High Quality Pt–Pt Metal Bonding for High Temperature Packaging

Abstract

Platinum is an ideal material for high-temperature resistant device packaging due to its higher melting point and good electrical properties. In this paper, the thermocompression bonding of Pt–Pt metal electrodes was successfully realized through process exploration, and the package interconnection that meets the requirements was formed. A square bump with a side length of 160 µm and a sealing ring with a width of 80 µm were fabricated by magnetron sputtering. Different pressure parameters were selected for chip-level bonding; the bonding temperature was 350 °C for about 20 min. Analysis of the interface under a scanning electron microscope found that the metal Cr diffused into Pt. It was found that two chips sputtered with 300 nm metal Pt can achieve shear resistance up to 30 MPa by flip-chip bonding at 350 °C and 100 MPa temperature and pressure, respectively. The leakage rate of the sample is less than 2 × 10–3 Pa·cm3/s, the bonding interface is relatively smooth, and the hot-pressed metal bonding of Pt electrodes with good quality is realized. By comparing the failure rates at different temperatures and pressures, the process parameters for Pt–Pt bonding with higher success rates were obtained. We hope to provide new ideas and methods for the packaging of high-temperature resistant devices.