Epitaxial base for eight-inch silicon wafer

Abstract

An epitaxial base for an eight-inch silicon wafer comprises a graphite base body with a wafer groove for placing the silicon wafer, a slot penetrating through the wafer groove is formed in the side wall of the graphite base body, the boundary line of the slot and the wafer groove corresponds to the boundary line of a reference face part and an arc-shaped part of the silicon wafer, and an insertion block is inserted in the slot. The side wall, facing the wafer groove, of the insertion block is a plane and corresponds to the reference face portion of the silicon wafer, the length of the insertion groove and the length of the insertion block are both larger than the length of the reference face portion of the silicon wafer, and the two sides, facing the side wall of the wafer groove, of the insertion block abut against the boundary line of the insertion groove and the wafer groove respectively. On the basis of conveniently cleaning the folded angles of the sheet grooves in the graphite base body, the cleaning amount of personnel is reduced, the machining precision requirement of accessories is reduced, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon wafer epitaxial production, and specifically relates to an epitaxial pedestal for an eight-inch silicon wafer. Background Art

[0002] During the silicon wafer epitaxial production, a silicon carbide layer is synchronously deposited and adhered to the side wall of the graphite pedestal body for placing the silicon wafer, resulting in a decrease in the inner diameter of the wafer groove of the graphite pedestal body, and it is necessary for personnel to regularly align and clean it. It is relatively easy to clean the silicon carbide on the arc portion and the reference face of the silicon wafer shown in Figure 7 However, it is relatively difficult to clean the fold angle position at the junction of the arc portion and the reference face in the wafer groove. This is not only due to the physical cleaning obstacles caused by the geometric structure of this position, where narrow grooves or ridges are formed in the fold angle area, and it is difficult for cleaning tools (such as ultrasonic probes, brushes, or airflows) to fully reach, easily forming cleaning blind spots. The arc of the arc portion needs to be closely fitted to the side wall of the substrate (to prevent reaction gas leakage during epitaxial growth), and residues (such as silicon carbide particles, graphite dust, or by-products) are easily compacted in the fold angle gap. Moreover, there are micropores on the surface of the graphite pedestal, and reaction by-products (such as deposits of SiC, Si, or C) may penetrate into the pores and adhere, especially at the fold angle where they are more likely to accumulate due to stress concentration. During epitaxial growth, high temperatures (usually >1500 °C) will cause local sintering or chemical bonding between the residues and the graphite surface, forming a dense hard layer that is difficult to peel off during mechanical cleaning. In addition, due to the structural mutation, the fold angle area becomes a stress concentration point, and the mechanical forces (such as scraping, ultrasonic vibration) applied during cleaning may cause microcracks or peeling of the graphite.

[0003] To solve the cleaning of this position, CN210506587U discloses a graphite pedestal for silicon carbide epitaxial growth, which solves the problem of easy damage when cleaning the deposited silicon carbide at the fold angle by setting a detachable insert on the side wall of the pedestal. However, this solution has the following defects:

[0004] 1. Extremely high processing accuracy requirements: The insert and the pedestal slot need to fit perfectly, otherwise silicon carbide will still be deposited in the tiny gaps, increasing the cleaning amount for personnel.

[0005] 2. The fitting degree decreases after long-term use: In a high-temperature environment, the graphite pedestal and the insert may generate micro-gaps due to differences in thermal expansion coefficients, further exacerbating the deposition problem.

[0006] 3. High maintenance cost: Ultra-precision machining increases the manufacturing cost, and frequent disassembly and assembly may accelerate the wear of the insert and the slot, affecting the service life. Summary of the Invention

[0007] The present invention aims to provide an epitaxial base for an eight-inch silicon wafer, which can reduce the amount of manual cleaning, lower the precision requirements for accessory processing, and extend the service life while facilitating the cleaning of the corner of the wafer groove in the graphite base body.

[0008] To solve the above technical problems, the specific solution adopted by the present invention is as follows: An epitaxial base for an eight-inch silicon wafer includes a graphite base body having a wafer groove for placing silicon wafers. A slot penetrating the wafer groove is provided on the side wall of the graphite base body. The intersection line of the slot and the wafer groove corresponds to the intersection line of the reference surface and the arc portion of the silicon wafer. An insert block is inserted into the slot. The side wall of the insert block facing the wafer groove is a plane and corresponds to the reference surface of the silicon wafer. The lengths of the slot and the insert block are both greater than the length of the reference surface of the silicon wafer. The two sides of the side wall of the insert block facing the wafer groove respectively abut against the intersection line of the slot and the wafer groove.

[0009] Preferably, the length of the slot is greater than the length of the insert block, and the width of the slot is greater than the width of the insert block.

[0010] Preferably, a high-temperature resistant elastic material is provided on the side of the insert block in the slot that is opposite to the wafer groove, and the high-temperature resistant elastic material is used to press the insert block towards the wafer groove.

[0011] Preferably, the slot is filled with a high-temperature resistant elastic material around the insert block. The high-temperature resistant elastic material on the side of the insert block that is opposite to the wafer groove is used to press the insert block towards the wafer groove, and the remaining high-temperature resistant elastic material is used to fill the gap between the slot and the insert block.

[0012] Preferably, the high-temperature resistant elastic material is a silicon carbide fiber gasket or a honeycomb ceramic gasket.

[0013] Preferably, the side of the insert block opposite to the wafer groove is a first inclined surface, and the side wall of the slot corresponding to the first inclined surface is a second inclined surface. The inclination angles of the first inclined surface and the second inclined surface are the same.

[0014] Preferably, after the insert block slides along the second inclined surface through the first inclined surface until it abuts against the intersection line of the slot and the wafer groove, the gap between the bottom of the insert block and the bottom of the slot is less than the thickness of the silicon wafer.

[0015] Preferably, the inner diameter of the wafer groove decreases from top to bottom. After the silicon wafer falls on the inner wall of the wafer groove, the gap between the bottom of the insert block and the bottom of the slot is located below the silicon wafer.

[0016] By optimizing the cooperation mode between the insert block and the slot, the present invention has the following advantages compared with the prior art:

[0017] 1. Reducing the dependence on processing precision: The insert block directly abuts against the intersection line of the slot and the wafer groove. Even if there are minor processing errors, physical contact can block the deposition of silicon carbide without the need for perfect fitting. The inclined surface and the elastic material further compensate for the tolerance to ensure that the insert block always adheres tightly to the intersection line.

[0018] 2. Completely avoid deposition gaps: The length of the insert block is greater than the reference surface of the silicon wafer, so that its two sides always cover the junction line, eliminating the possibility of silicon carbide infiltrating into the slot. The gap around the insert block is filled with a high-temperature resistant elastic material to provide dynamic sealing.

[0019] 3. Extend the maintenance cycle: The contact surface between the insert block and the base does not require precise matching, reducing the replacement frequency caused by wear. The elastic material buffers the thermal stress and reduces the deformation risk of the insert block and the slot.

[0020] 4. Cost optimization: Omit the ultra-precision machining process to reduce the manufacturing cost. The modular insert block design allows for individual replacement, further saving maintenance costs.

[0021] In summary, while retaining the advantage of easy cleaning of the split base, this application solves the contradiction between machining accuracy and long-term sealing through structural innovation, and is especially suitable for the efficient production of large-size silicon wafer epitaxy. Brief Description of the Drawings

[0022] Figure 1 Fig. 1 is a top view structural schematic diagram of Embodiment 1 of an epitaxial base for an eight-inch silicon wafer according to the present invention;

[0023] Figure 2 is Figure 1 a structural schematic diagram after removing the insert block and the high-temperature resistant elastic material in Fig. 1;

[0024] Figure 3 Fig. 2 is a top view structural schematic diagram of Embodiment 2 of an epitaxial base for an eight-inch silicon wafer according to the present invention;

[0025] Figure 4 Fig. 3 is a top view structural schematic diagram of Embodiment 3 of an epitaxial base for an eight-inch silicon wafer according to the present invention;

[0026] Figure 5 is Figure 4 a sectional structural schematic diagram taken along the A-A direction in Fig. 2;

[0027] Figure 6 Fig. 4 is a partial sectional structural schematic diagram of Embodiment 4 of an epitaxial base for an eight-inch silicon wafer according to the present invention;

[0028] Figure 7 Fig. 5 is a structural schematic diagram of a silicon wafer;

[0029] Reference numerals in the drawings: 1, graphite base body; 2, wafer groove; 3, high-temperature resistant elastic material; 4, insert block; 5, slot; 6, silicon wafer; 7, first inclined surface; 8, second inclined surface; 9, reference surface; 10, arc portion. Detailed Description of the Invention

[0030] The following describes an epitaxial base for an eight-inch silicon wafer 6 of the present invention through four embodiments:

[0031] Embodiment 1

[0032] As Figure 1 and Figure 2 shown, the epitaxial base for an eight-inch silicon wafer 6 in this embodiment includes a graphite base body 1. Similar to the patent related to the background technology, a wafer groove 2 is provided at its top, and a slot 5 penetrating the wafer groove 2 is opened on the side wall. An insert block 4 is inserted into the slot 5, and the side wall facing the wafer groove 2 is a plane for fitting the reference surface of the silicon wafer 6.

[0033] However, different from the patent related to the background technology, the length of the insert block 4 in this embodiment is slightly greater than the length of the reference surface of the silicon wafer 6, covering the entire junction line area to avoid silicon carbide deposition. On the back side of the slot 5, that is, the side of the slot 5 away from the wafer groove 2, a high-temperature resistant elastic material 3 is filled, such as a silicon carbide fiber gasket. This material remains elastic at high temperatures and continuously presses the insert block 4 towards the wafer groove 2, ensuring that the two side edges of the insert block 4 always closely adhere to the junction line between the slot 5 and the wafer groove 2. Through the above structure, the tight contact between the insert block 4 and the junction line can avoid the settlement of silicon carbide in the gap between the two without ultra-high machining accuracy, thereby greatly reducing the manufacturing cost.

[0034] In addition, there are relatively large gaps between the back side of the insert block 4 and the slot 5, as well as between the left and right sides of the insert block 4 and the insert block 4 itself. Silicon carbide can be deposited freely without the need for cleaning, which does not affect the implementation and use of this embodiment.

[0035] Embodiment 2

[0036] As Figure 3 shown, this embodiment further optimizes the sealing performance on the basis of Embodiment 1: The high-temperature resistant elastic material 3 not only fills the back side of the insert block 4, but also wraps all the gaps on its outer periphery. The thickness of the insert block 4 is slightly smaller than the width of the slot 5 to provide a compression space for the elastic material.

[0037] In this embodiment, at high temperatures, the elastic material expands and evenly fills the gap between the insert block 4 and the slot 5 to achieve dynamic sealing. At the same time, the insert block 4 is extruded by the elastic material, and its two side edges always press tightly against the junction line, ensuring that the deposition of silicon carbide on the side parts of the insert block 4 and the slot 5 can still be avoided in this application without high-precision machining.

[0038] Embodiment 3

[0039] As Figures 4 - 5 shown, this embodiment cancels the elastic material and realizes the positioning of the insert block 4 through a mechanical structure:

[0040] The back side of the insert block 4 is provided with a first inclined surface 7, and the corresponding position of the slot 5 is provided with a second inclined surface 8, and the inclination angles of the two are the same. During installation, the insert block 4 slides along the second inclined surface 8 until its two sides abut against the intersection line to form self-locking. Thus, in this embodiment, elastic materials are not required, and maintenance is simplified because the high-temperature-resistant materials can be avoided from being replaced due to long-term service and high-temperature aging.

[0041] In addition, in order to ensure that the insert block 4 can abut against the intersection line position of the slot 5 and the chip slot 2 through the sliding fit of the first inclined surface 7 and the second inclined surface, a thinning amount is set at the bottom of the insert block 4 in this embodiment, so that after the insert block 4 abuts against the intersection line position of the slot 5 and the chip slot 2, a gap is generated between the insert block 4 and the bottom of the slot 5. In order to avoid the settlement of silicon carbide in this gap, the thinning amount is set to Figure 5 In the state shown, the gap is smaller than the thickness of the silicon wafer 6, so that the silicon wafer 6 itself seals the gap, avoiding the situation that personnel still need to clean after deposition in the gap, or the insert block 4 cannot slide downward to abut against the intersection line of the slot 5 and the chip slot 2 after deposition.

[0042] Embodiment 4

[0043] As Figure 6 shown, the inner diameter of the chip slot 2 in this embodiment decreases from top to bottom. After the outer edge of the silicon wafer 6 falls on the inner wall of the chip slot 2, the gap between the bottom of the insert block 4 and the bottom of the slot 5 is located below the silicon wafer 6. This embodiment further reduces the design requirements for the thinning amount at the bottom of the insert block 4, ensuring that the silicon wafer 6 can seal the gap to avoid the deposition of silicon carbide in the gap.

Claims

1. An epitaxial base for an eight-inch silicon wafer, comprising a graphite base body (1) having a wafer groove (2) for placing a silicon wafer (6), a slot (5) penetrating the wafer groove (2) being provided on a side wall of the graphite base body (1), the intersection line between the slot (5) and the wafer groove (2) corresponding to the intersection line between a reference surface (9) and an arc-shaped portion (10) of the silicon wafer (6), an insert block (4) being inserted in the slot (5), the side wall of the insert block (4) facing the wafer groove (2) being a plane and corresponding to the reference surface (9) of the silicon wafer (6), characterized in that: The length of the slot (5) and the length of the insert block (4) are both greater than the length of the reference surface (9) of the silicon wafer (6), and the two sides of the side wall of the insert block (4) facing the wafer slot (2) respectively touch the boundary line between the slot (5) and the wafer slot (2).

2. The epitaxial substrate for an eight-inch silicon wafer according to claim 1, characterized in that: The length of the slot (5) is greater than the length of the insert block (4), and the width of the slot (5) is greater than the width of the insert block (4).

3. The epitaxial substrate for an eight-inch silicon wafer according to claim 2, characterized in that: A high temperature resistant elastic material (3) is provided in the slot (5) on the side of the insert block (4) facing away from the sheet slot (2). The high temperature resistant elastic material (3) is used to press the insert block (4) toward the sheet slot (2).

4. The epitaxial substrate for an eight-inch silicon wafer according to claim 2, characterized in that: The outer periphery of the insert block (4) in the slot (5) is filled with a high temperature resistant elastic material (3); the high temperature resistant elastic material (3) located on the side of the insert block (4) facing away from the sheet slot (2) is used to press the insert block (4) toward the sheet slot (2); and the remaining high temperature resistant elastic material (3) is used to fill the gap between the slot (5) and the insert block (4).

5. The epitaxial susceptor for an eight-inch silicon wafer as claimed in claim 3, characterized in that: The high temperature resistant elastic material (3) is a silicon carbide fiber gasket or a honeycomb ceramic gasket.

6. The epitaxial susceptor for an eight-inch silicon wafer according to claim 1, characterized in that: The side of the insert block (4) opposite to the sheet slot (2) is a first inclined surface (7), and the side wall of the slot (5) corresponding to the first inclined surface (7) is a second inclined surface (8), and the first inclined surface (7) and the second inclined surface (8) have the same inclination angle.

7. The epitaxial susceptor for an eight-inch silicon wafer according to claim 6, characterized in that: After the insert (4) slides along the second inclined surface (8) through the first inclined surface (7) until it contacts the boundary line between the slot (5) and the wafer slot (2), the gap between the bottom of the insert (4) and the bottom of the slot (5) is smaller than the thickness of the silicon wafer (6).

8. The epitaxial susceptor for an eight-inch silicon wafer according to claim 6, characterized in that: The inner diameter of the wafer slot (2) decreases from top to bottom. After the silicon wafer (6) falls on the inner wall of the wafer slot (2), the gap between the bottom of the insert block (4) and the bottom of the slot (5) is located below the silicon wafer (6).

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