Excellent Oxidation Resistance and Solder Wettability of (111)-Oriented Nanotwinned Cu

doi:10.11900/0412.1961.2022.00334

Acta Metall Sin

2024, Vol. 60

Issue (7): 957-967 DOI: 10.11900/0412.1961.2022.00334

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Excellent Oxidation Resistance and Solder Wettability of (111)-Oriented Nanotwinned Cu

XU Zengguang¹^,²^,³, ZHOU Shiqi¹^,³, LI Xiao¹^,³, LIU Zhiquan¹^,²^,³(

)

1 Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
2 Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Shenzhen 518055, China
3 Shenzhen Institute of Advanced Electronic Materials, Shenzhen 518103, China

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XU Zengguang, ZHOU Shiqi, LI Xiao, LIU Zhiquan. Excellent Oxidation Resistance and Solder Wettability of (111)-Oriented Nanotwinned Cu. Acta Metall Sin, 2024, 60(7): 957-967.

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Abstract

In the advanced-packaging industry, (111)-oriented nanotwinned copper ((111)nt-Cu) offers several advantages over common randomly oriented equiaxed polycrystalline Cu (C-Cu), including high strength, excellent elongation, and promising electrical conductivity. In recent years, (111)nt-Cu has shown potential for becoming a C-Cu replacement in under-bump metallization and redistribution layer applications. This shift is attributed to the escalating demand for thermal stability and enhanced electrical and mechanical performances of Cu materials amid the rapid transition toward three-dimensional electronic packaging. This study proposed that (111)nt-Cu exhibits better oxidation resistance than C-Cu after aging in air at 250^oC. The thickness and composition of (111)nt-Cu and C-Cu oxide layers were analyzed respectively via TEM and XPS. Various grain boundaries on the surface of the prepared (111)nt-Cu and C-Cu substrates were evaluated using EBSD and FIB techniques. The morphology at the interface between the two Cu substrates and their oxide layers was characterized using SEM. In addition, the solderability of the oxidized layers was assessed by measuring the wetting angles and spreading areas of the involved Sn-Cu joint structures. Results show that when the oxidation time was 9 min, the thickness of the (111)nt-Cu oxide layer was 43.2% lesser than that of the C-Cu oxide layer. After 12 min of oxidation, the contact angle between Sn and oxidized (111)nt-Cu was 26.7% smaller than that between Sn and oxidized C-Cu, while the spreading area of Sn on (111)nt-Cu was 24.6% larger than that of Sn on C-Cu. After oxidation, the surface layers of both Cu substrates comprised CuO and Cu₂O nanocrystals coexisting within the same layer. Because oxidation is closely related to the diffusion of Cu atoms through grain boundaries, the grain boundaries of both Cu substrates were investigated in the natural-growth direction. The results show that compared to C-Cu, (111)nt-Cu has a lower surface energy and smaller area fraction of high angle grain boundaries, effectively limiting the outward-diffusion rate of Cu atoms.

Key words: (111)-oriented nanotwinned copper randomly oriented equiaxed polycrystalline copper oxi-dation resistance soldering wettability grain boundary diffusion

Received: 08 July 2022

ZTFLH:

TN405

Fund: National Natural Science Foundation of China(62274172);Guangdong Basic and Applied Basic Research Foundation(2022B1515120037)

Corresponding Authors: LIU Zhiquan, professor, Tel: 18624083161, E-mail: zqliu@siat.ac.cn

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https://www.ams.org.cn/EN/10.11900/0412.1961.2022.00334 OR https://www.ams.org.cn/EN/Y2024/V60/I7/957

Fig.1 Electroplating process for the deposition of (111)-oriented nanotwinned copper ((111)nt-Cu)

Fig.2 Color changes of the surfaces of (111)nt-Cu (a1-a5) and common randomly oriented equiaxed polycrystalline Cu (C-Cu) (b1-b5) samples after oxidation at 250^oC for 0 min (a1, b1), 3 min (a2, b2), 6 min (a3, b3), 9 min (a4, b4), and 12 min (a5, b5) (The dimension of the individule sample is 1 cm × 1 cm)

Fig.3 XPS analyses of the surface of (111)nt-Cu and C-Cu samples after oxidation
(a) 2p orbital spectrum of (111)nt-Cu
(b) LM2 orbital spectrum of (111)nt-Cu
(c) depth profiles of the content of O in (111)nt-Cu and C-Cu samples after oxidation

Fig.4 SEM (a, c) and FIB (b, d) images of the cross sections of (111)nt-Cu (a, b) and C-Cu (c, d) samples after oxidation

Fig.5 TEM bright field images of the cross sections of (111)nt-Cu (a) and C-Cu (b) samples after oxidation, and the corresponding HRTEM images (c, d) as well as selected area electron diffraction (SAED) patterns (e, f) of the oxide layer

Fig.6 Contact angles of solder bumps on (111)nt-Cu and C-Cu samples with oxidation time at 250^oC

Fig.7 Spreading cloud images of the solder bump on the surfaces of (111)nt-Cu (a-c) and C-Cu (d-f) samples oxidized at 250^oC for 0 min (a, d), 3 min (b, e), and 12 min (c, f)

Table 1 Spreading areas of the solder bump on the surfaces of (111)nt-Cu and C-Cu samples oxidized at 250^oC for different time

Fig.8 EBSD images of the original surfaces of (111)nt-Cu (a) and C-Cu (b) samples showing the grain boundry and twin boundary in the normal direction, as well as those of FIB surface images (c, d) after oxidation

Table 2 Statistical data of grain boundaries of (111)nt-Cu and C-Cu samples

Fig.9 Grain misorientation distributions (a, b) and grain size distributions (c, d) of (111)nt-Cu (a, c) and C-Cu (b, d) samples

Fig.10 Cross section FIB images of electroplated (111)nt-Cu (a) and C-Cu (b) samples; diffution illustrations of Cu atom on grain boundaries in (111)nt-Cu (c) and C-Cu (d) samples (J_Cu1—Cu diffusion flux in (111)nt-Cu along the grain boundary; J_Cu2—Cu diffusion flux in C-Cu along the grain bounadry)

1	Huang J, Li Z G, Gao L Y, et al. Effect of methylene blue on the microstructure and mechanical properties of nanotwinned copper during DC electroplating [J]. J. Integr. Technol., 2021, 10(1): 55
	黄静, 李忠国, 高丽茵等. 亚甲基蓝对直流电镀纳米孪晶铜组织及力学性能的影响 [J]. 集成技术, 2021, 10(1): 55
2	Ko C T, Chen K N. Wafer-level bonding/stacking technology for 3D integration [J]. Microelectron. Reliab., 2010, 50: 481
3	Li X, Luo J X. The oxidation of copper at 200-900^oC [J]. Acta Metall. Sin., 1965, 8: 311
	李薰, 骆继勋. 铜在200~900℃的氧化 [J]. 金属学报, 1965, 8: 311
4	Kusano K F, Uchikoshi M, Mimura K, et al. Low-temperature oxidation of Cu(100), Cu(110) and Cu(111) [J]. Oxid. Met., 2014, 82: 181
5	Young F W, Cathcart J V, Gwathmey A T. The rates of oxidation of several faces of a single crystal of copper as determined with elliptically polarized light [J]. Acta Metall., 1956, 4: 145
6	Hsiao H Y, Liu C M, Lin H W, et al. Unidirectional growth of microbumps on (111)-oriented and nanotwinned copper [J]. Science, 2012, 336: 1007
7	Lu L, Shen Y F, Chen X H, et al. Ultrahigh strength and high electrical conductivity in copper [J]. Science, 2004, 304: 422 pmid: 15031435
8	Guo J Y, Wang K, Lu L. Tensile properties of Cu with deformation twins induced by SMAT [J]. J. Mater. Sci. Technol., 2006, 22: 789
9	Lu K, Lu L, Suresh S. Strengthening materials by engineering coherent internal boundaries at the nanoscale [J]. Science, 2009, 324: 349 doi: 10.1126/science.1159610 pmid: 19372422
10	Lu L, Chen X, Huang X, et al. Revealing the maximum strength in nanotwinned copper [J]. Science, 2009, 323: 607 doi: 10.1126/science.1167641 pmid: 19179523
11	Sun F L, Liu Z Q, Li C F, et al. Bottom-up electrodeposition of large-scale nanotwinned copper within 3D through silicon via [J]. Materials., 2018, 11: 319
12	Juang J Y, Shie K C, Hsu P N, et al. Low-resistance and high-strength copper direct bonding in no-vacuum ambient using highly (111)-oriented nano-twinned copper [A]. 2019 IEEE 69th Electronic Components and Technology Conference (ECTC) [C]. Las Vegas: Institute of Electrical and Electronics Engineers, 2019: 642
13	Liu C M, Lin H W, Huang Y S, et al. Low-temperature direct copper-to-copper bonding enabled by creep on (111) surfaces of nanotwinned Cu [J]. Sci. Rep., 2015, 5: 9734
14	Agrawal P M, Rice B M, Thompson D L. Predicting trends in rate parameters for self-diffusion on FCC metal surfaces [J]. Surf. Sci., 2002, 515: 21
15	Lin H W, Lu C L, Liu C M, et al. Microstructure control of unidirectional growth of η-Cu₆Sn₅ in microbumps on 〈111〉 oriented and nanotwinned Cu [J]. Acta Mater., 2013, 61: 4910
16	Zhou S Q, Zhang Y B, Gao L Y, et al. The self-healing of Kirkendall voids on the interface between Sn and (111) oriented nanotwinned Cu under thermal aging [J]. Appl. Surf. Sci., 2022, 588: 152900
17	Tseng C H, Tu K N, Chen C. Comparison of oxidation in uni-directionally and randomly oriented Cu films for low temperature Cu-to-Cu direct bonding [J]. Sci. Rep., 2018, 8: 10671
18	Zhang M H, Gao L Y, Wang Y X, et al. Micro-cones Cu fabricated by pulse electrodeposition for solderless Cu-Cu direct bonding [J]. Appl. Surf. Sci., 2024, 650: 159184
19	Wen S M, Wang B L, Zhao C W, et al. Study on microstructure and hardness of direct-current electrodeposited nanotwinned Cu [J]. Hot Working Technol., 2017, 46(12): 107
	温淑敏, 王博林, 赵春旺等. 直流电解沉积纳米孪晶铜的微观结构与硬度研究 [J]. 热加工工艺, 2017, 46(12): 107
20	Li Z G, Gao L Y, Liu Z Q. The effect of transition layer on the strength of nanotwinned copper film by DC electrodeposition [A]. 21st International Conference on Electronic Packaging Technology (ICEPT) [C]. Guangzhou: Institute of Electrical and Electronics Engineers, 2020: 1
21	Li Z G, Gao L Y, Li Z, et al. Regulating the orientation and distribution of nanotwins by trace of gelatin during direct current electroplating copper on titanium substrate [J]. J. Mater. Sci., 2022, 57: 17797
22	Xiao J W. Investigation on mechanical properties of nanotwinned diamond and nanotwinned copper [D]. Qinhuangdao: Yanshan University, 2018
	肖建伟. 纳米孪晶金刚石和纳米孪晶铜的力学性质研究 [D]. 秦皇岛: 燕山大学, 2018
23	Lu K. Stabilizing nanostructures in metals using grain and twin boundary architectures [J]. Nat. Rev. Mater., 2016, 1: 16019
24	Sun L G, He X Q, Lu J. Nanotwinned and hierarchical nanotwinned metals: A review of experimental, computational and theoretical efforts [J]. npj Comput. Mater., 2018, 4: 6
25	Liu J. Fatigue fracture analysis of nano-twinned copper under cyclic tensile loading [D]. Harbin: Harbin Engineering University, 2021
	刘进. 循环拉伸载荷下纳米孪晶铜的疲劳断裂分析 [D]. 哈尔滨: 哈尔滨工程大学, 2021
26	Pan Q S, Lu L. Dislocation characterization in fatigued Cu with nanoscale twins [J]. Sci. China Mater., 2015, 58: 915
27	Zhou X L, Li X Y, Chen C Q. Atomistic mechanisms of fatigue in nanotwinned metals [J]. Acta Mater., 2015, 99: 77
28	Pan Q S, Zhou H F, Lu Q H, et al. History-independent cyclic response of nanotwinned metals [J]. Nature, 2017, 551: 214
29	Cheng Z, Zhou H F, Lu Q H, et al. Extra strengthening and work hardening in gradient nanotwinned metals [J]. Science, 2018, 362:eaau1925
30	Zhang Y B, Gao L Y, Tao J L, et al. The mechanical property and microstructural thermal stability of gradient-microstructured nanotwinned copper films electroplated on the high (111)-orientated sub-strates [J]. Mater. Today Commun., 2024, 38: 108182
31	Sun F L, Gao L Y, Liu Z Q, et al. Electrodeposition and growth mechanism of preferentially orientated nanotwinned Cu on silicon wafer substrate [J]. J. Mater. Sci. Technol., 2018, 34: 1885
32	Zhang Y B, Gao L Y, Li X, et al. Electroplating nanotwinned copper for ultrafine pitch redistribution layer (RDL) of advanced packaging technology [A]. 22nd International Conference on Electronic Packaging Technology (ICEPT) [C]. Xiamen: Institute of Electrical and Electronics Engineers, 2021: 1
33	Zhang Y B. Research on preparation and reliability of nanotwinned copper interconnect materials for microelectronic packaging [D]. Harbin: Harbin University of Science and Technology, 2022
	张玉博. 微电子封装用纳米孪晶铜互连材料的制备及可靠性研究 [D]. 哈尔滨: 哈尔滨理工大学, 2022
34	Kuroyanagi T. Copper and its alloy [J]. J. Met. Finish. Soc., 1980, 31: 432
	黒柳卓. 銅·銅合金 [J]. 金属表面技術, 1980, 31: 432
35	Nakata S. Regarding discoloration of copper and copper alloys [J]. Corros. Eng. Dig., 1959, 8: 291
	仲田進一. 銅および銅合金の変色について [J]. 防蝕技術, 1959, 8: 291
36	Biesinger M C, Lau L W M, Gerson A R, et al. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn [J]. Appl. Surf. Sci., 2010, 257: 887
37	Lu Z H. Study on the oxidation behavior of single crystal copper [D]. Lanzhou: Lanzhou University of Technology, 2010
	卢振华. 单晶铜氧化行为的研究 [D]. 兰州: 兰州理工大学, 2010
38	Shang P J, Liu Z Q, Pang X Y, et al. Growth mechanisms of Cu₃Sn on polycrystalline and single crystalline Cu substrates [J]. Acta Mater., 2009, 57: 4697
39	Askeland D R, Phule P P. The Science and Engineering of Materials [M]. 4th Ed., London: Brooks/Cole Publishing/Thompson Learning, 2003: 86
40	Huang M L, Wu Y. Growth mechanism of interfacial IMCs on (111) preferred orientation nanotwinned Cu UBM for 3D IC packaging [A]. 2020 IEEE 70th Electronic Components and Technology Conference (ECTC) [C]. Orlando: Institute of Electrical and Electronics Engineers, 2020: 1881
41	Han Z, Lu L, Zhang H W, et al. Comparison of the oxidation behavior of nanocrystalline and coarse-grain copper [J]. Oxid. Met., 2005, 63: 261
42	Zhang L, Liu Z Q. Inhibition of intermetallic compounds growth at Sn-58Bi / Cu interface bearing CuZnAl memory particles (2-6 μm) [J]. J. Mater. Sci.: Mater. Electron., 2020, 31: 2466

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