Ultrasonic monitoring of photoresist processing

Susan L. Morton; F. Levent Degertekin; Butrus T. Khuri-Yakub

doi:10.1117/12.350823

14 June 1999 Ultrasonic monitoring of photoresist processing

Susan L. Morton, F. Levent Degertekin, Butrus T. Khuri-Yakub

Proceedings Volume 3677, Metrology, Inspection, and Process Control for Microlithography XIII; (1999) https://doi.org/10.1117/12.350823
Event: Microlithography '99, 1999, Santa Clara, CA, United States

Abstract

A high frequency ultrasonic technique has been developed to monitor photoresist processing in situ during semiconductor manufacturing. Photoresist pre-exposure bake and development have been monitored using the sensor, and the post-exposure bake has been studies as well. The in-situ glass transition temperature (T_g) was determined during the prebake for I-line films down to 0.6micrometers as well as for chemically- amplified DUV resist of similar thicknesses. Using classical reflection theory, photoresist properties such as the density, thickness and acoustic velocity were determined during processing. This in situ parameter inversion method can be used to determine process endpoint if the optimal density, velocity, and thickness are predetermined. The T_g for post-exposure bake of I-line resists is expected to be the T_g of the novolac resin alone, without solvent present. Measurements using the described sensor have confirmed that the resin T_g during postbake is 118 degrees C, the value of T_g provided by Shipley. This provides a measurement of postbake as well as a confirmation that the sensor is measuring T_g accurately. The development process was also monitored using this sensor. Results prove the usefulness of this sensor for in situ measurements of resist thickness changes during development. This was verified for different exposure doses and for resist coated on a wafer with circuit topography.

Citation Download Citation

Susan L. Morton, F. Levent Degertekin, and Butrus T. Khuri-Yakub "Ultrasonic monitoring of photoresist processing", Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999); https://doi.org/10.1117/12.350823

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available