CU CVD FROM COPPER(II) HEXAFLUOROACETYLACETONATE .2. LASER-ASSISTED SELECTIVE-AREA DEPOSITION

The laser-assisted chemical vapor deposition of copper onto thermal SiO2-overcoated Si wafers in a cold wall atmospheric pressure reactor, using Cu(hfa)(2) in Ar/H-2 (10%), or argon as carrier/diluent is discussed. The substrate was biased thermally at 130 degrees C in Ar/H-2 or 200 degrees C in Ar. A multiline (lambda = 488 to 514 nm) continuous wave 4 mu m focused spot diameter, 150 mW argon ion laser was used to heat the spot to a temperature at, or above, the required decomposition temperature, greater than or equal to 150 degrees C in Ar/H-2 and greater than or equal to 250 degrees C in Ar. The steady-state temperature on the SiO2 prior to the beginning of deposition was estimated using a modified Lax model, since there is no convenient way of measuring it experimentally. Under the conditions employed, a maximum copper spot growth rate of 0.12 mu m/min was obtained at 0.095 W laser power. The laser-assisted growth rates in the present system can be predicted within a factor of two from the kinetic model of Ehrlich and Tsao. An incubation time which varies inversely with power, and with the composition of the carrier gas was observed on SiO2, due to the low absorption of the incident energy in the SiO2 at the small laser power used. Auger electron spectroscopy, of the copper deposits has shown small levels of carbon and oxygen. It is possible that the temperature at the center of the beam spot is greater than 400 degrees C after copper begins to nucleate, and that the organic ligands undergo some fragmentation, or that some degree of oxidation and carbonaceous contamination occurs upon exposure to air when specimens are removed from the reactor. Using the described deposition methods, it should be possible to effect repair of broken copper lines on a microelectronic package in a minute or two.