基于单/双层壁电离室的强钴源低能γ成分评估方法
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摘要
利用重金属工艺可提高器件可靠性,低能γ将使器件高Z/低Z界面附近产生剂量增强效应,影响器件抗辐射性能评估。介绍了一种强钴源低能散射γ成分评价方法,利用铝单层室壁/金铝双层室壁平板型电离室辐射电流比值对γ能量敏感的特性,通过比较电流比值实测与参考值的差异,估计散射γ(≤300 ke V)成分是否过多,典型钴源能谱计算结果表明:参考值可取为2.8。研制了量程为0.01~2.3 Gy·s~(-1)(Si)的电离室探头,搭建了长距离辐射电流测量系统。单板钴源实验结果表明:空场条件和铅铝容器(散射抑制)内辐射电流比值实测结果与预期相符,方法可行;能够检验能谱硬化技术的有效性;可从剂量角度关联不同辐射场或相同辐射场不同辐照工位。
[Background] Heavy metal process is widely used to improve the reliability of electronic devices, which introduces interface formed by high Z and low Z material. There will be dose enhancement effect within region near such interface when exposing to low energy γ-ray field. This phenomenon could affect the reliability of hardness assurance tests. [Purpose] A method was introduced to evaluate the proportion of low energy scattering γ-ray within high dose rate irradiation field formed by cobalt source. [Methods] Two types of ionization chambers were designed, which utilize single layer Al(aluminum) wall and double layers Au(gold)/Al wall respectively. The γ-ray induced current of the latter ionization chamber varied more rapidly with the change of γ-ray energy than the former one. Consequently, the ratio of those two currents was sensitive to γ-ray energy, and the variation between measured and reference value of ratio could indicate whether the proportion of low energy γ-ray was over expectation obviously. [Results] It was advised that the reference value could be set as 2.8 based on analysis of typical energy spectrums of cobalt source. In addition, an ionization chamber dosimeter system with the range of 0.01~2.3 Gy·s~(-1)(Si) was designed with which the ratios were measured in free field and Pb(lead)/Al box reducing the amount of low energy γ-ray. There was an agreement between experimental and calculated results. [Conclusion] The method is effective for evaluating the proportion of scattering γ-ray and the effectiveness of spectral hardening technology. Furthermore, it could help correlate different irradiation fields or irradiation positions within specific irradiation field from the aspect of irradiation dose.
[Background] Heavy metal process is widely used to improve the reliability of electronic devices, which introduces interface formed by high Z and low Z material. There will be dose enhancement effect within region near such interface when exposing to low energy γ-ray field. This phenomenon could affect the reliability of hardness assurance tests. [Purpose] A method was introduced to evaluate the proportion of low energy scattering γ-ray within high dose rate irradiation field formed by cobalt source. [Methods] Two types of ionization chambers were designed, which utilize single layer Al(aluminum) wall and double layers Au(gold)/Al wall respectively. The γ-ray induced current of the latter ionization chamber varied more rapidly with the change of γ-ray energy than the former one. Consequently, the ratio of those two currents was sensitive to γ-ray energy, and the variation between measured and reference value of ratio could indicate whether the proportion of low energy γ-ray was over expectation obviously. [Results] It was advised that the reference value could be set as 2.8 based on analysis of typical energy spectrums of cobalt source. In addition, an ionization chamber dosimeter system with the range of 0.01~2.3 Gy·s~(-1)(Si) was designed with which the ratios were measured in free field and Pb(lead)/Al box reducing the amount of low energy γ-ray. There was an agreement between experimental and calculated results. [Conclusion] The method is effective for evaluating the proportion of scattering γ-ray and the effectiveness of spectral hardening technology. Furthermore, it could help correlate different irradiation fields or irradiation positions within specific irradiation field from the aspect of irradiation dose.
引文
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2 牟维兵,陈盘训.X射线在重金属-二氧化硅界面的剂量增强的模拟计算[J].强激光与粒子束,2001,13(1):15-18.MU Weibing,CHEN Panxun.Simulative calculation of the dose enhancement factor of W-Si O2 and Ta-Si O2interface[J].High Power Laser and Particle Beams,2001,13(1):15-18.
3 吴正新,何承发,陆妩,等.X射线对金硅界面剂量增强效应的模拟研究[J].核技术,2013,36(6):060201.DOI:10.11889/j.0253-3219.2013.hjs.36.060201.WU Zhengxin,HE Chengfa,LU Wu,et al.Monte Carlo simulation of dose enhancement effect of X-ray at Au/Si interface[J].Nuclear Techniques,2013,36(6):060201.DOI:10.11889/j.0253-3219.2013.hjs.36.060201.
4 郭红霞.X射线、γ射线引起不同界面材料剂量增强效应的测量及理论模拟[D].西安:西安电子科技大学,2002.GUO Hongxia.Numerical simulation of ionizing radiation effects and study on the X-ray andγ-ray dose enhancement effects for integrated circuit[D].Xi’an:Xidian University,2002.
5 Simons M,Pease R L,Fleetwood D M,et al.Dose enhancement in room cobalt-60 source[J].IEEE Transactions on Nuclear Science,1997,44(6):2052-2057.DOI:10.1109/23.658990.
6 郭红霞,陈雨生,张义门,等.双层膜结构测量CMOS器件X射线相对剂量增强因子及其理论模拟[J].核电子学与探测技术,2002,22(1):47-51.GUO Hongxia,CHEN Yusheng,ZHANG Yimen,et al.Measurement of X-ray relative dose-enhancement factor for CMOS device using bi-laminate structure and its simulation[J].Nuclear Electronics&Detection Technology,2002,22(1):47-51.
7 中华人民共和国国家军用标准.GJB 548B-2005:微电子器件试验方法和程序[S].2005.People’s Republic of China National Military Standard.GJB 548B-2005:Test methods and procedures for microelectronic device[S].2005.
8 Wall J A,Burke E A.Dose distributions at and near the interface of different materials exposed to cobalt-60gamma radiation[R].Air Force Cambridge Research Laboratories,AD-A010 427,1975.
9 何承发,巴维真,吴勤之,等.60Coγ射线在界面附近金中的剂量分布[J].核技术,1997,20(3):143-147.HE Chengfa,BA Weizhen,WU Qinzhi,et al.Dose profiles of 60Co gamma rays in gold near interfaces with other materials[J].Nuclear Techniques,1997,20(3):143-147.
10 Attix F H,著.雷家荣,崔高显,译.放射物理和辐射计量学导论[M].北京:北京原子能出版社,2013:178-266.Attix F H,ed.LEI Jiarong,CUI Gaoxian,tran.Introduction to radiology and radiation metrology[M].Beijing:Beijing Atomic Energy Publishing House,2013:178-266.
11 李磊,李晓燕,蒋树斌,等.基于改进型贪心算法的单板源源棒排列优化[J].核技术,2015,38(10):100204.DOI:10.11889/j.0253-3219.2015.hjs.38.100204.LI Lei,LI Xiaoyan,JIANG Shubin,et al.Optimization of source pencil deployment of single-plate irradiation facility based on improved greedy algorithm[J].Nuclear Techniques,2015,38(10):100204.DOI:10.11889/j.0253-3219.2015.hjs.38.100204.
12 美国材料与试验协会.使用Co-60源的硅电子设备的辐射硬性试验的最小剂量测定错误标准规程[S].ASTM E1249-2000(2005),2005.American Society for Testing and Materials.Standard practice for minimizing dosimetry errors in radiation hardness testing of silicon electronic devices using Co-60sources[S].ASTM E1249-2000(2005),2005.
13 牟维兵,徐曦.剂量增强理论计算与实验测量[C].中国工程物理研究院第七届电子技术青年学术交流会,绵阳,2005.MU Weibing,XU Xi.Calculation and experimental measurement of dose enhancement factor[C].The 7th Young Academic Communication in Electronic Techniques of CAEP,Mianyang,2005.
14 牟维兵,陈盘训.电子器件不同材料界面对X射线的响应[C].第11届全国核电子学与核探测技术学术年会,厦门,2002.MU Weibing,CHEN Panxun.The X-ray response near the different interface of electronic devices[C].The Proceeding of 11th National Academic Annual Reference in Nuclear Electronics and Nuclear Detection Technology,Xiamen,2002.
15 周银行,马玉刚.金属-Si界面剂量增强效应的模拟研究[J].核电子学与探测技术,2009,23(5):1012-1016.ZHOU Yinhang,MA Yugang.Monte Carlo simulation of dose enhancement effect of semiconductor-metal interface[J].Nuclear Electronics&Detection Technology,2009,23(5):1012-1016.
16 郭红霞,陈雨生,张义门,等.稳态、瞬态X射线辐照引起的互补性金属氧化物半导体器件剂量增强效应研究[J].物理学报,2001,50(12):2279-2283.DOI:10 .3321/j.issn:1000-3290.2001.12.001.GUO Hongxia,CHEN Yusheng,ZHANG Yimen,et al.Study of relative dose-enhancement effects on CMOS device irradiated by steady-state and transient pulsed X-rays[J].Acta Physica Sinica,2001,50(12):2279-2283.DOI:10.3321/j.issn:1000-3290.2001.12.001.
2 牟维兵,陈盘训.X射线在重金属-二氧化硅界面的剂量增强的模拟计算[J].强激光与粒子束,2001,13(1):15-18.MU Weibing,CHEN Panxun.Simulative calculation of the dose enhancement factor of W-Si O2 and Ta-Si O2interface[J].High Power Laser and Particle Beams,2001,13(1):15-18.
3 吴正新,何承发,陆妩,等.X射线对金硅界面剂量增强效应的模拟研究[J].核技术,2013,36(6):060201.DOI:10.11889/j.0253-3219.2013.hjs.36.060201.WU Zhengxin,HE Chengfa,LU Wu,et al.Monte Carlo simulation of dose enhancement effect of X-ray at Au/Si interface[J].Nuclear Techniques,2013,36(6):060201.DOI:10.11889/j.0253-3219.2013.hjs.36.060201.
4 郭红霞.X射线、γ射线引起不同界面材料剂量增强效应的测量及理论模拟[D].西安:西安电子科技大学,2002.GUO Hongxia.Numerical simulation of ionizing radiation effects and study on the X-ray andγ-ray dose enhancement effects for integrated circuit[D].Xi’an:Xidian University,2002.
5 Simons M,Pease R L,Fleetwood D M,et al.Dose enhancement in room cobalt-60 source[J].IEEE Transactions on Nuclear Science,1997,44(6):2052-2057.DOI:10.1109/23.658990.
6 郭红霞,陈雨生,张义门,等.双层膜结构测量CMOS器件X射线相对剂量增强因子及其理论模拟[J].核电子学与探测技术,2002,22(1):47-51.GUO Hongxia,CHEN Yusheng,ZHANG Yimen,et al.Measurement of X-ray relative dose-enhancement factor for CMOS device using bi-laminate structure and its simulation[J].Nuclear Electronics&Detection Technology,2002,22(1):47-51.
7 中华人民共和国国家军用标准.GJB 548B-2005:微电子器件试验方法和程序[S].2005.People’s Republic of China National Military Standard.GJB 548B-2005:Test methods and procedures for microelectronic device[S].2005.
8 Wall J A,Burke E A.Dose distributions at and near the interface of different materials exposed to cobalt-60gamma radiation[R].Air Force Cambridge Research Laboratories,AD-A010 427,1975.
9 何承发,巴维真,吴勤之,等.60Coγ射线在界面附近金中的剂量分布[J].核技术,1997,20(3):143-147.HE Chengfa,BA Weizhen,WU Qinzhi,et al.Dose profiles of 60Co gamma rays in gold near interfaces with other materials[J].Nuclear Techniques,1997,20(3):143-147.
10 Attix F H,著.雷家荣,崔高显,译.放射物理和辐射计量学导论[M].北京:北京原子能出版社,2013:178-266.Attix F H,ed.LEI Jiarong,CUI Gaoxian,tran.Introduction to radiology and radiation metrology[M].Beijing:Beijing Atomic Energy Publishing House,2013:178-266.
11 李磊,李晓燕,蒋树斌,等.基于改进型贪心算法的单板源源棒排列优化[J].核技术,2015,38(10):100204.DOI:10.11889/j.0253-3219.2015.hjs.38.100204.LI Lei,LI Xiaoyan,JIANG Shubin,et al.Optimization of source pencil deployment of single-plate irradiation facility based on improved greedy algorithm[J].Nuclear Techniques,2015,38(10):100204.DOI:10.11889/j.0253-3219.2015.hjs.38.100204.
12 美国材料与试验协会.使用Co-60源的硅电子设备的辐射硬性试验的最小剂量测定错误标准规程[S].ASTM E1249-2000(2005),2005.American Society for Testing and Materials.Standard practice for minimizing dosimetry errors in radiation hardness testing of silicon electronic devices using Co-60sources[S].ASTM E1249-2000(2005),2005.
13 牟维兵,徐曦.剂量增强理论计算与实验测量[C].中国工程物理研究院第七届电子技术青年学术交流会,绵阳,2005.MU Weibing,XU Xi.Calculation and experimental measurement of dose enhancement factor[C].The 7th Young Academic Communication in Electronic Techniques of CAEP,Mianyang,2005.
14 牟维兵,陈盘训.电子器件不同材料界面对X射线的响应[C].第11届全国核电子学与核探测技术学术年会,厦门,2002.MU Weibing,CHEN Panxun.The X-ray response near the different interface of electronic devices[C].The Proceeding of 11th National Academic Annual Reference in Nuclear Electronics and Nuclear Detection Technology,Xiamen,2002.
15 周银行,马玉刚.金属-Si界面剂量增强效应的模拟研究[J].核电子学与探测技术,2009,23(5):1012-1016.ZHOU Yinhang,MA Yugang.Monte Carlo simulation of dose enhancement effect of semiconductor-metal interface[J].Nuclear Electronics&Detection Technology,2009,23(5):1012-1016.
16 郭红霞,陈雨生,张义门,等.稳态、瞬态X射线辐照引起的互补性金属氧化物半导体器件剂量增强效应研究[J].物理学报,2001,50(12):2279-2283.DOI:10 .3321/j.issn:1000-3290.2001.12.001.GUO Hongxia,CHEN Yusheng,ZHANG Yimen,et al.Study of relative dose-enhancement effects on CMOS device irradiated by steady-state and transient pulsed X-rays[J].Acta Physica Sinica,2001,50(12):2279-2283.DOI:10.3321/j.issn:1000-3290.2001.12.001.