Search

© 2003 American Institute of Physics. The authors acknowledge C.A.I. de Implantación Iónica (U.C.M.) for technical support, and especially to Rosa Cimas Cuevas for aid in sample processing, and C.A.I. de Espectroscopia (U.C.M.) for providing access to the FTIR spectrometer. This work was partially supported by the Spanish CICYT, under Contract No. TIC 01-1253., The composition, bonding configuration, hydrogen content, and paramagnetic defects of SiOxHy thin films were studied. Films were deposited by the electron cyclotron resonance plasma method at room temperature using SiH4 and O-2 as precursor gases. The film composition was measured by heavy ion elastic recoil detection analysis and energy dispersive x-ray spectroscopy. Suboxide films with compositions ranging from SiO2 to SiH0.38 were obtained. Infrared spectroscopy showed the presence of different Si-O and Si-H vibration modes. The usual estimation of the oxygen to silicon ratio by the wave number of the Si-O-Si stretching band was not accurate for films far from stoichiometry. These off-stoichiometric films also showed a broader Si-O-Si stretching peak than the stoichiometric ones, indicating a higher bonding disorder. The position of the Si-O-Si bending and rocking modes did not depend on the film composition. On the other hand, the peak position of the Si-H modes were found strongly dependent on the Si environment. By single-wavelength ellipsometry at lambda=632.8 nm the refractive index n was found to range between 1.45 (SiO2) and 2.04 (SiO0.06H0.36). Electron spin resonance measurements showed that stoichiometric films presented the well known E' center (.Siequivalent toO(3)) with concentrations in the 10(16)-10(17) cm(-3) range, while for Si-rich films (x<1) the Si dangling bond center (Si-DB, .Siequivalent toSi(3)) was the only detectable defect, with concentrations in the 10(18)-10(19) cm(-3) range. In near-stoichiometric films both E-' and Si-DB centers were found., Spanish CICYT, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2001 IOP Publishing Ltd. We wish to thank the financial support of the Spanish National Office for Science and Technology under grant no TIC98-0740 and the technical assistance of the ion implantation center ‘CAI-Implantación Iónica’ of the University of Madrid., A comparative investigation of the characteristics of the SiNx:H/Si interface has been undertaken by capacitance-voltage measurements and surface photovoltage spectroscopy. By each of these techniques, we have determined the distribution of the interface trap density within the silicon bandgap. The samples were grown by the electron-cyclotron resonance plasma method starting from SiH4 and N-2 as precursor gases whose flow ratio was varied to produce films of three different compositions: silicon rich, near stoichiometric and nitrogen rich. Post-deposition rapid thermal annealing treatments were applied to observe the evolution of interface properties with the annealing temperature in the range from 300 to 1050 degreesC. For thin dielectrics, the interface state density has a U-shaped distribution dominated by hand-tail states. The minimum of this distribution decreases significantly and shifts to midgap for moderate annealing temperatures. For higher annealing temperatures, the trend is reversed. In the silicon-rich films, the percolation of rigidity caused by the chains of Si-Si bonds impedes the initial decrease of the defect density. For thicker films, the strain of the: SiNx:H film produces a higher density of defects that results in increased levels of leakage currents and poorer electrical characteristics., Spanish National Office for Science and Technology, Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub

© 2003 American Vacuum Society., We present a comparative study of the electrical and structural characteristics of metal-insulator-semiconductor (MIS) devices using SiN1.55:H or SiN1.55:H/SiOx stacks as gate dielectrics, with the aim of improving the thermal stability of the SiN1.55:H/Si interface. The dielectrics were grown on Si by the electron cyclotron resonance plasma method. The stacks were produced by plasma oxidation of the Si surface, resulting in a thin layer of SiOx (PO-SiOx), followed by deposition of the SiN1.55:H layer. Afterwards, the samples were rapid thermally annealed (RTA) at temperatures ranging from 300 to 1000degreesC. Some representative samples were studied by Fourier transform infrared spectroscopy to characterize the bonding structure of the SiN1.55:H/PO-SiOx stack and its evolution with the annealing temperature. The results were in good agreement with the well known model for suboxide evolution with the temperature: the formation of highly defective nanocrystalline Si clusters inside a high quality SiO2 matrix. This process takes place for RTA temperatures higher than 700degreesC. This model also explains the results derived from C-V measurements, which show improvement of the PO-SiOx/Si interface as a result of the formation of the high quality SiO2 matrix. Additionally, the thermal stability improved with respect to the SiN1.55:H/Si interface, which suffers significant degradation when annealed above 600degreesC, while devices made with the stacks are able to hold annealing temperatures up to 900degreesC. On the other hand, the formation of nc-Si results in degradation of the reliability of the MIS devices., Depto. de Estructura de la Materia, Física Térmica y Electrónica, Fac. de Ciencias Físicas, TRUE, pub