不同氧化剂对6H-SiC化学机械抛光的影响

doi:10.3901/JME.2018.19.224

摘要/Abstract

摘要： 选用胶体SiO₂纳米颗粒为磨粒，研究不同pH值条件下高锰酸钾和双氧水两种氧化剂对6H-SiC晶片化学机械抛光的影响，并使用原子力显微镜观察抛光后表面质量。采用Zeta电位分析仪分析溶液中胶体SiO₂颗粒的Zeta电位，采用X射线光电子能谱分析SiC抛光表面元素及其化学状态。结果表明：SiC晶片的材料去除率随pH值变化而变化，采用高猛酸钾抛光液抛光时，材料去除率在pH 6时达到峰值185 nm/h，R_a为0.25 nm；采用双氧水抛光液抛光时，材料去除率在pH 8时达到峰值110 nm/h，R_a为0.32 nm。pH值低于5时，电负性的SiO₂颗粒会通过静电作用吸附在带正电的SiC表面，抑制SiC晶片表面原子的氧化及去除，降低材料去除率；pH值高于5时，SiO₂颗粒在双氧水抛光液中的静电排斥力弱于高锰酸钾抛光液中静电排斥力，从而影响了SiO₂颗粒的分散性能，降低了抛光效果。采用高锰酸钾抛光液抛光后，SiC晶片表面的Si-C氧化产物含量（Si-C-O、Si₄C_4-xO₂和Si₄C₄O₄）较高，高锰酸钾抛光液的氧化能力较强。

关键词: 二氧化硅颗粒, 高锰酸钾, 化学机械抛光, 双氧水, 碳化硅

Abstract: The chemical mechanical polishing (CMP) performance of Si-face 6H-SiC substrates are compared between two different oxidizers (KMnO₄ and H₂O₂) under different pH values, using colloidal silica nanoparticles as abrasives. The surface morphology of the polished SiC substrate is characterized using atomic force microscope (AFM). The Zeta potentials of silica particles in different solutions are investigated using zeta potential analyzer and the chemical composition of the polished surfaces is studied using X-ray photoelectron spectroscopy (XPS). The results indicate that there is a significant difference in the material removal rates (RRs) of 6H-SiC under different pH values. For the KMnO₄ based slurries, the maximum RRs (185 nm/h) with an average roughness Ra of 0.25 nm is achieved at pH 6; for the H₂O₂ based slurries, the maximum RRs (110 nm/h) with an average roughness Ra of 0.32 nm is achieved at pH 8. Negative charged silica particles are expected to be attracted by positive charged SiC surface below pH 5, which might reduce the oxidation and removal of the SiC substrate; the electrostatic repulsive force of silica particles in the H₂O₂ based slurries is less than in the KMnO₄ based slurries, thus influencing the dispersion properties of silica particles. The concentrations of the oxidized species of Si-C (Si-C-O, Si₄C_4-xO₂ and Si₄C₄O₄) are higher in the SiC surface polished with KMnO₄ than in the pre-polished SiC surface and the surface polished with H₂O₂, which due to the higher oxidizing ability of KMnO₄ than H₂O₂.

Key words: chemical mechanical polishing (CMP), H₂O₂, KMnO₄, silica particles, silicon carbide (SiC)

中图分类号:

TH161

倪自丰, 陈国美, 徐来军, 白亚雯, 李庆忠, 赵永武. 不同氧化剂对6H-SiC化学机械抛光的影响[J]. 机械工程学报, 2018, 54(19): 224-231.

NI Zifeng, CHEN Guomei, XU Laijun, BAI Yawen, LI Qingzhong, ZHAO Yongwu. Effect of Different Oxidizers on Chemical Mechanical Polishing of 6H-SiC[J]. Journal of Mechanical Engineering, 2018, 54(19): 224-231.

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