Copper chemical mechanical polishing and wafer thinning with temporary bonding for Through Silicon Via interconnect

Abstract

Copper chemical mechanical polishing (CMP) and wafer thinning technologies have been challenges for Through Silicon Via (TSV) interconnect in recent years. In this work, copper CMP slurry and process and wafer level thinning with temporary bonding were studied in detail. The concentration of peroxide (H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ), citric acid, SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> particle and Benzotriazole (BTA) in the CMP slurry and their effects were investigated. Key processes such as plate rotate speed, spin rotate speed, slurry dipping rate and load were also studied. Copper CMP slurry composition and process parameter were optimized to get good uniformity for different diameter TSVs. For wafer thinning, bonding and de-bonding processes for temporary bonding with Wafer Bond HT10.10 were optimized. Wafer thinning with temporary bonding glass was performed to obtain wafer thickness of 70μm and 50μm, respectively. Temporary bonding processes were carried out to satisfy the demand of different wire thickness in upside process. The thinned wafers (70μm, 50μm) were checked with Scanning Electron Microscopy (SEM) and thickness uniformity was good.