A glass precursor resist (GPR) is designed on the basis of an idea of conversion of organosilicon polymer to an inorganic substance by lithographic procedure. Developed chemical amplification resist system is composed of poly (di-t-butoxysiloxane) and a photoacid generator. It has a high sensitivity of 1.6 µC/cm2, a resolution of 0.2 µm and an extremely high O2-RIE durability compared with bottom resist. Exposed film changed into silicate glass, and it was confirmed by IR spectra.