The investigation for introduction of SAC etching technique to mass productive DRAM process

A self aligned contact hole (SAC) etching technique has been investigated for a mass production DRAM process. A Dipole Ring Magnetron RIE (DRMRIE) system with CO additional C4F8 gas chemistry is applied to SAC etching because of its maturity with consideration of COO and COC. Hardware improvement and process optimization can widen the process window 9 times as large. Stopper Si₃N₄ removal process and device characteristics are evaluated to decide minimum limitation of SAC shoulder residue. In-line observation with SEM measurement is employed for administration of the SAC process. Stable process repeatability is realized and a successful SAC process for mass production is completed in this examination