Novel two-step baking process for high-aspect-ratio photolithography with conventional positive thick photoresist

Jun-Bo Yoon; Chul-Hi Han; Euisik Yoon; Choong-Ki Kim

doi:10.1117/12.324074

1 September 1998 Novel two-step baking process for high-aspect-ratio photolithography with conventional positive thick photoresist

Jun-Bo Yoon, Chul-Hi Han, Euisik Yoon, Choong-Ki Kim

Author Affiliations +

Proceedings Volume 3512, Materials and Device Characterization in Micromachining; (1998) https://doi.org/10.1117/12.324074
Event: Micromachining and Microfabrication, 1998, Santa Clara, CA, United States

Abstract

We have developed a novel two-step baking process to achieve high-aspect-ratios in UV photolithography with a conventional positive thick photoresist. We newly report high-aspect-ratio (greater than 10:1) results in a single coated 91 micrometer- thick photoresist AZ9262, which was introduced Hoechst at SPIE in 1996. From extensive experiments, we improved the aspect ratio by minimum exposure, diluted development, reabsorption of sufficient water before exposure, and especially by extended and effective soft bake in two steps. In the optimum two-step baking, first the baking is performed at an intermediate temperature in a forced convection oven for hours to evaporate large amounts of solvent. Second, the photoresist is heat-treated at an elevated temperature on an air-gapped hotplate with cover for minutes to enhance aspect ratios. The reason for this improvement has been studied based on the photochemical process of the DNQ/novolac-type positive photoresist. Using this two-step baking, we have obtained lines of 4.4 micrometer-wide bottom in a single coated 91 micrometer-thick photoresist (aspect ratio: 20). The line width in the mask was 8.9 micrometer, and hence 2.2 micrometer undercut was observed.

Citation Download Citation

Jun-Bo Yoon, Chul-Hi Han, Euisik Yoon, and Choong-Ki Kim "Novel two-step baking process for high-aspect-ratio photolithography with conventional positive thick photoresist", Proc. SPIE 3512, Materials and Device Characterization in Micromachining, (1 September 1998); https://doi.org/10.1117/12.324074

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