Metal problems in plastic encapsulated integrated circuits

The long-term reliability of plastic encapsulated integrated circuits in humid environments is ultimately limited by the effects of entering moisture. Degradation of device characteristics may be acceptable in some types of circuits, but catastrophic failures ("opens" and "shorts") are certainly not acceptable. Catastrophic failures can occur in a) the metalization used on the silicon chip itself, b) the internal wires, beam leads or frames, and c) the interfaces between these parts (and others) used in making a complete package. Entry of moisture permits electrochemical corrosion or deplating and replating of metals. This occurs under operating conditions, accelerated by externally applied potentials, and also in the unoperated condition due to EMFs produced by couples between dissimilar metals or by built-in potentials of p-n junctions. Choice of metal systems, platings, and passivation geometries determine the useful life and modes of failure of plastic encapsulated integrated circuits exposed to moisture.     

Well-posed nonlinear problems in integrated circuits modeling

In this paper we study the problem (E) + (BC) + (IC) (see below) which represents a model for integrated circuits. We assume that the distributed parametersr(x) andc(x) are nonconstant, dielectric leakages depend on thex-coordinate as well as the voltage level, while the interconnecting multiport is nonlinear and possibly multivalued.     

High-voltage technology offers new solutions for interface integrated circuits

A BIMOS IC technology improving the design of interface circuits that require either high-voltage (up to 120 V) of current (up to a few amperes per output) has been developed. Both bipolar and MOS complementary components are processed together on the same chip for low- and high-voltage applications. Various BIMOS power interface circuits are now in production, e.g., a motor driver, a high-voltage plasma display driver, and a printer head driver. This paper describes the BIMOS technology and the characteristics of its components. As applications, two circuits are presented: the UEB 4732 (plasma display driver) with complementary MOS push-pull output stages (120 V), and the UAA 2081 (stepper motor driver) with power bipolar transistors (1 A per output). Both circuits have a logical part designed with low-voltage CMOS (5-12 V).     

Device mismatch and tradeoffs in the design of analog circuits

Random device mismatch plays an important role in the design of accurate analog circuits. Models for the matching of MOS and bipolar devices from open literature show that matching improves with increasing device area. As a result, accuracy requirements impose a minimal device area and this paper explores the impact of this constraint on the performance of general analog circuits. It results in a fixed bandwidth-accuracy-power tradeoff which is set by technology constants. This tradeoff is independent of bias point for bipolar circuits whereas for MOS circuits some bias point optimizations are possible. The performance limitations imposed by matching are compared to the limits imposed by thermal noise. For MOS circuits the power constraints due to matching are several orders of magnitude higher than for thermal noise. For the bipolar case the constraints due to noise and matching are of comparable order of magnitude. The impact of technology scaling on the conclusions of this work are briefly explored.     

Millimeter-wave integrated circuits

Monolithic millimeter-wave integrated circuits have been designed and fabricated on semi-insulating GaAs substrates using microstrip transmission lines. Circuits using hybrid techniques have also been constructed on quartz and ceramics. This paper shows that microstrip-line integrated circuits are feasible at millimeter-wave frequencies. Circuit functions have been constructed and tested in the 25- to 100-GHz range. The loss in microstrip line on semi-insulating GaAs was found to be less than 0.3 dB/λ. Couplers from waveguide to microstrip have been made with transmission losses less than 0.5 dB. Monolithic integrated detectors showed 5-dB better sensitivity than a 1N53 diode in a philips detector mount. Monolithic diodes delivered 1.5 mW at 28 GHz. The results are encouraging and a fully monolithic integrated receiver is under development.     

Power estimation methods for analog circuits for architecturalexploration of integrated systems

This paper describes methods for analog-power estimation and applies them practically to two different classes of analog circuits. Such power estimators, which return a power estimate given only a block's specification values without knowing its detailed circuit implementation, are valuable components for architectural exploration tools and hence interesting for high-level system designers. As an illustration, two estimators are presented: one for high-speed analog-to-digital converters (ADCs) and one for analog-continuous time filters. The ADC power estimator is a technology scalable closed formula and yields first-order results within an accuracy factor of about 2.2 for the whole class of high-speed Nyquist-rate ADCs. The filter-power estimator is of a more complex nature. It uses a crude filter synthesis, in combination with operational transconductor amplifier behavioral models to generate accurate results as well, but restricted to certain filter implementations     

Microwave and millimeter-wave integrated circuits

This historical review is divided into three sections: microwave integrated circuits (MICs), monolithic microwave integrated circuits (MMICs), and MIC and millimeter-wave integrated-circuit applications     

Design of integrated circuits: directions and challenges

Several of the dimensions of IC CAE technology are discussed, focusing on two design styles: custom design, used for commodity products such as DRAMs, microprocessors, etc., where large volume production is planned and area reduction and performance maximization can be expected to return large dividends; and the design of application-specific integrated circuits (ASICs), utilizing either very regular, prepatterned silicon arrays customized at the interconnect level or predesigned, parameterized libraries of cells that are usually arranged in rows and interconnected. The design research that will be required in order to attain the objectives of highly automated design systems and shorter product design cycles for integrated circuits are outlined. Metrics for design system performance are discussed     

Photonic integrated circuits: A technology update

A photonic integrated circuit (PIC) monolithically integrates many optical components, such as lasers, modulators, detectors, attenuators, multiplexers, demultiplexers, and amplifiers, into a single photonic substrate and device. PICs thus provide important benefits for optical transmission systems, including packaging consolidation, increased system density, reduced power consumption, reduction in fiber couplings, and improved reliability.     

Elevated electrode integrated circuits

We have developed a new device structure for a bipolar integrated circuit with a propagation delay time of 85 ps/gate and a speed-power product of 0.19 pJ. The remarkable feature of this integrated circuit is its overhanging structure of elevated emitter and collector electrodes, resistors, and interconnections. This paper describes the structure, fabrication process, and performance of this integrated circuit.     

GaAs integrated microwave circuits

GaAs has many desirable features that make it most useful for microwave and millimeter-wave integrated circuits. The process of selective epitaxial depositions of high purity single-crystal GaAs with various doping concentrations into semi-insulating GaAs substrates has been developed. These high-resistivity substrates (>10⁶ohm.cm) provide the electrical isolation between devices, eliminating the difficulties and deficiencies normally encountered in trying to obtain isolation with dielectrics, back-etching, p-n junctions, etc. This monolithic approach to integrated-circuits thus allows for improved microwave pedormance from the devices since parasitics are reduced to a minimum. Planar Gunn oscillators and Schottky barrier diodes have been fabricated for use in a completely monolithic integrated millimeter wave (94 GHz) receiving front end. The Gunn oscillators are made in a sandwich-type structure of three selective deposits whose carrier concentrations are approximately 10¹⁸-10¹⁵-10¹⁸cm^-3. The Schottky diodes consist of two deposits with concentrations of 10¹⁸and 10¹⁷cm^-3. The Schottky contact is formed by evaporating Mo-Au onto the 10¹⁷cm^-3deposits; all ohmic contacts are on the surface and are alloyed to the N⁺regions.     

Elevated electrode integrated circuits

The authors developed a new device structure for a bipolar integrated circuit with a propagation delay time of 85 ps/gate and a speed-power product of 0.19 pJ. The remarkable feature of this integrated circuit is its overhanging structure of elevated emitter and collector electrodes, resistors, and interconnections. This article describes the structure, fabrication process, and performance of this integrated circuit.     

Silicon-on-insulator power integrated circuits

A power integrated circuit process has been developed, based on silicon-on-insulator, which allows intelligent CMOS control circuitry to be placed alongside integrated high-voltage power devices. A breakdown voltage of 335 V has been obtained by using a silicon layer of 4 μm thickness together with a buried oxide layer of 3 μm thickness. The respective LDMOS specific on-resistance and LIGBT on-state voltage for this breakdown voltage were 148 mΩ cm² and 3.9 V, respectively.     

Making GaAs integrated circuits

Digital gallium arsenide (GaAs) integrated circuits offer prospects for high-performance electronics, particularly for increased speed and radiation hardness. Prototype GaAs devices fabricated in technologies ranging from ion-implanted metal semiconductor field-effect transistors (MESFETs) and junction field-effect transistors (JFETs) to epitaxial heterostructures, such as high-electron-mobility transistors (HEMTs) and heterojunction bipolar transistors (HBTs), have demonstrated these advantages. While these GaAs technologies share many common fabrication features, the unique characteristics of each and GaAs materials present significant manufacturing challenges. It is argues that to produce real integrated circuits (ICs) for system applications, the disciplines and rigors of a production environment as well as the innovations of research and development are required     

Comparing MOS and bipolar integrated circuits

In terms of speed and speed/power performance, bipolar integrated circuits are superior to metal-oxide-semiconductor integrated circuits. This superiority is based on the high transconductance inherent in bipolar transistors and is technology-independent. For the MOS case, transconductance is highly technology-dependent, and hence the performance difference will probably diminish in the future. Comparisons of the two technologies in their mid-1966 forms are made; the bipolar performance advantage in most cases is between 10 and 100. MOS integrated circuits have an area-per-function advantage ratio of about 5 for equivalent-function circuits, but a ratio of between 5 and 10 when circuits exploiting the unique MOS properties are considered. In addition, MOS processing is simpler than bipolar processing by approximately 40 percent.