Quarter-micron selective-epitaxial-silicon refilled trench (SRT) isolation technology with substrate shield

In order to realize high-density and stress-free field isolation for future ULSIs, the authors propose a selective-epitaxial-silicon refilled trench (SRT) isolation. The SRT isolation structure consists of a thin insulator film on the trench sidewalls, a selective-epitaxial-growth (SEG) silicon layer refilling the trench, and a capping oxide covering the trench openings. By using this isolation, the number of isolation process steps can be reduced to 60% of the number for a conventional process, and the stress induced by the thermal process can be minimal. The authors have succeeded in fabricating a 0.2- mu m isolation structure and have confirmed its excellent characteristics.<>