Showing papers by "U-In Chung published in 1999"

Automatic in-situ focus monitor using line-shortening effect

Abstract: A new focus monitoring method, AIFM has been developed. Specially designed box-in-box was drawn on conventional Cr binary mask and investigate. The box-in-box were drawn to enlarge the line end shortening effect in this new method. There is a lateral shift between inner and outer box in printed feature, and it can be measured quickly at a number of locations across the field and across the wafer with a common overlay measurement system. AIFM provides a means of evaluating focus effects such as field curvature, astigmatism, and field tilt like other focus measurement method. This method has another advantage of in-situ process condition monitoring by drawing focus monitor patterns in real product masks. Experiments were performed to evaluate the effects of pattern geometry and exposure dose on the sensitivity of the focus monitor. AIFM data shows good correlation with conventional focus measurement using SEM line width measurement.

Plasma charge-induced corrosion of tungsten-plug vias in CMOS devices

Abstract: Plasma charge-induced corrosion of tungsten plug vias, where part of the via surface is exposed to the chemical solution after metal-2 etch by photolithographic misalignment with upper metal lines, was investigated. Some electrochemical tests and plasma damage monitoring were done to study the corrosion mechanism. The configuration of circuits was also investigated to understand the pattern dependency of the plasma damage and the corrosion. It is believed that the positive charges on the metal lines and P/sup +/ active region of the PMOS, developed during dry etching and ashing, are enhancing the corrosion of tungsten during stripping. The plasma-less O/sub 3/ asher applied to the ashing process reduced the plasma damage and did not produce empty vias on the wafer.