Trench refill with selective polycrystalline materials

摘要

A trench refill for a semiconductor device is undertaken by depositing polycrystalline Ge or GexSi1-x alloy at temperatures as low as 500 DEG C. The structure is then oxidized at for example 700 DEG C. to obtain a cap oxide on the trench refill. This method causes avoidance of (1) void formation, (2) facet formation, and (3) necessity of a second insulator deposition and planarization, meanwhile achieving all these advantages at a low thermal budget.