Crystal plasticity analysis of lattice defect generation in ULSI cells

Abstract

The periodic structure of the shallow trench isolation (STI) type ULSI cells is generally used for the latest semiconductor device structure. However, dislocations are accumulated when the device size becomes small, and in the electron channel they have an enormous effect on the electronic state and obstruct the device from normal operation. In this paper, we model the periodic structure of the STI type ULSI cells, and analyze plastic slip that takes place in the devices during the oxidation process of oxide film and evaluate the accumulation of dislocations that accompany plastic slip. For the analysis of slip deformation, we use a crystal plasticity analysis program which is based on the finite element technique. The result shows that stress concentrations at the shoulder part of the device area and bottom corner of trench cause plastic slip and dislocation accumulation, and directions of these dislocation lines are mostly parallel to z axis and this means that these dislocations are approximately 60°mixed type.