Polymethyl Methacrylate as an Electron Sensitive Resist

Abstract

The use of radiation-sensitive polymer materials for etch-resistant masks is a necessary feature of the material processing stage of semiconductor device manufacture. PMMA is currently used by most workers investigating electron beam exposure techniques, no preferable polymer having been found to date. This paper describes the importance of the MWD of PMMA in determining its performance as an electron-sensitive resist. All experimental mol. wt data has been obtained using Gel Permeation Chromatography. It is shown that the glass transition temperature of PMMA (typically 100 to 110 C) is suitable for its use as a resist and electron sensitivity is good. Adhesion of films to substrates is generally satisfactory and may be improved considerably by polymer hydrolysis. However spin coating characteristics, pattern resolution and etch resistance are dependent on the MWD.