Wafer-Level Hermetic Bonding Using Sn/In and Cu/Ti/Au Metallization

Abstract

Abstract-Low-temperature hermetic wafer bonding using In/Sn interlayer and Cu/Ti/Au metallization was investigated for microelectromechanical systems packaging application. In this case, the thin Ti layer was used as a buffer layer to prevent the diffusion between solder interlayer and Cu after deposition and to save more solders for diffusion bonding process. Bonding was performed in a wafer bonder at 180 and 150 C for 20 min with a pressure of 5.5 MPa. It was found that bonding at 180 C voids free seal joints composed of high-temperature intermetallic compounds were obtained with good hermeticity. However, with bonding at 150 C, voids were generated along the seal joint, which caused poor hermeticity compared with that bonded at 180 C. After four types of reliability tests-pressure cooker test, high humidity storage, high-temperature storage, and temperature cycling test-dies bonded at 180 C showed good reliability properties evidenced by hermeticity test and shear tests. Results presented here prove that high-yield and low-temperature hermetic bonding using Sn/In/Cu metallization with thin Ti buffer layer can be achieved.Index Terms-Hermeticity, In-Sn, microelectromechanical systems (MEMS), reliability, wafer bonding, wafer-level packaging.

Heterogeneous Wafer Bonding Technology and Thin-Film Transfer Technology-Enabling Platform for the Next Generation Applications beyond 5G

“…Wafer bonding is a popular technology that can integrate two or more kinds of materials into one heterogeneous system. It has been successfully applied to system-in-package (SiP) and fabrication of heterogeneous structures [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ]. Traditional wafer bonding technology is mainly based on silicon (Si)-based materials and is oriented to the microelectromechanical system (MEMS) packaging [ 8 , 9 , 10 ].…”

Progress in wafer bonding technology towards MEMS, high-power electronics, optoelectronics, and optofluidics

“…Wafer bonding technology which can integrate multiple kinds of active and passive devices into a system is popular in the device packaging for the integrated circuit (IC) and micro-electromechanical system (MEMS). [1][2][3][4][5][6] Many bonding methods have been developed for joining homo/ heterogeneous materials. [7][8][9] According to the intermediate layer is introduced or not during the bonding procedure, the bonding technology can be divided into two categories.…”