X-RAY PHOTOELECTRON-SPECTROSCOPY ANALYSES OF METAL STACKS ETCHED IN CL-2 BCL3 HIGH-DENSITY PLASMAS/

We have used x-ray photoelectron spectroscopy to determine the chemica l elements present on the tops, sidewalls, and bottoms of submicron me tal features etched in a high density inductively coupled plasma sourc e using Cl-2/BCl3 gas mixtures. X-ray photoelectron spectroscopy analy ses have shown that aluminum oxide is deposited on all the surfaces of the features exposed to the plasma due to erosion of the alumina line r located in the source region. A chlorine rich carbon film is formed on the sidewalls and at the bottom of the aluminum features during the etching process, At the bottom of the features, chlorine species must diffuse through the carbon layer to etch aluminum whereas spontaneous reactions between chlorine and aluminum are blocked on the sides of t he features. On the sidewalls of the features, aluminum oxide species coming from the sputtering of the alumina liner are embedded in the ca rbon rich film as it grows, This sidewall passivation film enhances an isotropic etching by providing a thin protective layer against spontan eous etching reaction of chlorine with aluminum, (C) 1998 American Vac uum Society.