Cl2/Ar感应耦合等离子体刻蚀Si工艺研究

摘要

采用Cl2/Ar感应耦合等离子体（ICP）对单晶硅进行了刻蚀，工艺中用光刻胶作掩膜。研究了气体组分、ICP功率和RF功率等工艺参数对硅刻蚀速率和硅与光刻胶刻蚀选择比的影响，同时还研究了不同工艺条件对侧壁形貌的影响。结果表明，由于物理刻蚀机制和化学刻蚀机制的相对强度受到混合气体中Cl2和Ar比例的影响，硅刻蚀速率随着Ar组分的增加而降低，同时选择比也随之降低。硅刻蚀速率随着ICP功率的增大先增大继而减小，选择比则成上升趋势。硅刻蚀速率和选择比均随RF功率的增大单调增大。在Cl2/Ar混合气体的刻蚀过程中，离子辅助溅射是决定硅刻蚀效果的重要因素。同时，文中还研究分析了刻蚀工艺对于微槽效应和刻蚀侧壁形貌的影响，结果表明，通过提高ICP功率可以有效减小微槽和平滑侧壁。进一步研究了SiO2掩膜下，压强改变对于硅刻蚀形貌的影响，发现通过降低压强，可以明显地抑制杂草的产生。%This paper introduces the inductively mask by the C12/Ar mixed-gas process. The effects coupled plasma （ICP） etching of silicon with photoresist （PR） of process parameters such as gas combination, ICP and RF power on the etch rate of Si and the selectivity of Si/photoresist and on the sidewall profile are investigated. It is found that the ratio of C12 to Ar flow rate significantly affects the etch rate, due to the trade-off between physical and chemical component of etching. The etch rate of Si decreases with the increase of percent of Ar, and the selectivity has the same trend. With the increase of ICP power, the etch rate of Si increases first and then decreases, and the selectivity increases with the ICP power. The etch rate and selectivity increases monotonously with RF power. Be- sides, ion-induced sputtering is an important factor in the C1JAr mixed-gas etching. In the etching process, Micro- trenching and sidewall surfaces can be smoothed by rising the ICP power. Besides, we study the profiles of Si with SiO2 mask under different pressures, and find that plasma grass will be controlled at a low pressure.