Patent ID: 8247297

Claim:
A method of creating a semiconductor device structure with an oxide-filled large deep trench (OFLDT) portion having trench size TCS and trench depth TCD, the method comprises: a) providing a bulk semiconductor layer (BSL), having a thickness BSLT>TCD, and mapping out a large trench top area (LTTA) atop the BSL with its geometry equal to that of OFLDT; b) partitioning the LTTA into interspersed, complementary interim areas ITA-A and ITA-B each of pre-determined geometry; c) creating into the top BSL surface, a plurality of interim vertical trenches so as to remove bulk semiconductor materials corresponding to ITA-B till the depth TCD; and d) selectively forming an interim oxidation prevention layer upon the deep active device trenches; and e) selectively converting the remaining bulk semiconductor materials corresponding to ITA-A into oxide and, should there be any residual space left between the so-converted ITA-A, filling up the residual space with oxide; f) removing the interim oxidation prevention layer and forming a liner oxide upon the deep active device trenches.