Study on Lithography Defect Reduction for 19nm NAND SADP Process
Guangchi Ying, Yunqing Dai, Jian Wang, Hongzhu Zheng · 2021
With the dimension of NAND flash reaching the limit of ArF 193nm immersion scanner by single exposure at half pitch 38nm, the SADP technology (Self Aligned Double Patterning) is utilized to achieve 19nm half pitch CD. However, with the line CD shrinking and cell density increasing, the line broken defects and block etch defects, which are resulting from lithography processing, come to be the key yield killer definitely. In this paper, the defect reduction methodology of HLMC 19nm NAND SADP lithography process, including the line broken defects and block etch defects, is summarized by theoretical analysis and tested by experiment results. The defects are eliminated by RRC pre-clean and enhanced rinse after development, which helps to realize 19NAND mass production and yield improvement, and benefits to more advanced technology nodes development as well.