It was recalled that the periodic structure of shallow-trench isolation-type ULSI cells was useful for the latest semiconductor devices. However, dislocations sometimes accumulated in the electron channel when the devices were small, had a huge effect upon the electronic state and obstructed normal operation. The periodic structure of such cells was numerically modeled here, and the plastic slip that took place during the oxidation process was analyzed. The slip deformation was analyzed by means of a crystal plasticity analysis, which was based upon a finite element technique and the accumulation of dislocations which accompanied plastic slip was evaluated. The results revealed stress

concentrations at the shoulder part of the device area and the bottom corners of the trench for device isolation. The high stresses in these areas caused plastic slip and dislocation accumulation. The directions of these dislocation lines were mainly parallel to the trench direction. The dislocations were of approximately 60° mixed type.

Simulation of Dislocation Accumulation in ULSI Cells with STI Structure. T.Ohashi, M.Sato, T.Maruizumi, I.Kitagawa: Applied Surface Science, 2003, 216[1-4], 340-6