From 1D-spot to 2D-plain: a computer vision-based comprehensive approach for process window qualification

Process Window Qualification (PWQ) is an essential phase in the semiconductor manufacturing process. The Focus Exposure Matrix (FEM) is the most prevalent technique employed within PWQ. Traditionally, the method relies on spot features, such as Critical Dimensions (CD), and utilizes the Bossung curve for PWQ. However, with intricate circuit layouts and multi-step processes, such as Litho-Etch-Litho-Etch (LELE) sequences, the conventional approach struggles to account for all possible conditions. To address this, we propose an innovative computer vision-based approach for PWQ. Taking the CD as an example, instead of merely measuring the CD of selected patterns, our method scans the entire circuit layout to identify areas prone to defect such as bridge or broken, thereby leading to a more accurate and objective PWQ.