Milling yield estimation in focused ion beam milling of two-layer substrates

Abstract

The material removal rate or milling yield of using the focused ion beam (FIB) for milling two-layer substrates is studied. The preparation of the two-layer substrate is first presented and is followed by the procedure on conducting the milling experiment. The effects of the dwell time on the milling rate and the final profiles of the milled structures are investigated. The atomic force microscope (AFM) is applied for measuring the profiles of the milled channels. Based on the AFM measurements, a relatively simple formula is developed to estimate the milling yield, which is normally dictated by both the characteristics of sputtering and redeposition for channel milling. The estimated milling rates are then compared with the corresponding sputtering yields predicted using a different numerical scheme. The milling rates obtained presently are discovered to be roughly equal to the predicted normal-incidence sputtering yields for both layers involved. Consistency is found as the present findings are compared with other milling studies on single-layer substrates. Finally, concluding remarks that summarize the present work and suggest future work on FIB milling are included.

Design criteria of neuron/electrode interface. The focused ion beam technology as an analytical method to investigate the effect of electrode surface morphology on neurocompatibility

“…In fact, in these cases, the main limitation is the re-deposition of sputtered material. Sputtered atoms are re-deposited around the patterns and they produce a distortion of pattern profiles and of the real sputtering rate (Langford et al, 2002;Tseng et al, 2005). An example of FIB surface modification is shown in Fig.…”

The role of metal layers in the formation of metal–silicon hybrid nanoneedle arrays

“…[13][14][15]17 For the silicon substrate, the reported investigations of FIB etching techniques emphasize the volume removed to estimate the milling yield, rather than the nanostructured surface prole. [18][19][20][21] The ridges or nanodots are formed around the trench banks and are suggested to be due to the redeposition or swelling effect during ion milling. 18,22,23 We reported a hybrid nanostructure consisting of a nanodot and nanoneedle that shows excellent gas sensitivity.…”

“…[18][19][20][21] The ridges or nanodots are formed around the trench banks and are suggested to be due to the redeposition or swelling effect during ion milling. 18,22,23 We reported a hybrid nanostructure consisting of a nanodot and nanoneedle that shows excellent gas sensitivity. 24 However, the role the metal layers play in the formation of the metal-silicon hybrid nanoneedle arrays has not been sufficiently explored.…”

Ordered hybrid nanoneedle arrays for gas sensing

“…Thus the ion sputtered particles probably recoil back onto the solid causing a redeposition [57]. The effect will complicate the estimation of milling rate, because the volume of redeposition is not only impacted by both the pattern or sputtered geometry, but also the material properties, such as sticking coefficient and binding energy [56,68]. In case of fabrication of a nanoneedle array, the material accumulation on the ridge, rather than the total material removal during engraving, has to be emphasized, as shown in Figure 2.18 [137].…”

“…Ion beam in FIB system carries high energy enabling the materials removal from the substrates through ion sputtering[68][69][70][71]. This beam incident to the substrates can also rearrange the atoms to form different topographic structures on the surfaces.…”