13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- Silicon Glass 500 nm (a) 50 nm aluminum film (b) 95 nm aluminum film Figure 7. Dendritic nanostructures of specimens at 350°C and 400 V Figure 8 illustrates the EDX analysis position and element analysis result of the nano dendritic structures under STEM mode. The electron beam scanning path is marked with a black thick line across three trunks of the dendritic structures, as shown in Figure 8(a). Element analysis indicates that the dendritic nanostructures are aluminum enriched, as shown in Figure 8(b). STEM/EDX microanalysis provides enough evidence of diffusion of aluminum into the Pyrex glass during anodic bonding. Examined by EDX, the trunks exhibit lesser counts of silicon and oxygen while the aluminum counts are conspicuously increased. 0 50 100 150 200 0 20 40 60 80 100 120 140 160 180 200 Counts Position (nm) Al (a) Scanning position (b) Element counting Figure 8. Scanning position and element counting for EDX analysis 3.2. Bonding strength The mean bonding tensile strength are shown in Figure 9. Bonding tensile strength, which is averaged from the results of five or more specimens. The measured bonding strength values exhibit a rather large variance around a mean value. This can be attributed to several aspects, such as the misalignment of specimens, the characteristics of bonding behavior [21], the micro defects due to residual stress, and etc. All the specimens pulled apart were also examined with the optical microscope and scanning electron microscope (SEM), and some parts of the aluminum film and the Pyrex glass were residual on the opposite side.
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