Silicon Carbide Technology Research Articles

Similarities and differences in sublimation growth of SiC and AlN

The similarities and differences in development of crystal growth of bulk silicon carbide (SiC) and aluminum nitride (AlN) are discussed. It is concluded that AlN is going to become the second crystal grown in production scale using PVT technique. The growth technology of AlN may take advantage of learning from SiC technology as the latter is based on significant advances achieved in the course of last 20 years. The main differences between two materials are in incongruent evaporation of SiC and in poor compatibility of AlN with regular high-temperature crucible materials.

Growth of Crystalline Silicon Carbide by CVD Using Chlorosilane Gases

AbstractThe forefront of semiconductor silicon carbide technology now approaches commercialization for both materials and device technology. The commercialization of SiC epitaxy processes requires improvement in defect density, uniformity and repeatability. Especially problematic are graphite particles, gas phase nucleation of particles and the limitations placed on achieving growth rates that can positively impact process costs. When it approached the same historical point of development, silicon epitaxy technology shifted to the use of chlorosilane precursor gases to suppress gas phase nucleation and achieve targeted growth rates. Recent work on SiC epitaxy chemistry now investigates the use of HCl, halocarbons and most recently chlorosilane precursors. This paper will review the original work on gas phase nucleation and its control in silicon epitaxy processes using HCl additives and chlorosilanes. Using established dissociation pathways for chlorosilanes, equilibrium chemical reaction models are used to assess the impact of HCl, halocarbons and chlorosilane precursors on growth rates and particle formation SiC epitaxy. Experimental data is presented on the comparative performance of HCl additive and chlorosilane precursors in SiC epitaxy and film properties.

State-of-the-Art, Single-Phase, Active Power-Factor-Correction Techniques for High-Power Applications—An Overview

A review of high-performance, state-of-the-art, active power-factor-correction (PFC) techniques for high-power, single-phase applications is presented. The merits and limitations of several PFC techniques that are used in today's network-server and telecom power supplies to maximize their conversion efficiencies are discussed. These techniques include various zero-voltage-switching and zero-current-switching, active-snubber approaches employed to reduce reverse-recovery-related switching losses, as well as techniques for the minimization of the conduction losses. Finally, the effect of recent advancements in semiconductor technology, primarily silicon-carbide technology, on the performance and design considerations of PFC converters is discussed.

Silicon carbide for high resolution X-ray detectors operating up to 100°C

This work presents experimental results on the possibility of high resolution X-ray spectroscopy in a wide temperature range, from room temperature up to 100°C without any cooling system, using Silicon Carbide (SiC) detectors. This capability arises from the very low noise of SiC detectors at high temperature because of their extremely low-leakage current density ( 20 pA/cm 2 at 24°C and 1 nA/cm 2 at 107°C with mean electric fields of 120 kV/cm ). Spectra of 241 Am acquired by a pixel SiC detector are reported with equivalent noise energies of 315 eV FWHM at 27°C and 797 eV FWHM at 100°C. The contributions of the different noise sources of the detector and of the front-end electronics are determined and analyzed. The potential for SiC X-ray detectors and open issues in SiC technology are highlighted.

Vishay signs SiC technology tranfer with DaimlerChrysler

DaimlerChrysler and Vishay Intertechnology Inc have signed an agreement to enable Vishay to undertake volume manufacture of semiconductor products using Daimler Chrysler’s silicon carbide technology. Developed at Daimler Chrysler AG since 1993, SiC enables the creation of semiconductor devices for compact power conversion systems in electric cars, railway systems, and other mobile applications. SiC devices allow smaller and lighter converter module designs which can operate at the high temperatures of these systems. This is a short news story only. Visit www.three-fives.com for the latest advanced semiconductor industry news.

Study of silicon carbide for X-ray detection and spectroscopy

This work presents an analysis of silicon carbide (SiC) as semiconductor for the realization of detectors for soft X-rays (<20 keV). On the basis of experimental data on prototype SiC junctions, the performance in X-ray spectroscopy using planar diode and drift detectors in SiC have been estimated in a wide range of operating temperature (up to 150°C). It has been derived that, due to their extremely low reverse current density (4.7 pA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 300 K and 17 pA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 340 K and at electric field of 100 kV/cm), SiC detectors can potentially reach superior performance with respect to all the other semiconductors presently employed at or above room temperature. In particular, a comparative theoretical analysis, based on experimental data on state-of-the-art silicon and SiC junctions, shows that SiC detectors with areas larger than 1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> have the potentiality to offer higher energy resolution when operating at temperature above 25°C. An energy resolution of about 700 and 1300 eV FWHM have been estimated for 1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> SiC pad detectors operating at 100°C with a silicon front-end FET. The contribution of a standard silicon front-end electronics on the system performance has been analyzed. The open issues in SiC technology for X-ray detector development are highlighted.

Nuclear Reactor Power Monitoring Using Silicon Carbide Semiconductor Radiation Detectors

Silicon carbide semiconductor neutron detectors are being developed for use as ex-vessel power monitors for pressurized water reactors. Key features such as neutron response, radiation resistance, and high-temperature operation have been explored for silicon carbide detectors, and the results are consistent with their use in the ex-vessel environment. Prototype silicon carbide ex-core neutron detectors have been assembled and tested under research reactor conditions simulating ex-core neutron monitoring requirements. Linear, pulse-mode operation without the need for gamma compensation has been demonstrated with these prototype detectors. The silicon carbide detectors are compared to presently deployed gas-filled ex-vessel detectors, and several advantages of the silicon carbide technology can be seen. It is anticipated that a wide-range silicon carbide neutron detector can be designed to replace the combined functions of the multiple power range detectors in use. Furthermore, the need for gamma-ray compensation will be eliminated, and more efficient reactor operation and simplified reactor operating procedures will result.

Silicon Carbide Technology in New Era

Silicon Carbide Technology in New Era

An IR-reflectivity and X-ray diffraction study of high energy He-ion implantation-induced damage in 4H–SiC

Due to recent progress in silicon carbide (SiC) technology, understanding the behaviour of defects in SiC is a crucial challenge for the industrial development of SiC-based devices. High energy helium ion implantation at high fluence in SiC creates a few microns deep damaged layers with nanocavities which are expected to play an important role in gettering of unwanted impurities. Post-implantation evolution of the ion implantation-induced damage is then controlled by thermal annealing. Results of an infrared reflectivity (IRR) and X-ray diffraction (XRD) study of ion implantation-induced damage in crystalline (0 0 0 1) n-type 4H–SiC implanted at room temperature with 1.6 MeV He + ions at the fluence of 10 17 cm −2 show the formation of two layers above the unperturbed crystal: a 3.4 μm deep defective strained surface layer on a 0.4 μm thick strongly perturbed interface layer. Thermal annealing at 1500 °C for 30 min under high vacuum was shown to induce structural recovery of the surface layer.

Progress in SiC: from material growth to commercial device development

Silicon carbide technology has made tremendous strides in the last several years, with a variety of encouraging device and circuit demonstrations in addition to volume production of nitride-based blue LEDs being fabricated on SiC substrates. The commercial availability of relatively large, high quality wafers of the 6H and 4H polytypes of SiC for device development has facilitated these exciting breakthroughs in laboratories throughout the world. These have occurred in numerous application areas, including high power devices, short wavelength optoelectronic devices, and high power/high frequency devices. This paper will describe progress made in increasing the quality and size of SiC wafers, advances in SiC epitaxy and some of the resulting device demonstrations and commercialization by Cree Research.

A Review of SiC Reactive Ion Etching in Fluorinated Plasmas

Research and development in semiconducting silicon carbide (SiC) technology has produced significant progress in the past five years in many areas: material (bulk and thin film) growth, device fabrication, and applications. A major factor in this rapid growth has been the development of SiC bulk crystals and the availability of crystalline substrates. Current leading applications for SiC devices include high power and high temperature devices and light emitting diodes. Due to the strong bonding between Si and C (Si–C = 1.34×Si–Si), wet chemical etching can only be performed at high temperature. Therefore, plasma-based (“dry”) etching plays the crucial role of patterning SiC for the fabrication of various electronic devices. In the past several years, reactive ion etching (RIE) of SiC polytypes (3C and 6H) has been investigated in fluorinated gases (primarily CHF3, CBrF3, CF4, SF6, and NF3), usually mixed with oxygen and occasionally with other additives or in a mixture of fluorinated gases. In this paper, a review of SiC RIE is presented. The primary emphasis is on etching of the 3C and 6H polytypes, but some results on RIE of the 4H polytype are included. The paper covers the basic etching mechanisms, provides typical etching properties in selected plasma conditions, discusses the effects of changes in various etching parameters, such as plasma pressure, density and power, etching time, etc. The etching of features of sizes varying from sub-μm to tens of μm's is addressed. Finally, optimum etching conditions and trade-offs are considered for various device configurations.

Realization of silicon carbide sensors for measurements on gaseous working fluids

A series of temperature, pressure, as well as gas or liquid flow sensors, working under extreme service conditions like high temperature, hostile environments, radiation has been carried out on the basis of a unified silicon carbide (SiC) technology. The different step include performing a low-temperature SiC epitaxy on an insulating substrate, performing a precise local dry etching using standard photoresist masks and achieving high-temperature contact fabrication. Details of these steps and corresponding applications are reviewed.

Positive temperature coefficient of breakdown voltage in 4H-SiC pn junction rectifiers

It has been suggested that once silicon carbide (SiC) technology overcomes some crystal growth obstacles, superior SiC semiconductor devices would supplant silicon in many high-power applications. However, the property of positive temperature coefficient of breakdown voltage, a behavior crucial to realizing excellent power device reliability, has not been observed in 4H-SiC, which is presently the best-suited SiC polytype for power device implementation. This paper reports the first experimental measurements of stable positive temperature coefficient behavior observed in 4H-SiC pn junction rectifiers. This research indicates that robust 4H-SiC power devices with high breakdown reliability should be achievable after SiC foundries reduce material defects such as micropipes, dislocations, and deep level impurities.

SiC Semiconductor Applications - An Air Force Perspective

AbstractThe Department of Defense (DoD) is investing in the development of Silicon Carbide (SiC) for a wide range of applications. Over the past year, SiC technology has demonstrated excellent device performance results for power devices, high temperature electronic devices and microwave devices. The materials growth and processing technology for SiC is now at a level of sufficient maturity to support substantial device development efforts. While there is still considerable materials and device research required for SiC to achieve it's full potential, the fundamental technology has been proven for several critical applications. A perspective on some Air Force device performance requirements will be presented. The status of SiC materials development, material limits to advances in device performance and issues relating to supporting technology will also be discussed.

Silicon carbide against silicon: a comparison in terms of physical properties, technology and electrical performance of power devices

The aim of the present paper is to give the state of the art of the silicon carbide technology by photographing it beside the unique technology used for power electronics that is the silicon one. The theoretical superiority of SiC physical properties on those of Si, together with the important technological advancements realized during the last decade, are the main reasons of the interest given to SiC nowadays. Concerning electrical performance, the voltage and power handling capabilities do not reach today the high expected values, and remain lower than those provided by Si. On the other hand, SiC components confirm the aptitude of this material for high temperature and high frequency applications

Silicon carbide technology for blue-emitting diodes

Silicon carbide light-emitting diodes with emission in the blue range of the spectrum have been produced by vapor growth and liquid-phase epitaxy. The technology of devices with a p-type (Al-doped) luminescent layer is described. Emission spectra and efficiency data are presented for two types of diodes.