Sang-Ho Rha

A novel NF/sub 3/-HDP-CVD process for STI-filling in sub-90 nm DRAM and beyond

A complete filling of the shallow trench isolations (STI) in sub-90 nm DRAM is realized with the novel NF/sub 3/-HDP-CVD process. The gap-fill capability of the NF/sub 3/-HDP-CVD increased dramatically as NF/sub 3/ gas is added to the conventional SiH/sub 4//O/sub 2/ chemistry of HDP-CVD process. The effect of the NF/sub 3/-HDP-CVD processed STI is investigated by analyzing the transistor characteristics and yield in 512 M DRAM.

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

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