Heavy-ion and pulsed-laser single event effects in 130-nm CMOS-based thin/thick gate oxide anti-fuse PROMs

Single event effects of 1-T structure programmable read-only memory(PROM) devices fabricated with a 130-nm complementary metal oxide semiconductorbased thin/thick gate oxide anti-fuse process were investigated using heavy ions and a picosecond pulsed laser. The cross sections of a single event upset(SEU) for radiationhardened PROMs were measured using a linear energy transfer(LET) ranging from 9.2 to 95.6 MeV cm^2mg^(-1).The result indicated that the LET threshold for a dynamic bit upset was ～ 9 MeV cm^2mg^(-1), which was lower than the threshold of ～ 20 MeV cm^2mg^(-1) for an address counter upset owing to the additional triple modular redundancy structure present in the latch. In addition, a slight hard error was observed in the anti-fuse structure when employing209 Bi ions with extremely high LET values(～ 91.6 MeV cm^2mg^(-1)) and large ion fluence(～ 1×10~8 ions cm^(-2)). To identify the detailed sensitive position of a SEU in PROMs, a pulsed laser with a 5-μm beam spot was used to scan the entire surface of the device.This revealed that the upset occurred in the peripheral circuits of the internal power source and I/O pairs rather than in the internal latches and buffers. This was subsequently confirmed by a ^(181)Ta experiment. Based on the experimental data and a rectangular parallelepiped model of the sensitive volume, the space error rates for the used PROMs were calculated using the CRèME-96 prediction tool. The results showed that this type of PROM was suitable for specific space applications, even in the geosynchronous orbit.

Influences of total ionizing dose on single event effect sensitivity in floating gate cells

The influences of total ionizing dose （TID） on the single event effect （SEE） sensitivity of 34-nm and 25-nm NAND flash memories are investigated in this paper. The increase in the cross section of heavy-ion single event upset （SEU） in memories that have ever been exposed to TID is observed, which is attributed to the combination of the threshold voltage shifts induced by 7-rays and heavy ions. Retention errors in floating gate （FG） cells after heavy ion irradiation are observed. Moreover, the cross section of retention error increases if the memory has ever been exposed to TID. This effect is more evident at a low linear energy transfer （LET） value. The underlying mechanism is identified as the combination of the defects induced by 7-rays and heavy ions, which increases the possibility to constitute a multi-trap assisted tunneling （m- TAT） path across the tunnel oxide.