Structure Impaired Mechanical Stability of Ultra-thin Chips
Flexibility of ultra-thin chips is an important condition for applications in flexible electronics. Especially, mechanical reliability of ultra-thin chips is a key factor generally determining the final performance and reliability of a flexible electronics product. Structures and designs implemented on the chips are the elements that weaken the mechanical stability of the final product. In this chapter the excellent mechanical strength of 20-μm thin silicon chips produced by the ChipfilmTM technology is discussed. The influences of different parameters, such as the number of anchors per chip edge, the backside porous silicon and the topography formed by CMOS integration, on their mechanical reliability are investigated by means of uniaxial bending tests. The experimental results are statistically evaluated by the Weibull theory, in which the resulting failure stress data are used to obtain the fracture strength and estimate failure origins of the tested ultra-thin chips.
The authors would like to thank Astrid Kiss for her contributions to this work and also Lutz Diesing and Peter Ostrowski for their assistance in carrying out the mechanical experiments. The authors also thank the Landesstiftung Baden-Württemberg for the financial support (project ChipfilmTM).
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