Modeling of stress-dependent wet etch characteristic for P-SOG STI process

Abstract

Recently, spin-on-glass (SOG) oxide has been used as an important technology to overcome the gap-filling limit of conventional high density plasma (HDP) oxide in shallow trench isolation (STI) process. One of them, a novel polysilazane spin-on-glass (P-SOG) film shows a complex mechanical behavior during an annealing process and an abnormal etch loading effect in the wet process. These unique properties of P-SOG film give many opportunities to stress engineering. This paper proposed the simulation methodology to predict mechanical stresses in STI process by modeling the volumetric shrinkage phenomena of P-SOG and wet etch rate which is dependent on hydrostatic pressure. By interfacing a commercial FEM code, ABAQUS and in-house topography simulator, each of which has a portion of necessary models regarding P-SOG, we can predict the mechanical stress distribution on the various STI structures with real process profiles.