Device and Method for Double-Side Thinning

Abstract

The present invention discloses a device and method for double-sided thinning. The device includes: an annular retainer, which includes a carrier ring and a hydrostatic pressure ring. The carrier ring radially supports the outer peripheral side of the workpiece to be processed, and drives the workpiece to be processed to rotate in the vertical direction through the carrier ring. The hydrostatic pressure ring is fixedly arranged on the outer peripheral side of the carrier ring along the radial direction; two hydrostatic pads, namely a first hydrostatic pad and a second hydrostatic pad, which are symmetrically arranged on both sides of the annular retainer respectively; a feed shaft, which is arranged at the lower opening of the hydrostatic pad and moves along the axial direction. The grinding wheel on the feed shaft directly grinds the workpiece to be processed through the opening. The distance between the first hydrostatic pad and the second hydrostatic pad is D0 + 130 to D0 + 150 microns. Thus, the use of this device can relatively improve the production stability and reduce the frequency of machine tool debugging.

Description

Technical Field

[0001] The present invention belongs to the technical field of thinning devices, and particularly relates to a device and method for double-sided thinning. Background Art

[0002] Double-sided thinning is used to uniformly remove the damaged layer caused by multi-wire cutting after normal multi-wire cutting is used.

[0003] Currently, the DXSG320 machine is a commonly used double-sided thinning device. First, the workpiece to be processed is placed on the carrier ring. The rotation of the carrier ring drives the rotation of the workpiece. The grinding wheel arranged on the advancing shaft grinds both sides of the silicon wafer. During the thinning process, in the limited space of the grinding chamber, it is inevitable that the workpiece will have a certain yaw during the axial rotation in the vertical direction. In the case of a large yaw, the workpiece will be severely warped and deformed, affecting the nano-topography of the product in subsequent processes. During the production process, it is necessary to continuously adjust the yaw position of the grinding wheel to ensure the stability of the product quality.

[0004] Since the interval between the two opposite static pressure pads directly affects the space of the grinding chamber. To control the parallelism and yaw amount of each component in the grinding chamber, it is necessary to adjust the space of the grinding chamber according to the workpieces processed under different process conditions to improve the stability of the process.

[0005] In this regard, the existing double-sided thinning devices and process methods need to be further improved. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems in the related art to some extent. For this purpose, the object of the present invention is to provide a device and method for double-sided thinning, which can broaden the range of production conditions, relatively improve the production stability of the equipment, reduce the modulation frequency of the machine, and improve the stability of the product quality without changing the main hardware structure of the device.

[0007] In one aspect of the present invention, a device for double-sided thinning is provided. According to an embodiment of the present invention, the device includes:

[0008] A ring-shaped retainer, the ring-shaped retainer includes a carrier ring and a static pressure ring. The carrier ring radially supports the outer peripheral side of the workpiece to be processed, and drives the workpiece to be processed to rotate axially in the vertical direction through the carrier ring. The static pressure ring is fixedly arranged on the outer peripheral side of the carrier ring along the radial direction.

[0009] Two static pressure pads, namely a first static pressure pad and a second static pressure pad. The two static pressure pads are respectively symmetrically arranged on both sides of the ring-shaped retainer.

[0010] An advancing shaft, the advancing shaft is arranged at the lower opening of the static pressure pad and moves along the axial direction. The grinding wheel on the advancing shaft directly grinds the workpiece to be processed through the opening.

[0011] The distance between the first static pressure pad and the second static pressure pad is D 0 +130 to D 0 +150 microns, where D 0 is the initial thickness of the workpiece to be processed, in microns

[0012] The purpose of the present invention is to further improve the stability and parallelism of the double-sided thinning device on the premise of broadening the range of production conditions. Among them, the degree of freedom of the workpiece to be processed in the grinding chamber has the greatest influence on it, and the gap between the two static pressure pads directly affects the degree of freedom of the workpiece to be processed. The inventor found in actual operation that when the yaw space is too small, the degree of freedom of the workpiece to be processed is small, resulting in a small yaw space of the workpiece to be processed. When the yaw amplitude of the grinding wheel is adjusted to be greater than the yaw space of the workpiece to be processed, the yaw of the grinding wheel is likely to cause extrusion of the workpiece to be processed, making the grinding conditions unstable or the nano-topography poor; when the yaw space is too large, the degree of freedom of the workpiece to be processed is large, resulting in the yaw space of the processing tool being much larger than the adjustable yaw amplitude of the equipment grinding wheel, resulting in an additional yaw space for the workpiece to be processed during processing, and the yaw of the workpiece to be processed will make the grinding conditions unstable or the nano-topography poor

[0013] In the hardware main structure of the double-sided thinning device of the present invention, the upper limit of the adjustment of the grinding wheel parameters is 50 microns. If it is greater than 50 microns, the origin needs to be reset before further adjustment, increasing the commissioning frequency of the machine tool and making the grinding conditions unstable. Therefore, the upper limit of the yaw amount of the static pressure ring is set to 50 microns as the condition for its maximum degree of freedom. Through a large number of experiments, it is found that the lower limit of the yaw amount of the static pressure ring is 40 microns. If it is less than 40 microns, the phenomenon of workpiece extrusion often occurs due to the small yaw amount

[0014] During the working process of the double-sided thinning device of the present invention, the workpiece to be processed is always in a rotating state along the axial direction. Considering that the yaw of the static pressure ring will directly affect the yaw of the workpiece to be processed. Through a large number of experiments, it is found that when the yaw amount of the static pressure ring is 40 - 50 microns, it will cause synchronous yaw of the workpiece to be processed. The yaw amount is 35 - 45 microns. Considering the requirement that the TTV of the pre-workpiece is within 30 microns, and considering that there is yaw on both sides during the rotation process, therefore, the total yaw amount of the workpiece to be processed is 100 - 120 microns (i.e., ((35 - 45)+30 / 2)*2). In order to control the total yaw amount of the workpiece to be processed to be 100 - 120 microns as required, considering the requirement that the flatness of the surface of the static pressure pad is below 30 microns, so the distance between the first static pressure pad and the second static pressure pad is controlled to be the total yaw amount of the workpiece to be processed + 30 microns + D 0 That is, the distance between the first static pressure pad and the second static pressure pad is D 0 +130 microns to D 0 +150 microns, where D 0 is the initial thickness of the workpiece to be processed, in microns

[0015] Flatness is the deviation of the macroscopic uneven height relative to the ideal plane. The flatness of the surface of the hydrostatic pad is related to the material it uses. Generally, materials similar to metal coating can be used, or ceramic materials can also be used, and their flatness can reach below 30 microns. Especially when using ceramic materials, the flatness can reach below 5 microns.

[0016] In addition, the double-sided thinning device according to the above embodiments of the present invention may further have the following additional technical features:

[0017] In some embodiments of the present invention, the thickness of the hydrostatic ring is set to D 0 +(130 - 150) microns + 2X - (40 - 50) microns, where X is the reserved interval for the operation of the hydrostatic pad and the hydrostatic ring, and the unit is micron.

[0018] In order to further improve the stability and parallelism during the operation of the double-sided thinning device, the inventor further explored and studied and found that during the operation of the double-sided thinning device, the processed workpiece and the carrier ring are integrated and rotate axially in the vertical direction. The carrier ring and the hydrostatic ring are in direct contact. When the distance between the first hydrostatic pad and the second hydrostatic pad is kept constant, if the thickness of the hydrostatic ring is too large, the gap between the hydrostatic ring and the hydrostatic pad will be too small. If the gap is less than the basic yaw amount during the rotation of the hydrostatic ring, it will cause jamming during rotation and normal production cannot be carried out; if the thickness of the hydrostatic ring is too small, the gap between the hydrostatic ring and the hydrostatic pad will be too large. If the gap is greater than the distance between the workpiece and the hydrostatic pad, it will cause the workpiece to contact the hydrostatic pad during grinding, resulting in additional yaw of the workpiece and unstable continuous production, causing instability in the quality of the processed workpiece. Based on recognizing the above impacts and combining the above experimental results that the yaw amount of the hydrostatic ring is 40 - 50 microns, the inventor obtained that the thickness H2 of the hydrostatic ring is the distance between the two hydrostatic pads + 2X - the yaw amount of the hydrostatic ring, that is, D 0 +(130 - 150) microns + 2X - (40 - 50) microns, where X is the reserved interval for the operation of the hydrostatic pad and the hydrostatic ring, and this reserved interval is controlled by the hardware structure of the double-sided thinning device itself. The general value range of X is 20 - 30 microns.

[0019] In the embodiments of the present invention, a positioning groove driving piece is provided on the carrier ring. The positioning groove driving piece is separated from the carrier ring. The processed workpiece is directly clamped on the positioning groove driving piece, and the positioning groove driving piece rotates to drive the processed workpiece to rotate.

[0020] In the embodiments of the present invention, the thickness of the positioning groove driving piece in the grinding area is D 1 -80 - D 1 -100 microns, and the thickness of the positioning groove driving piece outside the grinding area is greater than the thickness in the grinding area, where D 1The final thickness of the workpiece to be processed, with the unit of micrometer.

[0021] In an embodiment of the present invention, a positioning groove driving piece is arranged on the bearing ring. The positioning groove driving piece is in the same plane as the bearing ring. The workpiece to be processed is directly clamped on the bearing ring, and the rotation of the whole workpiece is driven by the movement of the driving point of the positioning groove driving piece on the bearing ring.

[0022] In an embodiment of the present invention, contact rollers are arranged at the bottom of the outer periphery of the static pressure ring and two static pressure guide wheels are arranged at the upper part. Water is input through the water inlet of the static pressure guide wheel, and pressure is generated by the water to press and clamp the static pressure ring for fixation.

[0023] In still another aspect of the present invention, a method for thinning using the above-mentioned double-sided thinning device is proposed. According to an embodiment of the present invention, the method includes:

[0024] (1) Grinding wheel approaching stage: Initially, the interval of the grinding wheel is set to the initial thickness of the workpiece;

[0025] (2) Rough machining stage: The purpose is to remove the damaged layer caused by multi-wire cutting. The removal amount in the rough machining stage is determined by the cutting conditions;

[0026] (3) Finishing machining stage: The removal amount in the finishing machining stage is determined according to the situation in the rough machining stage, generally being 15 - 25 micrometers;

[0027] (4) Trimming and thinning stage: The removal amount in the trimming and thinning stage is 0 - 5 micrometers;

[0028] Wherein, before step (1), the distance between the two static pressure pads is set to D 0 +130 to D 0 +150 micrometers, where D 0 is the initial thickness of the workpiece to be processed, with the unit of micrometer.

[0029] In addition, the double-sided thinning method according to the above embodiment of the present invention may further have the following additional technical features:

[0030] In an embodiment of the present invention, before the step (1), the thickness of the static pressure ring is set to D 0 +(130 - 150) micrometers + 2X - (40 - 50) micrometers, where X is the reserved interval between the static pressure pad and the static pressure ring, with the unit of micrometer.

[0031] In an embodiment of the present invention, before the step (1), the thickness of the fixed groove driving piece in the grinding area is set to D 1 -80 to D 1 -100 micrometers, and the thickness of the positioning groove driving piece outside the grinding area is greater than the thickness in the grinding area, where D 1is the final thickness of the workpiece to be processed, in micrometers.

[0032] In an embodiment of the present invention, two contact rollers are arranged at the bottom of the hydrostatic ring and two hydrostatic guide wheels are arranged at the upper part. Water pressure is applied through the water inlet of the hydrostatic guide wheel to form a water film on the hydrostatic ring, and the hydrostatic ring is pressurized and fixed by the pressure generated by the water film.

[0033] In the process method of double-sided thinning of the present invention, step (5) is also included: the step of clamping the workpiece to be processed.

[0034] The water inlet continuously sprays water onto a hydrostatic pad, so that the workpiece to be processed is pushed towards the other hydrostatic pad under the action of water pressure, and then the workpiece placed on one hydrostatic pad is adsorbed by the suction cup on the robotic arm, such as adsorbing the workpiece with a hard suction cup.

[0035] In an embodiment of the present invention, by adjusting the software to increase the water spraying time, the workpiece to be processed is placed on one hydrostatic pad to replace directly vacuum-adsorbing the workpiece, and a soft material with a thickness of 1-3 micrometers is provided on the surface of the hard suction cup in contact with the workpiece, or a soft material is arranged on the entire surface of the hard suction cup in contact with the workpiece.

[0036] The additional aspects and advantages of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0038] Figure 1 is a schematic longitudinal sectional structure view of a double-sided thinning device according to an embodiment of the present invention;

[0039] Figure 2 is Figure 1 a partial structure view of the hydrostatic pad, grinding wheel and workpiece in

[0040] Figure 3 a is a left view of a carrier ring in a double-sided thinning device according to another embodiment of the present invention;

[0041] Figure 3 b is a left view of a carrier ring in a double-sided thinning device according to another embodiment of the present invention;

[0042] Figure 4 a is Figure 3 a schematic structural view of a positioning groove driving piece in the carrier ring in a;

[0043] Figure 4 b is Figure 3Another structural schematic diagram of the positioning groove driving piece in the bearing ring in a

[0044] Figure 5 It is a structural schematic diagram of the static pressure pad in the double-sided thinning device according to another embodiment of the present invention;

[0045] Figure 6 It is a working structural schematic diagram of the annular retainer and the roller in the double-sided thinning device according to another embodiment of the present invention;

[0046] Figure 7 It is a structural schematic diagram of the hard chuck in the double-sided thinning device according to another embodiment of the present invention;

[0047] Figure 8 It is a structural schematic diagram of the hard chuck in the double-sided thinning device according to another embodiment of the present invention;

[0048] Figure 9 It is a flowchart of the double-sided thinning method of the present invention.

[0049] Wherein, 100 - annular retainer, 200 - first static pressure pad, 300 - second static pressure pad, 400 - grinding wheel, 500 - hard chuck, 11 - static pressure ring, 12 - bearing ring, 13 - workpiece to be processed, 111 - contact roller, 112 - static pressure guide wheel, 121 - positioning groove driving piece, 122 - driving point, 21 - water supply hole, 51 - soft material, 600 - advancing shaft. Detailed implementation manners

[0050] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0051] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0053] In the present invention, unless otherwise clearly specified and limited, the terms such as "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] In the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0055] In one aspect of the present invention, the present invention provides a device for double-sided thinning.

[0056] According to an embodiment of the present invention, referring to Figure 1 、 2 , the double-sided thinning device of the present invention includes an annular retainer 100, two hydrostatic pads 200 / 300, and a feed shaft 600 provided with a grinding wheel 400. The annular retainer 100 includes a hydrostatic ring 11 and a carrier ring 12. The carrier ring 12 radially supports the outer peripheral side of the workpiece 13 to be processed, and drives the workpiece 13 to rotate axially in the vertical direction through the carrier ring 12. The hydrostatic ring 11 is fixedly arranged on the outer peripheral side of the carrier ring 12 along the radial direction; the two hydrostatic pads are respectively a first hydrostatic pad 200 and a second hydrostatic pad 300, and the two hydrostatic pads are symmetrically arranged on both sides of the annular retainer 100; at the lower openings (not shown) of the two hydrostatic pads 200 / 300, the feed shaft 600 moves along the axial direction, and the grinding wheel 400 on the feed shaft 600 directly grinds the workpiece 13 through the openings. In the present invention, the driving manner of the carrier ring 12 is not limited as long as the carrier ring 12 can be rotated in the vertical direction.

[0057] On the premise of broadening the range of production conditions, to improve the stability and parallelism of the double-sided thinning device of the present invention, among which the degree of freedom of the workpiece being processed in the grinding chamber has the greatest influence, and the distance between the two hydrostatic pads directly affects the degree of freedom of the workpiece 13 being processed.

[0058] During the operation of the double-sided thinning device of the present invention, the workpiece 13 being processed rotates axially in the vertical direction. Considering that the yaw of the hydrostatic ring 11 will directly affect the yaw of the workpiece 13 being processed. Through a large number of experiments, it is found that when the yaw amount of the hydrostatic ring 11 is 40-50 microns, it will cause the synchronous yaw of the workpiece being processed, and the yaw amount is 35-45 microns. In order to meet the requirement that the TTV of the pre-workpiece is within 30 microns, and considering that there is yaw on both sides during the rotation process, therefore, the total yaw amount of the workpiece being processed is 100-120 microns (i.e., ((35-45)+30 / 2)*2). To control the total yaw amount of the workpiece being processed to be 100-120 microns, considering the requirement that the flatness of the surface of the hydrostatic pad is below 30 microns, so the distance between the first hydrostatic pad and the second hydrostatic pad is controlled to be the total yaw amount of the workpiece being processed + 30 microns + D 0 , that is, the distance H1 between the first hydrostatic pad and the second hydrostatic pad is D 0 +130 microns to D 0 +150 microns, where D 0 is the initial thickness of the workpiece being processed, in microns. See specifically Figure 1 as shown.

[0059] In order to further improve the stability and parallelism during the rotation of the double-sided thinning device, the inventor further explored and found that during the operation of the double-sided thinning device, the workpiece 13 being processed and the carrier ring 12 are integrated and rotate axially in the vertical direction. The carrier ring 12 and the hydrostatic ring 11 are in direct contact. When the distance between the first hydrostatic pad 200 and the second hydrostatic pad 300 is kept constant, if the thickness of the hydrostatic ring 11 is too large, the gap between the hydrostatic ring 11 and the hydrostatic pads 200 / 300 will be too small. If the gap is less than the yaw amount of the basic hydrostatic ring 11 during rotation, it will cause jamming during rotation and normal production cannot be carried out; if the thickness of the hydrostatic ring 11 is too small, the gap between the hydrostatic ring 11 and the hydrostatic pads 200 / 300 will be too large. If the gap is greater than the distance between the workpiece 13 and the hydrostatic pads 200 / 300, it will cause the workpiece to contact the hydrostatic pads during grinding, resulting in additional yaw of the workpiece being processed and unstable continuous production, and the quality of the workpiece being processed is unstable. Based on recognizing the above effects, and combining the yaw amount of the hydrostatic ring 11 being 40-50 microns, the inventor obtained that the thickness H2 of the hydrostatic ring 11 as shown in Figure 1 is the distance between the first hydrostatic pad 200 and the second hydrostatic pad 300 + 2X - the yaw amount of the hydrostatic ring, that is, D 0+(130 - 150) microns + 2X - (40 - 50) microns, where X is the reserved interval between the hydrostatic pad 200 / 300 and the hydrostatic ring 11, and this reserved interval is controlled by the thinning machine tool hardware structure itself. The general value range of X is 20 - 30 microns.

[0060] In order to achieve the axial self-rotation of the carrier ring in the vertical direction, as Figure 3 shown in a, a positioning groove driving piece 121 is provided on the carrier ring 12. The positioning groove driving piece 121 is separated from the carrier ring 12. A groove (not shown) is correspondingly provided on the outer circumference of the workpiece 13 to be processed. The positioning groove driving piece 121 on the carrier ring 12 is directly clamped on the groove, and the rotation of the positioning groove driving piece 121 drives the workpiece 13 to rotate. For example, an internal gear can be provided on the inner circumferential surface of the carrier ring 12, and the driving gear connected to the motor meshes with the internal gear. That is, under the action of the motor, the internal gear is driven to rotate by the driving gear, thereby driving the carrier ring 12 to rotate, and then driving the workpiece 13 to axially self-rotate through the positioning groove driving piece 121.

[0061] As Figures 2-4 shown, during the grinding process of the double-sided thinning device of the present invention, as the workpiece 13 axially rotates, a part of the positioning groove driving piece 121 will enter the grinding area of the grinding wheel when it rotates. Therefore, the part in contact with the grinding area of the grinding wheel is defined as the grinding area of the positioning groove driving piece 121.

[0062] The inventor found that driving the entire workpiece 13 to rotate through the positioning groove driving piece 121 on the carrier ring 12 requires that the grinding wheel 400 does not contact the positioning groove driving piece 121. Otherwise, it will cause the yaw of the workpiece 13 and the thickness of the edge of the workpiece 13 will be uneven. To meet the stability requirements of the equipment operation, under the condition of meeting the above thickness design requirements of the hydrostatic ring 11 and in cooperation with the final thickness requirements of the workpiece, considering that the hydrostatic ring 11 has a yaw amount of 40 - 50 microns, the thickness of the positioning groove driving piece 121 in the grinding area is D 1 -(40 - 50)*2 microns, that is, D 1 -80 - D 1 -100 microns, where D 1 is the final thickness of the workpiece, in microns. In this way, during the operation process, the grinding wheel 400 will not contact the positioning groove driving piece 121, effectively avoiding the distortion of the positioning groove driving piece 121 caused by the grinding wheel resistance. As Figure 3 a and Figure 3 b, the M area is the grinding area of the positioning groove driving piece 121.

[0063] In order to further reduce the space in which the static pressure ring 12 can swing and avoid the distortion of the positioning groove driving piece 121 during operation, it is designed that the thickness of the positioning groove driving piece 121 outside the grinding area is greater than that in the grinding area. That is, by increasing the thickness of the positioning groove driving piece 121 outside the grinding area, its bending strength is enhanced and the distortion of the positioning groove driving piece 121 is reduced. As Figure 4 shown in a, the structures of three different positioning groove driving pieces 121 all meet the requirement that the thickness outside the grinding area is greater than that in the grinding area. As Figure 4 shown in b, it is designed that the grinding area of the positioning groove driving piece 121 reaches the thickened part outside the grinding area through the N area, which not only reduces the distortion of the positioning groove driving piece 121 and enhances its bending strength, but also avoids the grinding wheel 400 contacting the positioning groove driving piece 121 at the junction area (the junction between the grinding area and the area outside the grinding area). For the specific junction area, refer to Figure 4 b. Since a part of the positioning groove driving piece 121 will enter the grinding area, it is required to use a plastic material with good toughness and high hardness, such as polyimide, carbon fiber or a material combined with both.

[0064] In order to avoid the distortion of the positioning groove driving piece 121 during operation, another solution that can be adopted is to refer to Figure 3 b. The positioning groove driving piece 121 is arranged on the bearing ring 12. The positioning groove driving piece 121 and the bearing ring 12 are in the same plane. The driving point 122 of the positioning groove driving piece 121 is directly stuck on the workpiece 13 to be processed. Through the rotation of the driving point 122 of the positioning groove driving piece 121 on the bearing ring 12, the rotation of the entire workpiece 13 to be processed is driven.

[0065] Furthermore, the inventor found that in the existing fixed method using the contact roller 111, the static pressure ring is fixed by directly contacting and pressing the outer periphery of the static pressure ring through the roller. Due to long-term extrusion, the roller bearing wears and gaps appear, resulting in the swing of the static pressure ring. As Figure 6 shown, the contact roller 111 and the static pressure guide wheel 112 are arranged at the bottom of the static pressure ring 11. Two contact rollers 111 are arranged at the bottom of the static pressure ring 11, and the static pressure ring 11 is carried and fixed through the contact of the contact rollers 111; the static pressure guide wheel 112 forms a water film between its outer peripheral surface and the static pressure ring 11 through the input water to generate water pressure to press and fix the static pressure ring 11. This fixed method is called the static pressure water seal type for fixing the static pressure ring. In this embodiment, a combination of the roller contact fixing method and the static pressure water seal fixing method is used to fix the static pressure ring. On the one hand, it avoids the situation that it is difficult to achieve a stable fixing effect only relying on the water pressure generated by the water inlet. On the other hand, even if gaps appear due to the wear of the rollers caused by long-term extrusion, resulting in swing, under the action of gravity, the entire annular retainer 100 will automatically move downward, relatively improving the production stability.

[0066] In the second aspect of the present invention, the present invention proposes a process method for double-sided thinning by using the above double-sided thinning device. Refer toFigure 9 , the process method of this embodiment includes:

[0067] S100: Grinding wheel approaching stage, making the grinding wheel approach the surface of the workpiece 13;

[0068] In this step, the workpiece is installed in the conventional operation mode, and then by setting the control program on the double-sided thinning device, the grinding wheel 400 is made to approach the surface of the workpiece. The distance between the two grinding wheels 400 is set to the maximum thickness of the surface of the workpiece 13 before thinning, so that the grinding wheel 400 can directly contact the surface of the workpiece 13 when it starts to run, improving work efficiency. It should be noted that the control program on the double-sided thinning device is a conventional component of the device and will not be elaborated here.

[0069] S200: Rough machining stage, setting the rough machining removal amount of the grinding wheel 400 to rough machine the surface of the workpiece;

[0070] In this step, by setting the control program on the double-sided thinning device, the rough machining removal amount of the grinding wheel 400 is set, and then the grinding wheel 400 is turned on to rough machine the surface of the workpiece 13. Specifically, the value of the set rough machining removal amount is the thickness of the damaged layer caused by multi-wire cutting, with the aim of removing the thickness in a relatively short time. Here, the rough machining removal amount is determined in combination with the cutting conditions. For example, when using a cutting wire of 0.16 microns and producing with GC#1000, the rough machining removal amount is about 50 - 60 microns; with GC#1200, the rough machining removal amount is about 40 - 50 microns; with GC#1500, the rough machining removal amount is about 35 - 45 microns. Among them, 1000, 1200, and 1500 are mesh numbers. The larger the mesh number, the smaller the particles, and GC represents silicon carbide.

[0071] S300: Fine machining stage, setting the fine machining removal amount of the grinding wheel 400 to fine machine the surface of the workpiece 13 after rough machining;

[0072] In this step, by setting the control program on the double-sided thinning device, the fine machining removal amount of the grinding wheel 400 is set to fine machine the surface of the workpiece 13 after rough machining. Specifically, the set value of the fine machining removal amount in this application is the final thickness of the workpiece after thinning plus the subsequent trimming removal amount. Here, the removal amount is about (15 - 25) microns

[0073] S400: Trimming and thinning stage, trimming the surface of the workpiece 13 after fine machining.

[0074] In this step, by setting the control program on the double-sided thinning device, the trimming removal amount of the grinding wheel 400 is set to trim the workpiece 13 after fine machining. Specifically, the set value of the trimming removal amount is 0 - 5 microns.

[0075] Before the steps of the implemented double-sided thinning process method, set the distance between the two hydrostatic pads to be D0 + 130 to D0 + 150 microns, where D 0 is the initial thickness of the workpiece 13 to be processed, in microns. Without changing the main structure of the hardware, the gap between the two hydrostatic pads 200 / 300 directly affects the degree of freedom of the workpiece 13 to be processed. To improve the stability during the production of the double-sided thinning device, adjust the distance between the two hydrostatic pads according to the above requirements. For specific details, refer to the part of the double-sided thinning device.

[0076] In the embodiment of the double-sided thinning method, to further improve the production stability and reduce the machine setup frequency, it is required that the distance between the two hydrostatic pads satisfies D 0 + 130 to D 0 + 150 microns, and combined with the yaw amount of the hydrostatic ring 11 being 40 to 50 microns, as shown in Figure 1 the thickness H2 of the hydrostatic ring 11 is the distance between the two hydrostatic pads 200 / 300 + 2X - the yaw amount of the hydrostatic ring, that is, D 0 + (130 - 150) microns + 2X - (40 - 50) microns, where X is the reserved interval between the hydrostatic pads 200 / 300 and the hydrostatic ring 11 during operation. This reserved interval is controlled by the hardware structure of the thinning machine itself, and the value range of X is 20 to 30 microns.

[0077] In the embodiment of the double-sided thinning method, to meet the requirements of equipment operation stability and parallelism, under the condition of meeting the above design requirements for the thickness of the hydrostatic ring 11, and combined with the final thickness requirement of the workpiece to be processed, considering the 40 - 50 micron yaw amount of the hydrostatic ring, the thickness of the positioning groove driving piece 121 in the grinding area is D 1 - (40 - 50) * 2 microns, that is, D 1 - 80 to D 1 - 100 microns, where D 1 is the final thickness of the workpiece to be processed, in microns. In this way, during the grinding operation process, the grinding wheel 400 will not contact the positioning groove driving piece 121, effectively avoiding the distortion of the positioning groove driving piece 121 caused by the resistance of the grinding wheel 400.

[0078] To further reduce the yaw space of the hydrostatic ring 12 and avoid the distortion of the positioning groove driving piece 121 during operation, design the thickness of the positioning groove driving piece 121 outside the grinding area to be greater than the thickness in the grinding area, that is, by increasing the thickness of the positioning groove driving piece 121 outside the grinding area to enhance its bending strength.

[0079] To avoid the distortion of the positioning groove driving piece 121 during operation, another solution that can be adopted is to refer to Figure 3b. A positioning groove driving piece 121 is arranged on the bearing ring 12. The positioning groove driving piece 121 and the bearing ring 12 are in the same plane. The driving point 122 arranged on the positioning groove driving piece 121 is directly clamped on the corresponding groove of the workpiece 13 to be processed. By the rotation of the driving point 122 on the positioning groove driving piece 121 on the bearing ring 12, the rotation of the entire workpiece 13 to be processed is driven.

[0080] In the embodiment of the double-sided thinning method, the inventor found that in the prior art, the static pressure ring is fixed by directly contacting and pressing the outer periphery of the static pressure ring by a roller in a roller contact fixing manner, and due to long-term extrusion, the roller bearing is worn and a gap appears, resulting in the yaw of the static pressure ring. In the embodiment of this process method, a combination of a roller contact fixing manner and a static pressure water seal fixing manner is adopted to fix the static pressure ring. On the one hand, it is avoided that it is difficult to achieve a stable fixing effect only relying on the water pressure generated by the water inlet. On the other hand, even if a gap appears and yaw occurs due to the wear of the roller caused by long-term extrusion, the entire annular retainer 100 will automatically move downward under the action of gravity, relatively improving the stability during production. See specifically Figure 6 。

[0081] In the double-sided thinning process method, it further includes S500: a step of clamping the workpiece 13 to be processed. At the end stage of thinning, water is continuously sprayed from the water supply hole 21 on one side of the static pressure pad 200 / 300 to generate water pressure, so that the workpiece 13 to be processed is pushed onto the static pressure pad 200 / 300 on the other side, that is, the workpiece 13 is adsorbed on the static pressure pad 200 / 300 by the surface tension of water, and then clamped by the suction cup on the robotic arm. This method is called the surface tension adsorption method. See specifically Figure 5 。

[0082] In the prior art, since a vacuum adsorption point is arranged on the back of the static pressure pad, vacuum can be directly pumped to realize the vacuum adsorption of the workpiece to be processed. In the existing vacuum adsorption method, due to the strong acting force of the adsorption point, foreign matters on the static pressure pad cause defects on the surface of the workpiece near the vacuum point. The surface tension adsorption method adopted in this application can, to a certain extent, avoid the surface defects formed in the workpiece clamping step compared with the existing vacuum adsorption method.

[0083] See specifically Figure 5, a plurality of water supply ports 21 are respectively provided on the first static pressure pad 200 and the second static pressure pad 300. After the thinning stage of the workpiece 13 is completed, a water spraying device (not shown) continuously sprays water through the water supply ports 21 of one side of the static pressure pad 200 / 300, extends the water spraying time, generates water pressure, and under the action of this pressure, pushes the workpiece onto the other side of the static pressure pad 200 / 300, and then clamps it through the suction cup on the robotic arm. In addition, during the grinding process, water is continuously supplied through the water supply ports 21 of both sides of the static pressure pads 200 / 300, and the grinding chips generated during the operation of the workpiece 13 can be removed in a timely manner. Further, in order to eliminate the deviation caused by the water pressure, the water supply ports 21 can be symmetrically distributed on both sides of the static pressure pads 200 / 300, and the water pressure is kept consistent, so that the surface of the workpiece 13 is uniformly stressed, effectively avoiding the yaw caused by the water pressure and improving the production stability.

[0084] This double-sided thinning method S500: In the step of clamping the workpiece 13, it is found that the existing suction cup uses a suction cup made of hard plastic material. Since the part in direct contact with the workpiece is a hard material, long-term use will cause its surface to be rough, and foreign substances are likely to adhere to its surface, resulting in repetitive fixed-point defects when adsorbing the workpiece. In addition, in actual production, the position where the robotic arm clamps the workpiece needs to be set at a fixed position. If the suction cup is completely made of soft material such as rubber, normal clamping cannot be completed. For details, see Figure 8 .

[0085] To address the above problems, the present application provides a soft material 51 with a thickness of 1-3 microns on the surface part of the hard suction cup 500 in contact with the workpiece. In this way, when adsorbing the workpiece, it is ensured that only the soft material 51 is in contact with the workpiece on the part of the hard suction cup 500, buffering and reducing the pressure during contact, and reducing the defects on the surface of the workpiece caused by adsorption. Further, as Figure 9 shown, the present application uses the soft material 51 on the entire contact surface part of the hard suction cup 500 and the workpiece, completely avoiding direct contact between the hard material and the workpiece. During the process of adsorbing the workpiece, the defects caused by adsorption can be avoided, and the operation is convenient. It should be noted that the "soft material" in the present application is a conventional material in the prior art, and those skilled in the art can select it according to actual needs as long as the above effects can be achieved, and details will not be elaborated here.

[0086] When the double-sided thinning device and method of the present application are applied to the processing of a wafer with a diameter of 300 mm and the initial thickness D 0 is not greater than 900 mm, compared with grinding under the same hardware conditions of the double-sided thinning device, it is found that the double-sided thinning device has a lower jump and runs very smoothly, that is, the machine tool does not need to be adjusted during operation at all, and the production is relatively stable.

[0087] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0088] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A double-sided thinning device, comprising: a ring-shaped retainer, the ring-shaped retainer includes a carrier ring and a hydrostatic pressure ring, the carrier ring radially supports the outer peripheral side of the workpiece to be processed, and drives the workpiece to be processed to rotate axially in the vertical direction through the carrier ring, and the hydrostatic pressure ring is fixedly arranged on the outer peripheral side of the carrier ring along the radial direction, two hydrostatic pads, namely a first hydrostatic pad and a second hydrostatic pad, the two hydrostatic pads are symmetrically arranged on both sides of the ring-shaped retainer respectively, a feed shaft, the feed shaft is arranged at the lower opening of the hydrostatic pad and moves along the axial direction, and the grinding wheel on the feed shaft directly grinds the workpiece through the opening, It is characterized in that the yaw amount of the static pressure ring is 40 to 50 microns, the flatness of the surface of the static pressure pad is below 30 microns, and the distance between the first static pressure pad and the second static pressure pad is D 0 +130 to D 0 +150 microns, where D 0 is the initial thickness of the workpiece to be processed, with the unit of micron.

2. The device according to claim 1, wherein, The thickness of the static pressure ring is set to D 0 + (130~150) microns + 2X - (40~50) microns, where X is the reserved interval for the operation of the static pressure pad and the static pressure ring, and the unit is micron.

3. The device according to claim 1 or 2, wherein, a positioning groove driving piece is arranged on the carrier ring, the positioning groove driving piece is separated from the carrier ring, the workpiece to be processed is directly stuck on the positioning groove driving piece, and the rotation of the positioning groove driving piece drives the movement of the workpiece.

4. The device according to claim 3, wherein, The thickness of the positioning groove driving piece in the grinding area is D 1 -80 to D 1 -100 microns. The thickness of the positioning groove driving piece outside the grinding area is greater than the thickness in the grinding area, where D 1 is the final thickness of the machined workpiece, with the unit of micron.

5. The device according to claim 4, wherein, the positioning groove driving piece is in the same plane as the carrier ring, the workpiece to be processed is directly stuck on the carrier ring, and the movement of the driving point of the positioning groove driving piece on the carrier ring drives the rotation of the entire workpiece.

6. The device according to claim 1 or 2, wherein, two contact rollers and two hydrostatic guide wheels are arranged on the outer periphery of the hydrostatic pressure ring, and water pressure is applied through the water inlet of the hydrostatic guide wheel, and pressure is generated by water to pressurize and fix the hydrostatic pressure ring.

7. A method for double-sided thinning using the device according to any one of claims 1-6, wherein, comprising: (1) Grinding wheel approaching stage: Initially, the interval of the grinding wheel is set to the initial thickness of the workpiece; (2) Rough machining stage: The removal amount in the rough machining stage is determined by the cutting conditions; (3) Finishing machining stage: The removal amount in the finishing machining stage is determined according to the rough machining stage; (4) Trimming and thinning stage: The removal amount in the trimming and thinning stage is 0-5 microns; Among them, before step (1), the yaw amount of the static pressure ring is 40 to 50 microns, and the distance between the two static pressure pads is set to D 0 +130 to D 0 +150 microns, D 0 is the initial thickness of the workpiece to be machined, in microns 8. The method according to claim 7, wherein, Before the step (1), set the thickness of the static pressure ring to D 0 + (130 to 150) microns + 2X - (40 to 50) microns, where X is the gap reserved for the operation of the static pressure pad and the static pressure ring, and the unit is micron.

9. The method according to claim 8, wherein, A positioning groove driving piece is arranged on the bearing ring. The positioning groove driving piece is separated from the bearing ring. The workpiece to be processed is directly clamped on the positioning groove driving piece. The rotation of the positioning groove driving piece drives the workpiece to move. Before the step (1), the thickness of the positioning groove driving piece in the grinding area is set to be D 1 -80 to D 1 -100 microns. The thickness of the positioning groove driving piece outside the grinding area is greater than that in the grinding area, where D 1 is the final thickness of the workpiece to be processed, and the unit is micron.

10. The method according to claim 7, wherein, Before the step (1), two contact rollers are arranged at the bottom of the outer periphery of the hydrostatic pressure ring and two hydrostatic guide wheels are arranged at the upper part, water pressure is applied through the water inlet of the upper hydrostatic guide wheel to form a water film on the hydrostatic pressure ring, and pressure generated by the water film is used to pressurize and fix the hydrostatic pressure ring.

11. The method according to claim 7, wherein, it further includes (5): a step of clamping the workpiece, the water supply hole on one hydrostatic pad continuously sprays water, so that the workpiece is pushed towards the other hydrostatic pad under the action of water pressure, and the workpiece is adsorbed by the hard suction cup.

12. The method according to claim 11, wherein, in the step (5), a soft material with a thickness of 1-3 microns is provided on the surface of the hard suction cup in contact with the workpiece, or a soft material is arranged on the entire surface of the hard suction cup in contact with the workpiece.

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