矽-旋轉式塗佈玻璃-矽的陽極鍵結技術在微機電系統上的應用

Abstract

以濺鍍沈積的硼矽玻璃薄膜為中間層的矽-矽陽極鍵結技術，在微機電系統上的應用是相當具有潛力的製程。其優點在於製程相較於Pyrex玻璃-矽的陽極技術更為可靠性與適應性。然而此一硼玻璃易在薄膜表面形成硼酸，以導致鍵結不易或是需在更高的操作溫度下才能得到較佳的鍵結效果；同時，耗時而且較低的濺鍍薄膜沈積速率與濺鍍薄膜組成不易控制都是製程上的問題。 在本篇論文嘗試以旋轉式塗佈法來製備適膈於矽-矽陽極鍵結枝術的玻璃薄膜。在製程中液態的sol溶液是以旋轉塗佈的方式來應用。溶液是混合有機矽化物而成，其中包含：TEOS(Tetraethy1 orthosilicate)、MTEOS(Methytriethy1 orthosilicate)與鈉鹽都溶於乙醇溶劑中。經由小心的熱處理後，薄膜具有含量約5%的氧化鈉以及每次旋轉塗佈可獲得約100~300nm薄膜厚度。在本篇論文中成功的在350℃的低溫下完成矽-矽陽極鍵結的製程；同時，在400℃160V下可以得在最佳的鍵結強度5.86MPa。

Silicon to silicon anodic bonding by use of sputter deposited borosilicate film is a promising mounting method for microelectromechanical systems (MEMS).The advantages of the silicon to silicon anodic bonding were like its reliability and flexibility in contrast to the wide use of anodic bonding with Pyrex glass substrates. Boron glass has a strong tendency to form born acid. on the surface that makes bonding impossible or with a high process temperature for safe bonding. Also, the low deposition rates sputtering of glass layers is time consuming and difficult to control the composition of the sputtered glass layers ect. In this thesis, we present the preparation of glass layers that were suitable for the anodic bonding of two silicon substrates using spin on glass. In this process a liquid sol solution is used within a spin coating process. The solution is a mixture based on organic silicon containing compounds, like TEOS (Tetremethy1 orthodilicate), and a sodium salt all dissolved in ethanol. After a careful thermal treatment, silica film containing about 5% wt. Na2O can be obtained with a thickness in the range from 100nm to 300nm is one deposition step. Anodic bonding of two silicon substrates is possible with films at bonding temperature 350℃ and the optimized bonding strength is 5.86 MPa for applied voltage 160V at 400℃．