Critical dimension controllability evaluation based on process error distribution for 150 nm devices

In this study, the critical dimension (CD) controllability of 150 nm patter ns was evaluated by aerial image simulation. We considered three types of p rocess errors (dose errors, focus errors, and mask CD errors) and evaluated the CD error distribution by calculaling both the CD and the probability f or each of the various combinations of process errors. The effects of high numerical-aperture (NA) KrF exposure on CD controllability were investigate d in detail. In contact hole patterns and line patterns with various pitche s, the CD controllability was significantly improved by increasing the NA, up to about 0.72. However, NA of more than 0.72 does not seem to have furth er significant effects on the CD controllability. We also investigated the CD controllability in ArF exposure. ArF exposure is expected to exhibit bet ter CD controllability for contact hole patterns and line patterns with var ious pitches, even under lower NA conditions than KrF exposure.