氧化层厚度对NPN双极管辐射损伤的影响

研究了不同氧化层厚度的两种国产NPN双极晶体管在高低剂量率下的辐射效应和退火特性。结果显示,随总剂量的增加,晶体管基极电流增大,电流增益下降,且薄氧化层的晶体管比常规厚氧化层的晶体管退化更严重。另外,两种NPN晶体管均表现出明显的低剂量率损伤增强效应。本文对各种实验现象的损伤机理进行了分析。     

不同偏置条件下PMOSFETs的剂量率效应研究

研究了不同剂量率、不同偏置条件下,PMOSFETs的辐照响应特性;并对高剂量率辐照后的器件进行了与低剂量率辐照等时的室温退火。结果表明,随着剂量率的降低,PMOSFETs阈值电压的漂移更加明显;不同偏置条件、不同剂量率范围内表现出TDE和ELDRS两种不同的剂量率效应。利用亚阈分离技术对影响阈值电压漂移的氧化物陷阱电荷和界面态进行了详细的机理分析,认为ELDRS效应的产生是由界面态密度的差异导致的。     

10位双极数模转换器的电离辐射效应

研究了国产互补双极工艺生产的数模转换器(D/A转换器)在不同偏置和不同剂量率条件下的电离辐射效应及退火特性。研究结果表明:D/A转换器对偏置条件和辐照剂量率都很敏感。大剂量率辐照时,电路功能正常,各功能参数变化较小;而在低剂量率辐照情况下,各参数变化显著,超出器件允许范围,器件功能失效。因此,D/A转换器表现出明显的低剂量率辐射损伤增强效应(ELDRS)。零偏时,D/A转换器功能参数损伤变化更加严重。最后,结合边缘电场效应和空间电荷模型对这种不同偏置和剂量率条件下的损伤机理进行了初步的探讨。     

The enhanced low dose rate sensitivity of a linear voltage regulator with different biases

A linear voltage regulator was irradiated by ⁶⁰Coγat high and low dose rates with two bias conditions to investigate the dose rate effect.The devices exhibit enhanced low dose rate sensitivity（ELDRS） under both biases. Comparing the enhancement factors between zero and working biases,it was found that the ELDRS is more severe under zero bias conditions.This confirms that the ELDRS is related to the low electric field in a bipolar structure. The reasons for the change in the line regulation and the maximum drive current were analyzed by combining the principle of linear voltage regulator with irradiation response of the transistors and error amplifier in the regulator. This may be helpful for designing radiation hardened devices.     

Non-equilibrium carrier capture, recombination and annealing in thick insulators and their impact on radiation hardness

This paper describes an approach to prediction of the thick insulators'' radiation response based on modeling of the charge yield, which is dependent on irradiation temperature, dose rate, and electric field magnitudes. Temperature behavior of the charge yield and degradation saturation due to the interface precursor depletion has been modeled and simulated. Competition between the time-dependent and true dose rate (ELDRS) effects has been simulated and discussed within a framework of the rate-equation-based mathematical model. It was shown that the precursor trap in the thick insulating oxides can be important at high dose rates. It was also shown that full filling of the shallow hole traps in the insulating oxide bulk can cause suppression of dose-rate sensitivity at relatively high dose rates, especially in thick insulators.     

Dose-rate dependence of radiation-induced interface trap density in silicon bipolar transistors

The key effects of ionizing radiation on silicon dioxide are described and computed. Inclusion of bimolecular electron–hole recombination is shown to produce a saturation of fixed charge at high total dose and to a reduction in interface trap density at high dose-rates. These results can explain the enhanced low dose rate sensitivity (ELDRS) phenomenon. These results also predict a new dose-rate dependence at very high dose rates.     

Dose-rate effects of low-dropout voltage regulator at various biases

<正>A low-dropout voltage regulator,LM2941,was irradiated by ~(60)Coγ-rays at various dose rates and biases for investigating the total dose and dose rate effects.The radiation responses show that the key electrical parameters, including its output and dropout voltage,and the maximum output current,are sensitive to total dose and dose rates, and are significantly degraded at low dose rate and zero bias.The integrated circuits damage change with the dose rates and biases,and the dose-rate effects are relative to its electric field.