Process control and pulsed laser deposition of materials

Pulsed-laser deposition (PLD) is a very powerful and rapid deposition technique, which can produce exceptional-quality thin films. Although PLD has tremendous versatility and potential, PLD capabilities are still constrained by a lack of process control. At the Air Force Research Laboratory on-site at Wright-Patterson AFB, we are developing in-situ/real-time control methodologies for PLD and other thin-film deposition processes. We have identified appropriate sensors for closed-loop feedback control and utilized them with YBa2Cu3O7-x, (YBCO) to identify critical process control parameters. Control instrumentation has recently been improved by the addition of moveable fixed-position plume-emission sensors. The reproducibility of YBCO film quality increased significantly when process control was applied to PLD processing. PLD process control techniques were applied during simulated and actual BSTO depositions. A comparison of deposition control with the controlling sensor at different distances from the substrate heater position is discussed. Further process refinement using Lime-resolved spectral components of the PLD plume on subsequent film quality is also discussed.