In electron-beam lithography, charging on the photoresist usually causes image distortion and placement error. To dissipate the charge, a conductive polymeric layer can be introduced either over or under the photoresist coating. In this paper, we will discuss the approach of using toluene and xylene-soluble poly(alkylthiophene) in combination with a photoacid generator as a discharge underlayer or interlayer beneath the photoresist to dissipate the accumulated charge during electron-beam exposure. We will also discuss the use of water-soluble acid or ammonium salt forms of polyl-3-(ethanesulfonate)thiophene] as the discharge top layer. During the resist image developing process, the top layer will be removed by aqueous base. Therefore, it is advantageous to use a discharge top layer owing to its simplicity. In this study, the salt and acid forms ofpoly[3-(ethanesulfonate)thiophene] were synthesized through chemical polymerization of the corresponding methanesulfonate ester. They exhibit the same properties as those of electrochemically synthesized polymer reported in the literature.
Посилання на статтю:
Synthesizing and processing conducting polythiophene derivatives for charge dissipation in electron-beam lithography / Wu-Song Huang // Polymer. – 1994. – Vol 35. – P. 4057-4064.