GaAs IC Technology Research Articles

Ion implantation in gallium arsenide MESFET technology

The authors emphasize controlled shallow doping of GaAs by ion implantation and its limitations to state-of-the-art GaAs IC technology. The authors discuss the electrical activation behavior of implanted silicon in GaAs upon subsequent capless or silicon nitride capped rapid thermal annealing (RTA). It is demonstrated that atomic H diffuses into the implanted region of GaAs from a plasma-enhanced chemical vapor deposition Si/sub 3/N/sub 4/ cap during the deposition as well as during subsequent annealing, and the H retards the electrical activation kinetics of the implanted Si. Thru-Si cap dopant implants into GaAs have been studied to enhance dopant concentration in the surface region of the GaAs by recoil-implanted Si from the cap. Application of ion implantation to achieve buried-p layers in GaAs is also briefly discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Shallow Ion Implantation in Gallium Arsenide Mesfet Technology

ABSTRACTThis review emphasizes controlled shallow doping of GaAs by ion implantation for state-of-art GaAs IC technology. Electrical activation behavior of Si+ and SiF+ implanted GaAs after RTA under capless and PECVD Si3N4-capped conditions will be compared. It will be demonstrated that a remarkable improvement (&gt; 20 %) both in carrier activation and as well mobility can be achieved by co-implanting low doses (&lt; 1013 cm−2 of Al+ into n-dopant (including Si, Se and Te) implanted GaAs and subsequently annealing the material under capless RTA conditions. The maximum improvement in the electrical results with Al+ co-implants occurs for doses (e.g. &lt; 1013 cm−2 for 30 keV Si+) which are used for fabricating shallow channels for submicron GaAs MESFETs. Complex dopant-annealing environment interactions during a buried p layer formation (using either Mg+ or Be+) will be discussed.

GaAs heterojunction bipolar transistor device and IC technology for high-performance analog and microwave applications

GaAs-AlGaAs n-p-n heterojunction bipolar transistor (GaAs HBT) technology and its application to analog and microwave functions for high-performance military and commercial systems are discussed. In many applications the GaAs HBT offers key advantages over the alternative advanced silicon bipolar and III-V compound field-effect-transistor (FET) approaches. TRW's GaAs HBT device and IC fabrication process, basic HBT DC and RF performance, examples of applications, and technology qualification work are presented and serve as a basis for addressing general capability issues. A related 3- mu m emitter-up, self-aligned HBT IC process provides excellent DC and RF performance, with simultaneous gain-bandwidth product, f/sub T/, and maximum frequency of oscillation, f/sub max/, of approximately 20-40 GHz and DC current gain beta approximately=50-100 at useful collector current densities approximately=3-10 kA/cm/sup 2/, early voltage approximately=500-1000 V, and MSI-LSI integration levels. These capabilities facilitate versatile DC-20-GHz analog/microwave as well as 3-6 Gb/s digital applications, 2-3 G sample/s A/D conversion, and single-chip multifunctions with producibility. >

Onboard large-scale monolithic IC switch matrix for multibeam communications satellites

For future high-capacity multibeam communications satellite services, a large-scale switch matrix, in which a large number of switch elements are incorporated, is necessary and the miniaturization of each element is required. Monolithic IC technology is useful for miniaturization of such a large-scale switch matrix. In this paper, newly developed switch matrix using monolithic GaAs IC technology has presented. As the switch matrix element, monolithic switch module which includes two 2 × 2 switch ICs and two driver ICs has been developed. A manufactured 16 × 16 switch matrix using the monolithic switch modules achieves high isolation greater than 40 dB and very fast switching time of <50 ns. Using monolithic switch modules, the switch matrix size has been reduced to about one-third that of the hybrid IC type without degradation of performances.

The Future Impact of GaAs Digital IC's

A review of digital GaAs IC technology and an assessment of its future impact on gigabit signal processing is presented. High-speed signal processing and computers will require MSI-complexity interface circuits capable of 1-10 GHz clock frequencies and LSI-complexity digital circuits operating in the 0.2-5 GHz range at tens of microwatts per gate. A wide range of applications exists for frequency counters, multiplexers, A/D converters, FFT's, microprocessors, and memories that operate at speeds significantly higher than on presently available circuits. Issues related to high-speed IC design such as power dissipation, packing density, capacitance effects, design rules, and intra- and interchip propagation delays are discussed.

Heat treatment induced redistribution of vanadium in semi-insulating GaAs:V

The redistribution and diffusion of vanadium in V-doped high resistivity bulk as-grown GaAs, in V-doped GaAs ion implanted with V, and in high purity epitaxial layers grown on top of V-doped substrates upon various thermal annealing processes are compared to that of Cr using secondary ion mass spectrometry. The thermal processes studied are typical for GaAs IC technology. V diffuses by one order of magnitude less than Cr in all cases investigated. Thus, from thermal stability point of view V-doped GaAs substrates should be superior to Cr-doped ones and probably also to the present so-called ‘‘undoped’’ ones containing 1016 cm−3 EL2 compensators.

GaAs Analog to Digital Converter and Memory IC's for Ultra High Speed Transient Recording

The excellent electron dynamical properties of gallium arsenide enable GaAs devices to achieve high speed performance levels many times those of corresponding silicon devices. These device performance advantages carry over into integrated circuit technologies as well, aided significantly by the fact that GaAs substrate material is available in semi-insulating (>108?cm) form for very low parasitics in monolithic integrated circuits. This has led to the achievement of logic delays as low as 12.8ps at 77°K or 16.8ps at 300°K in the more exotic GaAs IC approaches. In the standard 1?m gate length, planar MESFET GaAs circuits, ring oscillator delays of ?d=52ps at PD=1mw/gate have been demonstrated, increasing to ?d=70ps at PD=2mw/gate in MSI flip flop circuits (standard ftoggle=1/5?d type-D flip flops toggle up to nearly 3 GHz). The planar ion implanted GaAs MESFET circuits have been fabricated in circuit complexities up to 1008 logic gates, with NOR gate delays as low as 150ps obtained in these LSI chips (e.g., a 35?d multiply time of 5.25ns in 8×8 bit latched parallel multiplier circuits). These 1?m gate length MESFET circuits have been fabricated on up to 3? diameter GaAs wafers using the same type of DSW optical lithography used for silicon VLSI, which is considered ample evidence that this GaAs IC technology can be cost-effective and is ready for commercialization. This paper focuses on the application of this MESFET GaAs IC technology for the types of digital memory and analog to digital converter circuits required to implement ultra high speed transient recorders.

GaAs MESFET ICs for gigabit logic applications

This paper gives an overview of the basic concepts used in the design and fabrication of gallium arsenide MESFET integrated circuits intended for gigabit logic applications. The present status of speed-power performances, packing densities, and integration levels is presented on the basis of some MSI and LSI MESFET IC realizations made possible by the principal GaAs logic approaches to date. Finally, the potential field of application and future trends of GaAs IC technology are assessed.

Assessment of Point Defects and Impurities in Semi-Insulating GaAs

Under post ion-implantation annealing treatments, semi-insulating GaAs wafers may convert to n-type or p-type. A review of the effects responsible for that conversion, and, more generally, for the influence of substrates on the properties of implanted layers is presented. These effects are related to the exodiffusion properties of shallow and deep impurities and point defects. The electrical properties of the most important of them are reminded, together with the physical phenomena which control their incorporation in Bridgman and LEC ingots. The spatial distribution of impurities and defects in these ingots is also discussed from the point of view of the quality requirements of semi-insulating wafers for the GaAs IC's technology.

MSI High-Speed Low-Power GaAs Integrated Circuits Using Schottky Diode FET Logic

A new planar high-density (10/sup -3/ mm/sup 2//gate) GaAs IC technology has been used for fabricating MSI digital circuits containing up to 75 gates/chip. These digital circuits have potential application for gigabit microwave data transmission and processor systems. The circuits consist of Schottky diode FET logic NOR gates, which have provided propagation delays in the 75-200-ps range with dynamic switching energies as low as 27 fJ/gate on ring oscillator structures. Power dissipation levels are compatible with future LSI/VLSI extensions. Operation of D flip-flops (DFF) as binary ripple dividers (/spl divide/2-/spl divide/8) was achieved at 1.9-GHz clock rates, and an 8:1 full-data multiplexer and 1:8 data demultiplexer were demonstrated at 1.1-GHz clock rates. This corresponds to equivalent propagation delays in the 100-175-ps range for these MSI circuits. Finally, a 3x3 parallel multiplier containing 75 gates functioned with a propagation delay of 172 ps/gate and with average gate power dissipations of as low as 0.42 mW/gate.

Foreword, May 1980

The next generation of microwave digital systems will require much higher clock frequencies to increase computational speed. Both military and commercial electronics have applications for digital communications with multigigabit-per-second data rates, multi-phase-shift-keyed modulation/demodulation, time multiplexing, frequency division, counting, A/D converters, memories, and frequency and waveform synthesis. During the last several years, significant progress has been made in raising the operating speed of digital microcircuits above the 1-GHz/s level. Advances in silicon IC technology will generate some limited speed improvements, but GaAs IC technology offers a two- to six-times speed improvement for the immediate future and Josephson junction technology projects another two- to three-times speed improvement for the intermediate future.

MSI High Speed Low Power GaAs Integrated Circuits

A new planar, high density (10-3 mm2/gate) GaAs IC technology has been used for fabricating MSI digital circuits containing up to 75 gates per chip. These circuits consist of Schottky diode FET logic NOR gates, which have provided propagation delays in the 80–200 ps range with dynamic switching energies as low as 27 fJ/gate on ring oscillator structures. Power dissipation levels are compatible with future LSI/VLSI extensions. Operation of D-flip flops as binary ripple dividers (\\div2 to \\div8) was achieved at 1.9 GHz clock rates, and an 8: 1 full data multiplexer and 1: 8 data demultiplexer were demonstrated at 1.1 GHz clock rates. This corresponds to equivalent propagation delays in the 100 to 175 ps range for these MSI circuits. Finally, a 3×3 parallel multiplier containing 75 gates functioned with a propagation delay of 172 ps/gate and with average gate power dissipations of as low as 420 µW/gate.

The prospects for ultrahigh-speed VLSI GaAs digital logic

Recent advances in the state of GaAs integrated circuit fabrication technology have made possible the demonstration of ultrahigh performance ( \tau_{d} \sim 100 ps) GaAs digital IC's with up to 64 gate MSI circuit complexities and with gate areas and power dissipations sufficiently low to make VLSI circuits achievable. It is the purpose of this paper to evaluate, based on the current state of GaAs IC technology and the fundamental device physics involved, the prospects of achieving an ultrahigh-speed VLSI GaAs IC technology. The paper includes a performance comparison analysis of Si and GaAs FET's and switching circuits which indicates that, for equivalent speed-power product operation, GaAs IC's should be about six times faster than Si IC's. The state of the art in GaAs IC fabrication and logic circuit approaches is reviewed, with particular emphasis on those approaches which are LSI/VLSI compatible in power and density. The experimental performance results are compared for the leading GaAs logic circuit approaches, both for simple ring oscillators and for more complex sequential logic circuits (which have demonstrated equivalent gate delays as low as \tau_{d} = 110 ps).

The prospects for ultrahigh-speed VLSI GaAs digital logic

Recent advances of GaAs integrated circuit fabrication technology have made possible the demonstration of ultrahigh performance GaAs digital ICs with up to 64 gate MSI circuit complexities and with gate areas and power dissipations sufficiently low to make VLSI circuits achievable. The authors evaluate, based on the current state of GaAs IC technology and the fundamental device physics involved, the prospects of achieving an ultrahigh-speed VLSI GaAs IC technology. GaAs IC fabrication and logic circuit approaches is reviewed. The experimental performance results are compared for the leading GaAs logic circuit approaches, both for simple ring oscillators and for more complex sequential logic circuits.

MA-4 the prospects for ultra-high speed VLSI GaAs digital logic

Recent advances in the state of GaAs integrated circuit fabrication technology have made possible the demonstration of ultrahigh performance ( \tau_{d} \sim 100 ps) GaAs digital IC's with up to 64 gate MSI circuit complexities and with gate areas and power dissipations sufficiently low to make VLSI circuits achievable. It is the purpose of this paper to evaluate, based on the current state of GaAs IC technology and the fundamental device physics involved, the prospects of achieving an ultrahigh-speed VLSI GaAs IC technology. The paper includes a performance comparison analysis of Si and GaAs FET's and switching circuits which indicates that, for equivalent speed-power product operation, GaAs IC's should be about six times faster than Si IC's. The state of the art in GaAs IC fabrication and logic circuit approaches is reviewed, with particular emphasis on those approaches which are LSI/VLSI compatible in power and density. The experimental performance results are compared for the leading GaAs logic circuit approaches, both for simple ring oscillators and for more complex sequential logic circuits (which have demonstrated equivalent gate delays as low as \tau_{d} = 110 ps).