基于响应面法的CMP后清洗工艺优化实验

Optimization Experiment of Post-CMP Cleaning Process by Response Surface Method

在集成电路制造化学机械平坦化(CMP)制程中,后清洗工艺直接关系到晶圆表面缺陷、洁净度和表面粗糙度等关键工艺指标。而主流CMP后清洗过程中超洁净刷洗工艺至关重要,以新型国产CMP机台为基础,以半导体制造前道制程标准化二氧化硅衬底直径300 mm晶圆为测试对象,开展响应面优化实验,对CMP后清洗晶圆转速、清洗刷转速和清洗液体积流量等关键参数进行研究。结合刷洗工艺原理初步掌握了相关关键参数对洁净度及表面粗糙度的影响规律,得到满足工艺要求的最佳参数,即晶圆转速145~150 r/min、清洗刷转速200~215 r/min和清洗液体积流量20~50 mL/min,可稳定实现晶圆表面粒径为0.12μm的颗粒数少于15和表面粗糙度0.5 nm以下的CMP后清洗优化工艺。研究结果可指导后续实验设计,并进一步得到相关工艺条件下参数及工艺效果的预测模型。

In the chemical-mechanical planarization(CMP) process of integrated circuit manufacturing, the post-cleaning process is directly related to the wafer surface defect, cleanliness, surface roughness and other key process indexes. Ultra-clean brushing process is very important in the mainstream post-CMP cleaning process. Based on the new domestic CMP machine, the response surface optimization experiment was carried out on the semiconductor manufacturing front-end process standardized 300 mm diameter wafer with silica as the substrate to study key parameters, such as post-CMP cleaning wafer rotational speed, cleaning brush rotational speed and cleaning fluid volume flow. Combined with the principle of the brushing process, the influence law of related key parameters on the cleanliness and surface roughness was preliminarily mastered, and the optimum parameters were obtained to meet the process requirements. When the wafer rotational speed is 145-150 r/min, the rotational speed of cleaning brush is 200-215 r/min and the volume flow of cleaning fluid is 20-50 mL/min, the optimized post-CMP cleaning process of wafer surface with the number of wafer surface particles with 0.12 μm particle size less than 15 and surface roughness below 0.5 nm can be steadily achieved. The research results can guide the subsequent experimental design, and further obtain the prediction model of parameters and process effect under relevant technological conditions.