Papers by Keyword: Silicon Wafer

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Authors: Hong Tsu Young, Hung Yi Huang, Ying Jay Yang
Abstract: The advantages of ductile regime grinding of silicon wafer such as smooth surface roughness (Ra < 10 nm) and minimum subsurface damage layer (< 10μm) have great impact on the production process of wafer. With ductile regime grinding, the subsequent processes such as etching and rough polishing processes can be minimized. To achieve ductile regime grinding, a fundamental concept is the application of grain depth of cut being less than the critical cut depth, dc, of the silicon wafer. However, dc is dependent on material properties, cutting conditions, and crystallographic orientation [1].The objective of this paper is to derive, and to investigate by experiment, the dc value for silicon wafer grinding. Following these key steps, the effects of dc on various major grinding parameters are studied.
Authors: Feng Wei Huo, Zhu Ji Jin, Ren Ke Kang, Dong Ming Guo
Abstract: A new non-destructive method was developed to identify the grinding mode of silicon wafers, which is based on the information of subsurface cracks extracted from the surface topography of the ground silicon wafers measured with a 3D surface profiler. We examined extensive measurement data of the surface topography of silicon wafers processed by single grain grinding or real grinding operation, and our results show that the information about median cracks could be captured if the lateral sampling interval of the 3D surface profiler is small enough, even if the grain depth of cut is below 20nm. If the maximum valley of the measured surface topography is approximately equal to the grain depth of cut, surface formation will be under ductile mode, whereas, if the maximum valley is several times larger than the grain depth of cut, surface formation will be under brittle mode. According to this criterion, silicon wafers ground by ductile mode or brittle mode could be identified rapidly and conveniently. Experimental validation shows that this method is accurate.
Authors: Wen Jia Zuo, Xiao Hui Du, Hao Er Zhang, Yuan Zhe Su, Ting Ping Lei, Ling Yun Wang, Dao Heng Sun
Abstract: In this paper, a novel lapping method based on regulating the position of carrier centroid is proposed to modify interfacial normal pressure uniformity. Eight special points are selected to represent carrier weight. This lapping process can be divided into initial stage, regulated stage and stable stage. The purpose of initial stage is calculating the position of carrier centroid according to the equivalent mass of eight points. The regulated stage is to decrease total thickness variation (TTV) by regulating the position of weight. Finally, the stable stage will keep uniformity of material removal rate (MRR) uniform at each point. A 3-inch and 400 μm thickness silicon wafer is lapped to demonstrate the feasibility of this method. We can find that TTV of this wafer decreases from initial stage 20 μm to 3 μm and remain constant. Therefore, the uniformity of MRR has been greatly improved by this novel lapping method.
Authors: Jun Zhang, Bo Liu, Min Qian, Xiang Long Zhu, Ren Ke Kang
Abstract: A Novel Piezoelectric Grinding Dynamometer for Monitoring Ultra-precision Grinding of Silicon Wafers
Authors: Y.B. Tian, Li Bo Zhou, Jun Shimizu, H. Sato, Ren Ke Kang
Abstract: The demand for extremely-thin Si wafers is expanding. Current manufacturing technologies are meeting great challenges with the continuous decrease in Si wafer thickness. In this study, a novel single step thinning process for extremely thin Si wafers was put forward by use of an integrated cup grinding wheel (ICGW) in which diamond segments and chemo-mechanical grinding (CMG) segments are alternately allocated along the wheel periphery. The basic machining principle and key technologies were introduced in detail. Grinding experiments were performed on 8-in. Si wafers with a developed ICGW to explore the minimal wafer thickness and grinding performance. The experimental results indicate that the proposed grinding process with the ICGW is an available thinning approach for extremely thin Si wafer down to 15μm
Authors: Wei Li, Xiao Dong Hu, Yang Fu Jin, Gang Xiang Hu, Xiao Zhen Hu
Abstract: Double sided polishing process has become a main machining method for silicon wafer finishing process, but it is difficult to get ultra-smooth surface with the very stringent machining conditions. In this paper, the mechanism of ultra-smooth surface machining process was studied, the main parameters affecting the surface quality of silicon wafer, such as the polishing pad and carrier rotation speed, polishing press, polishing slurries etc. , were discussed and optimized, then ultra-smooth surface of silicon wafer with Ra 0.4nm has been obtained based on the above study. A new double sided polishing machine with computer control system equipped with a digital controlled press valve was developed, and the ultra-smooth machining process of silicon wafer was established in this paper.
Authors: Chun Hui Chung
Abstract: Fixed diamond wire saw has the advantages such as higher cutting rate and clearer operating environment over the slurry wire saw in wafering. However, the higher cost and poor sliced wafer surface are still the obstacles for the diamond wire saw to totally replace slurry wire saw. In this study, the distribution of diamond grits on the wire was investigated by numerical simulation. The results show that there is a critical value of the abrasive interval to transfer the machining mechanism from plastic plowing to brittle indentation cracking for the material removal. The value depends on both the wire tension and bow angle during the operation.
Authors: Takahiro Miyake, Toshiyuki Enomoto
Abstract: In recent years, the achievement of further high flatness of workpiece edge shape is strongly required in mirror finishing. Especially, the edge roll off of silicon wafers as the substrates of semiconductor devices is demanded to decrease in the polishing process for raising the yield of IC chips. Many theoretical and experimental analyses for the edge roll off generation have been already done to meet the demand. The analyses, however, cannot fully account for the obtained edge shape in actual polishing. Concretely, the influence of the polishing pressure as one of the key polishing conditions on the edge roll off has not been clarified. In this study, the influence of the polishing pressure on the edge shape was investigated by the polishing experiments and the edge roll off generation analyses using the model based on the viscoelasticity of the polishing pad, which was proposed in the previous study. And it was revealed that an appropriate polishing pressure is needed to be set for achieving high flatness of workpiece edge shape with the consideration of the properties of applied polishing pads.
Authors: Y.S. Lv, Nan Li, Jun Wang, Tian Zhang, Min Duan, Xue Ling Xing
Abstract: In order to make the contact pressure distribution of polishing wafer surface more uniform during chemical mechanical polishing (CMP), a kind of the bionic polishing pad with sunflower seed pattern has been designed based on phyllotaxis theory, and the contact model and boundary condition of CMP have been established. Using finite element analysis, the contact pressure distributions between the polishing pad and wafer have been obtained when polishing silicon wafer and the effects of the phyllotactic parameter of polishing pad on the contact pressure distribution are found. The results show that the uniformity of the contact pressure distribution can be improved and the singularity of the contact pressure in the boundary edge of polished wafer can be decreased when the reasonable phyllotactic parameters are selected.
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