Two‐Dimensional Profile Simulation of Focused Ion‐Beam Milling of LSI

Abstract

Focused ion‐beam milling has recently been used for modifying and debugging LSIs, where precise depth control is required. In order to analyze the effects of scanning width and redeposition on hole depth, we have developed a two‐dimensional milling profile simulator, which takes redeposition into consideration. The results of the simulation are in good agreement with our experiments. It has been demonstrated that when the beam scanning width is less than the beam tail diameter, the milling depth declines due to dose deficiency. When the aspect ratio (depth/width) is high, the depth is less than proportional to the dose due to redeposition.

Fabrication of SU-8 based nanopatterns and their use as a nanoimprint mold

“…Under this operation condition, the ions tail would be as far as 70 nm from the beam center 26 . According to Itoh et al 27 , where the scanning width, W, is larger than ion tail diameter, dtail, the area W − d gives a maximum ion dose as we anticipated. However, if scanning width is smaller than the ion tail diameter, the constant dosed area disappears and the dose in scanning area will be lower than maximum ion dose.…”

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

“…It is well accepted that the formation of nanostructures by ion milling depends on both the target material system and the incident beam parameters. 18,[20][21][22][23]25,31 Two beam parameters were tested with the formed patterns, shown in Fig. S4, † where the nanodots fail to be preserved during ion irradiation.…”

“…[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.…”

Ordered hybrid nanoneedle arrays for gas sensing

“…For the incident ion beam, the Ga + current density J [Acm -2 ] on each pixel yields a two-dimensional Gaussian distribution, which can be expressed as where I stands for the total beam current, r represents the distance of the concerned point to the beam center on sample surface, and σ is the statistic deviation. In the process condition of this work (a beam current up to 2.8 nA), σ is evaluated as 66 nm from the FIB controlling system, and the tail radius can be assumed to be 5σ [70], which just covers the tip position of nanoneedles. For each pixel, the dwell time t d is 10 -6 sec as default.…”

“…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.…”