RIE工艺参数对4H-SiC刻蚀速率和表面粗糙度的影响

Effects of Reactive Ion Etching Parameters on Etching Rate and Surface Roughness of 4H-SiC

基于4H-SiC材料的微机电系统(MEMS)器件(如压力传感器、微波功率半导体器件等)在制造过程中,需要利用干法刻蚀技术对4H-SiC材料进行微加工。增加刻蚀速率可以提高加工效率,但是调节刻蚀工艺参数在改变4H-SiC材料刻蚀速率的同时,也会对刻蚀表面粗糙度产生影响,进而影响器件的性能。为了提高SiC材料的刻蚀速率并降低刻蚀表面粗糙度,满足4H-SiC MEMS器件研制的需求,本文通过优化光刻工艺参数(曝光模式、曝光时间、显影时间)获得了良好的光刻图形形貌,改善了刻蚀掩模的剥离效果。实验中采用SF_(6)和O_(2)作为刻蚀气体,镍作为刻蚀掩模,分析了4H-SiC反应离子刻蚀工艺参数(刻蚀气体含量、腔体压强、射频功率)对4H-SiC刻蚀速率和表面粗糙度的影响。实验结果表明,通过优化干法刻蚀工艺参数可以获得原子级平整的刻蚀表面。当SF_(6)的流量为330 mL/min,O_(2)流量为30 mL/min,腔体压强为4 Pa,射频功率为300 W时,4H-SiC材料的刻蚀速率可达到292.3 nm/min,表面均方根粗糙度为0.56 nm。采用优化的刻蚀工艺参数可以实现4H-SiC材料的高速率、高表面质量加工。

Dry etching is required to microfabricate 4H-SiC-based microelectromechanical system(MEMS)devices,such as pressure sensors and microwave power semiconductor devices.The processing efficiency can be boosted by improving the etching rate.However,adjusting the etching rate of 4H-SiC by manipulating etching process parameters not only changes the etched surface roughness,but also impacts the surface roughness of the etched surface.To achieve excellent pattern morphology and improve the etching mask lift-off quality while simultaneously improving the etching rate and reducing the surface roughness need of 4H-SiC,we optimized the photolithography process parameters,including exposure mode,exposure time,and development time,to meet the development need of 4H-SiC MEMS devices.We investigated the effects of etching process parameters(such as etching gas content,chamber pressure,and radio-frequency power)on etching rate and surface roughness in reactive ion etching(RIE)with SF_(6) and O_(2) as etching gas and Ni as an etching mask.The results show that a flat atomic surface can be achieved by optimizing etching process parameters.The etching rate of 4H-SiC is 292.3 nm/min and root-mean-square(RMS)roughness is 0.56 nm when the flow of SF_(6) and O_(2) is 330 and 30 mL/min,respectively,the chamber pressure is 4 Pa,and RF power is 300 W.High-quality etched surfaces with a high etching rate can be obtained using optimized etching process parameters.