复合磨料的制备及其对层间介质CMP性能的影响

Preparation of the Composite Abrasive and Its Effect on CMP Performances of Interlayer Dielectric

以SiO_(2)为内核、CeO_(2)为外壳制备出了核壳结构复合磨料,用以提升集成电路层间介质的去除速率及表面一致性。采用扫描电子显微镜(SEM)观察复合磨料的表面形貌,利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)和X射线光电子能谱仪(XPS)分析复合磨料的表面物相结构及化学键组成。研究结果表明,所制备的复合磨料呈现出“荔枝”形,平均粒径为70~90 nm,CeO_(2)粒子主要以Si—O—Ce键与SiO_(2)内核结合。将所制备的复合磨料配置成抛光液进行层间介质化学机械抛光(CMP)实验。实验结果表明,Zeta电位随着pH值的降低而升高,当pH值约为6.8时达到复合磨料的等电点。当pH值为3时,层间介质去除速率达到最大,为481.6 nm/min。此外,研究发现去除速率还与摩擦力和温度有关,CMP后的SiO_(2)晶圆均方根表面粗糙度为0.287 nm。

The composite abrasive with a core-shell structure,in which SiO_(2) as the core and CeO_(2) as the shell,was prepared to improve the removal rate and surface uniformity of interlayer dielectric in inte-grated circuits.The surface morphology of the composite abrasive was observed by scanning electron microscope(SEM).The surface phase structure and chemical bond composition of the composite abrasive were analyzed by X-ray diffractometer(XRD),Fourier transform infrared spectrometer(FTIR)and X-ray photoelectron spectrometer(XPS).The research results show that the prepared composite abrasive exhibits a“lychee”shape with an average particle size of 70-90 nm,and CeO_(2) particles mainly combines with SiO_(2) core by Si—O—Ce bond.The prepared composite abrasive was configured into a poli-shing solution for chemical mechanical polishing(CMP)experiments of interlayer dielectric.The experi-mental results show that the Zeta potential increases with the decrease of pH value.When the pH value is about 6.8,the isoelectric point of the composite abrasive is reached.When the pH value is 3,the removal rate of interlayer dielectric reaches the fastest(481.6 nm/min).In addition,it is found that the removal rate is also influenced by friction and temperature.The root mean square surface roughness of SiO_(2) wafers after CMP is 0.287 nm.