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Title: Fabrication of Very-High-Aspect-Ratio Microstructures in Complex Patterns by Photoelectrochemical Etching

Abstract

We have fabricated very-high-aspect-ratio (VHAR) silicon and metal microstructures in complex geometric patterns. The recently developed surfactant-added tetramethylammonium hydroxide etching allows the formation of V-grooves in any pattern, i.e., not limited by the crystal direction, on a silicon surface. As the resulting sharp pits allow very deep photoelectrochemical etching, VHAR silicon microstructures (4-mu m-wide and over-300-mu m-deep trenches) are successfully fabricated in complex patterns (spiral and zigzag demonstrated), overcoming the prevailing limitations of simple pores and straight trenches. Furthermore, by filling the VHAR silicon mold with nickel and removing the silicon, high-aspect-ratio metal microstructures of complex patterns are also obtained. These VHAR microstructures in complex patterns, which are structurally much stronger than the simple posts and straight plates, overcome the stiction problem even when densely populated. [2012-0042]

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
OSTI Identifier:
1211394
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Microelectromechanical Systems; Journal Volume: 21; Journal Issue: 6
Country of Publication:
United States
Language:
English

Citation Formats

Sun, GY, Zhao, X, and Kim, CJ. Fabrication of Very-High-Aspect-Ratio Microstructures in Complex Patterns by Photoelectrochemical Etching. United States: N. p., 2012. Web. doi:10.1109/JMEMS.2012.2211574.
Sun, GY, Zhao, X, & Kim, CJ. Fabrication of Very-High-Aspect-Ratio Microstructures in Complex Patterns by Photoelectrochemical Etching. United States. doi:10.1109/JMEMS.2012.2211574.
Sun, GY, Zhao, X, and Kim, CJ. 2012. "Fabrication of Very-High-Aspect-Ratio Microstructures in Complex Patterns by Photoelectrochemical Etching". United States. doi:10.1109/JMEMS.2012.2211574.
@article{osti_1211394,
title = {Fabrication of Very-High-Aspect-Ratio Microstructures in Complex Patterns by Photoelectrochemical Etching},
author = {Sun, GY and Zhao, X and Kim, CJ},
abstractNote = {We have fabricated very-high-aspect-ratio (VHAR) silicon and metal microstructures in complex geometric patterns. The recently developed surfactant-added tetramethylammonium hydroxide etching allows the formation of V-grooves in any pattern, i.e., not limited by the crystal direction, on a silicon surface. As the resulting sharp pits allow very deep photoelectrochemical etching, VHAR silicon microstructures (4-mu m-wide and over-300-mu m-deep trenches) are successfully fabricated in complex patterns (spiral and zigzag demonstrated), overcoming the prevailing limitations of simple pores and straight trenches. Furthermore, by filling the VHAR silicon mold with nickel and removing the silicon, high-aspect-ratio metal microstructures of complex patterns are also obtained. These VHAR microstructures in complex patterns, which are structurally much stronger than the simple posts and straight plates, overcome the stiction problem even when densely populated. [2012-0042]},
doi = {10.1109/JMEMS.2012.2211574},
journal = {Journal of Microelectromechanical Systems},
number = 6,
volume = 21,
place = {United States},
year = 2012,
month =
}
  • No abstract prepared.
  • We report on the formation of ultra-high aspect ratio nanopores in silicon bulk material using photo-assisted electrochemical etching. Here, n-type silicon is used as anode in contact with hydrofluoric acid. Based on the local dissolution of surface atoms in pre-defined etching pits, pore growth and pore diameter are, respectively, driven and controlled by the supply of minority charge carriers generated by backside illumination. Thus, arrays with sub-100 nm wide pores were fabricated. Similar to macropore etching, it was found that the pore diameter is proportional to the etching current, i.e., smaller etching currents result in smaller pore diameters. To find themore » limits under which nanopores with controllable diameter still can be obtained, etching was performed at very low current densities (several μA cm{sup −2}). By local etching, straight nanopores with aspect ratios above 1000 (∼19 μm deep and ∼15 nm pore tip diameter) were achieved. However, inherent to the formation of such narrow pores is a radius of curvature of a few nanometers at the pore tip, which favors electrical breakdown resulting in rough pore wall morphologies. Lowering the applied bias is adequate to reduce spiking pores but in most cases also causes etch stop. Our findings on bulk silicon provide a realistic chance towards sub-10 nm pore arrays on silicon membranes, which are of great interest for molecular filtering and possibly DNA sequencing.« less
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  • At present, the fabrication of patterns with deep submicron and nanometer dimensions has attracted strong attention for the study of nanoscale devices. A method for fabrication of fine patterns by conventional technologies such as optical lithography, trilayer resist, magnetron reactive ion etching (MRIE), and plasma enhanced chemical vapor deposition (PECVD) is described. Using the sidewall process for fine pattern transfer and magnetron reactive ion etching, deep submicron and nanometer patterns with high aspect ratio have been prepared. 3 refs., 6 figs.
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