Wafer thinning grinding wheel

Abstract

The utility model provides a kind of wafer thinning grinding wheel, it is related to wafer processing equipment technical field, comprising: base body, it is discoid;Multiple grinding teeth, the grinding tooth is prismatic column, each the grinding tooth is arranged along the edge of the base body interval a week, the long diagonal of each the grinding tooth is along the base body circumferential arrangement, short diagonal is along the base body radial arrangement, the long diagonal length of the grinding tooth is 2~6mm, short diagonal length is 1~4mm, the pitch of adjacent two the grinding tooth is 0.1~3mm.The utility model has the beneficial effect: when base body rotates, use the grinding face of the diamond shape of grinding tooth to promptly discharge silicon scrap in grinding process, grinding tooth grinding face area is smaller and closely layout, improve the efficiency of chip removal, improve wafer surface grinding quality;Avoid stress concentration in grinding tooth grinding face local area in grinding process, effectively reduce the generation of stress concentration;Wafer feeding speed can be improved, improve processing efficiency.

Description

Technical Field

[0001] This utility model relates to the field of wafer processing equipment technology, and in particular to a wafer thinning grinding wheel. Background Technology

[0002] Silicon wafer thinning is a core process in integrated circuit packaging and semiconductor substrate manufacturing, requiring high surface accuracy and low subsurface damage during planarization and ultra-thinning processes. Traditional grinding wheels suffer from problems such as low chip removal efficiency, stress concentration, and excessive machine load due to design flaws in their grinding tooth profiles. Specifically:

[0003] 1. Low chip removal efficiency leads to surface scratches and secondary damage.

[0004] Traditional grinding wheels use wide tooth profiles (such as rectangular or trapezoidal teeth, with a single tooth length > 10mm and width > 3mm on the grinding surface). During grinding, silicon chips are discharged through the gaps between the grinding teeth. The excessively large grinding area of ​​a single tooth prevents effective chip removal, resulting in chip accumulation. Furthermore, the wide tooth profile hinders the washing of chips by the grinding fluid, causing hard chips to remain in the processing area, scratching the silicon wafer surface and forming microcracks.

[0005] 2. Excessive contact area per tooth leads to stress concentration during grinding.

[0006] Traditional grinding wheels have a large single-tooth contact area (e.g., rectangular tooth area > 40 mm²), and the grinding force is concentrated in a local area. When this exceeds the critical stress threshold for grinding the ductile domain of silicon wafers (corresponding to a grinding depth < 0.06 μm), it will lead to increased subsurface damage. Stress concentration will cause microcrack propagation, with crack depth > 2 μm, reducing the mechanical properties of silicon wafers and thus leading to a decrease in yield. In subsequent cutting or packaging, the propagation of hidden cracks will result in a fragmentation rate > 5%, requiring high-cost chemical mechanical polishing (CMP) for repair.

[0007] 3. Excessive grinding resistance increases machine load and energy consumption.

[0008] Large-tooth grinding wheels have low chip removal efficiency per tooth, resulting in high equipment power requirements: the spindle motor has a large power, increasing energy consumption; in order to avoid overload, the feed speed is forced to be reduced, the process parameters are limited, and the processing efficiency decreases. Utility Model Content

[0009] In view of this, in order to solve the problems of low chip removal efficiency, grinding force concentration in local areas of grinding teeth, and excessive grinding resistance in the traditional grinding wheel wafer grinding process, a new method is needed.

[0010] An embodiment of this utility model provides a wafer thinning grinding wheel.

[0011] An embodiment of this utility model provides a wafer thinning grinding wheel, comprising:

[0012] The matrix is ​​disc-shaped;

[0013] Multiple grinding teeth, each grinding tooth being a prismatic column, are arranged at intervals around the edge of the substrate. The long diagonal of each grinding tooth is arranged circumferentially along the substrate, and the short diagonal is arranged radially along the substrate. The length of the long diagonal of each grinding tooth is 2-6 mm, the length of the short diagonal is 1-4 mm, and the distance between two adjacent grinding teeth is 0.1-3 mm.

[0014] Furthermore, the distance between two adjacent grinding teeth is 1~3mm.

[0015] Furthermore, the distance between two adjacent grinding teeth is 0.1~1mm.

[0016] Furthermore, the height of the grinding teeth is 5~9mm.

[0017] Furthermore, the edge of the substrate is provided with a raised annular boss, the inner side of the annular boss is an inclined surface, the top of the annular boss is provided with an annular mounting groove, and each of the grinding teeth is evenly spaced and fixed in the mounting groove.

[0018] Furthermore, the mounting groove is provided with uniformly distributed tooth grooves in the circumferential direction, and each grinding tooth is bonded to a tooth groove.

[0019] Furthermore, the substrate is made of aluminum alloy, with an outer diameter of 160mm and a thickness of 20mm.

[0020] Furthermore, the grinding teeth are made of a mixture of abrasive diamond / silicon carbide, ceramic binder and pore-forming agent.

[0021] Furthermore, the flatness error of the grinding end face of the grinding tooth is ≤0.01mm.

[0022] Furthermore, the substrate is provided with multiple mounting holes.

[0023] The beneficial effects of the technical solution provided by the embodiments of this utility model are as follows:

[0024] 1. The present invention relates to a wafer thinning grinding wheel, which uses prismatic grinding teeth. The long diagonal of the grinding teeth is arranged along the circumference of the substrate, and the short diagonal is arranged along the radial direction of the substrate. When the substrate rotates, the diamond-shaped grinding surface of the grinding teeth is used to promptly remove silicon chips during the grinding process. The grinding surface area of ​​the grinding teeth is small and closely arranged, which improves chip removal efficiency and improves the grinding quality of the wafer surface.

[0025] 2. The wafer thinning grinding wheel of this utility model has a smaller grinding surface area of ​​the grinding teeth and a smaller contact area between a single grinding tooth and the wafer, which avoids stress concentration in local areas of the grinding surface of the grinding teeth during the grinding process, effectively reducing the generation of stress concentration, reducing the machine load by 20%, and reducing the wafer warpage caused by stress by 20%.

[0026] 3. The wafer thinning grinding wheel of this utility model can improve the wafer feed speed and processing efficiency because the grinding debris can be discharged in time. It can also be adapted to grinding 100~300mm silicon wafers, reducing the thickness to 20~100μm, thus expanding the scope of application. Attached Figure Description

[0027] Figure 1 This is a perspective view of a wafer thinning grinding wheel according to the present invention;

[0028] Figure 2 This is a front view of a wafer thinning grinding wheel according to this utility model;

[0029] Figure 3 yes Figure 2 A magnified view of a section at point A in the middle;

[0030] Figure 4 This is a schematic diagram of a ground tooth;

[0031] Figure 5 This is a schematic diagram of an existing grinding wheel.

[0032] In the diagram: 1. Base; 2. Grinding teeth; 3. Mounting hole; 4. Annular boss; 5. Mounting groove; 6. Long diagonal; 7. Short diagonal. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this utility model clearer, the embodiments of this utility model will be further described below with reference to the accompanying drawings. The following description presents a preferred embodiment of several possible embodiments of this utility model, intended to provide a basic understanding of the utility model, but not intended to identify the key or decisive elements of the utility model or to limit the scope of protection sought.

[0034] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0035] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures. Also, it should be understood that, for ease of description, the dimensions of the various parts shown in the figures are not drawn to actual scale.

[0037] Please refer to Figure 1 and 2 An embodiment of this utility model provides a wafer thinning grinding wheel, including a substrate 1 and a plurality of grinding teeth 2.

[0038] The base 1 is disc-shaped and is used to mount and fix each of the grinding teeth 2. The base 1 is generally made of aluminum alloy, such as 6061-T6 high-strength aluminum alloy used in this embodiment, and is machined by CNC lathe.

[0039] It should be noted that the dimensions of the substrate 1 can be flexibly set according to the actual needs of wafer grinding. For example, in this embodiment, the outer diameter of the substrate 1 is 160 mm and the thickness is 20 mm.

[0040] The base 1 is generally provided with multiple mounting holes 3, through which it is mounted on the spindle, and thus rotates under the drive of the spindle.

[0041] Combination Figure 3 and 4 As shown, the grinding teeth 2 are prismatic prisms, and each grinding tooth 2 is arranged at intervals around the edge of the base 1. The long diagonal 6 of each grinding tooth 2 is arranged circumferentially along the base 1, and the short diagonal 7 is arranged radially along the base 1. The length of the long diagonal 6 of the grinding tooth 2 is 2~6mm, the length of the short diagonal 7 is 1~4mm, and the distance between two adjacent grinding teeth 2 is 0.1~3mm.

[0042] The number of grinding teeth 2 is flexibly set according to the outer diameter of the base 1 and the shape and size of each grinding tooth 2. Generally, the grinding teeth 2 are evenly spaced along the edge of the base 1 and arranged in a circle.

[0043] The grinding teeth 2 are made of a mixture of abrasive diamond / silicon carbide, ceramic binder, and pore-forming agent. The specific manufacturing process is as follows:

[0044] Abrasive formulation: Mix the following components by mass ratio: 45 parts diamond, size 3-5µm; 40 parts ceramic binder (N2O-Al2O3-SiO2-B2O3 system), passed through a 400-mesh sieve; 15 parts pore-forming agent (PS microspheres), microsphere diameter 50-80µm; ball mill the above components for 4-6 hours until homogeneous;

[0045] Press molding: The mixture is filled into a special mold and pressed into a rhomboid tooth blank using an isostatic pressing process (pressure 100~200MPa). The dimensions are precisely controlled as follows: the length of the long diagonal 6 is 2~6mm, the length of the short diagonal 7 is 1~4mm, and the tooth height is 5~9mm (including sintering shrinkage compensation).

[0046] Sintering and curing: Under a nitrogen protective atmosphere, the temperature is increased to 450℃ at 5℃ / min and held for 1 hour; then increased to 650℃ at 3℃ / min and held for 2 hours; and then decreased to 450℃ at 5℃ / min. The temperature is then cooled to room temperature with the furnace. The cutting teeth form rhomboid grinding teeth 2 with a microporous structure (porosity 65%), and the bending strength of a single tooth is ≥10MPa.

[0047] The base 1 has a raised annular boss 4 on its edge. The inner surface of the annular boss 4 is inclined. The top of the annular boss is provided with an annular mounting groove 5. Each of the grinding teeth 2 is evenly spaced and fixed in the mounting groove 5. The mounting groove 5 has evenly distributed tooth grooves around its circumference, and each of the grinding teeth 2 is bonded to one tooth groove.

[0048] Specifically, the tooth grooves are pre-fabricated during the machining of the substrate 1: uniformly distributed tooth grooves are precision milled into the substrate 1, and the cross-sectional shape of the tooth grooves is the same as that of the grinding tooth 2, which is also rhomboid. The groove depth is 1~2mm, and the bottom roughness Ra≤1.6μm to ensure the bonding strength of the grinding tooth 2. High-temperature resistant epoxy resin adhesive (shear strength ≥20MPa) is used to embed the sintered grinding tooth 2 into the tooth grooves, with a positioning accuracy ≤0.02mm. Curing treatment: heating and curing at 80℃ for 2 hours forms a rigid connection interface, ensuring that there is no risk of the grinding tooth 2 falling off during the grinding process.

[0049] In some embodiments, a wafer thinning grinding wheel of the present invention is applied to rough grinding of wafers, and the spacing between two adjacent grinding teeth 2 is set to 1~3mm.

[0050] In some embodiments, a wafer thinning grinding wheel of the present invention is applied to wafer fine grinding, and the spacing between two adjacent grinding teeth 2 is set to 0.1~1mm.

[0051] In some embodiments, in order to ensure that the runout of the grinding wheel end face is within the required range, a diamond grinding wheel is used to perform precision grinding on the grinding end face of the grinding tooth 2, so that its flatness error is ≤0.01mm, thereby ensuring that the runout of the grinding wheel end face is <0.01mm.

[0052] After dynamic balancing correction, the grinding performance of the wafer thinning grinding wheel in this embodiment was tested.

[0053] Grinding wheel dynamic balancing correction

[0054] Dynamic balancing test: The imbalance of the grinding wheel is tested on a special balancing machine at a speed of 1000~2000 r / min, and the mass deviation area is marked.

[0055] Imbalance torque adjustment: The substrate 1 is processed by a precision engraving removal device to make the residual imbalance ≤1.2g·mm, which meets the stability requirements of high-speed grinding.

[0056] Grinding performance test

[0057] The DXSG320 instrument was used to test grinding wheel samples. The wafer size was 12 inches. The test results were as follows: Figure 5 Compare with the existing grinding wheels shown.

[0058] The test results of the wafer thinning grinding wheel in this embodiment and the existing grinding wheel are shown in the table below:

[0059]

[0060] The comparison shows that the wafer surface roughness RA value of the wafer thinning grinding wheel in this embodiment is reduced by 15%; TTV is reduced by 20%; the machine load is reduced by 15%; the wafer warpage caused by stress is reduced by 10%; and the feed rate is increased to 40~100µm / min.

[0061] In this document, the directional terms such as front, back, top, and bottom are defined based on the position of the components in the accompanying drawings and their relative positions to each other, solely for the purpose of clarity and convenience in expressing the technical solution. It should be understood that these are relative concepts and can vary depending on different methods of use and placement; the use of these directional terms should not limit the scope of protection claimed in this application.

[0062] Where there is no conflict, the embodiments and features described above can be combined with each other. The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A wafer thinning grinding wheel, characterized in that, include: The matrix is ​​disc-shaped; Multiple grinding teeth, each grinding tooth being a prismatic column, are arranged at intervals around the edge of the substrate. The long diagonal of each grinding tooth is arranged circumferentially along the substrate, and the short diagonal is arranged radially along the substrate. The length of the long diagonal of each grinding tooth is 2-6 mm, the length of the short diagonal is 1-4 mm, and the distance between two adjacent grinding teeth is 0.1-3 mm.

2. The wafer thinning grinding wheel as described in claim 1, characterized in that: The distance between two adjacent grinding teeth is 1~3mm.

3. The wafer thinning grinding wheel as described in claim 1, characterized in that: The distance between two adjacent grinding teeth is 0.1~1mm.

4. The wafer thinning grinding wheel as described in claim 1, characterized in that: The height of the grinding teeth is 5~9mm.

5. The wafer thinning grinding wheel as described in claim 1, characterized in that: The edge of the substrate is provided with a raised annular boss, the inner side of the annular boss is an inclined surface, and the top of the annular boss is provided with an annular mounting groove, and each of the grinding teeth is fixed in the mounting groove at even intervals.

6. The wafer thinning grinding wheel as described in claim 5, characterized in that: The mounting groove is provided with uniformly distributed tooth grooves in the circumferential direction, and each grinding tooth is bonded to a tooth groove.

7. The wafer thinning grinding wheel as described in claim 1, characterized in that: The substrate is made of aluminum alloy, with an outer diameter of 160mm and a thickness of 20mm.

8. A wafer thinning grinding wheel as described in claim 1, characterized in that: The grinding teeth are made of a mixture of abrasive diamond / silicon carbide, ceramic binder and pore-forming agent.

9. A wafer thinning grinding wheel as described in claim 1, characterized in that: The flatness error of the grinding end face of the grinding teeth is ≤0.01mm.

10. A wafer thinning grinding wheel as described in claim 1, characterized in that: The substrate has multiple mounting holes.

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