Contact Photolithography at Sub-Micrometer Scale Using a Soft Photomask.

Chun-Ying Wu,Heng Hsieh,Yung-Chun Lee

doi:10.3390/mi10080547

Abstract

This paper proposes a method for improving the patterning resolution of conventional contact photolithography from the micrometer, down to the sub-micrometer scale. The key element is a soft polydimethylsiloxane (PDMS) photomask, which is first replicated from a silicon mold and then patterned with a black photoresist (PR) layer to selectively block ultraviolet (UV) light. This soft PDMS photomask can easily form an intimate and conformable contact with a PR-coated substrate and hence can perform contact photolithography with high pattern resolution. The fabrication processes of this black-PR/PDMS soft photomask are experimentally carried out. Using the fabricated soft photomask, UV patterning by contact photolithography with the smallest line-width of 170 nm over a 4” wafer area was successfully achieved. The advantages and potentials of this new type of contact photolithography will be addressed.

Highlights

Photolithography technologies have been successfully developed in the past few decades and are the most mature and dominant method for micro- and nanofabrication in the industry [1,2,3,4].There are basically two categories of photolithography
To investigate the capabilities of sub-μm scale UV patterning using the black-PR/PDMS soft molds, an 8” silicon mold was first fabricated by a local semiconductor foundry
We demonstrated how to bring the patterning resolution of contact photolithography currentwe status of 1 μm, downhow to the to order of 100the nm. patterning

Summary

Introduction

Photolithography technologies have been successfully developed in the past few decades and are the most mature and dominant method for micro- and nanofabrication in the industry [1,2,3,4].There are basically two categories of photolithography. Photolithography technologies have been successfully developed in the past few decades and are the most mature and dominant method for micro- and nanofabrication in the industry [1,2,3,4]. One of the most important advantages of projection photolithography is its high resolution and a line-width down to a few tens of nanometer can be achieved nowadays in the semiconductor industry [5,6]. Both capital investments and running costs for projection photolithography are very high, which limits its availability and makes it less accessible to general users

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Conclusion