World Abstracts on Microelectronics and Reliability
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5. M I C R O E L E C T R O N I C S D E S I G N A N D C O N S T R U C T I O N Silicon epitaxial growth via dichlorosilane in a barrel reactor. Y. S. CHIANG. RCA Rev. 38, 500 (December 1977). This report presents the results of the study of silicon epitaxial growth using dichlorosilane in a large vertical barrel reactor. Thickness uniformity, surface quality, and resistivity control and uniformity of the epitaxial layers were studied and optimized in terms of the operating parameters of the system. Under the experimentally defined optimal conditions, thickness uniformity in the neighborhood of + 5 % is achieved for growth rates in the range of 2 to 6/~m/min. The resistivity of undoped layers on heavily doped n + substrates is equal to or exceeds 100ohm-cm. The doping control and resistivity uniformity are more than sufficient for growth of high-voltage device structures. Surface quality comparable to that obtained via silicon tetrachloride has been achieved. Planar Zn diffusion in lnP. E. A. REZEK, P. D. WRIGHT and N. HOLONYAK,JR. Solid-St. Electron. 21,325 (1978). A procedure for achieving well-behaved planar Zn diffusion to a controllable depth in n-type InP is described. The dilute-Zn diffusion, which utilizes a Zn + Ga + P source (in an evacuated ampoule), is performed in the temperature range 650~ 700°C. The low diffusion temperatures employed assure that any previous junctions that might be prepared, such as LPE heterojunctions, are not affected by the diffusion process. The masking afforded by Si3N,~ and partial "masking," or attenuation, afforded by S i O / o n InP are demonstrated. The results obtained suggest that dilute Zn diffusion in lnP, with a significant P over-pressure, favors a substitutional diffusion mechanism that probably follows a complementary error function distribution.
cluding lift-off pattern studies, clamped-wire studies, and bond deformation versus ultrasonic vibration amplitude studies, indicate that gold ultrasonic bonding takes place primarily by means of a deformation mechanism as opposed to a heating or sliding mechanism. This is substantially the same result previously obtained from studies on the aluminum ultrasonic bonding mechanism. Further, it is shown that a deformation mechanism also holds for other forms of solid phase microelectronic bonding. Specific examples are taken from electric discharge "tweezer welds" and from thermocompression bonds. The role of contaminant removal and certain reliability aspects of ultrasonic bonding are also discussed.
High temperature thermal characteristics of microelectronic packages. GENE K. BAXTER and JAMES W. ANSLOW. IEEE Trans. Parts, Hybrids, Packa~in,q PHP-13, (4) 385 (December 1977). This paper describes results of the computer-analysis portion of a research program which was conducted to study the thermal characteristics of microcircuits in high temperature environments. A special 1C chip, bonded to an alumina chip carrier, was modeled for these simulations. It was found that thermal resistance values and thermal time constants nearly double when the chip carrier temperature is increased from 70 to 257°C. For a chip power dissipation of 1.5 W, the peak junction temperature increased from 138 to 385°C, an increase of 247°C, while the chip carrier only increased by 187°C. The thermal time constant of the junction peak temperature rise, measured relative to the chip carrier, increased from 15 to 26 ps over the same temperature range.
Improved slicing and orientation technique for I.D. sawing. JOHANNES GRANDMAand J. CHARLES HILL. Solid St. Technol. p, 40 (February 1978), A new technique for cutting gadolinium gallium garnet wafers for substrates in bubble memory devices is described. This technique should also have application to slicing other substrate materials, such as sapphire and silicon. The method extends the useful life of I.D. diamond blades by a factor of seven and increases productivity substantially while decreasing cost.
A new moisture sensor for in situ monitoring of sealed packages. MICHAEL G. KOVA(', DAVID CHLECK and PHILIP GOODMAN. Solid St. Technol. p. 35 (February 1978). A new A1203 moisture sensor fabricated on an oxidized silicon wafer is described. The sensor responds to moisture levels down to 1 ppmv and is used to nondestructively determine the water level inside sealed hybrid packages. Device performance characteristics are given. Preliminary results are reported for these devices sealed in hybrid packages at several manufacturing locations.
The ultrasonic welding mechanism as applied to aluminumand gold-wire bonding in microelectronics. GEORGE G. HARMAN and JOHN ALBERS. IEEE Trans. Parts, Hybrids, Packa,qin9 PHP-13, (4) 406 (December 1977). This paper represents a review as well as an extension of previous work concerned with the mechanism of microelectronic ultrasonic welding for both aluminum and gold wires. A series of experiments was carried out to determine the mechanism of gold-to-gold ultrasonic bonding. These experiments, in-
Ellipsometry for semiconductor process control. R. J. K UTKO. Solid St. Technol. p. 43 (February 1978). General aspects of the powerful and elegant technique of ellipsometry are described. Emphasis is on the practical utilization of this method for measuring semiconductor films. Values are given for films and substrates likely to be encountered. Also discussed are recent new developments in data conversion and instrumentation such as calculators and fully automatic ellipsometers.
6. M I C R O E L E C T R O N I C S - - C O M P O N E N T S ,
Low-cost microcomputing: The personal computer and singleboard computer revolutions. JOHN DOERR. Proc. IEEE 66, (2) 117 (February 1978). Personal computing is one of the most revolutionary applications of microprocessors; singleboard computing is another. The origins of both applications are traced and current products and services described in a tutorial fashion. Trends are forecasted and conclusions drawn about these two low-cost computing revolutions. Spurious signal generation in plastic film capacitors. JON W. BOROUGH, JOHN BURNHAM, WILLIAM J. SIMMONS and SAMMIEL. WEBSTER.IEEE Trans. Parts, Hybrids, Packaging PHP-13, (4) 402 (December 1977). Plastic film capacitors with dielectric materials such as Mylar or polycarbonate have been observed to generate spurious signals which
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appear as small spikes in capacitor voltage in the range of 10-300 #V. Such transients repeat at intervals varying from fractions of a second to years, becoming more frequent during periods of temperature change. The tendency to produce this phenomenon can persist for the normal life of the capacitor, depending on thermal and electrical stresses encountered. The effect under study is not related to dielectric breakdown or corona discharge which are due to high electric stress. The observed transients can appear at the capacitor electrodes with either polarity during application of voltage as low as zero. The source of charge and energy for this phenomenon is dielectric absorption (DA) which is history dependant relating directly to the nature of the dielectric material. Materials with high DA such as Mylar are much
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World Abstracts on Microelectronics and Reliability
more susceptible than "nonpolar" dielectrics such as polyslyrcne. 'l'hc R)llowing considerations in minimizing generation of spurious signals are discussed: (1t i2) [3) [4i
selection of materials: limitations on use conditions: preconditioning or annealing ; capacitor screening techniques.
12L puts it all together for 10-bit a-d converter chip. PAt:l, BROKAW, Electronics p. 99 (13 April 1978L Linearcompatible integrated injection logic may well become the technology of choice for fabricating high-performance monolithic analog-to-digital converters, As a bipolar process. il can produce better analog components than any metal-oxide-semiconductor process, and unlikc other forms of bipolar logic, it can compete with M O S levels of digitalcircuit density. As a result, 12L is the technology behind a new 10-bit a d converter, which is also the first chip of its kind to be frilly self-contained. Its only external needs are the appropriate power-supply voltages and a convert command. Its on-chip voltage reference and clock save the user both the bother and expense of implementing these functions offchip. Its other elements a comparator, a digital-to-analog converter, a successive-approximation register, and control logic handle the successive-approximation conversion.
Linear ! ( automatically focuses camera lens. LAVON K. COOPER, DA'¢ID I~. FULKERSON and NORMAN L. SIAUFFER. t;'h'ctronics p. 139 (27 April 1978). By comparing a fixed and a moving image on two photodetectors, focusing system based on an optolinear chip recognizes best match and produces a signal that is used to set a range-finder camera lellS.
New arrivals in the bulk storage inventory. LAURENCE AI_IMaN. Eh'ctronic.,, p. 106 (13 April 1978). Designers of mare inemories, disk tiles, and intelligent terminals should take a good hard look at today's bubble memories and chargecoupled devices. High temperature properties of solid tantalum chip capacitors. I)AVlI) (i. Tln)MPSON and SUP,ENDI~:R GUNNALA. IEEE Trails. Parts, ll ybrids, Packaging! P H P - ! 3,(4) 390 (December 1~.~77). The use of tantalum chip capacitors in conjunction with hybrid circuitry requires stable capacitor characteristics that x~ill withstand the stresses of c o m p o n e n t ' a t t a c h m e n t , testing, and circuit operations. A line of miniature tantalum chip capacitors is discussed with emphasis on materials, constructional methods, and resultant performance of the devices under environmental and operational conditions. Results of exposure It) high temperature attachment conditions are presented with details of impedance and dissipation factor characteristics as well as other traditional capacitor parameters.
lation. The effects of the substrate resistivity are considered for low. moderate and high doping concentrations It is shown that only when the channel thickness is much smaller than the oxide thickness the device saturation characteristics can be approximated by a square fnnction of the gate w)ltage. Results of small-signal calculations arc presented for both generalized and specific device structures which depict the gate voltage dependence of the gate and subslrale Iransconductance and the input capacitance paramelers for both depletion and accumuhltion mode of operations. A small signal equiwilent network model is proposed which can be used for the calculation of high-frequenc.,, device linlitations.
Operation and characterization of N-channel EPROM cells, Jetty J. BARN~;S, JEH: L. LINI}~:N and JOHN R. El)WARDS. Solid-St. Electron. 21, 521 (1978). This paper describes the operation and characterization of N-Channel, double-polysilicon gate M O S structures that may be used in an Erasable, Programmable, Read-Only Memory (EPROM). l h e trade-offs for various structures with regard to writing ability, reading ability, fabrication complexity and ease of erasure are discussed, Measurements of the device arc coinpared to the associated theory, and the sensitivity of the structure to various device parameters is also described Dense, interchangeable RUMs work with fast microprocessors. RC.BER'I GREENI!. Electronics p. 104 (30 March 1978) l'he recently introduced 2332 and 2364 read-only memories double and quadruple the density of today's 16-K devices by using an adaptation of lntel's It-MOS process. Moreover, being flmctionally compatible with each other, earlier men> burs of the same family, and the new high-performance microprocessors, they eliminate the need tT~rredesign of the memory portion of a n]ic|-oprocessor systenl each time tile firmware changes. Cell layout boosts speed of low-power 64-K RUM. DENNIS R. WU.SON. Electronics p. 96{30 March 1978). A 64-K MOS read-only memory has been developed that sets a new high for R U M density and performance. T h a n k s to a layout thai shares elements a m o n g many cells and a dynamic peripheral circuit design that reduces power and increases speed, this chip operates typically with access times of 80 nanoseconds and power dissipations of 150 milliwatts. That's the best speed power performance yet offered by any R U M of any size.
Ihan 500 hours.
A charge-sheet model of the MOSFET. ,I. R. Brews. N,did-St. Eh.,ctron. 21,345 (1978). Intuition, device evolution, and even efficient computation require simple M O S F E T (metaloxide semiconductor lield-effect transistor)models. Among these simple models are charge-sheet models which compress the inversion hlyer into a conducting plane of zero thickness. It is the purpose of this paper to test one such chargc sheet model to see whether this approximation is too severc. I his particular model includes diffusion which is expccted to be important m the subthreshokt and saturation regions As a test the charge sheet model is applied to longchannel devices. Long-channel M O S F E T behavior has been thoroughly studied, and is very well explained by the Pao Sah double-lntegral formula for the current. Hence, a clear-cut test is a comparison of the charge sheet model with the Pao Sah model. We lind the charge sheet model has tv, o advantages o,,er lhe Pao Sah inodel.
D.c. and high-frequency characteristics of builtqn channel MOS-FETs. PIErrE E. SCHMIm' and MUKUNt~t, B. DAS. Solid-St. Electron. 21, 495 (1978). This paper analyses the d.c. and small-signal a.c. characteristics of M O S - F E T s with a built-in conducting channel that can either be completely depleted or enhanced in conductivity by carrier accumu-
Nonplanar power field-effect transistor (V-f.e.t.). I. I). MOKAND and C. A. T. SALAMA. Solid St. Electro, l)et:ice~ 2, (2) 52 (March 1978). A high-frequency power junction field-effect transistor with a nonplanar V-shaped channel fabricated by preferential etching of (100) silicon is described. The structure of the transistor is very simple: il
Aluminum SOS Schotiky diodes. S. Y. l i s t . R C 4 Rev. 3g, 533 (December 1977). A l u m i n u m SOS Schottky diodes having excellent characteristics are described. The series resistance is relatively large, however. The barrier height of the Al SOS contact is experimentally found to be 0.77 + 0.02 eV. No degradation in diode characteristics was found when the AI SOS Schottky diodes were bias-temperature tested at 1 0 0 C with I ) . - 0 . 1 5 V or lu 10V for more