METAL-DEPOSITION INTO A POROUS SILICON LAYER BY IMMERSION PLATING - INFLUENCE OF HALOGEN IONS

Metal deposition into a porous silicon (PS) layer by immersion plating has been studied. Ag and Cu were found to deposit on PS, while Ni was found not to deposit. The dependence of the amount of Cu deposition o n Cu2+ concentration, halogen ion concentration, and immersion time wa s investigated using chelatometric titration. Copper deposition from h alide solutions exhibited an unusual behavior; the amount increased wi th increasing concentration, then decreased, and no copper deposited a t high concentration. This is because adsorption of chloride and bromi de ions inhibits the copper deposition process. We have also discussed the metal deposition mechanism on the basis of x-ray diffraction, Fou rier transform infrared spectroscopy, and x-ray photoelectron spectros copy measurements. They revealed that metal deposition occurred simult aneously with the oxidation of silicon to SiO2. Copper crystals 30-80 nm in diameter deposited on the oxidized PS surface rather than on the unoxidized PS surface. (C) 1998 American Institute of Physics.