Wafer CD Uniformity Improvement in Negative Tone Development Process

WCDU (wafer critical dimension uniformity) has become one of the most momentous factors in the resist process for mass production. Non-uniform WCDU, CD value changes from wafer center to edge, can occur in resist process despite tight critical dimension uniformity (CDU). In this paper, the resist components and the resist process conditions that influence on WCDU variation in negative tone development (NTD) process will be discussed. WCDU was measured with various parameters to understand the causes of current performance.