Total fidelity management in self-aligned multiple patterning process

Abstract

Through the continuous scaling with extension of 193-immersion lithography, the multi-patterning process with the grid-based design has become nominal process for fine fabrication to relax tight pitch designs^[1]. In self-aligned type multiple patterning, 7 nm node gate pattern was reported^[2],[3] and it was become a focal point LER on core-pattern is essential category to control pattern placement variations. Though CD uniformity (CDU) on line pattern in self-aligned double patterning (SADP) is relatively stable caused in high thickness controllability of spacer deposition films, the variations of CDU and LER on first core pattern impinge the CDU on space and pitch pattern. In previous study, pattern fidelity of single exposure patterning was improved through photoresist smoothing process using direct-current superposition technique^[4],[5]. In this paper, we will report that photoresist smoothing work in an efficient way to pattern fidelity control in self-aligned type multiple patterning.