XPS studies on aluminum ions modified polyimide with the PIII technique

Abstract

Polyimide samples modified by aluminum (Al) ions produced by filtered cathodic vacuum arc (FCVA) with plasma immersion ion implantation (PIII) technique, under ambient argon and oxygen gases (flow rate Ar:O2=2:1) were investigated by x-ray photoelectron spectroscopy (XPS). The working pressure was about 8×10−4 Torr and the plasma density was estimated to be 109 ions∕cm3. The applied bias voltages were varied from 5 to 12.5 kV but with fixed frequency at 900 Hz and duty time of 15μs. For 1 min process time, C 1s and O 1s spectra for modified samples clearly indicated that the carbonyl group (C=O) was largely destroyed by incident Al ions while Al 2p spectra suggested Al atoms remain inside polyimide matrices in the form of C-O-Al complexes. For a 5 min process time, when the ion fluence became large, both C 1s and O 1s spectra suggested a structure of “aluminum oxide-mixed layer-polyimide” and Al 2p spectra confirmed that most Al atoms were bonded to oxygen atoms on the top surface. These XPS results revealed the chemical bonds between implanted and deposited Al ions and polyimide matrix by using the PIII technique. The structural information can also be suggested. Furthermore in this paper, some discussions with the theoretical [the stopping and range of ions in matter (SRIM)] simulation were also mentioned in order to explore the effectiveness of Al ions irradiation on polyimide.