Reactive Ion Etching in VHF Diode Reactors

摘要：Murnick CTS-9419440的主要目的是确定甚高频二极管反应器在CF4等离子体中反应离子蚀刻硅的有效性。PI指出，至少在非晶硅沉积的情况下，在甚高频（30-300 MHz）频率下而不是在标准的13.56 MHz频率下操作，可以提高沉积速率，减少损伤，提高薄膜均匀性。PI预计，与标准的100 KHz-13.56 MHz范围相比，VHF频段的放电物理特性会有很大不同，并从他们之前的工作结果中提供了一些证据。他们指出甚高频操作尚未应用于刻蚀，并提出了在CF4等离子体中刻蚀硅的刻蚀速率、均匀性、各向异性和损伤的测定方法。频率范围为13.56至135 MHz，压力范围为1至50 mTorr，应用电压范围很广。如果可能的话，将确定优化蚀刻过程某些方面的等离子体条件。对蚀刻材料的诊断将与位于蒙茅斯堡的陆军研究实验室合作进行，使用标准的表面技术，包括扫描电镜、轮廓测量学和透射电镜。ARL的微波干涉仪（目前借给罗格斯大学）也将用于测量绝对的、空间平均的等离子体密度。亚稳定氩族也将使用视线自吸收技术进行测量。PI还提议与科学研究协会的Meya Meyyappan博士合作，对实验等离子体进行建模。他希望为PI提供他目前的一维等离子体模拟代码的二维版本，并将协助建模工作，以便为蚀刻结果的解释提供支持。

Abstract Murnick CTS-9419440 The primary objective of the proposed work is to determine the effectiveness of a VHF diode reactor for reactive ion etching of silicon in CF4 plasmas. The PI's point out that operation at VHF ( 30-300 MHz) frequencies rather than at the standard 13.56 MHz, at least in the case of amorphous silicon deposition, can result in increased deposition rates, reduced damage, and increased film uniformity. The PI's expect the discharge physics to be quite different in the VHF regime as compared to the standard 100 KHz-13.56 MHz range and provide some evidence for this from results of their previous work. They point out that VHF operation has not as yet been applied to etching, and propose to determine etch rates, uniformity, anisotropy and damage for the etching of silicon in CF4 plasmas. Frequencies from 13.56 to 135 MHz, pressures from 1 to 50 mTorr, and a wide range of applied voltages will be employed. If possible, plasma conditions which optimize certain aspects of the etch process will be identified. Diagnostics on the etched materials will be carried out in collaboration with the Army Research Laboratory conveniently located at Fort Monmouth, using standard surface techniques including SEM, profilometry, and TEM. Use will also be made of ARL's microwave interferometer, currently on loan to Rutgers, to measure absolute, spatially averaged plasma densities. Meta-stable argon populations will also be measured using a line-of sight self-absorption technique. The PI's also propose to collaborate with Dr. Meya Meyyappan of Scientific Research Associates in the modeling of the experimental plasmas. He hopes to provide the PI's with a 2-D version of his current 1-D plasma simulation code and will assist in the modeling effort in order to provide support for the interpretation of the etching results.