Fast ICCD imaging of KrF excimer laser induced titanium plasma plumes for silicon metallization

Pulsed laser deposition (PLD) is applied to grow titanium thin films on silicon substrates for wafer metallization. Dynamics of plasma during the thin film deposition is investigated by fast intensified charge coupled detector (ICCD) time integrated photography. Plasma images at different gate delays after laser irradiation are taken to study plasma size, distribution, expansion and interaction with the substrates. Plume flying and expansion speeds in the directions normal and parallel to target surface are calculated. Fast ICCD imaging shows that the plasma starts to fly and expand at speeds as high as 10 ⁶ cm/s and reduces gradually to zero with gate delay. The dependence of plume size and speeds on laser fluence, gate delay, target-to-substrate distance and chamber pressure is analyzed to optimize processing parameters for the thin film deposition.