Comprehensive Investigation of the Commercial ELP-20 Electron-Beam Lithography Resist

TL;DR

This paper studies the ELP-20 resist used in electron-beam lithography, analyzing its properties and performance under different conditions.

Contribution

The study provides a systematic characterization of ELP-20 resist's structural and lithographic behavior.

Findings

ELP-20 resist shows a methacrylate structure similar to PMMA based on Raman spectroscopy.

Film thickness follows a power-law dependence on spin speed with high uniformity.

The resist's sensitivity decreases with increasing electron energy, and its contrast value is energy-independent.

Abstract

A systematic experimental study of the positive-tone resist ELP-20 was conducted, covering its structural properties, film-formation behavior, and response to electron-beam exposure. Raman spectroscopy demonstrated the methacrylate nature of the resist and its spectral correspondence to poly(methyl methacrylate) PMMA, which enabled direct comparison both with PMMA itself and with existing methacrylate-based resists. Spin-coated films prepared from 3–11 wt.% solutions exhibited a robust power-law dependence of thickness on spin speed, h∞ ∝ ω−0.48 ± 0.01, and showed high thickness uniformity. The concentration dependence of the film thickness at a fixed spin speed allowed identification of the polymer–coil overlap region and enabled estimation of the effective molecular weight of the polymer base, Meff = (25 ± 7) kg/mol. Lithographic characterization indicated a decrease in sensitivity with increasing electron energy, with a sensitivity of approximately 40 μC/cm2 at 25 keV. A depth-dependent dose-distribution model provided an energy-independent average contrast value of γ ≈ 1.67. The results present a coherent and systematic description of ELP-20 behavior under electron-beam exposure and establish a basis for its further use in lithographic processing.

Figures