Wafer and processing method thereof

Abstract

The invention provides a wafer and a processing method of the wafer. The wafer comprises a wafer body and an edge structure arranged at the edge of the wafer body, the wafer body comprises a first surface and a second surface which are oppositely distributed along a first direction, and the edge structure comprises a first chamfer part connected with the first surface; a second chamfered portion connected to the second surface; the platform part and the transition chamfering part are formed between the first chamfering part and the second chamfering part and are sequentially arranged from top to bottom in the first direction; the first chamfer part and the transition chamfer part are both R-shaped chamfers, the second chamfer part is a T-shaped chamfer, and the curvature radius of the transition chamfer part is smaller than or equal to that of the first chamfer part. According to the invention, the mechanical strength of the wafer edge is improved, the edge breakage of the wafer is effectively avoided, a gradient chamfering effect is formed between the platform part and the second chamfering part, the covering uniformity of photoresist on the surface of the edge structure is improved, and the precision of a subsequent semiconductor process is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer processing, and in particular to a wafer and a processing method thereof. BACKGROUND

[0002] In the processing of a wafer, the chamfer formed by the edge structure of the wafer is a key link to ensure the quality of the wafer. The traditional chamfer of the edge structure usually adopts a single T-shaped chamfer or R-shaped chamfer, and has the following defects. First, the single chamfer structure leads to insufficient mechanical strength of the edge of the wafer, and the edge is prone to collapse during handling and subsequent processes. Second, the coverage of photoresist in the edge region of the wafer is uneven, which affects the accuracy of subsequent semiconductor processes. In addition, in the chemical mechanical polishing (CMP) process, the wafer is prone to edge over-polishing effect, which affects the quality of the wafer. The foregoing defects seriously restrict the efficiency and quality of wafer manufacturing. Accordingly, it is necessary to improve the edge structure of the wafer and the processing method for forming the edge structure of the wafer in the prior art to solve the above problems and improve the overall quality and efficiency of wafer manufacturing.

[0003] It should be noted that the above introduction to the background art is only for the convenience of clearly and completely describing the technical solutions of the present application, and for the convenience of understanding by those skilled in the art. The above technical solutions cannot be considered as known to those skilled in the art merely because they are described in the background art section of the present application. SUMMARY

[0004] The present application aims to disclose a wafer and a processing method thereof to solve the foregoing technical problems, improve the mechanical strength of the edge of the wafer, avoid the collapse of the edge of the wafer, and improve the quality of the wafer.

[0005] In a first aspect, the present application provides a wafer, comprising a wafer body and an edge structure arranged at the edge of the wafer body, the wafer body comprising a first surface and a second surface oppositely distributed along a first direction, and the edge structure comprising:

[0006] a first chamfer portion connected with the first surface;

[0007] a second chamfer portion connected with the second surface;

[0008] a platform portion and a transition chamfer portion formed between the first chamfer portion and the second chamfer portion and arranged in sequence from top to bottom along the first direction;

[0009] wherein the first chamfer portion and the transition chamfer portion are both R-shaped chamfers, the second chamfer portion is a T-shaped chamfer, and the curvature radius of the transition chamfer portion is less than or equal to the curvature radius of the first chamfer portion.

[0010] As a further improvement of the present invention, the radius of curvature of the first chamfer is 0.1 to 0.3 mm, the angle formed by the second chamfer and the plane containing the second surface is 20° to 50°, and the radius of curvature of the transition chamfer is 0.05 to 0.15 mm.

[0011] As a further improvement of the present invention, the first chamfered portion terminates at the first chamfer boundary along the first direction, and the circumferential tangent at the junction of the first chamfered portion and the platform portion forms an upper chamfer with the first chamfer boundary;

[0012] When the upper chamfer is less than or equal to 90°, the radius of curvature of the first chamfer portion is less than or equal to 1 / 2 of the thickness of the wafer body formed along the first direction.

[0013] When the upper chamfer is greater than 90°, the radius of curvature of the first chamfer portion is less than or equal to the thickness of the wafer body formed along the first direction.

[0014] The curvature change rate of the transition chamfer is 3-5% / μm, and the height of the platform portion along the first direction is 0.03-0.1mm.

[0015] As a further improvement of the present invention, the first chamfered portion has a first length along the second direction, the second chamfered portion has a second length along the second direction, and the second length is greater than the first length; the second direction is perpendicular to the first direction.

[0016] As a further improvement of the present invention, the radius of curvature of the first chamfer is 0.15 to 0.25 mm, and the angle formed between the second chamfer and the plane containing the second surface is 30° to 45°.

[0017] As a further improvement of the present invention, the second chamfered portion is a conical surface, the surface roughness of the conical surface is 5 to 10 nm, and the tolerance of the angle formed by the second chamfered portion and the plane containing the second surface is less than or equal to ±0.1°.

[0018] As a further improvement of the present invention, the platform portion is kept parallel to the first direction.

[0019] Secondly, based on the same inventive concept, the present invention also provides a wafer processing method for forming a wafer as described in any of the inventions, the processing method comprising the following steps:

[0020] The edges of the wafer body to be processed are rough-machined to form a first chamfer, a second chamfer, and a transition chamfer.

[0021] The first chamfer connected to the first surface is polished using magnetorheological polishing, the second chamfer connected to the second surface is polished using argon ion beam polishing, and the transition chamfer is polished using femtosecond laser polishing and nanopolishing.

[0022] As a further improvement of the present invention, the magnetorheological polishing process includes: polishing the first chamfered part wetted by the magnetorheological polishing liquid using a polishing disc under the control of an external magnetic field; wherein the magnetorheological polishing liquid includes 30-40%wt carbonyl iron powder, 5-10%wt silica abrasive particles, and 50-65%wt base liquid.

[0023] The carbonyl iron powder has an average particle size of 3 μm, the silica abrasive particles have an average particle size of 40–60 nm, the magnetic field strength formed by the external magnetic field is 1.12–1.35 Tesla, the polishing removal amount is 2–5 μm, and the rotation speed of the polishing disc is 60–100 rpm.

[0024] As a further improvement of the present invention, the femtosecond laser process includes: polishing the transition chamfered portion using a femtosecond laser with a wavelength of 1020-1040 nm; wherein the pulse width of the femtosecond laser is 100-200 fs, the repetition frequency is 1 kHz, and the scanning speed is 0.1-0.2 mm / s.

[0025] The argon ion beam polishing process includes: introducing argon gas and an auxiliary gas into a vacuum environment, ionizing the argon gas to form argon plasma that bombards the surface of the transition chamfer; wherein the flow rate ratio of the argon gas to the auxiliary gas is 1:1 to 2:1, and the power density of the ionized argon gas is 0.5 to 1 W / cm³. 2 The scanning speed is 0.5 to 1 mm / s.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] In this invention, the wafer edge structure is configured such that a first chamfer, a second chamfer, a plateau, and a transition chamfer are sequentially formed from the first surface, creating a composite chamfer structure at the wafer edge. By configuring the first chamfer and the transition chamfer as R-shaped chamfers, the mechanical strength of the wafer edge is significantly improved, effectively preventing edge chipping during handling and processing, thus ensuring wafer stability and quality. Simultaneously, configuring the transition chamfer as an R-shaped chamfer creates a gradient chamfer effect between the plateau and the second chamfer, thereby improving the uniformity of photoresist coverage on the edge structure surface, preventing stress concentration between the plateau and the second chamfer, improving the overall wafer quality, and ensuring the precision of subsequent semiconductor processes. Attached Figure Description

[0028] Figure 1 It is a partial cross-sectional view of the edge structure of the wafer of the present invention included in one embodiment;

[0029] Figure 2 It is a partial cross-sectional view of the edge structure of the wafer of the present invention included in another embodiment;

[0030] Figure 3 It is a partial cross-sectional view of the edge structure in which the first chamfered portion forms an upper chamfer of less than or equal to 90°;

[0031] Figure 4 It is a partial cross-sectional view of the edge structure in which the first chamfered portion forms an upper chamfer of greater than 90°;

[0032] Figure 5 It is an overall flowchart of a processing method for a wafer of the present invention. Specific Embodiments

[0033] The present invention will be described in detail below in conjunction with the embodiments shown in the accompanying drawings. It should be noted, however, that these embodiments are not limitations of the present invention, and any equivalent transformation or substitution in terms of function, method, or structure made by those of ordinary skill in the art based on these embodiments shall fall within the protection scope of the present invention.

[0034] The accompanying drawings in the present invention are not strictly drawn to actual scale, and the specific dimensions of each structure can be determined according to actual needs. The accompanying drawings described in the present invention are only schematic diagrams. The lines shown in the accompanying drawings of the specification of the present invention can be understood as components having a certain actual thickness or shape, or representing spatial positions.

[0035] Refer Figure 1 to Figure 2 As shown, it shows two specific embodiments of the wafer 1000 obtained based on the processing method of the wafer referred to in the present invention. The edge structure formed at the edge of the wafer to be processed along the second direction 2 can be in a vertical state or in a form with a slightly rounded corner. Through the processing method of the wafer disclosed in the present invention, the wafer 1000 as shown in Figure 1 is formed. For simplicity of representation, only the wafer 1000 with the edge structure 3 or the edge structure 3a formed by processing is shown, and it is a partial cross-sectional view located on one side of the central axis 100 where the center of the circle is located.

[0036] As Figure 1 shown, the wafer 1000 includes a wafer body 10 and an edge structure 3 provided at the edge of the wafer body 10. The wafer body 10 includes a first surface 11 and a second surface 16 that are relatively distributed along the first direction 1. The first surface 11 is formed above the wafer 1000, the second surface 16 is formed below the wafer 1000, and the first surface 11 and the second surface 16 are parallel to each other.

[0037] The edge structure 3 includes a first chamfered portion 12, a second chamfered portion 15, a platform portion 13, and a transition chamfered portion 14. The first chamfered portion 12 is connected to the first surface 11, and the second chamfered portion 15 is connected to the second surface 16. The platform portion 13 and the transition chamfered portion 14 are formed between the first chamfered portion 12 and the second chamfered portion 15 and are arranged sequentially from top to bottom along the first direction 1. Both the first chamfered portion 12 and the transition chamfered portion 14 are R-shaped chamfers, and the second chamfered portion 15 is a T-shaped chamfer. The radius of curvature R2 of the transition chamfered portion 14 is less than or equal to the radius of curvature R1 of the first chamfered portion 12. Figure 1 The radius of curvature R1 of the first chamfer 12 can be appropriately reduced, as can be referred to Figure 2 As shown.

[0038] The platform portion 13 remains parallel to the first direction 1, thereby forming a ring-shaped curved surface. The first chamfer portion 12 terminates at the first chamfer boundary 132 along the first direction 1, and the surface of the bottom 121 of the first chamfer portion 12 along the first direction 1 smoothly transitions to the surface of the platform portion 13. The second direction 2 is perpendicular to the first direction 1. Figure 1 The radius of curvature R2 of the transition chamfer 14 in the view is small in scale, so it is not shown or labeled in detail, but can be found in the reference section. Figure 2 The radius of curvature R2 of the transition chamfer 14a is shown. The bottom of the platform portion 13 along the first direction 1 ends at the upper boundary 131 of the second chamfer, and the bottom of the transition chamfer 14 along the first direction 1 ends at the lower boundary 141 of the second chamfer. The height difference of the transition chamfer 14 along the first direction 1 is defined between the upper boundary 131 and the lower boundary 141 of the second chamfer. The height of the platform portion 13 along the first direction 1 is h, and the height h is jointly defined by the first chamfer boundary 132 and the upper boundary 131 of the second chamfer.

[0039] The bottom of the transition chamfer portion 14 and the surface of the second chamfer portion 15 are naturally and smoothly transitioned. At the same time, the transition chamfer portion 14 is configured as an R-shaped chamfer, so that the transition chamfer portion 14 forms a gradient chamfer effect and a natural and smooth transition between the platform portion 13 and the second chamfer portion 15, thereby improving the uniformity of the photoresist coverage on the surface of the edge structure 3, which is beneficial to the uniform coverage of the photoresist on the edge structure 3, and avoiding stress concentration between the platform portion 13 and the second chamfer portion 15, and especially avoiding the sharp shape formed by the direct adjacent arrangement of the platform portion 13 and the second chamfer portion 15, avoiding stress concentration at the junction of the platform portion 13 and the second chamfer portion 15, further avoiding edge chipping of the wafer 1000, improving the overall quality of the wafer 1000, improving the accuracy of subsequent processes, and being applicable to the processing and shaping of the edge structure 3 (or 3a) of large-sized wafers. Thus, during subsequent processing (such as semiconductor processes like thin film deposition, lithography, ion implantation, etc.) or the transfer stage of the robot handling the wafer, due to slight external forces (such as mechanical contact, thermal stress caused by temperature changes during the transfer of the wafer between different semiconductor equipment stations / areas), cracks or chipping phenomena caused at the edge structure 3 (or 3a) are avoided, effectively preventing the wafer 1000 from cracking.

[0040] Optionally, the radius of curvature R1 of the first chamfer portion 12 is 0.1 - 0.3 mm. Preferably, the radius of curvature R1 of the first chamfer portion 12 is 0.15 - 0.25 mm; the angle a formed by the second chamfer portion 15 and the plane of the second surface 16 is 20° - 50°, and can be any integer or non-integer angle. Preferably, the angle a is 30° - 45°; the radius of curvature R2 of the transition chamfer portion 14 is 0.05 - 0.15 mm.

[0041] Since the radius of curvature R1 of the first chamfer portion 12 has a fixed relationship with the thickness t of the wafer. The larger the thickness t of the wafer, the larger the allowable radius of curvature R1 of the first chamfer portion 12, ensuring the unified shape of the edge structure 3 (or 3a) of wafers with different thickness specifications (such as wafers with standard thickness or thinned wafers, etc.), being able to stably adapt to the mechanical design of semiconductor equipment (such as clamping force, positioning accuracy), and reducing mechanical damage (such as scratching, chipping) caused by mechanical operations exerted by semiconductor equipment on the wafer 1000.

[0042] See Figure 3 and Figure 4 shown, Figure 3 The radius of curvature R1 of the first chamfer portion 12 of the edge structure 3 in Figure 4 is greater than the radius of curvature R1 of the first chamfer portion 12 of the edge structure 3 in

[0043] As Figure 3As shown, the first chamfered portion 12 terminates at the first chamfer boundary 132 along the first direction 1. The circumferential tangent 122 at the intersection of the first chamfer boundary 132 and the platform portion 13 (i.e., the bottom 121 of the first chamfered portion 12 along the first direction 1) forms an upper chamfer b with the first chamfer boundary 132, and the upper chamfer b is less than or equal to 90°. The circumferential tangent 122 lies in a vertical plane (not shown) perpendicular to the direction of the center of the wafer 1000, and the vertical plane is perpendicular to the plane where the wafer 1000 is located, and coincides with the central axis 100 where the center of the wafer 1000 is located. At this time, the radius of curvature R1 of the first chamfered portion 12 is less than or equal to 1 / 2 of the thickness t formed by the wafer body 10 along the first direction 1, and greater than or equal to 1 / 4 of the thickness t formed by the wafer body 10 along the first direction 1. In this example, the upper chamfer b is an acute angle, and the entire first chamfer 12 is located radially inside the annular contour formed by the platform 13 and is in a recessed state; thereby, the edge structure 3 can be prevented from protruding radially outward, thereby reducing the direct collision stress with other objects (such as wafer boxes, robotic arms) and avoiding edge chipping.

[0044] like Figure 4 As shown, the first chamfered portion 12 terminates at the first chamfer boundary 132 along the first direction 1. The circumferential tangent 123 at the intersection of the first chamfer boundary 132 and the platform portion 13 (i.e., the bottom 121 of the first chamfered portion 12 along the first direction 1) forms an upper chamfer c with the first chamfer boundary 132, and the upper chamfer c is greater than 90°. The circumferential tangent 123 lies in a vertical plane (not shown) perpendicular to the direction of the center of the wafer 1000, and the vertical plane is perpendicular to the plane where the wafer 1000 is located, and coincides with the central axis 100 where the center of the wafer 1000 is located. At this time, the radius of curvature R1 of the first chamfered portion 12 is less than or equal to the thickness t formed by the wafer body 10 along the first direction 1. In this example, the upper chamfer c is an obtuse angle, and a part of the first chamfered portion 12 is located radially outside the annular contour formed by the platform portion 13, and exhibits a slightly outward expansion.

[0045] In various embodiments of the present invention, the thickness t of the wafer 1000 and the radius of curvature R1 of the first chamfer 12 and the upper chamfer b (or c) form the aforementioned proportional relationship, making the shape of the first chamfer 12 more regular and the transition between the edge of the first chamfer 12 and the surface of the platform 13 smoother. Simultaneously, it also ensures that the shape of the edge structure 3 (or 3a) of wafers 1000 of different specifications is uniform, so as to stably adapt to the mechanical design of semiconductor equipment (such as clamping force, positioning accuracy), and reduce mechanical damage such as scratches or breakage during mechanical operation or handling. It is understood that... Figure 3 and Figure 4 The correspondence between the radius of curvature R1 of the first chamfer 12 shown and the thickness t of the wafer 1000 and the upper chamfer b (or c) also applies to... Figure 2Edge structure 3a in wafer 1000.

[0046] For example, in instances where the angle of the upper chamfer b is less than or equal to 90°, and the radius of curvature R1 of the first chamfer portion 12 is less than or equal to 1 / 2 of the thickness t formed by the wafer body 10 along the first direction 1, and greater than or equal to 1 / 4 of the thickness t formed by the wafer body 10 along the first direction 1, it can be ensured that the edge of the first chamfer portion 12 at its bottom is completely located radially inside the annular contour formed by the platform portion 13. This not only helps to reduce interference with the roughing and finishing of the surfaces of the first chamfer portion 12 and the platform portion 13 during transverse processing, but also helps to prevent stress accumulation in the edge structure 3 (or 3a), and is particularly beneficial to prevent stress accumulation at the bottom 121 where the first chamfer portion 12 and the platform portion 13 meet. At the same time, it also helps to meet the process requirements and application scenarios where the side surface of the edge structure 3 (or 3a) requires a certain degree of flatness, thereby helping to reduce the boundary size of the first chamfer portion 12 and avoid the first chamfer portion 12 from being excessively convex.

[0047] For example, in instances where the angle of the upper chamfer c is greater than 90°, by setting the radius of curvature R1 of the first chamfer portion 12 to be less than or equal to the thickness t of the wafer 1000, a certain degree of roundness can be maintained while preventing excessive outward expansion of the bottom edge of the first chamfer portion 12, which would affect the processing range for roughing and finishing the surfaces of the first chamfer portion 12 and the platform portion 13. This also helps improve the impact resistance of the edge structure 3 (or 3a), and is particularly beneficial for improving the impact resistance of the first chamfer portion 12. Ultimately, this reduces edge defects in the wafer 1000, increases the effective utilization area of ​​the wafer 1000, and allows chips (dies) near the edge region to maintain a high yield. The aforementioned edge region is located on the first surface 11 near the annular edge region of the edge structure 3 (or 3a).

[0048] The curvature change rate of the transition chamfer 14 is 3-5% / μm, and the height of the platform portion 13 along the first direction 1 is 0.03-0.1mm. The first chamfer 12 has a first length 21 along the second direction 2, and the second chamfer 15 has a second length 20 along the second direction 2, the second length 20 being greater than the first length 21. The lengths of the first length 21 and the second length 20 refer to the lengths formed by the orthographic projection of each chamfer portion from the center of the wafer 1000 onto the plane containing the wafer 1000.

[0049] Furthermore, the included angle α formed by the second chamfered portion 15 and the plane of the second surface 16 is 30° to 45°, and can be any integer or non-integer angle. The second chamfered portion 15 is a conical surface, and the surface roughness of the conical surface is 5 to 10 nm. The tolerance of the included angle formed by the second chamfered portion 15 and the plane of the second surface 16 is less than or equal to ±0.1°. The curvature radius R1 of the first chamfered portion 12 is 0.15 to 0.25 mm. The curvature radius R1 of the first chamfered portion 12 should not be too large to avoid the edge of the wafer 1000 exceeding the clamping range of the positioning groove or chuck of the semiconductor device (not shown), thereby preventing the wafer 1000 from shifting, slipping during transmission, or generating process defects such as scratches due to friction with the components of the semiconductor device.

[0050] Refer Figure 2 Another example of the wafer 1000 of the present invention shown in the figure. The wafer 1000 includes a wafer body 10 and an edge structure 3a provided at the edge of the wafer body 10. The wafer body 10 includes a first surface 11 and a second surface 16 that are oppositely distributed along the first direction 1.

[0051] The edge structure 3a includes: a first chamfered portion 12, a second chamfered portion 15, a platform portion 13a, and a transition chamfered portion 14a. The first chamfered portion 12 is connected to the first surface 11; the second chamfered portion 15 is connected to the second surface 16; the platform portion 13a and the transition chamfered portion 14a are formed between the first chamfered portion 12 and the second chamfered portion 15 and are arranged in sequence from top to bottom along the first direction 1. Both the first chamfered portion 12 and the transition chamfered portion 14a are R-shaped chamfers, the second chamfered portion 15 is a T-shaped chamfer, and the curvature radius R2 of the transition chamfered portion 14a is less than or equal to the curvature radius R1 of the first chamfered portion 12. The platform portion 13a included in the edge structure 3a of the wafer 1000 forms a certain included angle with the first direction 1, and the included angle can be any integer or non-integer angle between 1° and 15°, so that the platform portion 13a and the transition chamfered portion 14a form an integral structure and are in an outward-expanded shape, which further helps to avoid stress concentration in the edge structure 3a and is beneficial to improving the surface quality and overall quality of the wafer 1000. The aforementioned surface covers the first surface 11, the second surface 16, and the surface formed by the edge structure 3 located between the first surface 11 and the surface 16.

[0052] The platform portion 13 forms a conical annular curved surface and expands outward at the bottom along the first direction 1. The first chamfer portion 12 terminates along the first direction 1 at the first chamfer boundary 132. The surface of the first chamfer portion 12 at the bottom 122 along the first direction 1 and the surface of the platform portion 13 have a natural smooth transition. The bottom formed by the platform portion 13a along the first direction 1 terminates at the upper boundary 131a of the second chamfer. The bottom formed by the transition chamfer portion 14 along the first direction 1 terminates at the lower boundary 141 of the second chamfer. The height difference of the transition chamfer portion 14a along the first direction 1 is defined between the upper boundary 131a of the second chamfer and the lower boundary 141 of the second chamfer. The height of the platform portion 13a along the first direction 1 is h'. The first chamfer boundary 132 and the upper boundary 131a of the second chamfer jointly define the height h. The tangent direction of the bottom surface of the transition chamfer portion 14a and the surface of the second chamfer portion 15 have a natural smooth transition. At the same time, the transition chamfer portion 14a is configured as an R-shaped chamfer, so that the transition chamfer portion 14a forms a gradient chamfer effect and a natural smooth transition between the platform portion 13a and the second chamfer portion 15, thereby improving the uniformity of the photoresist coverage on the surface of the edge structure 3a, which is beneficial to the uniform coverage of the photoresist on the edge structure 3a and avoids stress concentration between the platform portion 13a and the second chamfer portion 15. The first chamfer boundary 132, the upper boundary 131 (or 131a) of the second chamfer, the lower boundary 141 of the second chamfer, the first surface 11, and the second surface 16 are all parallel along the second direction 2.

[0053] In addition, the second chamfer portion 15 located below the first chamfer portion 12 is T-shaped and is connected to the second surface 16 at the bottom, which is beneficial for the wafer 1000 to be bonded or encapsulated with a substrate (not shown) during subsequent bonding processes and / or packaging processes to form a semiconductor device. The substrate includes but is not limited to a glass substrate, a wafer substrate, or a sapphire substrate, etc., and is beneficial to improve the stability of the contact formed with the substrate located below the wafer 1000 and can improve the bonding strength between the wafer 1000 and the substrate. The diameter of the wafer 1000 is at least 12 inches and may include 8 inches, 6 inches, 4 inches, 2 inches, or 1 inch, etc. The wafer 1000 includes: a silicon-based wafer, or a non-silicon-based wafer such as a III-V nitride wafer (e.g., GaN wafer, AlN wafer, etc.), or a non-silicon-based wafer such as a silicon carbide wafer.

[0054] Figure 2 In the second example shown, the wafer 1000 and Figure 1 The same technical solutions as those in the first example corresponding thereto are as described in the first specific embodiment and will not be elaborated herein.

[0055] Refer to Figure 5The illustration shows an example of a wafer processing method according to the present invention. In this example, the wafer to be processed is processed by the wafer processing method to form a wafer 1000 as in any of the foregoing embodiments. The wafer processing method includes the following steps 101 and 102, or steps 101 to 103; wherein, step 101 is a roughing stage, step 102 is a finishing stage, and step 103 is an inspection stage.

[0056] Step 101: Roughly process the edge of the wafer body 10 to be processed to form a first chamfer 12, a second chamfer 15 and a transition chamfer 14 (or 14a).

[0057] The first chamfer 12, the second chamfer 15, and the transition chamfer 14 (or 14a) formed in step 101 are all in their original final morphology and have already formed a basic outline. In the roughing stage, a diamond grinding wheel can be used for preliminary shaping. A five-axis linkage grinding machine is used to ensure geometric machining accuracy. The upper axis drives the grinding wheel's revolution, the lower axis drives the grinding wheel's feed, the left and right axes limit the grinding wheel's oscillation, and the rear axis drives the grinding wheel's lifting and lowering. The machining equipment used for roughing is not a point of invention in this application and is not described in detail in this embodiment.

[0058] The roughing time should be controlled within 60% to 70% of the total processing time. During the roughing stage, excess material can be quickly removed, ensuring that the dimensions of the first chamfer 12 or the second chamfer 15 formed after roughing are close to the target dimensions and basic surface morphology, thereby improving overall processing efficiency. If the roughing time is less than 60% of the total processing time, insufficient material removal will result in a large amount of remaining material needing to be processed during the finishing stage. This will not only prolong the total processing time but also increase the polishing cost in subsequent step 102 and reduce processing accuracy due to excessive load during the finishing stage. If the roughing time exceeds 70% of the total processing time, insufficient machining allowance for finishing will result in the inability to correct surface errors from the roughing process (e.g., minor chipping, dimensional deviations, large roughness, etc.) during the finishing stage, thus affecting the final accuracy.

[0059] Optionally, after performing step 101, a margin of several micrometers to tens of micrometers is reserved between the edge surface of the wafer body 10 and each expected surface of the finally formed edge structure 3 (3a).

[0060] Step 102: Polish the first chamfer 12 connected to the first surface 11 using magnetorheological polishing process, polish the second chamfer 15 connected to the second surface 16 using argon ion beam polishing process, and polish the transition chamfer 14 (or 14a) using femtosecond laser process and nano-polishing process.

[0061] The magnetorheological polishing process includes polishing the first chamfered portion 12, which is immersed in a magnetorheological polishing slurry, using a polishing disc under the control of an external magnetic field. The magnetorheological polishing slurry comprises 30–40 wt% carbonyl iron powder, 5–10 wt% silica abrasive particles, and 50–65 wt% base liquid. The carbonyl iron powder is key to the rheological effect of the magnetorheological slurry, and its particle size and content affect the performance of the slurry. The nano-sized silica abrasive, as the main cutting component, has a particle size and content that determines the cutting ability and surface quality of the magnetorheological polishing slurry on the material (i.e., the wafer body 10).

[0062] Optionally, the average particle size of the carbonyl iron powder is 3 μm, the average particle size of the silica abrasive particles is 40–60 nm, the magnetic field strength of the external magnetic field is 1.12–1.35 Tesla (T), the polishing removal amount is 2–5 μm, and the polishing disc rotation speed is 60–100 rpm. The magnetic field strength determines the degree of solidification and polishing pressure of the magnetorheological polishing slurry. The higher the strength, the better the solidification effect of the magnetorheological polishing slurry, the greater the polishing pressure, and the faster the removal rate of surface material on edge structure 3 (or 3a). However, excessively high magnetic field strength may lead to a decrease in the surface quality of the wafer. Therefore, it is necessary to reasonably control the magnetorheological polishing time and the quality of magnetorheological polishing. Specifically, the magnetic field strength is controlled within the range of 1.12–1.35 T to comprehensively control the polishing time of the magnetorheological polishing process based on the magnetic field strength.

[0063] The femtosecond laser process includes polishing the transition chamfer 14 (or 14a) with a femtosecond laser with a wavelength of 1020–1040 nm; wherein the pulse width of the femtosecond laser is 100–200 fs, the repetition frequency is 1 kHz, and the scanning speed is 0.1–0.2 mm / s.

[0064] The argon ion beam polishing process includes: placing the wafer to be processed in a vacuum environment, and introducing argon gas and an auxiliary gas into the vacuum environment; ionizing the argon gas to form argon plasma to bombard the surface of the transition chamfer 14 (or 14a). The flow rate ratio of argon gas to auxiliary gas is 1:1 to 2:1, and the power density of the ionized argon gas is 0.5 to 1 W / cm³. 2 The scanning speed is 0.5–1 mm / s. Oxygen can be used as the auxiliary gas.

[0065] The execution order of magnetorheological polishing and argon ion beam polishing can be sequential. Femtosecond laser polishing and nanopolishing can be performed last, after the magnetorheological polishing and argon ion beam polishing processes are completed, to facilitate a natural and smooth transition between the upper and lower ends of the transition chamfer 14 (or 14a) and the surfaces between the platform 13 (or 13a) and the second chamfer 15, respectively. This invention, through a combination of magnetorheological finishing and ion beam figuring (IBF), effectively reduces over-polishing of the edge structure 3 (or 3a) during chemical mechanical polishing, significantly improving the surface quality and edge morphology of wafer 1000, and meeting high-precision processing requirements.

[0066] Step 103: Real-time detection of surface morphology data of edge structure 3 (or 3a) to adjust the process parameters of magnetorheological polishing, argon ion beam polishing, femtosecond laser polishing and nanopolishing based on the surface morphology data.

[0067] The aforementioned surface morphology inspection to obtain surface morphology data can be performed on wafer 1000 in real time using an online white light interferometer to monitor various process parameters (e.g., magnetic field strength, polishing pressure, argon to auxiliary gas flow ratio, etc.) during the polishing process of edge structure 3 (or 3a) in the finishing stage, thereby obtaining inspection data. Then, machine learning algorithms are used to analyze the inspection data in real time and automatically adjust the process parameters. The process parameters are considered to be any one or more of the following: magnetorheological polishing, argon ion beam polishing, femtosecond laser polishing, and nano-polishing. Since the machine learning algorithm is not an improvement on the prior art, it is omitted from this specification.

[0068] The following section presents two specific examples of wafer fabrication methods.

[0069] Example 1

[0070] This embodiment provides a silicon-based wafer (hereinafter referred to as "wafer 1000") with a diameter of 300 mm, comprising: a first chamfer portion 12 connected to a first surface 11, a plateau portion 13, a transition chamfer portion 14, and a second chamfer portion 15 connected to a second surface 16. The first chamfer portion 12 adopts an R-shaped chamfer with a radius of curvature R1 of 0.2 mm; the second chamfer portion 15 adopts a T-shaped chamfer with a 45° bevel; the height h of the plateau portion 13 is 0.05 mm; the radius of curvature R2 of the transition chamfer portion 14 is 0.05 mm, and the curvature change rate is 3% / μm. Wafer 1000 is formed by the following wafer processing method.

[0071] 1) Rough machining stage: A five-axis linkage grinding machine (not shown) is used for preliminary shaping. The upper axis drives the grinding wheel to revolve, the lower axis drives the grinding wheel to feed, the left and right axes restrict the oscillation of the grinding wheel, and the rear axis drives the grinding wheel to rise and fall. The five-axis linkage grinding machine is existing technology and will not be described in detail here.

[0072] 2) Finishing Stage: The first chamfer 12 is polished using magnetorheological polishing. The magnetorheological polishing slurry consists of 40% wt carbonyl iron powder, 5% wt silica abrasive particles, and 50-65% wt base liquid. The silica abrasive has an average particle size of 50 nm, a solid content of 45%, and the remainder is base liquid. The polishing removal amount is 3 μm. The second chamfer 15 is polished using argon ion beam polishing. The argon to oxygen gas flow ratio is 1.5:1, and the power density is 0.8 W / cm³. 2 The scanning speed is 0.8 mm / s; the transition chamfer 14 is polished using femtosecond laser technology and nano-polishing technology. The wavelength of the femtosecond laser is 1030 nm, the pulse width of the femtosecond laser is 150 fs, the repetition frequency is 1 kHz, and the scanning speed is 0.15 mm / s.

[0073] 3) Detection and feedback phase, see above for details.

[0074] Example 2

[0075] The wafer 1000 in this embodiment includes: a first chamfered portion 12 connected to the first surface 11, a plateau portion 13, a transition chamfered portion 14, and a second chamfered portion 15 connected to the second surface 16. The first chamfered portion 12 adopts an R-shaped chamfer, and the radius of curvature R1 of the first chamfered portion 12 is 0.25 mm; the second chamfered portion 15 adopts a T-shaped chamfer, and the second chamfered portion 15 forms a 30° bevel; the height h of the plateau portion 13 is 0.08 mm; the radius of curvature R2 of the transition chamfered portion 14 is 0.15 mm, and the curvature change rate is 5% / μm. The wafer 1000 is formed by the wafer processing method described below.

[0076] 1) Rough machining stage: A five-axis linkage grinding machine (not shown) is used for preliminary shaping. The upper axis drives the grinding wheel to revolve, the lower axis drives the grinding wheel to feed, the left and right axes restrict the oscillation of the grinding wheel, and the rear axis drives the grinding wheel to rise and fall. The five-axis linkage grinding machine is existing technology and will not be described in detail here.

[0077] 2) Finishing Stage: The first chamfer 12 is polished using magnetorheological polishing. The magnetorheological polishing slurry consists of 40% wt carbonyl iron powder, 8% wt silica abrasive particles, and 50-65% wt base liquid. The average particle size of the nano-silica abrasive is 40 nm, the solid content is 48%, and the remainder is base liquid. The polishing removal amount is 4 μm. The second chamfer 15 is polished using argon ion beam polishing. The argon to oxygen gas flow ratio is 2:1, and the power density is 1 W / cm³. 2 The scanning speed is 0.6 mm / s; the transition chamfer 14 is polished using femtosecond laser industrial nanopolishing process. The wavelength of the femtosecond laser is 1030 nm, the pulse width of the femtosecond laser is 180 fs, the repetition frequency is 1 kHz, and the scanning speed is 0.2 mm / s.

[0078] This invention employs a processing method that combines multi-axis linkage control and femtosecond laser-assisted nanopolishing, which significantly improves the positioning accuracy of the robotic arm in automated handling systems, solves the problem of limited positioning accuracy of robotic arms in traditional methods, and achieves precise control of 1000 wafers.

[0079] 3) Detection and feedback phase, see above for details.

[0080] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

[0081] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A wafer comprising a wafer body and an edge structure provided at an edge of the wafer body, the wafer body comprising a first surface and a second surface oppositely distributed along a first direction, characterized in that, The edge structure comprises: a first chamfer connected with the first surface; a second chamfer connected with the second surface; a platform and a transition chamfer formed between the first chamfer and the second chamfer and arranged in sequence from top to bottom along the first direction; wherein the first chamfer and the transition chamfer are R-type chamfers, the second chamfer is a T-type chamfer, and the curvature radius of the transition chamfer is less than or equal to the curvature radius of the first chamfer.

2. The wafer of claim 1, wherein, The curvature radius of the first chamfer is 0.1-0.3 mm, the included angle formed between the second chamfer and the plane where the second surface is located is 20-50°, and the curvature radius of the transition chamfer is 0.05-0.15 mm.

3. The wafer of claim 1, wherein, The first chamfer is cut off at a first chamfer boundary along the first direction, and a circumferential tangent line at the joint of the first chamfer and the platform forms an upper chamfer with the first chamfer boundary; when the upper chamfer is less than or equal to 90°, the curvature radius of the first chamfer is less than or equal to 1 / 2 of the thickness of the wafer body along the first direction; when the upper chamfer is greater than 90°, the curvature radius of the first chamfer is less than or equal to the thickness of the wafer body along the first direction; the curvature variation rate of the transition chamfer is 3-5% per μm, and the height of the platform along the first direction is 0.03-0.1 mm.

4. The wafer of claim 1, wherein, The first chamfer has a first width along the second direction, the second chamfer has a second width along the second direction, and the second width is greater than the first width; the second direction is perpendicular to the first direction.

5. The wafer of claim 2, wherein, The curvature radius of the first chamfer is 0.15-0.25 mm, and the included angle formed between the second chamfer and the plane where the second surface is located is 30-45°.

6. The wafer of claim 2, wherein, The second chamfer is a conical surface, the surface roughness of the conical surface is 5-10 nm, and the tolerance of the included angle formed between the second chamfer and the plane where the second surface is located is less than or equal to ±0.1°.

7. The wafer of any of claims 1-6, wherein, The platform is parallel to the first direction.

8. A method of processing a wafer to form a wafer as claimed in any one of claims 1 to 7, characterised in that, The processing method comprises the following steps: rough processing the edge of the wafer body to be processed to form the first chamfer, the second chamfer, and the transition chamfer; polishing the first chamfer connected with the first surface using a magnetorheological polishing process, polishing the second chamfer connected with the second surface using an argon ion beam polishing process, and polishing the transition chamfer using a femtosecond laser process and a nano-polishing process.

9. The method of claim 8, wherein, The magnetorheological polishing process comprises polishing the first chamfer immersed in a magnetorheological polishing liquid using a polishing disc under the control of an external magnetic field; wherein the magnetorheological polishing liquid comprises 30-40% wt of carbonyl iron powder, 5-10% wt of silicon dioxide abrasive particles, and 50-65% wt of base liquid. The average particle size of the carbonyl iron powder is 3 microns, the average particle size of the silica abrasive particles is 40-60 nm, the magnetic field strength formed by the external magnetic field is 1.12-1.35 Tesla, the polishing removal amount is 2-5 microns, and the rotation speed of the polishing disc is 60-100 rpm.

10. The method of claim 8, wherein, The femtosecond laser process comprises: polishing the transition chamfer portion by using a femtosecond laser with a wavelength of 1020-1040 nm; wherein the pulse width of the femtosecond laser is 100-200 fs, the repetition frequency is 1 kHz, and the scanning speed is 0.1-0.2 mm / s. The argon ion beam polishing process comprises: introducing argon and auxiliary gas into a vacuum environment, ionizing the argon to form argon plasma to bombard the surface of the transition chamfer; wherein the flow ratio of the argon to the auxiliary gas is 1:1-2:1, the power density of the ionized argon is 0.5-1 W / cm 2 , and the scanning speed is 0.5-1 mm / s.

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