基于分子量级的化学机械抛光界面动力学模型研究

考虑抛光液/芯片的相界面氧化剂浓度和芯片氧化薄膜缺陷对材料去除机理的影响,提出化学机械抛光(CMP)中材料去除机理的量级估算方法,应用化学动力学及传质学等理论估算氧化薄膜的扩散深度量级和生成速率,采用纳米压痕仪模拟单个磨粒在芯片表面的压痕作用,应用线性回归方法分析载荷70 nN下,磨粒压入芯片的深度量级为10-11 m.结合模型估算,证实了CMP材料去除机理为单分子层去除机理.结果表明,减小氧化膜厚度可以提高材料去除率,估算结果与他人试验结果相吻合.为进一步研究CMP单分子层材料去除机理提供了理论依据.

An Order-of-magnitude Calculation of Material Removal Mechanism in Chemical-mechanical Polishing at Molecular Scale

Presents a sequence of order-of-magnitude calculations based on the concepts of chemical kinetics and transport phenomena during the chemical mechanical polishing(CMP) process.The growth rate and diffusion thickness of the oxide layer were quantitatively evaluated in the magnitude analysis.The effects of the oxidizer concentration in the slurry at the wafer surface in addition to the diffusion coefficient under the defect condition were also addressed.In addition,the indentation depth of a single particle into the wafer surface was investigated using Ubi Scanning Quasistatic Nano-indentation with 70 nN force.The indentation depth was of an order of 10-11 m determined on the basis of the linear regression mechanism.The combined calculations and experimental results indicate that the CMP material was removed at the molecular scale.The results supported by published experimental data show that declining the oxide layer thickness will increase the material removal rate for advanced CMP process.This study lends further credence to the molecular-scale mechanism for the CMP material removal,as well as its underlying theoretical foundation.