Resist Requirements for Electron Projection and Direct Write Nanolithography

摘要

This paper will discuss aspects of resist properties required for nanolithography using high-energy electrons. A comprehensive image formation model is presented for positive and negative chemically amplified resists where most aspects have been considered (from exposure through development) for e-beam nanolithography (EPL, DWL). A series of optimization studies are performed using the modulation of soluble site density after PEB as a metric to characterize resist imaging performance. Base loading, blocking fraction and acid diffusion properties are investigated. Slower acid diffusion near regions with deprotected sites dominates during PEB and contributes to a sharp image modulation. Electron beam exposed nanostructures exhibit spatial fluctuations of soluble sites in the material left after development, which may alter etch resistance and pattern collapse. Soluble site fluctuations arise from the low statistics involved in the image formation and are significant contributors to the sidewall roughness.