The electrical properties of MIS capacitors with ALN gate dielectrics

We report on the characteristics of metal-insulator-semiconductor (MIS) cap acitors with aluminum nitride (AIN) as the dielectric material. Using react ive magnetron sputtering, we deposited layers of AIN on 1-10 Omega cm p-typ e (1 0 0) silicon wafers. The deposition rates were investigated as a funct ion of sputter pressure, power, gas composition, and substrate tempterature . On films deposited over a range of sputter parameters, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS) were performed indic ating that optimal deposition conditions for best crystal quality and stoic hiometry were a total pressure between 4 and 10 mT, a gas mixture of 85% ni trogen and 15% argon, and a substrate temperature approximate to 200 degree sC. The films had a weak microcrystalline structure with the c-axis prefere ntially orientated parallel to the substrate normal. MIS capacitors were fa bricated on silicon substrates with Ti/Au contacts. Current-voltage (IV) an d capacitance-voltage (CV) measurements revealed breakdown fields of 4-12 M V/cm. Depending on the thickness, leakage current densities were between 10 (-10) and 10(-3) A/cm(2) at 1 V reverse bias. the interface charge density was less than or equal to 10(13) cm. and flat band voltages were from -10 t o 2 V. The dielectric permittivity was between 4 and 11 for thick layers (g reater than or equal to 100 Angstrom) and decreased to values between 2 and 6 for thicknesses below 100 Angstrom. (C) 2001 Elsevier Science S.V. All r ights reserved.