ON THE MECHANISM OF POLYIMIDE SURFACE ROUGHENING DUE TO ANISOTROPIC ETCHING WITH A BEAM OF FAST OXYGEN-ATOMS

Analytical electron microscopy is employed to study the structure of i ndividual elements of a ''fibrous'' relief formed on the surface of a polyimide film (Capton N) etched with a beam of fast (2-4 eV) oxygen a toms. At an integral flow of atoms equal to 10(20) atom/cm(2) the prot rusions formed on the surface are shown to be mushroom-shaped. They co nsist of a cylindrical ''stem'' 20-40 nm in diameter and 2 mu m high a nd a ''hat'' 30-50 nm in diameter. It is inferred that the oval partic les, ''hats'', at the protrusion top consist of amorphous diamond-like carbon which is more resistant to impact of fast oxygen atoms than po lyimide. Stem etching by oxygen atoms scattered in the fluffy fibrous layer is supposed to eventually lead to liberation of the diamond-like particles and their conversion into dust.