Effect of dopant type on immersion plating into porous silicon layer

Metal deposition into a porous silicon PS. layer prepared from n-type silicon by immersion plating was studied. The results were compared with those of p-type PS. Quantitative differences between p- and n-type PS were observed in the behaviors of the amount of metal deposition and Fourier transform infrared FTIR.spectra. Copper deposition was saturated by 2 min immersion in 1 M CuSO4 for p-type PS, whereas for n-type PS, the saturation was not attained by 20 min immersion in 1 M CuSO4. The intensities of absorptions due to SiH x decreased much faster for p-type PS than for n-type PS in FTIR spectra. PS prepared from p-type silicon is expected to have higher reactivity with aqueous solutions containing metal ion. This is probably due to the smaller crystallite size. However, PS samples formed on p- and n-type silicons showed the same behaviors qualitatively. Ag and Cu were found to deposit on PS, but Ni was found not to deposit. Adsorption of chloride and bromide ions on the PS surface inhibited the copper deposition process. Metal deposits chemically, simultaneously with the oxidation of silicon to SiO2. q1999 Elsevier Science B.V. All rights reserved.