Abstract: This invention describes improved apparatus and methods for spin-on deposition of semiconductor thin films. The improved apparatus provides for controlled temperature, pressure and gas compositions within the deposition chamber. The improved methods comprise dispensing of solutions containing thin film precursor via a moveable dispensing device and the careful regulation of the pattern of deposition of the precursor solution onto the wafer. The invention also comprises the careful regulation of deposition variables including dispensation time, wafer rpm, stop time and rates of wafer rotation. In one embodiment, the precursor solution is dispensed from the outer edge of the wafer toward the center. In alternative embodiments, processors regulate the movement of the dispensing arm and the precursor pump to provide an evenly dispensed layer of precursor solution. The invention also describes improved methods for evaporating solvents and curing thin films.