Silicon-rich suboxide (SiOx, x < 2) films with oxygen content (x) ranging from 1.0 to 1.9 were deposited by plasma enhanced CVD on a silicon substrate. Successive annealing at various temperatures was carried out to form Si nanoparticles embedded in a SiO2 matrix. FTIR was used for monitoring the process. From HRTEM observation, Si quantum dot size is tunable for different initial composition and annealing temperature. As-deposited suboxide films exhibited strong photoluminescence which was quenched after high temperature anneals.