XPS investigation of aluminum and silicon surfaces nitrided by a distributed electron cyclotron resonance nitrogen plasma

Aluminum and silicon samples were nitrided by a distributed electron cyclotron resonance nitrogen plasma. The plasma conditions used for the treatment correspond to a maximum N-2' concentration in the sample position, determined by optical emission spectroscopy. The substrates were always polarized by a DC bias voltage at -120 V and were externally heated or not. Nitrided samples were characterized by X-ray photoelectron spectroscopy (XPS) after an exposure to ambient air. A depth profile of the treated substrates was achieved by AC etching sequences in the XPS spectrometer. When the samples are polarized and heated at 500 degreesC during the plasma treatment, the nitride layer (dense AIN or Si3N4 and diffusion layers) obtained on aluminum (similar to0.3 mum) is much thicker than on silicon (similar to 30 Angstrom). (C) 2001 Elsevier Science B.V. All rights reserved.