三維積體電路微銲點中Ni3Sn4之機械行為

Abstract

本實驗使用微米柱壓縮測試與奈米壓痕試驗兩種方法探討不同晶粒取向Ni3Sn4介金屬之機械行為。在封裝逐漸走向晶片垂直堆疊以及銲點尺度急劇縮小的趨勢下，研究Ni3Sn4之機械行為便顯得更加重要與迫切。本實驗發現，在經過高溫長時間時效後，Ni3Sn4退火雙晶大量生成，本研究亦鑑定出Ni3Sn4退火雙晶之雙晶要素。由實驗之應力應變曲線可知，Ni3Sn4表現出脆性之機械行為，且經過壓縮測試後，Ni3Sn4微米柱沿著某些平面破裂。然而，不同於以往對介金屬化合物相當脆的認知，在某些特定的晶粒取向中，Ni3Sn4微米柱在完整的壓縮測試後並未發生破壞，反而展現塑性形變的行為，並且擁有良好的應變量。透過穿透式電子顯微鏡的分析發現，Burgers vector [0 1 0]之差排的滑移為Ni3Sn4產生塑性形變的主要機制，同時，Ni3Sn4之滑移系統亦可由穿透式電子顯微鏡分析鑑定，其滑移系統為(1 0 0)[0 1 0]。另一方面，由Schmid factor之計算得知，晶粒取向接近(19 7 1)與(('17' ) ̅ 6 1)時較容易啟動(1 0 0)[0 1 0]滑移系統並表現出較佳的機械性質。本研究亦量測出許多極具價值之機械性質，諸如：從微米柱壓縮測試所得之楊氏係數、降伏強度、破壞強度、破壞時之應變與降伏時之應變，以及由奈米壓痕測試所得之楊氏係數與硬度，而這些數據對於了解三維積體電路中微銲點之機械可靠度極具貢獻。另外，針對本實驗所使用之兩種量測方式的比較、優缺點及使用定位也有詳細的探討。

The micromechanical behaviors of single crystalline intermetallic compound Ni3Sn4 with different crystallographic orientations are investigated by using micropillar compression and nanoindentation. Knowledge of the mechanical behaviors of Ni3Sn4 is important because of its application in micro joints for chip-stacking applications. During high temperature aging, annealing twins easily form in Ni3Sn4 and the twin elements are identified. The stress-strain curves from micropillar compression show that Ni3Sn4 exhibits a brittle fracture behavior. However, pillars with certain orientations do not undergo catastrophic fracture, but are able to deform plastically. Transmission electron microscopy analysis shows that dislocations with Burgers vector [0 1 0] are involved in the plastic deformation and the slip system of Ni3Sn4 is (1 0 0)[0 1 0]. The reasons why Ni3Sn4 slips on (1 0 0) plane along [0 1 0] direction is discussed in terms of its crystal structure and bonding strength. In addition, grain orientations close to (19 7 1) and (('17' ) ̅ 6 1) are more likely to activate the slip system (1 0 0)[0 1 0] and exhibit better mechanical properties since they have greater Schmid factors. Young’s modulus, yield strength, fracture strength, strain at fracture, and strain at yield along several orientations are reported. Advantages of each of these two methods and comparisons between these two methods are discussed.