Effects of Electromigration on Microstructural Evolution and Mechanical Properties of Preferential Growth Intermetallic Compound Interconnects for 3D Packaging
Effects of Electromigration on Microstructural Evolution and Mechanical Properties of Preferential Growth Intermetallic Compound Interconnects for 3D Packaging
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DOI：
10.1109/ectc.2019.00274
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发表时间：
2019-05
期刊：
影响因子：
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通讯作者：
Mingliang L. Huang;L. Zou
中科院分区：
文献类型：
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作者：
Mingliang L. Huang;L. Zou
采用电流驱动键合（CDB）方法在（111）Cu单晶衬底上制备了全优先生长金属间化合物（IMC）互连，并对（111）Cu/IMC(30µm Cu6Sn5)/Cu互连中全优先生长Cu6Sn5晶粒的形貌、取向、电迁移电阻和力学性能进行了研究。CDB方法成功地控制了晶体取向，保持了Cu6Sn5晶粒在（111）Cu单晶衬底上的优先生长。棱柱型Cu6Sn5晶粒具有织构特征，且Cu6Sn5的连续优先外延生长形成了与电流流动方向平行的完整IMC互连。全优先生长IMC互连的制备为统一IMC互连的取向提供了一种方法，有效地消除了晶粒取向的随机分布，从而消除了互连的各向异性。全（111）Cu/Cu6Sn5/Cu IMC互连在高温时效和大电流应力作用下仍具有良好的耐电迁移性能和机械可靠性。时效和150℃、180℃电流应力（2.0×104 A/cm2）作用500 h后，均未出现明显损伤。在150℃时效500 h和150℃电流应力（2.0×104 A/cm2）作用500 h后，完全优先生长IMC互连体的平均抗拉强度保持不变，分别为111.1 MPa和108.1 MPa，与焊接状态（118.8 MPa）相近。本研究可望为全优先生长高强度IMC互连在3D集成电路封装中的应用提供理论支持和指导。
The full preferential growth intermetallic compound (IMC) interconnects are fabricated on a (111) Cu single crystal substrate by the method named current driven bonding (CDB), and the morphology, orientation, electromigration resistance and mechanical properties of the full preferential growth Cu6Sn5 grains in the (111) Cu/IMC (30 µm Cu6Sn5)/Cu interconnects are investigated. The CDB method successfully controls the crystal orientation and maintains the preferential growth of Cu6Sn5 grains on (111) Cu single crystal substrate. The prism-type Cu6Sn5 grains show a texture feature and the continuous preferential epitaxial growth of Cu6Sn5 form the full IMC interconnect with Cu6Sn5 directions paralleling to the current flowing direction. The fabrication of full preferential growth IMC interconnects provides an approach to unify the orientations of the IMC interconnects, which effectively eliminates the random distribution of grain orientations and thus the anisotropy of interconnects. The full (111) Cu/Cu6Sn5/Cu IMC interconnects exhibite an excellent electromigration resistance and high mechanical reliability even after having experienced high temperature aging and high current stressing. There is no obvious damage after aging and current stressing (2.0×104 A/cm2) at 150 oC and 180 oC even for 500 h. The average tensile strength of full preferential growth IMC interconnects remaines unchanged, i.e., 111.1 MPa and 108.1 MPa, even after aging at 150 oC for 500 h and current stressing (2.0×104 A/cm2) at 150 oC for 500 h, respectively, which are similar to that of the as-soldered state (118.8 MPa). This work is expected to provide theory support and guidance for the application of full preferential growth and high strength IMC interconnects in 3D IC packaging.