JP5951517B2 - Silicon carbide semiconductor device manufacturing method and silicon carbide semiconductor device manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for manufacturing a silicon carbide semiconductor device provided with a silicon carbide semiconductor substrate having a trench, and an apparatus for manufacturing the silicon carbide semiconductor device.

  Conventionally, a semiconductor device such as a trench MOSFET having a trench is known. In such a semiconductor device such as a trench MOSFET, if the corner at the bottom of the trench is not rounded, the electric field is concentrated at the corner at the bottom of the trench. If the electric field concentrates in the corner portion at the bottom of the trench as described above, there is a concern that the gate dielectric breakdown voltage is lowered and the reliability of the semiconductor device is significantly lowered.

  For this reason, it is necessary to alleviate electric field concentration at the corner of the trench bottom by increasing the curvature of the corner at the bottom of the trench as much as possible. However, in a semiconductor device such as a trench MOSFET using silicon carbide, it is difficult to increase the curvature of the corner portion at the bottom of the trench by trench etching.

  In this regard, as a method for setting the sidewall angle of the trench to 90 degrees, a method of flowing a silane gas and performing a high temperature heat treatment in a silane gas atmosphere has been proposed (see Patent Document 1). More specifically, in Patent Document 1, a substrate having a silicon carbide epitaxial film formed on the surface of a silicon carbide single crystal substrate or a silicon carbide single crystal substrate is formed by, for example, dry etching to form a trench, and then the trench is formed. In the temperature range of 1600 ° C. to 1700 ° C. for 90 minutes or more, or 1700 ° C. to 1800 ° C. for 60 minutes or more in a mixed reduced pressure atmosphere of silane and argon.

  However, the method disclosed in Patent Document 1 is a method of setting the side wall angle of the trench to 90 degrees, and does not increase the curvature of the corner portion at the bottom of the trench. Further, since the silane gas used in Patent Document 1 is a flammable gas, sufficient care is required for its handling, and expensive incidental facilities such as an exhaust gas treatment device and a gas alarm system are required.

JP 2009-289987 A

  In view of the above points, in the silicon carbide semiconductor substrate having a trench, the present invention can increase the curvature of the corner portion at the bottom of the trench while ensuring safety without using expensive incidental equipment. A method for manufacturing a silicon carbide semiconductor device and an apparatus for manufacturing a silicon carbide semiconductor device are provided.

A method for manufacturing a silicon carbide semiconductor device according to the present invention includes:
Disposing a silicon carbide semiconductor substrate having a trench in an unsealed container so that the trench faces downward;
Disposing a silicon material in the non-sealed container below the silicon carbide semiconductor substrate so as to face the silicon carbide semiconductor substrate;
Flowing an inert gas into the non-sealed container;
Heating and melting the silicon material in the non-sealed container; and
Is provided.

In the method for manufacturing a silicon carbide semiconductor device according to the present invention,
The silicon material is a silicon piece,
A plurality of the silicon pieces are disposed;
Each silicon piece may be spaced apart in the horizontal direction.

In the method for manufacturing a silicon carbide semiconductor device according to the present invention,
The inert gas may flow from the bottom surface of the non-sealed container and flow out from the top surface of the non-sealed container.

In the method for manufacturing a silicon carbide semiconductor device according to the present invention,
In the step of heating and melting the silicon material, the silicon material may be heated at 1600 ° C. to 1800 ° C.

In the method for manufacturing a silicon carbide semiconductor device according to the present invention,
In the step of flowing in the inert gas, the inert gas may be flowed in such that the pressure in the non-sealed container is 3333 Pa to 86660 Pa.

In the method for manufacturing a silicon carbide semiconductor device according to the present invention,
The silicon carbide semiconductor substrate having the trench is arranged in the vertical direction in the non-sealed container so that the trench faces downward,
The silicon material may be arranged below each silicon carbide semiconductor substrate so as to face each silicon carbide semiconductor substrate.

In the method for manufacturing a silicon carbide semiconductor device according to the present invention,
A lid member that covers the silicon carbide semiconductor substrate in a horizontal direction may be provided between the silicon carbide semiconductor substrate and the silicon material located above the silicon carbide semiconductor substrate.

In the silicon carbide semiconductor substrate trench processing method according to the present invention,
The material of the lid member may be graphite.

An apparatus for manufacturing a silicon carbide semiconductor device according to the present invention comprises:
An unsealed container;
A substrate support portion provided in the non-sealed container and supporting a silicon carbide semiconductor substrate having a trench so that the trench faces downward;
A silicon material support portion provided in a lower side of the substrate support portion in the non-sealed container and supporting a silicon material so as to face the silicon carbide semiconductor substrate;
An inert gas supply unit for supplying an inert gas into the non-sealed container;
A heating unit for heating and melting the silicon material supported by the silicon material support unit;
Is provided.

In the silicon carbide semiconductor device manufacturing apparatus according to the present invention,
The silicon material is a silicon piece,
A plurality of the silicon pieces are disposed;
A plurality of recesses that are spaced apart in the horizontal direction and hold the plurality of silicon materials may be provided on the surface of the silicon material support portion.

In the silicon carbide semiconductor device manufacturing apparatus according to the present invention,
An inlet through which the inert gas flows is provided at the bottom of the non-sealed container;
An outlet through which the inert gas flows out may be provided on the top surface of the non-sealed container.

In the silicon carbide semiconductor device manufacturing apparatus according to the present invention,
A plurality of the substrate support portions are arranged in the vertical direction in the non-sealed container,
A plurality of the silicon material support portions are arranged in the vertical direction in the non-sealed container,
Each silicon material support portion is disposed below each substrate support portion,
Each substrate support portion may support the silicon carbide semiconductor substrate such that the trench faces downward.

In the silicon carbide semiconductor device manufacturing apparatus according to the present invention,
A lid member that covers the silicon carbide semiconductor substrate supported by the substrate support portion in a horizontal direction may be provided between the substrate support portion and the silicon material support portion located above the substrate support portion. .

In the silicon carbide semiconductor device manufacturing apparatus according to the present invention,
The material of the lid member may be graphite.

  According to the present invention, the trench of the silicon carbide semiconductor substrate is disposed in the non-sealed container so that the trench of the silicon carbide semiconductor substrate faces downward, and the silicon material is disposed below the silicon carbide semiconductor substrate. Are arranged opposite to each other. In addition, an inert gas flows into the non-sealed container to create an inert gas atmosphere surrounding the silicon carbide semiconductor substrate and the silicon material. For this reason, according to the present invention, the curvature of the corner portion of the trench bottom portion of the silicon carbide semiconductor substrate can be efficiently increased.

  Moreover, in this invention, inert gas is used and dangerous gas, such as silane gas, is not used. For this reason, safety can be ensured without using expensive incidental facilities such as an exhaust gas treatment device and a gas detection / alarm system.

FIG. 1 is a schematic configuration diagram of a silicon carbide semiconductor device manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is an upper plan view of a silicon material support portion used in the silicon carbide semiconductor device manufacturing apparatus according to the first embodiment of the present invention. FIG. 3A is a photograph of a trench before being processed by the method for manufacturing a silicon carbide semiconductor device according to the first embodiment of the present invention, and FIG. 3B is the silicon carbide semiconductor device. It is the photograph which image | photographed the trench after being processed with this manufacturing method. FIG. 4 is a schematic configuration diagram of an apparatus for manufacturing a silicon carbide semiconductor device according to the second embodiment of the present invention.

First Embodiment Hereinafter, a first embodiment of a method for manufacturing a silicon carbide semiconductor device and a device for manufacturing a silicon carbide semiconductor device according to the present invention will be described with reference to the drawings. Here, FIG. 1 to FIG. 3 are diagrams for explaining a first embodiment of the present invention. In addition, the method and apparatus for manufacturing a silicon carbide semiconductor device of the present embodiment are for processing a trench of silicon carbide semiconductor substrate W used in the silicon carbide semiconductor device.

<Device configuration>
First, the configuration of the trench processing apparatus for silicon carbide semiconductor substrate W according to the present embodiment will be described.

  The trench processing apparatus for silicon carbide semiconductor substrate W of the present embodiment is used for processing trench T of silicon carbide semiconductor substrate W used for manufacturing a semiconductor device such as a trench MOSFET. More specifically, the trench processing apparatus for silicon carbide semiconductor substrate W according to the present embodiment is used particularly for increasing the curvature of corner portion Tc at the bottom of the trench formed by dry etching (FIG. 3A). (See (b)). 3A is a photograph of trench T before being processed by the trench processing method for silicon carbide semiconductor substrate W according to the present embodiment, and FIG. 3B is the silicon carbide semiconductor substrate. It is the photograph which image | photographed the trench T after processing by the trench processing method of W.

  As shown in FIG. 1, the trench processing apparatus for silicon carbide semiconductor substrate W of the present embodiment includes a non-sealed container 10 and silicon carbide having a trench T provided in the non-sealed container 10 and formed by dry etching ( (SiC) A substrate support portion 26 that supports the semiconductor substrate W so that the trench T faces downward, and is provided in the non-sealed container 10 on the lower side of the substrate support portion 26 so as to face the silicon carbide semiconductor substrate W. And a silicon material holding portion 22 (corresponding to “silicon material support portion” in the claims) for supporting and holding a silicon piece which is a silicon material (Si). In the present embodiment, the following description will be made using a silicon piece as the silicon material, but the present invention is not limited to this.

  An example of the material of the non-sealed container 10 is carbon such as graphite. Further, as an example of the material of the silicon material holding part 22 and the substrate support part 26, carbon such as graphite can be cited. An example of the silicon carbide semiconductor substrate W is a semiconductor wafer made of silicon carbide. An example of the shape and size of the semiconductor wafer is a circular semiconductor wafer having a diameter of 4 inches (about 10 cm). Moreover, the distance in the up-down direction between the silicon carbide semiconductor substrate W supported by the board | substrate support part 26 and the silicon piece supported by the silicon material holding | maintenance part 22 is about 2-3 cm as an example.

  In the present embodiment, a gap is provided between the peripheral portion of silicon carbide semiconductor substrate W and the inner wall of non-sealed container 10, and between the peripheral portion of silicon material holding portion 22 and the inner wall of non-sealed container 10. There is a gap (see FIG. 2) so that an inert gas described later can pass through the gap. The silicon material holding portion 22 is supported by a support body 21 (four support bodies 21 in the embodiment shown in FIG. 2) provided on the inner wall of the non-sealed container 10. Note that carbon such as graphite can also be used as the material of the support 21.

  As shown in FIG. 1, an inert gas supply unit 35 that supplies an inert gas such as Ar into the non-sealed container 10 is connected to the non-sealed container 10. Moreover, the heating of the silicon piece held by the silicon material holding unit 22 is performed by, for example, an external heating unit (such as a high-frequency induction coil or a heating resistor provided around the non-hermetic container 10). The non-sealed container 10 is heated by high-frequency induction heating from 41, and the silicon material holding portion 22 is heated by the radiant heat of the non-sealed container 10. The heating temperature by high frequency induction heating can be adjusted as appropriate, and the heating temperature can be automatically or manually adjusted based on the temperature measured by the temperature measuring unit 47. In addition, as this temperature measurement part 47, a pyrometer can be used, for example. When the pyrometer is used in this way, for example, the temperature of the silicon piece can be indirectly measured by measuring the silicon material holding portion 22 in a non-contact manner (see FIG. 1).

  In the embodiment shown in FIG. 1, a detection window 44a for detecting infrared rays emitted from the silicon material holding portion 22 is provided on the bottom surface of the sealed container 10, and the silicon material holding portion 22 is provided via the detection window 44a. Infrared rays emitted from the light can be measured by the temperature measuring unit 47. Further, in the embodiment shown in FIG. 1, an opening 22b is provided at the center of the silicon material holding portion 22, and infrared rays emitted from the silicon carbide semiconductor substrate W are transmitted through the opening 22b to the temperature measuring portion. 47 can be measured.

  The silicon material holding portion 22 described above holds a plurality of silicon pieces in a plurality of recesses 23 (see FIG. 1). More specifically, as shown in FIG. 2, the surface of the silicon material holding portion 22 is provided with a plurality of concave portions 23 that are spaced apart at a uniform distance in the horizontal direction. And a silicon piece is arrange | positioned in each recessed part 23, and each silicon piece can be arrange | positioned uniformly spaced apart in a horizontal direction.

  In the present embodiment, for example, the heating temperature is adjusted so that the silicon piece and the silicon carbide substrate in the recess 23 are heated at 1600 ° C. to 1800 ° C. Since the melting point of silicon is about 1414 ° C., the silicon piece can be melted by heating the silicon piece at 1600 ° C. to 1800 ° C. in this way. Incidentally, the melting point of silicon carbide is about 2730 ° C. As the size and shape of the silicon piece used, various types can be used. As an example, a commercially available silicon wafer cut out to about 5 mm square can be used.

  As shown in FIG. 1, the non-sealed container 10 includes an inlet 31 for taking in an inert gas sent from an inert gas supply unit 35, and an outlet 39 for letting out the inert gas from the inside. have. Note that the gas flowing out from the outlet 39 includes a small amount of silicon gas evaporated from the silicon piece, but most of it is an inert gas.

  As shown in FIG. 1, in the present embodiment, the inlet 31 is provided at the “substantially center” of the bottom surface of the non-sealed container 10, and the outlet 39 is provided at the “substantially center” of the top surface of the non-sealed container 10. It has been. In the present embodiment, the outflow pipe 79 connected to the outlet 39 is provided with a pump 59 such as a rotary pump for discharging an inert gas and a small amount of silicon gas to the outside.

  By the way, in this Embodiment, it demonstrates using the aspect by which the inflow port 31 is provided in the approximate center of the bottom face of the non-sealed container 10, and the outflow port 39 is provided in the approximate center of the top face of the non-sealed container 10. However, it is not limited to this. For example, the inlet may be provided at a location other than the approximate center of the bottom surface of the non-sealed container 10, or the outlet may be provided at a location other than the approximate center of the top surface of the non-sealed container 10. Moreover, an inflow port may be provided below the side wall of the non-sealed container 10, and an outflow port may be provided above the side wall.

  As shown in FIG. 1, the outflow pipe 79 is provided with a pressure measurement unit 51 that measures the pressure inside the non-sealed container 10 by measuring the pressure in the outflow pipe 79. The inlet pipe 71 connected to the inflow port 31 is provided with a pressure adjusting unit 56 that adjusts the pressure inside the non-sealed container 10. The pressure inside the non-sealed container 10 can be adjusted by manually or automatically operating the pressure adjustment unit 56 based on the pressure measured by the pressure measurement unit 51. An example of the pressure adjusting unit 56 is a pressure adjusting valve. In the present embodiment, the pressure measurement unit 51 is described using an embodiment in which the outflow pipe 79 is provided. However, this is merely an example, and the pressure measurement unit 51 is provided in the non-sealed container 10. Alternatively, it may be provided in several places instead of one place.

  In the present embodiment, for example, the pressure of the inert gas flowing into the non-sealed container 10 by the pressure adjusting unit 56 so that the pressure in the non-sealed container 10 is 3333 Pa (about 25 Torr) to 86660 Pa (about 650 Torr). Is adjusted.

<Description of processing method>
Next, a process of processing trench T of silicon carbide semiconductor substrate W using the above-described trench processing apparatus for silicon carbide semiconductor substrate W will be described.

  Silicon carbide semiconductor substrate W having trench T is arranged on substrate support portion 26 in unsealed container 10 so that trench T faces downward.

  Before or after the silicon carbide semiconductor substrate W is arranged on the substrate support portion 26, in the plurality of recesses 23 of the silicon material holding portion 22 provided in the non-sealed container 10 and below the substrate support portion 26. A silicon piece is arranged in each of the above. Thus, a plurality of silicon pieces are arranged facing silicon carbide semiconductor substrate W. In addition, when the silicon piece used at the time of the process performed before the process to be performed still remains, the silicon piece may be used as it is.

  As described above, when a plurality of silicon pieces are arranged facing silicon carbide semiconductor substrate W, an inert gas flows into non-sealed container 10 from inflow port 31. The inert gas that has flowed into the non-sealed container 10 has passed through a gap (see FIG. 2) provided between the peripheral portion of the silicon material holding portion 22 and the silicon carbide semiconductor substrate W and the inner wall of the non-sealed container 10. Later, it flows out from the outlet 39. The pressure in the non-sealed container 10 is adjusted to be 3333 Pa (about 25 Torr) to 86660 Pa (about 650 Torr) as described above.

  Thus, in the situation where the inert gas flows in the non-sealed container 10, the silicon pieces in the plurality of recesses 23 of the silicon carbide semiconductor substrate W and the silicon material holding portion 22 start to be heated. As an example, the temperature is raised from room temperature to a predetermined temperature of 1600 ° C. to 1800 ° C. over about 10 minutes. Then, after being maintained at the predetermined temperature (1600 ° C. to 1800 ° C.) for 10 minutes, the temperature is lowered from the predetermined temperature to room temperature over several hours.

  In this way, during the predetermined temperature (1600 ° C. to 1800 ° C.), the curvature of the corner Tc at the bottom of the trench of the silicon carbide semiconductor substrate W gradually increases, and the corner Tc at the bottom of the trench is rounded. (See FIGS. 3A and 3B).

"effect"
Next, effects of the present embodiment configured as described above will be described.

  As shown in FIG. 1, in the present embodiment, silicon carbide semiconductor substrate W is arranged in non-sealed container 10 such that trench T faces downward, and a plurality of silicon carbide semiconductor substrates W are arranged below silicon carbide semiconductor substrate W. The silicon piece is arranged, and the trench T of the silicon carbide semiconductor substrate W and the silicon piece are arranged to face each other. In addition, the silicon piece is heated and melted at 1600 ° C to 1800 ° C. Further, an inert gas flows into the non-sealed container 10 to create an atmosphere of an inert gas surrounding the silicon carbide semiconductor substrate W and the silicon piece. For these reasons, according to the present embodiment, the curvature of corner portion Tc at the bottom of the trench of silicon carbide semiconductor substrate W can be efficiently increased. As a result, for example, in a semiconductor device such as a trench MOSFET, it is possible to prevent the gate dielectric breakdown voltage from being lowered.

  This point will be specifically described.

  As shown in FIG. 1, in the present embodiment, silicon carbide semiconductor substrate W is arranged such that trench T faces downward, and a silicon piece is arranged below silicon carbide semiconductor substrate W, so that silicon carbide is provided. The trench T and the silicon piece of the semiconductor substrate W are arranged to face each other. Further, the distance between silicon carbide semiconductor substrate W and the silicon piece is a short distance (for example, a distance of about 2 to 3 cm). Under such conditions, the silicon piece is heated and melted.

  For this reason, silicon (silicon gas) evaporated from the molten silicon piece can be directly brought into contact with the trench T at a short distance, and the curvature of the corner portion Tc at the bottom of the trench can be efficiently increased.

  If trench T and silicon piece are not opposed to each other (for example, silicon carbide semiconductor substrate W is disposed so that trench T faces upward), silicon gas wraps around silicon carbide semiconductor substrate W. However, the silicon gas concentration decreases toward the center side of the silicon carbide semiconductor substrate W, and the curvature of the corner portion Tc at the bottom of each trench cannot be increased uniformly. .

  When silicon contacts the surface of the trench T, the surface of the trench T is deformed so that the surface energy on the surface of the trench is reduced. Therefore, the curvature of corner portion Tc at the bottom of the trench can be naturally increased only by bringing silicon gas into contact with trench T of silicon carbide semiconductor substrate W.

  As described above, FIG. 3A is a photograph of the trench T before being processed by the trench processing method for the silicon carbide semiconductor substrate W according to the present embodiment, and FIG. Although it is the photograph which image | photographed the trench T after processing with the trench processing method of the silicon semiconductor substrate W, As evident from these photographs, using the trench processing method of the silicon carbide semiconductor substrate W by this Embodiment Thus, the curvature of the corner Tc at the bottom of the trench could be increased.

  In addition, if the distance between silicon carbide semiconductor substrate W and the silicon piece is too close (for example, about 1 cm), silicon carbide semiconductor substrate W and silicon raised on the silicon material holding portion may be in direct contact with each other. It is not preferable.

  In the present embodiment, an inert gas flows into the non-sealed container 10 from the inflow port 31, and the inert gas includes the silicon material holding part 22 and the peripheral part of the silicon carbide semiconductor substrate W and the inner wall of the non-sealed container 10. After passing through a gap (see FIG. 2) provided between the two and the outlet 39, the gas flows out from the outlet 39. For this reason, the silicon carbide semiconductor substrate W and the silicon material holding portion 22 can be surrounded by the inert gas, and a wall made of the inert gas can be formed. As a result, silicon evaporated from the silicon piece on silicon material holding portion 22 flows toward the periphery of silicon carbide semiconductor substrate W while coming into contact with the surface of trench T of silicon carbide semiconductor substrate W, and flows out from outlet 39. The At this time, silicon gas can be brought into contact with trench T of silicon carbide semiconductor substrate W, and the curvature of corner portion Tc at the bottom of the trench of silicon carbide semiconductor substrate W can be increased more efficiently.

  Note that the pressure of the inert gas flowing into the non-sealed container 10 is adjusted by the pressure adjusting unit 56 so that the pressure in the non-sealed container 10 is 3333 Pa (about 25 Torr) to 86660 Pa (about 650 Torr). This point has the following significance.

  When the pressure in the non-sealed container 10 is less than 3333 Pa, a large amount of silicon is evaporated from the silicon carbide semiconductor substrate W, which is not preferable. On the other hand, when the pressure in the non-sealed container 10 is higher than 86660 Pa, evaporation from the silicon piece is reduced, and the curvature of the corner portion Tc at the bottom of the trench cannot be increased efficiently. In addition, when the pressure in the non-sealed container 10 is higher than 86660 Pa, the pressure approaches the normal pressure (101325 Pa), so that there is a disadvantage that it is difficult to control the pressure.

  For this reason, setting the pressure in the non-sealed container 10 to 3333 Pa (about 25 Torr) to 86660 Pa (about 650 Torr) prevents the silicon carbide semiconductor substrate W from evaporating much while maintaining the silicon material. There is a technical significance and a critical significance that evaporation from silicon pieces on the portion 22 can be prevented from being reduced, and furthermore, the pressure in the non-sealed container 10 can be easily controlled. .

  Moreover, although the heating temperature by the external heating part 41 is adjusted so that a silicon piece may be heated at 1600 degreeC-1800 degreeC, this point has the following significance.

  When the temperature at which the silicon piece is heated is less than 1600 ° C., the silicon vapor cannot be sufficiently blown from the molten silicon piece, and the curvature of the corner portion Tc at the bottom of the trench cannot be sufficiently increased. On the other hand, when the temperature at which the silicon piece is heated is 1800 ° C. or higher, the silicon actively evaporates excessively from the molten silicon piece, making it difficult to appropriately control the processing of the corner portion Tc at the bottom of the trench. End up.

  For this reason, for the silicon piece to be heated at 1600 ° C. to 1800 ° C., the curvature of the corner portion Tc at the bottom of the trench of the silicon carbide semiconductor substrate W is sufficiently increased, and the processing of the corner portion Tc at the bottom of the trench is appropriate. There is a technical significance and a critical significance that can also be controlled.

  Moreover, in this Embodiment, since the inflow port 31 is provided in the bottom face of the non-sealed container 10, and the outflow port 39 is provided in the top surface of the non-sealed container 10, the inert gas which went to the top surface from the bottom face Can be made. For this reason, the wall of the inert gas surrounding silicon carbide semiconductor substrate W and silicon material holding part 22 can be formed with good balance in the horizontal direction. As a result, the curvature of corner portion Tc at the bottom of each trench T of silicon carbide semiconductor substrate W can be increased in a balanced manner.

  Further, in the present embodiment, the inflow port 31 is provided at the “substantially center” of the bottom surface of the non-sealed container 10, and the outflow port 39 is provided at the “substantially center” of the top surface of the non-sealed container 10. For this reason, the wall of the inert gas surrounding silicon carbide semiconductor substrate W and silicon material holding part 22 can be formed in a more balanced manner in the horizontal direction. As a result, the curvature of corner portion Tc at the bottom of each trench T of silicon carbide semiconductor substrate W can be further increased in a balanced manner.

  Further, as shown in FIG. 2, in the present embodiment, since the recesses 23 are provided on the surface of the silicon material holding portion 22 so as to be spaced apart at a uniform distance in the horizontal direction, They can be spaced apart uniformly in the horizontal direction. For this reason, silicon gas can be supplied to each trench T formed on the surface of silicon carbide semiconductor substrate W in a well-balanced manner. As a result, the curvature of corner portion Tc at the bottom of each trench T of silicon carbide semiconductor substrate W can also be increased in a balanced manner.

  If only one large piece of silicon is used, unlike the embodiment of the present embodiment, the molten silicon aggregates and a uniformly distributed silicon melting region is not formed, and the silicon melting region is biased. Therefore, silicon gas is locally generated from the silicon. For this reason, the concentration of the silicon gas decreases as the distance from the silicon melting region increases, and the curvature of the corner portion Tc at the bottom of each trench may not be increased uniformly.

Second Embodiment Next, a second embodiment of the present invention will be described.

  In the first embodiment, one silicon carbide semiconductor substrate W is a processing target. On the other hand, in the second embodiment, as shown in FIG. 4, a plurality (three in FIG. 4) of silicon carbide semiconductor substrates W are to be processed. A silicon material holding portion 22 is provided below each silicon carbide semiconductor substrate W, and a plurality of silicon pieces are held by a plurality of recesses 23 provided on the surface of the silicon material holding portion 22. .

  In the second embodiment, other configurations are substantially the same as those in the first embodiment. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, in the present embodiment, a plurality (three in FIG. 4) of substrate support portions 26 are arranged in the vertical direction in the non-sealed container 10, and the silicon material holding portions 22 are also in the non-sealed container 10. A plurality (three in FIG. 4) are arranged in the vertical direction. Each silicon material holding portion 22 is arranged below each substrate support portion 26. Each substrate support portion 26 supports silicon carbide semiconductor substrate W so that trench T faces downward.

  In the present embodiment, the substrate is interposed between the substrate support unit 26 (other than the substrate support unit 26 positioned at the uppermost position) and the support body 21 positioned above the substrate support unit 26 in the vertical direction. A substantially circular lid member 60 that covers the silicon carbide semiconductor substrate W supported by the support portion 26 in the horizontal direction is provided via the support body 27. For this reason, between the silicon carbide semiconductor substrate W (other than the uppermost silicon carbide semiconductor substrate W) and the silicon piece located above the silicon carbide semiconductor substrate W, the silicon carbide semiconductor substrate W is placed in the horizontal direction. The lid member 60 covered with can be provided. Various materials can be used as the material of the lid member 60. As an example, graphite can be used.

  In the embodiment shown in FIG. 4, a detection window 44a for detecting infrared rays emitted from the silicon material holding portion 22 is provided on the bottom surface of the sealed container 10, and the silicon material is held via the detection window 44a. The infrared rays emitted from the unit 22 can be measured by a temperature measuring unit 47 such as a pyrometer. In addition, another detection window 44b is provided on the bottom surface of the sealed container 10, and a detection window (or a detection hole) 21a is provided on the support body 21 located above the detection window 44b. 26 is provided with a detection window (or detection hole) 26a, and the support 27 is provided with a detection window (or detection hole) 27a. Then, the substrate support portion 26 ′ is provided via the detection window 44b, the detection window (or detection hole) 21a, the detection window (or detection hole) 26a, and the detection window (or detection hole) 27a. The infrared rays emitted from the thermometer can be measured by a temperature measuring unit 47 such as a pyrometer.

  According to the present embodiment, it is possible to simultaneously process a plurality of silicon carbide semiconductor substrates W while achieving the effects described in the first embodiment. The effects already described in the first embodiment will be described briefly.

  According to the present embodiment, a plurality of silicon carbide semiconductor substrates W having trenches T are arranged in the vertical direction so that trenches T face downward in unsealed container 10, and each silicon carbide semiconductor substrate W is below each silicon carbide semiconductor substrate W. Since the silicon piece is arranged so as to face silicon carbide semiconductor substrate W, the curvature of corner portion Tc at the bottom of the trenches of the plurality of silicon carbide semiconductor substrates W can be efficiently increased simultaneously.

  Further, according to the present embodiment, it is possible to form an inert gas wall surrounding the plurality of silicon carbide semiconductor substrates W and the plurality of silicon material holding portions 22 with the inert gas. For this reason, the curvature of corner part Tc of the trench bottom part of the some silicon carbide semiconductor substrate W can be enlarged more efficiently.

  Further, according to the present embodiment, the inert gas flowing into the non-sealed container 10 by the pressure adjusting unit 56 so that the pressure in the non-sealed container 10 is 3333 Pa (about 25 Torr) to 86660 Pa (about 650 Torr). The pressure is adjusted. For this reason, it is possible to prevent evaporation from silicon pieces on each silicon material holding portion 22 from decreasing while preventing silicon from evaporating from each silicon carbide semiconductor substrate W. Further, the pressure in the non-sealed container 10 can be easily controlled.

  Moreover, according to this Embodiment, the heating temperature is adjusted by the external heating part 41 so that the silicon piece on each silicon material holding | maintenance part 22 is heated at 1600 degreeC-1800 degreeC. Therefore, the curvature of corner portion Tc at the bottom of each silicon carbide semiconductor substrate W can be made sufficiently large, and the processing of corner portion Tc at the bottom of the trench can be appropriately controlled.

  Also in the present embodiment, since the inlet 31 on the bottom surface of the non-sealed container 10 is provided and the outlet 39 is provided on the top surface of the non-sealed container 10, the inert gas from the bottom surface toward the top surface is provided. Can be made. For this reason, the wall of the inert gas surrounding each silicon carbide semiconductor substrate W and each silicon material holding | maintenance part 22 can be formed with sufficient balance in a horizontal direction. As a result, the curvature of corner portion Tc at the bottom of each trench T of each silicon carbide semiconductor substrate W can be increased in a balanced manner.

  Further, in the present embodiment, the inflow port 31 is provided at the “substantially center” of the bottom surface of the non-sealed container 10, and the outflow port 39 is provided at the “substantially center” of the top surface of the non-sealed container 10. For this reason, the wall of the inert gas surrounding silicon carbide semiconductor substrate W and silicon material holding part 22 can be formed in a more balanced manner in the horizontal direction. As a result, the curvature of corner portion Tc at the bottom of each trench T of each silicon carbide semiconductor substrate W can be further increased in a balanced manner.

  Moreover, in this Embodiment, the recessed part 23 arrange | positioned by the uniform distance in the horizontal direction on the surface of each silicon | silicone material holding | maintenance part 22 is provided, and each silicon | silicone piece is spaced apart uniformly in the horizontal direction. Can be placed. For this reason, silicon gas can be supplied in a well-balanced manner from the silicon pieces in the recesses 23 of the corresponding silicon material holding portions 22 to the trenches T formed on the surface of each silicon carbide semiconductor substrate W. As a result, this also makes it possible to increase the curvature of corner portion Tc at the bottom of each trench T of each silicon carbide semiconductor substrate W in a well-balanced manner.

  Furthermore, in the present embodiment, lid member 60 is provided between silicon carbide semiconductor substrate W and silicon piece located above silicon carbide semiconductor substrate W (other than silicon carbide semiconductor substrate W located at the uppermost position). be able to. As a result, it is possible to prevent the silicon evaporated from the silicon piece from coming into contact with the silicon carbide semiconductor substrate W located below the silicon piece. Therefore, it is possible to prevent silicon from coming into contact with the surface of silicon carbide semiconductor substrate W at an unexpected location.

  Note that it is preferable to use graphite as the material of the lid member 60 because it can withstand high temperatures.

  Lastly, the description of the embodiments and the disclosure of the drawings described above are merely examples for explaining the invention described in the claims, and the description of the embodiments or the disclosure of the drawings described above is included. The invention described in the scope of claims is not limited by this.

10 Non-hermetic container 22 Silicone material holding part (silicone material support part)
23 concave portion 26 substrate support portion 31 inlet 35 inert gas supply portion 39 outlet 41 external heating portion 47 temperature measurement portion 51 pressure measurement portion 56 pressure adjustment portion 60 lid member 71 inflow pipe 79 outflow pipe T trench Tc corner of trench bottom Part W Silicon carbide semiconductor substrate

Claims (14)

Disposing a silicon carbide semiconductor substrate having a trench in an unsealed container so that the trench faces downward;
Disposing a silicon material in the non-sealed container below the silicon carbide semiconductor substrate so as to face the silicon carbide semiconductor substrate;
Flowing an inert gas into the non-sealed container;
Heating and melting the silicon material in the non-sealed container; and
A method for manufacturing a silicon carbide semiconductor device, comprising: The silicon material is a silicon piece,
A plurality of the silicon pieces are disposed;
2. The method for manufacturing a silicon carbide semiconductor device according to claim 1, wherein the silicon pieces are spaced apart in the horizontal direction.   The method for manufacturing a silicon carbide semiconductor device according to claim 1, wherein the inert gas flows in from a bottom surface of the non-sealed container and flows out from a top surface of the non-sealed container.   4. The method for manufacturing a silicon carbide semiconductor device according to claim 1, wherein in the step of heating and melting the silicon material, the silicon material is heated at 1600 ° C. to 1800 ° C. 5. .   5. The process according to claim 1, wherein, in the step of introducing the inert gas, the inert gas is introduced so that a pressure in the non-sealed container is 3333 Pa to 86660 Pa. 6. A method for manufacturing a silicon carbide semiconductor device according to claim 1. The silicon carbide semiconductor substrate having the trench is arranged in the vertical direction in the non-sealed container so that the trench faces downward,
6. The method of manufacturing a silicon carbide semiconductor device according to claim 1, wherein the silicon material is disposed below each silicon carbide semiconductor substrate so as to face each silicon carbide semiconductor substrate.   The lid member which covers the silicon carbide semiconductor substrate in the horizontal direction is provided between the silicon carbide semiconductor substrate and the silicon material located above the silicon carbide semiconductor substrate. A method for manufacturing a silicon carbide semiconductor device according to claim 1.   The method for manufacturing a silicon carbide semiconductor device according to claim 7, wherein a material of the lid member is graphite. An unsealed container;
A substrate support portion provided in the non-sealed container and supporting a silicon carbide semiconductor substrate having a trench so that the trench faces downward;
A silicon material support portion provided in a lower side of the substrate support portion in the non-sealed container and supporting a silicon material so as to face the silicon carbide semiconductor substrate;
An inert gas supply unit for supplying an inert gas into the non-sealed container;
A heating unit for heating and melting the silicon material supported by the silicon material support unit;
An apparatus for manufacturing a silicon carbide semiconductor device, comprising: The silicon material is a silicon piece,
A plurality of the silicon pieces are disposed;
10. The silicon carbide semiconductor device according to claim 9, wherein a plurality of recesses are provided on a surface of the silicon material support portion so as to be spaced apart from each other in the horizontal direction and hold the plurality of silicon materials. Manufacturing equipment. An inlet through which the inert gas flows is provided at the bottom of the non-sealed container;
11. The apparatus for manufacturing a silicon carbide semiconductor device according to claim 9, wherein an outlet through which the inert gas flows out is provided on a top surface of the non-sealed container. A plurality of the substrate support portions are arranged in the vertical direction in the non-sealed container,
A plurality of the silicon material support portions are arranged in the vertical direction in the non-sealed container,
Each silicon material support portion is disposed below each substrate support portion,
12. The apparatus for manufacturing a silicon carbide semiconductor device according to claim 9, wherein each substrate support portion supports the silicon carbide semiconductor substrate such that the trench faces downward.   A lid member that covers the silicon carbide semiconductor substrate supported by the substrate support portion in a horizontal direction is provided between the substrate support portion and the silicon material support portion located above the substrate support portion. The manufacturing apparatus of the silicon carbide semiconductor device of Claim 12 characterized by these.   The silicon carbide semiconductor device manufacturing apparatus according to claim 13, wherein a material of the lid member is graphite.