Combined AFM and laser lithography on hydrogen-passivated amorphous silicon

Journal of Applied Physics

et al. 1997

Optically induced oxidation of hydrogen-passivated silicon surfaces using a scanning near-field optical microscope was achieved with both uncoated and aluminum-coated fiber probes. Line scans on amorphous silicon using uncoated fiber probes display a three-peak profile after etching in potassium hydroxide. Numerical simulations of the electromagnetic field around the probe–sample interaction region are used to explain the experimental observations. With an aluminum-coated fiber probe, lines of 35 nm in width were transferred into the amorphous silicon layer.

Section: B Lithography With Aluminum-coated Fiber Probesmentioning

confidence: 99%

“…4,8 More recently, optically induced hydrogen desorption was reported. [9][10][11] In this article we discuss results obtained using a scanning near-field optical microscope ͑SNOM͒ 12 to generate an oxide mask on an amorphous silicon ͑a-Si͒ layer. Results for uncoated fiber probes are compared with those for aluminum-coated probes.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of hydrogen-passivated silicon surfaces by scanning near-field optical lithography using uncoated and aluminum-coated fiber probes

Madsen

Bozhevolnyi

Journal of Applied Physics

et al. 1997

“…The AFM is run in contact mode in air using a titanium-coated silicon nitride tip and applying a voltage between Ϫ5 V and Ϫ10 V for oxidation. 13 The entire process of defining contact pads and wires with an area of about 1 mm 2 by laser direct writing and the 200 nm wide and 2 m long nanowire by AFM writing can be completed in less than 1/2 h, which is fast enough to avoid substantial deterioration of the passivated surface in air. Based on our results, several improvements and variations can be envisaged.…”

Section: Laser Direct Writing Of Oxide Structures On Hydrogen-passivamentioning

confidence: 99%

Laser direct writing of oxide structures on hydrogen-passivated silicon surfaces

Müllenborn

Applied Physics Letters

Grey

et al. 1996

A focused laser beam has been used to induce oxidation of hydrogen-passivated silicon. The scanning laser beam removes the hydrogen passivation locally from the silicon surface, which immediately oxidizes in air. The process has been studied as a function of power density and excitation wavelength on amorphous and crystalline silicon surfaces in order to determine the depassivation mechanism. The minimum linewidth achieved is about 450 nm using writing speeds of up to 100 mm/s. The process is fully compatible with local oxidation of silicon by scanning probe lithography. Wafer-scale patterns can be generated by laser direct oxidation and complemented with nanometer resolution by scanning probe techniques. The combined micro- and nanoscale pattern can be transferred to the silicon in a single etching step by either wet or dry etching techniques.

“…In previous investigations, amorphous silicon on oxide has been used to form conducting nanostructures that are isolated from the underlying silicon substrate. 15 A crystalline silicon layer allows higher and more controlled conductivity of nanostructures. Also, crystalline silicon can be etched anisotropically, which can be advantageous for forming specific nanostructure shapes.…”

Section: Introductionmentioning

confidence: 99%

“…Another limitation is the considerable wear of the AFM tip when large areas are patterned. 15,16 Therefore there is a need for complementary low-resolution techniques, which are faster yet compatible with the AFM lithography. Conventional optical lithography is not always suitable due to the large step heights of structures thus defined that are difficult to scan by AFM.…”

Section: Introductionmentioning

confidence: 99%

New approaches to atomic force microscope lithography on silicon

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

1997

We have investigated new approaches to the formation of conducting nanowires on crystalline silicon surfaces using atomic force microscope (AFM) lithography. To increase processing speed and reduce wear of the AFM tip, large-scale structures are formed with a direct laser write setup, while the AFM is used to add the finer nanostructures. Both methods are based on selective oxidation of hydrogen-passivated silicon and subsequent etching to define conducting regions on the surface. This combined technique has previously been implemented on amorphous Si on oxide. To extend the technique to form crystalline silicon nanowires, we have used an arsenic implanted crystalline silicon layer on p-type Si, where the nanostructures are isolated from the substrate electrically due to p-n junction formation. Improvements in the reliability of the AFM lithography technique were achieved by using all-metal tips, which do not wear out as rapidly as metal-coated Si3N4 tips.