Photo-resist dispensers traditionally apply a generous amount of resist on the wafer and then spin the wafer to reach a uniform desired thickness. With this technique, over 95% of expensive and hazardous liquid is wasted. The goal of this project is to reduce the waste by using a drop-on- demand ejection technology to apply the photo-resist. In practice, a controller turns out to be necessary to compensate for the variability of the performance of the ejectors, to insure the stability of the ejection, and to speed up the transient regime for drop-on-demand operation. The paper reports on the design and simulation of this controller.

Date Published: 24 July 1998
PDF: 9 pages
Proc. SPIE 3323, Smart Structures and Materials 1998: Mathematics and Control in Smart Structures, (24 July 1998); doi: 10.1117/12.316324

Published in SPIE Proceedings Vol. 3323:
Smart Structures and Materials 1998: Mathematics and Control in Smart Structures
Vasundara V. Varadan, Editor(s)