基于光助芬顿反应的碳化硅化学机械抛光工艺优化

目的 高效快速获得紫外光辅助作用下碳化硅(SiC)化学机械抛光(Chemical mechanical polishing, CMP)的最佳加工参数。方法 根据化学作用与机械作用相平衡时达到最佳抛光条件的理论，通过电化学测试的方法探究抛光液pH值、过氧化氢(Hydrogen peroxide, H2O2)浓度、Fe²⁺浓度、紫外光功率等对基体表面氧化膜形成速率(化学作用)的影响;在最大氧化膜形成速率条件下，以材料去除率(Material removal rate, MRR)和表面粗糙度(Average roughness, Ra)为指标，通过调节抛光压力、抛光盘转速、抛光液流量等工艺参数，探究工艺参数对碳化硅加工过程中氧化膜去除速率(机械作用)的作用规律，寻求机械作用与化学作用的平衡点，获取紫外光辅助作用下SiC CMP的最佳工艺参数。结果 在pH值为3、H2O2的质量分数为4%、Fe²⁺浓度为0.4 mmol/L、紫外光功率为32 W时，化学作用达到最大值。在最大化学作用条件下，抛光压力、抛光盘转速、抛光液流量分别为38.68 kPa、120 r/min、90 mL/min时，化学作用与机械作用最接近于平衡点，此时材料去除率为92 nm/h，表面粗糙度的最低值为0.158 nm。结论 根据研究结果，电化学测试可以作为探究晶片表面氧化速率较高时所需加工参数的有效手段，进一步调节工艺参数，使化学作用速率与机械去除速率相匹配，高效地获得了材料去除率和表面质量较高的晶片。

#$NPOptimization of Chemical Mechanical Polishing Process of SiC Based on Photo-Fenton Reaction

In order to obtain optimal processing parameters of UV-assisted SiC chemical mechanical polishing quickly, according to the theory of optimum polishing condition when chemical action and mechanical action are in equilibrium, the effects of pH value of polishing solution, the concentrate of hydrogen peroxide (H2O2), concentration of Fe2+ and UV power on the formation rate of oxidation film on the substrate surface (chemical action) are explored by electrochemical test method; Under the condition of maximum oxide film formation rate, the material removal rate (MRR) and surface roughness (Average roughness, Ra) were used as indicators to investigate the effect of process parameters on the oxide film removal rate (mechanical action) during the processing of SiC by adjusting the process parameters such as polishing pressure, polishing disc speed and polishing fluid flow rate, and to seek the balance point of mechanical and chemical action to obtain the optimal process parameters of SiC CMP under the action of UV light. The results reveal that the chemical action reached its maximum when the pH value is 3, the mass fraction of H2O2 is 4%, the concentration of Fe2+ is 0.4 mmol/L and the UV power is 32 W. Under the condition of maximum chemical action, chemical action and mechanical action are closest to the equilibrium point when the polishing pressure, polishing disc speed and polishing fluid are 38.68 kPa, 120 r/min, 90 mL/min respectively, at which the MRR of 92 nm/h and the lowest Ra of 0.158 nm can be obtained. Based on the results of the study, electrochemical testing can be used as an effective means to explore the processing parameters required for the faster rate of oxide film formation on the wafer surface and further adjust the process parameters to match the chemical action rate with the mechanical removal rate to efficiently obtain high material removal rates and surface quality.