Chemical and physical aspects of multilayer resist processing

Abstract

A multilayer resist structure is typically composed of at least two materials, an oxygen plasma resistant layer and a planarising layer which is eroded in an oxygen based plasma. This structure is then subjected to a variety of excited and ground state species generated in the plasma. To understand the final etched profile produced by such a system, it is necessary to characterise both the chemical nature of the plasma, and its impact upon the structure subjected to the etching process. This paper will discuss the effect of the intrinsic plasma properties such as composition, density, potential and electron energy distribution upon the processes which produce etching of both the planarising and etch resistant layers. The effect of the chemical composition of organometallic etch barriers based on silicon, germanium and iron and the process by which they resist these plasmas will also be presented and compared with the properties of the planarising layers. The etching properties of the planarising layer will be shown to depend strongly upon the plasma excitation frequency. © 1988 SPIE.