Measuring the Effect of FIB Diffusion Exposure/Damage with a Gallium Focused Ion Beam for Semiconductor Circuit Edit Applications

Shrinking transistor geometries present ongoing challenges for backside FIB circuit edit operations. The available space to gain access to critical signal lines has diminished to the order of hundreds of nanometers. Several previous works have shown that the diffusion of active devices can be exposed. This paper explores the effects of exposing and selectively damaging the active diffusion layer of advanced finFET process technology. STEM cross section images show that the devices are unaffected when the silicon substrate is on the order of 1-2ums. When the silicon substrate is removed to less than 100nm, the effect can be seen electrically on a set of ring oscillators.