Certification of Parts for Space With the Variable Depth Bragg Peak Method

The Variable Depth Bragg Peak (VDBP) method uses long-range high-energy heavy ions to measure the Single Event Effect (SEE) cross-section as a function of linear energy transfer (LET(Si)) for commercially packaged integrated circuits with sensitive volumes at unknown depths. This is done by lowering the energy of the ions incident on the device-under-test (DUT) in steps, by insertion of polyethylene degraders of increasing thickness, until the maximum event cross-section is observed, which indicates that ions with the highest average LET(Si) (at the peak of the Bragg Peak) are depositing energy in the sensitive volume. The present paper describes use of the VDBP method to test for single event latchup (SEL) in packaged parts that do and do not fail catastrophically and to certify a device by assuring that every depth in the packaged device is exposed to a fluence of ions with average LET(Si) values greater than a specified value, in this case 60 MeV/mg/cm².