三維積體電路技術之光裂解高分子於暫時性接合與鎳錫導線暫態液相接合研究

Abstract

本碩士論文研究包含兩個在三維積體電路的接合技術的主題，分別應用於暫時性接合與永久性接合的不同方式。由於超薄化晶圓的多功能性，垂直堆疊時搭配此種技術的需求也日益增加，因此暫時性接合及後續的剝離技術逐漸地被重視，相關的研究也推陳出新。在前人的研究中，我們發現其接合後的總厚度皆大於20微米、整體的實驗過程有較高的熱成本且後續的剝離方法通常需花費較多的時間。這些種種的因素導致三維積體電路技術在暫時性接合領域的開發日益趨緩。為了有效地提升此項技術的應用，我們提出了一種新的結構。在此結構中，我們加入了一層次微米級且可被光蝕刻的高分子材料當作剝離層，並與另一種當作黏著層的高分子材料做暫時性接合，可在250度的接合溫度下得到完美的結果。除此之外，我們所提出的結構更有以下幾種優點：接合後的總厚度小於10微米、兩片試片的剝離時間小於20秒、具有良好的機械強度及此結構能應用於現今半導體產業。 我們在永久性接合的技術中提出了利用暫態液相接合，成功地在低溫將鎳跟錫形成金屬連接並且突破了現階段最小厚度5微米銅錫接合的物理極限。從材料分析的結果中，我們得到一個均質的薄膜接合結果，且其所形成的介金屬化合物具有可承受高溫的特性。更進一步地研究發現，鎳錫接合具有不錯的接合強度，且在後續的電性量測中得到近似於塊材的接觸電阻。此金屬接合結構也成功地通過濕度測試及高溫衝擊測試等可靠度實驗。 綜合以上的描述，在本研究中所提出的兩項技術皆改善了接合的品質，並且具備實際的應用於三維積體電路的潛力。

In this thesis, two topics have been proposed in development of temporary bonding and permanent bonding for bonding technology in 3D integration. Due to the demand of ultra-thin device wafer for multi-functional applications in vertical stacking, research topics about temporary bonding and de-bonding process become important. In previous works, larger than 20-µm thickness, high thermal budget, and inefficient de-bonding methods lead to slow evolution of 3D integration. In order to improve the quality of temporary bonding, a photolysis polymer with submicron thickness is investigated. The novel scheme which is combined release layer with adhesive layer realize in perfect results at 250 °C. In addition, the results of bonded wafers show minimum size (< 10-µm), ultra-fast de-bonding time (< 20 sec), excellent mechanical strength, and compatible to current semiconductor industry. Next, a submicron of Ni/Sn transient liquid phase bonding at 250 °C is demonstrated to overcome current 5-µm Cu/Sn physical limitation. The material analysis indicates homogeneous film, high-temperature stable intermetallic compounds, and good mechanical properties in the bonded structure. Moreover, the Ni/Sn interconnects bonded at low temperature all exhibits great electrical characteristics and reliable performance after 1000 cycles thermal cycling test and 264 hr humidity test. To sum up, the research results not only provide realistic options to dramatically ameliorate bonding technology, but also demonstrate the feasibility in 3D integration applications.