Mechanical strength of anchor–microbeam combined structure fabricated by silicon-on-glass process

To investigate the mechanical strength of the anchor-microbeam combined structure, two series of devices (bonding quality testing devices and torsional strength testing devices) are designed and fabricated by the silicon-on-glass process. A novel array-shaped anchor scheme is presented, which has been compared with the conventional single anchor. The experimental results have shown that the bonding quality of the anchor degenerated severely when the bonding area became very small (<;400 μm²). The testing results of bonding quality testing devices demonstrated that the presented array-shaped anchor design helped to improve the anodic bonding yield. According to the bending fracture test of the torsional strength testing devices, the array-shaped anchor design had an almost equal torsional strength compared with the single anchor with the same occupied area. Moreover, the torsional strength of the array-shaped anchor was even greater when the bonding area was the same. In the fracture test, the fracture would happen in the anchor since the structure size was small. When the structure was larger, the fracture happened in the cantilever beam, rather than the anchor.