Mask Defect Printability and Wafer Process Critical Dimension Control at 0.25 µm Design Rules

In this paper, the effect of mask defects in a wafer process is studied by taking into account the wafer process critical dimension ( CD ) variability. We found that trade-offs between the wafer CD control specification, the actual wafer CD controllability, and the mask defect size requirement exist. We also developed a new statistical explanation for the printable mask defect size which is related to the wafer process specifications and the actual wafer process CD controllability. Based on our statistical assessment, any small mask defect is printable with a given failure rate. The advantages of our data analysis methods can be summarized as follows. 1. The printing effect for a given mask defect size can always be extrapolated even though that defect size is not present on the mask. The defect printability can be redefined without any additional data collection when the process control or the process specification is changed. 3. Information relative to data collection is maximized. 4. The defect printability risk analysis is tied to the process control and the process specifications.