Evaluating the probabilistic process window for use in high volume manufacturing

Background: Process window metrology is used in manufacturing to determine best dose and focus for the scanner, but current metrology uses defect inspection to determine best focus and thus is expensive and time consuming. Aim: Ideally, an alternate stochastics metric (such as linewidth roughness for line/space patterns) could be used as a substitute for defectivity measurements, saving time and money. Approach: Here, the Probabilistic Process Window (PPW) is evaluated as an improved alternative to the plan of record approach, where only CD-SEM images are collected and evaluated. Results: The PPW was found to provide results that matched to the plan of record approach, but with increased rigor and improved precision. Conclusions: As a result, critical layers on future DRAM manufacturing nodes will use the PPW for best dose/focus scanner control.