Wafer limiting ring and epitaxial growth equipment

Abstract

A wafer positioning ring and epitaxial growth equipment are disclosed. The wafer positioning ring has an inner ring and an outer ring radially. The wafer positioning ring includes a first part and a second part, which are connected end-to-end circumferentially. The inner ring contour of the first part is an arc, and the inner ring contour of the second part is an arc shape, with the arc shape protruding towards the center of the arc. By setting the inner ring of the wafer positioning ring to an arc-shaped first part and an arc-shaped second part, during wafer placement and rotation, the wafer edge can only contact the arc-shaped contour of the inner ring of the wafer positioning ring. This effectively avoids rigid jamming and collision between the wafer's flat edge and the wafer positioning ring, significantly reducing the risk of wafer chipping and cracking, improving wafer epitaxial growth yield and equipment operational stability, while also reducing equipment downtime and chamber cleaning time due to wafer damage, thus improving overall production efficiency.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a wafer limiting ring and epitaxial growth equipment. Background Technology

[0002] Silicon carbide (SiC), as a third-generation semiconductor material, possesses excellent properties such as a wide bandgap, high thermal conductivity, high breakdown field strength, and resistance to high temperatures and high voltages, making it widely used in power devices, radio frequency devices, and optoelectronic devices. In the fabrication process of silicon carbide devices, epitaxial growth is a key process step in forming the functional layer of high-performance devices. The industry commonly uses high-temperature chemical vapor deposition (HTCVD) for homogeneous epitaxial growth, typically performed in a high-temperature chamber environment of 1550℃ to 1650℃. During epitaxial growth, the silicon carbide wafer is placed on a support structure consisting of a stage and a wafer carrier ring. The wafer, stage, and wafer carrier ring rotate synchronously, ensuring that the reactive gas source can uniformly contact the wafer surface, guaranteeing the uniformity of the epitaxial layer thickness and concentration. Wafer carrier rings are typically made of high-temperature resistant graphite and have a ring structure with an inner and outer ring along the radial direction. The inner ring's contour matches the outer circumference of the wafer, serving to radially position and circumferentially constrain the wafer. This ensures the wafer's positional stability under high-temperature and rotational conditions, making it a crucial support component for maintaining epitaxial growth stability and thin film quality. The entire support and constraint structure, along with the gas path, temperature control, and transmission system of the epitaxial equipment, works together to achieve continuous and stable deposition of silicon carbide single-crystal thin films, providing compliant epitaxial substrates for subsequent device fabrication.

[0003] However, current wafer carrier rings still have shortcomings. Summary of the Invention

[0004] The technical problem solved by this invention is how to improve the structure of the wafer carrier ring to avoid jamming the wafer's flat edge angle and reduce the risk of wafer edge chipping and cracking.

[0005] To solve the above-mentioned technical problems, embodiments of the present invention provide a wafer positioning ring, wherein the wafer positioning ring has an inner ring and an outer ring along the radial direction, and the wafer positioning ring includes: a first part and a second part, the first part and the second part being connected end to end along the circumferential direction, the inner ring contour of the first part being an arc, and the inner ring contour of the second part being an arc shape, the arc shape protruding towards the center of the arc.

[0006] Optionally, the central angle corresponding to the second part is smaller than the central angle corresponding to the first part.

[0007] Optionally, the width of the second portion of the wafer positioning ring is not less than the width of the first portion of the wafer positioning ring, wherein the width is the radial dimension of the wafer positioning ring.

[0008] Optionally, the width of the second portion of the wafer limiting ring first increases and then decreases along the circumferential direction.

[0009] Optionally, the minimum cross-sectional radius of the inner ring is in the range of 71.2 mm to 72.2 mm.

[0010] Optionally, the outer contour of the first portion extends and connects to the outer contour of the second portion.

[0011] Optionally, the wafer limiting ring is suitable for 6-inch wafers.

[0012] Accordingly, embodiments of the present invention also provide an epitaxial growth apparatus, comprising: a reaction chamber; an epitaxial tray located within the reaction chamber, the epitaxial tray being adapted to rotate axially under the drive of a driving mechanism; and a wafer positioning ring as described in embodiments of the present invention, one side of the wafer positioning ring facing the epitaxial tray and the other side of the wafer positioning ring facing the wafer to support the wafer.

[0013] Optionally, the epitaxial growth equipment is a silicon carbide epitaxial growth equipment.

[0014] Optionally, the reaction temperature of the epitaxial growth equipment is greater than 1500°C.

[0015] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects: In the wafer positioning ring of the present invention, the inner ring of the wafer positioning ring is configured as a first part in the shape of an arc and a second part in the shape of an arc. During the wafer placement and rotation process, the wafer edge can only contact the arc-shaped contour of the inner ring of the wafer positioning ring, effectively avoiding rigid jamming and collision between the wafer flat edge and the wafer positioning ring, significantly reducing the risk of wafer chipping and cracking, improving the yield of wafer epitaxial growth and the stability of equipment operation, while reducing equipment downtime and chamber cleaning time caused by wafer damage, and improving overall production efficiency.

[0016] In an optional embodiment of this invention, the wafer positioning ring is suitable for 6-inch wafers. A 6-inch wafer has a flat edge ground to serve as a positioning edge, providing a reference for wafer crystal alignment and mechanical positioning, ensuring that the photolithographic pattern is consistent with the cleavage direction of the crystal, and achieving precise positioning of the wafer during exposure, coating, and development steps. The designed wafer positioning ring ensures that the wafer edge only contacts the arc-shaped contour of the inner ring, effectively preventing rigid jamming between the flat edge angle of the 6-inch wafer and the wafer positioning ring, significantly reducing the risk of edge chipping and cracking. Attached Figure Description

[0017] Figure 1 This is a top view of a wafer locating ring; Figure 2 This is a top view schematic diagram of a wafer limiting ring according to some embodiments of the present invention; Figure 3 This is a partial top view schematic diagram of a wafer limiting ring according to some embodiments of the present invention; Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure of the wafer limiting ring at position A1A2. Detailed Implementation

[0018] As can be seen from the background technology, the wafer limiting ring in the existing technology still has shortcomings. The reasons for these problems are analyzed below: Please refer to Figure 1 A wafer positioning ring 100 has an inner ring 100a and an outer ring 100b in the radial direction. The wafer positioning ring 100 includes a curved edge portion II and a straight edge portion I. The curved edge portion II and the straight edge portion I are connected end to end in the circumferential direction. The inner ring 100a of the curved edge portion II has an arc outline, and the inner ring 100a of the straight edge portion I has a line segment outline.

[0019] Specifically, Figure 1 Except for the straight edge part I, all the parts are curved edge parts II.

[0020] The wafer positioning ring 100 is suitable for 6-inch wafers. The outline of the 6-inch wafer is formed by an arc and a flat edge, and the arc and the flat edge form an angle between them.

[0021] During the silicon carbide (SiC) epitaxial growth process, the wafer is placed on the wafer locating ring 100, which in turn is placed on the epitaxial tray. The wafer, the wafer locating ring 100, and the epitaxial tray rotate under the drive of the epitaxial equipment's drive mechanism.

[0022] In the initial stage of rotation, the wafer will be relatively displaced relative to the wafer limiting ring 100. The flat edge of the 6-inch wafer will come into contact with the straight edge I of the wafer limiting ring 100. When the rotation speed is high, the flat edge of the wafer is easily stuck in the straight edge I of the wafer limiting ring 100. Under the action of high temperature, the wafer will expand and contract, and the wafer is prone to edge chipping. In severe cases, the wafer is easy to break into fragments.

[0023] The above situation will cause the wafer to be scrapped directly. If wafer fragments remain in the reaction chamber of the equipment, the equipment will not be able to operate normally. It is necessary to open the equipment to find the fragments remaining in the reaction chamber. Therefore, it is necessary to perform operations such as cooling, purging, opening the chamber, removing the residual fragments, cleaning the chamber, closing the chamber, vacuuming, filling with gas, helium detection, heating, temperature calibration, and readjusting the specifications. Completing the above actions takes 10 to 12 hours, which greatly reduces production efficiency.

[0024] To solve the aforementioned technical problem, the present invention provides a wafer positioning ring, wherein the wafer positioning ring has an inner ring and an outer ring along the radial direction, and the wafer positioning ring includes: a first part and a second part, the first part and the second part being connected end to end along the circumferential direction, the inner ring contour of the first part being an arc, and the inner ring contour of the second part being an arc shape, the arc shape protruding towards the center of the arc.

[0025] In the wafer positioning ring of this invention, the inner ring of the wafer positioning ring is configured as a first part in the shape of an arc and a second part in the shape of an arc. During wafer placement and rotation, the wafer edge can only contact the arc-shaped contour of the inner ring of the wafer positioning ring, effectively avoiding rigid jamming and collision between the wafer's flat edge and the wafer positioning ring. This significantly reduces the risk of wafer chipping and cracking, improves the yield of wafer epitaxial growth and the stability of equipment operation, and reduces equipment downtime and chamber cleaning time caused by wafer damage, thereby improving overall production efficiency.

[0026] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0027] Please refer to Figure 2 The wafer positioning ring 200 has an inner ring 200a and an outer ring 200b in the radial direction, wherein the side of the wafer positioning ring 200 closer to the center in the radial direction is the inner ring 200a, and the side of the wafer positioning ring 200 further away from the center in the radial direction is the outer ring 200b.

[0028] Please refer to Figure 2 The wafer positioning ring 200 includes: a first part I, wherein the inner ring 200a of the first part I has an arc outline.

[0029] Specifically, in the embodiments of the present invention, the wafer limiting ring 200 is adapted to carry and limit the wafer in the silicon carbide (SiC) epitaxial growth process, and to constrain the circumferential position of the wafer during the synchronous rotation of the wafer and the wafer limiting ring.

[0030] The inner ring 200a of the first part I has an arc outline, such as... Figure 2As shown, the cross-sectional radius r1 of the inner ring 200a of the first part I is a constant. The cross-section is a plane perpendicular to the axis of the wafer locating ring 200. The cross-sectional radius r1 refers to the length of a line segment from the center of the wafer locating ring 200 to any point on the inner ring 200a of the first part I within the plane perpendicular to the axis of the wafer locating ring 200.

[0031] For details, please continue to refer to [the website / information]. Figure 2 The outer ring 200b of the first part I has an arc outline, and the cross-sectional radius R1 of the outer ring 200b of the first part I is a constant value. The cross-sectional radius R1 refers to the length of a line segment from the center of the wafer limiting ring 200 to any point on the outer ring 200b of the first part I in a plane perpendicular to the axis of the wafer limiting ring 200.

[0032] The outer ring 200b of the wafer positioning ring 200 is adapted to contact and cooperate with the epitaxial tray. Through the contact and support between the outer ring 200b and the epitaxial tray, the wafer positioning ring 200 is installed and positioned on the epitaxial tray, thereby reliably supporting and circumferentially limiting the wafer.

[0033] Please continue to refer to this. Figure 2 The wafer limiting ring 200 includes: a second part II, which is connected to the first part I in the circumferential direction. The inner circle 200a of the second part II has an arc shape, and the arc shape protrudes towards the center of the arc.

[0034] The circumferential direction refers to the circumferential direction around the center of the wafer limiting ring 200.

[0035] The inner circle 200a of the second part II has an arc shape, that is, the inner circle 200a of the second part II has a continuous smooth curve.

[0036] Specifically, in some embodiments of the present invention, the inner contour of the second part can be an arc; in other embodiments of the present invention, the inner contour of the second part can be a parabola.

[0037] Specifically, in this embodiment of the invention, the first part I and the second part II are sequentially connected circumferentially to form a closed and complete ring without interruption. That is, one end of the first part I is connected to one end of the second part II, and the other end of the first part I is connected to the other end of the second part II, together forming a complete and closed wafer limiting ring 200. The inner ring 200a contour of the second part II is adjacent to the inner ring 200a contour of the first part I, that is, the inner ring 200a contour of the first part I and the inner ring 200a contour of the second part II are smoothly connected without any segment connection.

[0038] Specifically, in some embodiments of the present invention, the wafer limiting ring 200 is applicable to 6-inch wafers.

[0039] For 6-inch wafers (150mm in diameter), a flat edge is typically ground out as a positioning edge to provide a reference for wafer crystal orientation alignment, mechanical positioning, etc., ensuring that the photolithography pattern is consistent with the cleavage direction of the crystal, and achieving precise positioning of the wafer in exposure, coating, development and other steps.

[0040] The outline of a 6-inch wafer is formed by an arc and a flat edge, with an angle between the arc and the flat edge.

[0041] In this invention, by setting the inner ring 200a of the wafer limiting ring 200 as an arc-shaped first part I and an arc-shaped second part II, the wafer edge can only contact the arc-shaped contour of the inner ring 200a of the wafer limiting ring 200 during wafer placement and rotation. This effectively avoids rigid jamming and collision between the wafer's flat edge and the wafer limiting ring 200, significantly reducing the risk of wafer edge chipping and cracking, improving wafer epitaxial growth yield and equipment operation stability, while reducing equipment downtime and chamber cleaning time caused by wafer damage, and improving overall production efficiency.

[0042] like Figure 2 As shown, the arc of the second part II of the inner ring 200a protrudes towards the center of the arc of the first part I of the inner ring 200a. The arc protruding towards the center of the arc means that the arc of the inner ring 200a of the second part II bends and bulges towards the center of the arc of the first part I, causing the entire outline of the inner ring 200a of the second part II to converge towards the center of the ring.

[0043] The structure design, which protrudes in the arc towards the center of the arc, can increase the contact area between the second part II and the outer periphery of the wafer, so that the two form a stable surface contact fit, effectively disperse contact stress, and improve the stability of the wafer under high temperature rotation conditions.

[0044] like Figure 2 As shown, the central angle θ2 corresponding to the second part II is less than the central angle θ1 corresponding to the first part I, that is, θ2 < θ1.

[0045] The design allows the first part I, which adapts to the outer periphery of the wafer, to occupy a large circumferential range, ensuring sufficient contact and support area between the wafer and the limiting ring, thus improving wafer positioning stability. At the same time, the second part II, which adapts to the flat edge of the wafer, occupies only a small circumferential range to achieve flat edge positioning, which helps to ensure the positional accuracy and operational stability of the wafer during epitaxial growth.

[0046] Specifically, the outer ring 200b of the second part II has an arc outline, and the outer ring 200b of the first part I extends and connects with the outer ring 200b of the second part II. The cross-sectional radius R2 of the outer ring 200b of the second part II is equal to the cross-sectional radius of the outer ring 200b of the first part I, i.e., R2=R1. The outer ring 200b of the wafer positioning ring 200 is suitable for contact and mating with the epitaxial tray. Through the contact and support between the outer ring 200b and the epitaxial tray, the wafer positioning ring 200 is installed and positioned on the epitaxial tray, thereby reliably supporting and circumferentially limiting the wafer.

[0047] Please continue to refer to this. Figure 2 The width of the second part II of the wafer positioning ring 200 is not less than the width of the first part I of the wafer positioning ring 200, wherein the width is the radial dimension of the wafer positioning ring 200.

[0048] For example, such as Figure 2 As shown, the width of the second part II of the wafer limiting ring 200 is W2, and the width of the first part I of the wafer limiting ring 200 is W1, where W2 ≥ W1.

[0049] Specifically, in some embodiments of the present invention, the range of the ring width W2 of the second part II is: 2.8mm < W2 < 3.8mm.

[0050] Specifically, in some embodiments of the present invention, such as Figure 2 As shown, the ring width of the second part II of the wafer limiting ring 200 first increases and then decreases along the circumference of the wafer limiting ring 200.

[0051] Specifically, in some embodiments of the present invention, the minimum cross-sectional radius r2 of the inner ring 200a is in the range of 71.2mm < r2 < 72.2mm.

[0052] The cross section is a plane perpendicular to the axis of the wafer positioning ring 200. The cross section radius r2 refers to the length of a line segment from the center of the wafer positioning ring 200 to any point on the inner ring 200a of the second part II within the plane perpendicular to the axis of the wafer positioning ring 200.

[0053] By controlling the minimum cross-sectional radius r2 of the inner ring 200a within the range of 71.2mm < r2 < 72.2mm, a reasonable radial fit clearance can be formed between the inner ring 200a contour of the wafer limiting ring 200 and the wafer. This ensures that the wafer can be smoothly placed into the limiting ring, avoiding assembly jamming, and effectively restricts the radial movement of the wafer during high-temperature rotation. This balances assembly convenience and positioning stability, and improves the reliability of the epitaxial growth process.

[0054] Please refer to the reference. Figure 3 and Figure 4 , Figure 4 for Figure 3 In the cross-sectional structural diagram at position A1A2, the wafer limiting ring 200 includes: a receiving surface 2001, the receiving surface 2001 having a step, the step being disposed along the edge of the inner ring 200a, and the step extending circumferentially to close and form an annular step structure, the position of the step being suitable to correspond to the edge position of the wafer to fix the wafer.

[0055] Specifically, the wafer limiting ring 200 has two opposing sides, and the receiving surface 2001 is the side facing the wafer during the silicon carbide epitaxial growth process.

[0056] The step is positioned to correspond to the edge of the wafer, that is, the step is positioned to contact the edge of the wafer.

[0057] Specifically, such as Figure 4 As shown, the receiving surface 2001 includes a first sub-step surface 20011, a second sub-step surface 20012, and a third sub-step surface 20013 distributed radially in sequence. The first sub-step surface 20011, the second sub-step surface 20012, and the third sub-step surface 20013 all extend and close circumferentially. The second sub-step surface 20012 connects the first sub-step surface 20011 and the third sub-step surface 20013. The surface of the first sub-step surface 20011 is recessed in the second sub-step surface 20012, and the step is formed between the first sub-step surface 20011 and the second sub-step surface 20012.

[0058] Specifically, the first sub-step surface 20011, the second sub-step surface 20012, and the third sub-step surface 20013 are integrally formed.

[0059] Specifically, the surface of the first sub-step 20011 is recessed into the second sub-step 20012 to form the step, and the step and the first sub-step 20011 are adapted to contact the edge of the wafer.

[0060] Specifically, in some embodiments of the present invention, the material of the wafer limiting ring 200 includes graphite.

[0061] Accordingly, embodiments of the present invention also provide an epitaxial growth apparatus, comprising: a reaction chamber; an epitaxial tray located within the reaction chamber, the epitaxial tray being adapted to rotate axially under the drive of a driving mechanism; and a wafer positioning ring 200 as described in embodiments of the present invention, one side of the wafer positioning ring 200 facing the epitaxial tray, and the other side of the wafer positioning ring 200 facing the wafer to support the wafer.

[0062] The epitaxial growth equipment includes a reaction chamber.

[0063] The reaction chamber provides a closed and clean reaction environment for epitaxial growth, which can isolate external impurities and ensure the stable operation of the epitaxial growth process.

[0064] The epitaxial growth apparatus includes an epitaxial tray located within the reaction chamber, the epitaxial tray being adapted to rotate axially under the drive of a driving mechanism.

[0065] The epitaxial tray is used to support and drive the wafer to rotate. Axial rotation can make the wafer heat up evenly and the airflow distribution evenly in the reaction chamber, thereby improving the thickness and performance uniformity of the epitaxial layer.

[0066] The epitaxial growth apparatus includes a wafer positioning ring 200 as described in the embodiments of the present invention, one side of the wafer positioning ring 200 facing the epitaxial tray, and the other side of the wafer positioning ring 200 facing the wafer to support the wafer.

[0067] The wafer positioning ring 200 provides stable support and positioning for the wafer by attaching one side to the epitaxial tray and supporting the wafer on the other side, thus preventing the wafer from shifting or shaking during rotation and facilitating wafer placement and positioning.

[0068] Specifically, the epitaxial growth equipment is a silicon carbide epitaxial growth equipment.

[0069] Silicon carbide epitaxial growth equipment is a specialized device that uses high-temperature chemical vapor deposition (HTCVD) to grow a high-quality, low-defect single-crystal epitaxial layer on the surface of silicon carbide wafers. It is mainly used in the manufacture of power semiconductor devices. The equipment achieves uniform, low-defect thin film growth through high temperature, precise temperature control, stable airflow, and wafer rotation support structure, making it a core piece of equipment in the silicon carbide power device industry chain.

[0070] Specifically, the reaction temperature of the epitaxial growth equipment is greater than 1500℃. The wafer limiting ring 200 using the technical solution of this invention can significantly reduce the risk of wafer edge chipping and cracking under high-temperature reactions, thereby improving the yield of wafer epitaxial growth.

[0071] In summary, the technical solution of this invention, by setting the inner ring of the wafer limiting ring into a first arc-shaped part and a second arc-shaped part, ensures that the wafer edge only contacts the arc-shaped contour of the inner ring of the wafer limiting ring during wafer placement and rotation. This effectively avoids rigid jamming and collision between the wafer's flat edge and the wafer limiting ring, significantly reducing the risk of wafer chipping and cracking, improving wafer epitaxial growth yield and equipment operation stability, while reducing equipment downtime and chamber cleaning time due to wafer damage, and improving overall production efficiency.

[0072] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A wafer positioning ring, wherein the wafer positioning ring has an inner ring and an outer ring along the radial direction, characterized in that, The wafer limiting ring includes: The first part and the second part are connected end to end in the circumferential direction. The inner circle of the first part is an arc and the inner circle of the second part is an arc shape, which protrudes towards the center of the arc.

2. The wafer positioning ring as described in claim 1, characterized in that, The central angle corresponding to the second part is smaller than the central angle corresponding to the first part.

3. The wafer positioning ring as described in claim 1, characterized in that, The width of the second portion of the wafer positioning ring is not less than the width of the first portion of the wafer positioning ring, wherein the width is the radial dimension of the wafer positioning ring.

4. The wafer positioning ring as described in claim 3, characterized in that, The width of the second part of the wafer limiting ring first increases and then decreases along the circumferential direction.

5. The wafer positioning ring as described in claim 1, characterized in that, The minimum cross-sectional radius of the inner ring ranges from 71.2 mm to 72.2 mm.

6. The wafer positioning ring as described in claim 1, characterized in that, The outer contour of the first part extends and connects with the outer contour of the second part.

7. The wafer positioning ring as described in claim 1, characterized in that, The wafer limiting ring is suitable for 6-inch wafers.

8. An epitaxial growth apparatus, characterized in that, include: reaction chamber; An epitaxial tray, located within the reaction chamber, is adapted to rotate axially under the drive of a driving mechanism; The wafer positioning ring as described in any one of claims 1 to 7, wherein one side of the wafer positioning ring faces the epitaxial tray and the other side of the wafer positioning ring faces the wafer to support the wafer.

9. The epitaxial growth apparatus as described in claim 8, characterized in that, The epitaxial growth equipment is a silicon carbide epitaxial growth equipment.

10. The epitaxial growth apparatus as described in claim 8, characterized in that, The reaction temperature of the epitaxial growth equipment is greater than 1500℃.

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