超声振动条件下碳化硅抛光过程的分子动力学模拟

Molecular Dynamics Simulation of Polishing Process of Silicon Carbide Under Ultrasonic Vibration Conditions

为了深入探讨在超声振动条件下立方碳化硅化学机械抛光过程中原子层面的材料去除机制,利用分子动力学方法建立碳化硅原子模型,以分析超声振动对刻划加工过程中碳化硅的晶体结构、温度、法向力和切向力的影响规律,并分析了超声振动频率对化学机械抛光质量及材料去除率的影响.结果表明:在刻划加工过程中碳化硅的局部出现了非晶态变化;超声振动的引入将大幅降低磨粒所受平均切向力和平均法向力,从而有利于刻划加工的进行及其表面质量的提高;在给定的模拟参数条件下,80GHz的超声振动频率最有利于提高材料去除率和加工表面质量,即当振动频率超过一定值后,超声振动对材料去除率和表面质量的影响不大.

To deeply understand the material removal mechanisms at the atomic level in the process of chemical mechanical polishing(CMP)of silicon carbide(SiC)under ultrasonic vibration conditions,molecular dynamics(MD)method was employed to establish an atomic model of SiC scratched by a diamond abrasive,and the crystal structure,temperature,normal and tangential forces of SiC during the scratching process were investigated.The effects of ultrasonic vibration frequency on the scratched surface quality and material removal rate of SiC in the scratching process were also analyzed.Simulation results indicate that during the cutting process,amorphization appears in the local area of processed SiC surface.The introduction of ultrasonic vibration to the SiC scratching process can alleviate the average tangential force and the average normal force of the imposed abrasive,which is beneficial to the scratching process and the improvement of scratched surface quality.For the given simulation parameters,the best ultrasonic vibration frequency which can lead to a better polished surface quality and higher material removal rate is80 GHz,above which the surface quality and material removal rate are less affected by the ultrasonic vibration.