Novel corner rounding process for Shallow Trench Isolation utilizing MSTS (Micro-Structure Transformation of Silicon)

A new STI (Shallow Trench Isolation) earner rounding technique with MSTS (Micro-Structure Transformation of Silicon) which utilizes Si-migration phenomenon with hydrogen ambient annealing [1] is proposed and applied to 0.15 mu m CMOS technology. Highly controlled corner rounding radius is achieved without high temperature oxidation process. Thus it is free from defect generation and undesirable impurity diffusion in Si substrate. Subthreshold current due to parasitic corner transistors of the STI structure is effectively suppressed and the reverse narrow channel effect is controlled down to 0.2 pm channel width.