Please wait a minute...
金属学报  2018, Vol. 54 Issue (7): 1077-1086    DOI: 10.11900/0412.1961.2017.00426
  本期目录 | 过刊浏览 |
倒装芯片无铅凸点β-Sn晶粒取向与电迁移交互作用
黄明亮(), 孙洪羽
大连理工大学材料科学与工程学院 先进连接技术辽宁省重点实验室 大连 116024
Interaction Between β-Sn Grain Orientation and Electromigration Behavior in Flip-Chip Lead-Free Solder Bumps
Mingliang HUANG(), Hongyu SUN
Key Laboratory of Liaoning Advanced Welding and Joining Technology, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China
全文: PDF(8515 KB)   HTML
摘要: 

采用原位电迁移实验研究了在150 ℃、1.0×104 A/cm2条件下倒装芯片Ni/Sn-3.0Ag-0.5Cu/Ni-P无铅凸点中β-Sn晶粒取向对金属间化合物(IMC)的聚集析出机制、阴极Ni芯片侧(UBM)溶解行为、电迁移失效机制以及电迁移驱动下β-Sn晶粒的旋转滑移机制的影响。原位观察发现,电迁移过程中(Ni, Cu)3Sn4类型IMC在凸点中仅沿着β-Sn晶粒的c轴方向析出,且倾向于在θ角(β-Sn晶粒的c轴与电子流动方向之间的夹角)较小的晶粒内析出;同时,阳极附近观察到β-Sn挤出现象,即凸点出现应力松弛。建立了阴极Ni UBM溶解量与β-Sn晶粒取向的关系模型:β-Sn晶粒取向决定阴极Ni UBM的溶解量,即当θ角很小时,Ni UBM会出现明显溶解;当θ角增大时,Ni UBM的溶解受到抑制,该模型与实验值基本吻合。电迁移导致β-Sn晶粒发生旋转滑移,认为是由于不同取向的相邻β-Sn晶粒中电迁移导致的空位通量不同,从而导致阳极晶界处于空位的过饱和,阴极晶界处于空位的未饱和状态,并促使空位沿着晶界出入于自由表面,最终在垂直方向上会产生空位梯度,由沿晶界的空位梯度对应的应力梯度产生的力矩使β-Sn晶粒发生旋转滑移。

关键词 电迁移β-Sn;各向异性阴极溶解IMC析出晶粒旋转    
Abstract

With the increasing demands for miniaturization, the electromigration (EM)-induced failure by diffusion anisotropy in β-Sn is expected to be more serious than that induced by local current crowding effect, especially with the downsizing of solder bumps. In this work, the effects of Sn grain orientation on intermetallic compound (IMC) precipitation, dissolution of Ni under bump metallurgy (UBM) at the cathode, EM failure mechanism as well as the EM-induced β-Sn grain rotation in Ni/Sn-3.0Ag-0.5Cu/Ni-P flip-chip interconnects undergoing solid-solid EM under a current density of 1.0×104 A/cm2 at 150 ℃ were in situ studied. (Ni, Cu)3Sn4-type IMCs precipitated in these β-Sn grains with a small angle θ (between the c-axis of Sn grain and electron flow direction), i.e., along the c-axis of β-Sn grains. Stress relaxation, squeezing β-Sn whiskers near the anode, was also observed during EM. A mathematical model on the relationship between the dissolution of Ni UBM and β-Sn grain orientation was proposed: when the c-axis of β-Sn grain is parallel to the electron flow direction, excessive dissolution of the cathode Ni UBM occurred due to the large diffusivity of Ni along the c-axis; when the c-axis of β-Sn grain is perpendicular to the electron flow direction, no evident dissolution of cathode Ni UBM occurred. The proposed model agreed well with the experimental results. EM-induced β-Sn grain rotation was attributed to the different vacancy fluxes caused by EM between adjacent grains of various grain orientation, when vacancies reached supersaturation and undersaturation at the interfaces of the anode and the cathode, respectively. Vacancy fluxes went through free surface along the interface, resulting in a normal vacancy concentration gradient. Accordingly, stress gradient produces a torque to rotate the β-Sn grain.

Key wordselectromigration    β-Sn;    anisotropy    cathode dissolution    IMC precipitation    grain rotation
收稿日期: 2017-10-13      出版日期: 2018-03-27
ZTFLH:  TN405  
基金资助:国家自然科学基金项目Nos.51475072、51511140289和51671046,中央高校基本科研业务费项目No.DUT17ZD202
作者简介:

作者简介 黄明亮,男,1970年生,教授,博士

引用本文:

黄明亮, 孙洪羽. 倒装芯片无铅凸点β-Sn晶粒取向与电迁移交互作用[J]. 金属学报, 2018, 54(7): 1077-1086.
Mingliang HUANG, Hongyu SUN. Interaction Between β-Sn Grain Orientation and Electromigration Behavior in Flip-Chip Lead-Free Solder Bumps. Acta Metall, 2018, 54(7): 1077-1086.

链接本文:

http://www.ams.org.cn/CN/10.11900/0412.1961.2017.00426      或      http://www.ams.org.cn/CN/Y2018/V54/I7/1077

图1  倒装芯片Ni/Sn-3.0Ag-0.5Cu/ENEPIG无铅凸点结构示意图
图2  倒装芯片Ni/Sn-3.0Ag-0.5Cu/Ni-P无铅凸点回流后初始微观形貌
图3  1号倒装芯片Ni/Sn-3.0Ag-0.5Cu/Ni-P无铅凸点在150 ℃、1.0×104 A/cm2条件下原位电迁移不同时间后的微观形貌及沿轴向的EBSD取向分布
图4  2号倒装芯片Ni/Sn-3.0Ag-0.5Cu/Ni-P无铅凸点在150 ℃、1.0×104 A/cm2条件下原位电迁移不同时间后的微观形貌及沿RD方向的EBSD取向分布
图5  3号倒装芯片Ni/Sn-3.0Ag-0.5Cu/Ni-P无铅凸点在150 ℃、1.0×104 A/cm2条件下原位电迁移不同时间后的微观形貌及沿RD方向的EBSD取向分布
图6  4号倒装芯片Ni/Sn-3.0Ag-0.5Cu/Ni-P无铅凸点在150 ℃、1.0×104 A/cm2条件下原位电迁移不同时间后的微观形貌及沿RD方向的EBSD取向分布
图7  5号倒装芯片Ni/Sn-3.0Ag-0.5Cu/Ni-P无铅凸点在150 ℃、1.0×104 A/cm2条件下原位电迁移不同时间后的微观形貌及沿RD方向的EBSD取向分布
  
Axis ρ γ E D (150 ℃) / (cm2s-1) DT (150 ℃)
μΩcm 10-6-1 GPa Ag Cu Ni m2s-1
a 13.25 15.45 22.9 5.60×10-11 1.99×10-7 3.85×10-9 8.70×10-13
c 20.27 30.50 68.9 3.13×10-9 8.57×10-6 1.17×10-4 4.71×10-13
表1  β-Sn的各向异性参数[8,9,10]
Parameter Valne Unit
Z*[23] 3.5 -
CNi 1.858×1024 atomsm-3
T 423 K
i 1.0×108 Am-2
ρSn 1.18×10-7 Ωm
Ω 6.6×10-6 m3mol-1
l 1.0 μm
δ 0.0125 μm
表2  计算用材料参数
图9  阴极Ni UBM消耗和q角的函数关系
图10  倒装芯片Sn-3.0Ag-0.5Cu无铅凸点中电迁移致晶粒旋转示意图
[1] Jung Y, Yu J.Electromigration induced kirkendall void growth in Sn-3.5Ag/Cu solder joints[J]. J. Appl. Phys., 2014, 115: 083708
doi: 10.1063/1.4867115
[2] Huang M L, Zhou S M, Chen L D.Electromigration-induced interfacial reactions in Cu/Sn/Electroless Ni-P solder interconnects[J]. J. Electron. Mater., 2012, 41: 730
doi: 10.1007/s11664-012-1952-6
[3] Chen L D, Huang M L, Zhou S M.Effect of electromigration on intermetallic compound formation in line-type Cu/Sn/Cu interconnect[J]. J. Alloys Compd., 2010, 504: 535
doi: 10.1109/ECTC.2010.5490898
[4] Chen C, Tong H M, Tu K N.Electromigration and thermomigration in Pb-free flip-chip solder joints[J]. Annu. Rev. Mater. Res., 2010, 40: 531
doi: 10.1146/annurev.matsci.38.060407.130253
[5] Huang M L, Ye S, Zhao N.Current-induced interfacial reactions in Ni/Sn-3Ag-0.5Cu/Au/Pd(P)/Ni-P flip chip interconnect[J]. J. Mater. Res., 2011, 26: 3009
doi: 10.1557/jmr.2011.373
[6] Kim K S, Huh S H, Suganuma K.Effects of intermetallic compounds on properties of Sn-Ag-Cu lead-free soldered joints[J]. J. Alloys Compd., 2003, 352: 226
doi: 10.1016/S0925-8388(02)01166-0
[7] Zhang Z J.Liquid-solid electromigration behavior and mechanism of micro interconnect [D]. Dalian: Dalian University of Technology, 2016
[8] Dyson B F, Anthony T R, Turnbull D.Interstitial diffusion of copper in tin[J]. J. Appl. Phys., 1967, 37: 3408
doi: 10.1063/1.1710127
[9] Yeh D C, Huntington H B.Extreme fast-diffusion system: Nickel in single-crystal tin[J]. Phys. Rev. Lett., 1984, 53: 1469
doi: 10.1103/PhysRevLett.53.2185
[10] Huang F H, Huntington H B.Diffusion of Sb124, Cd109, Sn113, and Zn65 in tin[J]. Phys. Rev., 1974, 9B: 1479
doi: 10.2307/3637828
[11] Lu M H, Shih D Y, Lauro P, et al.Effect of Sn grain orientation on electromigration degradation mechanism in high Sn-based Pb-free solders[J]. Appl. Phys. Lett., 2008, 92: 211909
doi: 10.1063/1.2936996
[12] Huang M L, Zhang Z J, Zhao N, et al.In situ study on reverse polarity effect in Cu/Sn-9Zn/Ni interconnect undergoing liquid-solid electromigration[J]. J. Alloys Compd., 2015, 619: 667
doi: 10.1016/j.jallcom.2014.08.263
[13] Huang M L, Zhao J F, Zhang Z J, et al.Dominant effect of high anisotropy in β-Sn grain on electromigration-induced failure mechanism in Sn3.0Ag-0.5Cu interconnect[J]. J. Alloys Compd., 2016, 678: 370
doi: 10.1016/j.jallcom.2016.04.024
[14] Harris K E, Singh V V, King A H.Grain rotation in thin films of gold[J]. Acta Mater., 1998, 46: 2623
doi: 10.1557/PROC-403-15
[15] Moldovan D, Yamakov V, Wolf D, et al.Scaling behavior of grain-rotation-induced grain growth[J]. Phys. Rev. Lett., 2002, 89: 206101
doi: 10.1103/PhysRevLett.89.206101
[16] Lloyd J R.Electromigration induced resistance decrease in Sn conductors[J]. J. Appl. Phys., 2003, 94: 6483
doi: 10.1063/1.1623632
[17] Wu A T, Gusak A M, Tu K N, et al.Electromigration-induced grain rotation in anisotropic conducting beta tin[J]. Appl. Phys. Lett., 2005, 86: 241902
doi: 10.1063/1.1941456
[18] Wu A T, Hsieh Y C.Direct observation and kinetic analysis of grain rotation in anisotropic tin under electromigration[J]. Appl. Phys. Lett., 2008, 92: 121921
doi: 10.1063/1.2901155
[19] Huntington H B, Grone A R.Current-induced marker motion in gold wires[J]. J. Phys. Chem. Solids, 1961, 20: 76
doi: 10.1016/0022-3697(61)90138-X
[20] Shi J H, Huntington H B.Electromigration of gold and silver in single crystal tin[J]. J. Phys. Chem. Solids, 1987, 48: 693
doi: 10.1016/0022-3697(87)90060-6
[21] Prakash K H, Sritharan T.Interface reaction between copper and molten tin-lead solders[J]. Acta Mater., 2001, 49: 2481
doi: 10.1016/S1359-6454(01)00146-X
[22] Liu C Y, Ke L, Chuang Y C, et al.Study of electromigration-induced Cu consumption in the flip-chip Sn/Cu solder bumps[J]. J. Appl. Phys., 2006, 100: 083702
doi: 10.1063/1.2357860
[23] Linares X, Kinney C, Lee K O, et al.The Influence of Sn orientation on intermetallic compound evolution in idealized Sn-Ag-Cu 305 interconnects: An electron backscatter diffraction study of electromigration[J]. J. Electron. Mater., 2014, 43: 43
doi: 10.1007/s11664-013-2789-3
[24] Huntington H B.Diffusion in Solids: Recent Developments [M]. New York: Academic Press, 1975: 303
[25] Huang M L, Zhang Z J, Zhao N, et al.A synchrotron radiation real-time in situ imaging study on the reverse polarity effect in Cu/Sn-9Zn/Cu interconnect during liquid-solid electromigration[J]. Scr. Mater., 2013, 68: 853
doi: 10.1016/j.scriptamat.2013.02.007
[1] 王强, 董蒙, 孙金妹, 刘铁, 苑轶. 强磁场下合金凝固过程控制及功能材料制备[J]. 金属学报, 2018, 54(5): 742-756.
[2] 李旭东, 毛萍莉, 刘晏宇, 刘正, 王志, 王峰. 高应变速率下Mg-3Zn-1Y镁合金的各向异性及变形机制[J]. 金属学报, 2018, 54(4): 557-565.
[3] 季培蓓, 周立初, 周雪峰, 方峰, 蒋建清. 冷拉拔珠光体钢丝的力学性能各向异性研究[J]. 金属学报, 2018, 54(4): 494-500.
[4] 林艳丽, 何祝斌, 初冠南, 闫永达. 利用管状试样测试各向异性材料双向应力状态力学性能的新方法[J]. 金属学报, 2017, 53(9): 1101-1109.
[5] 张志杰,黄明亮. Cu/Sn-52In/Cu微焊点液-固电迁移行为研究[J]. 金属学报, 2017, 53(5): 592-600.
[6] 张青松,朱振宇,高杰维,戴光泽,徐磊,冯健. 各向异性和偏轴加载对1050车轮钢疲劳性能的影响[J]. 金属学报, 2017, 53(3): 307-315.
[7] 张骏,姚美意,冯炫凯,王志刚,黄娇,戴训,张金龙,周邦新. Zr-Sn-Fe-Cr-(Nb)合金在500 ℃过热蒸汽中的腐蚀各向异性研究*[J]. 金属学报, 2016, 52(12): 1565-1571.
[8] 陈守东,刘相华,刘立忠,宋孟. Cu极薄带轧制中滑移与变形的晶体塑性有限元模拟*[J]. 金属学报, 2016, 52(1): 120-128.
[9] 苟少秋,周邦新,谢世敬,徐龙,姚美意,李强. Zr-4合金在LiOH水溶液中腐蚀时氧化膜生长各向异性的研究*[J]. 金属学报, 2015, 51(8): 993-1000.
[10] 王效光,李嘉荣,喻健,刘世忠,史振学,岳晓岱. DD9单晶高温合金拉伸性能各向异性[J]. 金属学报, 2015, 51(10): 1253-1260.
[11] 刘永康, 黄海友, 谢建新. 连续柱状晶组织CuNi10Fe1Mn合金变形行为的各向异性[J]. 金属学报, 2015, 51(1): 40-48.
[12] 黄明亮, 张志杰, 冯晓飞, 赵宁. 液-固电迁移Ni/Sn-9Zn/Ni焊点反极性效应研究[J]. 金属学报, 2015, 51(1): 93-99.
[13] 邵媛媛, 杨平, 毛卫民. 电工钢柱状晶热、冷轧时晶界作用分析[J]. 金属学报, 2014, 50(3): 259-268.
[14] 卢磊, 尤泽升. 纳米孪晶金属塑性变形机制*[J]. 金属学报, 2014, 50(2): 129-136.
[15] 韩国民,韩志强,Alan A. Luo,Anil K. Sachdev,柳百成. Mg-Al合金Mg17Al12连续析出相形貌的相场模拟[J]. 金属学报, 2013, 49(3): 277-283.