【作者】 李兴冀；

【导师】 杨德庄；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2010， 博士

【摘要】 本文在分析轨道环境参数、地面模拟试验因素等影响的基础上,应用不同能量质子、电子、Br离子及Co-60 ?射线作为辐照源,研究了国产NPN型晶体管(3DG112D、3DG130D)、PNP晶体管(3CG130D)及TTL集成电路(54LS86)的辐照效应和性能退化规律。在此基础上,揭示了双极型晶体管的电离效应、位移效应及电离和位移协同效应的机制,给出了双极型晶体管电离损伤量化模型,并提出了基于器件敏感区NIEL的位移损伤等效模拟试验方法。研究结果表明,在相同的辐照源种类、粒子能量及通量条件下,不同双极型晶体管与集成电路的电性能参数退化趋势相类似,均随辐照注量的增加而加剧。不同双极型晶体管对辐照损伤的敏感性可通过相同性能参数(如电流增益)进行比较。辐照通量在所选择的范围内对双极型器件的电性能退化影响不大,而高通量1MeV电子辐照会加剧双极型集成电路的某些电性能参数(如54LS86器件的VOH)的退化。通过分析双极型晶体管辐照损伤的性能退化规律及单位注量入射粒子的电离吸收剂量Di和位移吸收剂量Dd,提出了Dd/(Dd+Di)作为判定辐照粒子产生位移损伤能力大小的参数。入射粒子在器件敏感区内产生的Dd/(Dd+Di)越大,造成的位移损伤越严重,器件的电性能退化越易呈现位移损伤的特征。在此基础上,基于敏感区NIEL的位移吸收剂量等效方法,可将多种辐照粒子造成的位移损伤进行归一化。通过70keV和110keV电子及70keV质子辐照试验结果表明,当晶体管受到电离损伤时,其电流增益的倒数随辐照注量的增加而增加且逐渐趋于饱和状态。在相同的辐照注量下,不同种类和能量的入射粒子对双极型晶体管产生不同的电离损伤程度,主要是由于入射粒子的电离损伤能力不同。通过理论计算与性能退化规律分析可知,单位注量入射粒子所导致的电离辐射吸收剂量越大,对双极型晶体管造成的电离损伤程度越小。基于辐照过程中双极型晶体管偏置条件的影响分析可见,偏置条件对电离损伤和位移损伤的影响程度不同。当发射结电压正偏时,耗尽层宽度变窄,受电离效应的影响变弱,导致电离损伤程度较小;反之,反偏会使电离损伤程度加大。偏置条件不会对位移损伤导致的体缺陷造成较大的影响,使位移损伤受偏置的影响较小。但在发射结正偏时,由于电荷的注入,会使基区内的体损伤发生退火效应。从质子和电子综合辐照试验及器件模拟分析两方面,揭示出双极型晶体管呈现电离和位移协同效应的机理。研究结果表明,170keV质子和110keV(或70keV)电子综合辐照时,位移损伤是决定双极型晶体管电性能退化的主导机制,而电离效应会对位移效应起到退火和加剧两种作用。电离效应可在Si体内产生光电流并钝化一部分位移效应导致的体缺陷,造成位移损伤的退火;电离效应在氧化物层内产生的正电荷及Si/SiO2界面处的界面态,会使表面复合电流峰向体内移动,导致对体复合电流的影响增强,加剧位移损伤效应。并且,NPN型和PNP型双极型器件的电离和位移协同效应变化趋势一致。基于空间辐射环境参数计算、地面模拟试验结果及辐照损伤效应分析,提出了用于评价双极型器件在轨性能退化的预测方法。该方法考虑了轨道环境中不同种类和能量带电粒子对电离效应和位移效应的贡献,具有实际应用的价值和可行性。更多还原

【Abstract】 The degradation caused by protons, electrons, Br ions with various energies and Co-60 ??ray radiation are examined for the domestic NPN transistors (3DG112D, 3DG130D), PNP transistors (3CG130D) and TTL ICs (54LS86), based on the analyse of space environment factors and ground-based simulation experiments. The mechanisms of ionization damage, displacement damage and their synersistic function are investigated. The model of ionization damage for the bipolar transistors is given, and the NIEL (Non-Ionizing Energy Loss) method for displacement damage is improved.Experimental results show that with increasing irradiation fluence, the degradation trends of different bipolar transistor and bipolar ICs are similar, under a given condition for different particles, fluxes and energies. The susceptibility of various bipolar transistors to radiation damage can be assessed by using a given parameter of electric properties (e.g., the current gain). The effect of irradiation flux on the degradation in electric properties of bipolar devices is limited, in the chosen flux range. However, the 1MeV electron exposure with high fluxes aggravates the degradation of some electric property parameters (e.g., the VOH for the 54LS86 device).Based on the analyses of degradation in electric properties due to radiation damage for bipolar transistors and the calculation of ionization and displacement doses per unit fluence of incident particles (designated as Di and Dd, respectively), a parameter of Dd/(Dd+Di) is proposed to evaluate the displacement damage ability of an incident particles. The bigger the ratio of Dd/(Dd+Di), in the sensitive region caused by incident particles, the severer the displacement damage, and thus showing an obvious feature of displacement damage for bipolar devices. The displacement damage caused by various particles can be normalized by using a displacement dose equivalent method based on the NIEL in the sensitive region.It is shown that under the exposure of 70keV and 110keV electrons and 70keV protons, the change in the reciprocal of the current gain of bipolar transistors increases and is gradually saturated with increasing the fluence, the saturation is induced by ionization damage. Under a given fluence, due to their different abilities for ionization damage, the different type particles with various energies would lead to different ionization damage magnitudes. Based on the theoretical calculation and analyses on the electric property degradation, it is indicated that the larger the ionization dose per unit fluence of incident particle, the smaller the ionization damage magnitude for the bipolar transistors.During the exposure of charged particles, it is observed that the influence of bias condition on the ionization and displacement damage is different. If voltage on the base-emitter junction is forward, the exhausted region becomes narrow, resulting in weaker effect of ionization damage on the bipolar transistors. On the contrary, the ionization damage gives stronger effect on the transistors. The diffence in the bias condition gives little contribution to the bulk defects caused by displacement damage. However, when the the base-emitter voltage is forward, the electric charges will be injected into the base region, inducing an annealing effect on the displacement damage.Through the combined irradiation experiments of protons and electrons, it is revealed that the bipolar transistors show a synergistic effect of displacement damage with ionization damage. Under the combined exposure of 170keV protons and 110keV (or 70keV) electrons, the displacement damage dominates the current gain degradation for the transistors, and the ionization gives both annealing and aggravation effect on the displacement damage. The photocurrent induced by ionization damage in Si bulk will passivate a portion of the bulk defects, inducing the annealing effects. Meanwhile, the interface state and oxide charge caused by ionization damage in the Si/SiO2 interface and oxide layer will move the peak of the surface recombination current into Si bulk, leading to more server displacement damage. The trend of degradation of current gain, caused by the synergistic effect of displacement damage with ionization damage, for NPN and PNP transistors is the same.Based on the calculation of space environment parameters, the ground-based simulation experiments and the analyses of radiation effects and mechanisms, a prediction method is given for the electric degradation of bipolar devices in orbit, in which all the contributions can be considered for the ionization and displacement effects induced by different types of charged particles with various energies. This method could be used in practice.更多还原