Abstract
晶圓鍵結對於製作矽在絕緣層上的結構方面是一個頗具吸引力的技術。為應用這個方法於矽在絕緣層上的結構，獲致無孔洞的界面是非常重要的。因之，兩個充分平坦、平滑、無塵粒、且高親水性的表面，對於在室溫且無外力的條件下之矽的晶圓鍵結是需要的。實驗步驟，首先晶圓需經過特定的濕式化學清潔方法清洗之後，以便得到一個表面之雜質密度、塵粒密度、粗糙度、及親水性為晶圓鍵結所容許範圍內的晶圓表面。之後，這些剛完成濕式化學清潔的晶圓，在室溫及無塵室的環境之下以面對面的方式執行前鍵結，以達成無孔洞的整片4 吋晶圓之前鍵結。這被前鍵結的晶圓對被置入一個在氮氣氛下400 ℃之爐管停留約40分鐘，以便排除界面間過量的水，之後在1050℃停留約兩個小時，以便加強其鍵結強度，以達成無孔洞的整片4 吋晶圓之鍵結。至於絕緣層的厚度取決於實驗者的用途，可有不同的調整。本文係探討一些參數（親水性、粗糙度、微粒密度、及被陷住的氣體）對晶圓鍵結品質的影響及研究鍵結界面的特性。矽及二氧化矽在濕性化學清洗後的表面的化學狀態可由傅利葉轉換紅外線光譜偵測之，包括穿透式及全反射式兩種。在剛清洗後之晶圓表面的微粗糙度可藉由原子力顯微鏡來鑑定之。而在不同溶液清洗後之表面微塵粒子的分布與密度由表面掃描顯微鏡來研究。在退火後的鍵結界面其孔洞的呈現可利用穿透式紅外線影像系統來進行。區域性的鍵結結構藉由橫截面的穿透式電子顯微鏡來鑑定其特性。Wafer bonding is an attractive technique for silicon-on-insulator (SOI) structure. To apply this method to SOIstructure, it is very important to obtain void-free interface.Two sufficiently flat, smooth, particle-free, and highhydrophilic surfaces are contacted for silicon wafer bonding atroom temperature without using any external force. Then thebonded wafers are loaded into a furance at temperature 1050 ℃in a nitrogen atmo- sphere and stayed them for 1.5-2 hours toprompt the bonding strengh. Basically, The SOI wafer isfabricated by four basic process steps. The first step is toachieve a sufficiently flat, smooth, particle-free, andhydrophilic surface by a number of wet chemical cleaningprocesses. The second step is the mating of two wafers togetherat room temperature without using any external force. The thirdstep consists of the annealing over 800 ℃ (usually 1000-1100℃ used) to increase the bond strengh. The four step is to thindown one of the two wafers to an appro- priate thickness bygrinding, lapping, polishing, and etching. Our experimentsfocus on the first three steps. The local bonded structure wascharacterized by cross-sectional transmission electron micro-scopy (XTEM). Surface chemical conditions of silicon andsilicon dioxide after wet cleaning were investigated by Fouriertranformation in- frared ray (FT-IR) spectroscopy, includingtrans- mission and attenuated total reflection methods. Surfacemicro-roughness of silicon and silicon dioxide after wetcleaning was observed by atomic force microscopy (AFM). Thedistribution of dust particles on wafer surfaces after cleanedby the solutions was studied by surface scan microscopy (SSM).The presence of voids at bonded interfaces prepared afterhydrophilizing surface treatment have previously beendemonstrated by using a transmission infrared ray image system.