Temporary bonding for High-topography Applications: Spin-on Material Versus Dry Film

Handling wafers with sub-100 μm thicknesses requires a support or carrier wafer during handling, transport and processing in a semiconductor process line. This thin wafer support system should be very stable during these operations but should also allow for easy wafer debonding. Therefore, room temperature debonding methods are the favored solutions, in particular, room temperature peel debonding, which is one the industry focuses on today. We have estimated that a TTV of less than 2μm is required to enable a `soft´ backside via reveal process for temporary bonding material thicknesses less than 20μm. For high frontside topography applications involving Cu pillars or C4 types of bumps, the challenge is to maintain a low post-grinding TTV value while processing the device wafer with thick temporary bonding materials (typically thicker than 50μm). Reducing the post-thinning TTV can be done either by reducing the edge bead effect of the spin-on temporary bonding material, or by looking into novel types of material applications such as thick film lamination. In this paper, we compare the thinning performance in terms of post-grinding TTV of two materials from Brewer Science: the thick spin-on ZoneBOND^®5150 material and the experimental BrewerBOND^TM dry film.