Study of Influence of STI Profile on Harp Gap-Filling Performance

HARP gap-filling performance is related with trench profile. In this paper, the influence of STI morphology on HARP gap-filling performance is studied. Both the slight undercut between top SiN and active area (AA), and top SiN CD, don't show impact on HARP gap-filling performance for the observed range. The side wall angle is key factor. For side wall angle of 89°, we have proved from both theory and experiment, that even 0.5° reduction of side wall angle can greatly reduce the STI void density.