隨著IC 的線寬不斷縮小並接近至極限時，3D IC 的技術發展能使 系統之效能及功能提昇，其概念是利用垂直晶片疊覆(chip stacking) 的方式將晶片構裝，其中，W2W 封裝方式效率高而成為未來發展的 主流。另外，在Thin-GaN LED 方面，W2W鍵合技術也因為發光面 積大、垂直式電流導通結構以及較均勻電流分散等特性，將是未來主 要發展的趨勢。W2W bonding 在金屬接合技術有兩個種類：(1) 固態 金屬與液態金屬鍵結、(2) 固態金屬與固態金屬鍵結。其中，固態/ 固態金屬鍵合是未來發展的重要趨勢，原因在於低溫晶圓鍵合技術可 以有效減少金屬界面層交互擴散的行為，進而避免高溫鍵合界面中介 金屬化合物形成，避免造成脆性的界面，而避免嚴重的交互擴散現象 所造成元件特性的破壞。除了上述的狀況，低溫晶圓鍵合亦會降低不 同晶圓材料間鍵合時，因熱膨脹係數差異所造成的熱應力的問題，因 此，發展低溫固態鍵合是重要的議題。 透過固態/固態金屬鍵結中原子擴散研究：平行於擴散軸施加壓應 力對於固態金屬間交互擴散中的整體自由能會增加，進一步導致原子 擴散所要跨越的能障降低的概念，並且在施加壓應力後對於兩種不同 優選方向電鍍銅層可以影響銅鈀交互擴散能障。本研究針對這些議題 設計實驗並以Boltzmann 分布中原子能跨越能障進行擴散的機率概 念，逐步探討在施加壓壓力效應下主導在銅(111)與銅(220)晶格優選 方向系統裡有明顯擴散行為差異以及關鍵因素。;In recent years, three-dimensional integrated circuit (3D IC) has been agreed as the next generation semiconductor technology with the advantages of small form factor, high-performance, low power consumption, and high density integration. In the 3 type bonding technology: chip-to-chip, chip-to-wafer, and wafer-to-wafer., wafer-to-wafer technology can be applied for homogeneous integration of high yielding devices and plays important role in productive efficiency of 3D IC. However, wafer-to-wafer bonding technology also has the advantages in Thin-GaN LED: (1) uniform current spreading and (2) high emitting area. Therefore, wafer-to-wafer technology will be important technology in the future. In wafer-to-wafer technology, solid/solid metal bonding has the property that bonding can be finished at low temperature (150~250℃). It will be important for future development: (1) Prevent the formation of intermediary metal compounds (IMC) at bonding interface, (2) Avoid the residual stress which produced by CTE mismatch in high temperature process. Compare with Cu-Cu direct bonding, we find that Cu-Pd-Cu bonding can be finished at lower bonding temperature. Importantly, external stress can reduce the finished bonding temperature, which be attributed to reduced energy barrier in solid state interdiffusion. Therefore, base on the concepts of successful atom-vacancy diffusion’s probability in Boltzmann distribution, the important factor in the difference between Cu(111)-Pd and Cu(200)-Pd with external stress will be discussed.
