Effects of electron beam irradiation on highly oriented poly(di-methyl silane) film

The effects of electron beam irradiation on highly oriented poly(di-methyl silane) film are studied. The highly oriented films, in which the silicon backbone of poly(di-methyl silane) is perpendicular to the substrate surface, are prepared by means of a vacuum-evaporation technique. The orientation of the polysilane is confirmed by ultraviolet absorption and x-ray diffraction measurements. By electron beam irradiation, the polysilanes in the film are bonded with the nearest neighbour chains by forming C-O-C, Si-O-C, and/or Si-O-Si groups, which are investigated using Fourier transform infrared spectroscopy. The irradiated part of the film is hardened, and remains on the substrate after etching by concentrated H2SO4, whereas the other part is completely removed. By using such a process, a negative-tone pattern having sufficient resistance against acid can be obtained. The possibility of the application of this effect is also discussed on the basis of the microscopic structure of the present film. (author)