可變電壓波形應用於陽極接合速度與品質之研究

Abstract

陽極接合技術常被應用於微機電元件的組裝，是目前微機電製程中相當倚重的一種接合技術，其主要藉由離子鍵結的方式來達到接合的目的，故兩接合表面平整度要求非常高，屬於無介質的接合方式。在接合過程中，輸出電壓大小、溫度高低、電極形式等，皆是影響接合率和品質的重要因素。在不同的電壓輸出形式上，亦可造成不同的接合效果，原因是當通入一般常用定電壓輸出時，其所產生的接合電流瞬間達到最高峰，此狀態亦將隨著時間的增加而產生遞減現象。若選用可變電壓波形輸出時，將可促使瞬間最大接合電流，重覆維持在一高峰值，進而大幅提升接合率與接合品質。實驗結果證實，利用輻射狀電極在方波可變電壓波形之平均電壓250 V、週期時間8 s、溫度400 °C、接合時間200秒，進行四吋全片接合時，接合良率可達99.2 左右%。 其次本研究也研發一種新型的圓錐截頭體電極，搭配可變電壓波形輸出形式，除了可使接合電流維持在一高峰值，縮短其所需接合時間外，也可在較低電壓輸出的條件下，達到快速接合，且擁有與定電壓輸出形式相同的接合品質。實驗結果證實，利用圓錐截頭體電極搭配定電壓輸出，設定平均電壓800 V、溫度400 °C條件下，進行四吋全片接合時，接合時間約15秒，且接合良率可達99.89 %左右。利用圓錐形電極搭配方波可變電壓波形輸出，設定平均電壓250 V、週期時間8 s、溫度400 °C條件下，進行四吋全片接合時，接合時間約15秒，接合良率可達72.93 %。利用方波可變電壓與定電壓波形，搭配圓錐截頭體電極進行實驗時，因為受硬體設備之限制，導致實驗過程中，輸出電壓均無法到達設定值，但其實驗結果仍達到預期的目標。Anodic bonding technique is important and is often used in package of MEMS components. It uses ionic bond to obtain bonding results. Surface level of silicon and glass need to be very serious, and the technique belong to non-media bonding. There are important factors of bonding ratio and quality in bonding process, such as applied voltage, temperature, and type of electrode etc. In different forms of applied voltage, it causes different bonding results. The reason is described as follow: the maximum of bonding current by using constant voltage waveform would be decayed when the bonding time is increasing, but it will be kept at a high value by using variable voltage waveform and to improve bonding ratio and quality widely. The research improves that using radiate-line electrode with square voltage waveform to bonding 4 inch wafer, bonding ratio can reach 99.2% when the average voltage is 250 V, periodis 8 sec, temperature is 400 ºC, and bonding time is 200 sec. In this research, we develop a novel conical frustum electrode to co-operate variable voltage waveform for anodic bonding. It not only can keep bonding current at a high value to decrease bonding time, but also can have the same bonding quality with the results of applied constant voltage. The research improves that using novel electrode with constant voltage waveform to bonding 4 inch wafer, bonding ratio can reach 99.98% when the average voltage is 800 V, temperature is 400 ºC, and bonding time is 15 sec. Using the novel electrode with square voltage waveform to bonding 4 inch wafer, bonding ratio only can reach 72.93% when the average voltage is 250 V, period is 8 sec, temperature is 400 ºC, and bonding time is 15 sec. The efficiency of bonding system is limited when using square or constant voltage waveforms to co-operate the conical frustum electrode. Although it causes output voltage can not reach the setting value in bonding process, the research still can achieve the expecting purpose.