BIT作为缓蚀剂在铜互连阻挡层CMP的应用

Application of BIT as the Corrosion Inhibitor in CMP of Copper Interconnect Barrier Layer

化学机械平坦化(CMP)过程中极易在铜表面产生碟形坑、腐蚀坑等缺陷。为了解决这些问题,提出了将苯并异噻唑啉酮(BIT)作为CMP抛光液中的表面抑制剂,研究不同质量分数的BIT在Cu CMP过程对Cu的去除速率、SiO2介质对Cu的选择性及抛光后表面形貌的影响。研究结果表明,随着BIT质量分数的增加,SiO2的去除速率基本不变,Cu的去除速率由31.6 nm·min^-1降到21.0 nm·min^-1,碟形坑深度由110 nm降到40 nm,腐蚀坑深度由85 nm降到35 nm。扫描电子显微镜(SEM)测试结果表明,Cu表面低缺陷,无明显有机物沾污。傅里叶变换红外光谱(FTIR)测试结果表明,BIT能够吸附在Cu表面,生成一层钝化膜,从而抑制了Cu的腐蚀,降低Cu的抛光速率。

In the process of chemical mechanical planarization(CMP), the defects, such as dishing pits and erosion pits are easily generated on the Cu surface. In order to solve these problems, the benzoisothiazolinone(BIT) used as a surface inhibitor in the CMP polishing slurry was proposed. During the Cu CMP process, the effects of the BIT with different mass fraction on the removal rate of Cu, the selectivity of SiO2 to Cu and the surface morphology after polishing were studied. The study results show that with the increase of the BIT mass fraction the removal rate of SiO2 remains almost the same, the removal rate of Cu is from 31.6 nm·min^-1 to 21.0 nm·min^-1, the depth of the dishing pit is from 110 nm to 40 nm and the depth of the erosion pit is from 85 nm to 35 nm. Scanning electron microscope(SEM) test results show that the Cu surface has low defects and no obvious organic contamination. Fourier transform infrared spectrometer(FTIR) test results prove that BIT can be adsorbed on the Cu surface, forming a passivation film, inhibiting the corrosion of Cu and reducing the polishing rate of Cu.