An in-line process monitoring method using electron beam induced substrate current

In-line process monitoring technology plays a vital role in accelerating yield ramps and quickly identifying and resolving yield excursions in the system on a chip era. We have developed an in-line process monitoring method that uses electron beam induced substrate current. It is especially suitable for deep contacts and via holes. This method makes it possible to monitor non-destructive contacts and the via-hole formation process with a hole-bottom nm-order SiO2 film thickness measurement and a hole-bottom diameter measurement. Moreover, it allows us to evaluate etching-process variation over an 8-inch wafer in less than 20 min. The results can be used for in-line device sorting as well as for decisions regarding the timing of etching machine maintenance. (C) 2001 Elsevier Science Ltd. All rights reserved.