Physical and electrical properties of noncrystalline Al2O3 prepared by remote plasma enhanced chemical vapor deposition

Noncrystalline Al2O3 dielectric films have been synthesized by remote plasm a enhanced chemical vapor deposition (RPECVD) and deposited on (i) H-termin ated Si(100) and (ii) on SiO2 prepared by remote plasma assisted oxidation and RPECVD on Si(100) substrates using organometallic source gases injected downstream from a He/O-2 plasma. Chemical composition and morphology of th e Al2O3 films and their interfaces have been studied by Auger electron spec troscopy (AES), Fourier transform infrared spectroscopy, nuclear resonance profiling (NRP), and x-ray diffraction (XRD). Previous studies in which Al2 O3 was deposited by thermal CVD, rapid thermal CVD. (RTCVD), direct PECVD, and physical vapor deposition generally resulted in relatively thick SiO2 o r Al-silicate interfacial layers which impact adversely on the highest atta inable capacitance, In line AES and NRP indicate the as-deposited RPECVD fi lms are fully oxidized on deposition, and their interfaces can be chemicall y abrupt with Si oxide or Al silicate interfacial layers that are no more t han 0.6 to 0.8 nm thick. However, these relatively abrupt interfaces do not ensure good device performance. Electrical measurements indicate negative fixed charge on the order of 10(12) charges/cm(2). The fixed charge resides at the Al2O3 interface, and can be moved away from the silicon substrate b y deposition of a thin, similar to1-2 nm, intermediate layer of RPECVD SiO2 . (C) 2001 American Vacuum Society.