P. J. Silverman

Profiling nitrogen in ultrathin silicon oxynitrides with angle-resolved x-ray photoelectron spectroscopy

Angle-resolved x-ray photoelectron spectroscopy (AR–XPS) is utilized in this work to accurately and nondestructively determine the nitrogen concentration and profile in ultrathin SiOxNy films. With furnace growth at 800–850u200a°C using nitric oxide (NO) and oxygen, 1013–1015 cm−2 of nitrogen is incorporated in the ultrathin (⩽4 nm) oxide films. Additional nitrogen can be incorporated by low energy ion (15N2) implantation. The nitrogen profile and nitrogen chemical bonding states are analyzed as a function of the depth to understand the distribution of nitrogen incorporation during the SiOxNy thermal growth process. AR–XPS is shown to yield accurate nitrogen profiles that agree well with both medium energy ion scattering and secondary ion mass spectrometry analysis. Preferential nitrogen accumulation near the SiOxNy/Si interface is observed with a NO annealing, and nitrogen is shown to bond to both silicon and oxygen in multiple distinct chemical states, whose thermal stability bears implications on the relia...

Multi-component high-K gate dielectrics for the silicon industry

Abstract The exponential growth of the silicon industry can be attributed to that fact that silicon has a native oxide that is silicon dioxide. With SiO 2 soon approaching its fundamental limit, we must find an alternate to SiO 2 or a new switch to replace MOSFETs. In this paper we focus on the leading alternate gate dielectrics. We first discuss the selection criteria for alternate gate dielectrics and why it is important to have an amorphous gate dielectric. SiO 2 and aluminum oxide remain amorphous at very high temperatures. For dielectrics with K >15 and gate power 2 , it may be necessary to stabilize the amorphous phase of metal oxides by adding Al or Si to the oxide, thus forming multi-component dielectrics such as aluminates. We then benchmark aluminates with aluminum oxide and silicon dioxide.

Gate oxide reliability projection to the sub-2 nm regime

The important components of reliability projection are investigated. Acceleration parameters are obtained for a 1.6xa0nm oxide with a soft breakdown criterion. Based on the physical percolation model, the voltage scaling factor for time to breakdown is found to increase with lower voltage, explaining the experimental observation of 6.7 ± 0.4xa0decxa0V-1 for the 1.6xa0nm oxide. The distribution of breakdown times is shown to be sensitive to thickness variation across the test wafer, and a Weibull slope of 1.38 ± 0.1 was obtained. The temperature dependence of the time to breakdown was found to be non-Arrhenius and to have a slope of 0.02xa0decxa0°C-1. Using these parameters, the 1.6xa0nm oxide was found to have a 10xa0year lifetime with a 100xa0ppm failure rate for 1.3xa0V operation at 100xa0°C. Our understanding of soft breakdown is described as well as an investigation of device operation after soft breakdown, which may further improve the reliability projection.

Understanding the limits of ultrathin SiO 2 and Si-O-N gate dielectrics for sub-50 nm CMOS

Abstract In spite of its many attributes such as nativity to silicon, low interfacial defect density, high melting point, large energy gap, high resistivity, and good dielectric strength, SiO 2 suffers from one disadvantage, low dielectric constant (K=3.9). Thus, ultrathin SiO 2 gate dielectric layers are required to generate the high capacitance and drive current required of sub-50 nm transistors. The silicon industry roadmap dictates 4 nm SiO 2 gate dielectrics for 0.25 μm technology today, and calls for 2 thickness for 0.05 μm technology in 2012. SiO 2 layers in this thickness range may suffer from boron penetration, reduced drive current, reliability degradation, and high gate leakage current. We will argue that none of these problems are limitations for thicknesses greater than about 1.3 nm. Below that thickness, the fundamental problems of high tunneling current and reduced current drive will prevent further scaling, unless alternate gate dielectrics are introduced.

Studies of electrically active defects in relaxed GeSi films using a near-field scanning optical microscope

We study the electrical activity of threading dislocation defects in relaxed GeSi films with a novel, high‐resolution optical technique. A near‐field scanning optical microscope is used to measure spatially resolved photoresponse while simultaneously imaging the surface topography. We have convincingly established that shallow topographic depressions in these films are electrically active threading dislocations. The apparent sizes of the dislocations in the photovoltage images are in agreement with estimates based on the junction geometry and the near‐field optical excitation spot size. We can clearly observe photoresponse changes at ≤100 nm lateral scale, a tenfold improvement from far‐field optical techniques. This higher resolution is due to reduction of the excitation volume and of the carrier lifetime near defects.

Ultra-thin gate oxide reliability projections

Abstract We describe the reliability projection methods currently used and show that 1.6 nm oxides are sufficiently reliable even if soft breakdown is considered the point of failure. We also explore the possibility of using oxides after soft breakdown.