High-Temperature Adhesives for Temporary Wafer Bonding Using a Sliding Approach

摘要

Wafer thinning has been used to dissipate heat and aid in facilitating IC miniaturization. A reduction in wafer thickness combined with an increasing wafer diameter produces the tendency for the wafer to warp and fold. Thinned wafers need to be supported during the backside grinding process and through the subsequent processes. Using temporary adhesives to attach the processed device wafer to a rigid carrier wafer offers an efficient solution. Currently available adhesives meet only a subset of performance requirements. None of them meet the requirement of high-temperature stability combined with ease of removal. In a previous paper we have reported our success in the development of high-temperature temporary adhesives to be used in wafer thinning applications at up to 250 ºC. This paper reports our progress on the new adhesives that can be used up to 350 ºC. The materials are soluble in industry-accepted safe solvents and can be spin-applied to required thicknesses and uniformity. The coated wafers can be bonded at 240-280ºC and debonded at 370-380ºC by using the sliding approach. The coatings can be removed easily without leaving any residue after debonding. The relationship of material properties,such as melt viscosity,viscoelasticity,thermal stability,and glass transition,with the application requirement is discussed.