Study into grinding force in back grinding of wafer with outer rim
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Study into grinding force in back grinding of wafer with outer rim Xiang-Long Zhu1 • Yu Li1 • Zhi-Gang Dong1 • Ren-Ke Kang1 • Shang Gao1
Received: 3 December 2019 / Revised: 29 January 2020 / Accepted: 13 June 2020 Ó Shanghai University and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Back grinding of wafer with outer rim (BGWOR) is a new method for carrier-less thinning of silicon wafers. At present, the effects of process parameters on the grinding force remain debatable. Therefore, a BGWOR normal grinding force model based on grain depth-of-cut was established, and the relationship between grinding parameters (wheel infeed rate, wheel rotational speed, and chuck rotational speed) and normal grinding force was discussed. Further, a series of experiments were performed to verify the BGWOR normal grinding force model. This study proves that the BGWOR normal grinding force is related to the rotational direction of the wheel and chuck, and the effect of grinding mark density on the BGWOR normal grinding force cannot be ignored. Moreover, this study provides methods for reducing the grinding force and optimizing the back thinning process of the silicon wafer. Keywords Silicon wafer Back grinding of wafer with outer rim (BGWOR) Grinding force Grinding mark density List of symbols dg-max The maximum grain depth-of-cut dl Length of grinding line dV Removal volume of material f Wheel infeed rate fr Ideal infeed depth per wheel revolution
fr0 k ns nw r tr z=0 zw rdr/dl As BGWOR E1 E2 F Fc Fs Ftotal L Ncut Rg SSD W a cv t1 t2
Actual infeed depth per wheel revolution Chip thickness coefficient Wheel rotational speed Chuck rotational speed Radial distance of wafer Time per wheel revolution End face of wheel Wafer surface Reciprocal of grinding marks density Equivalent cutting area of single abrasive grain Back grinding of wafer with outer rim Young’s modulus of wafer Young’s modulus of diamond Normal force for a single abrasive grain Normal cutting force Normal sliding force Total normal grinding force Circumference of grinding wheel Number of effective cutting grains Radius of abrasive grain Depth of subsurface damage Width of grinding wheel segment Overlap coefficient Grain volume ratio Poisson’s ratio of wafer Poisson’s ratio of diamond
1 Introduction & Ren-Ke Kang [email protected] 1
Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, People’s Republic of China
Silicon wafers are the most widely used substrate material in integrated circuit manufacturing [1–3]. Back grinding of wafer with outer rim (BGWOR) is a new method for carrier-less thinning of silicon wafers, and its working principle is shown in Fig. 1. Different from conventional back
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results and the theoretical model about the effect of chuck rotational speed on the grinding force in the Ref. [8]. In view of the above, it is necessary to study the grinding force in the back thinning process of silicon wafers fu
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