Room Temperature Wafer Bonding of Glass Using Aluminum Oxide Intermediate Layer

This paper presents a room temperature bonding technique of glass substrates with a transparent bonding interface. As a room temperature bonding method, surface activated bonding (SAB) is applied for the bonding of glass using Si intermediate layer. However, the bonding interface is colored by the deposited Si layers, which leads to lower applicability to optical devices. In this study, a new concept of SAB is developed using aluminum oxide intermediate layer. Glass substrates are successfully bonded at room temperature via the aluminum oxide intermediate layers activated by Ar ion beam irradiation, showing a bond strength of 1.32 J m−2. It is also shown that the optical characteristics at the interface such as transparency and reflectance are not degraded, while the bonding interface of the SAB using Si intermediate layer deteriorates. The XPS and STEM-EDX analyses indicate that the bonding is achieved through the amorphous and O-deficient aluminum oxide interface. This technique will provide a transparent interface for glass bonding by a room temperature process, which is highly desired in optical device fabrication.