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COMPARISON OF MOCVD PRECURSORS FOR Hf1-xSixO2 GATE DIELECTRIC DEPOSITION B.C. Hendrix,1 A.S. Borovik1, Z. Wang1, C. Xu1, J.F. Roeder1, T. H. Baum1, M.J. Bevan,2 M.R. Visokay2, J.J. Chambers2, A.L.P. Rotondaro2, H. Bu2, L. Colombo2 1 ATMI, 7 Commerce Drive, Danbury, CT 06810, U.S.A. 2 Texas Instruments, PO Box 650311 M/S 3737, Dallas TX 75265, U.S.A. ABSTRACT This study investigates and compares the deposition of Hf1-xSixO2 films from two suites of metalorganic CVD precursors. The first precursor suite has oxygen coordinated to the Si or Hf center and includes β-diketonate, alcoxide and acetoxy ligands. The second precursor suite has alkylamido ligands, which have nitrogen coordinated to the Hf or Si center. The process space for deposition of silicates was evaluated for controlling the composition of the silicate films while optimizing deposition rates for a manufacturable single-wafer process. The composition of the film, x, is controlled over the entire range by changing the composition of the precursor solution, Si:Si+Hf. The composition of the films, including hafnium, silicon, oxygen, carbon, and nitrogen content were measured by XPS. Both suites of precursors provide routes by which composition can be controlled in fully oxidized films with low carbon and nitrogen content. Film deposition rates are consistent with manufacturing requirements. The interfacial layers that were observed by HRTEM between the film and the substrate were thin (< 10Å) and possibly graded in composition.

INTRODUCTION Silicates of Y, La, Zr, or Hf are leading contenders for replacing silicon oxynitride as the gate dielectric material in CMOS devices. Silicates as defined herein cover the entire composition range from SiO2 to MOx and are regarded as a homogenous mixture of the binary oxides. (For a recent review, see [1].) Although binary oxides of these metals, MOx, have no thermodynamic driving force to decompose to silicides at elevated temperatures, they do tend to crystallize at lower temperatures, leaving defects such as grain boundaries in the gate dielectric. Increasing the SiO2 composition of the silicate increases the thermal stability of the amorphous structure [2]. A SiO2 content (x in Hf1-xSixO2) greater than 50% will probably be required to maintain the amorphous structure during thermal processing to 1000oC or above [3], and a SiO2 content less than 90% will be required to gain a significant increase in capacitance [4]. Silicates also have the added advantage over the binary oxides in that etching behavior that is more comparable to SiO2 [5]. Hafnium silicates have the advantage over zirconium silicates in maintaining a homogeneous, amorphous structure to higher annealing temperatures [6], and hafnium is found to have a much lower diffusivity into the Si (100) surface than zirconium [7]. Demonstrations of lanthanum and yttrium silicate MOS-caps have generally shown significant amounts of fixed charge [8], leaving hafnium silicate as the leading candidate for high κ gate dielectric material. CVD is being considered for dep