Planarizing material for reverse-tone step and flash imprint lithography

Tsuyoshi Ogawa,C Grant Willson,William Bell,Satoshi Takei,Yuji Hagiwara,B Michael Jacobsson,Michael W Lin,Makoto Hanabata,Ryan Deschner

doi:10.1117/1.jmm.13.3.031302

Abstract

Reverse-tone step and flash imprint lithography (S-FIL/R) requires materials that can be spin-coated onto patterned substrates with significant topography and that are highly planarizing. Ideally, these planarizing materials must contain silicon for etch selectivity, be UV or thermally curable, and have low viscosity and low volatility. One such unique material, in particular, a branched and functionalized siloxane (Si-12), is able to adequately satisfy the above requirements. This paper describes a study of the properties of epoxy functionalized Si-12 (epoxy-Si-12) as a planarizing layer. An efficient synthetic route to epoxy-Si-12 was successfully developed, which is suitable and scalable for an industrial process. Epoxy-Si-12 has a high silicon content (30.0%), low viscosity (29 cP at 25°C), and low vapor pressure (0.65 Torr at 25°C). A planarizing study was carried out using epoxy-Si-12 on trench patterned test substrates. The material showed excellent planarizing properties and met the calculated critical degree of planarization (critical DOP), which is a requirement for a successful etch process. An S-FIL/R process using epoxy-Si-12 was demonstrated using an Imprio® 100 (Molecular Imprints Inc., Austin, Texas) imprint tool. The results indicate that epoxy-Si-12 works very well as a planarizing layer for S-FIL/R.

Highlights

S-FIL has a strong advantage over extreme ultraviolet (EUV) and other proposed optical lithography processes in terms of cost of ownership.[4,5]
The step and flash imprint lithography (S-FIL/R) process is superior to traditional S-FIL because of a much wider process window and a possibility to yield high aspect ratios.[7]
S-FIL/R requires an additional layer, a planarizing layer with high silicon content that is resistant to an O2 plasma etch

Summary

Introduction

Step and flash imprint lithography (S-FIL®) is one of the candidates for the fabrication of nanoscale structures such as patterned media, MEMS devices, and IC devices.[1,2,3] S-FIL has a strong advantage over extreme ultraviolet (EUV) and other proposed optical lithography processes in terms of cost of ownership.[4,5] This is because there is no need for costly optics and an expensive light source. The first is a traditional imprint process (S-FIL) and the other is a reverse-tone S-FIL process called S-FIL/R. The S-FIL/R process is superior to traditional S-FIL because of a much wider process window (high tolerance to a variety of topographic surfaces, which solves the residual layer uniformity and thickness issues) and a possibility to yield high aspect ratios.[7] S-FIL/R requires an additional layer, a planarizing layer with high silicon content that is resistant to an O2 plasma etch. This paper describes the development of such a planarizing material

Methods

Results

Conclusion