Optimum sampling for characterization of systematic variation in photolithography

Abstract

In this paper, variability in the photolithography pattern transfer process is analyzed by means of a large number of CD measurements spread across the stepper field and across the wafer. The variability is found to be highly systematic in nature, and methods are developed to extract the parameters of this systematic variation. Knowledge of the structure of the systematic variance allows for the selection of an optimum sampling plan to best capture the variance in future measurements of wafers from the same process.

Impact of Process Variations on Multicore Performance Symmetry

“…These circular areas may vary in their area, location, and magnitude. Our modeling methodology differs since our pattern of variation is based on measured data from [6,13].…”

“…In order to estimate the possible magnitude of C2C asymmetry, we develop a model based on the pattern and magnitude measured by Cain [6]. We assume that the chief source of systematic WID variation is variability in effective gate length (L e f f ) due to optical variations across the exposure field.…”

Parameter variation sensing and estimation in nanoscale fabrics

“…In addition, to address the aspect of sensor distribution across a wafer, sensor effective range is defined based on spatial correlation. In conjunction with well-characterized experimental data shown in [22], the sensor effective range is calculated with respect to different values of permissible error. Our results show that the sensor design can estimate the extent of systematic variation in the gate diameter to within 20% of its actual values inside a 3.3mm radius based on the given experimental data.…”