Metallorganic Chemical Vapor Deposition of Dysprosium Scandate High-k Layers Using mmp-Type Precursors

Abstract

Rare-earth scandate materials have been identified as candidates for gate dielectrics in metal oxide semiconductor transistors because of their high thermal stability against crystallization in combination with a high-dielectric constant. In this study. tris(1methoxy-2-methyl-2-propoxy)dysprosium [Dy(mmp)3] and Sc(mmp)3 are evaluated as metallorganic chemical vapor deposition precursors for deposition of DyxSc yOz on silicon at moderate temperatures (450-600°C). These temperatures allow easy integration into a standard transistor flow. The layers are uniform with a close to bulk density and smooth top surface. Electrical characterization measurements shows a gate leakage current of 1.8 × 10-5 A/cm2 at 4.5 V for an equivalent oxide thickness of 2.0 nm. Limited hysteresis (9 mV) and .frecmencv dispersion (3% difference in accumulation capacitance between 10 and 1250 kHz) was observed. © 2006 The Electrochemical Society. All rights reserved.