An analysis of the effect of the steps for isolation formation on STI process integration

In this paper we investigate the process parameters that influence the anomalous conduction through active oxide in STI isolation peripheral regions. First we report a detailed morphological analysis comparing the STI profile of a non-optimized and an optimized process for isolation formation, focusing our attention on STI divot shape and active oxide thinning. The optimization of STI formation process is then discussed evaluating the electrical impact of some process parameters on both area and edge intensive capacitors and analyzing the results of process simulations. The most important role in defining oxide quality results to be played by dummy oxide formation; also the wet etch used to remove the residual oxide before active dielectric growth stands out as directly related to poly wraparound and hump effect.