Effect of time-varying axial magnetic field on high aspect ratio contact hole etching

Abstract

Time-varying axial magnetic field of approximately 10–15 G is added to an inductively coupled plasma. High aspect ratio deep-sub-micron contact holes in borophosphosilicate glass have been etched by C 4F 8/Ar plasma. In order to correlate etched profile with etching conditions, deposition of polymeric precursors in the etching process is monitored. By means of the appearance mass spectroscopy, the distributions of CF x + ions and CF x radicals are measured as a function of the frequency of axial magnetic field. The axial magnetic field is found to influence the densities of fluorocarbon ions (CF x +; x=1–3), F and CF x radicals. X-ray photoelectron spectroscopy shows that fluorocarbon polymer on oxide surface strongly varies with the frequency of axial magnetic field. 0.2 μm diameter contact holes with aspect ratio of 10 are successfully fabricated in this system.