COATING UNIFORMITY AND DEVICE APPLICABILITY OF SPIN-COATED SOL-GEL PZT FILMS

Important coating characteristics are discussed with an emphasis on un derstanding their impact on device reliability. The sources of thickne ss variations in relationship to the processing conditions imposed dur ing spin coating and subsequent firing are described. In particular, e vaporation of volatile solvents during spinning can cause thickness st riations and vacuum-chuck marks. In addition, the crystallized microst ructure may not be completely uniform, depending on the uniformity of substrate nucleation locations. These variations will impact the elect rical reliability of the PZT devices which are made from these films. Thinner regions will have higher capacitance, but will be more suscept ible to electrical degradation over time. Also, the scale of size unif ormity in the microstructure can impact attempts to make smaller devic es.