Figure 6: Effects of probe sharpening on patterning capabilities.
From: Field-directed sputter sharpening for tailored probe materials and atomic-scale lithography
Each hydrogen-resist pattern includes a sequence of lines corresponding to sample biases from lower left to upper right of 4, 4.5, 5, 5.5, 6 and 6.5 V with constant tunnelling current of 2 nA and line dose of 2×10−3 C cm−1. STM images are collected with a sample bias of −2 V and a current set point of 50 pA. All scale bars, 30 nm. (a) Transmission electron micrograph of an exceptionally sharp tungsten probe produced by ECE. (b) A representative pattern on the Si(100) 2×1:H surface written by electron-stimulated desorption of hydrogen using the ECE probe of a. (c) Transmission electron micrograph of the probe following an FDSS sharpening procedure (1.4 keV ion energy, Vr=0.286, 38 min). (d) A representative pattern created with this FDSS-generated probe. (e) Transmission electron micrograph of the same probe following control experiment sputtering (1.0 keV ion energy, Vr=0, 60 min). (f) A representative pattern created with the control probe. (g) Spatial distribution of desorption probability for FDSS and CSE probe patterns at 5.5 and 4.5 V sample bias. In order of decreasing width, CSE 5.5 V pattern is shown in red, FDSS 5.5 V pattern in green, CSE 4.5 V pattern in black and FDSS 4.5 V pattern in blue. (h) Further patterning results from multiple probes sharpened by ECE, FDSS and CSE.
