No abstract

The impact of process parameters on final bonding layer quality was investigated for Transient Liquid Phase (TLP) wafer-level bonding based on the Cu-Sn system. Subjects of this investigation were bonding temperature profile, bonding time and contact pressure as well as the choice of metal deposition method and the ratio of deposited metal layer thicknesses. Typical failure modes in Inter-Metallic Compound (IMC) growth for the mentioned process and design parameters were identified and subjected to qualitative and quantitative analysis. The possibilities to avoid abovementioned failures are indicated based on experimental results.

Cu-Sn Transient Liquid Phase (TLP) wafer-level bonding is an interesting solution for wafer-to-wafer stacking technologies, due to its compatibility with 3D interconnections as well as vacuum sealing applications. The work presented here is analysing typical Cu-Sn TLP wafer bonding issues as occurrence of voids, bonded wafers pair bow and incomplete layer transformation with respect to process parameters as maximum bonding temperature, bonding time and contact (bonding) pressure.

The working principle of various categories of MEMS devices require inside the packages the encapsulation of vacuum ambient which impacts on device performance. The factors impacting on process choice will be reviewed. Main wafer bonding processes used for such applications will be introduced.