Electron beam lithography on vertical side faces of micrometer-order Si block
(Color online) Fabrication process for creating 3D nanostructures in Si. Steps (a)–(g) were performed. For steps (i) and (j), we have already confirmed that large-angle ion etching is possible (Ref. 2).
(Color online) Cross-sectional SEM images of resist film spin-coated on a Si block using (a) conventional and (b), (c) our optimized solutions. The concentrations of the PMMA resist solutions are (a) 3.3, (b) 1.2, and (c) 0.7 wt. %. The insets indicate measured thickness vs the Z position for the left side (solid lines) and right side (broken lines). The vertical gray lines in the insets indicate averages [171 nm (b) and 120 nm (c)] and their ±20%. (b) Reprinted with permission from K. Yamazaki and H. Yamaguchi, Appl. Phys. Express 3, 106501 (2010). Copyright 2010, The Japan Society of Applied Physics.
(Color online) (a) Top-view SEM image taken after patterning on the side faces and (b) distributions of measured thickness on side A (solid line) and side B (broken line). The horizontal lines indicate 370 nm ±15%.
(Color online) Electron trajectories obtained by Monte Carlo simulation for EB writing on a Si block from the side.
(Color online) Simulated distribution of energy deposited in resist when dense lines are written (a) on both side faces of a Si block and (b) on a flat Si substrate.
Pairs of SEM images of dense patterns delineated on opposite side faces of Si blocks. For (a) and (b), the height of the written patterns is adjusted. Images (c) and (d) are for sides A and B in Fig. 3(a), where the height of the written patterns is larger than the block height. [The arrows of A and B in Fig. 3(a) do not indicate the positions but the directions of the observations.] Images (e) and (f) are of horizontal lines.
(Color online) (a) Cross-sectional schematic showing the model used for estimating ΔE and ΔSγ. (b) Calculated distribution of in the triangular cross section.
Viscosity η and surface tension γ of PMMA solution (temperature in °C).
Estimated values of ΔE and ΔSγ per unit length (J/m).
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