Experimental Investigation of Single-Event Transient Waveforms Depending on Transistor Spacing and Charge Sharing in 65-nm CMOS

Single-event cross sections of four inverter chains, with uniform inverter spacing ranging from 120 nm to $4~\mu \text{m}$ , were experimentally measured and compared. These inverter chains were irradiated using a focused ion beam. Full analog waveforms of responses were sensed using on-chip wide-bandwidth analog multiplexers. Cross sections are examined with respect to pulse heights and pulse widths, for direct-hit waveforms as well as for waveforms propagated through the chain. The influence of ion hit position and charge sharing effects on the initial shape and propagation of the single-event transients (SETs) was analyzed. We have observed a considerable reduction of cross section for tightly spaced inverters, for both direct hits and propagated SETs.