A new approach to measuring the sensitive volume using a pulsed laser system

Recent work has shown that ions can be used to measure the depth and thickness of the sensitive volume in memory devices and that laser pulsing at a range of wavelengths also yields an estimate of the charge collection depth. In this paper it is shown that the laser technique can be extended to provide a detailed measurement of the sensitivity profile of a memory cell with respect to charge collection from an ionisation track. It is also shown, through analysis of pulsed laser SEU threshold measurements made at two wavelengths, that the charge collection depth for 1Mbit SRAM's appears to be significantly greater than the depth of the active region.