Low-temperature fusion bonding of aluminosilicate glass via intermediate water

Abstract

Aluminosilicate glass holds significant importance across various applications including display screens, medical devices, and the aerospace industry, owing to its excellent optical properties, superior strength, and chemical resistance. Compared with frequently used high-temperature fusion bonding, low-temperature direct glass bonding, with its potential for reliable, non-damaging fabrication of glass-based devices, is highly promising. However, achieving aluminosilicate glass bonding at a low temperature has remained a challenge due to its inherent chemical stability. This paper proposes a novel low-temperature fusion bonding method using a standard cleaning recipe assistant with intermediate water, resulting in bonding strength exceeding 10 MPa and optical transmittance surpassing 90 % at a moderate annealing temperature of 200 °C. Through surface and interface characterization, the role of water intermedia and bonding mechanism is analyzed and declared. The water trapped in the bonding interface reacts with the glass and lowers the glass transition temperature (Tg), softening the glass and filling the nanoscale gaps to further increase the bonding area in the low-temperature annealing process. Consequently, a continuous bonding interface is established, contributing to robust bonding strength and avoiding optical loss. Finally, this method is further demonstrated through the successful bonding of the glass with grating structures showing great optical properties. Notably, in contrast to traditional fusion bonding, this low-temperature fusion bonding method will not destroy the microstructures in the devices. This bonding strategy paves the way for the applications of aluminosilicate glass.