Study On Influence And Mechanism Of Displacement Defect On Ionization Damage Of Bipolar Junction Transistor

Bipolar junction transistor is a kind of electronic components commonly used in aerospace vehicles.It is an important part of microelectronic system.It has many advantages,such as good current driving ability,low noise,good linearity and excellent matching characteristics.In order to study the influence and mechanism of displacement defects on the ionization damage of bipolar junction transistors,the sequential irradiation experiments of protons,C ions,O ions,F ions,Si ions and ⁶⁰Co-γrays with different energies have been carried out for 3DG110C（NPN）and 3CG110C（PNP）bipolar junction transistors in this paper.The displacement damage effect and displacement defect characteristics of bipolar transistors are studied by means of electrical performance analysis,deep level transient spectrum analysis and simulation,and the influence law and micro mechanism of ion irradiation induced displacement defect on ionization damage of bipolar transistors are explored.The results show that the penetration depth of proton irradiation near the Si/SiO₂interface has a great influence on the electrical performance of bipolar junction transistors,and the degradation of current gain occurs only when the penetration reaches the interface region.The number of vacancies produced by ion irradiation is positively correlated with the decrease of current gain of bipolar transistor.For the same kind of high energy heavy ions with different energies,the smaller the energy is,the more vacancy defects are produced and the greater the decrease of current gain is;With the same energy,the higher the atomic number,the more vacancy defects and the larger the current gain decrease.PNP transistors are more sensitive to high energy heavy ion irradiation,and the degradation of current gain is more serious.High energy heavy ion irradiation has little effect on the recombination position of the carriers,and the carriers recombine in the depletion region and the neutral base region of the emitter junction at the same time.70 keV proton irradiation will aggravate the degradation of current gain in bipolar junction transistors irradiated by ⁶⁰Co-γrays;However,both high energy heavy ion and low energy heavy ion irradiation can reduce the current gain degradation of bipolar junction transistors in the subsequent ⁶⁰Co-γradiation.The smaller the energy of high energy heavy ion is,the more obvious the inhibition of ionization damage is;The higher the energy of low energy heavy ion is,the more obvious the inhibition of ionization damage is.The suppression effect of PNP transistor is obviously stronger than that of NPN transistor.The reason why the displacement defects inhibit the ionization damage in ⁶⁰Co-γradiation is that the displacement defects in the oxide layer intercept the holes and the displacement defects in the silicon body anneal.Heavy ion irradiation can produce a large number of displacement defects in the oxide layer,which hinder the hole moving to the interface and inhibit the formation of oxide charges,resulting in the decrease of bulk recombination current and the degradation of current gain.Low energy heavy ions produce the most displacement defects in the oxide layer,and the inhibition effect is the most obvious.The displacement defects in silicon are annealed due to ⁶⁰Co-γirradiation,which also results in the decrease of bulk recombination current and the degradation of current gain.A large number of displacement defects are produced in the silicon body by the low energy heavy ions just penetrating the interface,and the annealing effect is the most obvious.There are few displacement defects and no bulk defects in the oxide layer irradiated by 70 ke V proton,which has little effect on bulk recombination current.However,irradiation increases the concentration of H ion in the oxide layer,which aggravates the formation of oxide charge and interface state,and thus aggravates the degradation of current gain.