| Summary: | 碩士 === 國立臺灣師範大學 === 機電科技學系 === 101 === Although the conventional anodic bonding technique, compared with another bonding techniques, has been widely used in micro-electro-mechanical system (MEMS) package, for the benefits of non-intermediate, tight binding, and simple process. However, its heating mechanism is always conducted completely from the bottom of the specimens, which not only spend lots of time to heat up and cool down, but also make microstructures on the bonded chips easily damaged by thermal effect at heating and cooling periods. Hence, this study developed a creative technique, which is called as atmospheric pressure plasma anodic bonding (APPAB). Plasma has an advantage of locally rapid heating and cooling, so this technique does not only reduce the process time and significantly enhance the bonding efficiency, but also decreases the thermal effect of bonded specimens. Moreover, the jet head of an atmospheric plasma system is used as the upper electrode of APPAB, and such a jet head is fixed on a frame, which is movable along z-axis; the bonded specimens are also placed on a platform, which can be moved along x-y axis. When the bonding tests are carried out, the height of upper electrode and the position of bonded specimens can be easily adjusted, then the localized bonding and regional pattern definition can be achieved and increase the applicability and flexibility of APPAB.
In order to search optimum bonding parameters, this study used borofloat glasses and silicon with the size of 2 cm × 2 cm to conduct bonding experiments. According to the experimental results, the optimum parameters have been obtained under process gas of N2, bonding distance of 3 mm, and bonding voltage of 2 kV. During conducting the APPAB experiments, the specimens can be heated to about 420 degrees Celsius, and cooled to about 27 degrees Celsius in a minute, so the rate of heating and cooling is about 62 degrees Celsius/s. This study also used the optimum parameters to execute the bonding tests of 4-inch specimens, for the purpose of comparing bonding time and bonding stress under fixed-APPAB, mobile-APPAB, and the conventional anodic bonding of single-point electrode. Among three methods, mobile-APPAB only spends 14 min and 7 s to complete the bonding of 4-inch specimen, and its average bonding stress is 37.64 Mpa. Its bonding time is approximately 11 times faster and bonding stress is 1.7 times stronger than those of conventional anodic bonding. In addition, the bonding current of mobile-APPAB can be kept at about 0.8 mA, but the currents of fixed-APPAB and conventional anodic bonding will decrease and approach to zero with bonding time. Consequently, the bonding quality of mobile-APPAB will be better than other two bonding techniques.
Except developing a creative APPAB technique for glass-Si bonding, the study also tests the other material combinations of glass-Al/glass, glass-Ni/Si, and glass-Al/AAO for enhancing the applicability of APPAB. Moreover, the thermoelectric nanostructures have been realized using a glass-Al/AAO substrate as a template, and electrochemically deposits p-type Sb2Te3 and n-type Bi2Te3 into the hole of AAO, and their deposition rates are 3.5 um/hr and 11 um/hr, respectively. These thermoelectric nanostructures will be used to fabricate uTEC in the future, and promote the performance of thermoelectric devices.
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