X-ray and vacuum ultraviolet imaging for electron cyclotron resonance processing plasmas

Abstract

Electron cyclotron resonance (ECR) plasma systems are currently being investigated for plasma etching and plasma enhanced chemical vapor deposition. ECR generates high charged-particle densities at lower operating pressures which permits a higher degree of directionality for plasma etching, but produces low-energy x rays and vacuum ultraviolet radiation (VUV). Both types of radiation may cause damage to the wafer being processed. To reduce or shield the radiation damage, one would need to determine the spectrum and locations where the radiation is produced. The regions of radiation production can be determined by the image obtained from a pinhole camera placed along and across the center line of the dc magnetic field. The location of x-ray production could be changed by altering the shape of the dc magnetic field. The results verify that x rays are produced whenever hot electrons that travel along magnetic field lines strike the chamber walls. Similar methods were used to image the VUV radiation. The images show that the VUV is produced over the entire bulk plasma in addition to locations of wall bremsstrahlung where the x rays were produced.