| dc.description.abstract | 3D IC can reduce the signal transmission path, vertical current conduction and uniform current by vertically stacking to enhance signals. In order to avoid the reliability problems of using a solid-liquid system at high bonding temperature to cause the brittle IMC formation at the joints in 3D IC, low-temperature solid-state interdiffusion bonding is a key technology. However, the common Cu-Cu diffusion bonding is easy to oxidize during the process, resulting in poor quality. Therefore, an anti-oxidation layer is needed. Pd is hard to oxidize and form solid solution with Cu. Further, in order to effectively reduce the bonding temperature, uniaxial stress is applied to the materials during the bonding process; however, comparing with the hydrostatic pressure which has been extensively studied in the past, the effect of uniaxial axial stress is rarely mentioned. Therefore, the uniaxial axial stress effect has high research values for promoting the phenomenon of interdiffusion to achieve a good bonding interface at low temperature. First, the Pd is metallized on the electro-plated Cu (220) by evaporation deposition, and placed in the special graphite cell with 0 MPa, 125 MPa, and 250 MPa in vertical direction. Through Ar ion etching and XPS element analysis, we can obtain the Pd/Cu interdiffusion depth distribution in different temperature and uniaxial axial stress, and use the Boltzmann-Matano methods to obtain the interdiffusion coefficients. Then, the relationship between the energy difference between (1) Erying equation ground state and activated state and (2) the 3-D harmonic oscillation of atoms in solid crystals are introduced into the diffusion behavior for discussion. The activation enthalpy and entropy obtained from the experiments can be used to predict the interdiffusion behavior of low temperature solid solutions by uniaxial axial stress and temperature effects through the regression of the difference in kinetic energy and vibrational entropy between the ground and the saddle state.
In the GaN LED reliability problems, due to the heat production from the solid-state bonding process and device working, the reflectance of plated Ag lead frame would decrease dramatically. We use Zn and Sn alloy with Ag in evaporation deposition, and discuss the effects of the oxide composition on (1) the resistance of reflectance decay by the element concentration analysis and peak separation on the Ag and Ag(Zn/Sn) surface and (2) the copper flux in the Ag and Ag(Zn/Sn) alloy layer by calculated the XPS depth element concentration distribution and peak splitting. | en_US |