JP2016127201A - Method for manufacturing silicon carbide epitaxial substrate and method for manufacturing silicon carbide semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily confirm the presence of a crystal defect in an epitaxial layer.SOLUTION: A single crystal substrate 1 which is made from a silicon carbide and has a plurality of micropipes is prepared. An epitaxial layer 3 which is made from a silicon carbide and receives at least some out of the plurality of micropipes 2 is formed on the single crystal substrate 1. The epitaxial layer 3 is formed by epitaxial growth using a material gas containing Si atoms and C atoms so as to make a ratio of the C atoms to the Si atoms become 1.0 or more and 1.5 or less, on the single crystal substrate 1 heated at a growth temperature of 1630°C or more and 1680°C or less, and with a growth rate 1 μm/h or more and 5 μm/h or less.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for manufacturing a silicon carbide epitaxial substrate and a method for manufacturing a silicon carbide semiconductor device.

  A silicon carbide single crystal has excellent physical properties such as a high dielectric breakdown electric field strength and a high thermal conductivity as compared with a silicon single crystal that has been widely used conventionally. For this reason, it is anticipated that the performance of a semiconductor device will be improved by using a silicon carbide substrate, and in particular, improvement of energy saving performance in a power device is expected.

  Although silicon carbide is represented by the same chemical formula SiC, there are crystal polymorphs having different crystal structures. Specifically, there are 2H, 3C, 4H, 6H, 8H, and 15R types. Among these, 4H-type silicon carbide is particularly suitable for use in power devices that handle large voltages. In the 4H type, the band gap is as large as 3.26 eV, and the anisotropy of electron mobility between the direction parallel to the c-axis and the direction perpendicular thereto is small. These characteristics are advantageous as a substrate for power devices. In the name “4H”, “H” indicates that the crystal polymorph is hexagonal (Hexagonal), and “4” indicates that the basic unit structure along the c-axis of the hexagonal system is Si (silicon). ) And C (carbon), which is composed of four layers of diatomic layers.

  As described above, the physical properties differ depending on the crystal polymorph. For this reason, in order to obtain as many silicon carbide semiconductor elements as possible from a single substrate, it is necessary to increase the diameter of the substrate and to make the entirety of a single crystal polymorph. Generally, a single crystal silicon carbide substrate is obtained by cutting from a single crystal ingot. A single crystal ingot is manufactured by a method (sublimation method) in which a raw material containing Si and C is sublimated in a crucible and grown on a seed crystal using the sublimated raw material. This manufacturing technology has been improving year by year. Conventionally, a substrate with a diameter of about 100 mm (4 inches) has been mainly used, but now, a substrate with a diameter of about 150 mm (6 inches) at the maximum is now available on the market. ing. However, they are usually very dense and have crystal defects. Typical crystal defects include threading screw dislocations, threading edge dislocations, basal plane dislocations, stacking faults, and the like. For this reason, attempts have been made to reduce crystal defects.

  When a silicon carbide semiconductor device is manufactured using the single crystal substrate (also referred to as a bulk substrate), an active layer is often formed on the bulk substrate. By controlling the impurity concentration of the active layer, the withstand voltage and device resistance of the device can be adjusted. The active layer is obtained by epitaxially growing silicon carbide on a substrate, and is usually produced by a chemical vapor deposition (CVD) method using a source gas containing Si atoms and C atoms. That is, a structure having a bulk substrate and an epitaxial layer formed thereon (also referred to as an epitaxial substrate) is prepared for manufacturing a semiconductor device.

  It is known that when the epitaxial substrate is formed, the above-described crystal defects of the bulk substrate propagate into the epitaxial layer, thereby adversely affecting the operation of various semiconductor devices. Among crystal defects, what is called a micropipe is particularly likely to be an obstacle in manufacturing a silicon carbide semiconductor device. The micropipe is a crystal defect that propagates in the c-axis direction of hexagonal silicon carbide, and its inside is hollow. For this reason, in a semiconductor element using an epitaxial substrate having a {0001} plane perpendicular to the c-axis or a plane having an off angle of about several degrees with respect to this plane as the plane orientation, the above hollow structure Is likely to adversely affect by extending along the thickness direction. Specifically, the initial characteristics may be significantly deteriorated such that a desired withstand voltage cannot be achieved. Although the number of micropipes in the bulk substrate has been reduced by the improvement of the substrate manufacturing technique by the sublimation method, it is difficult to completely eliminate the micropipes at present.

  Since micropipes are unavoidably present as described above, when a plurality of semiconductor elements are fabricated on one substrate, some of these elements formed on the micropipes may be defective. . As a result, the number of semiconductor elements that can be taken from one substrate is reduced. That is, the yield decreases due to the macro pipe. For this reason, it has been studied to reduce the number of micropipes in the epitaxial layer by preventing the micropipes from propagating from the bulk substrate to the epitaxial layer in the epitaxial growth on the bulk substrate. For example, according to International Publication No. 2003/078702 (Patent Document 1), when an epitaxial layer is formed on a silicon carbide substrate by so-called step flow growth using a CVD method, the micropipe is closed to form a plurality of threading screw dislocations. Is disclosed. In addition, attempts have been made to close the micropipe.

International Publication No. 2003/078702

  When the micropipe is closed during epitaxial growth for manufacturing an epitaxial substrate, electrical characteristics such as leakage current are remarkably improved when a semiconductor device is manufactured using this epitaxial substrate. For this reason, it has been considered preferable to close the micropipe as shown in the above prior art. However, studies by the present inventors have revealed that blocking the micropipe has an adverse effect on long-term reliability, although it is useful for avoiding the initial failure of the semiconductor device.

  Testing long-term reliability for all industrially mass-produced semiconductor devices is not practical. Therefore, considering not only initial defects but also long-term reliability, the method of converting micropipes into threading screw dislocations, which are other types of crystal defects, in the epitaxial layer as in the conventional technique described above is an appropriate solution. I can't say that. Therefore, it is considered to be important to have a screening technique for excluding a semiconductor device formed on a crystal defect as necessary, while allowing some crystal defects in the epitaxial substrate to be unavoidably present. For this purpose, a technique for more easily grasping the existence of crystal defects in the epitaxial layer is desired.

  Even if there is no intention to actively close the micropipe, if the relatively thick epitaxial layer required for the power device is formed on the bulk substrate by a conventional method, the micropipe is blocked at a non-negligible rate. It is thought that there were many things that were done. Even in such a case, the problem of long-term reliability may occur as described above.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide an epitaxial substrate manufacturing method capable of easily grasping the existence of crystal defects in an epitaxial layer. It is. Another object is to provide a method for manufacturing a silicon carbide semiconductor device capable of more reliably screening a silicon carbide semiconductor device manufactured using this epitaxial substrate.

  A method of manufacturing a silicon carbide epitaxial substrate of the present invention includes a step of preparing a single crystal substrate made of silicon carbide and having a plurality of micropipes, and a method of manufacturing a plurality of micropipes made of silicon carbide on a single crystal substrate. And a step of forming an epitaxial layer that inherits at least a part thereof. The step of forming the epitaxial layer is performed at a growth temperature of 1630 ° C. or higher and 1680 ° C. or lower using a source gas containing Si atoms and C atoms such that the ratio of C atoms to Si atoms is 1.0 or more and 1.5 or less. It is carried out by epitaxial growth at a growth rate of 1 μm / h or more and 5 μm / h or less on a single crystal substrate heated to 1 μm / h.

  A method of manufacturing a silicon carbide semiconductor device of the present invention includes a step of preparing a single crystal substrate made of silicon carbide and having a plurality of micropipes, and a method of manufacturing a plurality of micropipes made of silicon carbide on a single crystal substrate. Of these, the method includes a step of forming an epitaxial layer taking over at least a part thereof, and a step of forming an electrode electrically connected to the epitaxial layer. The step of forming the epitaxial layer is performed at a growth temperature of 1630 ° C. or higher and 1680 ° C. or lower using a source gas containing Si atoms and C atoms such that the ratio of C atoms to Si atoms is 1.0 or more and 1.5 or less. It is carried out by epitaxial growth at a growth rate of 1 μm / h or more and 5 μm / h or less on a single crystal substrate heated to 1 μm / h.

  According to the method for manufacturing a silicon carbide epitaxial substrate of the present invention, the crystal defects generated in the epitaxial layer due to the micropipes of the single crystal substrate are similarly micropipes at a high rate. Thereby, the presence of crystal defects in the epitaxial layer can be easily grasped.

  According to the method for manufacturing a silicon carbide semiconductor device of the present invention, the crystal defects generated in the epitaxial layer due to the micropipes of the single crystal substrate become micropipes at a high rate. The presence of the micropipe can be easily grasped by evaluating electrical characteristics using electrodes. Therefore, screening of the silicon carbide semiconductor device can be performed more reliably.

It is a flowchart which shows schematically the structure of the manufacturing method and screening method of a silicon carbide epitaxial substrate and silicon carbide semiconductor device in one embodiment of this invention. It is a perspective view which shows roughly the structure of the single crystal substrate prepared by step S10 of FIG. It is an enlarged view of the broken line part III of FIG. 1 is a perspective view schematically showing a configuration of a silicon carbide epitaxial substrate in one embodiment of the present invention. FIG. It is the enlarged view (A) of the broken line part VA of FIG. 4, and the enlarged view (A) of the broken line part VB. It is a graph which shows an example of the relationship between the continuation rate of a micropipe and growth temperature in step S30 of FIG. It is a graph which shows an example of the relationship between the continuation rate of a micropipe and the growth rate in step S30 of FIG. It is a graph which shows an example of the relationship between the continuation rate of a micropipe and C / Si ratio in step S30 of FIG. FIGS. 6A and 6B are views showing a state in which a semiconductor element is formed at each location in FIGS. 1 is a cross sectional view schematically showing a configuration of a silicon carbide semiconductor device in one embodiment of the present invention. FIG. 11 is a graph showing an example of electrical characteristic evaluation of the silicon carbide semiconductor device of FIG. 10.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a flowchart schematically showing a configuration of a silicon carbide epitaxial substrate and a semiconductor device manufacturing method and a screening method in the present embodiment. Hereinafter, the present embodiment will be described along steps S10 to S50 in the figure.

<Step S10: Preparation of Bulk Substrate>
Referring to FIG. 2, first, a bulk substrate (single crystal substrate) 1 (FIG. 2) is prepared. Bulk substrate (single crystal substrate) 1 is made of silicon carbide and has a single crystal structure. In the present embodiment, silicon carbide has a hexagonal crystal structure, more specifically, a 4H crystal polymorph. The surface orientation of the upper surface of the bulk substrate 1 preferably has an inclination (off angle) of 1 ° or more and 10 ° or less with respect to the (0001) plane. The off-angle azimuth is, for example, the <11-20> direction.

Referring to FIG. 3, bulk substrate 1 has a plurality of micropipes 2 (FIG. 2). The density of the micropipes ² on the upper surface of the bulk substrate 1 is, for example, about 10 cm ^{−2 to} 1000 cm ⁻² .

The bulk substrate 1 is preferably doped with impurities that contribute to electrical conduction. When the electrical conductivity is n-type, this impurity is typically nitrogen. The impurity concentration is, for example, about 1 × 10 ¹⁹ cm ⁻³ .

The bulk substrate 1 can be manufactured as follows. First, a silicon carbide single crystal ingot is formed by a sublimation method or the like. A bulk substrate 1 having a surface corresponding to the plane orientation is cut out from the ingot. Next, the surface of the bulk substrate 1 is mirror-finished. The surface roughness Ra of the mirror surface is preferably 0.5 nm or less, and more preferably 0.1 nm or less. The mirror finish can be performed by, for example, mechanical polishing or chemical mechanical polishing using acid or alkali. Next, surface cleaning of the bulk substrate 1 is performed in order to remove organic contamination, metal contamination, and the like. Specifically, immersion in a mixed solution of heated ammonia water and hydrogen peroxide solution, immersion in a mixed solution of heated hydrochloric acid and hydrogen peroxide solution, and an aqueous solution containing hydrogen fluoride. Immersion is performed in order. Then, a replacement process is performed with pure water. It should be noted that surface contamination with metal can cause new crystal defects during epitaxial growth. The H ₂ gas introduced into the growth furnace in the first stage of the epitaxial growth has an action of removing surface contamination, but the removed contaminant reduces the cleanliness in the growth furnace. Therefore, in order to maintain the cleanliness in the growth furnace, it is necessary to perform surface cleaning in advance as described above.

<Step S20: Confirmation of Micropipe Location>
The position of the micropipe 2 of the bulk substrate 1 is grasped. Unlike the threading screw dislocation 4, the position of the micropipe 2 having a hollow portion can be easily grasped. For example, an optical technique such as an optical microscope or a substrate surface inspection apparatus using a laser, or X-ray topography is used. The obtained position information is preferably stored in a computer or the like for use in screening described later.

<Step S30: Formation of Epitaxial Layer>
Referring to FIG. 4, epitaxial layer 3 made of silicon carbide is formed by epitaxial growth on bulk substrate 1. Thereby, epitaxial substrate 30 (silicon carbide epitaxial substrate) having bulk substrate 1 and epitaxial layer 3 provided thereon is obtained.

  Referring to FIG. 5A, the epitaxial layer 3 is obtained by taking over at least a part of the plurality of micropipes 2 of the bulk substrate 1. Referring to FIG. 5B, a part of the micropipes 2 of the bulk substrate 1 may be closed without being taken over by the epitaxial layer 3. The blocked micropipe 2 is decomposed into threading screw dislocations 4. The epitaxial layer 3 preferably takes over as much of the plurality of micropipes 2 of the bulk substrate 1 as possible, and specifically, it is preferred that 95% or more of micropipes are taken over. In other words, the number of threading screw dislocations 4 generated due to the blockage of the micropipe 2 is preferably smaller and more preferably not present at all. A method for forming the epitaxial layer 3 suitable for this purpose will be described in detail below.

  First, a dried bulk substrate 1 placed on a quartz susceptor is introduced into a reaction furnace of a horizontal hot wall type CVD apparatus (not shown). Next, the inside of the furnace is evacuated. Next, the bulk substrate 1 is heated to a growth temperature by heating the susceptor to a predetermined temperature by high-frequency induction heating. The growth temperature is from 1630 ° C. to 1680 ° C., preferably from 1650 ° C. to 1660 ° C.

Next, H ₂ is supplied into the furnace. H ₂ has a role of cleaning the surface of the bulk substrate 1 in addition to a role as a carrier gas of the source gas described later. As a result, processing alterations remaining on the surface and foreign matters existing in minute amounts on the surface are removed.

Subsequently, a source gas containing Si atoms and C atoms is introduced together with the H ₂ . The source gas contains Si atoms and C atoms such that the ratio of C atoms to Si atoms is 1.0 or more and 1.5 or less. The source gas includes, for example, SiH ₄ and C ₃ H ₈ . Further, nitrogen gas as an impurity gas can be simultaneously introduced for doping the epitaxial layer 3.

  On the bulk substrate 1 heated to the growth temperature, the epitaxial growth is performed at a growth rate of 1 μm / h or more and 5 μm / h or less by appropriately adjusting the flow rate and pressure of the source gas according to the capacity of the reaction furnace. Is called. Thereby, the epitaxial layer 3 is formed.

  FIG. 6 shows an example of the relationship between the growth temperature and the continuation rate when the growth rate is 5 μm / h and the C / Si ratio is 1.0. Here, the “continuation rate” refers to the ratio of the number of micropipes taken over in the epitaxial layer 3 to the number of micropipes in the bulk substrate 1. When the growth temperature exceeded 1700 ° C., the continuation rate of the micropipes was significantly reduced. Therefore, the growth temperature is preferably 1680 ° C. or lower and more preferably 1660 ° C. or lower in consideration of manufacturing stability. On the other hand, when the growth temperature is lower than 1600 ° C., surface unevenness called step bunching tends to be easily formed on the surface of the epitaxial layer 3. For this reason, the growth temperature is preferably 1630 ° C. or higher, more preferably 1650 ° C. or higher, considering production stability.

  FIG. 7 shows an example of the relationship between the growth rate and the continuation rate when the growth temperature is 1655 ° C. and the C / Si ratio is 1.0. The continuation rate decreased as the growth rate increased. That is, by growing at a relatively high speed, the micropipe tends to be blocked with a higher probability.

  The inventors also examined a growth rate of 10 μm / h. When the cross section of the obtained epitaxial substrate 30 was observed with a transmission electron microscope, the micropipe 2 of the bulk substrate 1 was immediately closed at the interface with the epitaxial layer 3, and a plurality of pieces from the closed portion into the epitaxial layer 3 were observed. The threading screw dislocation extended. This fact indicates that when the growth rate is high, Si atoms and C atoms adhere to the inside of the hollow holes of the micropipe 2 earlier than the layers are stacked according to the atomic arrangement of the micropipe 2 in the epitaxial growth. Suggests that it is occluded. In other words, it is considered that the micropipe 2 is closed so that the hollow hole is covered. In this case, since the large strain itself of the micropipe 2 is not eliminated, it is considered that a plurality of threading screw dislocations are generated from just above the blocked micropipe 2 so as to alleviate this strain.

  On the other hand, when the growth rate was 5 μm / h or less, the continuation rate was 95% or more. That is, most of the micropipes in the bulk substrate 1 were taken over by the epitaxial layer 3 without being blocked. The reason why the micropipe 2 does not close when the growth rate is low is that the deposition according to the atomic arrangement of the micropipe 2 is more in the epitaxial growth than the adhesion of Si atoms and C atoms to the inside of the micropipe 2. This is thought to be due to the superiority.

However, when the growth rate is less than 1 μm / h, epitaxial growth is difficult. The reason for this is considered to be that the etching action of the substrate surface by H ₂ occurred more remarkably. In addition, a growth rate smaller than 1 μm / h is often too small for mass production where production efficiency is required.

  From the above, it was found that the growth rate is preferably 1 μm / h or more and 5 μm / h or less.

  FIG. 8 shows an example of the relationship between the ratio of C and Si in the source gas (C / Si ratio) and the continuation rate when the growth temperature is 1655 ° C. and the growth rate is 5 μm / h.

  When the C / Si ratio was less than 1.0, the continuation rate suddenly decreased. Therefore, the C / Si ratio is desirably 1.0 or more. In particular, when the C / Si ratio was 1.1 or more, the continuation rate was 95% or more. The reason why the micropipe 2 is not blocked under the condition that C atoms are excessive as compared with Si atoms is that when step flow growth and helical growth occur in the vicinity of the micropipe 2 on the (0001) plane provided with an off angle. It is considered that the spiral growth centering on the micropipe 2 is more dominant due to the excessive presence of C atoms.

In this example, the impurity concentration of the epitaxial layer 3 was as low as 1 × 10 ¹⁵ cm ⁻³ or less under the condition that C was excessive as compared with Si. This is because the position where N (nitrogen) atoms as impurities are substituted is the position of C atoms, and therefore, when there are excessive C atoms in the source gas, it is difficult for N atoms to be taken into the epitaxial layer 3. It is thought to be.

  When the C / Si ratio was larger than 1.5, carbon (C) as a simple substance was precipitated in the epitaxial layer 3. For this reason, the C / Si ratio is preferably 1.5 or less, and 1.3 or less is considered more preferable in consideration of the ease of addition of impurities and the production stability.

  From the above, it is considered that the C / Si ratio is preferably 1.0 or more and 1.5 or less.

  In order for the micropipe 2 in the bulk substrate 1 to be succeeded to the epitaxial layer 3 more reliably, the off angle of the plane orientation of the bulk substrate 1 is preferably 1 ° or more and 10 ° or less with respect to the (0001) plane. More preferably, it is 8 ° or less. Since the off angle is not excessive, it is possible to avoid excessive step flow growth, which is a growth that easily closes the micropipe 2. On the other hand, if the off angle is too small, the growth surface tends to be rough.

<Step S40: Fabrication of Semiconductor Element and Evaluation of Electrical Characteristics>
Referring to FIGS. 9A, 9B, and 10, Schottky barrier diode 50 (silicon carbide semiconductor device) is formed as a semiconductor element in each of a plurality of chip regions 5 on epitaxial substrate 30. Specifically, the cathode electrode 10 is first formed on the bulk substrate 1 (on the lower surface of the epitaxial substrate 30 in FIG. 10). Next, Schottky electrode 11 (electrode) is formed on epitaxial layer 3. The Schottky electrode 11 is an electrode electrically connected to the epitaxial layer 3 by a Schottky junction. Next, an anode electrode is formed on the Schottky electrode 11.

  Subsequently, the electrical characteristics of the Schottky barrier diode 50 are evaluated. The electrical characteristic evaluation here may be general evaluation contents such as voltage dependency of forward current and leakage current.

  FIG. 11 is an example of an evaluation result of the relationship between the reverse voltage and the leakage current for each of the normal Schottky barrier diode 50 and the Schottky barrier diode 50 including the micropipe 2. This evaluation can be easily performed in a relatively short time. The leakage current of the device including the micropipe 2 was clearly larger than that of the normal device. Elements that exhibit such characteristics are excluded from the subsequent screening process.

<Step S50: Exclusion of element corresponding to micropipe position>
A screening step is performed to exclude the Schottky barrier diode 50 corresponding to the micropipe position previously grasped in step S20. Further, the Schottky barrier diode 50 formed on the micropipe 2 that has been overlooked in step S20 can be identified with a high probability with the result that the electrical characteristic evaluation in step S40 is poor. The Schottky barrier diode 50 thus specified is also excluded. Note that when the position of the micropipe 2 can be sufficiently determined by only one of step S20 and step S40, the other may be omitted.

<Effect>
According to the method for manufacturing the epitaxial substrate 30 of the present embodiment, the crystal defects generated in the epitaxial layer 3 due to the micropipes 2 of the bulk substrate 1 are also at a high rate, similarly to the micropipes 2 (FIG. 5A). It becomes. The presence of the micropipe 2 in the epitaxial layer 3 can be easily grasped in a short time, directly by observation or indirectly by evaluating the electrical characteristics of the element formed on the epitaxial layer 3. Therefore, crystal defects in the epitaxial layer 3 can be easily grasped at a high rate.

  The epitaxial layer 3 preferably inherits 95% or more of the plurality of micropipes 2 of the bulk substrate 1. Thereby, the existence of crystal defects in the epitaxial layer 3 can be grasped more reliably.

  The bulk substrate 1 preferably has a plane orientation having an off angle of 1 ° to 10 ° with respect to the (0001) plane. Thereby, the micropipe 2 of the bulk substrate 1 is reliably taken over by the epitaxial layer 3.

  Moreover, the threading screw dislocations 4 in the epitaxial layer 3 are reduced by selecting the parameters of the epitaxial growth conditions as described above. This prevents the long-term reliability of the semiconductor device manufactured using the epitaxial substrate 30 from deteriorating due to the threading screw dislocation 4. Further, the threading screw dislocations 4 are likely to affect many chip regions 5 (FIG. 9B). Therefore, the manufacturing yield of the semiconductor device can be increased by reducing the number of threading dislocations 4.

  According to the method for manufacturing Schottky barrier diode 50 (FIG. 10) of the present embodiment, the presence of micropipe 2 that has been overlooked in step S20 can be easily grasped by electrical characteristic evaluation using Schottky electrode 11. (See FIG. 11). Therefore, screening of the Schottky barrier diode 50 can be performed more reliably.

<Appendix>
The crystal structure of silicon carbide is not limited to the hexagonal crystal polymorph 4H type. As a hexagonal crystal polymorph, 2H or 6H may be used instead of 4H. Further, rhombohedral crystal polymorph 15R may be used instead of the hexagonal crystal polymorph.

  The silicon carbide semiconductor device is not limited to a Schottky barrier diode. The silicon carbide semiconductor device may be, for example, a field effect transistor, a pn junction diode, an IGBT (Insulated Gate Bipolar Transistor), or a laser diode. The effect described above is particularly great when the silicon carbide semiconductor device is a vertical power semiconductor device to which a high electric field is applied in the thickness direction of the epitaxial substrate.

  Further, the apparatus for epitaxial growth is not limited to the horizontal hot wall CVD apparatus, but may be a vertical hot wall CVD apparatus, for example. Further, it is expected that suitable parameters such as a growth temperature, a C / Si ratio, and a growth rate when performing epitaxial growth slightly vary depending on the size and structure of the CVD apparatus. In such a case, in each apparatus, various parameters may be set as appropriate so that spiral growth centering on micropipes is superior to step flow growth.

  In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention.

  1 Bulk substrate (single crystal substrate), 2 micropipe, 3 epitaxial layer, 30 epitaxial substrate (silicon carbide epitaxial substrate), 4 threading screw dislocation, 5 chip region, 11 Schottky electrode (electrode), 50 Schottky barrier diode ( Silicon carbide semiconductor device).

Claims (4)

Preparing a single crystal substrate made of silicon carbide and having a plurality of micropipes;
Forming an epitaxial layer made of silicon carbide and taking over at least a part of the plurality of micropipes on the single crystal substrate, wherein the step of forming the epitaxial layer includes C atoms relative to Si atoms. 1 μm on the single-crystal substrate heated to a growth temperature of 1630 ° C. or higher and 1680 ° C. or lower using a source gas containing Si atoms and C atoms so that the ratio of is 1.5 to 1.5. A method for manufacturing a silicon carbide epitaxial substrate, which is performed by epitaxial growth at a growth rate of not less than / h and not more than 5 μm / h.   The method for manufacturing a silicon carbide epitaxial substrate according to claim 1, wherein the epitaxial layer takes over 95% or more of the plurality of micropipes of the single crystal substrate.   The method for manufacturing a silicon carbide epitaxial substrate according to claim 1, wherein the single crystal substrate has a plane orientation having an off angle of 1 ° or more and 10 ° or less with respect to a (0001) plane. Preparing a single crystal substrate made of silicon carbide and having a plurality of micropipes;
Forming an epitaxial layer made of silicon carbide and taking over at least a part of the plurality of micropipes on the single crystal substrate, wherein the step of forming the epitaxial layer includes C atoms relative to Si atoms. 1 μm on the single-crystal substrate heated to a growth temperature of 1630 ° C. or higher and 1680 ° C. or lower using a source gas containing Si atoms and C atoms so that the ratio of is 1.5 to 1.5. A method of manufacturing a silicon carbide semiconductor device, comprising the step of forming an electrode that is formed by epitaxial growth at a growth rate of / h or more and 5 μm / h or less and is electrically connected to the epitaxial layer.

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