STI CMP中SiO_(2)/CeO_(2)混合磨料对SiO_(2)介质层CMP性能的影响  

Influence of SiO_(2)/CeO_(2) Mixed Abrasive in STI CMP on the CMP Performance of SiO_(2) Dielectric Layer

作　　者：刘志 王辰伟 周建伟 张新颖 刘光耀 李越 闫妹 Liu Zhi;Wang Chenwei;Zhou Jianwei;Zhang Xinying;Liu Guangyao;Li Yue;Yan Mei(School of Electronic and Information Engineering,Hebei University of Technology,Tianjin 300130,China;Tianjin Key Laboratory of Electronic Materials and Devices,Tianjin 300130,China)

机构地区：[1]河北工业大学电子信息工程学院,天津300130 [2]天津市电子材料与器件重点实验室,天津300130

出　　处：《半导体技术》2022年第11期865-872,共8页Semiconductor Technology

摘　　要：为了在浅沟槽隔离(STI)化学机械平坦化(CMP)过程中提高对SiO_(2)介质层去除速率的同时保持晶圆表面一致性,研究了SiO_(2)/CeO_(2)混合磨料的协同作用以及对SiO_(2)介质层去除速率及一致性的影响。结果显示,相比于单一磨料,采用混合磨料能够兼顾介质去除速率和一致性。采用质量分数10%SiO_(2)(粒径为80 nm)与质量分数0.7%CeO_(2)磨料混合抛光后,对介质层的去除速率达到347 nm/min,片内非均匀性(WIWNU)为9.38%。通过场发射扫描电子显微镜(FESEM)观察颗粒状态发现,晶圆表面吸附大量的SiO_(2)颗粒会阻碍CeO_(2)磨料与晶圆表面接触,从而降低对晶圆中心的去除速率,使化学作用更均匀。通过将小粒径SiO_(2)磨料(40 nm)与CeO_(2)磨料混合,使介质层去除速率进一步提升至374 nm/min, WIWNU降低到8.83%,用原子力显微镜(AFM)表征抛光后晶圆的表面质量,小粒径SiO_(2)混合磨料抛光后的SiO_(2)介质层表面粗糙度为0.35 nm,在达到较高抛光性能的同时获得了较好的表面质量。To improve the removal rate of SiO_(2)dielectric layer during shallow trench isolation(STI) chemical mechanical planarization(CMP) while maintaining wafer surface uniformity, the synergistic effect of SiO_(2)/CeO_(2)mixed abrasive and its influence on the removal rate and uniformity of SiO_(2)dielectric layer were investigated.The results show that compared with single abrasive, the use of mixed abrasive can balance the dielectric removal rate and uniformity.After polishing with a mixed abrasive of 10% mass fraction SiO_(2)(particle size of 80 nm) and 0.7% mass fraction CeO_(2)abrasive, the removal rate of dielectric wafer reached 347 nm/min with a within wafer non-uniformity(WIWNU) of 9.38%.The observation of the particle state by field emission scanning electron microscopy(FESEM) reveals that the adsorbed large number of SiO_(2)particles on the wafer would prevent the CeO_(2)abrasive from contacting the wafer surface, thus reducing the removal rate of wafer center and making the chemical action more uniform.The removal rate of dielectric layer is further improved to 374 nm/min and the within wafer non-uniformity(WIWNU) is reduced to 8.83% by taking a mixture of small particle size SiO_(2)abrasive(40 nm) and CeO_(2)abrasive.Surface quality of polished wafer is characterized by atomic force microscopy(AFM),and the surface roughness of the SiO_(2)dielectric layer after polishing with small particle size SiO_(2)mixed abrasive is 0.35 nm, which achieves higher polish performance and better surface quality at the same time.

关 键 词：化学机械平坦化(CMP) 二氧化硅(SiO_(2)) 混合磨料 片内非均匀性(WIWNU) 协同作用 

分 类 号：TN305.2[电子电信—物理电子学]