H. Barry Harrison

INTERFACIAL CHARACTERISTICS OF N2O AND NO NITRIDED SIO2 GROWN ON SIC BY RAPID THERMAL PROCESSING

Interfacial characteristics of Al/SiO2/n-type 6H–SiC metal–oxide–semiconductor capacitors fabricated by rapid thermal processing (RTP) with N2O and NO annealing are investigated. Interface state density was measured by a conductance technique at room temperature. RTP oxidation in pure O2 leads to an excellent SiO2/n-type 6H–SiC interface with interface state density in the order of 1010–1011 eV−1 cm−2. NO annealing improves the SiO2/n-type 6H–SiC interface, while N2O annealing increases the interface state density.

Electrical and physical characterization of gate oxides on 4H-SiC grown in diluted N2O

A systematic electrical and physical characterization of gate oxides on 4H-SiC, grown in diluted N2O at 1300 °C, has been performed. Electrical characterization by the high-frequency C-V technique, conductance technique, and slow trap profiling method reveals that the densities of interface and near-interface traps, and the effective oxide charge for gate oxides grown in 10% N2O are the lowest, compared to gate oxides grown in 100% and 0.5% N2O. These results are supported by physical characterizations using x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and atomic force microscopy. It has been shown that carbon clusters, accumulated at the SiC-SiO2 interface, directly influence the roughness of the interface and the densities of the interface and near-interface traps.

Investigation of nitric oxide and Ar annealed SiO2/SiC interfaces by x-ray photoelectron spectroscopy

Silicon dioxide (SiO2)/silicon carbide (SiC) structures annealed in nitric oxide (NO) and argon gas ambiences were investigated using x-ray photoelectron spectroscopy (XPS). The XPS depth profile analysis shows a nitrogen pileup of 1.6 at. % close to the NO annealed SiO2/SiC interface. The results of Si 2p, C 1s, O 1s, and N 1s core-level spectra are presented in detail to demonstrate significant differences between NO and Ar annealed samples. A SiO2/SiC interface with complex intermediate oxide/carbon states is found in the case of the Ar annealed sample, while the NO annealed SiO2/SiC interface is free of these compounds. The Si 2p spectrum of the Ar annealed sample is much broader than that of the NO annealed sample and can be fitted with three peaks compared with the two peaks in the NO annealed sample, indicating a more complex interface in the Ar annealed sample. Also the O 1s spectrum of the NO annealed samples is narrow and symmetrical and can be fitted with only one peak whereas that of the Ar an...

Anisotropic etching of {100} and {110} planes in (100) silicon

Anisotropic etching of (100) silicon using KOH with 45° alignment to the primary 110 wafer flat was investigated. It was shown that in KOH solution with isopropyl alcohol added, high KOH concentration and temperature caused the selection of {100} instead of {110} walls, allowing reliable fabrication of {100} walls with improved surface smoothness due to the isopropyl alcohol. TMAOH solutions with methanol and isopropyl alcohol were also found to produce both types of wall, with excellent surface smoothness for the {110} walls. A new maskless etching technique was developed for corner compensation of structures bounded by {110} walls.

Slow-trap profiling of NO and N2O nitrided oxides grown on Si and SiC substrates

In this paper, we demonstrate the unique ability of a newly developed slow-trap profiling technique to characterise silicon-based MOS capacitors in strong inversion. We also demonstrate the applicability of the slow-trap profiling technique for the characterisation of oxides grown on SiC. The obtained slow-trap profiles show that NO nitridation eliminates while N2O creates defects acting as slow traps in the case of both Si and SiC substrates. The corresponding effects of nitridation on interface traps and fixed oxide charge are also discussed.

Model for dielectric growth on silicon in a nitrous oxide environment

In this letter, a model for growth kinetics of ultrathin dielectrics obtained by oxidation of silicon in a nitrous oxide environment is proposed. The model assumes that the oxide growth is limited by time‐dependent interface reaction, which is slowed down and eventually completely blocked as oxide growth sites are neutralized by nitrogen atoms. The model fits experimental data extremely well, both with time and temperature.

Modeling the growth of thin silicon oxide films on silicon

This article analyses the validity of the widely used semi‐empirical oxidation models based on the Deal‐Grove formulation in the light of recent advances in the understanding of the oxidation process. An extension of the Deal‐Grove formulation is suggested to account for the newest experimental results. The introduced extension incorporates the effect of accelerated initial growth into the theoretical oxidation growth model. There is a direct relationship between the newly‐derived theoretical term for the initial growth rate and its widely‐used empirical counterpart.

Analysis of Fowler–Nordheim injection in NO nitrided gate oxide grown on n-type 4H–SiC

Abstract Fowler–Nordheim injection in NO nitrided gate oxides, grown on n-type 4H–SiC, has been investigated at room temperature and 300°C. The results show that NO increases the electron injection barrier height to a value which is very close to the theoretical value at room temperature. Excessive temperature dependence of the electron injection barrier height is also significantly reduced by the nitridation.

Charge retention in metal–oxide–semiconductor capacitors on SiC used as nonvolatile-memory elements

In this letter, the possibility of using metal–oxide–semiconductor capacitors on SiC as nonvolatile random-access memory elements has been experimentally investigated. Because of the wide energy gap and the very low minority-carrier generation rate in SiC, it should be possible to achieve very long retention times. The investigations show that charge leakage through the gate oxide may prevent the use of SiC metal–oxide–semiconductor (MOS) capacitors as memory elements. Importantly, the experiments demonstrate that both the charge leakage and carrier-generation rate are low in the case of nitrided SiO2–SiC interfaces. The retention time extrapolated to room temperature is in the order of 109 years for the case of MOS capacitors on 4H–SiC, which is approximately equal to the theoretical limit.

Improved Operation of Micromechanical Comb-Drive Actuators through the Use of a New Angled Comb Finger Design:

An original design for a new comb finger structure to be used in electrostatically driven actuator devices is presented and experimentally demonstrated. The new design is seen as one viable alternative to the already prevalent rectangular comb finger design and can be considered as a crossbreed between a conventional comb finger design (0 = 0 a parallel-plate design (0 = 900). The design topology is verified both analytically, to show the validity of fundamental effects, and experimentally. Experimental results show the fabricated device based on the new comb finger design achieves twice the displacement of a standard rectangular comb finger based device under equal operating conditions, hence demonstrating twice the force generation capability, while at the same time maintaining overall device stability.