Metallization schemes for dielectric thin film capacitors

A detailed analysis of Pt/Ti, Pt/TiO{sub 2}, and Pt/ZrO{sub 2} electrodes was carried out to develop a bottom electrode stack for sol-gel derived thin films capacitors. For the Pt/Ti stack, the choice of layer thickness and deposition temperature is found to affect adhesion to the SiO{sub 2}/Si substrate as well as the extent of hillock formation and Pt{endash}Ti interaction. By using elevated temperature deposition, Pt films close to 1 {mu}m in thickness can be produced with relatively good adhesion and morphological stability using Ti adhesion layers. In addition, Pt films grown on ZrO{sub 2} and TiO{sub 2} adhesion layers exhibit little morphological change and no degradation in sheet resistance after annealing at 650{degree}C. However, neither ZrO{sub 2} nor TiO{sub 2} are as effective as Ti metal in promoting Pt adhesion. Experiments aimed at establishing a correlation between hillock formation and capacitor yield revealed two important results. First, the behavior of Pt/Ti stacks during annealing in air is markedly different from their behavior during PZT film crystallization. Second, preannealing of the Pt/Ti in air prior to PZT film growth actually improves capacitor yield, even though hillock formation occurs during the preannealing treatment. Implications of these results regarding the role of hillocksmore » in controlling capacitor yield are discussed. {copyright} {ital 1997 Materials Research Society.}« less