Wafer thinning carrier, manufacturing method and application thereof

Abstract

The application discloses a wafer thinning carrier, a manufacturing method thereof and application. The wafer thinning carrier body comprises a carrier body, the carrier body is provided with a plurality of convex parts, the plurality of convex parts are sequentially and spacedly arranged along the circumference of the carrier body, and the plurality of convex parts enclose a containing groove for placing a wafer, the wafer can be arranged in the containing groove, and the thickness of the wafer is greater than the depth of the containing groove. The convex parts on the carrier body of the wafer thinning carrier body are distributed in a ladder shape, so that the stress in grinding does not have a large mutation, wafer fragments are further avoided, and the problem of uneven grinding is avoided. A wafer thinning method is performed by using the wafer thinning carrier body provided by the application, the end of the process is predicted according to the change of force, and the wafers on the carrier body used in the application are distributed in a ladder shape, so that the stress in grinding does not have a large mutation, the stability of the process can be maintained, and the mutation of the power of the grinding equipment is prevented.

Description

Technical Field

[0001] This invention relates to a wafer thinning carrier, its manufacturing method and application, belonging to the field of semiconductor technology. Background Technology

[0002] As is well known, with the application of large-scale and ultra-large-scale integrated circuits, higher requirements have been placed on the miniaturization, lightweighting, and multifunctionality of devices, leading to an ever-increasing demand for ultra-thin chips. Currently, ultra-thin chips are used in fields such as memory chips and multi-chip packaging.

[0003] For a given material, thinner devices generally have better heat dissipation. However, manufacturing even thinner devices presents a significant challenge to the production process. The grinding process for thinner devices is prone to fragmentation, leading to a decrease in yield. The paper "A Method for Improving the Grinding Yield of Warped Sapphire Wafers" (publication number CN112542373A) mentions using grooving on the first and second surfaces to reduce fragmentation during sapphire thinning. Grooving serves both a heat dissipation function and a release of stress generated during grinding, thus reducing fragmentation. However, this paper only addresses thinning wafers thicker than 120µm; it does not mention thinning thinner wafers. Furthermore, the paper "An Optimized Method for Bonding and Thinning of Semiconductor Wafers" (publication number CN104658927A) mentions thinning after bonding, but this method suffers from drawbacks such as complex processes, high implementation difficulty, and challenges in debonding. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a wafer thinning carrier, its manufacturing method and application.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0006] The present invention provides a wafer thinning carrier body, comprising: a carrier body, a receiving groove and a plurality of protrusions; wherein, the carrier body has a first side and a second side facing away from each other; the receiving groove is formed on the first side of the carrier body and is used to receive a wafer; the plurality of protrusions are spaced apart on the first side of the carrier body and distributed around the receiving groove.

[0007] In one specific embodiment, the size of the protrusion in the first direction gradually decreases along the second direction, the first direction being parallel to the first surface of the vehicle body, and the second direction being perpendicular to the first direction and gradually moving away from the vehicle body.

[0008] In one specific embodiment, the protrusion is trapezoidal.

[0009] In one specific embodiment, the carrier body is made of any one of sapphire, SiC, or Si.

[0010] In one specific embodiment, the receiving groove is circular, and a plurality of the protrusions are evenly distributed on the edge of the receiving groove, with the central angle corresponding to each protrusion being 30 to 45°.

[0011] In one specific embodiment, the central angle between two adjacent protrusions is 10° to 30°.

[0012] In one specific embodiment, the height of the protrusion is greater than the thickness of the wafer.

[0013] In one specific embodiment, the sum of the depth of the receiving groove and the height of the protrusion is less than or equal to the thickness of the wafer, and the depth of the receiving groove is greater than the thickness of the wafer thinned to a set thickness value.

[0014] The present invention also provides a method for fabricating a wafer thinning carrier, comprising:

[0015] A vehicle body is provided, the vehicle body having a first side and a second side facing away from each other;

[0016] A receiving groove is formed on the first surface of the carrier body, the receiving groove being used to receive a wafer;

[0017] A plurality of protrusions are machined on the first surface of the vehicle body at intervals, and the plurality of protrusions are arranged around the receiving groove.

[0018] The present invention also provides a wafer thinning apparatus, including a grinding mechanism and the aforementioned wafer thinning carrier, wherein the grinding mechanism is used to grind the wafer and the wafer is fixed inside the wafer thinning carrier.

[0019] In one specific embodiment, the wafer thinning equipment further includes a force sensing mechanism, which is connected to the grinding mechanism and is used at least to detect changes in the grinding force during the grinding process.

[0020] The present invention also provides a wafer thinning method, comprising: providing the wafer thinning carrier and fixing the wafer to be thinned in the receiving groove of the wafer thinning carrier;

[0021] The wafer is ground until its thickness is reduced to a set thickness value.

[0022] In one specific embodiment, the wafer and the protrusion are ground, and the grinding force is continuously monitored during the grinding process. When the grinding force reaches a preset threshold, it is determined that the thickness of the wafer has reached a set thickness value.

[0023] Compared with the prior art, the advantages of the present invention include:

[0024] 1) The wafer thinning carrier body provided by the present invention is provided with a protrusion, which can prevent the stress from changing a large abruptly during grinding, thereby maintaining the stability of the process, preventing sudden changes in the power of the grinding equipment, and further avoiding wafer fragmentation and grinding unevenness problems.

[0025] 2) The wafer thinning method provided by the present invention has a protrusion arranged along the circumference of the carrier body, which can play the role of monitoring the grinding thickness. During the process of grinding the wafer to the set thickness, especially when grinding the wafer from the pre-processing thickness to the set thickness, the grinding force will change. The process will be known to be about to end based on the change in force. In addition, the wafers on the carrier body are distributed in a trapezoidal shape, which can prevent large abrupt changes in stress during grinding. This can maintain the stability of the process, prevent sudden changes in the power of the grinding equipment, and avoid problems such as wafer fragmentation and uneven grinding. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a wafer thinning carrier provided by the present invention;

[0027] Figure 2 for Figure 1 A top view of a wafer thinning carrier;

[0028] Figure 3 for Figure 1 A schematic diagram of the protrusions on the seed wafer thinning carrier;

[0029] Figure 4 This is a schematic diagram of another wafer thinning carrier provided by the present invention;

[0030] Figure 5 This is a schematic diagram of the bonding between a wafer thinning carrier and a wafer to be thinned, provided by the present invention.

[0031] Figure 6 A process flow diagram of a wafer thinning method provided by the present invention;

[0032] Explanation of reference numerals in the attached drawings: 1. Vehicle body; 11. Reception slot; 12. Protrusion. Detailed Implementation

[0033] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0034] Example 1

[0035] Please see Figure 1 This embodiment provides a wafer thinning carrier body 1, such as... Figure 1 The carrier body 1 shown has a first surface and a second surface arranged opposite to each other. A receiving groove 11 is formed on the first surface of the carrier body 1 and is used to receive a wafer. A plurality of protrusions 12 are spaced apart on the first surface of the carrier body 1 and distributed around the receiving groove 11. A spacer groove is formed between any two adjacent protrusions 12. The wafer thinning carrier body 1 provided by this invention can be used to perform wafer thinning processing. During the thinning process, the wafer thickness is gradually reduced from the first surface of the carrier body 1 to the second surface of the carrier body 1. The protrusions 12 provided on the carrier body 1 can disperse grinding stress, reduce the risk of fragmentation that may occur during the grinding process, and improve the uniformity of the product after grinding.

[0036] And see Figure 3 The protrusion 12 has a dimension that gradually decreases in the first direction along the second direction. The first direction is parallel to the first surface of the vehicle body 1, and the second direction is perpendicular to the first direction and gradually moves away from the vehicle body 1. Specifically, the protrusion 12 can be trapezoidal, and the dimension of the trapezoid in the first direction gradually decreases in the second direction.

[0037] Specifically, the carrier body 1 is made of any one of sapphire, SiC, or Si. Preferably, the carrier body 1 is made of sapphire.

[0038] More specifically, the wafers are mostly circular in shape, and the receiving groove 11 is also circular to fit the shape of the wafer, with multiple protrusions 12 evenly distributed at the edge of the receiving groove 11.

[0039] like Figure 3 As shown, the central angle corresponding to each of the protrusions 12 is 30° to 45°, as... Figure 2 As shown, the central angle between two adjacent protrusions 12 is 10° to 30°. Too small an angle reduces processing efficiency and increases difficulty, while too large an angle weakens the stress-dispersing effect of the protrusions and increases the risk of fragmentation.

[0040] Example 2

[0041] This embodiment provides a wafer thinning carrier, whose structure is basically similar to that of Embodiment 1. The difference lies in that the external shape of the protrusion 12 can be either a regular shape or an irregular shape, and the outer surface of the protrusion 12 can be a plane, a curved surface, or a combination of a plane and a curved surface, making its shape either regular or irregular. The regular shape includes near-circular, trapezoidal, triangular, etc. Of course, its shape can also be other regular polygons or a part of other regular polygons.

[0042] See Figure 3 The protrusion 12 is trapezoidal, and the central angle of the trapezoid is 35°. Compared with the protrusion 12 being triangular, the upper surface of the trapezoid has a certain area. When grinding reaches the upper surface of the trapezoid, the contact area is relatively large, and the contact stress is smaller than that of the triangle, making it less likely for the edge pattern to break during grinding.

[0043] To ensure processing efficiency while maintaining processing quality, the trapezoidal height is generally set to 1.2-2 times the required product thickness. Specifically, when the wafer thickness is reduced to a set thickness value of 50µm, the trapezoidal height is 60-100µm. This is because a higher trapezoidal height reduces processing efficiency, while a thickness below 1.2 times the set thickness increases the difficulty of processing the trapezoidal shape of the carrier and compromises the carrier's stability.

[0044] In a preferred embodiment, the protrusion 12 may be trapezoidal in shape and have two sides. Both sides are angled to the first surface of the vehicle body 1, and the angles between the two sides and the first surface of the vehicle body 1 may be the same. The included angle between the two sides is the central angle corresponding to the protrusion 12, and the central angle may be 30° to 45°.

[0045] Preferably, the two sides of the protrusion 12 can be planes. This can be understood as the protrusion 12 having an approximate isosceles trapezoidal shape. The included angle between the two sides is 30–45°.

[0046] In a preferred embodiment, the plurality of protrusions 12 are evenly spaced along the circumferential direction of the carrier body 1. The uniform arrangement of the trapezoidal shape ensures that the wafer experiences uniform stress during grinding, preventing fragmentation caused by uneven stress distribution during grinding.

[0047] In this embodiment, the protrusions 12 of a wafer thinning carrier body 1 are distributed in a ladder-like shape, which can prevent large abrupt changes in stress during grinding. This can maintain the stability of the process, prevent sudden changes in the power of the grinding equipment, and further avoid wafer fragmentation and grinding inhomogeneity problems.

[0048] Example 3

[0049] This embodiment provides a wafer thinning carrier, whose structure is basically similar to that of Embodiment 1 or Embodiment 2. The difference is that in this embodiment, the height of the protrusion 12 is greater than the thickness of the wafer. It can be understood that at least part of the wafer placed on the carrier body 1 is protruding from the protrusion 12. When the carrier body 1 carries the wafer for thinning, the grinding work can first grind the wafer, and then grind the wafer and the carrier body 1 together. The grinding force will change, and the process can be predicted to be about to end based on the change in force.

[0050] In this embodiment, the receiving groove 11 can be as follows: Figure 1 The settings are as shown, at which point the depth of the receiving groove 11 is the same as the height of the protrusion 12.

[0051] Of course, the accommodating slot 11 can also be as follows: Figure 4 As shown, the first surface of the carrier body 1 is recessed, and the depth of the receiving groove 11 is greater than the height of the protrusion 12. When the grinding process is nearing its end, at least a portion of the wafer can still be embedded in the receiving groove 11, thereby further avoiding the risk of the wafer breaking during the grinding process.

[0052] Example 4

[0053] This embodiment provides a method for fabricating a wafer thinning carrier, which can be applied to the fabrication of the wafer thinning carrier in any of the above embodiments, and includes the following steps:

[0054] A vehicle body l is provided, the vehicle body l having a first side and a second side facing away from each other;

[0055] A receiving groove 11 is formed on the first surface of the carrier body 1, and the receiving groove 11 is used to receive a wafer;

[0056] A plurality of protrusions 12 are machined on the first surface of the carrier body 1 at intervals, and the plurality of protrusions 12 are arranged around the receiving groove 11.

[0057] Specifically, a groove can be cut into the first surface of the body to form a receiving groove 11. Since wafers are mostly circular, the receiving groove 11 is similar in shape to the wafer to be thinned, and therefore the receiving groove 11 can also be circular. An annular protrusion surrounds the receiving groove 11. Further, multiple spacer grooves are formed on the edge of the annular protrusion, and protrusions 12 are formed between the multiple spacer grooves. The protrusions 12 and spacer grooves are alternately arranged. Of course, the above steps of forming the receiving groove 11 and spacer grooves are examples of preferred steps. To form the carrier body 1 provided by this invention, spacer grooves can be formed first at the edge of the body, and then the receiving groove 11 can be formed in the middle of the body. All steps that can form the wafer thinning carrier described in Embodiments 1 and 3 are within the protection scope of this invention.

[0058] Example 5

[0059] This embodiment provides a wafer thinning apparatus, including a grinding device and the wafer thinning carrier from Embodiment 1. The grinding mechanism is used to grind the wafer, which is fixed within the wafer thinning carrier. Specifically, a wafer to be thinned is disposed in the receiving groove 11 of the carrier body 1, and the grinding device is capable of thinning the wafer. The wafer thinning apparatus also includes a bonding machine and a force sensing mechanism. The bonding machine is used to bond the wafer to the carrier body 1, so that the wafer is fixed in the receiving groove 11 of the carrier body 1. The force sensing mechanism is connected to the grinding mechanism and is at least used to detect changes in grinding force during the grinding process.

[0060] Example 6

[0061] like Figure 3 As shown, this embodiment provides a wafer thinning method, which specifically includes the following steps:

[0062] Provide a wafer thinning carrier as described in any of the above embodiments, and fix the wafer to be thinned in the receiving groove 11 of the wafer thinning carrier;

[0063] A wafer is provided, and a temporary bonding process is performed on the carrier body 1 and the wafer to fix the wafer to the carrier body 1. The wafer is then ground until the thickness of the wafer is reduced to a set thickness value.

[0064] Thinning the wafer to the pre-processing thickness refers to thinning the wafer, which has already been fixed to the carrier body 1, until the upper surface of the wafer is flush with the upper surface of the protrusion 12, and then simultaneously thinning both the wafer and the carrier body 1 to reduce the wafer to a set thickness. The set thickness is less than the depth of the receiving groove 11 of the carrier body 1.

[0065] Please see Figures 5-6As is easily understood, step a provides a carrier body 1 and a wafer, wherein a receiving groove 11 and a spacer groove are formed on the first surface of the carrier body 1. In step b, the carrier body 1 and the wafer are bonded. In this method, steps a, b, c, and d can be performed for thinning. First, as in step c, the wafer is thinned to a pre-processed thickness, and then as shown in step d, the wafer and the carrier body 1 are thinned, and the wafer is thinned to a set thickness.

[0066] Furthermore, the set thickness is 20µm to 60µm. Compared with the prior art, the wafer thinning method provided in this embodiment can thin the wafer and obtain a thinner wafer.

[0067] Furthermore, in this method, laser stripping, dry etching, or wet etching is used to perform grooving on the carrier body 1, and a receiving groove 11 is formed on the first surface of the carrier body 1.

[0068] Preferably, the carrier body 1 is circular, the transverse cross-section of the receiving groove 11 is circular, and the receiving groove 11 is concentrically arranged with the carrier body 1. After this grooving process, the receiving groove 11 and the edge of the annular protrusion formed around the receiving groove 11 are formed on the carrier body 1.

[0069] Furthermore, in this method, laser lift-off, dry etching, or wet etching processes are used to create spacer grooves on the edge of the annular protrusion of the carrier body 1, and multiple protrusions 12 spaced apart are formed on the first surface of the carrier body 1; the wafer is thinned by mechanical grinding. The wafer is thinned by mechanical grinding with a diamond grinding wheel, and the degree of wafer thinning can be fed back based on the force detection results during grinding.

[0070] Taking sapphire at 6nm as an example, with a grinding thickness of 50µm, the edge trapezoidal height is set to 75µm, which is 1.5 times the set thickness. Spacing grooves are opened on the edge of the annular protrusion of the carrier body 1 to form multiple spaced protrusions 12. The protrusions 12 are trapezoidal in shape, with an included angle of 35° between the two sides of the trapezoid and an interval angle of 10° between the trapezoids. When the feed speed is 1µm / s and the rotation speed is 1000rpm, the grinding force (vertical direction of the grinding surface) is maintained at 100N before grinding to the trapezoidal interface. When grinding to the trapezoidal interface, it is maintained at 100N just before contact. When it is fully in contact with the upper surface of the trapezoid, the force changes from 100N to 112N. Afterward, the stress gradually increases with the increase of grinding depth. When the thickness is 60µm, the grinding force is 118N. When the final thickness is 50µm, the grinding force increases and decreases to 134N.

[0071] Using the wafer thinning method provided by this invention, the protrusions 12 on the carrier body 1 can disperse the grinding stress, avoid wafer fragmentation during grinding, and improve the uniformity of the wafer after grinding. Furthermore, the protrusions 12 arranged circumferentially along the carrier body 1 can also play a role in monitoring the grinding thickness. During the process of grinding the wafer to the set thickness, especially when grinding the wafer from the pre-processing thickness to the set thickness, the grinding force will change, and the process can be predicted to be about to end based on the change in force. The wafers on the carrier body 1 are distributed in a trapezoidal shape, which can prevent large abrupt changes in stress during grinding. This can maintain the stability of the process, prevent sudden changes in the power of the grinding equipment, and avoid wafer fragmentation and uneven grinding.

[0072] Of course, wafers prepared by the wafer thinning method provided by this invention are also within the scope of protection of this invention.

[0073] Example 7

[0074] 1. A 152mm diameter accommodating groove is etched on a 159mm diameter round sapphire using a dry etching method. The height of the annular protrusion surrounding the accommodating groove is 30um, and the depth of the accommodating groove is 30um.

[0075] 2. Spacer grooves are formed on the edge of the annular protrusion of the carrier body using photolithography and etching, creating multiple spaced protrusions. Each protrusion is trapezoidal in shape, with a height of 30 μm, an included angle of 35° between its two sides, and a spacing angle of 10° between the trapezoids. Figure 6 The vehicle body shown in step a.

[0076] 3. Place the sapphire wafer to be bonded and the prepared bonding carrier body onto the bonding machine. The bonding temperature is 180℃, the bonding pressure is 20N, and the holding time is 150s. After bonding, as shown... Figure 6 As shown in step b.

[0077] 4. The bonded sapphire wafer is thinned using a diamond grinding wheel. The feed speed of the diamond grinding wheel is 1µm / s, the rotation speed is 1000rpm, and the set thickness of the thinned sapphire wafer is 20µm.

[0078] The wafer thinning process was repeated 100 times in this embodiment. During the thinning process, sapphire wafer fragmentation occurred a total of 7 times, and the sapphire wafer fragmentation rate was 7%.

[0079] Example 8

[0080] 1. A 152mm diameter accommodating groove is etched on a 159mm diameter round sapphire using a dry etching method. The height of the annular protrusion surrounding the accommodating groove is 45um, and the depth of the accommodating groove is 45um.

[0081] 2. By photolithography and etching, spacer grooves are formed on the edge of the annular protrusion of the carrier body to form multiple spaced protrusions. The protrusions are trapezoidal in shape, with a height of 45 μm, an included angle of 35° between the two sides of the trapezoid, and a spacing angle of 10° between the trapezoids.

[0082] 3. Place the sapphire wafer to be bonded and the processed bonding carrier body onto the bonding machine. The bonding temperature is 180℃, the bonding pressure is 20N, and the holding time is 150s.

[0083] 4. The bonded sapphire wafer is thinned using a diamond grinding wheel. The feed speed of the diamond grinding wheel is hm / s, the rotation speed is 1000rpm, and the set thickness of the thinned sapphire wafer is 30um.

[0084] The difference between this embodiment and embodiment 7 is that the set thickness of the sapphire wafer to be thinned is 30um, and the depth of the receiving groove of the wafer thinning carrier is 45um.

[0085] The wafer thinning process was repeated 100 times in this embodiment. Sapphire wafer fragmentation occurred a total of 5 times during the thinning process, and the sapphire wafer fragmentation rate was 5%.

[0086] Example 9

[0087] 1. A 152mm diameter accommodating groove is etched on a 159mm diameter round sapphire using a dry etching method. The height of the annular protrusion surrounding the accommodating groove is 75um, and the depth of the accommodating groove is 75um.

[0088] 2. By photolithography and etching, spacer grooves are formed on the edge of the annular protrusion of the carrier body to form multiple spaced protrusions. The protrusions are trapezoidal in shape, with a height of 75 μm, an included angle of 35° between the two sides of the trapezoid, and a spacing angle of 10° between the trapezoids.

[0089] 3. Place the sapphire wafer to be bonded and the processed bonding carrier body onto the bonding machine. The bonding temperature is 180℃, the bonding pressure is 20N, and the holding time is 150s.

[0090] 4. The bonded sapphire wafer is thinned using a diamond grinding wheel. The feed speed of the diamond grinding wheel is 1µm / s, the rotation speed is 1000rpm, and the set thickness of the thinned sapphire wafer is 60µm.

[0091] The difference between this embodiment and embodiment 7 is that the set thickness of the sapphire wafer to be thinned is 60um, and the depth of the receiving groove of the wafer thinning carrier is 75um.

[0092] The wafer was thinned by repeating the steps in this embodiment 100 times. Sapphire wafer fragmentation occurred twice during the thinning process, and the sapphire wafer fragmentation rate was 2%.

[0093] Comparative Example 1

[0094] In this embodiment, a wafer thinning method commonly used in the art is employed:

[0095] 1. A 152mm diameter accommodating groove is etched on a 159mm diameter round sapphire using a dry etching method. The height of the annular protrusion surrounding the accommodating groove is 28um, and the depth of the accommodating groove is 28um.

[0096] 2. Place the sapphire wafer to be bonded and the processed bonding carrier body onto the bonding machine. The bonding temperature is 180℃, the bonding pressure is 20N, and the holding time is 150s.

[0097] 3. A diamond grinding wheel is used to thin the bonded sapphire wafer. The feed rate of the diamond grinding wheel is 1µm / s, the rotation speed is 1000rpm, and the set thickness of the thinned sapphire wafer is 30µm. During this thinning process, the diamond grinding wheel does not come into contact with the carrier body.

[0098] The difference between this embodiment and embodiment 8 is that this embodiment uses a wafer thinning method commonly used in the art. Specifically, in common practice, only the wafer to be thinned is thinned, and the depth of the receiving groove for accommodating the sapphire wafer on the wafer thinning carrier is less than the set thickness.

[0099] The wafer was thinned by repeating the steps in this embodiment 100 times. During the thinning process, sapphire wafer fragmentation occurred a total of 47 times, and the sapphire wafer fragmentation rate was 47%.

[0100] Compared to Example 8, Comparative Example 1 shows a higher fragmentation rate when using conventional methods for wafer thinning operations with the same thickness setting. However, the wafer thinning carrier and wafer thinning method provided in this application not only result in thinner wafers but also achieve a lower wafer fragmentation rate during the thinning process, thus avoiding processing losses.

[0101] Comparative Example 2

[0102] In this embodiment, the wafer thinning method provided by the present invention is used:

[0103] 1. A 152mm diameter accommodating groove is etched on a 159mm diameter round sapphire using a dry etching method. The height of the annular protrusion surrounding the accommodating groove is 60um, and the depth of the accommodating groove is 60um.

[0104] 2. By photolithography and etching, spacer grooves are formed on the edge of the annular protrusion of the carrier body to form multiple spaced protrusions. The protrusions are trapezoidal in shape, with the included angle between the two sides of the trapezoid being 35°, the spacing angle between the trapezoids being 10°, and the height of the trapezoids being 60µm, which is twice the set thickness.

[0105] 3. Place the sapphire wafer to be bonded and the processed bonding carrier body onto the bonding machine. The bonding temperature is 180℃, the bonding pressure is 20N, and the holding time is 150s.

[0106] 4. A diamond grinding wheel is used to thin the bonded sapphire wafer. The feed speed of the diamond grinding wheel is 1µm / s, the rotation speed is 1000rpm, and the set thickness of the thinned sapphire wafer is 30µm. During this thinning process, the diamond grinding wheel does not come into contact with the carrier body.

[0107] The wafer was thinned by repeating the steps in this embodiment 100 times. During the thinning process, sapphire wafer fragmentation occurred a total of 17 times, and the sapphire wafer fragmentation rate was 17%.

[0108] Compared to Example 8, the height of the protrusion in this comparative example is twice the set thickness, resulting in a higher fragmentation rate during processing. However, when the height of the protrusion is 1.5 times the set thickness, not only can a thinner wafer be obtained, but the wafer fragmentation rate is also lower during the thinning process.

[0109] Comparative Example 3

[0110] In this embodiment, the wafer thinning method provided by the present invention is used:

[0111] 1. A 152mm diameter accommodating groove is etched on a 159mm diameter round sapphire using a dry etching method. The height of the annular protrusion formed around the accommodating groove is 45um, and the depth of the accommodating groove is 45um, which is twice the set thickness.

[0112] 2. By photolithography and etching, spacer grooves are formed on the edge of the annular protrusion of the carrier body to form multiple spaced protrusions. The protrusions are triangular, with the included angle between the two sides of the triangle being 35°, the spacing angle between the triangles being 10°, and the height of the triangle being 30µm.

[0113] 3. Place the sapphire wafer to be bonded and the processed bonding carrier body onto the bonding machine. The bonding temperature is 180℃, the bonding pressure is 20N, and the holding time is 150s.

[0114] 3. A diamond grinding wheel is used to thin the bonded sapphire wafer. The feed rate of the diamond grinding wheel is 1µm / s, the rotation speed is 1000rpm, and the set thickness of the thinned sapphire wafer is 30µm. During this thinning process, the diamond grinding wheel does not come into contact with the carrier body.

[0115] The wafer was thinned by repeating the steps in this embodiment 100 times. During the thinning process, sapphire wafer fragmentation occurred a total of 26 times, and the sapphire wafer fragmentation rate was 26%.

[0116] Compared with Example 8, the difference in this comparative example is that the protrusion is set in a triangular shape. Since the contact area is small and the contact stress is large when grinding reaches the upper surface of the triangle, the risk of edge fragmentation during grinding increases. Therefore, in a preferred embodiment, the protrusion is trapezoidal.

[0117] Furthermore, comparing this comparative example with Comparative Example 1, under the same set thickness of the thinned sapphire wafer, although the protrusion of this comparative example is triangular, its fragmentation rate is still lower than that of the conventional method. It can be seen that the wafer thinning carrier provided by the present invention can significantly reduce the wafer fragmentation rate in the wafer thinning process.

[0118] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A wafer thinning method, characterized in that, include: A grinding mechanism and a wafer thinning carrier are provided. The wafer thinning carrier includes a carrier body (1), a receiving groove (11), and a plurality of protrusions (12). The carrier body (1) has a first side and a second side facing away from each other. The receiving groove (11) is formed on the first side of the carrier body (1) and is used to receive a wafer. The plurality of protrusions (12) are spaced apart on the first side of the carrier body (1) and distributed around the receiving groove (11). The wafer to be thinned is fixed in the receiving groove (11) of the wafer thinning carrier, and then the wafer and the protrusion (12) are ground. During the grinding process, the magnitude of the grinding force is continuously monitored, and when the grinding force reaches the preset threshold, it is determined that the thickness of the wafer has reached the set thickness value. The size of the protrusion (12) in the first direction gradually decreases along the second direction. The first direction is parallel to the first surface of the vehicle body (1), and the second direction is perpendicular to the first direction and gradually moves away from the vehicle body (1). The protrusion (12) is trapezoidal; The carrier body (1) is made of any one of sapphire, SiC or Si. The receiving groove (11) is circular, and a plurality of the protrusions (12) are evenly distributed on the edge of the receiving groove (11), and the central angle corresponding to each protrusion (12) is 30°~45°.

2. The wafer thinning method according to claim 1, characterized in that: The height of the protrusion (12) is greater than the thickness of the wafer.

3. The wafer thinning method according to claim 1, characterized in that... The sum of the depth of the receiving groove (11) and the height of the protrusion (12) is less than or equal to the thickness of the wafer, and the depth of the receiving groove (11) is greater than the thickness of the wafer thinned to a set thickness value.

4. The wafer thinning method according to claim 1, characterized in that: The grinding mechanism is connected to the force sensing mechanism, which is used at least to detect changes in the grinding force during the grinding process.

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