ISOLATION METHOD FOR SEMICONDUCTOR DEVICE OF SILICON-ON-INSULATOR TYPE

摘要

PURPOSE: An isolation method for a semiconductor device of a silicon-on-insulator(SOI) type is provided to attain good gate oxide characteristics and good transistor characteristics. CONSTITUTION: In the method, an SOI substrate has a buried oxide layer(101) and a surface silicon layer(102) formed on a silicon substrate(100). The first insulating layer(103) and the second insulating layer are then formed on the SOI substrate and etched to form an opening therein. Next, the surface silicon layer(102) is etched through the opening in the insulating layers(103) to form a trench therein. Thereafter, nitrogen ions are implanted into the etched silicon layer(102) and the exposed oxide layer(101) to form a nitrogen-implanted silicon layer(152). Then, a thermal oxide layer(160) is formed on a sidewall of the surface silicon layer(102). Next, the third insulating layer is formed enough to fill the trench in the surface silicon layer(102) and then polished or etched. Therefore, the third insulating layer is removed together with the second insulating layer, but remains in the trench(180).