Investigation of PZT damage during wafer-level bonding of thermo-piezoelectric cantilevers with CMOS wafers for probe-based data storage

Abstract

Lead zirconate titanate (PZT) degradation during wafer level bonding of thermo-piezoelectric cantilevers with CMOS wafers was investigated for probe-based data storage. We found that the polyimide film which serves as a height adjustment during wafer level bonding between cantilevers and CMOS wafers, caused significant damage in the PZT sensor when the polyimide was coated entirely on the PZT capacitor. With polyimide being hydrogen-rich, Pt served as an active catalyst to decompose H-2 molecules to atomic hydrogen during the bonding process. However, for the sample with a polyimide coating only on the top electrode, degradation was minimized. Therefore, PZT damage was minimized successfully by optimizing the polyimide-coated area during integration.