A method of forming a conductor in a thin 
film structure on a 
semiconductor substrate includes forming high 
aspect ratio openings in a base layer having vertical side walls, depositing a 
dielectric barrier layer comprising a 
dielectric compound of a barrier 
metal on the surfaces of the high 
aspect ratio openings including the vertical side walls, depositing a 
metal barrier layer comprising the barrier 
metal on the first 
barrier layer, depositing a main conductor species seed layer on the metal barrier layer and depositing a main conductor layer. The method further includes annealing the main conductor layer by (a) directing light from an array of 
continuous wave lasers into a line of light extending at least partially across the thin 
film structure, and (b) translating the line of light relative to the thin 
film structure in a direction transverse to the line of light. The method of Claim 1 further comprising, prior to the annealing step, depositing an 
amorphous carbon optical absorber layer on the main conductor layer. The step of depositing an 
amorphous carbon optical absorber layer includes introducing a carbon-containing process gas into a reactor chamber containing the substrate in a 
process zone of the reactor, applying RF source power to an external reentrant conduit of the reactor to generate a reentrant toroidal RF 
plasma current passing through the 
process zone and applying a bias 
voltage to the substrate.