Conducting polyanilines: Discharge layers for electron-beam lithography

This paper describes the use of electrically conducting polyanilines as discharge layers for electron-beam (e-beam) lithography. The emeraldine oxidation state polyaniline is a soluble material which can be doped by various cationic reagents, most commonly protonic acids, to afford conductivity on the order of 10° Ω−1 cm−1. The conducting polyanilines are incorporated as thin interlayers (2000 Å) in a multilayer resist system consisting of a planarizing underlayer (2.8 μm) and the imaging resist (1.2 μm) on top. We find that various acid-treated polyanilines eliminate charging during e-beam patterning of the resist, i.e., zero pattern displacements are observed as compared to the case where a conducting interlayer is not incorporated into the resist system. In the latter case placement errors greater than 5 μm are observed as a result of charging. A minimum conductivity of 10−4 Ω−1 cm−1 is required for the polyaniline interlayers in order to observe zero pattern displacement. In addition, we have simplified the doping reaction for polyaniline by inducing the conductivity photochemically or by e-beam exposure with the use of onium salts. This process resulted in the development of a new photo and e-beam conducting resist material.