Thin films of heteroepitaxial yttria-stabilized zirconia (YSZ) have been deposited by electron cyclotron resonance assisted-reactive sputtering on Si(100) substrates. The initial stages of film growth on the bare Si surface were determined to be critically important for the resulting quality of the crystalline film. The benefits of low energy ion bombardment to enhance the growth process were measurable at 650 degrees C, but could not compete with the crystal quality of the material grown at 800 degrees C. A 1050 degrees C postdeposition anneal step using a variety of gas ambients improved crystalline quality of the deposited material. The crystalline quality of the annealed material was independent of the as-deposited material quality. This can be significant for those attempting to grow heteroepitaxial YSZ films at reduced substrate temperature. The reason for the improvement in crystalline quality is believed to be the reduction of stresses existing at the SiO2/YSZ interface. The X-ray diffraction results indicate that the YSZ material film deposited by this technique is currently of the highest quality obtained by any technique to date.