Laser writing of high purity gold tracks

Gold tracks have been deposited on thermally oxidised silicon wafers by pyrolitic decomposition of gaseous methyl(triethylphosphine) gold (I), using focused 514 nm radiation from an argon ion laser. The precursor, AuMe(Et₃P), is a white crystalline solid with a room temperature vapour pressure of a few mTorr and is one of a series of compounds being evaluated for laser deposition. Tracks were deposited at speeds from 4.5 to 35 µm s^-1 with a focused spot size of about 12 µm. LIMA, SIMS and EDAX were used to analyse the chemical composition of the tracks; the purity of better than 98% is consistent with the low value of room temperature resistivity (4.2 µO cm, compared with approximately 2 µO cm for bulk gold). Stylus profilometry and SEM analysis showed the lines to have an almost rectangular cross section suggesting that deposition is more rapid on the gold surface than on the SiO₂ substrate. © 1989.