Research On The Electromagnetic Damage Effects And Mechanisms Of Semiconductor Devices

The electromagnetic environment of electronic systems is deterioratingincreasingly due to the rapid developments of new concept electronic warfare weaponslike electromagnetic pulse bombs and high-power microwave weapons as well as theextensive applications of radars and wireless communication systems. On the otherhand, semiconductor devices and integrated circuits are characterized by smaller featuresizes, lower power dissipation and higher operating frequency, which increases thesusceptibility and vulnerability of electronic systems to electromagnetic energies.Therefore, it becomes more and more important to study the interference and damageeffects of electronic systems induced by electromagnetic pulses (EMPs) so as toimprove the immunity of electronic systems to EMPs. EMPs can be coupled intoelectronic systems through antennas, cables, apertures and so on, thus resulting in thedegeneration or destruction of semiconductor devices. Hence, the research on damagemechanisms of semiconductor devices caused by EMPs is the basis of research onEMP-induced effects of electronic systems.In this dissertation the damage effects and mechanisms of several typicalsemiconductor devices induced by EMPs are studied by numerical simulations andexperiments with the following research results:1. A two-dimensional (2D) model of a typical high-frequency small-signal diodewith a p-n-n+structure is established for numerical simulations with self-heating effectsand avalanche generation in consideration. Based on the model, transient electrothermalsimulations are performed to simulate the damage process of diodes induced by EMPs,the variations of the distributions of electric field, current density and temperature insidethe diode with time are analyzed in detail, the factors affecting the burnout of diodes arediscussed, and the damage thresholds are calculated. The results show that the burnoutof diodes is caused by thermal mode second breakdown. The occurrence of thermalmode second breakdown is due to the negative temperature dependence of avalanchegeneration rate and the positive temperature dependence of thermal generation rate.When the diode goes into second breakdown, dynamic negative resistance leads to localcurrent concentration, followed by a rapid local temperature rise and finally the burnoutof the diode. The triggering temperature of second breakdown increases with the carrierlifetime and decreases with the delay time. The calculated damage energy thresholdincreases with the pulse width. For the short pulse, the damage energy is approximately constant, and for the long pulse, the damage energy is nearly proportional to the squareroot of pulse width, which is consistent with the thermal models available. Aquantitative comparison with experimental data shows that the simulated energythreshold is more precise than what is predicted by the thermal models.2. A2D model of a typical PIN limiter diode is established for electrothermalsimulations. The transient response of the PIN diode to EMPs is simulated, the physicalmechanisms of the formation and motion of current filaments are analyzed, and thefilament moving mode and its impact on the damage to the PIN diode are discussed.The results show that the instability induced by the current-controlled negativeresistance of avalanching PIN diodes leads to the formation of avalanche currentfilaments in the I layer of the PIN diode, resulting in a succeeding local temperature rise.The negative temperature dependence of avalanche generation rates drives the filamentto move towards low-temperature regions. The motion of filament homogenizes thetemperature distribution in the I layer, thus preventing the PIN diode burnout due tolocal overheating. When the filament arrives at the edge of the device, the temperatureat the edge rises rapidly, which drives the filament to leave the edge and return or jumpto the low-temperature regions depending on the filament current density andtemperature distribution in the device. When the filament temperature exceeds a criticalvalue, the thermal excitation will replace the impact ionization as the major source ofcarriers, and the positive temperature dependence of thermal generation rates willproduce a thermal-electrical positive feedback inside the filament, which will pin thefilament at the edge of the device, thus shrinking it continuously, making the filamenttemperature rise quickly, and leading to the burnout of the PIN diode. For thesubmicrosecond pulse width, the damage energy decreases as the width decreases, andthe uncertainty of the initial position of filaments will lead to a dispersion in the damageenergy of PIN diodes.3. For a typical high-frequency small-signal bipolar junction transistor (BJT), a2Delectrothermal model is established to study the damage mechanism and damagethreshold of the BJT under the injection of the EMP at the base. The results show thatthe damage mechanism of the BJT is related to the pulse amplitude: for a low pulseamplitude, BJT damage is caused by the local burnout at the edge of the base-emitterjunction due to avalanche breakdown, and for a high pulse amplitude, a secondbreakdown in the base-epitaxy-substrate p-n-n+structure results in the local burnout atthe edge of the base neighbouring the emitter before the burnout of the base-emitter junction due to a high current density. The BJT burnout time decreases with the increaseof pulse amplitude, while the damage energy has a minimum value in itsdecrease-increase-decrease tendency. A comparison with experimental results showsthat the model in the dissertation can simulate accurately the burnout process of BJTunder the impact of EMPs.4. High-power microwave front-door injection experiments are carried out in thetwo-stage low noise amplifiers (LNAs), performance degeneration and malfunction ofthe LNAs are studied and destructive failure analyses of the failed LNAs are made. Theresults show that when the injection signal power exceeds a critical value, the noisefigure increases dramatically, the gain decreases, and the performance of the LNAdegenerates; when the signal power increases further to another critical value, the noisefigure and gain deteriorate severely and the LNA loses its main function. With thedecreasing pulse width, the damage power threshold of the LNA increases. The LNAdegeneration or damage is attributed to the first-stage transistor degeneration or damage.The degeneration of the GaAs HEMT is due to the gate-source/drain schottky junctiondegeneration caused by the decline of the gate metallization due to the interdiffusion ofthe gate metal and GaAs, and the degeneration is manifested as reverse leakage currentincreasing and forward voltage lowering of the gate-source/drain junction. The damagemechanisms of the GaAs HEMT are related to the signal waveforms: after the injectionof continuous waves or microsecond-duration pulses, the gate-source short circuit willoccur due to the reverse breakdown of the gate-source junction, after the injection ofsubmicrosecond-duration pulses, the gate-source/drain short circuit will happen due toreverse breakdown of both the gate-source and gate-drain junctions, and after theinjection of nanosecond-duration pulses, the gate-source junction behaves as a resistordue to the gate metallization burnout.