Process optimization and simplification of self-aligned triple patterning

Abstract

Graphical abstractDisplay Omitted Highlights? A wet trimming process was developed to shrink mandrel line CD in SATP technique. ? The wet process smoothes out high-frequency components of LER. ? A selective dry etch is used to release the sacrificial spacers. ? CDU and LWR performance have been significantly improved. ? The first full-wafer 18nm L/S CDU and LWR data were reported. Self-aligned triple patterning (SATP) technology offers both improved resolution and design flexibility for scaling integrated circuits down to sub-15nm half pitch. By keeping and designing mandrel patterns which further define the route of the following spacers, SATP process represents a prospective trend that not only drives up the feature density, but also relaxes the overlay requirement with fewer masks and allows quasi-2D design flexibility. In this paper, we shall present the latest research progress made in optimization of existing SATP process to improve its lithographic performance such as CDU and line width roughness. In addition to solving the previously reported problems of etching small mandrels and sacrificial spacers, we also address the issue of reducing SATP process complexity/cost.