催化剂浓度对6H-SiC晶片Si面化学机械抛光性能的影响

滕康, 陈国美, 倪自丰, 钱善华, 白亚雯

表面技术 ›› 2019, Vol. 48 ›› Issue (3) : 291-296.

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表面技术 ›› 2019, Vol. 48 ›› Issue (3) : 291-296. DOI: 10.16490/j.cnki.issn.1001-3660.2019.03.039
表面质量控制及检测

催化剂浓度对6H-SiC晶片Si面化学机械抛光性能的影响

  • 滕康1, 倪自丰1, 钱善华1, 陈国美2, 白亚雯3
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Effect of Catalyst Concentration on Chemical Mechanical Polishing Performance of Si Surface of 6H-SiC Wafer

  • TENG Kang1, NI Zi-feng1, QIAN Shan-hua1, CHEN Guo-mei2, BAI Ya-wen3
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摘要

目的 提高6H-SiC晶片Si面化学机械抛光(CMP)的材料去除率(MRR),改善其抛光表面质量。方法 使用含有不同Cu2+浓度和甘氨酸形成的配合物作为催化剂、H2O2作为氧化剂的抛光液,对6H-SiC晶片Si面进行CMP。使用精密天平称量SiC晶片抛光前后的质量,计算其MRR。使用AFM观测SiC晶圆表面,测其表面粗糙度(Ra)。使用Zeta电位仪测量在不同Cu2+浓度下纳米氧化硅磨粒的Zeta电势和粒径分布。使用摩擦磨损试验机测量不同Cu2+浓度时SiC晶圆的摩擦系数。对比不同压力和转速在CMP中对SiC的MRR和Ra的影响。结果 随着Cu2+浓度的增大,MRR先增大后减小,在Cu2+体积浓度为300 μmol/L时,MRR有最大值,为82 nm/h,此时,Ra为0.156 nm;相比之下,不加入Cu2+-甘氨酸配合物的MRR为62 nm/h,Ra为0.280 nm。同时,随着Cu2+浓度的增大,一方面,溶液中磨粒的Zeta电势绝对值不断减小,但高于不加入Cu2+-甘氨酸配合物时的Zeta电势绝对值;另一方面,其平均粒径逐渐增大,但低于不加入Cu2+-甘氨酸配合物时的平均粒径(104.0 nm)。另外,随着Cu2+浓度的增大,SiC晶圆的摩擦系数先增大后减小,在300 μmol/L时达到最大,为0.6137。最后,随着压力的增大,MRR不断增加,但压力过大,使得Ra增大。随着抛光盘转速的增大,MRR先增大后减小,Ra无明显变化,在120 r/min时,MRR有最大值,为96 nm/h,Ra为0.161 nm。结论 Cu2+-甘氨酸配合物作为催化剂能够加快SiC化学机械抛光中的化学氧化速率,从而提高MRR,并且能够提高抛光液分散稳定性,改善SiC晶圆表面质量。另外,增大抛光压力可以增强机械磨削作用,提高MRR,但压力过大,会损伤晶片表面。抛光盘转速的增大也可以提高MRR,但其过大则会使抛光液外溅,降低化学作用,导致MRR降低。

Abstract

The work aims to improve the material removal rate (MRR) and the surface quality of the Si-face 6H-SiC wafer by chemical mechanical polishing (CMP). CMP was performed on the Si-face of 6H-SiC wafer with a polishing slurry including the different concentrations of Cu2+ and glycine as catalysts and the hydrogen peroxide (H2O2) as an oxidant. The SiC wafer was weighed by a precision balance to calculate the MRR before and after polishing. AFM was used to observe the surface of the SiC wafer and the surface roughness (Ra) was measured. The Zeta potential and particle size distribution of the nano-silica abrasive particles were measured by a Zeta potential meter at different concentrations of Cu2+. The friction and wear tester was used to measure the friction coefficient of SiC wafer with different concentrations of Cu2+. The effects of different pressures and rotational speeds on the MRR and Ra of SiC during CMP were compared. With the increase of Cu2+ concentrations, the MRR increased firstly and then decreased. When the Cu2+ concentration was 300 μmol/L, the MRR had a maximum of 82 nm/h, and in this case, the Ra was 0.156 nm. In contrast, the MRR was 62 nm/h and the Ra was 0.280 nm without the addition of the Cu2+-glycine complex. At the same time, with the increase of the Cu2+ concentrations, on the one hand, the absolute values of the zeta potential of the abrasive particles in the slurry decreased, but was still higher than the absolute value of the zeta potential without the addition of the Cu2+-glycine complex; on the other hand, the average particle diameters of the abrasive particles gradually increased, but was still smaller than the average particle diameters (104.0 nm) without the addition of the Cu2+-glycine complex. In addition, as the Cu2+ concentration increased, the friction coefficient of the SiC wafer firstly increased and then decreased, reaching a maximum of 0.6137 at 300 μmol/L. Finally, as the pressure increased, the MRR increased gradually, but the Ra increased when the pressure was too high. With the increase of the polishing plate speed, the MRR increased firstly and then decreased, but there was no significant changes in the Ra. At the speed of 120 r/min, the MRR had a maximum of 96 nm/h with the Ra of 0.161 nm. As a catalyst, the Cu2+-glycine complex can accelerate the chemical oxidation rate in the CMP of SiC to increase the MRR, and can improve the dispersion stability of the slurry to make the surface quality of the SiC wafer better. In addition, increasing the polishing pressure can enhance the mechanical grinding effect and magnify the MRR, but if the pressure is too high, the wafer surface will be damaged. An increase in the rotational speed of the polishing plate can also increase the MRR, but if the speed is too high, the polishing solution will splash out, lowering the chemical effect and resulting in a decrease of the MRR.

关键词

碳化硅;化学机械抛光;催化剂;材料去除率;表面粗糙度;粒径分布

Key words

silicon carbide; chemical mechanical polishing; catalyst; material removal rate; surface roughness; particle size distribution

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滕康, 陈国美, 倪自丰, 钱善华, 白亚雯. 催化剂浓度对6H-SiC晶片Si面化学机械抛光性能的影响[J]. 表面技术. 2019, 48(3): 291-296
TENG Kang, CHEN Guo-mei, NI Zi-feng, QIAN Shan-hua, BAI Ya-wen. Effect of Catalyst Concentration on Chemical Mechanical Polishing Performance of Si Surface of 6H-SiC Wafer[J]. Surface Technology. 2019, 48(3): 291-296

基金

国家自然科学基金(51305166)

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