JP4916736B2 - Semiconductor crystal growth equipment - Google Patents

Description

The present invention relates to a formed ChoSo location of the 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. 7, 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 gas 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 gas 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.

Moreover, as shown in FIG. 8, what has arrange | positioned the gas supply pipe | tube vertically is also provided (patent document 2).
In this semiconductor crystal growth apparatus 10, the gas supply pipe 11 is arranged vertically, and the induction heating means 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.

  Further, in this growth apparatus 10, the reaction gas is introduced from the lower side of the apparatus main body and the reaction gas circulating around the upper side is discharged from the lower side. Such a growth apparatus 10 has a problem that the thickness of the obtained crystal varies.

In addition, in this growth apparatus 10, 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.
In addition, in the conventional growth apparatuses 10 and 100 shown in FIG. 7 and FIG. 8, the heat supply of the gas supply pipes 11 and 104 is not sufficient, the heat retention of the reaction chamber is impaired, and the crystal thickness and doping concentration can be obtained. There is a problem in that the quality of the crystals produced varies. Furthermore, there is a problem that it takes extra time and energy to raise the temperature once lowered.

On the other hand, in a crystal growth apparatus in which the supply direction of the reaction gas is vertical, a reaction gas supply port 8 is provided directly above the susceptor 3 as shown in FIG. In such a vertical crystal growth apparatus, a reaction gas is generally sprayed directly onto the substrate 4 from an air supply port 8 provided at the top (Patent Document 3).
JP 2001-122692 A Japanese Patent Laid-Open No. 9-330884 JP-A-5-335253

  By the way, when the reactive gas is sprayed from directly above the susceptor 3 as in Patent Document 3, the crystal formed on the substrate 4 grows faster as it is closer to the center of the rotating shaft 2. There was a problem that the growth rate varied.

In view of such circumstances, the present invention, for example, in growing a crystal on a large-diameter substrate, has good crystal film purity, and makes the crystal growth rate and doping concentration substantially constant at any position. and its object is to provide a formed ChoSo location of the semiconductor crystal as possible.

Apparatus for growing a semiconductor crystal according to the present invention for achieving the above object, the limited constant has been in space, a strong portion and a weak thermal influence of the induction heating means or a portion having strong flow of the reaction gas, And the weak portion is unevenly distributed so as to be displaced with respect to the central portion of the limited space, and the substrate is moved around in these environments, thereby increasing the crystal growth rate and the doping concentration in the substrate. Averaged as a whole.

According to the semiconductor crystal growth apparatus of the present invention, even if the crystal speed and the doping concentration are different, the substrate placed on the susceptor moves around the susceptor so that the variation in the diametrical direction is positive. Can be made uniform.

In addition, 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 from the outside in a limited space inside,
Induction heating means disposed in a helical shape on the outer peripheral surface of the gas supply pipe;
Said induction heating means disposed on the inner peripheral side of the gas supply pipe so as to face the, the one end portion side in the axial direction and the gas inlet and gas outlet you face each other in the axial direction the other A bottomed cylindrical radiating member formed on the end side ;
A susceptor that is integrally supported by a shaft inserted inward of the radiation member and configured to support a substrate in a substantially horizontal direction;
A power generation means for applying a rotational force and a moving force in a linear direction to a shaft supporting the susceptor, and a semiconductor crystal growth apparatus comprising:
A gas inlet into the radiation member of the gas supply pipe, that the gas discharge outlet to the radiation member outer from the radiation member was placed respectively at symmetrical positions other than the center portion of the gas supply tube It is a feature.

  According to such a manufacturing apparatus, the reaction gas is appropriately distributed without being concentrated in one place, and the substrate is rotated together with the susceptor, so that the film forming speed and the doping concentration are affected. Even if there is, it can be adjusted so as to positively uniform the variation.

Further, a semiconductor crystal growth apparatus according to the present invention is as follows:
A gas supply pipe which is arranged in a vertical shape and into which a reaction gas is introduced from the outside in a limited space inside,
One end side in the axial direction and the other end in the axial direction are arranged on the inner peripheral side of the gas supply pipe so as to face the induction heating means, and the gas introduction port and the gas discharge port face each other. A radiant member having a bottomed cylindrical structure formed on the portion side ;
A susceptor that is integrally supported by a shaft inserted inward of the radiation member and configured to support a substrate in a substantially horizontal direction;
A power generation means for applying a rotational force and a moving force in a linear direction to a shaft supporting the susceptor, and a semiconductor crystal growth apparatus comprising:
The induction heating means is provided in a part of the circumferential direction when the bottomed cylindrical structure radiating member is viewed in a cross-section in a direction orthogonal to the axial direction thereof .

According to such a growth apparatus, the heating of the induction heating means is in advance imbalance, by the inside could strength in heated state space substrate moves circularly, adjusting the temperature difference the substrate is subjected As a result, the film formation rate and the doping concentration in the diameter direction of the substrate can be made uniform.

According to the semiconductor crystal growth apparatus of the present invention, since the reaction gas supply or heating conditions are made different in advance, even if the growth rate and the doping concentration are affected, the substrate is circulated. The movement can reduce the difference and improve the uniformity of the crystal.

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 54. A cylindrical radiating member 56 with the ceiling surface closed, a shaft 59 inserted into the radiating member 56 from below, a susceptor 58 supported by the shaft 59, a shaft And a power means 60 for applying a rotational force and a linear moving force to 59.

  Further, in this 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 above the radiation member 56, and the lower heat insulating member 66 is provided on the lower surface of the susceptor 58. Are installed. The upper heat insulating material 64 is made of carbon fiber or the like, and is fixedly provided on the ceiling surface 72 of the radiation member 56.

  The upper heat insulating material 64 and the lower heat insulating member 66 improve the heat insulating property in the space S in the radiation member 56. Further, 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 radiation 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 cylindrical inner heat insulating material 62, and the lower side is insulated by the lower heat insulating member 66. The heat retention of the space S is very good.

  Specifically, the gas supply pipe 52 is formed of a quartz pipe and is arranged vertically so as not to be induction-heated. The induction heating means 54 is more specifically 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 closed bottom portion constitutes the ceiling surface 72. Thus, in this embodiment, since the radiation member 56 is formed in a double cylindrical shape, heating in the space S is promoted.

  The annular inner cylinder 68 and the annular outer cylinder 70 of the radiating member 56 are connected to each other, but an opening 72a is formed in the left upper region in FIG. 1, and the opening 72a communicates with the space S. Yes. On the other hand, the lower part of the opening 72 a is closed by a partition wall 72 c that connects the inner cylinder 68 and the outer cylinder 70. Furthermore, the upper region on the right side of the ceiling surface 72 in FIG. 1, that is, the symmetrical position of the opening 72 a is closed by a partition wall 72 b that constitutes a part of the ceiling surface 72. Further, the symmetrical position of the partition wall 72c is opened, and an opening 72d leading to the outside is formed here.

  As a result, the reaction gas supplied from the opening 72a in FIG. 1 is guided downward along the wall surface between the double cylinders 68 and 70 as shown by the arrows in the figure, and is sent out so as to spread in the space S. Thereafter, it is discharged to the outside through the opening 72d on the opposite lower right side.

  Thus, by forming such openings 72a and 72d in the radiating member 56, most of the reaction gas is guided so as to spread straight to the periphery at first, and then to the outside from the opening 72d. Will be discharged.

  The shaft 59 applies a rotational force and a linear moving force to the susceptor 58 by the force from the power unit 60. Therefore, during driving, a rotational force is applied to the shaft 59 by the power means 60, and thereby the substrate 71 on the susceptor 58 rotates in the space S.

  As described above, according to the present embodiment, the shaft 59 is driven to rotate and the reaction gas is blown against the substrate 71 from an oblique direction, so that there is a difference in the concentration and amount of the reaction gas. However, since the susceptor 58 moves uniformly in these regions, it is possible to positively promote uniform crystal growth on the substrate 71.

The susceptor 58 is configured so that one substrate 71 can be placed, but a plurality of substrates 71 may be placed by providing the susceptor in a shelf shape.
The operation of the semiconductor crystal growth apparatus 50 according to this embodiment will be described below with reference to FIG.

  2A, a substrate 71, for example, a silicon carbide substrate 71, is placed on the susceptor 58 in a substantially horizontal state. The space S is decompressed to a predetermined pressure by the decompression means, and the susceptor 58 is rotated by the shaft 59.

  When the susceptor 58 is set so as to be rotatable in the decompressed space S, the radiation member 56 is induction-heated by applying high-frequency power to the induction heating means 54, and the substrate 71 is heated to 1500 ° C., for example. . Then, as indicated by an arrow from the upper side of the figure, an epitaxial layer can be grown on the substrate 71 by introducing a predetermined reaction gas into the gas supply pipe 52 from the opening 72a into the double cylinder. Become.

  As described above, in this embodiment, the reaction gas is introduced unevenly from one side with respect to the substrate 71 on the susceptor 58, and the shaft 59 rotates in this state. Even if there is a difference, crystals grown on the substrate 71 are not partially accelerated. Further, when a difference in crystal speed or doping concentration occurs, positive reduction of the difference is promoted.

Examples of the reaction gas include monosilane and propane.
When the formation of the epitaxial layer is completed in this manner, 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 58 is moved together with the shaft 59 of the growth apparatus 50. Take it out. From this state, the substrate 71 accommodated in the susceptor 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.

  Further, in the above embodiment, the opening 72a and the opening 72d constituting the gas introduction port and the gas discharge port are provided as linear openings on a part of the side walls facing each other as shown in FIG. However, for example, as shown in FIG. 3B, the openings 72a and 72d may be provided in a semicircular arc shape. Further, as shown in FIG. 3C, the openings 72a and 72d may be small round holes. Thus, even if it is an opening like FIG. 3 (A)-FIG.3 (C), there can exist the same effect.

  FIG. 4 shows an outline of a substrate growth apparatus according to another embodiment of the present invention, in which the same elements as those in FIG. 1 are denoted by the same reference numerals. That is, in this growth apparatus 80, the axis of the induction heating means 54 is installed in an elliptical shape so as to deviate from the center of the concentric circles of the radiation member 56 and the susceptor 58.

If the susceptor 58 is rotationally driven in this state, the substrate on the susceptor 58 circulates alternately between the regions that are strongly affected by the heat induction 54 and the portions that are weakly affected. Thereby, for example, if the susceptor 58 rotates as indicated by an arrow, for example, a substrate (not shown) on the susceptor 58 circulates while being strongly heated or weakly heated by the induction heating means 54. As a result, even if there is a difference between the crystal growth rate and the doping concentration, the difference can be actively reduced. FIG. 5 shows the temperature distribution in the space S when the induction heating means 54 is arranged as shown in FIG. 4 in terms of the cross-sectional position in the major axis direction of the ellipse. The point O represents the central axis of the susceptor 58. Show.

  That is, as shown in FIG. 5A, when the substrate does not rotate, the temperature increases from the center O of the susceptor 58 closer to the induction heating means 54 (closer to the left side) and farther from the induction heating means 54. The temperature becomes lower (as it approaches the right side). However, when the substrate is rotated, as shown in FIG. 5B, the temperature in the space S is adjusted to be substantially constant regardless of the distance from the point O.

  In the present embodiment, the portion affected by the heat can be adjusted by adjusting the arrangement posture of the induction heating means 54 in this way. Alternatively, in adjusting the temperature distribution of the substrate by the induction heating means 54, the temperature distribution can also be adjusted by partially providing the arrangement position of the induction heating means 54 as shown in FIG. Can do.

  If the coil of the induction heating means 54 is arranged as shown in FIG. 6, the radiation member 56 is provided with both a part that is actively heated by the induction heating means 54 and a part that is not heated so much. If the susceptor 58 is rotationally driven, the thermal influence on the substrate changes periodically, so that the growth of the substrate can be made uniform.

  In order to adjust the growth rate and doping concentration of the substrate in this way, a portion having a strong thermal influence and a weak portion of the induction heating means 54 are provided in the space S, or a portion having a strong and weak reactive gas flow is provided. In addition to this, the substrate may be moved around. As described above, according to the method for manufacturing a semiconductor crystal and the apparatus for carrying out the method according to the present invention, the growth rate and doping concentration of the semiconductor crystal on the substrate can be adjusted substantially uniformly.

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. 3A to 3C are schematic cross-sectional views of the radiation member showing the gas introduction opening, the gas discharge opening formation region, and the shape thereof formed in the radiation member shown in FIG. . FIG. 4 is a cross-sectional view of an essential part of a semiconductor crystal growth apparatus according to another embodiment of the present invention. FIG. 5 explains the operation of the crystal growth apparatus shown in FIG. 4. FIG. 5 (A) is a graph showing the temperature distribution before rotating the substrate, and FIG. 5 (B) shows the state of FIG. It is a graph which shows temperature distribution at the time of rotating a board | substrate. FIG. 6 shows an outline of another crystal growth apparatus of the present invention, and is a schematic cross-sectional view of a main part when the induction heating means is limited to a part of the cylindrical member. FIG. 7 is a cross-sectional view of a conventional semiconductor crystal growth apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-12292. FIG. 8 is a sectional view of a conventional semiconductor crystal growth apparatus disclosed in Japanese Patent Laid-Open No. 9-330884. FIG. 9 is a schematic view of a conventional vertical crystal apparatus disclosed in Japanese Patent Laid-Open No. 5-335253.

Explanation of symbols

DESCRIPTION OF SYMBOLS 50 Crystal apparatus 52 Gas supply pipe 54 Induction heating means 56 Radiation member 58 Susceptor 59 Shaft 60 Power means 68 Inner cylinder 70 Outer cylinder 72 Ceiling surface 72a Opening 72d Opening 80 Crystal apparatus S Space

Claims (2)

A gas supply pipe which is arranged in a vertical shape and into which a reaction gas is introduced from the outside in a limited space inside,
Induction heating means disposed in a helical shape on the outer peripheral surface of the gas supply pipe;
Said induction heating means disposed on the inner peripheral side of the gas supply pipe so as to face the, the one end portion side in the axial direction and the gas inlet and gas outlet you face each other in the axial direction the other A bottomed cylindrical radiating member formed on the end side ;
A susceptor that is integrally supported by a shaft inserted inward of the radiation member and configured to support a substrate in a substantially horizontal direction;
A power generation means for applying a rotational force and a moving force in a linear direction to a shaft supporting the susceptor, and a semiconductor crystal growth apparatus comprising:
A gas inlet into the radiation member of the gas supply pipe, that the gas discharge outlet to the radiation member outer from the radiation member was placed respectively at symmetrical positions other than the center portion of the gas supply tube A semiconductor crystal growth apparatus. A gas supply pipe which is arranged in a vertical shape and into which a reaction gas is introduced from the outside in a limited space inside,
One end side in the axial direction and the other end in the axial direction are arranged on the inner peripheral side of the gas supply pipe so as to face the induction heating means, and the gas introduction port and the gas discharge port face each other. A radiant member having a bottomed cylindrical structure formed on the portion side ;
A susceptor that is integrally supported by a shaft inserted inward of the radiation member and configured to support a substrate in a substantially horizontal direction;
A power generation means for applying a rotational force and a moving force in a linear direction to a shaft supporting the susceptor, and a semiconductor crystal growth apparatus comprising:
An apparatus for growing a semiconductor crystal, characterized in that the induction heating means is provided in a part of a circumferential direction of the bottomed cylindrical structure radiating member as viewed in a cross section perpendicular to the axial direction thereof .

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