Radiation Effects Microscopy and Charge Transport Simulations

The passage of energetic ions through semiconductor material results in the creation of electron-hole pairs that can introduce electrical charge into sensitive nodes of electronic devices. This charge, if of sufficient magnitude and duration, can cause the transient or permanent failure of a device. The measurement and modeling of charge collection processes is vital for validating predictive design simulation codes. Radiation effects microscopy is used to experimentally replicate the conditions that are simulated by three dimensional charge transport calculations of a circuit's response to a single ion strike at a specific circuit location. This paper describes two radiation microscopy techniques used in studying integrated circuits, the effect of ion-induced damage on these techniques, and the use of these techniques in validating three dimensional charge transport simulations. Examples of simulation verification are shown for the TA788 16K SRAM; this device is a 16K test version of the radiation hardened SA3953 256K SRAM fabricated using 0.5 micron design rules iln Sandia's CMOS 6R process.