Development of ultra-thinning technology for logic and memory heterogeneous stack applications

200 mm and 300 mm device wafers were successfully thinned down to less than 10 μm. A 200 nm non-crystalline layer remaining after the high-rate Back Grind process was partially removed down to 50 nm by Ultra Poligrind process, or was completely removed with either Chemical Mechanical Planarization or Dry Polish. For FRAM device wafers thinned down to 9 μm, switching charge showed no change by the thinning process. CMOS logic device wafers thinned to 7 μm indicated neither change in I_on current nor junction leakage current. Thinning such wafers to <;10 μm will allow for lower aspect ratio less than 4 of Through Silicon-Via (TSV) in a via-last process.