采用PSG牺牲层的空腔结构平坦化工艺  

Planarization Process of Cavity Structure Using PSG Sacrificial Layer

作　　者：冯志博 刘启迪 倪烨 董晟园 张智欣 于海洋 孟腾飞 Feng Zhibo;Liu Qidi;Ni Ye;Dong Shengyuan;Zhang Zhixin;Yu Haiyang;Meng Tengfei(Beijing Aerospace Microelectronics Technology Co.,Ltd.,Beijing 100854,China)

机构地区：[1]北京航天微电科技有限公司,北京100854

出　　处：《微纳电子技术》2024年第5期141-148,共8页Micronanoelectronic Technology

摘　　要：对基于微机电系统(MEMS)采用磷硅玻璃(PSG)牺牲层的空腔结构平坦化工艺进行了研究。探讨了抛光液体积流量、抛光压力、抛光液种类对牺牲层抛光速率、均匀性和硅槽台阶高度的影响,并对膜层表面质量进行分析和表征。结果表明:二氧化硅类抛光液体积流量控制在120 mL/min,此时抛光速率最高且有利于节约成本;优化了抛光压力工艺参数,当晶圆背压和保持环压力之比为0.76,即当晶圆背压为320 g/cm^(3),保持环压力为420 g/cm^(3)时,可有效地改善牺牲层薄膜的均匀性;引入二氧化铈类抛光液,采用两步抛光工艺,即粗抛时采用二氧化硅类抛光液,精抛时采用二氧化铈类抛光液,可以得到较为理想的台阶高度差;最后将化学机械抛光(CMP)后牺牲层表面形貌进行表征,得到较为优异的牺牲层薄膜质量。The planarization process of cavity structures using sacrificial layers of phosphorus silicon glass(PSG)based on microelectromechanical systems(MEMS)was investigated.The effects of slurry volume flow,polishing pressure and slurry type on removal rate,uniformity and silicon groove step height of sacrificial layer were discussed,and the surface quality of the film layer was analyzed and characterized.The results show that when the volume flow of SiO2 slurry is controlled at 120 mL/min,the removal rate is the highest and the cost is saved.The polishing pressure parameters are optimized.When the ratio of back pressure to retaining ring pressure of the wafer is 0.76,that is,when the back pressure of the wafer is 320 g/cm^(3) and the retaining ring pressure is 420 g/cm^(3),the uniformity of sacrificial layer film can be effectively improved.The ideal step height difference can be obtained by introducing CeO_(2) slurry and adopting two-step polishing process,namely,SiO2 slurry is used in rough polishing and CeO_(2) slurry is used in fine polishing.Finally,the surface morphology of sacrificial layer after chemical mechanical polishing(CMP)was characterized,and the excellent quality of the sacrificial layer thin film was obtained.

关 键 词：微机电系统(MEMS) 空腔结构 牺牲层 平坦化 台阶高度差 表面粗糙度 

分 类 号：TN305.2[电子电信—物理电子学] TQ421.4[化学工程]