Ultrafast laser packaging of glass and silicon: Microsturcture and mechanical property

Borosilicate glass and monocrystalline silicon were successfully connected using a novel joining process, viz., ultrafast laser packaging. The orthogonal test design optimization with three factors and levels including single pulse energy, scanning speed, and scanning path was conducted. The resultant packaged regions were continuous and uniform. The maximum tensile strength reached 12 MPa. The interfacial microstructure and fracture behavior were carefully characterized using SEM, EDS, XRD and TEM. The results showed that four distinct regions were observed at the packaged zone, where recrystallized SiO₂ and a new phase (SiB₆) were generated. This phase transformation was mainly ascribed to the melting, mixing, and diffusion of the materials during the ultrafast laser packaging process. In addition, an interfacial brittle failure with a strong materials intermixing was obtained. This novel packaging process is very promising in the fabrication of the microelectromechanical system (MEMS) devices.