Breakdown Voltage Measurements Research Articles

Submicron gap capacitor for measurement of breakdown voltage in air

We have developed a new method for measuring the value of breakdown voltage in air for electrode separations from 400nmto45μm. The electrodes used were thin film Au lines evaporated on sapphire. The resulting capacitors had an area of 80×80μm2. We demonstrate the ability to deduce the value of the separation of the plates by the value of the capacitance. The data acquired with this method do not agree with Paschen’s law for electrode separations below 10μm, as expected from previous experiments. Amongst the improvements of our method are the measurement of plate separation and the very small surface roughness (average of 6nm).

Flashover voltage of alumina ceramic contaminated by metal vapor in vacuum interrupters

We investigated the influence of metal vapor contamination of ceramic surfaces on flashover voltage (FOV) in vacuum. First, disk shape alumina (Al/sub 2/O/sub 3/) ceramics with surface resistivity (/spl rho/) of 10/sup 2/-10/sup 15/ /spl Omega/ were produced using deposition phenomena of metal vapor emitted from CuCr contacts. The impulse FOV for the ceramics decreased, as /spl rho/ reduced; FOV, the conditioning effect on FOV, and the scattering of FOV decreased when /spl rho/ was below 10/sup 12/ /spl Omega/. Therefore, the criterion value /spl rho/, which maintains excellent flashover performances of ceramic surface, is 10/sup 12/ /spl Omega/. Second, experimental vacuum interrupters (VIs) were produced to measure breakdown voltage before and after forty short-circuit current switchings with 20-40 kA/sub rms/ and were disassembled to measure the /spl rho/ of their inner ceramic surface. In a VI, which has inside diameters at both ends of the main shield much larger than the contact diameter, /spl rho/ was reduced to 10/sup 4/ /spl Omega/, further decreasing breakdown voltage between terminals.

Stochastic and Relaxation Processes in Argon by Measurements of Dynamic Breakdown Voltages

AbstractStatistically based measurements of breakdown voltages U b and breakdown delay times td and their variations in transient regimes of establishment and relaxation of discharges are a convenient method to study stochastic processes of electrical breakdown of gases, as well as relaxation kinetics in afterglow. In this paper the measurements and statistical analysis of the dynamic breakdown voltages U b for linearly rising (ramp) pulses in argon at 1.33 mbar and the rates of voltage rise k up to 800 V s –1 are presented. It was found that electrical breakdowns by linearly rising (ramp) pulses is an inhomogeneous Poisson process caused by primary and secondary ionization coefficients α , γ and electron yield Y variations on the voltage (time). The experimental breakdown voltage distributions were fitted by theoretical distributions by applying approximate analytical and numerical models. The afterglow kinetics in argon was studied based on the dependence of the initial electron yield on the relaxation time Y 0 (τ ) derived from fitting of distributions. The space charge decay was explained by the surface recombination of nitrogen atoms present as impurities. The afterglow kinetics and the surface recombination coefficients on the gas tube and cathode were determined from a gas‐phase model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Effect of pore interconnection on Cu-diffusion-induced failures in porous spin-on low-k dielectrics

The porosity dependence of electric reliability in the spin-on low-k dielectric with the same matrix but with various porosities was examined using time-dependent dielectric breakdown and capacitance voltage measurements. Abrupt changes in the time to dielectric breakdown and a flatband voltage shift were observed when the porosity of low-k dielectrics was between 20% and 30%. Such a characteristic agrees with the positronium annihilation lifetime spectroscopy data, which indicates that the interconnectivity of the pores abruptly increased in those materials with a porosity between 20% and 30%, and it causes an increase in Cu-diffusion-induced failures.

Breakdown and hot carrier injection in deep trench isolation structures

In this paper, we propose intensive investigations of the electrical characteristics of a deep trench isolation structure for a new 0.35 μm CMOS based smart power technology. In particular, it is demonstrated, both experimentally and theoretically, that its blocking voltage can be strongly affected by the presence of charges in the floating polysilicon filling the trench. These charges are shown to appear as a consequence of hot carrier injection through the liner oxide during avalanche operation. The measured breakdown voltage instabilities are explained by TCAD simulation tools as well as by a simple theoretical model based on the capacitive coupling approach.

Study of transient processes in nitrogen by measurements of dynamic breakdown voltages

In this paper the measurements of the dynamic breakdown voltages U b for linearly rising pulses in nitrogen at low pressure are presented. The measurements were carried out for the rates of voltage rise k up to $300\, {\rm V\,s}^{-1}$ . Dependence of the breakdown voltages, delay times and electron yields on the rate of rise were obtained experimentally and theoretically under different conditions. It was found that the overvoltage $\overline {\Delta U_b}$ and the mean effective electron yield $\overline {YP}$ is proportional to $\sqrt k$ ( Y is a number of generated electrons in the interelectrode space per second and P the breakdown probability), while the statistical time delay $\overline t_s$ is proportional to $1/\sqrt k$ . In the second part, the experimental breakdown voltage distributions were obtained, fitted by theoretical distributions and some breakdown parameters relevant to experimental conditions were determined. Based on the approximate analytical and numerical models, the dependence of the effective secondary electron yield γ on the overvoltage and on the rate of voltage rise were derived from these measurements. It was found that γ varies linearly with the overvoltage for a constant k , and the slope of γ is proportional to $\sqrt k$ .

Time‐to‐breakdown characteristics of magnetic tunnel junctions

To investigate the reliability of the MTJs on the roughness of insulating tunnel barrier, we prepared two MTJs with the different uniformity of barrier thickness. Namely, the one has uniform insulating barrier thickness; the other has non-uniform insulating barrier thickness as compared to different thing. As to depositing amorphous layer CoZrNb under the pinning layer IrMn, we achieved MTJ with uniform barrier thickness. First of all, we performed the breakdown-voltage measurement of two junctions and obtained the result having a similar breakdown-voltage about 1.4 V at two all junctions. And then, the time dependence dielectric breakdown (TDDB) measurements of two junctions are carried out under constant voltage stresses. The Weibull fit of our data shows clearly that time to breakdown (tBD) scales with the thickness uniformity of tunnel barrier. And also, Assuming a linear dependence of log(tBD) on stress voltages, we meet with result about the different lifetime of the two MTJs with uniform barrier thickness or non-uniform barrier thickness. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Amorphous fluorocarbon polymer (a-C:F) films obtained by plasma enhanced chemical vapor deposition from perfluoro-octane (C8F18) vapor. II. Dielectric and insulating properties

Amorphous fluorocarbon polymer films (a-C:F) have been grown by plasma enhanced chemical vapor deposition from a new precursor, namely perfluoro-octane (C8F18) vapor. The dielectric and insulating properties of the films have been assessed by means of capacitance–voltage and current–voltage characteristics, breakdown voltage measurements, scanning electron microscopy, and ellipsometric analyses. In the investigated frequency range, 120 Hz–1 MHz, the films have a low dielectric constant (≈2.4) and a low dielectric loss (⩽3×10−2). The electrical conduction mechanism is ohmic in the weak electric field regime, with a bulk resistivity of 4×1015 Ω cm, and a trap modulated space charge limited conduction in the strong electric field regime. For a film thickness between 1 and 12 μm, the dielectric strength varies with film thickness according to EB∼h−0.53. For a film thickness of 1 μm the film dielectric strength was 2.7 MV/cm while for 12 μm it decreased to 0.9 MV/cm. Measurements of the breakdown voltage in nitrogen gas in the low pressure regime between a-C:F coated cathode and copper anode showed an enhancement of the breakdown voltage by a factor of 2.5 with respect to the case of copper–copper electrodes.

Surface and electrical characteristics of poly(amide imide)–poly(dimethylsiloxane) nanocomposites

AbstractA series of poly(amide imide)–poly(dimethylsiloxane) (PDMS) nanocomposites were fabricated through the reaction of poly(amide imide), epoxysilane (coupling agent), and diethoxydimethylsilane (DEDMS) via a sol–gel process. Nanocomposite films were obtained through the hydrolysis and condensation of DEDMS in poly(amide imide) solutions. The existence of the condensation product of DEDMS in the poly(amide imide) matrix was confirmed with Fourier transform infrared (FTIR). The concentration of PDMS on the surface of the poly(amide imide) matrix was observed through a comparison of FTIR and attenuated total reflection spectra. The contact angle of the poly(amide imide)–PDMS composites increased more than 40° with respect to that of pure poly(amide imide). The alternating‐current (ac) breakdown strength was obtained through the measurement of the ac breakdown voltage at the temperature of liquid nitrogen. As the PDMS concentration in poly(amide imide) increased, the characteristics of the insulation breakdown improved greatly. The best ac breakdown strength was observed in a poly(amide imide)–epoxysilane (30 wt %) nanocomposite with 30 wt % PDMS. The samples at the temperature of liquid nitrogen were brittle, as in a glassy state. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 342–347, 2004

Impact of proton irradiation on the static and dynamic characteristics of high-voltage 4H-SiC JBS switching diodes

The effects of proton irradiation on the static ( dc) and dynamic (switching) performance of high-voltage 4H-SiC Junction Barrier Schottky (JBS) diodes are investigated for the first time. In contrast to that observed on a high-voltage Si p - i - n diode control device, these SiC JBS devices show an increase (degradation) in series resistance (R/sub S/), a decrease (improvement) of reverse leakage current, and increase (improvement) in blocking voltage after high-fluence proton exposure. Measured breakdown voltages of post-irradiated SiC diodes increase on average by about 200 V after irradiation. Dynamic reverse recovery transient measurements show good agreement between the various dc observations regarding differences between high-power SiC and Si diodes, and show that SiC JBS diodes are very effective in minimizing switching losses for high-power applications, even under high levels of radiation exposure.

Decrease of breakdown voltages for micrometer-scale gap electrodes for carbon dioxide near the critical point: Temperature and pressure dependences

We performed measurements of breakdown voltages as a function of environmental pressure with 1-μm-gap tungsten electrodes for high-pressure carbon dioxide up to supercritical conditions at different temperatures (305.65, 308.15, and 313.15 K). Breakdown voltage curves exhibit an inflection at around 3 MPa and a drastic decrease near the critical point. The location of the drastic decrease shifts to the high-pressure range and the sharpness and depth decrease with increased temperature. The breakdown voltage in pressure environments higher than that at the inflection point was analyzed systematically using the Townsend theory and density fluctuations. Moreover, comparison with breakdown voltage measurements by 10-μm-gap electrodes indicates that one factor inducing the inflection and the decrease might be electron attachment to existing clusters in dense carbon dioxide.

Process Optimization and Integration of Trimethylsilane-Deposited α-SiC:H and α-SiCO:H Dielectric Thin Films for Damascene Processing

The semiconductor grade organosilicon gas trimethylsilane (Dow Corning Z3MS) can be used to deposit unique amorphous hydrogenated silicon carbide (α-SiC:H)-based alloy films that exhibit desirable properties such as chemical resistance, low stress, low permittivity, and low leakage. These film characteristics are ideal for applications in Cu-damascene interconnect technology. In this work, the results of a comprehensive study of Z3MS plasma enhanced chemical vapor deposition (PECVD) dielectric films are reported where all depositions were performed in commercial production PECVD equipment. Processing for α-SiC:H films deposited from Z3MS/He mixtures was optimized for deposition rate, uniformity, and permittivity. The processing parameters can be tuned for relative permittivity down to making α-SiC:H an attractive substitute for PECVD silicon oxide or silicon nitride. Using mixtures of Z3MS and precursors, α-SiCO:H films were deposited with very high deposition rates and film permittivity as low as These films have been applied in damascene technology. Physical properties and stability of blanket films were studied. Measurement of relative permittivity, leakage current, and breakdown voltage was performed on metal/dielectric/metal structures. Fourier transform infrared, X-ray photoelectron, and high-energy ion scattering spectrometry were used to determine bonding and film compositions. Integration issues related to deep ultraviolet lithography, dry etch, strip, and metallization are discussed. Optimized film processes were integrated into 0.18 μm Cu damascene interconnect process technology and the electrical results were compared to standard PECVD oxide. The results of these studies indicate that the device performance improvements inferred from the blanket film properties can be realized in fully integrated interconnect structures. © 2003 The Electrochemical Society. All rights reserved.

Electrical system for measurement of breakdown voltage of vacuum and gas-filled tubes using a dynamic method

This article describes an electrical system aimed at measuring and data acquisition of breakdown voltages of vacuum and gas-filled tubes. The measurements were performed using a nitrogen-filled tube at 4 mbar pressure. Based on the measured breakdown voltage data as a function of the applied voltage increase rate, a static breakdown voltage is estimated for the applied voltage gradient ranging from 0.1 to 1 V s−1 and from 1 to 10 V s−1. The histograms of breakdown voltages versus applied voltage increase rates from 0.1 and 0.5 V s−1 are approximated by the probability density functions using a fitting procedure.

SiGe (Ge-dot) heterojunction phototransistors for efficient light detection at 1.3– [formula omitted

The aim of this work is to develop a Si/SiGe HBT-type phototransistor with several Ge dot layers incorporated in the collector, in order to obtain improved light detectivity at 1.3– 1.55 μm . The MBE grown HBT detectors are of n–p–n type and based on a multilayer structure containing 10 Ge-dot layers (8 ML in each layer, separated by 60 nm Si spacer) in the base-collector junction. The transistors were processed for normal incidence or with waveguide geometry where the light is coupled through the edge of the sample. The measured breakdown voltage, BV ceo, was about 6 V . Compared to a p–i–n reference photodiode with the same dot layer structure, photoconductivity measurements show that the responsivity is improved by a factor of 60 for normal incidence at 1.3 μm . When the light is coupled through the edge of the device, the detectivity is even further enhanced. The measured photo-responsivity is more than 100 and 5 mA/W at 1.3 and 1.55 μm , respectively.

0.15 μm gate-length AlGaN/GaN HEMTs with varying gate recess length

The effect of gate-recess length on DC and RF performance of AlGaN/GaN gate-recessed high electron mobility transistors (HEMTs) was studied. 0.15 μm gate-length AlGaN/GaN HEMTs with varying gate-recess length from 0.5 to 1.0 μm were fabricated. DC and microwave performance did not exhibit significant dependence on the gate-recess length. The devices showed a maximum drain current density as high as 1.1 A/mm, a unity gain cutoff frequency of 79 GHz, and a maximum frequency of oscillation of 125 GHz. The measured series source resistances were essentially identical for all devices. Therefore, all the gate-recessed HEMTs exhibited similar DC and RF performance. This conclusion is derived from the fact that the values of ohmic contact resistances dominated over the values of channel resistances. The nature of the breakdown in the HEMTs was also studied. The results of temperature-dependent breakdown voltage measurements suggest that the breakdown mechanism was mainly due to tunneling gate leakage currents via shallow traps.

Influence of bubble size and flow velocity on AC electrical breakdown characteristics of LN 2

To evaluate insulation design of high voltage for high T c superconducting (HTS) power apparatus, the effect of bubble and electrode arrangements on the AC breakdown characteristics of LN 2 were investigated. Supposing that an outbreak of quench, the three electrode models were employed for breakdown voltage measurement in LN 2 with bubbles. Experimental results for various quench conditions revealed that the breakdown voltage of LN 2 with increasing the bubble size, flow velocity and electrode distance. Then, the relationship between the bubble conditions and the AC breakdown characteristics of LN 2 were clarified. Also, bubble movement phenomena were observed with an electrode model which consist of plane to cylindrical needle electrode immersed LN 2 for the simulation of the insulation environment in HTS pancake type coils and others of the quenching state.

Narrow-channel effects and their impact on the static and floating-body characteristics of STI- and LOCOS-isolated SOI MOSFETs

Narrow-width effects are investigated in LOCOS and STI-isolated silicon-on-insulator (SOI) MOSFETs. With width as a parameter, variations in threshold voltage, mobility, subthreshold swing and drain-induced barrier lowering are analyzed in relationship with the other transistor dimensions (i.e. channel length, and film thickness). For both isolation techniques, a strong dependence of the threshold voltage with the channel width as well as the SOI silicon film thickness are observed while narrow and short-channel effects are not found to be correlated. Following this, it is shown through saturation subthreshold swing, latch-up and breakdown voltage measurements, that the floating-body effects (FBEs) are reduced in narrow-channel devices. Specific experiments (current transients, source–body junction current…) and simulations were conducted to reveal the mechanisms responsible for the observed weakening of the FBEs. It is concluded that three main mechanisms coexist: (i) the local thinning of the film under the LOCOS isolation, (ii) a lower carrier lifetime near the channel edges and (iii) an increase of the source/body junction leakage near the edges which speeds up the removal of the carriers from the body.

The effects of high-dose gamma irradiation on high-voltage 4H-SiC Schottky diodes and the SiC-SiO/sub 2/ interface

The effects of radiation on high-voltage 4H-SiC Schottky diodes for use in extreme environment power supplies are investigated for the first time. Diodes were fabricated with a wide range of barrier heights (1.06-1.60 eV) and were evaluated after being exposed to a /sup 60/Co gamma radiation source. DC current-voltage characteristics were measured after several radiation doses, with no observable degradation in the diode forward or reverse characteristics up to a total dose of 4 Mrad(Si). Measured breakdown voltages of post-irradiated diodes increase approximately 200 V compared to the virgin devices and are attributed to increased negative interface charge, as determined by MOS capacitor measurements and correlated with numerical breakdown simulations.

A high-sensitivity polyimide capacitive relative humidity sensor for monitoring anodically bonded hermetic micropackages

This paper presents the design, fabrication and complete characterization of a high-sensitivity polyimide-based humidity sensor for monitoring internal humidity level in anodically bonded hermetic micropackages. This capacitive sensor is 1 mm on a side and utilizes CU1512 polyimide film with a thickness in the range from 300 /spl Aring/ to 1200 /spl Aring/ sandwiched between two metal electrodes to sense moisture. The measured sensitivity for a sensor with a 1200-/spl Aring/-thick film is 0.86 pF/%RH, and for a 300-/spl Aring/-thick sensor is 3.4 pF/%RH. The sensor has been exposed to and survived a one-hour test at 400/spl deg/C, which is the temperature typically used to perform anodic bonding. Measurements show a drift of less than 1% RH at 50% RH and 37/spl deg/C for 48 h, and a hysteresis of <2% RH over a range from 30 to 70% RH for a 1200-/spl Aring/-thick polyimide film sensor. The measured breakdown voltage of the sensor (1200 /spl Aring/ thick) exceeds 20 V and agrees well with other results.

Electric field breakdown at micrometre separations in air and nitrogen at atmospheric pressure

For efficient operation, micromotors and microactuators, such as those employed in microsystems, are required to operate with high electric fields at electrode separations of the order of micrometres. An apparatus was built to accurately measure the breakdown voltage for electrode spacings as low as 0.5 µm. Breakdown voltage measurements in air and nitrogen are presented and discussed for the gap range 0.5 to 15 µm. Energy dispersive analysis of X-rays (EDAX) confirms the transfer of material from cathode to anode and vice versa during the breakdown mechanism. The Paschen law has been confirmed not to be applicable at gap settings of less than 4 µm. The shape of the curve and the breakdown voltage values are found to be the same for different gases and different high pressures up to 4 µm separation. Below this value, an analytical explanation of the breakdown voltage based on quantum tunnelling of electrons is obtained in terms of electrical field enhancement at microprotrusions and the work function of the electrode material.