Low resistivity LCVD direct write Cu conductor lines for IC customisation

Laser chemical vapor deposition (LCVD) of low resistivity copper from Cu(hfac)tmvs (copper(I)-hexafluoroacetylacetonate trimethylvinylsilane) is presented. The deposition was performed on Si3N4 and SiO2 passivated ICs. The deposition of Cu lines was carried out by a focused Ar+ laser beam. The deposition speed and the laser power were varied in the range of 24 to 400 mu m/s and 40 to 1200 mW, respectively. The precursor gas partial pressure was 0.3 mbar buffered in 10 mbar He or H-2. The morphology of the deposited lines was investigated by AFM, optical microscopy and LIMA. The LIMA analysis showed the deposited copper surface was contaminated but the contamination level decreased when the layer was depth profiled. The electrical resistivity was found to be 3.7 mu Omega cm as determined by four point probe measurement. The effect of the laser beam focus location on the substrate surface is described. Low resistivity laser direct-write Cu lines were utilised in specific IC customisation cases.