Epitaxial α-quartz films could enable the fabrication of sensors for prospective applications. However, a prerequisite is to tailor α-quartz microstructures at the nanoscale. My PhD works bring new insights into the devitrification of silica into epitaxial α-quartz films on Silicon(100) and reveal how to control the film microstructure: It shows that by increasing the quantity of devitrifying agent (Sr), one can switch from an α-quartz microstructure consisting of porous flat film to a microstructure dominated by dense α-quartz crystals. Besides, other parameters such as film thickness, relative humidity and surfactant also can play important roles in microstructural control of films. Moreover, via a multilayer deposition method, film thickness can be extended to the micron range, which enable nanosructuring by lithography.