Study of organic polymer thin-film etching by plasma beam irradiation

Abstract

We investigated the etching characteristics of three kinds of methacrylate polymer films which have the same main chain with a different side chain using a plasma beam irradiation apparatus. The polymers are polytbutylmethacrylate (PtBuMA), polybenzylmethacrylate (PBMA), and polycyclohexylmethacrylate (PCHMA). The etch yield (EY) of PtBuMA was higher than those of the others in the case of N2 plasma beam. The EYs of PBMA and PCHMA increased with an increase in the ion energy of up to 330eV and saturated at over 330eV. On the other hand, that of PtBuMA was almost constant at the ion energy higher than 130eV. It was supposed that nitridation of the polymer plays an important role in the enhancement of etching by N2 plasma. In the case of Ar plasma, EY increased linearly with an increase in the square root of ion energy for every polymer. In the case of H2 plasmas, EY scarcely depended on the ion energy regardless of the polymers. Etching behaviors with Ar and H2 plasma irradiation showed physical sputtering and chemical sputtering, respectively. The order of the magnitude of EY was PtBuMA, PCHMA, and PBMA for all of the Ar, H2, and N2 plasmas.