Bearing disc assembly and extension equipment

Abstract

The utility model provides a bearing disc assembly and epitaxial equipment, the bearing disc assembly comprises a bearing disc and a cover ring, a first surface of the bearing disc comprises a groove area and an edge area surrounding the groove area, the groove area is formed by recessing the first surface of the bearing disc towards a second surface of the bearing disc by a first depth, and the groove area comprises a wafer placing area. The cover ring covers the bearing disc and comprises a body part and a protruding part, the body part covers the edge area, the protruding part is connected with the body part, protrudes towards one side close to the groove area and is suspended above the groove area, and the orthographic projection of the protruding part on the bearing disc and the wafer placing area have an overlapping part. After the cover ring covers the bearing disc, the protruding part of the cover ring is located above the wafer, a cover plate structure is formed, the gap between the lower surface of the protruding part and the upper surface of the wafer is reduced, gas is made difficult to enter the gap between the wafer and the side wall of the groove area, the gas is prevented from entering the back face of the wafer, and white spots on the back face of the epitaxial wafer are prevented from being formed.

Description

Technical Field

[0001] This application relates to the field of semiconductor fabrication technology, and in particular to a carrier disk assembly and epitaxial device. Background Technology

[0002] Chemical vapor deposition (CVD) is the most commonly used method for obtaining silicon carbide epitaxy. Currently, in the CVD process for growing silicon carbide epitaxial layers, the silicon carbide wafer is supported and fixed using a corresponding carrier pad. Due to the incomplete contact between the back side of the silicon carbide wafer (the non-epitaxial growth surface) and the graphite pad surface, gas can enter the back side of the silicon carbide wafer through the gaps between the graphite ring and the wafer edge during epitaxial growth, causing uneven etching of the back side. Simultaneously, carbon and silicon source gases may also enter the back side along with the carrier gas, forming polycrystalline lumps that unevenly cover the back side. This gas intrusion results in a "fog-like" appearance on the back side of the silicon carbide epitaxial wafer, a phenomenon known in the industry as "white spots." For thick-film epitaxial wafers, with increasing epitaxial growth time, the uneven etching and polycrystalline growth phenomena on the back side become more pronounced, and the "white spot" phenomenon becomes more obvious. Removing the white spots on the back side increases processing steps, production costs, and production efficiency, and also leads to a decrease in product yield. Utility Model Content

[0003] The purpose of this application is to provide a carrier disk assembly and epitaxial device to solve the problem of "white spots" easily appearing on the back side of silicon carbide substrate epitaxial wafers. The specific technical solution is as follows:

[0004] This application provides a carrier disk assembly, comprising: a carrier disk, a first surface of which includes a recessed area and an edge area surrounding the recessed area, the recessed area being formed by the first surface of the carrier disk being recessed into a second surface of the carrier disk to a first depth, the recessed area including a wafer placement area; and a cover ring, which covers the carrier disk, the cover ring including a body portion and a protrusion portion, the body portion covering the edge area, the protrusion portion being connected to the body portion and protruding towards a side close to the recessed area, and suspended above the recessed area, the protrusion portion having an overlapping portion with the wafer placement area in the orthographic projection of the carrier disk.

[0005] In some embodiments, the protrusion includes a first portion and a second portion, wherein the second portion is a portion recessed into the groove area.

[0006] In some embodiments, the thickness of the second portion is 0.1 mm to 0.3 mm.

[0007] In some embodiments, there is a gap between the lower surface of the second portion and the upper surface of the wafer in the wafer placement area, the gap being 0.1 mm to 0.2 mm.

[0008] In some embodiments, the inner side of the protrusion includes an annular surface and a conical surface, the conical surface being located on the side of the annular surface closer to the wafer, and the diameter of the conical surface gradually increasing along the direction closer to the wafer, for the purpose of avoiding the upper surface of the wafer.

[0009] In some embodiments, the diameter of the base of the tapered surface is equal to the diameter of the wafer.

[0010] In some embodiments, the width of the overlapping portion of the protrusion on the carrier disk and the wafer carrier area is 0.3 mm to 1.0 mm.

[0011] In some embodiments, the upper surface of the cover ring is inclined, and along the direction close to the groove area, the upper surface of the cover ring gradually moves away from the first surface of the support plate.

[0012] In some embodiments, the inclination angle of the inclined plane is 2° to 5°.

[0013] In some embodiments, a first positioning portion is provided on the inner side of the protrusion, and the side of the first positioning portion facing the groove area is a plane.

[0014] A second aspect of this application provides an epitaxial device, the epitaxial device including the carrier disk assembly described above.

[0015] Beneficial effects of the embodiments in this application:

[0016] The carrier disk assembly and epitaxial growth apparatus provided in this application include a carrier disk and a cover ring. After the cover ring is fitted onto the carrier disk, the protrusion of the cover ring is located above the wafer, forming a cover plate structure. This reduces the gap between the lower surface of the protrusion and the upper surface of the wafer, making it difficult for gas to enter the gap between the wafer and the sidewall of the recessed area, thereby preventing gas from entering the back side of the wafer. Therefore, epitaxial growth using this carrier disk assembly can avoid the formation of "white spots" on the back side of the SiC epitaxial wafer. Furthermore, epitaxial growth using this carrier disk assembly can also reduce the amount of gas entering the gap between the cover ring and the carrier disk, effectively suppressing the formation of SiC particles on the sidewall of the carrier disk, and avoiding carding or cracking during the epitaxial growth process due to the accumulation of a large number of SiC particles on the sidewall of the carrier disk.

[0017] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0019] Figure 1 A plan view of the carrier disk assembly provided in an embodiment of this application;

[0020] Figure 2 for Figure 1 Top view of the central support plate assembly;

[0021] Figure 3 for Figure 2 Exploded view of the central support plate assembly from a top-down perspective;

[0022] Figure 4 for Figure 2 Exploded view of the central support plate assembly from a bottom-up perspective;

[0023] Figure 5 for Figure 1 Cross-sectional view of the central bearing plate assembly;

[0024] Figure 6 This is a simulation diagram of the gas flow rate on the back side of the wafer during epitaxial growth of the carrier disk assembly according to the embodiments of this application;

[0025] Figure 7 This is a simulation diagram illustrating the gas flow rate on the back side of a wafer during epitaxial growth using a conventional carrier disk assembly.

[0026] Figure 8 for Figure 5 A partial view of the left side of the central bearing disk assembly.

[0027] The reference numerals in the attached figures are as follows: carrier disk 1; first surface 11; groove area 111; wafer placement area 1111; overlapping portion 1111a; edge area 112; second positioning portion 1121; second surface 12; cover ring 2; body portion 21; protrusion portion 22; first portion 221; second portion 222; inner side 223; annular surface 2231; conical surface 2232; first positioning portion 2233; upper surface 23 of the cover ring; gap S; tilt angle α; included angle β; wafer 3; positioning edge 31. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0029] Silicon carbide, as a third-generation semiconductor material, possesses advantages such as high thermal conductivity, high breakdown field strength, high saturated electron drift velocity, and high bonding energy. It can well meet the application requirements of modern electronic technology under harsh conditions such as high temperature, high power, high voltage, high frequency, and high radiation, and plays an important role in next-generation high-voltage power electronic semiconductor devices. Silicon carbide devices are formed on silicon carbide epitaxial wafers through a series of processes. The silicon carbide epitaxial wafer plays an indispensable role. However, in existing technologies, "white spots" easily appear on the back side of the silicon carbide epitaxial wafer during growth. Removing these white spots increases processing steps, production costs, and reduces production efficiency, and also leads to a decrease in product yield. To solve the above problems, the first aspect of this application provides a carrier disk assembly. This carrier disk assembly has a simple structure, is easy to operate, and improves the white spot problem on the back side of the epitaxial wafer while reducing costs and increasing efficiency.

[0030] Specifically, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, Figure 1 This is a plan view of the carrier disk assembly provided in an embodiment of this application. Figure 2 for Figure 1 Top view of the central support plate assembly. Figure 3 for Figure 2 Exploded view of the central support plate assembly from a top-down perspective. Figure 4 for Figure 2 Exploded view of the central support plate assembly from a low angle. Figure 5 for Figure 1 Cross-sectional view of the central bearing plate assembly.

[0031] The carrier tray assembly includes a carrier tray 1 and a cover ring 2. The first surface 11 of the carrier tray 1 includes a recessed area 111 and an edge area 112 surrounding the recessed area 111. The recessed area 111 is formed by the first surface 11 of the carrier tray 1 being recessed to a first depth into the second surface 12 of the carrier tray 1. The recessed area 111 includes a wafer placement area 1111. The volume of the recessed area 111 is larger than the volume of the wafer 3 in the wafer placement area 1111. This means that after the wafer 3 is placed in the recessed area 111, there is a certain gap between the outer edge of the wafer 3 and the peripheral sidewall of the recessed area 111, preventing the wafer edge from rubbing against the sidewall during wafer placement, thereby reducing the risk of defects caused by falling debris and making it easier to pick up and place the wafer 3.

[0032] The cover ring 2 covers the carrier disk 1. The cover ring 2 includes a body portion 21 and a protrusion portion 22. The body portion 21 covers the edge region 112. The protrusion portion 22 is connected to the body portion 21 and protrudes towards the side near the groove region 111, and is suspended above the groove region 111. The projection of the protrusion portion 22 onto the carrier disk 1 overlaps with the wafer placement area 1111 by a portion 1111a.

[0033] After the cover ring 2 is placed on the carrier disk 1, the protrusion 22 of the cover ring 2 is located above the wafer 3, forming a cover plate structure. This reduces the gap S between the lower surface of the protrusion 22 and the upper surface of the wafer 3, making it difficult for gas to enter the gap between the wafer 3 and the sidewall of the recessed area 111, thereby reducing the probability of gas entering the back side of the wafer 3. Therefore, epitaxial growth using this carrier disk assembly can avoid the formation of "white spots" on the back side of the wafer 3. Furthermore, epitaxial growth using this carrier disk assembly can also reduce the amount of gas entering the gap between the cover ring 2 and the carrier disk 1, effectively suppressing the formation of SiC particles on the sidewall of the carrier disk, and avoiding carding or cracking during the epitaxial growth process due to the accumulation of too many SiC particles on the sidewall of the carrier disk 1.

[0034] During epitaxial growth of the carrier disk assembly according to the embodiments of this application, the gas flow rate on the back side of the wafer was simulated. The gas flow rate on the back side of the wafer is as follows: Figure 6 As shown, the horizontal axis represents different locations on the back side of the wafer, with the wafer center marked as point "0" on the horizontal axis, and the vertical axis represents the gas flow velocity. From Figure 6 As can be seen, the gas flow velocity on the back side of the wafer is basically around 0 m / s, indicating that no gas enters the back side of the wafer. Therefore, using the carrier disk assembly of this embodiment for epitaxial growth can effectively improve the phenomenon of "white spots" on the back side of the wafer.

[0035] As a comparative example, the gas flow rate on the back side of the wafer was also simulated when using a conventional carrier disk assembly for epitaxial growth. The gas flow rate on the back side of the wafer is as follows: Figure 7As shown, the horizontal axis represents different positions on the back side of the wafer, with the wafer center marked as point "0" on the horizontal axis, and the vertical axis represents the gas flow velocity. The cover ring and carrier disk of a conventional carrier disk assembly can be an integral or separate structure. The cover ring is generally used to define the position of wafer 3, preventing wafer 3 from moving during gas flow and affecting the uniformity of the epitaxial layer. From... Figure 7 It can be seen that the airflow velocity at the -0.2mm to 0mm range on the back side of the wafer is around 0.0001m / s, indicating the presence of gas, which causes "white spots" to appear on the back side of the wafer.

[0036] Furthermore, during epitaxial growth using this carrier disk assembly, the protrusion 22 of the cover ring 2 acts as a cover plate above the wafer 3, preventing the wafer 3 from being unspinned out of the carrier disk 1 as the carrier disk assembly rotates. This is because when the carrier disk assembly is used in an epitaxial device, it needs to rotate during the epitaxial growth process.

[0037] During use, the placement sequence of the carrier disk assembly is as follows: first place the carrier disk 1, then place the wafer 3 in the groove area 111 of the carrier disk 1, and finally place the cover ring 2. The protrusion 22 of the cover ring 2 is equivalent to a cover plate structure for the wafer 3, reducing the possibility of gas entering the back side of the wafer 3 from the gap between the wafer 3 and the graphite disk, effectively improving the "white spot" phenomenon on the back side.

[0038] As a feasible implementation method, the bearing disk 1 can be a graphite disk and the cover ring 2 can be a graphite ring. Of course, other high-temperature resistant and oxidation-resistant materials can also be the preferred materials for the bearing disk 1 and the cover ring 2.

[0039] In some embodiments of this application, reference is made to Figure 5 and Figure 8 As shown, Figure 8 for Figure 5 A partial view of the left side of the carrier disk assembly. The protrusion 22 includes a first portion 221 and a second portion 222, the second portion 222 being recessed into the groove region 111. Recessing the second portion 222 of the protrusion 22 into the groove region 111 further reduces the distance between the upper surface of the wafer 3 and the lower surface of the second portion 222, thereby further reducing the possibility of gas entering the back side of the wafer 3 and effectively improving the "white spot" phenomenon on the back side of the wafer 3.

[0040] Further, refer to Figure 8 As shown, the thickness of the second part 222 is 0.1mm to 0.3mm, for example, it can be 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, etc.

[0041] In this embodiment, the thickness of the second part 222 is between 0.1mm and 0.3mm. On the one hand, this can further reduce the distance between the upper surface of the wafer 3 and the lower surface of the second part 222, and on the other hand, it will not have a significant impact on the accommodating volume of the groove area 111.

[0042] In some embodiments of this application, reference is made to Figure 8 As shown, there is a gap S between the lower surface of the second part 222 and the upper surface of the wafer 3 of the wafer placement area 1111. The gap S is 0.1mm to 0.2mm, for example, it can be 0.1mm, 0.15mm, 0.2mm, etc.

[0043] In this embodiment, the gap S between the lower surface of the second portion 222 and the upper surface of the wafer 3 is between 0.1 mm and 0.2 mm. This further compresses the gap S while allowing the required thickness of the epitaxial wafer to be deposited on the upper surface of the wafer 3. Furthermore, this gap S also considers preventing the wafer 3 from contacting the lower surface of the second portion 222 during the epitaxial process, thus preventing adhesion between the upper surface of the wafer 3 and the lower surface of the second portion 222.

[0044] In some embodiments of this application, reference is made to Figure 8 As shown, the inner side 223 of the protrusion 22 includes an annular surface 2231 and a conical surface 2232. The conical surface 2232 is located on the side of the annular surface 2231 that is close to the wafer 3, and the diameter of the conical surface 2232 gradually increases along the direction close to the wafer 3. Its function is to prevent the effective growth area at the edge of the wafer 3 from touching the conical surface 2232.

[0045] In this embodiment, the inner side 223 of the protrusion 22 near the wafer 3 is set as a conical surface 2232, so that while the protrusion 22 forms a cover plate structure above the wafer 3, it can not block the edge of the wafer 3. In this way, an epitaxial film can be deposited even at the edge of the wafer 3, reducing the influence of the protrusion 22 on the edge of the wafer 3.

[0046] Optionally, refer to Figure 6 As shown, the diameter of the bottom edge of the conical surface 2232 is equal to the diameter of the wafer 3. In this way, the conical surface 2232 of the inner side 223 of the protrusion 22 completely exposes the upper surface of the wafer 3, so that the upper surface of the wafer 3 can be deposited with an epitaxial film, reducing the influence of the protrusion 22 on the edge position of the substrate wafer 3.

[0047] Of course, the bottom edge of the conical surface 2232 can also be slightly smaller than the diameter of the wafer 3, for example, the difference between the two is less than or equal to 0.3 mm.

[0048] In some embodiments of this application, reference is made to Figure 8As shown, the angle β between the conical surface 2232 and the horizontal plane can be 30° to 60°, for example, 30°, 35°, 40°, 45°, 50°, 55°, 60°, etc. With this angle β of 30° to 60°, when the underlying wafer 3 is exposed, the height of the annular surface 2231 on the inner side 223 of the protrusion 22 can be increased as much as possible, thereby improving the suppression of gas entering the gap between the wafer 3 and the peripheral sidewall of the groove region 111.

[0049] In some embodiments of this application, reference is made to Figure 5 , Figure 8 As shown, the width of the overlapping portion 1111a of the protrusion 22 on the carrier disk 1 and the carrier area of ​​the wafer 3 is 0.3mm to 1.0mm, for example, it can be 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, etc.

[0050] The width of the overlapping portion 1111a of the orthographic projection of the protrusion 22 on the carrier disk 1 and the carrier area of ​​the wafer 3 is the width of the overlapping portion 1111a of the orthographic projection of the protrusion 22 on the carrier disk 1 and the orthographic projection of the wafer 3 on the carrier disk 1. This width is 0.3mm-1mm, so that the cover-like structure formed by the protrusion 22 above the wafer 3 can effectively prevent gas from entering the back side of the wafer 3 from the gap between the wafer 3 and the peripheral sidewall of the recess area 111, thereby effectively improving the "white spot" phenomenon on the back side of the wafer 3.

[0051] In some embodiments of this application, reference is made to Figure 5 , Figure 8 As shown, the upper surface 23 of the cover ring is inclined, and along the direction close to the groove area 111, the upper surface 23 of the cover ring gradually moves away from the first surface 11 of the bearing plate 1.

[0052] In this embodiment, the upper surface 23 of the cover ring is sloped. The sloped structure can change the direction of gas movement, increasing the distance the gas needs to travel to enter the upper surface of the wafer 3. This further suppresses gas from passing through the edge of the wafer 3, effectively improving the "white spot" phenomenon on the back side of the wafer 3. Furthermore, the sloped upper surface 23 of the cover ring can change the direction of gas movement, causing the gas to flow upwards, effectively suppressing downward flow and reducing the amount of gas flowing through the edge of the wafer 3, thus effectively improving the "white spot" phenomenon on the back side of the wafer 3.

[0053] Optionally, refer to Figure 5 , Figure 8 As shown, the inclination angle α of the inclined plane is 2° to 5°. For example, the inclination angle α can be 2°, 3°, 4°, 5°, etc.

[0054] In this embodiment, the tilt angle α of the upper surface of the cover ring 2 is 2° to 5°, which can ensure the amount of gas flowing through the upper surface of the wafer 3 without affecting the deposition effect on the upper surface of the wafer 3, and can also suppress the gas from passing through the edge of the wafer 3, thereby improving the "white spot" phenomenon on the back side of the wafer 3.

[0055] In some embodiments of this application, reference is made to Figure 3 , Figure 4 As shown, a first positioning part 2233 is provided on the inner side 223 of the protrusion 22, and the side of the first positioning part 2233 facing the groove area 111 is a plane.

[0056] By setting the first positioning part 2233, the directionality is stronger when placing the wafer 3, making it easier to place the wafer 3 in place in one step.

[0057] Optionally, refer to Figure 3 , Figure 4 As shown, the first positioning part 2233 is located inside the first part 221, 223.

[0058] Optionally, refer to Figure 3 , Figure 4 As shown, the carrier plate 1 is provided with a second positioning part 1121. After the cover ring 2 is closed on the carrier plate 1, the second positioning part 1121 is positioned opposite to the first positioning part 2233. This allows the cover ring 2 to be quickly closed on the carrier plate 1, and the closing position is repeatable each time. Of course, the wafer 3 is also provided with a positioning edge 31 so that the wafer 3 can be quickly placed in the recess area 111, and the placement position is repeatable each time.

[0059] A second aspect of this application provides an epitaxial device comprising the aforementioned carrier disk assembly.

[0060] In this embodiment of the epitaxial apparatus, the cover ring 2 in the carrier disk assembly includes a protrusion 22. The protrusion 22 forms a cover plate structure above the wafer 3, reducing the gap S between the lower surface of the protrusion 22 and the upper surface of the wafer 3. This makes it difficult for gas to enter the gap between the wafer 3 and the sidewall of the recess region 111, thereby reducing the probability of gas entering the back side of the wafer 3. Therefore, epitaxial growth using this carrier disk assembly can avoid the formation of "white spots" on the back side of the wafer 3.

[0061] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0062] The various embodiments in this specification are described in a related manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0063] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A carrier disk assembly, characterized in that, include: A carrier disk (1), the first surface (11) of the carrier disk (1) includes a groove region (111) and an edge region (112) surrounding the groove region (111), the groove region (111) is formed by the first surface (11) of the carrier disk (1) being recessed to a first depth toward the second surface (12) of the carrier disk (1), the groove region (111) includes a wafer placement area (1111); A cover ring (2) is fitted onto the carrier disk (1). The cover ring (2) includes a body part (21) and a protrusion (22). The body part (21) fits onto the edge area (112). The protrusion (22) is connected to the body part (21) and protrudes toward the side near the groove area (111), and is suspended above the groove area (111). The protrusion (22) has an overlapping portion (1111a) with the wafer placement area (1111) in the orthographic projection of the carrier disk (1).

2. The carrier disk assembly according to claim 1, characterized in that, The protrusion (22) includes a first part (221) and a second part (222), the second part (222) being the portion that is sunk into the groove area (111).

3. The carrier disk assembly according to claim 2, characterized in that, The thickness of the second part (222) is 0.1 mm to 0.3 mm.

4. The carrier disk assembly according to claim 2, characterized in that, There is a gap (S) between the lower surface of the second part (222) and the upper surface of the wafer (3) of the wafer placement area (1111), and the gap (S) is 0.1 mm to 0.2 mm.

5. The carrier disk assembly according to claim 1, characterized in that, The inner side (223) of the protrusion (22) includes an annular surface (2231) and a conical surface (2232). The conical surface (2232) is located on the side of the annular surface (2231) close to the wafer (3), and the diameter of the conical surface (2232) gradually increases along the direction close to the wafer (3) to avoid the upper surface of the wafer (3).

6. The carrier disk assembly according to claim 5, characterized in that, The diameter of the bottom edge of the conical surface (2232) is equal to the diameter of the wafer (3).

7. The carrier disk assembly according to claim 1, characterized in that, The width of the protrusion (22) at the overlap (1111a) between the orthographic projection of the bearing disk (1) and the bearing area of ​​the wafer (3) is 0.3 mm to 1.0 mm.

8. The carrier disk assembly according to claim 1, characterized in that, The upper surface (23) of the cover ring is inclined, and along the direction close to the groove area (111), the upper surface (23) of the cover ring gradually moves away from the first surface (11) of the support plate (1).

9. The carrier disk assembly according to claim 8, characterized in that, The inclination angle (α) of the inclined plane is 2° to 5°.

10. An epitaxial device, characterized in that, The extensional device includes the carrier disk assembly according to any one of claims 1-9.

Images