常壓電漿輔助之陽極接合技術開發與應用
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2013
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雖然傳統陽極接合(anodic bonding)技術與其他接合技術相比，具有無介質、氣密性接合與製程簡易等優勢，也已廣泛運用於微機電系統(micro-electro-mechanical system, MEMS)之封裝，但卻因為加溫機制需從底部全面性加溫，除了升溫與降溫的耗時外，亦容易在升、降溫時，讓晶片受到熱效應的影響，使接合晶片上之微結構造成破壞。因此，本研究開發出創新性常壓電漿陽極接合(atmospheric pressure plasma anodic bonding, APPAB)之技術，利用電漿具有局部快速升溫與快速降溫的特性，可以大幅降低製程時間以提高效率外，還可減少試片受到熱效應的影響。另外，APPAB技術是利用常壓電漿系統的噴頭作為上電極，而此噴頭可架於具z軸移動功能之載架，且可將接合試片放置於x-y移動平台上，故在進行接合試驗時，可以自由調整上電極高度與移動接合試片，以達到局部性接合與區域性圖案化接合之目的，增加APPAB技術之應用性與彈性度。
本研究進行borofloat玻璃試片與矽晶片之接合試驗，尋求最佳接合參數，其試片之面積尺寸皆為2 cm × 2 cm。經實驗結果顯示，最佳APPAB接合參數為N2製程氣體、3 mm接合間距與2 kV接合電壓，其中試片在進行接合時，可局部性使試片於一分鐘內升溫至約420度，更可在一分鐘內使試片降至室溫約27度，升降溫速率約為62度每秒。本研究也利用最佳參數進行四吋晶片接合試驗，分別以固定式APPAB、移動式APPAB與傳統固定單點電極式陽極接合三種不同方式，來進行接合時間與接合強度之比較，其中移動式APPAB僅需14分7 秒即可將試片完全接合，且平均接合力可達37.64 MPa，與傳統式陽極接合相比，接合時間不僅快了約11倍，其平均接合力也大了1.7倍左右。此外，移動式APPAB在進行陽極接合試驗時，其電流值大約都能維持在0.8 mA左右，不會像固定式APPAB與單點電極式陽極接合之電流值，會隨著接合時間增加而遞減趨近於零，故移動式APPAB的接合品質也會比另外兩種方式來得優良。
本研究除了開發常壓電漿陽極接合技術外，為了提升本技術之應用性，除了玻璃-矽晶片之接合，還進行玻璃與玻璃鍍鋁基板、玻璃與矽鍍鎳基板及玻璃與陽極氧化鋁(anodic alumina oxide, AAO)鍍鋁基板之接合。除此之外，還利用APPAB技術結合陽極氧化鋁與熱電材料，以電化學沉積的方式，分別將p-type Sb2Te3與n-type Bi2Te3之熱電材料，沉積於AAO孔洞中，其沉積速率分別為3.5 um/hr與11 um/hr。本研究所製作之奈米熱電結構(nano structure)，將可應用於微型熱電致冷晶片(micro thermoelectric cooler, uTEC)之開發，提升相關熱電元件的性能。
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.
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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常壓電漿, 陽極接合, 熱電材料, 電化學沉積技術, 陽極氧化鋁, 奈米結構, 微熱電致冷晶片, atmospheric pressure plasma, anodic bonding, thermoelectric materials, anodic alumina oxide, micro thermoelectric cooler