Defect Gallery and Bump Defect Reduction in the Self-Aligned Double Patterning Module

The self-aligned double patterning (SADP) module is a scheme to form 32 nm or 22 nm line structures that extend the useful range of either dry scanner or immersion scanner photolithography tools. Once reliable baseline processes for SADP flow have been developed, defect data collection, understanding, characterization, and reduction become increasingly important. Knowledge on defect characterization and reduction thus obtained reduces tool ramp-up time at manufacturing sites and provides new directions to improve wafer fabrication processes. In this paper, the types of defects in each step of the process to ultimately form 32 nm or 22 nm structures using the SADP flow are discussed, including an in-depth study of the impact of bump defects on the SADP flow, and proposed mechanisms of bump defect formation. Potential solutions involving an improved film deposition process for the SADP process module are also presented.