JP2009147118A - Method of manufacturing silicon carbide semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of heating a silicon carbide semiconductor substrate or the like for uniformly heating the silicon carbide semiconductor substrate for a short period of time by utilizing a fever of a suscepter. <P>SOLUTION: According to one embodiment, in the method of heating the silicon carbide semiconductor substrate, a silicon carbide semiconductor substrate 1 is heated in the state that plural carbon particles 2 are mounted on the silicon carbide semiconductor substrate 1 by only one layer. At this point, the silicon carbide semiconductor substrate 1 is mounted on a susceptor 13. Moreover, a heat treatment of the silicon carbide semiconductor substrate 1 is carried out by heating the susceptor 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a silicon carbide semiconductor device including a step of heating a silicon carbide semiconductor substrate.

  In order to activate the impurity region formed in the surface of the silicon carbide semiconductor substrate, the silicon carbide semiconductor substrate needs to be subjected to a high-temperature heat treatment. As the heat treatment of the silicon carbide semiconductor substrate, the following conventional techniques exist.

  In the first prior art, a carbon susceptor on which a silicon carbide semiconductor substrate is placed is inserted into a quartz tube. Here, the quartz tube after the insertion of the susceptor is in a vacuum or is filled with argon gas or the like. And after the said susceptor insertion, the temperature of the said susceptor is heated to 1600-1800 degreeC by high frequency induction heating. By receiving heat from the susceptor, heating of the silicon carbide semiconductor substrate is realized.

  The second prior art (see Patent Document 1) is an applied technique to the first prior art, and the specific contents are as follows. In the second prior art, a silicon carbide semiconductor substrate is placed on a susceptor, and a carbon heating element is brought into surface contact with the upper surface of the silicon carbide semiconductor substrate. Then, the susceptor and the heating element are heated by high frequency induction heating in a state where the heating element is in surface contact and covers the surface of the silicon carbide semiconductor substrate as described above. The silicon carbide semiconductor substrate is heated by receiving heat from the susceptor and the heating element.

JP 2005-197464 A

  By the way, the wavelength of infrared rays radiated at a temperature of 1600 to 1800 ° C. is distributed in a wavelength region of 1 to 10 microns (having a peak at about 2 microns) (non-patent document: heat transfer engineering data (revision 4)). Edition), published by Maruzen, pp 156). However, silicon carbide hardly absorbs infrared rays in the wavelength range (Non-patent document: Properties of Advanced Semiconductor Materials, John Wiley & Sons, Inc., pp 127).

  Therefore, in a vacuum, in the heating method according to the first conventional technique, the silicon carbide semiconductor substrate is heated by solid-solid heat conduction only from the point of contact with the susceptor that generates heat. It will be.

  The contact surfaces of the silicon carbide semiconductor substrate and the susceptor usually have a warp rather than a perfect plane. Therefore, the entire contact surface between the silicon carbide semiconductor substrate and the susceptor is not in contact, and the contact is about several points (theoretically, three points). For this reason, the heating state of the silicon carbide semiconductor substrate varies from the susceptor depending on the number of contact points and the contact location between the silicon carbide semiconductor substrate and the susceptor. In addition, since the number of contact points is small, heat is transmitted only from that point, so it is necessary to transfer heat through the substrate, and heating takes time.

  Further, in the gas atmosphere, in addition to the solid-solid heat conduction between the silicon carbide semiconductor substrate and the susceptor, there is also the solid-gas-solid heat conduction through the gas between the susceptor and the silicon carbide semiconductor substrate. . In this case, the distance between the substrate and the susceptor at each point of the substrate and the susceptor varies depending on the flatness of the silicon carbide semiconductor substrate and the susceptor. For this reason, effective thermal conductivity and a heating state will change.

  In summary, in the case of the first prior art, the silicon carbide semiconductor substrate cannot be heated uniformly, and since it is heated only from the contact portion, the heat supply from the susceptor to the silicon carbide semiconductor substrate is long. The problem of taking time arises. In addition, there is a problem that thermal stress is generated due to uneven heating and the substrate is cracked.

  In addition, when the silicon carbide semiconductor substrate reaches a high temperature, silicon atoms and carbon atoms constituting the silicon carbide semiconductor substrate are sublimated at their respective sublimation rates. Each of the sublimated atoms jumps out in a vacuum or an argon gas atmosphere, and as a result, the composition ratio of silicon atoms and carbon atoms on the surface of the silicon carbide semiconductor substrate is changed. That is, in the case of the first prior art, there is also a problem that the surface roughness of the silicon carbide semiconductor substrate is caused by sublimation. In the heating method according to the second prior art, it is described that sublimation of silicon atoms and the like is suppressed because the surface of the silicon carbide semiconductor substrate is covered with a heating element.

  By the way, in order to exhibit the above sublimation suppressing effect, it is premised that the heating element and the silicon carbide semiconductor substrate, and the susceptor and the silicon carbide semiconductor substrate are in a surface contact state. In order to enable the surface contact state, in order to improve the flatness, eliminate surface irregularities, make the surface roughness very good, and correct the warped silicon carbide semiconductor substrate to a flat surface In addition, it is necessary to correct the substrate by applying an external force.

  However, it is very difficult to improve the flatness of each member until the surface is brought into a complete surface contact state. Further, by pressing the silicon carbide semiconductor substrate by applying an external force, there is a possibility of damaging the device forming surface which is important for device operation, and the device yield is lowered.

  As described above, in the second prior art, in order to suppress sublimation of silicon atoms or the like, it is necessary to perform a process having a difficulty of completely bringing into a surface contact state, or damage to a device formation surface. There is a problem that it must be given.

  In view of the above, an object of the present invention is to provide a method for heating a silicon carbide semiconductor substrate capable of heating the silicon carbide semiconductor substrate uniformly in a short time by using heat generated by the susceptor. Further, a method for heating a silicon carbide semiconductor substrate capable of suppressing sublimation of silicon atoms and carbon atoms without damaging the device formation surface of the silicon carbide semiconductor substrate without taking into account complicated or difficult processes. The purpose is to provide.

  In order to achieve the above object, a method for manufacturing a silicon carbide semiconductor substrate according to claim 1 according to the present invention includes a step of placing a silicon carbide semiconductor substrate on a susceptor and the same level as the silicon carbide semiconductor substrate. A step of adsorbing infrared absorbing particles on an adsorption plate of the same shape with the same size; a step of placing the infrared absorbing particles on the silicon carbide semiconductor substrate while adsorbing the infrared absorbing particles on the adsorption plate; A step of releasing the adsorption of the infrared absorbing particles, and a step of heating the silicon carbide semiconductor substrate.

  According to the method for manufacturing a silicon carbide semiconductor device of the present invention, a silicon carbide semiconductor substrate can be manufactured by heating the silicon carbide semiconductor substrate uniformly and having uniform electrical characteristics.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.

Embodiment 1 FIG.
A method for heating a silicon carbide semiconductor substrate, which is one step of the method for manufacturing a silicon carbide semiconductor device according to the present embodiment, will be described with reference to FIGS. First, FIG. 1 is a schematic cross-sectional view showing a state before introduction of a silicon carbide semiconductor substrate in an apparatus for heating the silicon carbide semiconductor substrate. As shown in FIG. 1, there is a cylindrical quartz tube 11, and a high frequency induction heating coil 12 is wound around the quartz tube 11. The carbon susceptor 13 is formed with a two-stage digging 131 that can be grasped as a recess as a whole. The diameter of the upper digging serving as the first recess is slightly larger than the diameter of silicon carbide semiconductor substrate 1. Further, the diameter of the lower digging which becomes the second recess is slightly smaller than the diameter of silicon carbide semiconductor substrate 1. That is, the two-stage digging is formed by an upper digging and a lower digging connected to the bottom of the upper digging and having a smaller opening width than the upper digging. Yes.

  Next, as shown in FIG. 2, silicon carbide semiconductor substrate 1 is placed on the bottom of the first recess formed on carbon susceptor 13. Thereby, the upper part of the lower digging is closed, and a semi-sealed space is formed. Silicon carbide semiconductor substrate 1 is placed such that the device formation surface of the silicon carbide semiconductor substrate faces the susceptor 13 side. In addition, the outer periphery of silicon carbide semiconductor substrate 1 is in contact with the bottom of the upper digging. Usually, no device is formed in most of the outer peripheral portion of silicon carbide semiconductor substrate 1. Moreover, you may form uneven | corrugated shape in the bottom part (namely, support part of the silicon carbide semiconductor substrate 1) of the upper digging. Thereby, since the contact area of silicon carbide semiconductor substrate 1 and the bottom of the upper digging can be reduced, it is possible to suppress heat from being transmitted to silicon carbide semiconductor substrate 1 from the contact portion.

Subsequently, as shown in FIG. 3, the disk-shaped silicon carbide semiconductor substrate 1 is placed on a disk-shaped suction disk 23 having the same size as that of the silicon carbide semiconductor substrate 1, and the particle diameter of 20 μm as infrared absorbing particles. The carbon particles 2 of a certain degree are adsorbed. The adsorbing plate 23 has a circular shape which is smaller than the particle size of the infrared absorbing particles 2 and about 80% of the particle size of the carbon particles 2 and is arranged at intervals of about 20 microns, which is the same as the particle size. A suction port 25 is formed.
The suction port 25 formed in the suction plate 23 is connected to the inside of the suction plate 23 and the vacuum line 24 connected to the side surface of the disk-shaped suction plate 23, and starts vacuuming of the vacuum line 24. Then, the carbon particles 2 are adsorbed on the adsorption board 23. The material of the suction disk 23 is a metal, which is processed using MEMS technology.

Next, as shown in FIG. 4, the suction disk 23 on which the carbon particles are adsorbed is moved directly above the silicon carbide semiconductor substrate 1.
Subsequently, the suction plate 23 on which the carbon particles 2 are adsorbed is moved immediately above the silicon carbide semiconductor substrate 1 and placed on the silicon carbide semiconductor substrate 1. In this state, the adsorption of the carbon particles 2 to the adsorption board 23 is released, that is, the evacuation of the vacuum line 24 connected to the adsorption board 23 is stopped. When the suction plate 23 is moved from above the silicon carbide semiconductor substrate 1, the carbon particles 2 are further separated on the back surface opposite to the device formation surface on the silicon carbide semiconductor substrate 1 by gravity as shown in FIG. 5. Will only be placed. In addition, when the particle size is reduced, the carbon particles 2 may be physically adsorbed on the adsorption plate 23 due to the influence of moisture in the air, and may not be separated by gravity. By introducing nitrogen, the carbon particles 2 can be reliably arranged on the silicon carbide semiconductor substrate 1.
Next, as shown in FIG. 6, a carbon susceptor cover 14 is disposed on the susceptor 13. A digging 141 is formed on the surface of the susceptor cover 14 facing the susceptor 13.

  Next, as shown in FIG. 7, the susceptor 13 and the susceptor cover 14 that have been subjected to the process are inserted into the cavity of the quartz tube 11. The silicon carbide semiconductor substrate 1 is heated by heating the susceptor 13 and the carbon susceptor cover 14 with the carbon particles 2 placed and introduced on the silicon carbide semiconductor substrate 1. The procedure for heating silicon carbide semiconductor substrate 1 is as follows. First, a current is passed through the high frequency induction heating coil 12. Then, a magnetic field is generated in the quartz tube 11. Then, an induced current flows in the carbonized susceptor 13 and the carbonized susceptor cover 14 by the magnetic field. When the induced current flows, the susceptor 13 and the susceptor cover 14 generate heat. In the above, the susceptor 13 and the heating element 10 generate heat, and the temperature of the susceptor 13 and the susceptor cover 14 becomes about 1600 to 1800 ° C. Then, infrared rays having a predetermined wavelength are radiated from the susceptor 13 and the susceptor cover 14.

  Here, as described in “Problems to be Solved by the Invention”, the silicon carbide semiconductor substrate 1 hardly absorbs infrared rays generated in the temperature range (Non-patent Document: Properties of Advanced Semiconductor Materials, John Wiley & Sons, Inc., pp 127). Therefore, most of the generated infrared light passes through silicon carbide semiconductor substrate 1. However, the carbon particles 2 can absorb infrared rays generated in the temperature range. Therefore, the carbon particles 2 absorb infrared rays radiated from the susceptor 13 and the susceptor cover 14, and as a result, the carbon particles 2 are heated. Here, a large number of carbon particles 2 are placed on silicon carbide semiconductor substrate 1. Therefore, carbon particles 2 and silicon carbide semiconductor substrate 1 are in point contact at a number of locations (see FIG. 7). As described above, the carbon particles 2 having an arbitrary particle size can be selected. If the size of silicon carbide semiconductor substrate 1 is 50 mm and the size of spherical carbon particles 2 is 100 μm, the number of contact points between silicon carbide semiconductor substrate 1 and carbon particles 2 is about 200,000. Further, when the size of the spherical carbon particles 2 is 10 μm, the number of contact points between the silicon carbide semiconductor substrate 1 and the carbon particles 2 is about 20 million points.

  As can be seen from this, as the carbon particles 2 having a smaller particle diameter are selected (adopted), the number of contact points between the silicon carbide semiconductor substrate 1 and the carbon particles 2 increases. If the number of contact points is increased not only in a vacuum but also in a gas atmosphere such as argon which has solid-gas-solid heat conduction, the heat conduction between the solid and the solid becomes dominant. Moreover, if the carbon particle 2 with a small particle diameter is selected (adopted), its volume will also decrease. When the volume of the carbon particles 2 is reduced, the heat capacity is reduced accordingly. Therefore, the temperature increase rate of the carbon particles 2 becomes faster. For this reason, the heat transfer efficiency from carbon particles 2 to silicon carbide semiconductor substrate 1 is improved, and the heat treatment of silicon carbide semiconductor substrate 1 can be completed in a short time.

  Further, as shown in FIG. 7, fine voids are formed between the adjacent carbon particles 2 and the silicon carbide semiconductor substrate 1. In a gas atmosphere such as argon gas, heat is transferred from the heated carbon particles 2 to the silicon carbide semiconductor substrate 1 by two heat conduction mechanisms of solid-solid and solid-gas-solid. As the particle diameter of the void also becomes smaller, the gap becomes smaller, the heat transfer performance in the gas improves, and it helps to finish the heat treatment earlier.

  The reason why the two carbon particle layers are formed is as follows. That is, when there are a plurality of carbon particles 2, it is considered that the infrared rays emitted from the susceptor 13 and the susceptor cover 14 are received by the carbon particles 2 of different layers and the efficiency is lowered. This is because the infrared rays emitted from the susceptor 13 and passed through the silicon carbide semiconductor substrate 1 are received by the carbon particles 2 in contact with the silicon carbide semiconductor substrate 1, but the infrared rays emitted from the susceptor cover 14 Since the carbon particles 2 receive light, the heat of the heated carbon particles 2 transfers heat to the underlying carbon particles 2 by heat conduction or radiation, and the carbonized particles in contact with the silicon carbide semiconductor substrate 1. Since 2 cannot be heated directly, it is thought that efficiency falls.

After completion of the heat treatment of silicon carbide semiconductor substrate 1 for a predetermined time, susceptor 13 and susceptor cover 14 on which silicon carbide semiconductor substrate 1 and carbon particles 2 are placed are taken out from quartz tube 11 and cooled to room temperature. After cooling, susceptor cover 14 is removed from susceptor 13, carbon particles 2 are blown off by blowing air, and silicon carbide semiconductor substrate 1 is taken out from susceptor 13. The carbon particles 2 may be removed by adsorption using the adsorption disk 23. Since these steps after heating are performed in the reverse order of the steps before heating, detailed description thereof is omitted.
By performing the heat treatment, silicon carbide semiconductor substrate 1 is uniformly heated.

  As described above, in the method for heating a silicon carbide semiconductor substrate according to the present embodiment, a large number of carbon particles 2 are placed on silicon carbide semiconductor substrate 1. And in the said state, the heat processing of the silicon carbide semiconductor substrate 1 using heat_generation | fever of susceptor 13 grade | etc., Are implemented. Therefore, the infrared rays radiated from the susceptor 13 and the susceptor cover 14 are once absorbed by the carbon particles 2. Here, as described above, carbon particles 2 are in point contact with silicon carbide semiconductor substrate 1 at a number of points (even if silicon carbide semiconductor substrate 1 has a warp, and plane of silicon carbide semiconductor substrate 1). Even when the degree is low, the point contact is realized at a large number of points). Therefore, silicon carbide semiconductor substrate 1 can be heated through carbon particles 2 in a short time and uniformly.

  In the present embodiment, a recess (more specifically, two levels of digging) is formed in the susceptor 13. Then, silicon carbide semiconductor substrate 1 is placed on the bottom of the recess (more specifically, the bottom of the upper digging), and in a recess formed by the upper surface of silicon carbide semiconductor substrate 1 and the side surface of the recess. A large number of carbon particles 2 are introduced. Therefore, silicon carbide semiconductor substrate 1 can be stably placed on susceptor 13 and a plurality of carbon particles 2 can be stably placed on silicon carbide semiconductor substrate 1 (that is, during the heat treatment). Even if some vibration occurs, the carbon particles 2 can be prevented from spilling from the silicon carbide semiconductor substrate 1).

  In the present embodiment, a plurality of carbon particles 2 are placed on the main surface facing the device formation surface of silicon carbide semiconductor substrate 1. Therefore, the device forming surface can be prevented from being contaminated by the carbon particles 2.

  In the present embodiment, the susceptor 13 is formed with the two-stage digging 131 as described above. Silicon carbide semiconductor substrate 1 is placed on the bottom of the upper digging so as to close the upper part of the lower digging. Therefore, silicon carbide semiconductor substrate 1 serves as a lower embedded lid, and the lower embedded region and substrate 1 form a semi-enclosed space. Thereby, silicon atoms and carbon atoms sublimated from the device formation surface 5 can be confined in the semi-sealed space. That is, sublimation of silicon atoms or the like can be saturated in the semi-enclosed space. Thus, when sublimation is saturated, sublimation from the device formation surface 5 does not occur. As described above, the silicon carbide semiconductor substrate 1 serves as a lower embedded lid, so that sublimation from the device formation surface can be suppressed. That is, the sublimation suppressing function can be exhibited without damaging the device forming surface 5 of the silicon carbide semiconductor substrate 1 without taking into account the steps having complexity and difficulty and also without applying an external force or the like. In addition, if the said sublimation is suppressed, it can suppress that the surface state of a device formation surface changes. Here, if the volume of the semi-enclosed space is reduced, the sublimation is saturated at an earlier stage, so that the effect of suppressing sublimation is further exhibited.

  Further, the device formation surface faces the susceptor 13 side. Therefore, the device forming surface can be prevented from being contaminated by foreign matters such as dust in the quartz tube 11.

  Usually, the outer peripheral portion of silicon carbide semiconductor substrate 1 becomes a frame portion and is a region where no device is formed. Further, as can be seen from the above aspect, the silicon carbide semiconductor substrate 1 and the susceptor 13 (more specifically, the upper embedded bottom) are only in contact with a part of the outer peripheral portion of the substrate 1. is there. That is, all or most of the region of the device formation surface 5 is not in contact with the susceptor 13 (more specifically, the bottom of the upper burying). Therefore, contamination of the device formation surface caused by contact with the susceptor 13 can also be prevented.

  In the present embodiment, carbon particles 2 are placed on silicon carbide semiconductor substrate 1 by one layer. Therefore, the layer thickness of the carbon particles 2 can be minimized. Thus, when the total volume of the carbon particle 2 decreases, the heat capacity of the entire layer of the carbon particle 2 decreases accordingly. Therefore, the temperature increase rate of the layer of carbon particles 2 becomes faster. For this reason, the heat transfer efficiency from carbon particles 2 to silicon carbide semiconductor substrate 1 is improved, and the heat treatment of silicon carbide semiconductor substrate 1 can be completed in a short time.

  In the present embodiment, a susceptor cover 14 is disposed above the carbon particles 2. The silicon carbide semiconductor substrate 1 is heated by heating the susceptor cover 14 and the susceptor 13. Therefore, the heat treatment of silicon carbide semiconductor substrate 1 can be completed in a shorter time.

  As shown in FIG. 7, a recess is formed on the susceptor cover 14 on the side facing the silicon carbide semiconductor substrate, and the lower surface of the susceptor cover 14 and the upper surface of the susceptor 13 come into contact with each other, and the silicon carbide semiconductor is formed by the recess. Although the example which heated silicon carbide semiconductor substrate 1 in the state where the upper surface of substrate 1 was covered was explained in this way, the lower surface of susceptor cover 14 at the time of heat treatment of silicon carbide semiconductor substrate 1 And the upper surface of the susceptor 13 can be prevented from being applied to the silicon carbide semiconductor substrate 1 via the carbon particles 2 due to the presence of the recess.

  Although not shown in the figure, the susceptor cover 14 is arranged so that the lower surface of the susceptor cover 14 and the upper surface of the susceptor 13 are in contact with each other with the lower surface of the susceptor cover 14 as a flat plate without digging in the susceptor cover 14 (that is, The carbonized susceptor cover 14 covers the carbonized susceptor 13 and / or the silicon carbide semiconductor substrate 1), and in this state, the heat treatment of the silicon carbide semiconductor substrate 1 utilizing the heat generated by the susceptor cover 14 and the susceptor 13 described above. May be applied. By performing heat treatment in a state where the lower surface of the susceptor cover 14 and the upper surface of the susceptor 13 are in contact with each other, heat generated by the susceptor cover 14 is more efficiently transmitted to the silicon carbide semiconductor substrate 1 through the carbon particles 2. can do.

  Further, the susceptor cover 14 and the susceptor 13 are arranged in a predetermined region in the cavity of the quartz tube 11 (that is, as shown in FIG. 7, the arrangement position of the susceptor cover 14 and the arrangement position of the susceptor 13). And are not distributed). Therefore, it is not necessary to wind the high-frequency induction heating coil 12 around the entire outer peripheral surface of the quartz tube 11, and a certain limited surface (that is, the susceptor cover 14 and the susceptor 13) is disposed in a solid state. It is only necessary to wrap around the surface corresponding to the area.

The size of the adsorbing port 25 may be any size as long as the carbon particles do not pass through. If the size is circular, the diameter is smaller than the particle size of the carbon particles, for example, 50 to 80% of the particle size of the carbon particles. However, it is not always necessary to have a circular shape as long as it has the same size. For example, if the particle diameter of the carbon particles 2 is 10 microns, the diameter or size of the suction port 25 may be about 5 to 8 microns.
Moreover, in this Embodiment, although the example of the carbon particle 2 was shown as an infrared rays absorption particle, it is not restricted to this, What is a material with a large absorption coefficient with respect to infrared rays with a wavelength of 2 to 3 microns? Also good.

Embodiment 2. FIG.
FIG. 8 is a schematic sectional view showing a silicon carbide semiconductor device according to the second embodiment for carrying out the present invention, and shows an example of a silicon carbide MOSFET (Metal Oxide Semiconductor Field Effect Transistor).
In FIG. 8, a p-type base region 32 and an n-type source region 33 formed by ion implantation are provided in an n-type silicon carbide drift layer 31 epitaxially grown on a film formation surface of an n-type silicon carbide semiconductor substrate 30. Source electrode 36 is provided on n-type source region 33, and gate insulating film 34 and gate electrode 35 are provided on n-type silicon carbide drift layer 31 in which ions are not implanted. A drain electrode 37 is provided on the surface opposite to the film forming surface of n-type silicon carbide semiconductor substrate 30.

Next, a method for manufacturing a silicon carbide MOSFET which is the silicon carbide semiconductor device of the present embodiment will be described in order with reference to FIG.
First, n-type silicon carbide drift layer 31 having a thickness of 5 to 50 microns is formed on n-type silicon carbide semiconductor substrate 30. Subsequently, an implantation mask is formed in the n-type silicon carbide drift layer 31 at a predetermined interval using a photolithography technique, and aluminum (Al) is ion-implanted to form a pair of p-type base regions 32. Form. The thickness of p type base region 32 does not exceed the thickness of n type silicon carbide drift layer 31, and the concentration of implanted Al exceeds the n type impurity concentration in n type silicon carbide drift layer 31. .
Further, an ion implantation mask used for forming the n-type source region 33 is formed, and nitrogen (N) ion implantation of an n-type impurity is performed to form the n-type source region 33. At this time, it is assumed that the thickness of the n-type source region 33 does not exceed the thickness of the p-type base region 32. Further, the n-type impurity concentration in the n-type source region 33 may be, for example, 1 × 10 ¹⁸ to 1 × 10 ²¹ cm ⁻³ .

  Next, the silicon carbide semiconductor substrate subjected to the above-described treatment is heat-treated at a high temperature of, for example, 1600 to 1800 ° C. for about 30 seconds to 1 hour by the method for heating the silicon carbide semiconductor substrate described in the first embodiment. Subsequently, a gate insulating film 34 made of a silicon dioxide film is formed on the n-type silicon carbide drift layer 31, the p-type base region 32, and the n-type source region 33. Next, a gate electrode 35 made of n-type polycrystalline silicon is formed on the gate insulating film 34 and patterned by using a photolithography technique. The gate electrode 35 is shaped such that a pair of p-type base region 32 and n-type source region 33 are located at both ends, and an n-type silicon carbide drift layer 31 exposed between the p-type base regions 32 is located in the center. Patterned. Further, the remaining portion of the gate insulating film 34 on each n-type source region 33 is removed by patterning and etching using a photolithography technique. Then, the source electrode 36 is formed and patterned at a portion where the n-type source region 33 is exposed on the surface. In addition, drain electrode 37 is formed on the back side of n-type silicon carbide semiconductor substrate 30. Note that the source electrode 36 and the drain electrode 37 may be made of aluminum, nickel, titanium, gold, or a composite thereof. Further, in order to reduce the contact resistance between the n-type source region 33 and the n-type silicon carbide semiconductor substrate 30, a heat treatment at about 1000 ° C. may be performed after the source electrode 36 and the drain electrode 37 are formed. This heat treatment step may also be performed by the method for heating the silicon carbide semiconductor substrate described in the first embodiment.

  Since silicon carbide MOSFET which is a silicon carbide semiconductor device manufactured in this way can heat n-type silicon carbide semiconductor substrate 30 at a uniform temperature, the implanted impurities can be activated uniformly, and an electrical current such as an on-current can be obtained. A silicon carbide semiconductor device having uniform characteristics and excellent characteristics is obtained.

It is a cross-sectional schematic diagram which shows the manufacturing process of the silicon carbide semiconductor device in Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the silicon carbide semiconductor device in Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the silicon carbide semiconductor device in Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the silicon carbide semiconductor device in Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the silicon carbide semiconductor device in Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the silicon carbide semiconductor device in Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process of the silicon carbide semiconductor device in Embodiment 1 of this invention. It is a cross-sectional schematic diagram of the silicon carbide semiconductor device in Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Silicon carbide semiconductor substrate, 2 Carbon particle, 11 Quartz tube, 12 High frequency induction heating coil, 13 Susceptor, 14 Susceptor cover, 23 Suction board, 24 Vacuum line, 25 Suction port, 30 n-type silicon carbide semiconductor substrate, 31 n Type silicon carbide drift layer, 32 p-type base region, 33 n-type source region, 34 gate insulating film, 35 gate electrode, 36 source electrode, 37 drain electrode, 131, 141 digging.

Claims (5)

Placing a silicon carbide semiconductor substrate on the susceptor;
A step of adsorbing infrared absorbing particles on the adsorption board;
Placing the infrared absorbing particles adsorbed on the adsorption plate on the silicon carbide semiconductor substrate;
Releasing the adsorption of the infrared absorbing particles to the adsorption plate;
A method for manufacturing a silicon carbide semiconductor device, comprising: heating the silicon carbide semiconductor substrate. The method for manufacturing a silicon carbide semiconductor device according to claim 1, wherein the infrared absorbing particles are carbon particles. The method for manufacturing a silicon carbide semiconductor device according to claim 2, wherein the carbon particles have a particle size of 100 microns or less. 2. The suction disk is provided with a suction port, wherein the suction port has a diameter smaller than the particle size of the infrared absorbing particles, and the suction ports are arranged at an interval equal to the particle size of the infrared absorbing particles. A method for manufacturing a silicon carbide semiconductor device according to claim 1. The method of manufacturing a silicon carbide semiconductor device according to claim 1, wherein the susceptor has a digging, and a silicon carbide semiconductor substrate is placed in the digging.

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