Coating uniformity and device applicability of spin coated sol-gel PZT films

Important coating characteristics are discussed with an emphasis on understanding their impact on device reliability. The sources of thickness variations in relationship to the processing conditions imposed during spin coating and subsequent firing are described. In particular, evaporation of volatile solvents during spinning can cause thickness striations and vacuum-chuck marks. In addition, the crystallized microstructure may not be completely uniform, depending on the uniformity of substrate nucleation locations. These variations will impact the electrical reliability of the PZT devices which are made from these films. Thinner regions will have higher capacitance, but will be more susceptible to electrical degradation over time. Also, the scale of size uniformity in the microstructure can impact attempts to make smaller devices.