Sub-20-nm tip-to-tip enabled by anti-spacer patterning

Alternative patterning solutions, such as spacer-based pitch splitting, have been a cornerstone of advanced technology nodes to enable device scaling. The greatest utility comes from the ability to self-align a pitch splitting process; however, traditional spacer-based patterning techniques require the deposition and etch of multiple materials, which reduce throughput and increase manufacturing costs. Anti-spacer technology, on the other hand, enables both self-aligned pitch splitting and high throughput via a single pass track-based process. We will describe the advancement of 193i anti-spacer technology to pattern trench dimensions beyond the critical dimension resolution of single-print extreme ultraviolet lithography and the utility of combining anti-spacer patterning with litho-freeze-litho-etch to enable the formation of sub-20-nm slot contact features for a minimum tip-to-tip (T2T) cut, with a roadmap to achieve sub-12 nm. A through process performance evaluation was conducted to further the understanding of fundamental process parameters and their associated effects on anti-spacer roughness and critical dimension uniformity. Such variables include photoresist, developer optimization, and overcoat dissolution. At pitches varying from 50 to 80 nm, we have demonstrated narrow trench widths down to 11.8 nm, which corresponds to the critical T2T dimension. Through hardmask etch transfer, we observe a 56% improvement in unbiased space width roughness and pitch-walking below 0.3 nm at 60-nm pitch.