摘要:

Recent advances in the technology and understanding of ohmic contacts for a variety of III–V compound semiconductor material systems are reviewed. Special attention is focused on factors and critical issues involved in making low resistance and reliable ohmic contacts. The solid‐phase regrowth mechanisms of key metallization systems are described. In addition, special techniques to improve the ohmic contacts are discussed. Finally, the reliability issues of ohmic contacts are addressed.

ISSN:1071-1023    

DOI:10.1116/1.586179

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

As we enter the era of ultra‐large‐scale integrated circuit manufacture, plasma etching grows more important for fabricating structures with unprecedented dimensions. For feature sizes below 1 μm and aspect ratios (depth/width) much larger than one, etching rates have been observed to depend on aspect ratio and pattern density. Such dependencies tend to increase the cost of manufacturing because even small changes in device design rules, cell design, or wafer layout can result in time‐consuming, new plasma process development. In addition, microscopically nonuniform etching affects the trade‐off between chips lost from failure to clear and chips lost by damage from overetching. Although aspect ratio and pattern dependent etching have been observed for a large variety of material systems and processing conditions, the fundamental causes underlying these effects are poorly understood. Partly, this results from use of confusing and conflicting nomenclature and a lack of careful, quantitative comparisons between experiment and theory. In this article we review recent literature on microscopic uniformity in plasma etching and carefully define terminology to distinguish between aspect ratio dependent etching (ARDE) and the pattern dependent effect known as microloading. For ARDE, we use dimensional analysis to narrow the range of proposed mechanisms to four which involve ion transport, neutral transport, and surface charging. For microloading, we show that it is formally equivalent to the usual loading effect, where the reactant concentration is depeleted as a result of an excessive substrate load.

ISSN:1071-1023    

DOI:10.1116/1.586180

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The influence of molecular‐beam epitaxy growth conditions, especially oxide desorption and growth temperature, on the final quality of InAlAs layers grown on (100) InP substrates, has been analyzed by conventional and high‐resolution transmission electron microscopy observations. InP thermal cleaning prior growth at 500 °C has been found to produce rough interfaces and extended defects which propagate up to the surface, while thermal cleaning at 530 °C results in abrupt interfaces and improved epilayer structure. The increase of growth temperature up to 530 °C, also improves the crystalline quality of InAlAs.

ISSN:1071-1023    

DOI:10.1116/1.586181

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The authors have investigated the effect ofinsituhydrogen plasmas generated by electron cyclotron resonance on growth rate and carbon incorporation in GaAs and AlGaAs grown by metalorganic molecular‐beam epitaxy using triethylgallium and trimethylamine alane. Carbon backgrounds in GaAs grown at 500 °C were found to increase with increasing microwave power over the range 100–200 W and also with increasing H2flow at 175 W. Hydrogen plasmas did not significantly increase the growth rate for either GaAs or AlGaAs even at growth temperatures as low as 375 °C. As at higher temperatures, carbon levels were not reduced in GaAs grown at low temperatures though some improvement was observed for AlGaAs grown at 375 °C. Plasmas were found to be much more effective for cleaning substrates prior to growth. At 500 °C, low microwave powers and moderate exposure times were found to produce the lowest levels of interfacial C, O, and Si contamination.

ISSN:1071-1023    

DOI:10.1116/1.586182

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

GaAs layers were grown by molecular‐beam epitaxy and by migration‐enhanced epitaxy (MEE) on pseudomorphic Si films grown on GaAs(100) substrates. The Si interlayer thickness (tSi) was varied from 0 to 3 monolayers (ML), and the effect on the GaAs growth mode was investigated by observing the behavior of the intensity of the specular spot of reflection high‐energy electron diffraction patterns. From these measurements it was concluded that the surface migration of Ga atoms is disturbed by the Si atoms on the growing surface. The disturbance increased, at the growth temperature of 520 °C, with increasing the Si interlayer thickness to the point that fortSi≥0.4 ML, the two‐dimensional (2D) growth changed to a three‐dimensional one. By increasing the growth temperature, the growth mode improved but the Si surface segregation increased, as detected by secondary ion mass spectrometry. The effect of the thermally activated Si segregation process on the GaAs growth mode is discussed. Using MEE at a growth temperature of 480 °C, the Si segregation was eliminated and a 2D growth mode was obtained.

ISSN:1071-1023    

DOI:10.1116/1.586183

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The reactions of diethylzinc (DEZ) on the GaAs(100) surface have been studied using temperature programmed desorption, x‐ray photoelectron spectroscopy (XPS), and high‐resolution electron energy‐loss spectroscopy. DEZ dissociated on the GaAs(100) surface below room temperature forming adsorbed zinc atoms and ethyl groups. The adsorbed zinc metal interacted weakly with the GaAs(100) surface and desorbed near 530 K. The ethyl species formed via DEZ dissociation bond to surface Ga atoms. The resulting surface ethyl‐Ga complexes were stable to approximately 500 K at which point they reacted to form ethylene, hydrogen, and smaller amounts of ethyl radicals and ethane. At high surface ethyl coverages a fraction of the ethyl‐Ga species reacted between 300 and 500 K to form gaseous galliumalkyls. XPS results demonstrate that the decomposition of the adsorbed ethyl groups did not result in carbon deposition onto the surface.

ISSN:1071-1023    

DOI:10.1116/1.586184

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

An electron cyclotron resonance microwave plasma processing system consisting of a plasma chamber and a processing chamber as well as a new apparatus called the ‘‘species selector and energy controller (SSEC)’’ are described in detail. Silicon dioxide (SiO2) films fabricated using this system without and with the SSEC are used for various experiments to demonstrate that the SSEC can effectively suppress the damaging effects resulting from the bombardment on the substrates and the on‐growing films by energetic particles and photons produced in the plasma during film deposition, as well as effectively reduce the upstream diffusion of the reactant gas from the processing chamber to the plasma chamber, thus suppressing the formation of microdust particles due to the heterogeneous gas phase reaction. The film growth for the films fabricated without the SSEC is due mainly to mass‐limited reaction and that with the SSEC is due to surface rate‐limited reaction. The electronic properties of the SiO2films fabricated with the SSEC at temperatures higher than 250 °C approach those of high‐quality thermally grown silicon oxides. The effects of the SSEC on the film properties and the film growth mechanism are also discussed.    

ISSN:1071-1023    

DOI:10.1116/1.586185

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Chlorine chemistries are often used for the radio‐frequency (rf) discharge plasma etching of compound semiconductors, metals, and silicon. A variety of gas mixtures are used as Cl atom donors, many of which have different electron transport coefficients. In this article we computationally investigate 13.56 MHz rf discharges sustained in He/Cl2, He/HCl, and He/CCl4gas mixtures in the context of plasma etching. The study is performed using a Monte Carlo‐fluid hybrid model of rf discharges. We find that the Cl atom production efficiency is surprisingly similar in these mixtures, while the details of the electron transport (sources of ionization, locations of attachment, electronegativity) dramatically differ. We also find that even at the low pressures of interest (0.25–1 Torr) attachment in He/HCl mixtures is dominated by vibrationally excited HCl, in analogy to high‐pressure discharge devices.

ISSN:1071-1023    

DOI:10.1116/1.586186

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The cause of anisotropic etching of a reactive ion etching (RIE) process for InP/InGaAsP involving a mixture of Cl2, Ar, CH4, and H2is investigated, applying Auger photoelectron spectroscopy and transmission electron spectroscopy. The extend of sidewall damage is given. An InP/InGaAsP heterostructure quantum wirelike structure is fabricated and the effect on the photoluminescence intensity and wavelength is reported. Successful device fabrication using RIE is demonstrated.

ISSN:1071-1023    

DOI:10.1116/1.586187

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The effect of adding SF6or C2H6to Cl2plasma to control the pattern profile in poly‐Si etching has been studied using a magnetron reactive ion etching system. It is found that the sidewalls of patterns etched with pure Cl2plasma are either sloped or vertical depending on whether a radio‐frequency (rf) power of 700 W (0.9 W/cm2) or 600 W(0.77 W/cm2) is applied. By increasing the content of SF6the angle of the sidewall taper of the pattern etched at 700 W rf power reaches 90°. Adding C2H6makes it possible to adjust the slope of the sidewall over a range from 77° to 90° at a rf power of 600 W. These observed results are attributed to plasma polymerization.

ISSN:1071-1023    

DOI:10.1116/1.586188

出版商:American Vacuum Society    

年代:1992

数据来源: AIP