Showing papers on "Breakdown voltage published in 1982"

Semiconductors for high‐voltage, vertical channel field‐effect transistors

Abstract: The influence of material parameters upon the characteristics of vertical channel power field effect transistors is examined. It is demonstrated that for devices with the same breakdown voltage and device structure, the on‐resistance is inversely proportional to the third power of the energyband gap and inversely proportional to the mobility. In addition the frequency response of these devices increases in proportion to the mobility and the energyband gap. Calculated device parameters for III–V semiconductor compounds, as well as their alloys, have been compared to those of a silicondevice with the same breakdown voltage. It is found that devicesfabricated from GaAs,InP, and GaP are expected to have a current handling capability which is a factor of 12.7, 5, and 1.85 better than that of the silicondevice with the same breakdown voltage. In addition, the current handling capability of devicesfabricated from the alloy semiconductors GaAlAs, GaAsP, and InGaP are even superior to those of a GaAsdevice with the same breakdown voltage.

Manufacture of semiconductor device

Abstract: PURPOSE:To from the excellent bump electrodes on a number of Zener diodes in a short time for the subject semiconductor decice by a method wherein the bump electrode is formed by applying forward voltage at a P-N junction, and a part of the bump is fused by applying reverse voltage which is lower than breakdown voltage CONSTITUTION:For example, a number of windows are provided on the oxide film 4 formed on an N type Si 1, and after a P type diffusion layer 2 has been formed, an Au electrode 6 and a back face electrode 8 are provided on the the layer 2, and a wafer 100 whereon a number of Zener diodes are provided is formed This wafer and a silver electrode 11 are soaked in a plating solution, a power source 12 is connected, the above is silver-plated by applying forward voltage, which is higher than threshold voltage, to the P-N junction and the bump electrode 7 is formed Then, a power source 16 is switched on, the reverse voltage which is lower than the Zener voltage at the P-N junction is applied, and the abnormal bump 7a formed on the defective junction 3a is fused to the extent with which there will be on difficulty for performance of a characteristic inspection Thus, an excellent bump electrode 3 can be formed in a short time for the Zener diode having low Zener voltage

Physical Model of Electric Aging and Breakdown of Extruded Polymeric Insulated Power Cables

Abstract: This paper postulates a physical model of electric aging and breakdown of polymeric insulated high voltage cables and substantiates this model with results of tests. In accordance with the model, scission of molecular chains and formation of craters at discharging voids are responsible for the electric aging and voltage breakdown of polymeric insulation.

A new method of electric field measurements in corona discharge using Pockels device

Abstract: The investigations of the dc electric field distorted by space charges have been made by means of the optical method using a Pockels device. The Pockels device was rotated to eliminate field disturbances caused by surface charges accumulated on it. The present method has the advantage of directly measuring the electric field in a dc corona discharge. The method was successfully applied to the measurement of the electric‐field distribution in a needle‐to‐plane gap of 10 cm with a positive dc corona. The field distortion was clearly observed in a wide range of applied voltages between 30 and 98% of the breakdown voltage 52 kV. It was found that the electric field inside the corona streamers was 3.5 kV/cm, while 14 kV/cm near the tip of the streamers. Furthermore, the experimental results were theoretically confirmed at the relatively low voltage.

Dielectric recovery of an axially blown SF 6 -Arc after current zero: part I-experimental investigations

Abstract: The results are presented of a model experiment to investigate the dielectric recovery of an axially blown sulphur hexafluoride (SF6) arc after current zero With the aid of Schlieren pictures and interferometry, the temperature decay after current zero is observed up to the point of complete recovery of the gap The dielectric recovery is directly measured by applying voltage pulses across the gap which causes breakdown at different times after current zero Residual charges, which play a role in the early recovery phases, are detected using a specialiy developed technique Variations of the shape of the voltage pulses and the geometry cause characteristic changes of the recovery, which support the interpretation of the experimental data

VIA-4 avalanche-induced breakdown mechanisms in short-channel MOSFETs

Abstract: The presence of oxide/semiconductor interface trapped charge (ITC) and its spatial nonuniformity can adversely affect the operation of MOSFETs. The advanced techniques which are used to fabricate circuits with devices of submicrometer geometries make use of radiation which can alter the number and charge state of these defects and modify the device operating characteristics. The traditional methods of measurement of ITC involve the use of large MOS capacitors to obtain accurate values for ITC. Since the processing history of these structures can differ substantially from the processing of typical MOSFETs, the values of ITC obtained from capacitors are often significantly different from the values measured on MOSFETs. Three direct methods for the measurement of ITC using short-channel MOSFETs have been evaluated: 1) the weak inversion method [l], 2) the use of the slope of the subthreshold current [21 and 3) the charge pump method Dl. The weak inversion method breaks down for short-channel transistors because the on-set of saturation in short-channel transistors is not clearly defined. The use of the slope of the subthreshold current is obscured ' by drain induced subthreshold current components. The charge pump method makes use of current produced by repetitively pulsing the channel of a MOSEET from accumulation to inversion and measuring the resulting current produced in an external circuit. When the pulse inverts the substrate, carriers from the source and drain form the substrate inversion layer. These carriers are trapped in the interface de e ts. During accumulation, it is assumed that all the excess mobile carriers in the inversion layer return to the source and drain and the charge pump current is due to the exchange of charge between the interface traps and the bulk silicon. In short-channel devices, this assumption is met. Only the channel width, length, and measurement frequency are required to calculate the ITC density from the charge pump current. Using detailed two-dimensional calculations of the channel inversion shape in short-channel transistors, we have shown that the channel length required for this measurement can be obtained, in a self aligned process, from the gate length. Using an automated parametric test system, the spatial variation of ITC across wafers was measured on pand nchannel MOSFETs fabricated using a self aligned CMOS bulk process. The mean value of ITC for the p-channel device (6.6 X 10" cmV2) was twice the mean for the n-channel device (3.3 X 10" cm-2). This suggest that boron contamination from the source/drain in the p-channel device may contribute to the difference in ITC.

Insulated gate field effect transistor

Abstract: An insulated gate field effect transistor formed in one surface of a semiconductor substrate (1) has a channel, the surface portion of which has an impurity (9) with a conductivity type opposite to that of the substrate (1), and the deeper portion of which has an impurity (8) of the same conductivity type to the substrate. Moreover, the source and/or the drain (6, 7) of the transistor has an impurity layer of a conductivity type opposite to that of the substrate, with an impurity distribution (13, 14) gently sloped. The use of such impurity distributions overcomes the problems of the short-channel effect and reduction of the source-drain breakdown voltage which are present in standard devices. This enables a shorter channel to be used for a given source-drain breakdown voltage which is of advantage in a LSI having a high density of integration.

Barrier voltage and its effect on stability of ZnO varistor

Abstract: The major voltage drop in ZnO varistors occurs across the grain boundaries, which behave generally as Schottky barriers supporting a barrier voltage Vg. This voltage is proportional to the device voltage. Experimental evidence shows that there is a time‐dependent reduction in the barrier voltage combined with an increase in resistive current iR when the varistor is subjected to a continuous ac voltage stress. The phenomena is reversed when the applied voltage is removed, showing nearly complete recovery. Instabilities of the resistive current and of the barrier voltage are shown to be manifestations of the same phenomenon and are attributed to a metastable component in the Schottky barriers. It is proposed that this metastable component is due to interstitial zinc ions that are capable of migration under thermal and electrical driving forces. When these ions are removed or stabilized by a suitable heat treatment, the instability of the device is reduced. This paper presents experimental data and analysis to support this hypothesis.

Gate-drain avalanche breakdown in GaAs power MESFET's

Abstract: The voltage breakdown behavior of a number of different MESFET structures has been investigated using a two-dimensional numerical model. The site of the avalanche is found to be under the drain edge of the gate in recessed devices under all bias conditions, but moves towards the drain contact in planar structures when the channel is not pinched off. The dependence of the breakdown voltage on a variety of geometrical and physical variables has been studied. In particular the surface is shown to play an important part in determining the breakdown voltage.

Pressure Dependence of DC Breakdown of Contaminated Insulators

Abstract: The effect of pressure on dc breakdown voltage of contaminated porcelain insulators and glass models was investigated in the range of 13 to 100 kPa. The study revealed that flashover voltage decreases nonlinearly with lowering of pressure. Arc characteristics under different pressure conditions were studied and the theoretical basis of low pressure flashover is discussed.

Impulse Breakdown Voltage-Time Curves of SF 6 and SF 6 - N 2 Coaxial-Cylinder Gaps

Abstract: The paper constitutes a systematic theoretical and experimental investigation into impulse breakdown voltage time curves of coaxial-cylinder gaps in SF 6 and 50% SF 6 -50% N 2 mixture. The breakdown time delay probability is treated as a bivariate distribution in statistical and formative time lags. A method is developed to deduce the marginal breakdown voltage probability curve from statistics of time delay. The experimental work was performed on a 2.54/7.0 cm diameter 60 cm long coaxial-cylinder electrodes using SF 6 or SF 6 -N 2 mixture pressures of 0.1-0.3 MPa subjected to 0.5/50 ??s and 1.2/50 ??s impulses of both polarities, covering breakdown voltages up to 550 kV and times to breakdown in the range 0.2-7 ??s. Whenever possible, the theory was checked against direct measurements and, considering the complexity of the problem, agreement is judged satisfactory.

El display device

Abstract: A thin-film EL display device incorporates a MOS active matrix Each of the MOS transistor arrays is additionally provided in parallel with a Zener diode for the purpose of protecting the device from a high voltage This Zener diode has a breakdown voltage characteristic corresponding to a difference between a luminous voltage and a non-luminous voltage of an EL display element and clamps the voltage across the MOS transistor, in the "OFF" state, to a voltage less than or equal to non-recoverable breakdown voltage

Impulse Voltage Field Emission Characteristics and Breakdown Dependency Upon Field Strength in Vacuum Gaps

Abstract: High voltage impulses were used to investigate various possible factors influencing the prebreakdown current and breakdown in vacuum gaps of sphere-to- sphere and rod-to-plane.

Modeling and process implementation of implanted RESURF type devices

Abstract: The relationship between breakdown voltage (B.V.) and drift layer charge (Q D ) for RESURF type lateral PN diodes was investigated both theoretically using a 2D computer program and experimentally. As an added variable, substrate doping variations were modeled to verify their effect on the diode B.V. rating. The importance of tight charge control in the drift layer region was demonstrated (both theoretically and experimentally). It is concluded that implantation is necessary to yield a tight B.V. distribution. Also shown experimentally is the associated degradation in B.V. that results when the N+ and/or P+ regions have reduced radii of curvature.

Power semiconductor switching devices—A comparison based on inductive switching

Abstract: In this paper, a comparison of the switching efficiency of MOSFET's Darlington transistors, field controlled thyristors (FCT's), and gate turn-off thyristors (GTO's) will be made for devices with breakdown voltages between 100 and 1000 V. The comparison is made as a function of switching frequency with a 50-percent duty cycle and for devices of the same area, carrying the same current. Conclusions are presented as to the most appropriate device for different combinations of breakdown voltage and switching frequency requirements.

Electrical Breakdown Characteristics of Soil

Abstract: The pulsed electrical breakdown characteristics of soil between a hemispherical and a planar electrode have been measured in meter-size geometries for three soil types with water contents from 1 to 7% by volume. The threshold electric field for breakdown is a function of the soil type and the water content, varying from about 1 to 2 MV/m locally near the hemispherical electrode. The delay time (tD) between application of the voltage and the occurrence of the breakdown is primarily a function of the applied voltage, which varies approximately as tD-3/8 for these samples. After breakdown, the impedance of the soil decreases with time until it reaches a minimum impedance of 0.2 to 5 ?/m for these meter-size samples, depending on the current that the pulser can drive through the arc. The discharge arc prefers to travel underground rather than on the surface of the soil unless there is some low-impedance object on the soil surface.

Method for determining cell membrane dielectric breakdown

Abstract: A method and apparatus which enables cell membrane dielectric breakdown to be determined. This determination is essential for the rapid inexpensive, reliable, in vitro quantification of lymphocyte tumor-cell cytotoxicity, lymphocyte membrane fluidity and the analysis of abnormal or tumor cells. The apparatus incorporates therein a cell dispenser used in conjunction with a DC electric field exposure tube. Electronic circuitry and its associated components process, acquire and store cell voltage signals as the cells are drawn through the electric field exposure tube. The procedure involves quantifying the breakdown voltage required to electrically collapse the cell membrane. The electrical collapse is termed a dielectric breakdown and is characterized by a reversible drop in the cell's resistivity.

Performance Predictions for Electron-Beam Controlled On/Off Switches

Abstract: An electron beam (e-beam) controlled switch makes use of the low-energy secondary electrons in a diffuse e-beam sustained discharge as the conducting medium which carries the switched current. The conductivity of the gas in the switch is negligible before the e-beam is turned on because the circuit parameters are chosen so that the open circuit voltage which appears across the switch electrodes is well below the static breakdown voltage of the gas in the switch gap. The e-beam switch can interrupt direct current because the density of the electrons in the switch decays by recombination and attachment when the e-beam is turned off and the switch conductivity decreases. In typical circuits, this decay in conductivity causes the switch voltage to rise and the switch current to fall, i.e., the switch "turns off." This paper presents the results of a series of theoretical calculations which were performed in order to: 1) identify the electron transport and other gas properties which optimize the performance of e-beam switches, 2) evaluate the performance of several real gases for use in e-beam switches, and 3) determine the laws which predict the scaling properties of e-beam switches. Results are presented for N2, Ar, a N2:Ar = 1:9 mixture, and CH4. These results show that CH4 provides the best e-beam switch performance. Comparison of experimental results and theoretical predictions for CH4 supports both the theory and the predicted good e-beam switch performance for CH4.

High current post‐hydrogenated chemical vapor deposited amorphous silicon p‐i‐n diodes

Abstract: Amorphous silicon p‐i‐n diodes have been fabricated for the first time by chemical vapor deposition and post‐hydrogenation in a hydrogen plasma. By analyzing the current‐voltage characteristics we obtain current densities up to 50 A/cm2 and rectification ratios better than 107 for 3‐V applied bias. A characteristic reversible breakdown voltage is observed up to voltages of ∼20 V. These results are compared with those obtained on amorphous silicon p‐i‐n diodes prepared by glow discharge decomposition of SiH4.

High-voltage DMOS and PMOS in analog IC's

Abstract: A lateral 300V DMOS device is described which can be integrated in a standard bipolar IC process. The device, applicable as a high voltage source follower for analog circuits, is based upon the "double-acting resurf" principle; a modification with an interrupted p- top layer or with a stepped field plate is used. The p- layer improves the interconnection-induced breakdown and can be used in the extended drain of a 280 V PMOST.

Impulse Breakdown Behavior of Negative Rod-Plane Gaps in SF6-N2, SF6-Air and SF6-C02 Mixtures

Abstract: Breakdown behavior of a 50 mm negative rod-plane gap is investigated for N2, air, CO2 and their binary mixtures with SF6 for pressures of up to 0.5 MPa using rod of 0.794 mm radius and impulse voltages of 2/50 ?sec. It is shown that at high gas pressures, mixtures containing low SF6 content can have breakdown voltages lower than the corresponding values in pure gases. Furthermore, the results indicate that SF6-CO2 mixtures perform somewhat better than SF6-N2 and SF6-air mixtures and can have breakdown voltages slightly higher than those for pure SF6. On the contrary, SF6-air and SF6-N2 mixtures have breakdown voltage levels which are always below their respective values for SF6. Furthermore, it is shown that when gas pressure is equal or higher than 0.1 MPa, leader-type corona exists in almost all of these mixtures. Also when the gas pressure and SF6 content of the mixture are high, leader discharge extends into the gap in a stepped manner. Detailed results of these investigations are described and discussed in this paper.

The Effect of Morphology on the Impulse Voltage Breakdown in XLPE Cable Insulation

Abstract: This paper describes fundamental studies into the effects of (1) the thermal properties, and (2) the morphology of cross-linked polyethylene on its impulse voltage breakdown stress, as determined by the use of miniature cables. Nine grades of high pressure polyethylene, characterized by molecular structure, are used in the studies. The degree of crystallinity of XLPE is found to be closely related to impulse voltage breakdown stress, which increases when crystallinity is increased. Therefore, the fact that impulse voltage breakdown stress decreases with temperature can be associated with a decrease in crystallinity. Likewise the thickness of the amorphous zone is found to increase with temperature, although the crystal thickness has changed onlyslightly. From this point of view, the amorphous zone appears to play an important role in the occurrence of impulse breakdown in that the breakdown seems to originate from the amorphous zone.

Partial Discharge Testing under Direct Voltage Conditions

Abstract: DC partial discharge (PD) (corona) testing is performed using a multichannel analyzer for pulse storing, and data is collected during increase of voltage and at quiescent voltage levels. Thus high voltage ceramic disk capacitors were evaluated by obtaining PD data interspersed during an accelarated life test. Increased PD activity was found early in samples that later failed catastrophically. By this technique, trends of insulation behavior are revealed sensitively and nondestructively in high voltage dc components.

Zener diode with protective PN junction portions

Abstract: A first rectifying contact portion of a semiconductor device such as a Zener diode has a small area in order to attain a hard breakdown characteristic and a low noise characteristic. When a predetermined current which is not greater than the maximum allowable instantaneous value of non-D.C. currents flows through the first rectifying contact portion, a second rectifying contact portion which has a large area starts breakdown due to a voltage drop across a resistance component connected in series with the first rectifying contact portion and a breakdown voltage of the first rectifying contact portion. Owing to the fact that current is dispersed to the first rectifying contact portion and the second rectifying contact portion, a semiconductor device such as a Zener diode exhibiting a high endurance characteristic against surge voltages can be provided.

Filamentary breakdown of gases in the presence of dielectric surfaces

Abstract: The effect of dielectric surfaces on the breakdown voltage of gas spark gaps were investigated both theoretically and experimentally Experiments have been carried out using N2 and other gases at pressures ranging from one to five atmospheres Several different dielectric materials were used as substrates, having plain and cylindrical surface geometries The observed results were interpreted by a physical model which was developed for this purpose In the model, the major physical processes, ie, electron production and electron loss due to diffusion, were treated in the presence of the dielectric surface In addition, electron loss due to electron traps on the dielectric surface has also been taken into consideration The model yields an analytical expression for the breakdown voltage of a given gas spark gap For the cases studied, the model predictions fit the observed results reasonably well

Three-dimensional simulation of VLSI MOSFET's: The three-dimensional simulation program WATMOS

Abstract: With the advent of 2- and 1-µm VLSI silicon technologies, evaluation of the threshold, density, power, speed, circuit margins, punchthrough, and breakdown requires three-dimensional simulations. This paper describes a computer simulation program based on a three-dimensional model for small-geometry MOSFET's. The effect of Si-SiO 2 interface charge, ion implantation in the channel, p+isolation field ion implant (channel isolations), and shape of the field oxide are all included in the model. Our three-dimensional simulations revealed a new insight into VLSI MOSFET devices. Some of these results include "wedge-like" effective channel width, the effective channel width under certain bias conditions decreases to 63 percent of its nominal value. Saddle point related to punchthrough current locus; the punchthrough current per unit width as a function of the channel width was found for the first time to decrease rapidly as the channel width was reduced below 5 µm. A decrease of punchthrough current by three orders of magnitude was observed as the channel width was reduced from 2 to 1 µm. The breakdown voltage of small-geometry devices increases as the channel width decreases. Subthreshold current, potential and electric field distributions, and threshold voltage are significantly different from those calculated using two-dimensional analysis. This simulation program can be used for design of small-geometry MOSFET's and estimation of small-geometry effects in submicrometer size devices. It can be used to evaluate new VLSI and VHSIC technologies. Finally it can be used to test simple models for use with CAD programs.

Surface Topography of Printed Wiring Boards and Its Effect on Flashover

Abstract: Breakdown voltage values between conductor paths on epoxy-glass printed wiring boards (PWB's) are shown to lie on the Dakin curve relating the breakdown voltage with the dielectric constant and conductor separation on the insulator. However, the insulator surface roughness is shown to affect the breakdown voltage, the smoother the surface the lower the breakdown voltage. With a roughness (peak to valley) on the order of 10 µm or greater on epoxy-glass, the breakdown voltage approaches that of an equivalent air gap. Multiple filamentary discharges were observed per flash over similar to normal air breakdown. Erosion products from flashover include small copper spheres, from the damaged printed wiring lines, scattered around the damaged area on the PWB where, in many cases, the glass fiber supports were exposed. These effects can accelerate the degradation of the PWB insulator substrate.

Material Studies in a High Energy Spark Gap

Abstract: The chemical interactions and physical processes occurring in a high energy spark gap with different combinations of gases, electrodes, and insulators were studied. The electrodes studied were graphite and a tungsten-copper composite; the insulators were Lexan and Blue Nylon; and the gases were N2 and SF6. The gas composition was monitored with a mass spectrometer. Spectroscopic techniques were used to observe the arc channel. The electrode surfaces were studied with several surface analysis techniques, including scanning electron microscopy, electron spectroscopy for chemical analysis, Auger electron spectroscopy, and X-ray fluorescence. The breakdown voltage distribution was examined for different material combinations. The plasma chemistry processes involving the gas, electrode, and insulator materials were found to affect the voltage self-breakdown distribution. The detailed surface analysis gave information about the nature of the chemical processes. The presence of Blue Nylon seemed to have a more adverse effect than Lexan and graphite seemed to have a narrower voltage distribution than the tungsten-copper composite.