臺灣博碩士論文加值系統

以電鍍的方式進行印刷電路板或矽晶圓微孔電鍍銅填充的技術已經廣泛應用在工業中。然而以高電流密度 (例如：10 ASD) 進行電鍍銅填充的製程卻尚未十分普及，這意味著高電流密度電鍍填孔尚有其難以控制的因素。本研究欲開發適合高電流密度填孔的配方，透過電化學分析了解哪些添加劑適合應用於高電流密度填孔，並推測其適合的原因，開發出能在10 ASD下進行電路板盲孔高速電鍍填充銅的配方。
從實驗結果中可以發現，氯離子在高電流密度電鍍中的比例需要微妙的控制，才能使抑制劑達到最好的抑制效果。此外，藉由比較不同高分子抑制劑對於填孔的影響，可以發現想要在高電流密度電鍍條件下有好的填孔表現，抑制劑的選擇有兩個特色，一是會隨對流越強而有越強的抑制性，二是擁有會傾向吸附於電子集中處的官能基( i.e. α-ammonium group, –NH3+)，可幫助抑制劑在高對流下對孔角的吸附，使電鍍銅在孔洞均勻沉積。在加速劑的選擇則是需使用具有耐操性且對於在高電流密度電鍍時，在陰極表面能穩定作用的添加劑。平整劑選用高分子類的，對於面銅厚度的抑制效果較小分子的平整劑來得好，面銅厚度可降至11μm，電鍍時間縮為15分鐘。

Microvia filling by copper electroplating technology has been widely used in industry. However, the technology was seldom used at high current density (i.e. 10 ASD). It means that it still has some problems when operating at high current density. Therefore, in this work, we will try to find out a formula of additives which is suitable for blind via electroplating process at 10 ASD. Based on the electrochemical analysis, we try to explore the mechanism of additives during the electroplating.
In order to have the strong inhibition for copper electroplating, the optimal concentration of chloride ion was found out. By comparing different kinds of polymer suppressors, two factors for high current density electroplating has been found. First, it should have convection- dependent inhibition, which means that the inhibition of the suppressor may be enhanced by increasing convection. Second, it should have the function group (i.e. α-ammonium group, –NH3+) which prefers to adsorb on the via opening where has lots of electrons. These characteristics make the copper electrodeposition more uniform at high current density electroplating. And the accelerators should be stable at high overpotential, to make sure that every vias were plated well. After adding polymer leveler, the board thickness was reduced to 11 μm which was better than monomer one. And the electroplating time was also shortened to 15 minutes.

摘要 i
Abstract ii
圖目錄 v
第1章 緒論 1
第2章 文獻回顧與理論 2
第2-1節 電化學理論[1] 2
2-1.1 電化學反應程序 2
2-1.2 極化與過電位 3
2-1.3 電子轉移控制與質傳控制 4
第2-2節 電化學分析原理與方法[1] 5
2-2.1 線性掃描伏安法 (Linear Sweep Voltammetry, LSV) 5
2-2.2 循環伏安法 (Cyclic Voltammetry, CV) 6
2-2.3 計時電位／電流分析法 7
第2-3節 電鍍原理與方法[1] 9
2-3.1 電鍍基本原理 9
2-3.2 電鍍之電源供應方式選擇 11
第2-4節 電鍍添加劑 13
2-4.1 支撐性電解質(Supporting Electrolyte) 13
2-4.2 氯離子 (Chloride ion) 14
2-4.3 抑制劑 (Suppressor) 16
2-4.4 加速劑 (Accelerater) 22
2-4.5 平整劑 (Leveler) 25
第2-5節 盲孔電鍍填充製程及理論 31
2-5.1 Adsorption Consumption Diffusion (ACD) 32
2-5.2 Curvature Enhanced Accelerator Coverage (CEAC) 32
2-5.3 Accelerator Accumulation (AA) 33
2-5.4 Convection Dependent Adsorption (CDA) 35
第3章 研究動機與目的 37
第4章 實驗藥品、裝置與步驟 39
第4-1節 實驗藥品 39
第4-2節 實驗裝置 40
4-2.1 電鍍實驗裝置 40
4-2.2 恆電位/電流儀 (Potentiostats / Galvanostats) 43
4-2.3 金相顯微鏡 (Optical Microscope, OM) 44
第4-3節 實驗步驟 45
4-3.1 哈林試驗槽電鍍實驗 45
4-3.2 電化學分析實驗 46
第5章 結果與討論 48
第5-1節 電鍍添加劑之電化學分析 48
5-1.1 氯離子濃度的影響 48
5-1.2 抑制劑的選擇 52
5-1.3 加速劑的選擇 56
5-1.4 平整劑的選擇 59
第5-2節 電鍍添加劑之實際電鍍結果 66
5-2.1 不同濃度的氯離子之電鍍填孔結果 66
5-2.2 不同抑制劑之電鍍填孔結果 67
5-2.3 不同加速劑之電鍍填孔結果 69
5-2.4 不同平整劑之電鍍填孔結果 71
第6章 結論 75
第7章 未來研究方向 76
第8章 參考文獻 77

[1]胡啟章, "電化學原理與方法," 五南出版, 中華民國96年.
[2]"Linear Sweep and Cyclic Voltametry: The Principles," https://www.ceb.cam.ac.uk/research/groups/rg-eme/teaching-notes/linear-sweep-and-cyclic-voltametry-the-principles.
[3]W. P. Dow and C. W. Liu, "Evaluating the filling performance of a copper plating formula using a simple galvanostat method," Journal of the Electrochemical Society, vol. 153, pp. C190-C194, 2006.
[4]D. Grujicic and B. Pesic, "Electrodeposition of copper: the nucleation mechanisms," Electrochimica Acta, vol. 47, pp. 2901-2912, 2002/07/18/ 2002.
[5]R. Liu, J. Duay, and S. B. Lee, "Heterogeneous nanostructured electrode materials for electrochemical energy storage," Chemical Communications, vol. 47, pp. 1384-1404, 2011.
[6]M. Kalantary, D. R. Gabe, and M. R. Goodenough, Unipolar and bipolar pulsed current electrodeposition for PCB production vol. 23, 1993.
[7]M. Georgiadou, D. Veyret, R. Sani, and R. Alkire, Simulation of Shape Evolution During Electrodeposition of Copper in the Presence of Additive vol. 148, 2001.
[8]P. Broekmann, M. Wilms, M. Kruft, C. Stuhlmann, and K. Wandelt, "In-situ STM investigation of specific anion adsorption on Cu(111)," Journal of Electroanalytical Chemistry, vol. 467, pp. 307-324, 1999/06/07/ 1999.
[9]Z. Nagy, J. P. Blaudeau, N. C. Hung, L. A. Curtiss, and D. J. Zurawski, "Chloride Ion Catalysis of the Copper Deposition Reaction," Journal of The Electrochemical Society, vol. 142, pp. L87-L89, June 1, 1995 1995.
[10]W. P. Dow, H. S. Huang, M. Y. Yen, and H. H. Chen, "Roles of chloride ion in microvia filling by copper electrodeposition - II. Studies using EPR and galvanostatic measurements," Journal of the Electrochemical Society, vol. 152, pp. C77-C88, 2005.
[11]W. Shao, G. Pattanaik, and G. Zangari, "Influence of Chloride Anions on the Mechanism of Copper Electrodeposition from Acidic Sulfate Electrolytes," Journal of The Electrochemical Society, vol. 154, pp. D201-D207, April 1, 2007 2007.
[12]J. W. Gallaway and A. C. West, "PEG, PPG, and Their Triblock Copolymers as Suppressors in Copper Electroplating," Journal of The Electrochemical Society, vol. 155, p. D632, 2008.
[13]J. J. Kelly and A. C. West, "Copper Deposition in the Presence of Polyethylene Glycol: I. Quartz Crystal Microbalance Study," Journal of The Electrochemical Society, vol. 145, pp. 3472-3476, October 1, 1998 1998.
[14]Z. V. Feng, X. Li, and A. A. Gewirth, "Inhibition Due to the Interaction of Polyethylene Glycol, Chloride, and Copper in Plating Baths: A Surface-Enhanced Raman Study," The Journal of Physical Chemistry B, vol. 107, pp. 9415-9423, 2003/09/01 2003.
[15]W.-P. Dow, M.-Y. Yen, W.-B. Lin, and S.-W. Ho, "Influence of Molecular Weight of Polyethylene Glycol on Microvia Filling by Copper Electroplating," Journal of The Electrochemical Society, vol. 152, p. C769, 2005.
[16]N. Xiao, N. Li, G. Cui, D. Tian, S. Yu, Q. Li, et al., "Triblock Copolymers as Suppressors for Microvia Filling via Copper Electroplating," Journal of the Electrochemical Society, vol. 160, pp. D188-D195, 2013.
[17]N. Xiao, D. Li, G. Cui, N. Li, D. Tian, Q. Li, et al., "An effective triblock copolymer as a suppressor for microvia filling via copper electrodeposition," Electrochimica Acta, vol. 109, pp. 226-232, 2013.
[18]N. Xiao, "Structural Effect of Polymers on Their Microvia Filling Performance as Suppressors During the Copper Electroplating," International Journal of Electrochemical Science, pp. 1453-1462, 2017.
[19]L.-H. Li, S. Yau, and W.-P. Dow, "In situ STM imaging of polyethylene glycol adsorbed on an Au(111) electrode in pH3," Electrochemistry Communications, vol. 70, pp. 1-4, 2016/09/01/ 2016.
[20]J. P. Healy, D. Pletcher, and M. Goodenough, "The chemistry of the additives in an acid copper electroplating bath: Part II. The instability 4,5-dithiaoctane-1,8-disulphonic acid in the bath on open circuit," Journal of Electroanalytical Chemistry, vol. 338, pp. 167-177, 1992/10/01/ 1992.
[21]E. E. Farndon, F. Walsh, and S. A. Campbell, Effect of thiourea, benzotriazole and 4,5-dithiaoctane-1,8-disulphonic acid on the kinetics of copper deposition from dilute acid sulphate solutions vol. 25, 1995.
[22]N. T. M. Hai, K. W. Krämer, A. Fluegel, M. Arnold, D. Mayer, and P. Broekmann, "Beyond interfacial anion/cation pairing: The role of Cu(I) coordination chemistry in additive-controlled copper plating," Electrochimica Acta, vol. 83, pp. 367-375, 2012.
[23]S. K. Cho, S.-K. Kim, and J. J. Kim, "Superconformal Cu Electrodeposition Using DPS," Journal of The Electrochemical Society, vol. 152, p. C330, 2005.
[24]S. K. Cho, M. J. Kim, H.-C. Koo, O. J. Kwon, and J. J. Kim, "Low-resistivity Cu film electrodeposited with 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonate for the application to the interconnection of electronic devices," Thin Solid Films, vol. 520, pp. 2136-2141, 2012.
[25]S. K. Kim, D. Josell, and T. P. Moffat, Cationic Surfactants for the Control of Overfill Bumps in Cu Superfilling vol. 153, 2006.
[26]S. K. Kim, D. Josell, and T. P. Moffat, "Electrodeposition of Cu in the PEI-PEG-Cl-SPS Additive System," Journal of The Electrochemical Society, vol. 153, p. C616, 2006.
[27]T. Y. Becky Leung, M. Kang, B. F. Corry, and A. Gewirth, Benzotriazole as an Additive for Copper Electrodeposition Influence of Triazole Ring Substitution vol. 147, 2000.
[28]W.-P. Dow, H.-S. Huang, M.-Y. Yen, and H.-C. Huang, "Influence of Convection-Dependent Adsorption of Additives on Microvia Filling by Copper Electroplating," Journal of The Electrochemical Society, vol. 152, p. C425, 2005.
[29]W.-P. Dow, C.-C. Li, M.-W. Lin, G.-W. Su, and C.-C. Huang, Copper Fill of Microvia Using a Thiol-Modified Cu Seed Layer and Various Levelers vol. 156, 2009.
[30]K. Umemoto, "Electrochemical Studies of the Reduction Mechanism of Tetrazolium Salts and Formazans," Bulletin of the Chemical Society of Japan, vol. 62, pp. 3783-3789, 1989/12/01 1989.
[31]P. Rapta, V. Brezová, M. ĉeppan, M. Melnik, D. Bustin, and A. Staŝko, "Radical Intermediates in the Redox Reactions of Tetrazolium Salts in Aprotic Solvents (Cyclovoltammetric, EPR and UV-VIS study)," Free Radical Research, vol. 20, pp. 71-82, 1994/01/01 1994.
[32]K. Umemoto, "Reduction Mechanism of 2,3,5-Triphenyltetrazolium Chloride and 1,3,5-Triphenylformazan," Bulletin of the Chemical Society of Japan, vol. 58, pp. 2051-2055, 1985/07/01 1985.
[33]T. Oritani, N. Fukuhara, T. Okajima, F. Kitamura, and T. Ohsaka, "Electrochemical and spectroscopic studies on electron-transfer reaction between novel water-soluble tetrazolium salts and a superoxide ion," Inorganica Chimica Acta, vol. 357, pp. 436-442, 2004/01/30/ 2004.
[34]S. Deng, X. Li, and H. Fu, "Nitrotetrazolium blue chloride as a novel corrosion inhibitor of steel in sulfuric acid solution," Corrosion Science, vol. 52, pp. 3840-3846, 2010.
[35]G. Y. Lin, J. J. Yan, M. Y. Yen, W. P. Dow, and S. M. Huang, "Characterization of Through-Hole Filling by Copper Electroplating Using a Tetrazolium Salt Inhibitor," Journal of the Electrochemical Society, vol. 160, pp. D3028-D3034, 2013.
[36]P. Broekmann, A. Fluegel, C. Emnet, M. Arnold, C. Roeger-Goepfert, A. Wagner, et al., "Classification of suppressor additives based on synergistic and antagonistic ensemble effects," Electrochimica Acta, vol. 56, pp. 4724-4734, 2011.
[37]Y. Zhu, S. Ma, X. Sun, J. Chen, M. Miao, and Y. Jin, "Numerical modeling and experimental verification of through silicon via (TSV) filling in presence of additives," Microelectronic Engineering, vol. 117, pp. 8-12, 2014.
[38]P. C. Andricacos, C. Uzoh, J. O. Dukovic, J. Horkans, and H. Deligianni, "Damascene Copper electroplating for chip interconnections," IBM J. Res. Dev., vol. 42, pp. 567-574, 1998.
[39]A. C. West, "Theory of Filling of High‐Aspect Ratio Trenches and Vias in Presence of Additives," Journal of The Electrochemical Society, vol. 147, pp. 227-232, January 1, 2000 2000.
[40]T. P. Moffat, D. Wheeler, W. H. Huber, and D. Josell, "Superconformal Electrodeposition of Copper," Electrochemical and Solid-State Letters, vol. 4, p. C26, 2001.
[41]T. P. Moffat and D. Josell, "Superconformal Electrodeposition for 3-Dimensional Interconnects," Israel Journal of Chemistry, vol. 50, pp. 312-320, 2010.
[42]K. Kondo, N. Yamakawa, Z. Tanaka, and K. Hayashi, "Copper damascene electrodeposition and additives," Journal of Electroanalytical Chemistry, vol. 559, pp. 137-142, 2003/11/15/ 2003.
[43]K. Kondo, T. Yonezawa, D. Mikami, T. Okubo, Y. Taguchi, K. Takahashi, et al., "High-Aspect-Ratio Copper-Via-Filling for Three-Dimensional Chip Stacking," Journal of The Electrochemical Society, vol. 152, p. H173, 2005.
[44]W. P. Dow, H. S. Huang, M. Y. Yen, and H. C. Huang, "Influence of convection-dependent adsorption of additives on microvia filling by copper electroplating," Journal of the Electrochemical Society, vol. 152, pp. C425-C434, 2005.
[45]W. P. Dow, M. Y. Yen, S. Z. Liao, Y. D. Chiu, and H. C. Huang, "Filling mechanism in microvia metallization by copper electroplating," Electrochimica Acta, vol. 53, pp. 8228-8237, Nov 2008.
[46]H. Y. Wang, P. Cheng, H. Wang, R. Liu, L. M. Sun, Q. L. Rao, et al., "Effect of current density on microstructure and mechanical property of Cu micro-cylinders electrodeposited in through silicon vias," Materials Characterization, vol. 109, pp. 164-172, Nov 2015.
[47]Y. Zhang, G. Ding, H. Wang, P. Cheng, and R. Liu, "Optimization of innovative approaches to the shortening of filling times in 3D integrated through-silicon vias (TSVs)," Journal of Micromechanics and Microengineering, vol. 25, p. 045009, 2015.
[48]H. Y. Cao, T. Hang, H. Q. Ling, L. M. Gao, and M. Li, "Linear Sweep Voltammetric Study on the Copper Electrodeposition of Though-Silicon-Vias," Journal of the Electrochemical Society, vol. 161, pp. D349-D352, 2014.
[49]W. Luo, J. H. Zhang, Z. P. Chen, Y. Zhu, L. M. Gao, and M. Li, "Modeling the Copper Electrodeposition of Through-silicon-vias Corresponded to Linear Sweep Voltammetry," Electrochemistry, vol. 84, pp. 516-522, Jul 2016.
[50]T. Lu, F. Wang, and Y. He, "Influence of the Chemical Structure of Gemini Quaternary Ammonium Compounds on Copper Electrodeposition," Journal of The Electrochemical Society, vol. 163, pp. D663-D671, 2016.
[51]T. H. Tsai and J. H. Huang, "Copper electrodeposition in a through-silicon via evaluated by rotating disc electrode techniques," Journal of Micromechanics and Microengineering, vol. 20, p. 5, Nov 2010.
[52]Q. S. Zhu, A. Toda, Y. Zhang, T. Itoh, and R. Maeda, "Void-Free Copper Filling of Through Silicon Via by Periodic Pulse Reverse Electrodeposition," Journal of the Electrochemical Society, vol. 161, pp. D263-D268, 2014.
[53]K. Kondo, Y. Yamada, and M. Yokoi, "TSV Fillings and Electrochemical Measurements of the Dialyl-amine Additive with Cl- and Br," Journal of the Electrochemical Society, vol. 162, pp. D397-D400, 2015.
[54]S. C. Hong, W. G. Lee, W. J. Kim, J. H. Kim, and J. P. Jung, "Reduction of defects in TSV filled with Cu by high-speed 3-step PPR for 3D Si chip stacking," Microelectronics Reliability, vol. 51, pp. 2228-2235, Dec 2011.
[55]M. Hayase and M. Nagao, "Copper Deep Via Filling with Selective Accelerator Deactivation by Polyethyleneimine," Journal of the Electrochemical Society, vol. 160, pp. D3216-D3220, 2013.
[56]H. C. Kim, S. Choe, J. Y. Cho, D. Lee, I. Jung, W. S. Cho, et al., "Bottom-up Filling of through Silicon Vias Using Galvanostatic Cu Electrodeposition with the Modified Organic Additives," Journal of the Electrochemical Society, vol. 162, pp. D109-D114, 2015.
[57]M. J. Kim, Y. Seo, H. C. Kim, Y. Lee, S. Choe, Y. G. Kim, et al., "Galvanostatic bottom-up filling of TSV-like trenches: Choline-based leveler containing two quaternary ammoniums," Electrochimica Acta, vol. 163, pp. 174-181, May 2015.
[58]J. Y. Lee, S. W. Lee, S. K. Lee, and J. H. Park, "Through-glass copper via using the glass reflow and seedless electroplating processes for wafer-level RF MEMS packaging," Journal of Micromechanics and Microengineering, vol. 23, Aug 2013.
[59]Z. W. Lei, L. Chen, W. L. Wang, Z. L. Wang, and C. Zhao, "Tetrazole Derived Levelers for Filling Electroplated Cu Microvias: Electrochemical Behaviors and Quantum Calculations," Electrochimica Acta, vol. 178, pp. 546-554, Oct 2015.
[60]C. Chang, X. B. Lu, Z. W. Lei, Z. L. Wang, and C. Zhao, "2-Mercaptopyridine as a new leveler for bottom-up filling of micro-vias in copper electroplating," Electrochimica Acta, vol. 208, pp. 33-38, Aug 2016.
[61]P. F. Chan, Y. D. Chiu, W. P. Dow, K. Krug, Y. L. Lee, and S. L. Yau, "Use of 3,3-Thiobis(1-propanesulfonate) to Accelerate Microvia Filling by Copper Electroplating," Journal of the Electrochemical Society, vol. 160, pp. D3271-D3277, 2013.
[62]C. F. Hsu, W. P. Dow, H. C. Chang, and W. Y. Chiu, "Optimization of the Copper Plating Process Using the Taguchi Experimental Design Method I. Microvia Filling by Copper Plating Using Dual Levelers," Journal of the Electrochemical Society, vol. 162, pp. D525-D530, 2015.
[63]W. P. Dow, C. C. Li, Y. C. Su, S. P. Shen, C. C. Huang, C. Lee, et al., "Microvia filling by copper electroplating using diazine black as a leveler," Electrochimica Acta, vol. 54, pp. 5894-5901, Oct 2009.
[64]C. E. Ho, C. C. Chen, H. Hsu, and M. K. Lu, "Electron backscatter diffraction characterization of electrolytic Cu deposition in the blind-hole structure: Current density effect," Thin Solid Films, vol. 584, pp. 78-84, Jun 2015.
[65]C. E. Ho, L. H. Hsu, C. C. Chen, and M. K. Lu, "Electron backscatter diffraction characterization of blind hole fillings by electrolytic Cu deposition," Thin Solid Films, vol. 572, pp. 232-237, Dec 2014.
[66]W. P. Dow, C. C. Li, M. W. Lin, G. W. Su, and C. C. Huang, "Copper Fill of Microvia Using a Thiol-Modified Cu Seed Layer and Various Levelers," Journal of the Electrochemical Society, vol. 156, pp. D314-D320, 2009.
[67]Q. S. Zhu, A. Toda, Y. Zhang, T. Itoh, and R. Maeda, "High-Speed Copper Filling within High Aspect Ratio Through Holes in Polymer Substrates," International Journal of Electrochemical Science, vol. 8, pp. 10568-10577, Aug 2013.
[68]W.-P. Dow, H.-H. Chen, M.-Y. Yen, W.-H. Chen, K.-H. Hsu, P.-Y. Chuang, et al., "Through-Hole Filling by Copper Electroplating," Journal of The Electrochemical Society, vol. 155, p. D750, 2008.
[69]J. J. Yan, L. C. Chang, C. W. Lu, and W. P. Dow, "Effects of organic acids on through-hole filling by copper electroplating," Electrochimica Acta, vol. 109, pp. 1-12, Oct 2013.
[70]E. K. Yung and L. T. Romankiw, "FUNDAMENTAL-STUDY OF ACID COPPER THROUGH-HOLE ELECTROPLATING PROCESS," Journal of the Electrochemical Society, vol. 136, pp. 756-767, Mar 1989.
[71]J. Liu, J. D. Chen, Z. Zhang, J. L. Yang, W. He, and S. J. Chen, "A copper electroplating formula for BVHs and THs filling at one process," Circuit World, vol. 42, pp. 141-151, 2016.
[72]C. H. Chen, C. W. Lu, S. M. Huang, and W. P. Dow, "Effects of supporting electrolytes on copper electroplating for filling through-hole," Electrochimica Acta, vol. 56, pp. 5954-5960, Jul 2011.
[73]Y. Z. Zhang, H. Y. Wang, Y. N. Sun, K. F. Wu, H. Wang, P. Cheng, et al., "Copper electroplating technique for efficient manufacturing of low-cost silicon interposers," Microelectronic Engineering, vol. 150, pp. 39-42, Jan 2016.
[74]T. C. Chen, Y. L. Tsai, C. F. Hsu, W. P. Dow, and Y. Hashimoto, "Effects of Brighteners in a Copper Plating Bath on Throwing Power and Thermal Reliability of Plated Through Holes," Electrochimica Acta, vol. 212, pp. 572-582, Sep 2016.
[75]M. Schwartz, W. Li, N. H. Phan, K. Nobe, and A. J. Pearlstein, "PLATING OF COPPER IN TUBULAR HOLES WITH ROTATING SCREW ELECTRODES," Surface & Coatings Technology, vol. 52, pp. 269-274, May 1992.
[76]P.-F. Chan, R.-H. Ren, S.-I. Wen, H.-C. Chang, and W.-P. Dow, "Effects of Additives and Convection on Cu Foil Fabrication with a Low Surface Roughness," Journal of The Electrochemical Society, vol. 164, pp. D660-D665, 2017.
[77]劉筑綺, "尺寸安定性陽極用於高速填孔電鍍銅," 國立中興大學化學工程學系碩士論文, 中華民國105年.
[78]盧俊瑋, "通孔填充電鍍銅之配方開發," 國立中興大學化學工程學系碩士論文, 中華民國97年.
[79]I. Tabakovic, S. Riemer, and M. Sun, "Self-Assembled Monolayer of 3-N, N-Dimethylaminodithiocarbamoyl-1-Propanesulfonic Acid (DPS) Used in Electrodeposition of Copper," Journal of the Electrochemical Society, vol. 160, pp. D3197-D3205, 2013.