乙二胺在硅化学机械抛光中的作用机制

利用胶体二氧化硅在胺的辅助下对硅片进行抛光是微电子工业中的一种典型制造工艺,其动力学过程仍然不清楚。研究了在硅抛光中加入不同浓度乙二胺(EDA)对抛光速率的影响,结果表明EDA浓度提高时,硅的抛光速率逐渐增大,并且在质量分数5%时增加74.5%。为了揭示其中的作用机理,对EDA和Si在水中的电离性质作了分析,对硅片表面在EDA碱性溶液中的接触角以及Si经过EDA溶液浸泡后的表面作了X射线光电子能谱(XPS)测试,进一步采用基于反应力场的分子动力学模拟了动态反应过程。分析表明EDA和硅片表面不仅有强烈的库仑吸附作用,且Si和EDA通过Si-N进一步形成化学键,其中EDA中的N原子与硅表面原子能形成两种结构,使附近的Si-Si和Si-O键极化。基于这些测试,最终解释了硅在含有EDA碱性抛光液中的抛光动力学过程,此作用机制可为硅衬底加工的抛光液研制提供一定的技术指导。

Mechanism Study on Silicon CMP Using Ethylenediamine

Silicon polishing using colloidal silica with assistance of amine is a typical manufacturing process in micro electronics industry,which kinetic process is still unclear. The effect of different concentrations of ethylenediamine (EDA) on the polishing rate was studied. The results showed that the polishing rate of silicon increased gradually with the increase of EDA concentration, and by 74. 5% at 5%. In order to reveal the mechanism of the action, the ionization properties of EDA and Si in water were analyzed, the contact angle of the silicon surface in EDA alkaline solution and the X-ray photoelectron spectroscopy (XPS) of Si soaked in EDA solution were tested, the dynamic reaction process was also simulated by the molecular dynamic simulation based on reaction force field. The results show that the surface of EDA and silicon wafer not only has strong Coulomb adsorption, but also Si and EDA form chemical bonds through Si-N atoms in EDA, which polarizes the nearby Si-Si and Si-O bonds. Based on these tests, the polishing dynamics of silicon in the alkaline polishing slurry containing EDA is explained. The mechanism could provide some technical guidance for the development of polishing slurry for silicon substrate processing.