By Topic

Real-Time Control of Photoresist Extinction Coefficient Uniformity in the Microlithography Process

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

3 Author(s)
Tay, A. ; Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore ; Weng Khuen Ho ; Xiaodong Wu

Critical dimension (CD) or linewidth is one of the most critical variables in the lithography process with the most direct impact on device speed and performance of integrated circuits. The extinction coefficient is a photoresist property that can have an impact on the CD uniformity. The extinction coefficient is a measure of the absorption of the photoresist and determines the required exposure dose for printing the features. Hence, nonuniformity in extinction coefficients across the wafer will lead to nonuniformity in the linewidth. This paper presents an innovative approach to the control within wafer photoresist extinction coefficient uniformity. Previous works in this literature can only control the average uniformity of the extinction coefficient. Our approach uses an array of spectrometers positioned above a multizone bakeplate to monitor the extinction coefficient. The extinction coefficient can be extracted from the spectrometer data using standard optimization algorithms. With these insitu measurements, the temperature profile of the bakeplate is controlled in real-time by manipulating the heater power distribution using the conventional proportional-integral (PI) control algorithm. We have experimentally obtained a repeatable improvement in the extinction coefficient uniformity from wafer-to-wafer and within wafer. A 70% improvement in extinction coefficient uniformity is achieved

Published in:

Control Systems Technology, IEEE Transactions on  (Volume:15 ,  Issue: 1 )