Electrostatic Discharge Energy Research Articles

Characterization of ESD-induced electromigration on CMOS metallization in on-chip ESD protection circuit

Electrostatic discharge (ESD) and electromigration are critical issues that significantly impact the reliability of ICs. While both of these phenomena have been studied independently, the combination of the two, ESD-induced electromigration, has received less attention, potentially compromising IC reliability. This work analyzes various types of metal with different lengths, widths, and angles commonly used in ESD protection circuits in the CMOS process. The objective is to observe their behavior under continuous ESD zapping. The ESD-induced electromigration of metallization in the CMOS process has been analyzed, and metal sensitivity to system-level ESD events has also been identified. It is also analyzed from the perspective of energy that the ESD energy that metal can withstand will decrease as the ESD voltage increases, which will be even more detrimental to the ESD reliability of ICs. The findings from this study aim to provide valuable insights for designing metal lines in ICs to enhance ESD protection.

A False Trigger-Strengthened and Area-Saving Power-Rail Clamp Circuit with High ESD Performance.

A power clamp circuit, which has good immunity to false trigger under fast power-on conditions with a 20 ns rising edge, is proposed in this paper. The proposed circuit has a separate detection component and an on-time control component which enable it to distinguish between electrostatic discharge (ESD) events and fast power-on events. As opposed to other on-time control techniques, instead of large resistors or capacitors, which can cause a large occupation of the layout area, we use a capacitive voltage-biased p-channel MOSFET in the on-time control part of the proposed circuit. The capacitive voltage-biased p-channel MOSFET is in the saturation region after the ESD event is detected, which can serve as a large equivalent resistance (~106 Ω) in the structure. The proposed power clamp circuit offers several advantages compared to the traditional circuit, such as having at least 70% area savings in the trigger circuit area (30% area savings in the whole circuit area), supporting a power supply ramp time as fast as 20 ns, dissipating the ESD energy more cleanly with little residual charge, and recovering faster from false triggers. The rail clamp circuit also offers robust performance in an industry-standard PVT (process, voltage, and temperature) space and has been verified by the simulation results. Showing good performance of human body model (HBM) endurance and high immunity to false trigger, the proposed power clamp circuit has great potential for application in ESD protection.

Removal of powders from cavities in contaminated surfaces by shock and plasma generated by an adjacent electro-static discharge

An electrostatic discharge (ESD) produced between pin electrodes above a cavity filled with powder is explored as means of contactless removal of particles from contaminated surfaces. The ESD is produced by discharging a capacitor through an air gap. Glass beads of different sizes serve as model powders filling cavities of different depths. Masses of both loaded and ejected powders are measured. The motion of the ejected particles is studied using high-speed video. Most of the ejected particles move vertically up with the initial velocities varied from ca. 4 to 11 m/s. Changing the mechanical properties of the substrate holding the powder does not significantly affect the velocities of the ejected particles. For powders removed from cavities as a result of interaction with the shock and plasma produced by ESD, the number of particle layers ejected is determined by the particle size and the ESD energy, but is not significantly affected by the cavity depth. A single ESD pulse can be effective in the complete removal of powder particles from relatively shallow, 0.2-mm deep cavity. Estimates suggest that the particles are primarily ejected due to the lift forces produced by local velocity gradients of the gas above the loaded powder layer.

Measurement of the effect of parasitic capacitance in minimum ignition energy spark generation circuits

To accurately measure electrostatic discharge energy, a resistive-capacitive voltage discharge approach was used to measure the parasitic capacitance in a circuit. As a result, an output-stage parasitic capacitance in the circuit during the discharge process and a non-negligible storage-stage parasitic capacitance during the charging process were identified. By comparing the data obtained from the resistive-capacitive discharge voltage model and spark current RCL circuit model, the maximum relative deviation from the total circuit capacitance was 5.4% for both approaches. A model based on graded-stage parasitic capacitance was established to analyze the effect of this capacitance on discharge energy. The energy stored in the charging process increased because of the storage-stage parasitic capacitance, and the discharge energy decreased because of the output-stage parasitic capacitance. The energy calculated by the graded parasitic capacitance model was larger than that calculated by the single-stage parasitic capacitance model, with a maximum relative deviation of 36.7% under the test conditions. The smaller the charging capacitor, the more evident the effect of the parasitic capacitance on the discharge energy.

Bio-inspired synthesis of RDX@polydopamine@TiO2 double layer core–shell energetic composites with reduced impact and electrostatic discharge sensitivities

To reduce the impact and electrostatic discharge sensitivities of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), the polydopamine (PDA) and amorphous TiO2 were used as shell materials to construct a series of RDX@PDA@TiO2 double layer core–shell energetic composites with an RDX as the inner core and amorphous TiO2 as the exterior shell; and the PDA was employed as bio-adhesive agent coated on the surface of RDX to enhance the interfacial adhesion between RDX and amorphous TiO2. Then, by the characteristics of scanning electron microscopy (SEM), flourier-transform infrared (FT-IR) spectra, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the double layer core–shell structure of RDX@PDA@TiO2 composites was indicated; and the reaction mechanism of the depositions of amorphous TiO2 shell was proposed. Furthermore, we explored the influence of different content, morphologies of amorphous TiO2 shell and thickness of PDA on the desensitization effect of RDX@PDA@TiO2 composites. Compared with pure RDX, the RDX@PDA@TiO2-1#, -2#, -3#, -4#, -5# samples exhibited significant enhancement of 4.0 J (26.7%), 15.3 J (102.0%), 28.2 J (188.0%), 30.0 J (200.0%), 21.8 J (145.3%) of impact energy, and 0.7 (50.0%), 1.0 J (71.4%), 2.2 J (157.1%), 7.2 J (514.3%), 5.9 J (421.4%) of electrostatic discharge energy, respectively. And the prepared RDX@PDA@TiO2 composites with thicker and lager particle size of amorphous TiO2 shell leaded to better desensitization effect. This work potentially provided an alternative method for improving vulnerability and transportation safety of RDX.

Ignition of zirconium powders placed near an electrostatic discharge

Abstract Electrostatic discharge (ESD) or spark produced by breakdown of a gap while discharging a capacitor is a common ignition stimulus for powders of reactive and energetic materials. It is a safety hazard, but is also used to initiate pyrotechnic formulations and as a characterization method of reactivity of energetic materials. In previous experimental studies, the powder served as one of the ESD electrodes. Ignition was found to be caused by Joule heating, with the main heat release by current passing through points of contact between particles. However, ignition may occur when the ESD does not pass directly through the powder. ESD generates a shock wave, which can lift the powder from a substrate even if the substrate is not an electrode. ESD also generates a plasma kernel heated to ca. 10,000 K, which exists for hundreds of µs, often much longer than the ESD current. Here, the effect of the ESD-induced shock and plasma on a reactive powder was studied experimentally for the first time. A thin layer of Zr powder was placed on a substrate located under a spark gap between two pin electrodes. Photo-sensors and high-speed video were used to document ignition and combustion events. The ESD energy and distance from the spark gap and powder were varied. At close distances, particles ignited consistently. Distance limits were determined, beyond which ignition was no longer observed. Higher ESD energies as well as longer ESD pulses led to ignition at greater distances. Ignition involved two distinct processes. First, submicron particles were lifted from the substrate on a time scale of single microseconds, interacted directly with the plasma kernel, and combusted. Optical emissions from this combustion lasted 100 – 600 µs, as expected for the burn time of submicron Zr particles in air. The second ignition event occurred several milliseconds later. It involved a flame propagating through Zr powder aerosol or combustion of individual lifted particles. This event was caused by coarser Zr particles radiatively heated during ESD. Importantly, the powder was aerosolized by convective flows caused by the rising plasma kernel making it possible for the self-heating of particles oxidizing in air to eventually lead to their ignition and combustion. Observed times for these delayed ignition and combustion events were in the order of tens of milliseconds.

Displacement of powders from surface by shock and plasma generated by electrostatic discharge

Fine particulates were removed from a flat surface and cavities by shock/plasma produced by electro-static discharge (ESD). The ESD in air formed by discharging a capacitor between two 1-mm separated pin electrodes. Both irregularly shaped glass and spherical magnesium served as contaminant particulates. The ESD energy and pressure produced by the shock were characterized. Both powders were effectively displaced by the ESD-generated shock and plasma. Displaced particles were de-agglomerated. While glass melted, flammable magnesium powder did not ignite. ESD-generated plasma and shock offer an attractive, inexpensive, and safe alternative to laser shock cleaning methods for removal particulate contaminants from surfaces.

Facile formation of nitrocellulose-coated Al/Bi2O3 nanothermites with excellent energy output and improved electrostatic discharge safety

Nanothermites are attracting much attention for energetic applications. However, they suffer from high electrostatic discharge (ESD) sensitivity which makes their handling hazardous. Developing safe yet powerful nanothermites is still a challenge. In this work, nitrocellulose (NC) was adhered to the surface of Al and Bi2O3 nanoparticles by a facile electrospray method aiming to improve the ESD safety and energy output of Al/Bi2O3. The morphological and compositional characterization of Al/Bi2O3@NC confirms the NC-coated structure. Benefiting from the structure, the ESD safety of coated Al/Bi2O3 is improved, for instance, the Al/Bi2O3@NC containing 10wt% of NC has a ESD ignition threshold to be 81mJ instead of 1mJ for the Al/Bi2O3 without NC. On the other hand, tunable energy output is obtained by the addition of NC coating. Specifically, Al/Bi2O3@NC (3wt%) exhibits remarkably enhancements in pressurization, combustion reaction and heat release, which even outperforms the most widely used primary explosive lead styphnate (LTNR). The enhancements are attributed to the fact that NC serves as a gas-generating agent to prevent the nanoparticles from sintering to larger particles and enables sufficient combustion. These results suggest that the electrospray formation of NC-coated nanothermites is a facile strategy for obtaining novel nanothermites.

Rail Clamp with Dynamic Time-Constant Adjustment

A dual time-constant rail clamp for protecting CMOS circuits during electrostatic discharge (ESD) events is described. In the new circuit, a relatively small time constant is dynamically adjusted after the clamp is triggered during the ESD event, to keep the clamp conducting and dissipate the full ESD energy. The design is area-efficient, can support applications with power-on times as fast as 200 ns, is immune to lock-on during normal powered-on operation, and corrects very quickly when accidentally triggered. The circuit is able to maintain robust performance over industry standard process, voltage, and temperature (PVT) conditions. Experimental results from fabricated silicon die and performance comparisons with the traditional circuit are presented.

Ignition of Fully Dense Nanocomposite Thermite Powders by an Electric Spark

Electrostatic discharge ignition of nanocomposite thermites prepared by Arrested Reactive Milling was investigated. The powders 2Al–3CuO and were placed in a sample holder and subjected to an electrostatic discharge from a discharging capacitor. Their optical emission was monitored. Two ignition modes were detected: immediate ignition of individual particles and delayed ignition of a cloud of aerosolized powder. Experiments addressed the effects of material composition and morphology, aging, energy input, layer thickness, and environment on the ignition mode and ignition delays. Prepared thermites were blended with pure metal powders to study ignition of such blends. Individual particle ignition was observed for samples prepared as monolayers in air and argon and for any samples in vacuum. For thicker samples in air and in argon, a delayed powder ignition mode was observed. The delays varied from to several milliseconds. Powders of 2Al–3CuO had shorter ignition delays compared with . For both materials, delays decreased for the powders prepared using longer milling times. For 2Al–3CuO, aged powders ignited after longer delays compared with the freshly prepared powders; however, shorter delays were observed for the aged . Electrostatic discharge energy and layer thickness (except for a monolayer) did not affect the ignition delay. Blending nanocomposite thermites with Al and Ti powders reduced their electrostatic discharge ignition sensitivity and caused longer ignition delays.

A low leakage power-rail ESD detection circuit with a modified RC network for a 90-nm CMOS process

An electrostatic discharge (ESD) detection circuit with a modified RC network for a 90-nm process clamp circuit is proposed. The leakage current is reduced to 4.6 nA at 25 °C. Under the ESD event, it injects a 38.7 mA trigger current into the P-substrate to trigger SCR, and SCR can be turned on the discharge of the ESD energy. The capacitor area used is only 4.2 μm2. The simulation result shows that the proposed circuit can save power consumption and layout area when achieving the same trigger efficiency, compared with the previous circuits.

Some electrostatic factors may cause gas explosion in coal mines

The human body capacitances vary greatly when miners leave a narrow tunnel. The human body electrostatic discharge energy is increased at the outlet of narrow tunnels. Thereby the possibility of detonating gas is greatly increased. Human body electrostatic half-life changes according to the dress of miner. Intense movements of human body will increase the static electricity produced in unit time. This can also increase the human body static electricity and cause gas explosion.

3성분계 인화성 혼합가스의 최소점화에너지 측정에 관한 연구

When flammable gases are mixed with air or oxygen in the explosion concentration range and are ignited by sufficiently large electrostatic discharge energy, they may explode causing severe disaster in workplace. The minimum ignition energy(MIE) of single gas-air mixtures has been already investigated by many research, but the MIE of mixtures of more than ternary gas mixture is not examined yet. The purpose of this study is to investigate the MIE of a ternary gas(methane, ethylene, hydrogen, propane) mixtures experimentally. The results of our experiment show that the ignition of a methane-ethylene-air, methane-hydrogen-air, methane-propane-air, ethylene-hydrogen-air, ethylene-propane-air and hydrogen-propane-air mixture due to electrostatic discharge energy primarily depends on that the mixture: the MIE decreases gradually with the increase of having the lower MIE than other mixture ratio in the normal atmospheric pressure.

Model of heating and ignition of conductive polydisperse powder in electrostatic discharge

Heating of a conductive polydisperse powder by electrostatic discharge (ESD) is modelled numerically. Powder packing is described using a discrete element model; powder resistance is defined by geometry of particle contacts and properties of plasma produced by electrical breakdown between neighbour particles. A set of parametric calculations in combination with experimental data is used to determine necessary adjustable model parameters. The model predicts the temperature for each powder particle resulting from its heating by the ESD current. Location and packing of individual particles within the powder affects greatly their achieved temperatures and thus the likelihood of ignition. Consistently with experiments, a trend showing that smaller particles are generally heated to higher temperatures at a given ESD energy is detected for coarser powders; this trend becomes less clear for finer powders with particle sizes less than the breakdown distance given by the Paschen curve in air. Comparison of the experimental data and calculations suggests that the transition from single particle to cloud combustion occurs when the distance between the particles ignited by ESD becomes close to the flame size for the individual burning particle. This distance, inversely proportional to the number of ignited particles, is primarily determined by the ESD energy.

Characterization of Contact Discharge Between Small-Capacitance Devices

The giant-magnetoresistive head suffers magnetic damage from electrostatic discharge (ESD) current on the order of 10 mA and thermal damage from ESD energy on the order of 0.5 nJ. The discharge between 2-pF capacitors at 10 V gave a peak current of 34 mA, and the discharge between 100-pF capacitors at 100 V reached 1.5 A. The peak current arose on the order of picofarads and was approximately maximized at the same value of both capacitors. Theoretical energy loss was estimated by the difference between the potential energies prior to and following the discharges. The energy loss was 0.05 nJ for 2-pF capacitors at 10 V and increased in excess of 0.5 nJ for greater than 20-pF capacitors. Therefore, the discharge between picofarad capacitances tends to cause the magnetic damage, and increasing the capacitance causes the thermal damage. Comparison of the potential energy loss and the current energy derived that the contact resistance varied from more than 200 to few ohms as the voltage and the energy loss increased.

Nonlinear capacitors for ESD protection

In order to protect electronic products from Electrostatic Discharge (ESD) damage, multi-layer ceramic capacitors (MLCC) are often used to bypass the transient ESD energy. Most dielectric materials used in MLCC are nonlinear, since the dielectric constant decreases with increasing voltage, reducing the capacitance value, thus degrading the ESD protection effect. Using a large initial capacitance value will ensure sufficient ESD protection; however, the shunt capacitors also limit the signal bandwidth of the ESD-protected data channel, thus setting a maximal capacitance value at data voltage levels. This paper investigates the nonlinearity of capacitors and suggests improved tradeoff between ESD protection and data bandwidth by using the Antiferroelectric (AFE) capacitors as ESD protection. The dielectric constant of AFE material increases with increasing voltage. The voltage dependence of X7R and AFE capacitors are measured using static and nanosecond transient measurements. The ESD protection effectiveness with different material capacitors are compared by simulation. Due to very limited availability of suitable AFE material samples only hand-made capacitors have tested without investigating the long term stability of the material.

Peak current failure levels in ESD sensitive semiconductor devices and their application in evaluation of materials used in ESD protection. Part 1: Theoretical analysis

This paper shows that theoretical analysis of the thermal model of damage to electrostatic discharge (ESD) energy susceptible devices combined with data from Human Body Model test on devices can be used to estimate an ESD pulse current threshold for damage to ESD energy susceptible semiconductor devices over a wide range of ESD duration and waveforms. The technique is intended for laboratory evaluation of ESD threats from equipment, materials and other ESD sources in the electronics assembly factory environment. In Part 2 of this paper the predicted ESD current damage threshold is experimentally demonstrated to give a useful boundary to a ‘safe’ area of ESD current and duration.

Electrostatic discharge attenuation test for the characterization of ESD protective materials

New experimental method has been developed to evaluate materials, tools, equipment and packaging used in the electronics production environment under Charged Device Model (CDM) type of electrostatic discharge (ESD) transients. The method is intended to characterize the ability of the material or object to attenuate ESD energy and peak discharge current when a charged device is discharged into the material under test. The test is supplementary for the standard quasi-static measurements of ESD control programs in the cases where standard measurements do not give sufficient information due to voltage non-linearity, complexity or shape of the material or object under test.

Analysis of a dust explosion caused by several design errors

AbstractA chemical reaction process began by feeding a combustible fine powder into a reactor through a charging hopper. The reactor and the charging hopper were fitted with a nitrogen inerting system to prevent dust explosions. Surprisingly, a dust explosion occurred when feeding the powder into the reactor from a flexible intermediate bulk container (FIBC).On‐site investigations found that the design of the inerting system allowed a sufficient amount of air to enter the charging hopper. There were no mechanical, electrical, and thermal sources of ignition inside the closed reactor–charging hopper system before the explosion. Electrostatic discharges appeared to be the ignition source; however, the ignition source could not be identified without further analysis by conducting tests. Therefore, various dust explosion and electrostatic tests were conducted to determine (1) the minimum amount of electrostatic discharge energy required to ignite the dust cloud and (2) the likelihood of various types of electrostatic discharges to ignite the dust cloud under the existing design and process conditions. The test results showed that the powder suspended in air at the optimal dust concentration requires <3 mJ of spark energy to ignite. A glass‐lined pipe at the bottom of the charging hopper was found to be the most likely ignition source. Laboratory tests demonstrated that the ignition was the result of a propagating brush discharge from the glass‐lined pipe. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2006

Propagating brush discharge initiation of dust layers – A new test method

In many powder handling processes, powder can be deposited onto a metal or conductive surface layers. If the powders are very good insulators, the deposited layer can build up electrostatic charges to the level of local electrostatic breakdown creating a propagating brush discharge. An explosion hazard can exist if the powder fines cling to the insulating layer in process. The occurrence of a discharge on the insulating layer, either by internal electrostatic breakdown or by moving a grounded object toward the insulating layer, can loft the dust into the air. This discharge may also have sufficient energy to ignite the dust cloud causing catastrophic explosion results. A new test method has been developed to simulate this occurrence. Its goal is to determine the electrostatic discharge energy in the propagating discharge required to ignite the lofted dust. Propagating brush discharge having energies less then 30 millijoules have ignited dust deposits on insulating surfaces backed up by grounded conductive material. A method description and some test results are presented in this paper.