This work is aimed at studying the feasibility of laser induced, high-speed, highly selective direct deposition of metals on substrates immersed in commercial electroplating solutions without masking procedures and external electric current.
A Q-Switch Nd/YAG pulsed laser system and excimer UV pulsed laser systems operating respectively at wavelength of 532nm and at 193 and 248nm, were used in conjunction with commercial basic potassium gold cyanide and acidic gold tetrachloride solutions. The substrates were semiconductors (silicon, gallium arsenide and silicon carbide), metallic (platinum) and polymeric (polyimide).
The morphology, structure, composition and properties of the gold deposits were examined by the SEM, TEM, X-ray, AES and ESCA techniques.
Deposits were found to consist of elemental gold with thickness range from a few hundred angstroms to several micrometers, depending primarily on laser energy density and on the number of pulses. Deposition occurred wherever band gap energies (plus surface barrier) were smaller than the laser photon energy; none was observed in reverse situations, as in the cases of Si3N4 and fused SiO2.
The deposits exhibited Schottky barrier contacts on silicon, silicon carbide and gallium arsenide.