Dry etching rate of electron-beam-exposed negative resists

A method using oxygen plasma treatment to remove successively-electron-exposed negative resist is proposed. The change in resist thickness with plasma treatment time depends on the different doses and the method of exposure. The resulting curves are very similar to the dissolution curves of positive resist. The etching rates in the depth of the exposed resist show that the top edge of the resist is less sensitive to dose changes than the bottom edge. The theoretical models for energy distribution in the resist film support such assumptions. The experimental data could be useful for more correct modelling and profile simulation of electron-exposed negative resists.