AVS 59th Annual International Symposium and Exhibition
    Thin Film Thursday Sessions
       Session TF+AS+SS-ThA

Paper TF+AS+SS-ThA10
Optical and Structural Properties of Hafnium Oxide Thin Films Prepared Using Different Deposition Techniques

Thursday, November 1, 2012, 5:00 pm, Room 11

Session: Thin Films: Growth and Characterization-III
Presenter: L. Sun, Air Force Research Laboratory
Authors: L. Sun, Air Force Research Laboratory
N.R. Murphy, Air Force Research Laboratory
J.T. Grant, Air Force Research Laboratory
J.G. Jones, Air Force Research Laboratory
R. Jakubiak, Air Force Research Laboratory
Correspondent: Click to Email
The high dielectric constant and optical transparency of hafnium oxide makes it a useful component in leading-edge integrated circuitry and optical coatings. The optical and structural properties of stoichiometric HfO2 films vary significantly depending on the deposition mechanism. We prepared 200 nm thick films of HfO2 on silicon (100) substrates derived from DC magnetron sputtering (DCMS), high power impulse magnetron sputtering (HiPIMS) and pulsed laser deposition (PLD). Analysis of x-ray diffraction data revealed that films deposited via PLD are amorphous, while those deposited using the magnetron sputtering methods had peaks at 2θ of 28.3°, 31.3°, 34.3° and 50.0° indicative of polycrystalline monoclinic HfO2. This is further supported by the FT-IR data collected in the far-IR regime where absorption bands at 258, 341, 410 and 514 cm-1 were present. AFM and SEM images indicate that the sputtered samples had rougher surface morphology and larger grain sizes than the PLD films where the surface was uniform and smooth (RMS surface roughness less than 0.1nm). The degree of surface roughness and grain size is inversely proportional to the refractive index. At 632 nm PLD films had an index of refraction of 2.10 while the index of the sputter coated films was 1.98, presumably due to presence of voids. The high refractive index and homogeneity of the PLD films indicate that they were highly packed without voids during growth. Additionally, the influence of the O2/Ar ratio, working pressure, HiPIMS pulse profile and duty cycle on optical properties, surface roughness, particle size and structural properties of the HfO2 thin films were characterized and evaluated.