Pulsed liquid-injection MOCVD of high-K oxides for advanced semiconductor technologies
Résumé
HfO2 and SrTiO3 films were grown on silicon by liq. injection metal org. chem. vapor deposition. The microstructure and structure of the films were characterized by X-ray and electron diffraction, X-ray reflectometry, IR spectroscopy, and microscopy techniques. In both cases, we emphasized the role of precursors in the resulting compn. and microstructure of the films. Dense films of HfO2, either amorphous or cryst. depending on the deposition temp., were synthesized using Hf(OtBu)2(mmp)2 precursor. Permittivity values of 14-19 were obtained, consistent with the monoclinic structure detd. from X-ray diffraction. Optimized films exhibit breakdown field of 6 MV cm-1 and leakage current densities as low as 10-8 A cm-2 at 1 V. Polycryst. SrTiO3 films were grown using either a mixt. of precursors or a heterometallic precursor. The heterometallic precursor provides some advantages such as a lowering of the crystn. temp. of the perovskite-type phase and a redn. of carbonate impurities at low temps. It also allows to keep the films compn. const. over a wide temp. range (550 - 750°). The films are highly textured with [0 0 1]SrTiO3 parallel to [0 0 1]Si. The permittivity depends strongly on the films thickness (.vepsiln.r .apprx. 30 for 10 nm and .vepsiln.r .apprx. 100 for 100 nm). An equivalent oxide thickness of 1.36 nm (for phys. thickness of 15.0 nm) was obtained for optimized SrTiO3 film, with a leakage c.d. of 10-2 A cm-2 at 1 V.
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