H. H. Gilgen

Deep‐ultraviolet induced wet etching of GaAs

We report on deep‐ultraviolet (UV), light‐assisted wet etching of GaAs. The etching chemistry differs from that using visible wavelengths and all doping types of GaAs can be efficiently etched. The UV processing offers rapid etching at low, nonthermal laser intensities and permits very deep, vertical features to be made.

Direct writing of metal conductors with near-uv light

Deposition of micrometer-scale tungsten, molybdenum and platinum lines with the aid of the uv light from an argon-ion laser was investigated. Tungsten and molybdenum were deposited from their corresponding carbonyls and platinum from an acetylacetonate compound. High-quality metal conductors could be achieved for tungsten and platinum using a combined photolytic and pyrolytic, or “hybrid”, deposition scheme. The resistivity for these two deposited metals was approximately twice the bulk value. For molybdenum the deposition process was fast and dominated by the pyrolysis; the corresponding line resistivity was slightly higher than for the two other metals.

Waveguiding effects in laser‐induced aqueous etching of semiconductors

The rapid, ultraviolet‐induced aqueous etching produces vertical, high‐aspect features in GaAs samples of different crystal orientations. Much of the speed and anisotropy of the etching is attributed to the formation of efficient hollow, optical waveguides. These guides have been characterized by measuring the optical loss and the field distribution within the guide. The optical loss is typically small and does not restrict the etching of deep features.

Maskless chemical etching of submicrometer gratings in single‐crystalline GaAs

Submicrometer optical gratings are produced in a GaAs surface by a laser‐enhanced, wet‐etching process which permits the fabrication of different grating profiles. The etch process was investigated by in situ optical measurements of the diffracted beams and electron microscopy.

Photodeposition rates of metal from metal alkyls

Laser photodeposition of zinc from diethylzinc is experimentally studied. Parametric studies of laser power, intensity, gas pressure, and temperature are evaluated to characterize the deposition process. The results of these experiments verify the trends predicted by a simple theoretical treatment. The investigated deposition process shows contributions from both gas‐phase molecules and adsorbed molecular layers. The ability to control the relative contribution from these two media is demonstrated.

Interaction of deep-ultraviolet laser light with GaAs surfaces in aqueous solutions

We have investigated the surface oxidation of GaAs and subsequent oxide dissolution that is caused by ultraviolet laser light at 257 nm in an aqueous environment. This process has a chemistry distinct from the related process that uses visible light. Further, unique light-guided surface-relief structures result from the ultraviolet chemistry and the ultraviolet optical properties of the semiconductor surface.

Ultraviolet-light-enhanced oxidation of gallium arsenide surfaces studied by X-ray photoelectron and auger electron spectroscopy

Abstract Laser-enhanced oxidation of gallium arsenide surfaces has been investigated. The oxidation was performed either in air or in pure water at room temperature. Light at ultraviolet wavelengths was found to enhance the oxidation rate much more strongly than at visible wavelengths. The oxidation in air leaves the surface almost stoichiometric, whereas the treatment in pure water results in a gallium-rich surface.

Maskless laser writing of silicon dioxide

A laser direct writing technique for forming insulating layers of silicon dioxide from an organosilicate film on various substrate materials is shown. The process resolution is a function of the thermal properties of the substrate and is shown to be 1 μm. The technique allows for a local variation in the oxide thickness by changing process parameters. The quality of the laser written layers is compared to similar films formed by conventional organosilicate processing.

The Physics of Ultraviolet Photodeposition

Ultraviolet photodeposition is a technique for direct laser writing of submicrometer metal patterns on solid substrates. The process involves a wealth of unexplored physical phenomena including micrometer-scale ultraviolet photochemistry and surface and interface chemical dynamics. This paper briefly reviews the current developments in understanding the process physics. In addition, the applications of the technique to microelectronics fabrication are briefly discussed.

High Resolution Etching of Gaas and Cds Crystals

Submicrometer gratings have been etched in GaAs and CdS crystals which have been immersed in an oxidizing etch and illuminated with interferring laser beams. A resolution of 170 nm was obtained. At high laser intensity and with prolonged etching time the surface properties of the material are degraded. The use of in-situ optical measurements of grating parameters allows ready optimization of the grating fabrication process.