Real-time optical characterization of laser oxidation process in bimetallic direct write gray scale photomasks

David K. Poon; Glenn H. Chapman; Chinheng Choo; Marian Chang; Jun Wang; Yuqiang Tu

doi:10.1117/12.647251

1 March 2006 Real-time optical characterization of laser oxidation process in bimetallic direct write gray scale photomasks

David K. Poon, Glenn H. Chapman, Chinheng Choo, Marian Chang, Jun Wang, Yuqiang Tu

Author Affiliations +

Proceedings Volume 6106, Photon Processing in Microelectronics and Photonics V; 61060G (2006) https://doi.org/10.1117/12.647251
Event: Lasers and Applications in Science and Engineering, 2006, San Jose, California, United States

Abstract

DC-sputtered Sn/In and Bi/In bimetallic thin films oxidize and turn transparent under laser exposure. The film's transparency, or optical density (OD), changes smoothly with increasing laser power, from ~3.0OD (unexposed) to <0.22OD (fully exposed). Laser-induced oxidation of bimetallic films can be used to produce direct-write binary and analogue grayscale photomasks. In order to create high quality grayscale photomask and to improve our current laser writing process, requires real time measurement of OD values, and a greater understanding of the laser-induced oxidation process of the bimetallic thin films. An OD measurement system has been developed capable of providing real time optical density and exposure power changes for the bimetallic thin films. Three silicon-based PIN photodiodes were used to monitor the incident and transmitted beams powers, allowing us to measure the OD change as the film oxidizes, giving us a real time measure of the optical density changes of the bimetallic thin film. With this OD measurement system, real time OD data can be used to adjust the laser power to compensate any variations in laser output power, film characteristics and other variations in the laser writing system. Furthermore, with the incident beam focused, we can precisely measure OD level in areas as small as the laser spot size. Exposed Bi/In/O films show an immediate rapid -2OD/ms change in the first 0.5 ms of exposure. However, In/Sn and Zn films show an initial time delay before OD begins to change, and then a less rapid change of -0.56OD/ms or -0.32OD/ms respectively.

Citation Download Citation

David K. Poon, Glenn H. Chapman, Chinheng Choo, Marian Chang, Jun Wang, and Yuqiang Tu "Real-time optical characterization of laser oxidation process in bimetallic direct write gray scale photomasks", Proc. SPIE 6106, Photon Processing in Microelectronics and Photonics V, 61060G (1 March 2006); https://doi.org/10.1117/12.647251

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