Fib delayering endpoint detection by monitoring sputtered materials using rga

Abstract

A method of milling a sample that includes a first layer formed over a second layer, where the first and second layers are different materials, the method comprising: milling the region of the sample by scanning a focused ion beam over the region a plurality of iterations in which, for each iteration, the focused ion beam removes material from the sample generating byproducts from the milled region; detecting, during the milling, the partial pressures of one or more byproducts with a residual gas analyzer positioned to have a direct line of sight to the milled region; generating, in real-time, an output detection signal from the residual gas analyzer indicative of an amount of the one or more byproducts detected; and stopping the milling based on the output signal.