Development of sub 10-µm ultra-thinning technology using device wafers for 3D manufacturing of terabit memory

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 m I
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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.