dielectric films have been synthesized by remote plasma enhanced chemical vapor deposition ͑RPECVD͒ and deposited on ͑i͒ H-terminated Si͑100͒ and ͑ii͒ on SiO 2 prepared by remote plasma assisted oxidation and RPECVD on Si͑100͒ substrates using organometallic source gases injected downstream from a He/O 2 plasma. Chemical composition and morphology of the Al 2 O 3 films and their interfaces have been studied by Auger electron spectroscopy ͑AES͒, Fourier transform infrared spectroscopy, nuclear resonance profiling ͑NRP͒, and x-ray diffraction ͑XRD͒. Previous studies in which Al 2 O 3 was deposited by thermal CVD, rapid thermal CVD, ͑RTCVD͒, direct PECVD, and physical vapor deposition generally resulted in relatively thick SiO 2 or Al-silicate interfacial layers which impact adversely on the highest attainable capacitance. In line AES and NRP indicate the as-deposited RPECVD films are fully oxidized on deposition, and their interfaces can be chemically abrupt with Si oxide or Al silicate interfacial layers that are no more than 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 Al 2 O 3 interface, and can be moved away from the silicon substrate by deposition of a thin, ϳ1-2 nm, intermediate layer of RPECVD SiO 2 .

A localized molecular orbital description ͑LMO͒ for the electronic states of transition metal ͑TM͒ noncrystalline silicate and aluminate alloys establishes that the lowest conduction band states are derived from d states of TM atoms. The relative energies of these states are in agreement with the LMO approach, and have been measured by x-ray absorption spectroscopy for ZrO 2-SiO 2 alloys, and deduced from an interpretation of capacitance-voltage and current-voltage data for capacitors with Al 2 O 3-Ta 2 O 5 alloy dielectrics. The LMO model yields a scaling relationship for band offset energies providing a guideline for selection of gate dielectrics for advanced Si devices.

Articles you may be interested inEffects of denuded zone of Si ( 111 ) surface on current conduction and charge trapping of HfO x N y gate dielectric in metal-oxide-semiconductor devices Appl. Phys. Lett. 85, 4723 (2004); 10.1063/1.1819994Effects of plasma nitridation of Al 2 O 3 interlayer on thermal stability, fixed charge density, and interfacial trap states of HfO 2 gate dielectric films grown by atomic layer deposition

We present experimental results on single-event-induced breakdown in sub-5-nm plasma-enhanced SiO 2 , nitrided SiO 2 , Al 2 O 3 , HfO 2 , and Zr 0 4 Si 1 6 O 4 dielectrics typical of current and future-generation commercial gate oxides. These advanced oxides are found to be quite resistant to ion-induced breakdown. Radiation-induced soft breakdown was observed in some films with 342 MeV Au (LET = 80 MeV/mg/cm 2) but not 340 MeV I (LET = 60 MeV/mg/cm 2). The critical voltage to hard breakdown was found to scale with the square root of the physical oxide thickness, not with the energy stored on the gate capacitance. Alternative dielectrics with equivalent oxide thickness substantially below their physical thickness were found to exhibit significantly higher voltage to hard breakdown than SiO 2 counterparts. All of the samples reached ion-induced hard breakdown at applied voltages well above typical operating power-supply voltages; these findings bode well for the use of advanced commercial integrated circuits in space systems.

Application of the simplified bond-hyperpolarizability model to fourth-harmonic generation