will be described. FIG. 5A is a cross-sectional view before the semiconductor single crystal layer is formed, and FIG. 5B is a cross-sectional view after the semiconductor single crystal layer is formed.

  As shown in FIG. 5, the wafer 16 to be processed is disposed on the counterbore of the susceptor 14. In particular, as shown in FIG. 5A, the side surfaces of the counterbore of the wafer and the susceptor are in contact with each other or close to each other. Think about the case. As shown in FIG. 5B, when the semiconductor single crystal layer 36 is deposited on the wafer 16, the semiconductor film is also deposited on the bevel surface 38, and the film grows in the lateral direction. For this reason, the side face of the counterbore of the wafer and the susceptor is fixed by the grown film, and stress is applied to this part, thereby causing damage such as slip and crack.

  FIG. 6 is an enlarged cross-sectional view of a counterbore end portion of the susceptor in the vertical apparatus. 6A is a cross-sectional view before the semiconductor single crystal layer is formed, and FIG. 6B is a cross-sectional view after the semiconductor single crystal layer is formed. Even if the counterbore shape of the susceptor is the same as that of FIG. 5, in the case of the vertical apparatus, a temperature gradient is generated in the wafer so that the lower surface becomes high temperature. Therefore, as shown in FIG. 6B, the thermal expansion causes warping so that the wafer becomes concave upward. For this reason, since the distance between the upper surface of the bevel and the side surface of the counterbore is relatively increased, the above-described sticking hardly occurs.

  As described above, in the apparatus of Patent Documents 1 and 2, since the temperature gradient in the wafer is reduced as compared with the case of the vertical apparatus or the like, there is a defect due to adhesion between the wafer and the side face of the counterbore of the susceptor. The problem of being easy to occur has arisen.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a susceptor and an epitaxial growth apparatus used in an epitaxial growth apparatus that reduce the occurrence of defects due to adhesion between the wafer and the side face of the counterbore of the susceptor. There is to do.

  A susceptor of one embodiment of the present invention is a susceptor used in an epitaxial growth apparatus that heats a semiconductor substrate to be processed from the upper surface by reflection of heat and high-frequency induction from the lower surface, and the semiconductor substrate to be processed is disposed on the upper surface of the susceptor. A counterbore is formed, and a portion of the side face of the counterbore corresponding to the upper part of the horizontal center plane of the substrate to be processed is an inclined surface that extends upward.

  Here, it is desirable that an angle of the inclined surface with respect to a horizontal plane is 45 degrees or more and 80 degrees or less.

  Here, it is desirable that the semiconductor substrate to be processed is heated from the upper surface by reflection of heat by a metal film provided on the upper part of the processing chamber of the epitaxial growth apparatus.

  An epitaxial growth apparatus of one embodiment of the present invention includes the susceptor of one embodiment of the present invention described above, and has a mechanism for heating a semiconductor substrate to be processed by heat reflection from the upper surface and high-frequency induction from the lower surface.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the susceptor and epitaxial growth apparatus which are used for an epitaxial growth apparatus which reduce the generation | occurrence | production of the defect by adhesion with a wafer and the side face of the counterbore of a susceptor.

  Embodiments of a susceptor and an epitaxial growth apparatus according to the present invention will be described below with reference to the accompanying drawings.

  The susceptor according to the embodiment of the present invention is a susceptor used in an epitaxial growth apparatus having a mechanism for heating a semiconductor substrate to be processed from the upper surface by heat reflection and high-frequency induction from the lower surface. A counterbore in which the semiconductor substrate to be processed is disposed is formed on the upper surface of the susceptor. And the part corresponding to the upper part from the horizontal center plane of the to-be-processed substrate arrange | positioned is the inclined surface which spreads upwards.

  The epitaxial growth apparatus of the present embodiment is an epitaxial growth apparatus having the above-described susceptor, and having a mechanism for heating the semiconductor substrate to be processed by heat reflection from the upper surface and high-frequency induction from the lower surface.

  FIG. 2 is a diagram showing a main part of the epitaxial growth apparatus according to the embodiment of the present invention. 2A is a cross-sectional view of the epitaxial apparatus, and FIG. 2B is a top view of the susceptor.

  As shown in FIG. 2A, the epitaxial growth apparatus 10 according to the present embodiment includes a reaction chamber 12 made of an insulating material that is inert and transparent to a reaction gas and a reaction product, for example, quartz. The reaction chamber 12 has a substantially rectangular cross-sectional shape and includes a disk-shaped susceptor 14 inside.

  As shown in FIG. 2B, the susceptor 14 has a slightly larger diameter than the wafer diameter in order to fix and arrange a plurality of wafers 16a and 16b (FIG. 2A) which are semiconductor substrates to be processed. Circular counterbore 18a, 18b, 18c, 18d, that is, a recess is provided. Here, although four wafers are arranged on the susceptor 14, the number of wafers is not necessarily limited to four.

  The susceptor 14 is connected to a rotating shaft 26 and is configured to rotate by a motor (not shown). This rotation makes the reaction between the respective wafers uniform and improves the uniformity of the semiconductor single crystal layer between the wafers.

  The reaction chamber 12 includes a gas supply port 20 for introducing a reaction gas, and a gas discharge port 22 for discharging a residual gas of the reaction gas and a reaction product gas on the opposite side of the susceptor 14 of the gas supply port 20. It has. As described above, the reaction gas introduced from the gas supply port 20 flows as a laminar flow on the wafers 16a and 16b as indicated by arrows, reacts on the wafer, and deposits a semiconductor single crystal layer, for example, a silicon layer, The gas is exhausted from the gas outlet 22.

  As shown in FIG. 2A, a coil 24 is provided outside the reaction chamber to perform high-frequency induction heating. A high frequency current is supplied to the coil 24 from an external generator (not shown). For example, the susceptor 14 made of a carbon material coated with silicon nitride (SiC) is heated by an induced current generated in the susceptor 14 by a high-frequency current flowing through the coil 24. Then, the wafers 18a to 18d are heated from the lower surface of the wafer by heat conduction from the susceptor 14 heated by the induced current.

  A metal coating 28 is formed on the outer wall side of the upper surface of the reaction chamber 12. For example, the metal coating 28 is gold plating. By providing the metal coating 28 on the upper surface of the reaction chamber 12 in this manner, the radiant heat from the susceptor 14 and the wafers 16a and 16b is reflected. The wafers 16a and 16b are also heated from the upper surface of the wafer by this reflected heat.

  As described above, the wafer is heated by reflection of heat from the upper surface and high-frequency induction from the lower surface, thereby eliminating the temperature gradient between the upper surface and the lower surface of the wafer and preventing the occurrence of slip or the like due to thermal stress.

  Note that the method of heating the wafer by reflection of heat from the upper surface of the wafer is preferably based on a metal coating because the reflection efficiency is high. However, it is not always necessary to use a metal coating, but for example, an opaque ceramic plate or the like may be provided on the upper surface of the reaction chamber, and heat may be reflected by this ceramic plate. In the present specification, for example, when a ceramic plate once absorbs heat and then generates radiant heat, it is regarded as reflection in a broad sense.

  FIG. 1 is an enlarged cross-sectional view of a counterbore end portion of the susceptor of the present embodiment used in the above-described epitaxial apparatus. FIG. 1A is a cross-sectional view before the semiconductor single crystal layer is formed, and FIG. 1B is a cross-sectional view after the semiconductor single crystal layer is formed.

  As shown in FIG. 1A, a portion 32 of the side face of the counterbore of the susceptor 14 corresponding to the upper part of the horizontal center plane 30 of the wafer 16 to be processed is an inclined surface that extends upward. is there. This inclined surface has an angle θ with respect to the horizontal plane. Here, the reason why one step is provided between the surface of the susceptor 14 and the inclined surface is to facilitate the holding of the wafer by the transfer robot, and the structure essential to the present invention is not necessarily required. Absent.

  In this way, by providing the side face of the counterbore with an inclination, unlike the prior art shown in FIG. 5, as shown in FIG. 1A, the bevel surface 38 of the wafer 16, the side face of the counterbore, Can be substantially separated. Therefore, as shown in FIG. 1B, when the semiconductor single crystal layer 36 is deposited on the wafer 16, even if the semiconductor film is deposited on the bevel surface 38 and the semiconductor film grows in the lateral direction, The side surface of the counterbore of the susceptor is less likely to stick. Therefore, it is possible to reduce the occurrence of defects due to adhesion between the wafer and the side face of the counterbore of the susceptor.

  In the present embodiment, the portion 32 corresponding to the upper part of the horizontal center surface 30 of the wafer 16 is particularly inclined because the bevel surface on the upper surface of the wafer and the side surface of the counterbore are particularly problematic. is there. This is because, by providing an oxide film or the like on the bevel surface on the lower surface of the wafer, the growth of the semiconductor single crystal layer is suppressed in the first place, or the end of the wafer is in contact with or close to the side surface of the counterbore. This is because film growth on the bevel surface on the lower surface of the substrate is suppressed.

  It is also conceivable to prevent sticking by making the height of the side face of the counterbore itself lower than the center plane of the wafer. However, if the height of the side surface is made lower than that of the wafer, there may be a problem of non-uniformity of the film within the wafer surface due to disturbance of the flow of the reaction gas. Further, if the side surface is too shallow, it is not desirable because the wafer is likely to be displaced from the spot facing when the wafer is placed on the susceptor by the transfer robot or during the film forming process.

  Here, it is desirable that the angle θ of the inclined surface with respect to the horizontal plane is 45 degrees or more and 80 degrees or less. Below this range, there is a greater risk that the wafer will slip off the spot. Further, if it exceeds this range, a sufficient distance between the bevel surface and the side face of the spot facing cannot be secured, and the risk of wafer sticking increases.

  If the growth rate of the semiconductor single crystal film is increased in order to improve productivity, the bevel surface growth rate may be higher than the wafer surface depending on the plane orientation of the wafer. This embodiment is particularly effective when the semiconductor single crystal layer is grown under such conditions.

  Further, the shape of the side face of the counterbore is not necessarily limited to the shape as shown in FIG. 1, for example, without providing one step from the surface of the susceptor as shown as a modification in FIG. 3. An inclined surface may be provided.

  Further, for example, as shown as a modification in FIG. 4, an inclined surface may be provided up to a portion corresponding to the lower part of the horizontal center surface 30 of the wafer 16.

  The embodiments of the present invention have been described above with reference to specific examples. In the description of the embodiment, the description of the susceptor and the epitaxial growth apparatus used in the epitaxial growth apparatus, which are not directly required for the description of the present invention, is omitted, but the susceptor used in the required epitaxial growth apparatus and Elements related to the epitaxial growth apparatus and the like can be appropriately selected and used.

  In addition, a susceptor and an epitaxial growth apparatus used for all epitaxial growth apparatuses that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

It is an expanded sectional view of the counterbore edge part of the susceptor of an embodiment. It is a figure which shows the principal part of the epitaxial growth apparatus of embodiment. It is an expanded sectional view of the counterbore edge part of the susceptor of the modification of embodiment. It is an expanded sectional view of the counterbore edge part of the susceptor of the modification of embodiment. It is an expanded sectional view of the counterbore edge part of a susceptor of a prior art. It is an expanded sectional view of the counterbore edge part of a susceptor of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Epitaxial growth apparatus 12 Reaction chamber 14 Susceptor 16 Wafer 18a, b, c, d Counterbore 24 Coil 28 Metal coating 30 Horizontal center plane 38 Bevel surface

Claims (4)

A susceptor used in an epitaxial growth apparatus having a mechanism for heating a semiconductor substrate to be processed from the upper surface by reflection of heat and high-frequency induction from the lower surface,
On the upper surface of the susceptor, a counterbore in which the semiconductor substrate to be processed is arranged is formed,
The susceptor characterized in that a portion of the side face of the counterbore corresponding to an upper part of a horizontal center plane of the substrate to be processed is an inclined surface that extends upward.   The susceptor according to claim 1, wherein an angle of the inclined surface with respect to a horizontal plane is not less than 45 degrees and not more than 80 degrees.   The susceptor according to claim 1, wherein the semiconductor substrate to be processed is heated from above by reflection of heat by a metal film provided on an upper portion of a processing chamber of the epitaxial growth apparatus. An epitaxial growth apparatus comprising the susceptor according to claim 1 and having a mechanism for heating the semiconductor substrate to be processed by heat reflection from the upper surface and high-frequency induction from the lower surface.

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