In situ plasma monitoring of pulsed laser deposition of diamond-like carbon films

Pulsed laser deposition (PLD) is a dynamically unstable process, which can be controlled by in situ diagnostic methods. Recently, an optical spectrometer (OS) was used to monitor the plasma composition and a quartz crystal microbalance (QCM) was introduced to control the deposition rate. In the present studies, the development of PLD in situ control is continued by introducing an ion probe into the plasma and using the OS to measure the kinetic energy of carbon ions in diamond-like carbon (DLC) deposition. An original approach was used to read probe currents with 1024 sampling points during the time of flight of ablated species from the target to the substrate. The method was applied to the deposition of DLC, comparing the ablation of graphite and polycarbonate targets, using a 248 nm KrF wavelength. The correlation of probe currents with QCM and OS data is discussed and compared with results from electron energy loss spectroscopy and microindentation studies. Quantitative dependences between the laser fluence and kinetic energy of carbon species, deposition rate and ion current are found. A possible method for in situ control of DLC film growth with required properties is proposed based on the combination of these studies and existing models of DLC deposition and PLD dynamic control.