Reactive pulsed laser deposition of high-k silicon dioxide and silicon oxynitride thin films for gate-dielectric applications

We have successfully developed two reactive pulsed laser deposition (PLD) processes for the growth of high-k SiO2 and SiOxNy thin films. At a KrF laser intensity of 3 X 10(8) W/cm(2), both SiO2 and SiOxNy films have been deposited by ablating a silicon target in a reactive gas atmosphere (O-2 and O-2/N-2 mixture, respectively) on both Si (100) and Pt-coated Si substrates. Two key issues are presented here, namely (i) the effect of the deposition temperature (T-d in the 20-450 degreesC range) and (ii) the effect of the N incorporation (in the 0.3-20 at. % concentration range) on the microstructure and electrical properties of PLD SiO2 and SiOxNy thin films, respectively. For the PLD-SiO2 films, 300 degreesC has been identified as the optimal deposition temperature that yields stoichiometric ([O]/[Si] approximate to 1.9), hydrogen-free films with a low local disorder, a highly dense microstructure and a dielectric constant (k) higher than that quoted for thermally grown SiO2. On the other hand, the PLD SiOxNy films containing 20 at. % of N have exhibited a dielectric constant as high as similar to7. A rather good agreement is obtained between the k values deduced from the Poole-Frenkel emission (PFE) model and those obtained from direct impedance measurements, confirming thereby that the PFE remains the predominant conduction mechanism in the PLD SiOxNy films. (C) 2002 American Vacuum Society.