J. M. Anthony

Hafnium and zirconium silicates for advanced gate dielectrics

Hafnium and zirconium silicate (HfSixOy and ZrSixOy, respectively) gate dielectric films with metal contents ranging from ∼3 to 30 at. % Hf, or 2 to 27 at. % Zr (±1 at. % for Hf and Zr, respectively, within a given film), have been investigated, and films with ∼2–8 at. % Hf or Zr exhibit excellent electrical properties and high thermal stability in direct contact with Si. Capacitance–voltage measurements show an equivalent oxide thickness tox of about 18 A (21 A) for a 50 A HfSixOy (50 A ZrSixOy) film deposited directly on a Si substrate. Current–voltage measurements show for the same films a leakage current of less than 2×10−6 A/cm2 at 1.0 V bias. Hysteresis in these films is measured to be less than 10 mV, the breakdown field is measured to be EBD∼10 MV/cm, and the midgap interface state density is estimated to be Dit∼1–5×1011 cm−2 eV−1. Au electrodes produce excellent electrical properties, while Al electrodes produce very good electrical results, but also react with the silicates, creating a lower e l...

Thin‐film interactions in Si/SiO2/W‐Ti/Al‐1% Si system

The thin‐film metal‐metal interactions in the Si/SiO2/W‐Ti/Al‐1% Si system have been studied by transmission electron microscopy, glancing angle x‐ray diffraction, Rutherford backscattering spectrometry, and secondary ion mass spectrometry techniques. The reaction is predominantly controlled by the diffusion of tungsten into the Al–1% Si layer and the sequence of the compound formation follows the prediction of the binary Al‐W phase diagram. It was shown that Al12W forms first after sintering for 30 min at 450 °C. The Al12W phase then grows from the W‐Ti/Al‐1% Si interface into the Al layer. At a temperature somewhere between 500 and 520 °C the entire Al layer is transformed to Al12W and then a more tungsten‐rich phase, Al5W, starts to form at the W/Al12W interface. As the sintering temperature is increased, the Al5W phase grows into the Al12W layer. The transformation of Al to Al12W is accompanied by a significant deterioration of the top surface quality. The internal morphology of the Al‐W phase is high...

Epitaxial and interface properties of InAs/InGaSb multilayered structures

We have used the technique of molecular beam epitaxy to grow InAs on GaSb, GaSb on InAs, and InAs/InxGa1−xSb (0≤x≤0.4) multilayered structures and have performed a detailed investigation of the layers and resultant interfaces. The structures were grown on (100) oriented GaSb or GaAs substrates. Combined reflection high energy electron diffraction, x‐ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) studies indicate that Sb is persistently present on the InAs growth surface. XPS and AES analysis of InAs/GaSb heterojunctions indicates no compound formation at either the InAs/GaSb or GaSb/InAs interface. Secondary ion mass spectroscopy (SIMS) and XPS extinction profiles reveal the presence of approximately 5–10% As in the nominally pure GaSb layers. Analysis of InAs/GaSb/GaSb (100) structures by SIMS indicates that the As is incorporated during growth. The multilayer structures have been characterized by double crystal x‐ray diffraction and the data has been modeled using kinematic ...

Investigation of molecular‐beam epitaxially grown InAs/(In,Ga)Sb strained‐layer superlattices

We report on an investigation into the molecular‐beam epitaxial growth and characterization of InAs/InxGa1−xSb (0≤x≤0.4) heterojunctions and strained‐layer superlattices (SLS) for long‐wavelength infrared detector applications. All structures have been grown on GaSb(100) substrates with period thicknesses of the SLS in the range 25–180 A. Interface properties of single heterojunction structures have been characterized by x‐ray photoelectron spectroscopy and secondary‐ion mass spectroscopy depth profiles, and structural properties of the SLS have been assessed by transmission electron microscopy and x‐ray diffraction analysis. For growth at an optimal temperature (390 °C) the SLS are of high structural quality, with no evidence of compound formation at either (GaSb/InAs, InAs/GaSb) interface, or of post‐growth interdiffusion. However, significant levels of As (7%) are found to be present in nominally grown InxGa1−xSb layers, resulting from incorporation from background. Fourier transform infrared absorptio...

Deuterium sintering of silicon-on-insulator structures: D diffusion and replacement reactions at the SiO2/Si interface

We use dynamic secondary ion mass spectrometry (SIMS) to examine the mechanism of H (D) incorporation into and retention within a buried SiO2 film at 625 °C. We find that diffusion of H2 (D2) through the Si/SiO2/Si structure at this temperature is facile and that isotopic exchange occurs at the interfaces upon subsequent forming gas anneals at 625 °C. A detailed examination of the isotopic exchange process indicates that the interfaces do not exhibit equivalent behavior. We also describe the artifacts observed in the SIMS profiles by comparing positive and negative secondary ion profiles.