Photosensitive cycloaliphatic-epoxy oligosiloxane was synthesized using a nonhydrolytic sol-gel reaction for the fabrication of thick and thermally stable microstructures with high aspect ratios. Its formation was confirmed by Si-29 and pH nuclear magnetic resonance spectroscopy, small-angle neutron scattering, and Fourier transform infrared spectroscopy. Photocuring of cycloaliphatic-epoxy oligosiloxane resin resulted in a thermally stable epoxy hybrid material (epoxy hybrimer). Micropatterns with a high aspect ratio (>5), an excellent sidewall shape, and low shrinkage were fabricated directly from these materials using a simple photolithographic process. The fabricated micropattern sustained temperatures of up to 250 degrees C. (C) 2008 Wiley Periodicals,