A robust wafer thinning down to 2.6-μm for bumpless interconnects and DRAM WOW applications

An ultra-thinning down to 2.6-μm with and without Cu contamination at 10 ¹³ atoms/cm ² using 300-mm wafer proven by 2Gb DRAM has been developed for the first time. The impact of Si thickness and Cu contamination at wafer backside for DRAM yield including retention characteristics is described. Thickness uniformity for all wafers after thinning was below 2-μm within 300-mm wafer. A degradation in terms of retention characteristics occurred after thinning down to 2.6-μm while no degradation after thinning down to 5.6-μm for both wafer and package level test were found.