Carrier plate for epitaxial wafer growth and epitaxial equipment

Abstract

The utility model provides a carrying disc for epitaxial wafer growth and epitaxial equipment, the carrying disc comprises an annular frame and a chassis, the inner side of the annular frame is provided with an annular table extending towards the center side of the annular frame, an epitaxial wafer is erected on the upper end face of the annular table, and the chassis is placed below the annular table; and the annular table can support the epitaxial wafer warping downwards when the epitaxial wafer grows, and the maximum deformation position of the epitaxial wafer does not make contact with the base plate. The carrier plate for epitaxial wafer growth is simple in structure, can prevent the epitaxial wafer from making contact with the tray when the epitaxial wafer warps downwards on the basis of ensuring that the epitaxial wafer is stably placed, avoids quality defects such as white spots, scratches or redundant polycrystalline coatings caused by contact with the tray, ensures the back surface quality, and improves the product percent of pass.

Description

Technical Field

[0001] This application belongs to the technical field of epitaxial wafer growth, and particularly relates to a carrier for epitaxial wafer growth and an epitaxial device provided with the carrier. Background Art

[0002] When growing a silicon carbide epitaxial wafer, the epitaxial wafer needs to be placed in a graphite ring. However, due to the problem of structural design, during the growth process of the epitaxial wafer, it is prone to be affected by compressive stress and warp downward, causing the lower end surface of the epitaxial wafer, that is, its back surface, to directly contact the tray. As a result, scratches are likely to appear on the back surface of the epitaxial wafer, as well as white spots a and white atomization b as shown in Figure 4 After directly contacting the tray, the polycrystalline substances generated by the oxidation of the graphite tray will adhere to the back surface of the epitaxial wafer, resulting in a defect of having an excessive polycrystalline coating c as shown in Figure 5 These quality defects directly affect the device performance, resulting in a reduction in the product qualification rate. Summary of the Invention

[0003] This application provides a carrier for epitaxial wafer growth and an epitaxial device provided with the carrier, and solves the technical problem that in the prior art, the epitaxial wafer is prone to contact the tray due to warping under compressive stress during the growth process.

[0004] To solve at least one of the above technical problems, the technical solution adopted in this application is:

[0005] A carrier for epitaxial wafer growth includes a ring frame and a chassis. A ring platform extending towards the center side is constructed inside the ring frame. The epitaxial wafer is placed on the upper end surface of the ring platform, and the chassis is placed below the ring platform; the ring platform can support the downwardly warped epitaxial wafer during epitaxial wafer growth and ensure that its maximum deformation position does not contact the chassis.

[0006] Further, the ring platform is horizontally configured inside the ring frame.

[0007] Further, the ring platform divides the ring frame into an upper cavity and a lower cavity that communicate with each other. The chassis is embedded in the lower cavity and is detachably engaged with the ring frame.

[0008] Further, the wall thickness of the upper cavity is greater than that of the lower cavity, and the inner diameter of the lower cavity is adapted to the diameter of the chassis.

[0009] Further, the inner diameter of the upper cavity is 20 - 200 um larger than the diameter of the epitaxial wafer.

[0010] Further, the height of the ring platform is greater than the maximum downward warping deformation amount of the epitaxial wafer.

[0011] Further, the circumferential diameter width of the upper end surface of the ring platform is 1000 - 1500 um.

[0012] Further, the upper end surface of the upper cavity is configured as an inverted conical frustum surface with an inclination angle of 30-60°.

[0013] Further, the depth of the upper cavity is greater than the thickness of the epitaxial wafer and is configured to be 350-700 um.

[0014] An epitaxial device is provided with the carrier plate as described above.

[0015] Using the carrier plate for epitaxial wafer growth designed in this application, on the basis of ensuring the stable placement of the epitaxial wafer, it can prevent the epitaxial wafer from coming into contact with the tray when warping downward, avoid quality defects such as white spots, scratches, or excessive polycrystalline coatings caused by contact with the tray, ensure the back quality, and improve the product qualification rate. This application also proposes an epitaxial device provided with this carrier plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of a carrier plate for epitaxial wafer growth in this application;

[0017] Figure 2 is a schematic diagram of the relative position of the epitaxial wafer when warping downward with respect to the chassis in this application;

[0018] Figure 3 is a cross-sectional view of the single-sided ring frame in this application;

[0019] Figure 4 is an epitaxial wafer with white spots and white atomization defects;

[0020] Figure 5 is an epitaxial wafer with excessive polycrystalline coating defects;

[0021] Figure 6 is a defect-free epitaxial wafer grown using the carrier plate of this application.

[0022] In the figure:

[0023] 10. Ring frame 11. Ring platform 12. Upper cavity

[0024] 13. Lower cavity 14. Ring table surface 20. Chassis

[0025] 30. Epitaxial wafer 40. Strong light lamp a. White spot

[0026] b. White atomization c. Polycrystalline coating A. Position point

[0027] B. Area C. Inclined surface DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] This embodiment provides a carrier for epitaxial wafer growth, as Figure 1 shown, which includes a ring frame 10 and a chassis 20 that are detachably and cooperatively arranged. An annular platform 11 extending towards the center side is constructed inside the ring frame 20. The annular platform 11 can divide the inner cavity of the ring frame 10 into an upper cavity 12 and a lower cavity 13 that communicate with each other. The epitaxial wafer 30 is placed on the upper cavity 12 and on the upper end surface of the annular platform 11, and the chassis 20 is embedded in the lower cavity 13 below the annular platform and is placed close to the inner wall of the lower cavity 12.

[0030] As Figure 2 shown, the annular platform 11 can support the downwardly warped epitaxial wafer 30 during the growth of the epitaxial wafer 30 and make its maximum deformation position not contact the surface of the chassis 20. This structure allows the epitaxial wafer to grow in a growth atmosphere without any obstruction, and the downwardly warped surface of the epitaxial wafer is suspended above the chassis 20 and its lowest position point C does not directly contact the chassis 20. This can not only avoid controlling the rotation of the chassis 20 during growth and prevent friction with the lower bottom surface of the epitaxial wafer, thus preventing problems such as white spots, scratches, or white atomization on the lower end surface of the epitaxial wafer; but also avoid the deposition of reaction gas in the cavity on the lower end surface (i.e., the back surface) of the epitaxial wafer and prevent problems such as white etching atomization or polycrystalline coating adhesion on the back surface.

[0031] As Figure 3 shown, the annular platform 11 is horizontally configured inside the ring frame 10, and the width of its inward horizontal extension, that is, the ring diameter width L1 of its upper end surface, is 1000 - 1500 um. The width of the surface is such that at least it is ensured that the epitaxial wafer can be completely and stably placed on this platform surface.

[0032] Furthermore, the height H1 of the annular platform 11 needs to be greater than the maximum deformation amount of the epitaxial wafer warping downward. The purpose is to ensure that under the influence of the growth pressure, the maximum height deformation amount of the epitaxial wafer warping downward is less than the height of the annular platform 11, that is, as Figure 2 the position point C in does not contact the upper end surface of the chassis 20 during the entire growth process, so that white spots will not be generated on its back surface. Preferably, the height H1 of the annular platform 11 is 500 - 1500 um, which can keep the position point C of the epitaxial wafer warping downward at a certain height and not contact the chassis 20.

[0033] In this embodiment, since the upper cavity 12 is mainly used to support the placement of the epitaxial wafer 30, it is necessary for it to have sufficient thickness to improve its overall strength. At the same time, the inner diameter of the lower cavity 13 is adapted to the diameter of the chassis 20 and is in close contact. The setting of the chassis 20 can not only rotate during the growth process, but also drive the ring frame 10 carrying the epitaxial wafer to rotate together, making the growth of the epitaxial wafer more uniform. The chassis 20 can also be used as a support to enhance the top support of the lower cavity 13 and improve its anti-deformation ability. Furthermore, in the ring frame 10, the wall thickness of the upper cavity 12 is greater than that of the lower cavity 13.

[0034] In addition, the close fit between the chassis 20 and the lower cavity 13 can prevent the reaction gas from penetrating into the area B on the back of the epitaxial wafer 30. Even if a silicon carbide polycrystalline layer grows on the upper surface of the chassis 20, due to the gap space in the area B, the back surface cannot be adhered with the silicon carbide polycrystalline layer on the upper surface of the chassis 20, that is, no redundant silicon carbide polycrystalline coating can be formed on the back surface.

[0035] Furthermore, the inner diameter of the upper cavity 12 is 20 - 200 um larger than the diameter of the epitaxial wafer 30, so that when the epitaxial wafer 30 is placed on the upper end surface of the ring platform 11, it will not interfere with the inner wall of the upper cavity 12. At the same time, this size difference should not be too large to avoid the problem that the epitaxial wafer collides with the upper cavity 12 during rotation.

[0036] Furthermore, the upper end surface of the upper cavity 12 is configured as an inverted conical frustum surface, with its major diameter surface at the uppermost end and diffusing outward, and its minor diameter surface is arranged downward. Preferably, the inclination angle of this frustum surface is 30 - 60°, aiming to facilitate the normal placement and picking of the suction pen. Since the downward warping amplitude of the epitaxial wafer 30 is relatively large, the reaction gas can penetrate from the inclined surface A in Figure 2 to the gap between the back surface and the chassis 20. The existing structure makes there be a gap between the position point C at the lower end surface of the epitaxial wafer and the chassis 20, so that the temperature and environment of the back surface are consistent, and thus it is not easy to form the silicon carbide polycrystalline coating as described above in the back surface area B, that is, the defect shown in Figure 5 will not occur.

[0037] In the upper cavity 12, the height H2 excluding the height of this frustum surface ranges from 200 to 300 um; its height can be greater than the thickness of the epitaxial wafer or less than the thickness of the epitaxial wafer, and it is not specifically limited here. As long as it can be ensured that when the epitaxial wafer is placed therein, the height of the epitaxial wafer does not exceed the height H3 of the entire upper cavity 12.

[0038] Furthermore, the depth H3 of the upper cavity 12 is greater than the thickness of the epitaxial wafer 30. Preferably, the depth H3 is configured as 350 - 700 um; to ensure that the wafer does not protrude from the upper cavity 12 and ensure that the gas flow field is not disturbed during the growth process.

[0039] In the prior art, on the surface of the epitaxial wafer 30 processed with the existing carrier structure, under the irradiation of the strong light lamp 40, there are defects such as the white spots a and the white atomization b pointed out in Figure 4 , or there are defects such as the redundant polycrystalline coating c pointed out in Figure 5 .

[0040] For the carrier structure designed by the present application, it not only does not affect the overall temperature field and flow field, but also no influence on the key parameters of the product epitaxy is found during the growth process of the SiC epitaxial wafer 30. Moreover, as shown in Figure 6 , on the surface of the obtained epitaxial wafer 30 under the irradiation of the strong light lamp 40, no quality defects appear. By adopting this structure, there is no need to change the growth conditions or the process flow, and the service lives of the designed ring frame 10 and the chassis 20 are both better than those of the existing structure. Not only is the overall structure simple, but also an epitaxial wafer without any quality defects such as white spots, scratches, or redundant polycrystalline coatings on the surface can be obtained.

[0041] An epitaxial device is provided with the carrier as described above.

[0042] By adopting a carrier for growing an epitaxial wafer designed by the present application, on the basis of ensuring that the epitaxial wafer is placed stably, it can prevent the epitaxial wafer from coming into contact with the tray when it warps downward, avoid quality defects such as white spots, scratches, or redundant polycrystalline coatings caused by contact with the tray, ensure the back quality, and improve the product qualification rate. The present application also proposes an epitaxial device provided with this carrier.

[0043] The above has described the embodiments of the present application in detail. The above content is only the preferred embodiments of the present application and cannot be considered as used to limit the scope of implementation of the present application. All equivalent changes and improvements made according to the scope of the present application should still fall within the scope covered by the patent of the present application.

Claims

1. A carrier for epitaxial wafer growth, characterized in that: It includes a ring frame and a chassis. The inner side of the ring frame is structured with a ring platform extending toward its center side. The epitaxial wafer is mounted on the upper end surface of the ring platform, and the chassis is placed under the ring platform. The ring platform can support the epitaxial wafer that is warped downward during the growth of the epitaxial wafer and prevent its maximum deformation position from contacting the chassis.

2. The epitaxial wafer growth carrier according to claim 1, characterized in that: The ring platform is horizontally arranged inside the ring frame.

3. A carrier for epitaxial wafer growth according to claim 1 or 2, characterized in that: The ring platform divides the ring frame into an upper cavity and a lower cavity which are interconnected, and the bottom plate is embedded in the lower cavity and detachably cooperates with the ring frame.

4. The epitaxial wafer growth carrier according to claim 3, characterized in that: The wall thickness of the upper cavity is greater than that of the lower cavity, and the inner diameter of the lower cavity is matched with the diameter of the chassis.

5. The epitaxial wafer growth carrier according to claim 4, characterized in that: The inner diameter of the upper cavity is 20-200um larger than the diameter of the epitaxial wafer.

6. A carrier for epitaxial wafer growth according to any one of claims 4 to 5, characterized in that: The height of the ring platform is greater than the maximum deformation of the epitaxial wafer warping downward.

7. The epitaxial wafer growth carrier according to claim 6, characterized in that: The ring diameter width of the upper end surface of the ring platform is 1000-1500um.

8. A carrier for epitaxial wafer growth according to any one of claims 4 to 5 and 7, characterized in that: The upper end surface of the upper cavity is constructed as an inverted cone table surface, and its inclination angle is 30-60 degrees.

9. The epitaxial wafer growth carrier according to claim 8, characterized in that: The upper cavity depth is greater than the epitaxial wafer thickness and is configured to be 350-700um.

10. An epitaxial device, characterized in that: A carrier plate as described in any one of claims 1 to 9 is provided.

Images