Manufacturing Cost Saving Through Reduced Metrology Using Time Series Analysis

Inline metrology is critical in providing data used in advanced process control (APC) control loops. However, fabs benefit from running with as few metrology tools as possible while meeting quality and control requirements. This paper uses time series analysis to show the relationship between sampling rates and closed-loop variance of feedforward and feedback-controlled processes. The approach was used in GlobalFoundries’ Fab8, in Malta NY, to identify opportunities for reduced process sampling. A 7% reduction in metrology was achieved at a critical toolset, making it possible to avoid capital expenditure, improved overall cycle time, and reduced per wafer measurement cost.