Origin and characteristics of alpha-particle-induced permanent junction leakage

The origin and characteristics of the permanent junction leakage caused by alpha-particle irradiation and its impact on the reliability of DRAM cells are investigated. The following results are obtained. (1) Three types of leakage are important in the alpha-particle-induced junction leakage current: the generation current that is mainly caused by divacancies (VV) induced in p-type substrates, the enhanced peripheral leakage current due to weak avalanche, and the peripheral leakage current caused by buildup of surface states. (2) The dominant component in the three types of leakage is determined by the reverse bias across the junction during both irradiation and measurements. (3) The hard error rates in the DRAM cell caused by the alpha-particle-induced junction leakage are strongly related to the alpha-particle-induced soft-error rates. As long as the DRAM cell is designed to provide high immunity to the soft errors, the hard errors are not a serious problem.<
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