Bonding properties of low-temperature wafer bonding using sub-micron gold particles with different particle sizes

摘要

Low-temperature wafer bonding using sub-micron gold particles was investigated. Wafer-level pattern transfer method has also been developed to enable patterning on wafers with fragile structures such as MEMS devices. Sub-micron Au particle patterns with a width of 20 µm – 60 µm and a height around 20 µm were formed on 100mm-diameter glass wafers by means of wafer-level processing using photolithography and a slurry-filling technique, and then successfully transferred onto Si wafers in ambient atmosphere at a temperature of 150°C and an applied pressure of 20 MPa – 30 MPa. Wafer bonding was performed at 200°C, 100 MPa and exhibited a sufficient tensile strength of 45.8 MPa. A good hermeticity was also confirmed as He leak rate of < 1 × 10⁻⁹ Pa·m³/s. Compression deformation measurement was performed for patterns with different mean particle sizes of 0.3µm and 0.1µm and the performance on a-few-µm surface roughness absorption was demonstrated. Patterns with smaller size particles showed larger deformation, or more ability to absorb surface opography.