Chemical Components and Its Functions of Polishing Solution Used in Electrogenerated Chemical Polishing of Copper

doi:10.3901/JME.2016.05.088

Abstract

Abstract: Electrogenerated chemical polishing (EGCP) is a new, stress-free polishing method. Stress free polishing of workpiece surface is realized by diffusion controlled chemical reaction and etchant is generated by electrochemical reaction on electrode surface. The components of polishing solution are the key factors to realize the diffusion controlled reaction and controllable material removal process. The basic principle of EGCP is analyzed, and the basic characteristics of polishing solution are proposed according to the theoretical analysis. For realizing EGCP of Cu, the FeSO₄(redox mediator), H₂SO₄ (pH adjusting agent) and BTA (lateral charge propagation inhibitor) are chosen as the polishing solution. Through analyzing the surface components of polished workpiece by XPS and XRD, the action mechanisms of H₂SO₄ and BTA are studied. The results show that the H₂SO₄ is benefit to promoting the etching reaction through removing the Cu oxide layer. BTA can be adsorbed on the Cu surface, and then suppresses surface lateral charge propagation.

Key words: electrochemistry reaction, electrogenerated chemical polishing, polishing solution, roughness

CLC Number:

TN305

SHAN Kun, ZHOU Ping, CAI Jiqing, KANG Renke, GUO Dongming. Chemical Components and Its Functions of Polishing Solution Used in Electrogenerated Chemical Polishing of Copper[J]. Journal of Mechanical Engineering, 2016, 52(5): 88-94.

References

[1] JAHNES C V, COTTE J,LUND J L,et al. Simultaneous fabrication of RF MEMS switches and resonators using copper-based CMOS interconnect manufacturing methods[C]// Micro Electro Mechanical Systems, 2004. 17th IEEE International Conference on (MEMS),2004：789 - 792.
[2] KIRINO O,ENOMOTO T. Ultra-flat and ultra-smooth Cu surfaces produced by abrasive-free chemical-mechanical planarization/polishing using vacuum ultraviolet light[J]. Precision Engineering,2011,35(4): 669-676.
[3] 郭东明,康仁科,苏建修,等. 超大规模集成电路制造中硅片平坦化技术的未来发展[J]. 机械工程学报. 2003,39(10)：100-105.
GUO Dongming,KANG Renke,SU Jianxiu,et al. Future development on wafer planarization technology in ULSI fabrication[J]. Chinese Journal of Mechanical Engineering,2003,39(10)：100-105.
[4] JORNE J. Challenges in copper interconnect technology：Macro-uniformity and micro-filling power in copper electroplating of wafers[J]. Semiconductor Fabtech,2000,11(1)：267-71.
[5] KRISHNAN M,NALASKOWSKI J W,COOK L M. Chemical mechanical planarization：Slurry chemistry,materials,and mechanisms[J]. Chemical reviews,2009,110(1)：178-204.
[6] ZHONG Z W. Recent advances in polishing of advanced materials[J]. Materials and Manufacturing Processes,2008,23(5)：449-456.
[7] XU J,LUO J B,WANG L L,et al. The crystallographic change in sub-surface layer of the silicon single crystal polished by chemical mechanical polishing[J]. Tribology International,2007,40(2)：285-289.
[8] NIEWCZAS M,BASINSKI Z S,BASINSKI S J,et al. Deformation of copper single crystals to large strains at 4.2 K：I. Mechanical response and electrical resistivity[J]. Philosophical Magazine A,2001,81(5)：1121-1142.
[9] POLAK J. Electrical resistivity of cyclically deformed copper[J]. Czechoslovak Journal of Physics B. 1969,19(3)：315-322.
[10] CAKIR O,TEMEL H,KIYAK M. Chemical etching of Cu-ETP copper[J]. Journal of Materials Processing Technology,2005,162：275-279.
[11] CAKIR O. Copper etching with cupric chloride and regeneration of waste etchant[J]. Journal of Materials Processing Technology,2006,175(1)：63-68.
[12] HUO J,MCANDREW J,SOLANKI R. Electrochemical planarization of patterned copper films for microelectronic applications[J]. Journal of Materials Engineering and Performance,2004,13(4)：413-420.
[13] LANDOLT D. Fundamental aspects of electropolishing [J]. Electrochimica Acta,1987,32(1)：1-11.
[14] STOGNIJ A I,NOVITSKII N N,STUKALOV O M. Nanoscale ion beam polishing of optical materials[J]. Technical Physics Letters,2002,28(1)：17-20.
[15] COBURN J W,WINTERS H F. Ion-and electron-assisted gas-surface chemistry—An important effect in plasma etching [J]. Journal of Applied Physics,1979,50(5)：3189-3196.
[16] LIU H Y,FAN F R F,LIN C W,et al. Scanning electrochemical and tunneling ultramicroelectrode microscope for high-resolution examination of electrode surfaces in solution[J]. Journal of the American Chemical Society,1986,108(13)：3838-3839.
[17] LEFROU C. A unified new analytical approximation for positive feedback currents with a microdisk SECM tip[J]. Journal of Electroanalytical Chemistry,2006,592(1)：103-112.
[18] MANDLER D,BARD A J. Scanning electrochemical microscopy：The application of the feedback mode for high resolution copper etching[J]. Journal of the Electrochemical Society,1989,136(10)：3143-3144.
[19] CORNUT R,NUNIGE S,LEFROU C,et al. Local etching of copper films by the scanning electrochemical microscope in the feedback mode：A theoretical and experimental investigation[J]. Electrochimica Acta,2011,56(28)：10701-10707.
[20] SHEFFER M,MANDLER D. Why is copper locally etched by scanning electrochemical microscopy[J]. Journal of Electroanalytical Chemistry,2008,622(1)：120-129.
[21] SHAN K,ZHOU P,CAI J,et al. Electrogenerated chemical polishing of copper[J]. Precision Engineering, 2015,39：161-166.
[22] 周平,康仁科,单坤,等. 电致化学抛光方法： CN103924287A[P]. 2014-07-16.
ZHOU Ping,KANG Renke,SHAN Kun,et al. Method of electrogenerated chemical polishing：CN 103924287A [P]. 2014-07-16.
[23] 吴宏基,曹利新,刘健. 基于行星式平面研磨机研抛过程的运动几何学分析[J]. 机械工程学报,2002,38(6)：144-147.
WU Hongji,CAO Lixin,LIU Jian. Analysis of kinematic geometry on face grinding process on lapping machines[J]. Chinese Journal of Mechanical Engineering,2002,38(6)：144-147.
[24] PRESTON F W. The theory and design of plate glass polishing machines[J]. J. Soc. Glass Tech.,1927,11：214.
[25] MANSIKKAMÄKI K,AHONEN P,FABRICIUS G,et al. Inhibitive effect of benzotriazole on copper surfaces studied by SECM[J]. Journal of the Electrochemical Society,2005,152(1)：B12-B16.
[26] MANSIKKAMÄKI K,HAAPANEN U,JOHANS C,et al. Adsorption of benzotriazole on the surface of copper alloys studied by SECM and XPS[J]. Journal of the Electrochemical Society. 2006,153(8)：B311.
[27] XUE G,DING J. Chemisorption of a compact polymeric coating on copper surfaces from a benzotriazole solution[J]. Applied Surface Science,1990,40(4)：327-332.