Title: Fabrication and evaluation for extremely thin Si wafer

Authors: Libo Zhou, Bahman Soltani Hosseini, Tatsuya Tsuruga, Jun Shimizu, Hiroshi Eda, Sumio Kamiya, Hisao Iwase, Yoshiaki Tashiro

Addresses: Department of Intelligent Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi 316-8511, Japan. ' Department of Intelligent Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi 316-8511, Japan. ' Department of Intelligent Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi 316-8511, Japan. ' Department of Intelligent Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi 316-8511, Japan. ' Department of Intelligent Systems Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi 316-8511, Japan. ' Material Engineering Div.II, Toyota Motor Co., 1 Toyota-cho, Toyota, Aichi 471-8572, Japan. ' Material Engineering Div.II, Toyota Motor Co., 1 Toyota-cho, Toyota, Aichi 471-8572, Japan. ' Tokyo Diamond Tool Mfg. Co., 2-3-5 Nakane, Meguro, Tokyo 152-0031, Japan

Abstract: Grinding process on the Si wafer develops subsurface damage, which remarkably degrades deflective strength of the wafer and constitutes a barrier against producing a thin wafer for low-profile packaging. In this paper, the authors propose a new index for evaluation of the Degree of Subsurface Damage (DSD). Requiring no costly instrument, the new index is easily calculated via the external geometry of the ground wafer. With the new index, it is able to quantitatively evaluate the subsurface damage introduced by different processes (or wheel) and to estimate the minimally achievable thickness of the wafer by each process. Also, a novel fixed abrasive process of Chemo-Mechanical Grinding (CMG) has been proposed for stress relief. All results indicate that the subsurface damage after CMG is nearly zero.

Keywords: thin silicon wafers; subsurface damage index; residual stress; damaged layer depth; fixed abrasive process; abrasive technology; chemo-mechanical grinding; CMG.

DOI: 10.1504/IJAT.2007.013852

International Journal of Abrasive Technology, 2007 Vol.1 No.1, pp.94 - 105

Published online: 30 May 2007 *

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