Experimental investigation of redeposition during focused ion beam milling of high speed steel

Focused ion beam (FIB) milling is the micro and nano scale manufacturing process, in which components are fabricated with the micro and nano scale resolution. Micro surgical instruments, micro machining tools, probes of scanning probe microscopy and various other small sized components are fabricated using FIB milling. Due to the favorable properties like hardness and wear resistance, high speed steel (HSS) is one of the choices to fabricate many small scale components. While fabricating small scale components, a part of removed material redeposit onto the machined surface, which is known as redeposition. One of the effects of redeposition is that it impairs dimensional accuracy of work material. HSS work material is investigated for the effect of redeposition during FIB milling and existing mathematical model of depth of sputtering has been modified to take into account the effect of redeposition. The ratio of rate of redeposition to the beam velocity has been evaluated for different beam velocities to validate the modified mathematical model of depth of sputtering and more accurate results of depth of sputtering are achieved with the modified model.

► FIB milling of high speed steel (HSS) has been performed.
► Redeposition of removed material on newly milled surface has been studied during FIB milling of HSS.
► Existing mathematical model of depth of sputtering has been modified to consider the redeposition of removed material.
► Modified mathematical model has been validated through experiments.
► Improvements have been found in modified mathematical model.