Showing papers by "Motorola published in 1969"

Electromigration—A brief survey and some recent results

Abstract: Recently, electromigration has been identified as a potential wear-out failure mode for semiconductor devices employing metal film conductors of inadequate cross-sectional area. A brief survey of electromigration indicates that although the effect has been known for several decades, a great deal of the processes involved is still unknown, especially for complex metals and solute ions. Earlier design equations are improved to account for conductor film cross-sectional area as well as film structure, film temperature, and current density. Design curves are presented which permit the construction of high reliability "infinite life" aluminum conductors for specific conditions of maximum current and temperature stress expected in use. It is also shown that positive gradients, in terms of electron flow, of temperature, current density, or ion diffusion coefficient foreshorten conductor life because they present regions where vacancies condense to form voids.

Multiproject Scheduling with Limited Resources: A Zero-One Programming Approach

Abstract: A zero-one 0-1 linear programming formulation of multiproject and job-shop scheduling problems is presented that is more general and computationally tractable than other known formulations. It can accommodate a wide range of real-world situations including multiple resource constraints, due dates, job splitting, resource, substitutability, and concurrency and nonconcurrency of job performance requirements. Three possible objective functions are discussed; minimizing total throughput time for all projects: minimizing the time by which all projects are completed i.e., minimizing makespan; and minimizing total lateness or lateness penalty for all projects.

Electromigration failure modes in aluminum metallization for semiconductor devices

Abstract: Two wear-out type failure modes involving aluminum metallization for semiconductor devices are described. Both modes involve mass transport by momentum exchange between conducting electrons and metal ions. The first failure mode is the formation of an electrically open circuit due to the condensation of vacancies in the aluminum to form voids. The second is the formation of etch pits into silicon by the dissolution of silicon into aluminum, and the transport of the solute ions down the aluminum conductor away from the silicon-aluminum interface by electron wind forces. The process continues until an etch pit grows into the silicon to a depth sufficient to short out an underlying junction.

Automatic vehicle monitoring identification location alarm and voice communications system

Abstract: In a computer-controlled bus-monitoring system, each of the buses in the system is provided with a two-way radio for communication with the control center on either a voice channel or a data channel. In addition, each bus includes a second receiver for receiving signals from signpost transmitters located along the route, with the signpost information being stored in a temporary storage unit in the bus. The computer continually controls interrogation of all of the buses in the system on a data channel, with the buses automatically replying with the stored signpost location plus the time elapsed since that signpost location was stored in the bus. Deviations from schedule are displayed on a control console at the control center. The bus may be alerted to reply on a voice channel by a special code sent over the data channel with selective calling of the particular bus being provided, and a provision also is made for alerting the control center of an emergency on the bus by automatic data transmission from the bus over the voice channel.

Thermal Cycling and Surface Reconstruction in Aluminum Thin Films

Abstract: The appearance of "annealing hillocks" on heat treated aluminum films has been previously reported Thin films of Al, deposited on passivated wafers, were annealed for various lengths of time in the temperature range 200°–500°C The effects of grain size, alloying and surface passivation on hillock formation, were studied It is the purpose of this report to summarize the effect of thermal cycling on similar films and to show in more detail the size and appearance of the hillocks Aluminum was deposited on oxidized silicon substrates in a vacuum of about 10−8 Torr Grain sizes at the deposition temperature were on the order of <1μ, 1μ, and 5μ Manual cycling was carried out between a hot stage in N2 and a room temperature heat sink Control samples were annealed (uncycled) for equivalent times‐at‐temperature Photomicrographs of the surface at its various stages of reconstruction were taken and scanning electron micrographs provided a more detailed view of individual hillocks and their surroundings At the higher temperatures (425°C) thermal cycling increases the number of hillocks by factors of 2 or 3, with the typical hillock density estimated to be approximately 106/cm2 Cycling also increases the size of the protrusions, and hillocks as high as 35μ have been observed growing out of a 07μ film Experiments employing glass passivation confirm earlier results that surface reconstruction can be eliminated

Method of packaging an optoelectrical device

Abstract: In packaging an optoelectrical device, liquid silicone which can be cured to become a transparent flexible polymer substance having an index of refraction close to that of a solid transparent cover plate is disposed between the light sensitive side of the device and a surface of the cover plate and in good optical coupling therewith.

Metallization systems for silicon integrated circuits

Abstract: An investigation into single and composite layered metallization systems is described with respect to their limitations, possible failure mechanisms, and problems encountered in fabrication. Systems investigated include metals such as chromium, titanium, tungsten, and molybdenum in conjunction with gold. Comparisons are made to conventional aluminum with respect to ohmic contact to silicon, metallurgical reactions, behavior in adverse environmental conditions, method of deposition, and processing difficulties.

Clamping heat sink

Abstract: A CLIP-ON HEAT SINK FOR USE WITH THERMO-PAD TYPE TRANSISTORS IS MADE IN THE FORM OF A UNITARY PIECE OF HEATCONDUCTIVE, BLACK-ANODIZED SPRING ALUMINUM FOLDED ON ITSELF APPROXIMATELY AT ITS CENTER TO PROVIDE AN OPENING WHICH FITS OVER THE TRANSISTOR AND TIGHTLY ENGAGES THE TRANSISTOR IN HEAT CONDUCTIVE RELATIONSHIP. THE PORTIONS OF THE SPRING MATERIAL EXTENDING AWAY FROM THE BIGHT FORMED BY THE FOLD CONVERGE TO FORM CLAMPING JAWS, WITH THE MATERIAL AT THE ENDS OF THE JAWS BEING BENT BACK TO EXTEND IN SUBSTANTIALLY PARALLEL PLANES ALONG EACH OF THE CONVERGING PORTIONS BEYOND THE BIGHT FORMED BY THE FOLD AT THE CENTER OF THE SPRING TO PROVIDE A PAIR OF GRIPPING EXTENSIONS WHICH CAN BE RELATIVELY MOVED TOWARD AND AWAY FROM ONE ANOTHER TO SPREAD THE JAWS APART TO ENABLE PLACEMENT OF THE HEAT SINK CLIP OVER THE TRANSISTOR.

Characteristics of two-region saturation phenomena

Abstract: Diffused base bipolar transistors, especially high-voltage types, often exhibit two pronounced saturation regions. This paper elucidates the qualitative and quantitative features of this behavior which is due to conductivity modulation of the lightly doped collector region. The transport equations for ambipolar conduction in the collector region are solved with a minimum of simplifying assumptions. It is shown how this portion of the solution explains the general features of the phenomenon. A complete solution for the collector V-I characteristics depends on an explicit knowledge of the recombination statistics in both the base and collector regions. A simple case is considered to demonstrate the detailed dependence of the phenomena on the physical structure. Design tradeoffs involved in the control of the V-I characteristics are discussed in the light of the results obtained from the analysis.

Constant-energy ignition systems

Abstract: A constant-energy ignition system controlled by a solid-state circuit having an emitter-follower current sensing unit in accordance with the current flowing through the ignition coil. A flywheel diode is connected between the coil and ground to maintain current through the coil just prior to ignition. Semiconductor switches are connected to the coil which are turned on and off by the current sensing unit to increase current through the coil a predetermined magnitude. Then the coil current source is turned off requiring the flywheel diode to permit current to flow through the coil for maintaining a substantially constant energy in the coil irrespective of engine speed. When the coil current amplitude has decreased to a second predetermined amplitude, coil current is again supplied through the switch.

Dielectric isolated integrated circuit substrate processes

Abstract: Dielectric isolation has proven effective in raising inter-device breakdown voltages, lowering parasitic capacitances, and increasing resistance to radiation damage. The fabrication of a dielectric-isolated substrate, prior to diffusions, requires adequate control of the thickness of the epitaxial layer, of crowning and warpage, and of a necessarily smooth, damage-free surface. The mere juxtaposition of three or more layers of different materials, even before diffusion-induced strains, creates special problems because of coefficient-of-expansion mismatches. In addition, the substrates must pass through subsequent diffusion cycles and permit the fabrication of transistors with characteristics as good as (or better than) those made on p-n junction isolated substrates. There are three major methods of using silicon dioxide as a dielectric to separate active areas of an integrated circuit: 1) shape-back to the channels of a wafer which has had channels etched out and filled with polycrystalline silicon; 2) etch out and fill in with single crystal on an n+wafer which has already had isolation moats created; and 3) growth of polycrystalline silicon prior to etching the isolating channels. This paper describes and compares these methods.

Piezoelectric Semiconductor Acoustic Delay Lines

Abstract: The delay of signals for microsecond time periods in monolithic structures using piezoelectric semiconductors is described. Thin resistive regions were formed by the diffusion of compensating impurities in semiconducting crystals of ZnO, CdS, CdSe, and GaAs and used as transducers for the excitation and detection of acoustic waves in the 30-MHz to 1.0-GHZ region. Time delays from 200 ns to 5.0 /spl mu/s were achieved using simple acoustic transmission structures. Insertion loss values less than 10 dB were achieved in ZnO for microsecond delays up to 600 MHz. Frequency-tuned bandwidths of 70 to 90 percent were obtained. The frequency-loss characteristics of the delay structures could be quantitatively related to a simple theoretical model. The performance characteristics of representative matched and packaged acoustic delay lines is described.

A Cr&#8212;Ag&#8212;Au metalization system

Abstract: A comprehensive study of a Cr-Ag-Au metalization system, as well as a comparison with an aluminum system, is described. The Cr-Ag-Au metalization system, which can be deposited in a conventional evaporator with relatively little increase in processing complexity, has the desirable characteristics of aluminum metalization. It can be patterned more easily than equivalent thicknesses of aluminum. The Cr-Ag-Au has excellent storage characteristics at 300°C and has a much longer mean time to failure than does aluminum under high current density-high temperature stress. In addition, measurements show that with the use of an enhancement diffusion the Cr-Ag-Au produces as good as or better contact to p- and n-type silicon than does aluminum. Finally, the absence of significant metalization-oxide interaction makes Cr-Ag-Au useful for MOS devices and the ease with which contact is made between layers of this metalization indicates a number of applications for Cr-Ag-Au in multilayered devices.

Resilient mounting support for plurality of electrical devices,such as piezoelectric crystals

Abstract: Resilient mounting support for electrical devices, such as piezoelectric crystals, for mounting the same on the chassis of electrical apparatus, such as a radio transmitter and/or receiver. The support includes a block of resilient material having cavities therein for receiving the containers for the devices, and integral mounting tabs for securing the block to the chassis. The block may be positioned in an opening in the chassis and the mounting tabs may have projections extending in other openings with interlocking projections to hold the same in position. The support may be formed of transparent silicone rubber to protect the devices against shock and vibration and to permit inspection of identifications on the containers through the mounting support.

A self-compensated monolithic operational amplifier with low input current and high slew rate

Abstract: A monolithic operational amplifier which achieves a gain of 150,000, 5 nA input current and a 4 V/μs slew rate will be described. The amplifier incorporates high β input transistors, a novel PNP-NPN composite and an MOS compensation capacitor.

Threaded fastener captivating device

Abstract: A SNAP-IN SCREW CAPTIVATING DEVICE IS INSERTED INTO A HOLE IN SHEET MATERIAL TO BE SECURED BY THE SCREW AND IS FORMED OF RESILIENT MATERIAL IN THE GENERAL CONFIGURATION OF A SLOTTED CYLINDER HAVING A SCREW HEAD RECEIVING CHAMBER. THE CAPTIVATING DEVICE FITS WITHIN THE HOLE IN THE SHEET MATERIAL AND EXPANDS TO ENGAGE THE E EDGES OF THE HOLE. THE UPPER EDGES OF THE CHAMBER BEND INWARDLY A SHORT DISTANCE INTO THE CHAMBER TO FORM A LEDGE, AND THE SCREW IS PUSHED PAST THIS SLOTTED LEDGE CAMMING IT OUTWARDLY TO ALLOW THE HEAD TO PASS, WHEREUPON THE CHAMBER RESUMES ITS ORIGINAL POSITION. THE CHAMBER MAY BE EXTENDED TO PERMIT BACKING OUT OF THE SCREW FROM THE THREAD AND TO PROVIDE SPACE FOR A SNAP BUTTON TO BE PLACED ON TOP OF THE SCREW HEAD. WHEN THE BUTTON IS IN PLACE, THE BUTTON ALSO IS CAPTIVATED BY THE ACTION OF THE CAPTIVATING DEVICE HOLDING THE BUTTON IN PLACE.

Controlled hysteresis trigger circuit

Abstract: A stable electronic trigger circuit having a predetermined DC hysteresis in the operation of the circuit is formed as an integrated circuit including three NPN transistors: an input transistor and a pair of output transistors connected in a Darlington amplifier configuration directly driven from the collector of the input transistor. Operating potential for the trigger circuit is obtained from the voltage drop across a string of series connected transistor diodes, and the input transistor has collector and emitter resistors connected to it, with the collector resistor having an impedance many times that of the emitter resistor. The switching levels of the trigger circuit are determined by the ratio of the collector and emitter resistors in the input transistor circuit and/or by the base-emitter voltage drops across the transistors.

A stereophonic receiver muting means with substitution of a dc circuit for an ac circuit

Abstract: A silicon monolithic integrated circuit stereo multiplex receiver includes a gated symmetrical demodulator for providing the desired left and right audio output signals. A second demodulator is supplied with the same composite input signal supplied to the first demodulator, but substantially attenuated, with the second demodulator providing output signals 180* out of phase with the signal supplied by the first demodulator; and the outputs of the two demodulators are combined so that the crosstalk components are effectively eliminated. A provision also is made for interstation audio muting and for stereo muting by the direct substitution of equivalent DC loads for the AC amplifiers normally responding to the signals, so that transientless muting is achieved. In order to control the muting and to provide a driver for the stereo indicator lamp, trigger circuits having predetermined hysteresis of operation are formed as part of the integrated circuit. Improved symmetrical drive for the demodulator circuit is obtained by feeding the 19 k.c. pilot signal to the doubler circuit across a string of diodes which logarithmically compress signals that would tend to overdrive the doubler transistor amplifier. A filter at the emitter of the doubler amplifier establishes a DC level which is used to fire the indicator lamp trigger circuit to indicate stereo signals are being received and also serves to self-bias the doubler amplifier to further prevent its being overdriven.

Fixed gradient liquid epitaxy apparatus

Abstract: A method and apparatus for growing an epitaxial layer on a semiconductor substrate by the use of liquid phase transport and a fixed temperature gradient are disclosed. The apparatus consists of a lower block and a movable upper block which slides across the lower block. The lower block has one or more recessed portions suitable for holding one or more semiconductor wafers, such as gallium arsenide, on which an epitaxial layer is desired. The upper block similarly has one or more centerbores with slideable pistons disposed therein. A solvent such as gallium and a semiconductor source material such as a gallium arsenide wafer are located in the centerbore below the piston. Growth of the epitaxial layer on the substrate occurs at an elevated temperature when the centerbore of the upper block is in registration with the recessed portion of the lower block and the lower block is at a temperature that is slightly lower than the temperature of the upper block. The method includes the step of sliding the blocks so that the centerbore is out of registration with the recessed portion of the lower block thereby removing the solvent from the surface of the epitaxial layer to terminate the epitaxial growth.

Spark duration for capacitor discharge ignition systems

Abstract: A capacitor discharge ignition system wherein an energy storage capacitor is charged to a relatively high voltage and synchronously discharged into the primary winding of an ignition coil to develop a high-energy short-time duration spark discharge at the secondary winding of the ignition coil, and a circuit is provided for increasing the time duration of the spark discharge beyond that normally obtained from the capacitor discharge system to improve the fuel-igniting properties of the spark.

Bonding system for semiconductor device

Abstract: A method of bonding a semiconductor device to a metal substrate involving depositing a gold solder preform onto the device and coating the metal substrate with a first layer of gold, a second layer of silver and a third layer of gold. The device is bonded to the metal substrate by heating the substrate to an elevated temperature and placing the gold preform on top of the third gold layer of the substrate.

Digital communication synchronization system including synchronization signal termination recognition means

Abstract: A shift register in a receiving unit uses a feedback to develop a digital code and the digital code is compared with an incoming digital code used to synchronize a digital communication signal. Initially the shift register is fed the incoming digital code signal. If the received and generated signals are in agreement an output signal is added in an integrator for each agreement. If the signals do not agree the output signal is subtracted from the signal stored in the integrator. When the signal stored in the integrator reaches a predetermined level a switching action occurs which connects the feedback output of the shift register to the input of the shift register so that the code is selfgenerating and errors in the incoming code will not be coupled into the shift register.

Reduced forward voltage drop rectifying circuit

Abstract: A dynamic rectifying device uses a transistor biased to saturation as the rectifying element. The lower voltage drop between collector and emitter of a saturated transistor (as compared with the diode voltage drop) provides increased rectifying efficiency and better clamping action. The circuit includes a bias network using the input alternating current signal to develop the proper bias voltage for the circuit.

Tone-controlled speech scrambler

Abstract: A speech-coding or scrambling system which operates by changing a speech signal by means of an inverter signal, also incorporates a tone signal outside of the speech frequency band to inform the receiver that the speech is being coded. Upon the receipt of the tone signal the receiver automatically operates to decode the received signal.

Method for ultrasonically welding using a varying welding force

Abstract: An improvement in ultrasonic welding is effected by progressively increasing the welding force and then applying the ultrasonic energy so that a portion of the ultrasonic welding period occurs during the welding force range when optimum ultrasonic welding conditions exist; an ideal welding force, for this application being defined as the force applied to the parts to be joined by a welding tip or other means of applying ultrasonic energy, so that the faces to be welded are pressed together at the intended location of the weld.

Color television signal demodulation system

Abstract: A silicon monolithic integrated circuit consisting of three sets of full-wave, synchronous, switched demodulators is used to demodulate the red, blue and green color signals present in a composite television signal. Each of the demodulators consists of two pairs of switching transistors with the transistors in each of the pairs being rendered alternately conductive by a reference signal derived from the reference oscillator in a color television receiver. The phase of the red and the blue reference oscillator signals are obtained in a conventional manner, and the phase for the green reference signal is obtained by adding a predetermined portion of the red and blue signals together in a resistive adder to provide the green oscillator signal. The color signals are supplied in alternate phase to the two pairs of switching transistors in each of the demodulators, and the brightness signal components are applied equally or push-push to the switching transistors of the demodulators through an input transistor for each of the demodulators. In order to provide the proper relative amounts of gain for three demodulators, the red and blue signal demodulators have shunting resistance circuits connected across the input transistor circuits; and the green demodulator has a shunt connected across equal taps on voltage dividers connected to the outputs thereof. Since the brightness signal components are balanced with respect the the shut devices, the brightness signal passes through all of the demodulators unaffected by the shunting circuits.

Ultrasonic metallic sheet-frame bonding

Abstract: In simultaneously bonding all the bonding pads of an integrated circuit chip to respective inwardly extending leads comprising parts of an unsupported metallic sheet-frame, a chip bearing the integrated circuit is positioned with its pads in contact with the ends or tips of the leads, comprising part of the frame, on a bonding post. The contacting flat tip of a bonding needle is pressed against the back of the chip to squeeze the ends of the leads and the pads together and the bonding needle is vibrated to cause rubbing motion between the tips of the leads and the bonding pads thereby to bond the ends of the leads to their respective pads. To make sure that the vibrating force is applied to the chip, the flat tip of the steel needle has a layer of soft metal such as copper deposited thereon. To make sure that the ends of the leads do not move and yet to prevent cutting through the leads, the top of the post is not serrated but is roughened as by vapor honing. The tips of the leads are thinned by the squeezing action. The honing also puts a slight curvature on the edges of the posts that are in contact with the leads, whereby a curvature is imparted to the leads at the junction of the thinned and unthinned portions thereof, whereby the leads are weakened at this junction to a lesser extent than in the prior art. The working tip of the post is made hollow to concentrate the compressive force to the area where the leads are in contact with the bonding pads, thereby requiring less pressure on the needle.

Multi-frequency receiver with automatic channel selection and priority channel monitoring

Abstract: A channel scanning and priority channel monitoring circuit for a multifrequency receiver utilizes a bistable multivibrator to control the local oscillator frequencies corresponding to the channels, with one output of the multivibrator corresponding to the priority channel. A low-frequency free-running oscillator and a pair of monostable delay circuits, having a relatively short time interval, produce pulses to change the state of the multivibrator. With no signals being detected on any of the channels, the multivibrator is controlled by the monostable delay circuits to provide a relatively rapid sequential scanning of the channels. Detection of a carrier on a nonpriority channel, however, shifts control of the bistable multivibrator to the free-running oscillator to reset the bistable multivibrator to scan the priority channel, whereupon control is returned to the monostable circuits. Provision is made for attenuating the audio output whenever a nonpriority channel is being received and for increasing the sensitivity of the squelch circuit whenever a nonpriority channel is being scanned.