SILICON CARBIDE SINGLE CRYSTAL GROWTH APPARATUS AND METHOD FOR MANUFACTURING SILICON CARBIDE SINGLE CRYSTAL

Abstract

A silicon carbide single crystal growth apparatus including: a growth container including a growth container lid to which a seed crystal substrate is adhered and a growth container body for containing seed crystal substrate and a silicon carbide raw material; a heat-insulating container surrounding growth container; a temperature measuring equipment measuring a temperature inside growth container through a hole for temperature measurement provided in the heat-insulating container; and a heater heating the silicon carbide raw material, where a silicon carbide single crystal is grown on seed crystal substrate by heating and subliming silicon carbide raw material by a sublimation method, where growth container lid has a pattern that penetrates the growth container lid formed only within an adhesion region of the seed crystal substrate on the growth container lid. This provides an apparatus and manufacturing method that can suppress the generation of threading screw, basal plane, and threading edge dislocation.

Claims

1-8. (canceled)

9. A silicon carbide single crystal growth apparatus comprising: a growth container comprising a growth container lid to which a seed crystal substrate is adhered and a growth container body for containing the seed crystal substrate and a silicon carbide raw material; a heat-insulating container surrounding the growth container; a temperature measuring equipment for measuring a temperature inside the growth container through a hole for temperature measurement provided in the heat-insulating container; and a heater for heating the silicon carbide raw material, wherein a silicon carbide single crystal is grown on the seed crystal substrate by heating and subliming the silicon carbide raw material by a sublimation method, wherein the growth container lid has a pattern formed only within an adhesion region of the seed crystal substrate on the growth container lid, the pattern comprising at least one curved line or straight line that penetrates the growth container lid.

10. The silicon carbide single crystal growth apparatus according to claim 9, wherein the pattern is formed radially from a center of the growth container lid to which the seed crystal substrate is adhered.

11. The silicon carbide single crystal growth apparatus according to claim 9, wherein the pattern is formed concentrically.

12. The silicon carbide single crystal growth apparatus according to claim 9, wherein the pattern has a width of 5 mm or less.

13. The silicon carbide single crystal growth apparatus according to claim 10, wherein the pattern has a width of 5 mm or less.

14. The silicon carbide single crystal growth apparatus according to claim 11, wherein the pattern has a width of 5 mm or less.

15. A method for manufacturing a silicon carbide single crystal by growing a silicon carbide single crystal on a seed crystal substrate adhered to a growth container lid of a growth container by a sublimation method, wherein the silicon carbide single crystal is grown using, as the growth container lid, a growth container lid having a pattern formed only within an adhesion region of the seed crystal substrate, the pattern comprising at least one curved line or straight line that penetrates the growth container lid.

16. The method for manufacturing a silicon carbide single crystal according to claim 15, wherein the pattern is formed radially from a center of the growth container lid to which the seed crystal substrate is adhered.

17. The method for manufacturing a silicon carbide single crystal according to claim 15, wherein the pattern is formed concentrically.

18. The method for manufacturing a silicon carbide single crystal according to claim 15, wherein the pattern has a width of 5 mm or less.

19. The method for manufacturing a silicon carbide single crystal according to claim 16, wherein the pattern has a width of 5 mm or less.

20. The method for manufacturing a silicon carbide single crystal according to claim 17, wherein the pattern has a width of 5 mm or less.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0042] FIG. 1 is a schematic cross-sectional view showing an example of the inventive silicon carbide single crystal growth apparatus.

[0043] FIG. 2 is a flow diagram showing the inventive manufacturing method for manufacturing a silicon carbide single crystal.

[0044] FIG. 3 is a top view showing an example of the growth container lid of the inventive silicon carbide single crystal growth apparatus with a straight-line-shaped penetrating pattern formed.

[0045] FIG. 4 shows (a) a top view showing an example of the growth container lid of the inventive silicon carbide single crystal growth apparatus with a radial penetrating pattern formed, (b) a top view when a seed crystal substrate is adhered to an example of the growth container lid of the inventive silicon carbide single crystal growth apparatus with a radial penetrating pattern formed, (c) a cross-sectional view of FIG. 4 (a) at aa′ and bb′, and (d) a cross-sectional view of FIG. 4 (b) at aa′ and bb′.

[0046] FIG. 5 shows (a) a top view showing an example of the growth container lid of the inventive silicon carbide single crystal growth apparatus with a pattern of a combination of radial and concentric penetrating patterns formed, and (b) a top view showing a different example of the growth container lid of the inventive silicon carbide single crystal growth apparatus with a pattern of a combination of radial and concentric penetrating patterns formed.

[0047] FIG. 6 shows (a) a top view showing an example of the growth container lid of the inventive silicon carbide single crystal growth apparatus with composite penetrating patterns formed in addition to radial penetrating patterns, and (b) a top view when a seed crystal substrate is adhered to an example of the growth container lid of the inventive silicon carbide single crystal growth apparatus with composite penetrating patterns formed in addition to radial penetrating patterns.

[0048] FIG. 7 is a diagram showing an example of a conventional method for manufacturing a silicon carbide single crystal.

[0049] FIG. 8 is a diagram showing an example of a conventional silicon carbide single crystal growth apparatus.

[0050] FIG. 9 shows (a) a top view when a seed crystal substrate is adhered to an example of a conventional growth container lid, and (b) a cross-sectional view when a seed crystal substrate is adhered to an example of a conventional growth container lid.

[0051] FIG. 10 is a figure showing observation photographs of dislocation pits in the Example ((a) and (b)) and observation photographs of dislocation pits in the Comparative Example ((c) and (d)) in a defect selective etching using molten KOH.

DESCRIPTION OF EMBODIMENTS

[0052] Hereinafter, the present invention will be described in detail as an example of an embodiment with reference to the drawings, but the present invention is not limited thereto.

[0053] As described above, a warp that occurs in a seed crystal substrate leads to a bend in the basal plane of a silicon carbide single crystal and basal plane dislocation (BPD) and threading screw dislocation (TSD), etc. are generated occur in conventional technology. There has been a problem that the performance of devices that use a substrate manufactured from a silicon carbide single crystal having such dislocations present therein is considerably degraded.

[0054] The present inventors have earnestly studied and found out that when a pattern is formed only within an adhesion region of a seed crystal substrate on a growth container lid, the pattern including at least one curved line or straight line that penetrates the growth container lid, the generation of threading screw dislocation and basal plane dislocation can be suppressed, completing the present invention.

[0055] That is, the present invention is a silicon carbide single crystal growth apparatus including:

[0056] a growth container including a growth container lid to which a seed crystal substrate is adhered and a growth container body for containing the seed crystal substrate and a silicon carbide raw material;

[0057] a heat-insulating container surrounding the growth container;

[0058] a temperature measuring equipment for measuring a temperature inside the growth container through a hole for temperature measurement provided in the heat-insulating container; and

[0059] a heater for heating the silicon carbide raw material, where

[0060] a silicon carbide single crystal is grown on the seed crystal substrate by heating and subliming the silicon carbide raw material by a sublimation method, where

[0061] the growth container lid has a pattern formed only within an adhesion region of the seed crystal substrate on the growth container lid, the pattern including at least one curved line or straight line that penetrates the growth container lid.

[0062] Hereinafter, the inventive silicon carbide single crystal growth apparatus will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing an example of the inventive silicon carbide single crystal growth apparatus for manufacturing a silicon carbide single crystal. The inventive silicon carbide single crystal growth apparatus 100 is an apparatus for growing a silicon carbide single crystal 105 on a seed crystal substrate 104 by heating and subliming the silicon carbide raw material 106 by a sublimation method.

[0063] The inventive silicon carbide single crystal growth apparatus 100 shown in FIG. 1 is equipped with: a growth container 101 including a growth container lid 101a to which a seed crystal substrate 104 is adhered and a growth container body 101b for containing the seed crystal substrate 104 and a silicon carbide raw material 106; a heat-insulating container 102 surrounding the growth container 101; a temperature measuring equipment 108 for measuring the temperature inside the growth container 101 through a hole for temperature measurement 109 provided at the top of the heat-insulating container 102; and a heater 103 for heating the silicon carbide raw material 106.

[0064] The growth container 101 is formed from a graphite with heat resistance, for example.

[0065] FIGS. 3 to 6 are diagrams showing examples of the growth container lid 101a of the inventive silicon carbide single crystal growth apparatus 100.

[0066] The inventive silicon carbide single crystal growth apparatus 100 has a pattern 111 penetrating the growth container lid 101a formed only within the adhesion region 112 of the seed crystal substrate 104 on the growth container lid 101a as shown in FIGS. 4 (a) and (c). Examples of the shapes for the pattern 111 include: a straight line shape as shown in FIG. 3; a radial pattern as shown in FIG. 4 (a); a combination of a radial pattern and a concentric pattern as shown in FIGS. 5 (a) and (b); and a pattern with a composite pattern formed in addition to a radial pattern as shown in FIG. 6 (a). Furthermore, the pattern 111 penetrating the growth container lid 101a may have a combined shape of a straight-line-shaped, curved-line-shaped, radial, concentric, and winding pattern, etc. In this manner, the pattern 111 can have various shapes, but in all cases, the pattern 111 is made so that the pattern 111 does not protrude from the seed crystal substrate 104 when the seed crystal substrate 104 is adhered (see FIG. 4 (b) and FIG. 6 (b)). If the pattern 111 protrudes from the seed crystal substrate, raw material gas escapes to the back of the growth container lid, inhibiting the growth of the silicon carbide single crystal 105.

[0067] In this manner, it is considered that when a pattern 111 penetrating the growth container lid 101a is formed within the adhesion region 112 of the seed crystal substrate 104 adhered to the growth container lid 101a, the bend in the basal plane of the seed crystal substrate 104 can be resolved by elastic deformation of the seed crystal substrate 104 or silicon carbide single crystal 105 while growing and cooling even if a warp occurs. Thus, the generation of dislocation can be suppressed.

[0068] Furthermore, when the penetrating pattern 111 has such shapes as those shown in FIGS. 3 to 6, a uniform elastic deformation over the entire substrate is possible in the seed crystal substrate 104 and the silicon carbide single crystal 105, and therefore, the generation of threading screw dislocation and basal plane dislocation can be suppressed more certainly.

[0069] Furthermore, the width of the pattern 111 is preferably 5 mm or less (more than 0 mm and 5 mm or less). When the pattern width is 5 mm or less, the adhesive strength of the seed crystal substrate becomes sufficient, and there is no risk of falling.

[0070] In addition, when growing a silicon carbide single crystal 105, the crystal growth is performed in an inert gas atmosphere under reduced pressure by setting the growth container 101 inside an outer container 107 made from SUS or quartz and supplying an inert gas such as Ar or N.sub.2 while vacuum exhausting.

[0071] As the heater 103, a heater for performing RH (resistance heating) or RF (radiofrequency) heating can be used. In addition, by using a pyrometer as the temperature measuring equipment 108, temperature measurement can be performed with precision through the hole for temperature measurement 109 in the heat-insulating material from outside the growth container without contact.

[0072] A method for manufacturing a silicon carbide single crystal for manufacturing a silicon carbide single crystal 105 using the inventive silicon carbide single crystal growth apparatus 100 as described will be described using the flow diagram of FIG. 2.

[0073] Firstly, the silicon carbide raw material 106 is contained in the growth container body 101b as shown in FIG. 2 (a). Next, the seed crystal substrate 104 formed from silicon carbide is adhered to the growth container lid 101a having a pattern 111 penetrating the growth container lid 101a formed only within the adhesion region 112 of the seed crystal substrate 104 with, for example, a carbon adhesive 110 so that the pattern 111 portion is covered (see FIG. 4 (b), (d) and FIG. 6 (b)), and the seed crystal substrate 104 is contained in the growth container body 101b. Next, the growth container 101 including the growth container lid 101a and the growth container body 101b is disposed inside the heat-insulating container 102 as shown in FIG. 2 (b). Next, this is disposed inside the outer container 107 all together the heat-insulating container 102 as shown in FIG. 2 (c). Next, the inside of the outer container 107 is vacuumed, maintained at a predetermined pressure (for example, 1 to 20 Torr), and the temperature is raised to 2000 to 2300° C. as shown in FIG. 2 (d). Next, the silicon carbide single crystal 105 is grown on the seed crystal substrate 104 by the sublimation method as shown in FIG. 2 (e). Lastly, as shown in FIG. 2 (f), the pressure is raised to stop the sublimation, the growth is stopped, the temperature is gradually lowered, and cooling is performed.

[0074] By such a method for manufacturing a silicon carbide single crystal, the bend in the basal plane of the seed crystal substrate 104 can be resolved by elastic deformation of the seed crystal substrate 104 or silicon carbide single crystal 105 while growing and cooling even if a warp occurs. Thus, the generation of threading screw dislocation and basal plane dislocation can be suppressed, and therefore, a silicon carbide single crystal with a low dislocation density can be manufactured.

[0075] Furthermore, in this event, the pattern 111 is preferably formed radially from the center of the growth container lid 101a to which the seed crystal substrate 104 is adhered as shown in FIG. 4 (a).

[0076] When a growth container lid 101a having a penetrating pattern 111 with such a shape formed is used, a uniform elastic deformation over the entire substrate is possible in the seed crystal substrate 104 and the silicon carbide single crystal 105, and therefore, the bend in the basal plane of the seed crystal substrate 104 can be resolved. Thus, the generation of threading screw dislocation and basal plane dislocation can be suppressed more certainly.

[0077] In addition, in this event, the pattern 111 is preferably formed as a concentrically penetrating pattern.

[0078] When a growth container lid having a concentrically penetrating pattern 111 is used also, a uniform elastic deformation over the entire substrate is possible in the seed crystal substrate 104 and the silicon carbide single crystal 105, and therefore, the bend in the basal plane of the seed crystal substrate 104 can be resolved. Thus, the generation of threading screw dislocation and basal plane dislocation can be suppressed more certainly.

[0079] Furthermore, in this event, the pattern 111 preferably has a width of 5 mm or less (more than 0 mm and 5 mm or less).

[0080] When a growth container lid 101a formed with such a pattern 111 width is used, sufficient adhesive strength can be ensured between the seed crystal substrate 104 and the growth container lid 101a, and therefore, risk of the silicon carbide single crystal 105 coming off and falling is eliminated.

Example

[0081] Hereinafter, the present invention will be described more specifically with reference to an Example and a Comparative Example, but the present invention is not limited thereto.

Example

[0082] A silicon carbide seed crystal substrate with a 4-inch (101.6 mm) diameter was adhered to a growth container lid having a radially penetrating pattern formed as shown in FIG. 4, and a silicon carbide single crystal was grown according to the flow shown in FIG. 2. A silicon carbide single crystal substrate was sampled from the grown silicon carbide single crystal, and the densities of threading screw dislocation and basal plane dislocation were examined.

Comparative Example

[0083] With a silicon carbide seed crystal substrate having a 4-inch (101.6 mm) diameter, a silicon carbide single crystal was grown according to the flow shown in FIG. 7, using a growth container lid with no penetrating pattern formed. A silicon carbide single crystal substrate was sampled from the grown silicon carbide single crystal, and the densities of threading screw dislocation and basal plane dislocation were examined.

[0084] The examination results of the densities of threading screw dislocation (TSD) in the silicon carbide single crystal substrates in the Example and the Comparative Example are shown in Table 1, the examination results of the densities of basal plane dislocation (BPD) in Table 2, and the examination results of the densities of threading edge dislocation (TED) in Table 3.

[0085] In addition, observation photographs of dislocation pits in the Example are shown in FIGS. 10 (a) and (b), and observation photographs of dislocation pits in the Comparative Example are shown in FIGS. 10 (c) and (d) in a defect selective etching using molten KOH.

TABLE-US-00001 TABLE 1 Density of TSD Conventional example Example Min 3.307 0 Ave 6.531 28 Max 9.590 331 Unit; number/cm2

TABLE-US-00002 TABLE 2 Density of BPD Conventional example Example Min 1.238 0 Ave 4.341 14 Max 10.304 1.65 Unit; number/cm2

TABLE-US-00003 TABLE 3 Density of TED Conventional example Example Min 5.952 331 Ave 8.391 1.097 Max 12.897 2.811 Unit; number/cm2

[0086] As clearly seen from Table 1, Table 2, and Table 3, the Example had an extremely low result for every dislocation density compared with the Comparative Example, and all of the dislocation densities were improved considerably. In the Example, since a pattern penetrating the growth container lid was formed only within the adhesion region of the seed crystal substrate on the growth container lid, it was possible to resolve the bend in the basal plane of the seed crystal substrate by elastic deformation of the seed crystal substrate or silicon carbide single crystal while growing and cooling even if a warp had occurred. Thus, it was possible to suppress the generation of threading screw dislocation, basal plane dislocation, and threading edge dislocation.

[0087] In addition, as clearly seen from FIG. 10, the Example had a low result of etch pit density in the defect selective etching using molten KOH compared with the Comparative Example, and dislocation pits were reduced considerably.

[0088] It should be noted that the present invention is not limited to the above-described embodiments. The embodiments are just examples, and any examples that have substantially the same feature and demonstrate the same functions and effects as those in the technical concept disclosed in claims of the present invention are included in the technical scope of the present invention.