JP4855029B2 - Semiconductor crystal growth equipment - Google Patents

Description

  The present invention relates to an apparatus for growing a semiconductor crystal such as silicon carbide.

  Silicon carbide (SiC) is a semiconductor that has a breakdown electric field strength of about 10 times that of silicon (Si), and also has excellent physical properties in terms of thermal conductivity, electron mobility, band gap, and the like. Therefore, it is expected as a semiconductor material that realizes a dramatic performance improvement as compared with conventional silicon-based power semiconductor elements.

  As a conventional growth apparatus for crystal growth of silicon carbide for semiconductors, for example, a so-called horizontal crystal growth apparatus 100 shown in FIG. 3, a cylindrical substrate support (hereinafter referred to as a susceptor) that supports a single crystal substrate 101 is used. ) 102 is installed in the same direction as the supply pipe 104. A single crystal substrate 101 is placed on the bottom surface 102 b of the inner peripheral portion of the susceptor 102, and an induction coil 105 for induction heating the susceptor 102 is installed around the supply pipe 104.

  Then, by induction heating the susceptor 102 by the induction coil 105 to heat the single crystal substrate 101 to about 1500 ° C. and supplying the reaction gas 103 in the direction of the arrow, the component elements of the reaction gas 103 are formed on the surface of the single crystal substrate 101 Alternatively, the compound is continuously deposited and grown to form a single crystal thin film.

  By the way, in such a crystal growth apparatus 100, since the susceptor 102 is cylindrical and arranged in parallel with the flow direction of the reaction gas 103, when the susceptor 102 is induction-heated, the susceptor 102 becomes the highest temperature. Then, the surface of the susceptor 102 may be etched by the reaction gas 103 or the carrier gas at the high temperature. Such etching of the susceptor surface causes impurities to be released from the susceptor and lowers the purity of the formed single crystal film. Further, the etching action on the surface of the susceptor 102 becomes more prominent as the temperature of the susceptor 102 becomes higher. In particular, a thick silicon carbide single crystal that requires a high temperature (1500 ° C. or higher) and a long-time reaction is required. There was a problem of inhibiting the growth of the film.

  On the other hand, since single crystal substrate 101 is heated by heat transfer from high-temperature susceptor 102, the temperature difference between single crystal substrate 101 and susceptor 102 tends to increase as the temperature rises. This temperature difference between the single crystal substrate 101 and the susceptor 102 has a problem of shortening the life of the coating film of the susceptor 102.

  Further, in such a horizontal crystal growth apparatus 100, there is a limit to the number of substrates that can be processed at one time. To increase the number of processed substrates or increase the diameter of the substrate, the entire apparatus must be enlarged. There was a problem of not becoming. However, when the size of the apparatus is increased, it is difficult to ensure the uniformity of the flow rate of the reaction gas 103, and there arises a problem that the resulting crystals vary.

Thus, there is also provided a gas supply pipe arranged vertically as shown in FIG. 4 so that a large amount of substrates can be processed at one time (Patent Document 2).
In this semiconductor crystal growth apparatus 10, the supply pipe 11 is arranged vertically, and an induction heating apparatus 26 is arranged on the outer periphery thereof. The substrate holding jig 30 is accommodated in the inner chamber 12 defined by the first partition wall 18 and the second partition wall 22 so as to have a rectangular cross section, and the substrate 32 is provided at each stage of the substrate holding jig 30. Has been placed.

A so-called pancake type vapor phase growth apparatus is also known (Patent Documents 3 and 4).
In these pancake-type growth apparatuses, a susceptor is arranged in a dome-shaped space called a “pergia”.
JP 2001-122692 A Japanese Patent Laid-Open No. 9-330884 JP 2000-175959 A JP 7-45530 A

  By the way, in the growth apparatus 10 of Patent Document 2, since the reaction gas is introduced from the lower side of the apparatus main body and the reaction gas is discharged from the same direction, a difference occurs in the flow velocity and flow rate of the gas in the inner chamber 12. There was a problem that the thickness of the crystal was varied.

  In addition, in the growth apparatus 10 of Patent Document 2, since introduction and discharge of gas are performed using a nozzle or the like, there are problems that the number of parts increases and the structure becomes complicated.

  Moreover, in the conventional growth apparatuses 10 and 100, the heat insulation of the supply pipes 11 and 104 is not sufficient, and the heat retention of the reaction chamber is impaired, so that it is difficult to maintain the homogeneity of the temperature distribution in the reaction chamber (especially like SiC). When high temperature heating is required). As a result, there is a problem that the quality of the obtained crystal varies. Furthermore, there is a problem that it takes extra time and energy to raise the temperature once lowered.

  In addition, the pancake molds of Patent Document 3 and Patent Document 4 have a limited number of substrates that can be processed at one time as compared with the growth apparatus 100 shown in FIG. In particular, there is a problem in that the lateral enlargement is required and the uniformity of the quality of the crystal film is impaired.

  In view of such circumstances, the present invention can simultaneously process a large number of large-diameter substrates, has a simple structure, sufficient heat insulation in the reaction chamber, and sufficient temperature distribution homogeneity, thereby shortening the processing time. It is an object of the present invention to provide a semiconductor crystal growth apparatus that can be made uniform, and that the purity of the crystal film is good, and variations in the obtained crystal can be minimized.

In order to achieve the above object, a semiconductor crystal growth apparatus according to the present invention comprises:
A gas supply pipe which is arranged in a vertical shape and into which a reaction gas is introduced in a limited space;
Induction heating means disposed on the outer peripheral surface of the gas supply pipe;
A radiating member having a bottomed cylindrical structure that is disposed on the inner peripheral side of the gas supply pipe so as to face the induction heating means, and a gas introduction port and a gas discharge port are respectively formed on opposite side wall surfaces;
A susceptor constituting member that is integrally supported by a shaft inserted inward of the radiation member and configured in a shelf shape so that a plurality of substrates can be placed in a substantially horizontal direction;
Power means for applying a rotational force and a moving force in a linear direction to a shaft that supports the susceptor component,
An inner heat insulating material is interposed between the gas supply pipe and the radiation member,
On the upper part of the radiating member, an upper heat insulating material is installed immovably,
Between the susceptor constituent member and the shaft, a lower heat insulating member in which a plurality of reflectors are placed in multiple stages is installed, and the susceptor constituent member is supported by the shaft via the lower heat insulating member,
The reaction gas is introduced from the upper part in the axial direction , passes through the outside of the radiation member, travels downward in the axial direction , and then is supplied in a substantially horizontal direction from the gas inlet toward the inside of the susceptor component, Fed from the gas outlet through the outside of the inner cylinder to the lower part in the axial direction, or
The reaction gas is introduced from the lower part in the axial direction, passes through the outside of the radiating member, travels upward in the axial direction, and then is supplied in a substantially horizontal direction from the gas inlet toward the inside of the susceptor component, The gas discharge port is fed to the upper part in the axial direction through the outside of the inner cylinder .

  According to the present invention having such a configuration, since the radiating member heated by induction heating has a bottomed cylindrical structure, the outside of the radiating member can be configured as a gas passage. Therefore, a member such as a nozzle is not necessary for introducing gas, and the number of parts can be reduced.

Furthermore, since the susceptor constituting member is formed in a shelf shape and can be arranged so as to spread almost entirely inside the gas supply pipe, a large-diameter substrate can be processed without making the entire apparatus so large. Can do.
In the present invention, a lower heat insulating member is installed between the susceptor constituent member and the shaft, and the susceptor constituent member is supported by the shaft through the lower heat insulating member. It is compact and can improve the heat insulation of the lower part of the heel.

  Further, the reaction gas passes through the outside of the radiating member and advances in the axial direction, and then is supplied in a substantially horizontal direction from the gas inlet toward the inside of the susceptor component, and then radiates from the gas outlet. Since it is fed in the axial direction through the outside of the member, it can contribute to the homogenization of crystals.

Moreover, in this invention, since the inner side heat insulating material is interposed between the said gas supply pipe | tube and the said radiation member, the heat insulation in an outer peripheral part can be improved.
Furthermore, since the upper heat insulating material is immovably installed on the upper portion of the radiating member, the heat insulating property on the upper portion of the radiating member can be improved.

Furthermore, in the present invention, between the shaft and the susceptor component is lower heat insulator is installed, since the susceptor component through the lower heat insulator is supported by the shaft, the entire device The heat insulating property of the lower part can be improved while being compact.

Moreover, in this invention, since the said lower heat insulator is a thing in which the several reflecting plate was mounted in multistage, it can reflect radiant heat with a reflecting plate.
Furthermore, since the plurality of reflecting plates are simply placed in multiple stages, the reflecting plates can be easily installed and the heat insulating property is exhibited extremely well. Thereby, homogenization of the temperature distribution of the reaction chamber can be achieved. Moreover, the heat insulation effect can be easily adjusted by changing the number of reflectors.

Furthermore, in the present invention, it is preferable that a decompression means is connected to the gas supply pipe.
With such a configuration, impurities are not mixed in the crystal growth, and a more uniform crystal film can be grown.

Moreover, it is preferable that the said reactive gas is introduce | transduced from either one of the axial direction upper part or the lower part, and is discharged | emitted from either one.
With such a configuration, the difference in the flow rate and flow rate of the reaction gas is reduced.

According to the semiconductor crystal growth apparatus of the present invention, since the reaction gas can be flowed using the outside of the radiation member, a member for introducing a gas such as a nozzle is unnecessary, and the structure is compact. In addition, a large number of large substrates can be processed simultaneously. Furthermore, since the space where the reaction is performed is covered with a heat insulating material, the heat retention effect is high, and heat energy can be used effectively. Moreover, since the downward heat insulation member is easy to adjust the heat insulation property, it can provide preferable heat insulation properties.

  In addition, the flow rate of the reaction gas can be kept substantially constant between the upper part and the lower part, and the susceptor constituting member can be rotated, so that the uniformity of crystals can be improved.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a part of a semiconductor crystal growth apparatus according to an embodiment of the present invention. In the present specification, “upper”, “lower”, “right”, “left” and the like are used for convenience of explanation, and “upper” means “right” on the paper surface in FIG. 1 shows the right side of the page in FIG. 1, but it can also be arranged upside down, left and right.

  That is, the crystal growth apparatus 50 includes a substantially cylindrical gas supply pipe 52, an induction heating means 54 disposed on the outer peripheral surface of the gas supply pipe 52, and the gas supply pipe 52 so as to face the induction heating means. A bottomed cylindrical radiating member 56 disposed on the inner peripheral surface, a shaft 59 inserted inside the radiating member 56, and a shelf supported by the shaft 59 so that a plurality of substrates can be placed in a substantially horizontal direction. A susceptor constituting member 58 configured in a shape, and power means 60 for applying a rotational force and a linear moving force to the shaft 59.

  Further, in the present embodiment, the inner heat insulating material 62 is provided between the substantially cylindrical gas supply pipe 52 and the radiation member 56, the upper heat insulating material 64 is provided on the upper portion of the radiation member 56, and the susceptor constituting member 58 and the shaft 59. A lower heat insulating member 66 is installed between them.

  The gas supply pipe 52 is specifically formed of a quartz pipe so as not to be induction-heated and is arranged in a vertical shape. However, the upper and lower end surfaces outside the figure are sealed, so that a space S limited to the inside is formed. It is composed.

More specifically, the induction heating means 54 is an induction coil that generates a magnetic field by an alternating current.
The radiation member 56 is induction-heated by the outer induction heating means 54, and is made of, for example, a conductive material whose surface is covered with silicon carbide. The radiation member 56 of the present embodiment has a bottomed double cylinder structure, and is disposed so that the vertically inverted position, that is, the bottom portion forms the ceiling surface 72. Thus, in the present embodiment, since the radiation member 56 is formed in a double cylindrical shape, it is promoted to heat the space S substantially uniformly. The radiating member 56 may be a simple cylindrical body, and is not limited to a double-structured cylindrical body.

  The ceiling surface 72 is made of a graphite material, and connects the annular inner cylinder 68 and the annular outer cylinder 70 to each other to substantially close the top plate surface. Is formed with an opening 72a, and the opening 72a communicates with the internal space S. As a result, the reaction gas supplied from the opening 72a on the left side of the figure is guided in the vertical direction through the gap between the double cylinders 68 and 70 as indicated by the arrows in the figure. On the other hand, the right outer peripheral region of the ceiling surface 72 in FIG. 1 is closed by a ceiling plate portion 72 b that constitutes a part of the ceiling surface 72.

  Further, a gas introduction port 74 for changing the flow direction of the reaction gas flowing from above is formed in the inner cylinder 68 at a substantially intermediate position in the height direction of the radiation member 56, and the inner cylinder 68 on the opposite side is formed in the inner cylinder 68. Is formed with a gas discharge port 76. The gas inlet port 74 and the gas outlet port 76 are formed in a substantially rectangular shape when viewed from the left side of the figure and the right side of the figure, but the gas inlet port 74 and the gas outlet port 76 are formed. The shape is not limited to this. For example, even if it is not a large rectangular shape like a window, a large number of small holes are provided in a row within the same window frame, and the gas introduction hole 74 and the gas discharge port 76 are configured by these small holes. Anyway.

In the vicinity of the lower part of the gas introduction port 74, the gap between the inner cylinder 68 and the outer cylinder 70 is substantially closed by a flange 78. Thus, the reaction gas flowing downward from above does not inadvertently flow downward beyond the flange 78, and most of the reaction gas is led out in the horizontal direction. On the other hand, in the vicinity of the outlet on the gas outlet 76 side, openings 78a and 78b are formed in the flange 78 so that the reactive gas can be positively discharged downward.

  Therefore, by forming such a gas inlet 74 and gas outlet 76 in the radiating member 56, the reaction gas supplied into the gas supply pipe 52 is supplied from above as indicated by arrows in the figure. It flows downward, further in the horizontal direction, and then flows downward.

  The shaft 59 can apply a rotational force and a linear moving force in the axial direction to the susceptor constituting member 58 by the force from the power means 60. Therefore, during actual driving, if a rotational force is applied to the shaft 59 by the power means 60, the substrate in the susceptor constituting member 58 rotates, so that uniform crystal growth can be promoted.

  Further, in the growth apparatus 50 of the present embodiment, a lower heat insulating member 66 composed of a large number of reflecting plates 66 a is installed at the tip of the shaft 59, and the susceptor constituting member 58 is integrated with the shaft 59 through the lower heat insulating member 66. Is installed.

  The susceptor constituting member 58 is configured in a shelf shape so that a disk-shaped substrate (not shown) can be placed or fixed to the back surface using a stopper or the like. In the embodiment, eight shelf plates 58a, 58a, 58a... The shelf plates 58a and 58a are integrated by being positioned at predetermined intervals by a plurality of pin members or the like. Further, the lowermost shelf plate 58a 'is integrated with the uppermost reflection plate 66a'.

  Therefore, in this embodiment, if the shaft 59 moves linearly by the force from the power means 60, for example, the susceptor constituting member 58 also moves linearly together with the lower heat insulating member 66 made of the reflecting plate 66a, and if the shaft 59 rotates, the susceptor. The component member 58 also rotates together with the lower heat insulating member 66.

  The lower heat insulating member 66 improves the heat insulating property of the space S and the homogeneity of the temperature distribution. Specifically, a plurality of substantially tray-shaped (bottom-bottomed cylindrical) reflectors 66a are stacked in the vertical direction. Therefore, the air layer a inside the lower heat insulating member 66 is not hermetically sealed, and the inside of the air layer a during operation of the furnace is maintained in a reduced pressure atmosphere or a state close to vacuum.

According to such a lower heat insulating member 66, the heat insulating performance can be easily adjusted by appropriately increasing or decreasing the number of reflection plates 66a to be laminated.
On the other hand, the upper heat insulating material 64 disposed above the ceiling surface 72 of the radiating member 56 is made of carbon fiber or the like, and is fixedly provided on the ceiling surface 72 of the radiating member 56.

The inner heat insulating material 62 disposed on the inner peripheral surface of the gas supply pipe 52 is made of carbon fiber or glass wool, and insulates the outer peripheral side of the radiating member 56.
Thus, in the crystal growth apparatus 50 according to the present embodiment, the upper part is insulated by the upper heat insulating material 64, the outer peripheral surface is insulated by the inner heat insulating material 62, and the lower side is insulated by the lower heat insulating member 66. Is very good in heat retention.

Further, in the present embodiment, a decompression means (not shown) is connected to the space S, and the decompression means can reduce the pressure to a predetermined pressure.
The operation of the crystal growth apparatus 50 according to this embodiment will be described below with reference to FIG.

  Now, in the state of FIG. 2A, a plurality of substrates, for example, silicon carbide substrates, are arranged in a substantially horizontal state on each shelf plate 58a of the susceptor constituting member 58. A susceptor constituting member 58 on which substrates are arranged is integrally and detachably attached on a lower heat insulating member 66 made of a reflecting plate 66a. The space S is depressurized to a predetermined pressure by the depressurizing means.

  When the susceptor constituting member 58 is set in the space S thus depressurized as shown in FIG. 2A, the radiation member 56 is induction-heated by applying high-frequency power to the induction heating means 54 (not shown). The plurality of substrates are heated to 1500 ° C., for example. This makes it possible to grow an epitaxial layer on the substrate.

Then, a predetermined reaction gas is introduced into the gas supply pipe 52 from the upper side of the figure, the reaction gas is further introduced into the double cylinder through the opening 72a, and the reaction gas is further introduced into the horizontal direction via the gas introduction port 74. Is introduced into the susceptor constituting member 58 to supply a reactive gas to the surface of the substrate (not shown). Thereby, the crystal is grown.
Examples of the reaction gas include monosilane and propane.

  In this way, when the formation of the epitaxial layer by one process is completed, as shown in FIG. 2B, the lower end of the gas supply pipe 52 is opened, the shaft 59 is moved downward, and the susceptor configuration together with the shaft 59 is formed. The member 58 is taken out of the growth apparatus 50. From this state, the substrate accommodated in the susceptor constituting member 58 is replaced with a new one. In addition, when performing this replacement | exchange operation | work, it is preferable to drive the induction heating means 54 continuously and to heat the radiation member 56. FIG. If it does in this way, the temperature in space S can be maintained at a high temperature state.

Next, as shown in FIG. 2C, the shaft 59 is again moved up and set again.
In this way, since it is not necessary to raise or lower the temperature of the entire growth apparatus, the temperature raising time can be shortened.

  As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example at all. For example, in the above-described embodiment, the reaction gas is introduced from the upper side and the reaction gas is discharged from the lower side.

FIG. 1 is a cross-sectional view of a principal part showing a semiconductor crystal growth apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram sequentially illustrating work steps in the growth apparatus of FIG. 1, FIG. 2 (A) is a schematic diagram during the growth step of the epitaxial layer, and FIG. 2 (B) is a schematic diagram when replacing the substrate, FIG. 2C is a schematic view when the epitaxial layer is set to grow again. FIG. 3 is a sectional view of a conventional semiconductor crystal growth apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-12292. FIG. 4 is a sectional view of a conventional semiconductor crystal growth apparatus disclosed in Japanese Patent Laid-Open No. 9-330884.

Explanation of symbols

50 Crystal Device 52 Gas Supply Pipe 54 Induction Heating Means 56 Radiation Member 58 Susceptor Constituent Member 58 ′ Shelf Plate 59 Shaft 60 Power Means 62 Inner Thermal Insulation Material 66 Lower Thermal Insulation Member 68 Inner Cylinder 70 Outer Cylinder 72 Ceiling Surface 74 Gas Inlet 76 Gas Discharge port 78a Opening a Air layer S Space

Claims (2)

A gas supply pipe which is arranged in a vertical shape and into which a reaction gas is introduced in a limited space;
Induction heating means disposed on the outer peripheral surface of the gas supply pipe;
A radiating member having a bottomed cylindrical structure that is disposed on the inner peripheral side of the gas supply pipe so as to face the induction heating means, and a gas introduction port and a gas discharge port are respectively formed on opposite side wall surfaces;
A susceptor constituting member that is integrally supported by a shaft inserted inward of the radiation member and configured in a shelf shape so that a plurality of substrates can be placed in a substantially horizontal direction;
Power means for applying a rotational force and a moving force in a linear direction to a shaft that supports the susceptor component,
An inner heat insulating material is interposed between the gas supply pipe and the radiation member,
On the upper part of the radiating member, an upper heat insulating material is installed immovably,
Between the susceptor constituent member and the shaft, a lower heat insulating member in which a plurality of reflectors are placed in multiple stages is installed, and the susceptor constituent member is supported by the shaft via the lower heat insulating member,
The reaction gas is introduced from the upper part in the axial direction , passes through the outside of the radiation member, travels downward in the axial direction , and then is supplied in a substantially horizontal direction from the gas inlet toward the inside of the susceptor component, Fed from the gas outlet through the outside of the inner cylinder to the lower part in the axial direction, or
The reaction gas is introduced from the lower part in the axial direction, passes through the outside of the radiating member, travels upward in the axial direction, and then is supplied in a substantially horizontal direction from the gas inlet toward the inside of the susceptor component, An apparatus for growing a semiconductor crystal, wherein the semiconductor crystal growth apparatus is fed to the upper part in the axial direction from the gas outlet through the outside of the inner cylinder .   2. The semiconductor crystal growth apparatus according to claim 1, wherein decompression means is connected to the gas supply pipe.

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