Graphite disc and ring for epitaxial growth of silicon carbide

Abstract

The invention provides a graphite plate and a graphite ring for epitaxial growth of silicon carbide, and relates to the technical field, the graphite plate and the graphite ring for epitaxial growth of silicon carbide comprise a graphite plate and a graphite ring, and the graphite plate and the graphite ring comprise a graphite plate front surface and a wafer back surface; a groove is formed in the front surface of the graphite plate, and the groove is circular; a preset matching position of the ring is obtained, a protrusion is arranged at the preset matching position, and the protrusion is circular; by changing the structures of the graphite disc and the ring, the probability that source gas enters the back surface of the wafer is reduced, and the problems of atomization, black spots, marks and the like on the back surface of the epitaxial wafer are fundamentally solved.

Description

Technical Field

[0001] The invention provides a graphite disk and a ring for epitaxial growth of silicon carbide, and relates to the technical field of semiconductor technology, in particular to the technical field of stone grinding disks and rings for epitaxial growth of silicon carbide. Background Art

[0002] The third generation semiconductor silicon carbide (SiC) has attracted much attention in the semiconductor industry. It has excellent properties such as high breakdown field strength, high saturated electron drift rate, high thermal conductivity, and high chemical stability. It is an ideal material for making high-temperature, high-frequency, high-voltage, high-power and radiation-resistant new power semiconductor devices. It has important application potential in electric vehicles, rail transportation, high-voltage power transmission and transformation, photovoltaics, 5G communications and other fields. Among them, silicon carbide epitaxy is an important part of the entire process. The epitaxial process can grow a new single crystal layer and accurately control the thickness and impurity doping concentration of the epitaxial layer. The new epitaxial layer can reduce the defects on the substrate to meet the preparation requirements of power devices.

[0003] The monolithic horizontal hot wall chamber is one of the most common chambers for homogeneous epitaxy of silicon carbide. It uses induction heating to heat the graphite base of the chamber, and an external graphite felt is used for insulation. The reaction source gas enters the chamber from one side of the chamber, and the wafer substrate is placed on the graphite disk in the chamber for epitaxial growth. At present, the silicon carbide epitaxial process is generally around 1600℃. At such a high temperature, the wafer substrate undergoes a certain deformation, causing the source gas to react and deposit on the back of the wafer. Therefore, some abnormal conditions will appear on the back of the wafer, such as atomization, black spots, and marks on the back of the wafer. The abnormal conditions lead to poor appearance of the epitaxial wafer and will have an adverse effect on the manufacturing process of the device end. As the market demand for silicon carbide power devices continues to rise, more stringent requirements are also placed on its quality. The graphite disks and rings currently in use have begun to show disadvantages in the process of mass production of silicon carbide epitaxial wafers. The industry urgently needs to design a new structure of graphite disks and rings to solve the abnormal conditions on the back of the epitaxial wafer. Summary of the invention

[0004] The present invention provides a graphite disk and ring for epitaxial growth of silicon carbide to solve the above problems:

[0005] The present invention provides a graphite disk and ring for epitaxial growth of silicon carbide, wherein the graphite disk and ring for epitaxial growth of silicon carbide include a graphite disk and a ring, wherein the graphite disk and the ring include a front surface of the graphite disk and a back surface of a wafer;

[0006] The front side of the graphite disk is provided with a groove 12, and the groove 12 is circular;

[0007] Obtaining a preset matching position of the ring, wherein a protrusion 21 is provided at the preset matching position, and the protrusion 21 is circular;

[0008] The protrusion 21 matches the groove 12 .

[0009] Furthermore, the groove 12 has a width of 0.1 to 3 mm and a depth of 0.1 to 1 mm.

[0010] Furthermore, a chamfer is provided at the edge 13 of the front side of the graphite disk, and a partial compensation 23 is provided between the chamfer and the ring.

[0011] Furthermore, the graphite ring step 22 has a height variation.

[0012] Furthermore, the setting method includes:

[0013] Setting the front side of the graphite disk and the back side of the wafer;

[0014] A groove 12 is provided on the front side of the graphite disk, and the groove 12 is circular;

[0015] Obtaining a preset matching position of the ring, and setting a protrusion 21 at the preset matching position, wherein the protrusion 21 is circular;

[0016] The protrusion 21 is matched with the groove 12 to obtain a matching result.

[0017] Further, the width of the groove 12 is set to 0.1 to 3 mm, and the depth is set to 0.1 to 1 mm.

[0018] Furthermore, a chamfer is provided at the edge 13 of the front side of the graphite disk, and the chamfer is partially compensated 23 with the ring.

[0019] Furthermore, the height of the graphite ring step 22 is increased.

[0020] Beneficial effects of the present invention: The present invention proposes a graphite disk and a graphite ring with a new structure, which can reduce the probability of fogging, black spots, marks, etc. on the back of the wafer without affecting the parameters of the epitaxial wafer. Since the back of the silicon carbide epitaxial wafer made of the current graphite disk and ring has abnormal conditions such as fogging, black spots, marks, etc., this paper proposes a new graphite disk and ring structure to improve the above abnormalities; the above reasons are analyzed as follows: 1. The epitaxial process is carried out at 1600°C, and the wafer has a certain warping at high temperature. The source gas enters the back of the wafer from the warping and reacts and deposits, resulting in fogging; 2. The graphite ring is designed to be thin, with low strength, and is coated with SiC coating. At high temperature and with cumulative use, the deformation of the graphite ring will change, and the source gas enters the back of the wafer through the deformation and deposits, resulting in fogging. Compared with the prior art, the structure of the graphite disk and ring for SiC epitaxy provided by the present invention has changed. First, a groove is provided on the front edge of the graphite disk, and the groove is circular. The ring is provided with a protrusion at a corresponding matching position, and the protrusion is also circular and matches the groove of the graphite disk. The front edge of the graphite disk is chamfered to a large extent, and the chamfered part is compensated to the ring to increase the structural stability of the graphite ring. The graphite disk and ring for SiC epitaxy provided by the present invention can reduce the probability of source gas entering the back side of the wafer through the groove provided on the graphite disk and the protrusion on the ring, as well as the height of the graphite ring step, thereby inhibiting the occurrence of deposition on the back side of the wafer, fundamentally solving the abnormal conditions such as atomization, black spots, marks, etc. on the back side of the wafer, and ultimately improving the yield of silicon carbide epitaxial wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a front view of a graphite disk;

[0022] Figure 2 This is a schematic diagram of the back side of the graphite ring;

[0023] Figure 3 This is a schematic diagram of the actual cross-section of the new structure graphite disk and graphite ring. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0025] One embodiment of the present invention provides a graphite disk and ring for epitaxial growth of silicon carbide, wherein the graphite disk and ring for epitaxial growth of silicon carbide include a graphite disk and a ring, wherein the graphite disk and the ring include a front surface of the graphite disk and a back surface of a wafer;

[0026] The front side of the graphite disk is provided with a groove 12, and the groove 12 is circular;

[0027] Obtaining a preset matching position of the ring, wherein a protrusion 21 is provided at the preset matching position, and the protrusion 21 is circular;

[0028] The protrusion 21 matches the groove 12 .

[0029] The working principle and technical effect of the above technical scheme are as follows: a groove 12 is opened on the front edge of the graphite disk, and the groove is circular. A protrusion 21 is opened at the corresponding matching position of the ring, and the protrusion is also circular and matches the groove of the graphite disk, wherein the groove width is 0.1-3mm and the depth is 0.1-1mm; this part is used to block the source gas entering the back of the wafer due to the graphite ring deformation; the front edge of the graphite disk has a large chamfer treatment such as 13, and the chamfered part is compensated to the ring such as 23; this part is used to increase the structural stability of the graphite ring; the step height of the graphite ring 22 is increased; this part is used to prevent the wafer from deforming at high temperature and the source gas from entering the back for reaction deposition; the present invention can reduce the probability of atomization, black spots, marks, etc. on the back of the wafer without affecting the parameters of the epitaxial wafer. Since the back of the silicon carbide epitaxial wafer made of the current graphite disk and ring has abnormal conditions such as fogging, black spots, and marks, this paper proposes a new graphite disk and ring structure to improve the above abnormalities; the above reasons are analyzed as follows: 1. The epitaxial process is carried out at 1600℃, and the wafer has a certain warping at high temperature. The source gas enters the back of the wafer from the warping and reacts and deposits, resulting in fogging; 2. The graphite ring is designed to be thin, with low strength, and is coated with SiC coating. At high temperature and with cumulative use, the deformation of the graphite ring will change, and the source gas enters the back of the wafer through the deformation and deposits, resulting in fogging. Compared with the prior art, the structure of the graphite disk and ring for SiC epitaxy provided by the present invention has changed. First, a groove is provided on the front edge of the graphite disk, and the groove is circular. The ring is provided with a protrusion at a corresponding matching position, and the protrusion is also circular and matches the groove of the graphite disk. The front edge of the graphite disk is chamfered to a large extent, and the chamfered part is compensated to the ring to increase the structural stability of the graphite ring. The graphite disk and ring for SiC epitaxy provided by the present invention can reduce the probability of source gas entering the back side of the wafer through the groove provided on the graphite disk and the protrusion on the ring, as well as the height of the graphite ring step, thereby inhibiting the occurrence of deposition on the back side of the wafer, fundamentally solving the abnormal conditions such as atomization, black spots, marks, etc. on the back side of the wafer, and ultimately improving the yield of silicon carbide epitaxial wafers.

[0030] In one embodiment of the present invention, the groove 12 has a width of 0.1 to 3 mm and a depth of 0.1 to 1 mm. This portion is used to block the source gas that enters the back side of the wafer due to the graphite annular deformation.

[0031] The working principle and technical effect of the above technical solution are as follows: during the epitaxial growth of silicon carbide, source gas (such as silicon source gas and carbon source gas) enters the space between the graphite disk and the wafer through the reaction chamber. The width and depth of the groove 12 are reasonably designed, which can effectively block the source gas that may leak into the back of the wafer due to the deformation of the graphite ring. When the graphite ring is deformed due to heat or other factors, the matching structure of the protrusion 21 and the groove 12 can maintain a certain degree of sealing to prevent the leakage of the source gas. The setting of the groove 12 is not only used to block the source gas, but also to maintain the stability of the wafer to a certain extent. The wafer needs to be kept flat and stable during the growth process to ensure the uniformity of the epitaxial layer. The groove 12 provides a stable support surface for the wafer through its structural characteristics, which can reduce the shaking and displacement of the wafer during the growth process. The design of the groove 12 is an important optimization point in the epitaxial growth process of silicon carbide. By adjusting parameters such as the width and depth of the groove, the back of the wafer can be further optimized and the yield of the epitaxial wafer can be improved. The design of the groove 12 in the graphite disk having a width of 0.1 to 3 mm and a depth of 0.1 to 1 mm plays a key role in the epitaxial growth process of silicon carbide, which can effectively prevent the leakage of source gas and maintain the stability of the wafer.

[0032] In one embodiment of the present invention, the edge 13 of the front side of the graphite disk is provided with a chamfer, and the chamfer and the ring are partially compensated 23. This portion is used to increase the structural stability of the graphite ring.

[0033] The working principle and technical effect of the above technical solution are as follows: the chamfer design forms a structural complement between the edge of the graphite disk and the graphite ring. When the graphite ring is deformed due to heat or other factors, the chamfered part can act as a "buffer zone" to absorb part of the deformation stress, thereby reducing the direct impact on the main structure of the graphite disk. The presence of the chamfer increases the contact area between the graphite disk and the graphite ring. A larger contact area means stronger bonding and better stability, which helps prevent the graphite ring from falling off or being damaged due to stress concentration during the growth process. The chamfer design also helps to disperse the stress distribution at the junction of the graphite disk and the graphite ring. During the epitaxial growth of silicon carbide, the graphite disk and the graphite ring are subjected to high temperature and source gas pressure, which may cause stress concentration at the junction. The presence of the chamfer can disperse these stresses over a larger area, thereby reducing the risk of stress concentration. By increasing the chamfer of the edge of the graphite disk and partially compensating with the graphite ring, the structural stability of the graphite ring during the epitaxial growth of silicon carbide is significantly improved. This helps to ensure that the graphite ring can withstand the effects of high temperature and source gas pressure for a long time without being damaged. The chamfer design can reduce the direct impact of the graphite ring deformation on the main structure of the graphite disk and increase the stability of the joint. The chamfer design is an important optimization point in the silicon carbide epitaxial growth process. There is a design of partial compensation 23 between the chamfer set at the edge 13 of the front side of the graphite disk and the graphite ring.

[0034] In one embodiment of the present invention, the graphite ring step 22 has a height change, and the height change includes a height increase. This part is used to prevent the wafer from deforming at high temperature, and the source gas enters the back side for reaction deposition;

[0035] The working principle and technical effect of the above technical solution are as follows: the increase in the height of the graphite ring step 22 provides a more stable support surface for the wafer. In a high temperature environment, the wafer may be deformed due to thermal expansion, and the step with increased height can block the source gas from entering the back of the wafer from the wafer inflection point, ensuring its stability during the growth process. If the back of the wafer is exposed to the source gas, it may cause unexpected chemical reactions and deposition, affecting the quality and uniformity of the epitaxial layer. The height change design of the graphite ring step 22, especially its increased part, forms a physical barrier that effectively blocks the source gas from penetrating from the edge of the wafer to the back. In the process of silicon carbide epitaxial growth, the uniform distribution of the source gas is crucial to obtain high-quality epitaxial layers. The height change of the graphite ring step 22 can affect the distribution of the gas flow in the reaction chamber, and by optimizing the gas flow path, it ensures that the source gas can reach the wafer surface more evenly, reducing the negative impact of uneven gas flow on the back of the wafer. The height increase of the graphite ring step 22 is significantly increased to block the source gas from entering the back of the wafer from the wafer inflection point. By forming a physical barrier, the source gas is effectively prevented from penetrating to the back of the wafer, avoiding unexpected chemical reactions and deposition, and ensuring the purity and uniformity of the epitaxial layer. The height variation of the graphite ring step 22 optimizes the gas flow distribution, provides more ideal conditions for the epitaxial growth of silicon carbide, and helps to improve the growth rate and crystal quality of the epitaxial layer. By reducing problems such as wafer deformation and back-side reaction deposition, the stability and controllability of the epitaxial growth process are improved.

[0036] In one embodiment of the present invention, the setting method includes:

[0037] Setting the front side of the graphite disk and the back side of the wafer;

[0038] A groove 12 is provided on the front side of the graphite disk, and the groove 12 is circular;

[0039] Obtaining a preset matching position of the ring, and setting a protrusion 21 at the preset matching position, wherein the protrusion 21 is circular;

[0040] The protrusion 21 is matched with the groove 12 to obtain a matching result.

[0041] The width of the groove 12 is set to 0.1 to 3 mm, and the depth is set to 0.1 to 1 mm. This portion is used to block the source gas that enters the back side of the wafer due to the graphite annular shape.

[0042] A chamfer is provided at the edge 13 of the front side of the graphite disk, and the chamfer is partially compensated with the ring 23. This part is used to increase the structural stability of the graphite ring.

[0043] The height of the graphite ring step 22 is increased, and the height change includes a height increase. This part is used to prevent the wafer from deforming at high temperature, and the source gas enters the back side for reaction deposition;

[0044] The working principle and technical effect of the above technical scheme are as follows: the setting method of the graphite disk and ring for SiC epitaxy provided by the present invention has changed. First, a groove is opened on the front edge of the graphite disk, and the groove is circular. The ring is opened at the corresponding matching position with a protrusion, which is also circular and matches the groove of the graphite disk; the front edge of the graphite disk has a large chamfer treatment, and the chamfered part is compensated to the ring to increase the structural stability of the graphite ring. The graphite disk and ring for silicon carbide epitaxy provided by the present invention can reduce the probability of source gas entering the back side of the wafer through the groove opened on the graphite disk and the protrusion on the ring, as well as the height of the graphite ring step, thereby inhibiting the occurrence of deposition on the back side of the wafer, fundamentally solving the abnormal conditions such as atomization, black spots, marks, etc. on the back side of the wafer, and ultimately improving the yield of silicon carbide epitaxial wafers; the matching structure of the groove 12 and the protrusion 21 forms an effective sealing barrier, which can block the source gas that may enter the back side of the wafer due to the deformation of the graphite ring, thereby ensuring the stability and controllability of the epitaxial growth process. The chamfer of the edge of the graphite disk combined with the partial compensation 23 structure of the graphite ring strengthens the bonding force between the graphite ring and the graphite disk, improves the structural stability of the graphite ring, and reduces the risk of damage caused by stress concentration. The purpose of the new structure is to improve the back side of the wafer, optimize the appearance of the epitaxial wafer, and improve the yield of the epitaxial wafer.

[0045] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A graphite disk and ring for epitaxial growth of silicon carbide, characterized in that: The graphite disk and ring for epitaxial growth of silicon carbide include a graphite disk and a ring, wherein the graphite disk and the ring include a front surface of the graphite disk and a back surface of a wafer; The front side of the graphite disk is provided with a groove, and the groove is circular; Acquire a preset matching position of the ring, wherein a protrusion is provided at the preset matching position, and the protrusion is circular; The protrusion matches the groove.

2. A graphite disk and ring for epitaxial growth of silicon carbide according to claim 1, characterized in that: The groove has a width of 0.1 to 3 mm and a depth of 0.1 to 1 mm.

3. A graphite disk and ring for epitaxial growth of silicon carbide according to claim 1, characterized in that: A chamfer is arranged at the edge of the front side of the graphite disk, and the chamfer is partially compensated with the ring.

4. A graphite disk and ring for epitaxial growth of silicon carbide according to claim 1, characterized in that: The graphite ring steps vary in height.

5. A method for implementing the arrangement of graphite disks and rings for epitaxial growth of silicon carbide as claimed in claim 1, characterized in that: The setting method comprises: Setting the front side of the graphite disk and the back side of the wafer; A groove is arranged on the front side of the graphite disk, and the groove is circular; Obtaining a preset matching position of the ring, and setting a protrusion at the preset matching position, wherein the protrusion is circular; Match the protrusions with the grooves to obtain a matching result.

6. The method for setting graphite disks and rings for epitaxial growth of silicon carbide according to claim 5, characterized in that: The width of the groove is set to 0.1 to 3 mm, and the depth is set to 0.1 to 1 mm.

7. The method for setting graphite disks and rings for epitaxial growth of silicon carbide according to claim 5, characterized in that: A chamfer is provided at the edge of the front side of the graphite disk, and the chamfer is partially compensated with the ring.

8. The method for setting graphite disks and rings for epitaxial growth of silicon carbide according to claim 5, characterized in that: Increase the height of the graphite ring step.

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