Zirconium silicate films obtained from novel MOCVD precursors

Abstract

The potential of zirconium silicate films as an alternative gate dielectric to silicon oxide in future technology generations is demonstrated. Novel single-source precursors for metal organic chemical vapor deposition (MOCVD) of zirconium silicate films are presented. These precursors meet the demands for implementation in a MOCVD process in respect to purity, volatility, and deposition temperature. Zirconium silicate layers were deposited and metal insulator semiconductor capacitors were manufactured. Structural characterization of the films was performed by means of X-ray photoelectron spectroscopy, secondary neutral mass spectroscopy, transmission electron microscopy, and ellipsometry. It was found that the silicon content in the zirconium silicate films is less than stoichiometric and carbon free films can only be obtained at deposition temperatures above 550 °C. The permittivity of the films is about 10.5–15. Electrical characterization by capacitance as a functions of voltage and current as a function of voltage measurement techniques show very promising results: low leakage current (5 × 10 −9 A/cm 2 at −3 V), low level of bulk charge (5 to 6 × 10 11 cm −2), and small hysteresis (about 50 mV) were obtained. However, some instabilities, i.e negative charge trapping (up to 2 × 10 12 cm −2) during electrical stress, have also been encountered and further investigations should aim at reducing this charge trapping.