University of California

Maxwell Laboratories, Inc.

Malcolm R Howells

Wenbing Yun

Alastair A MacDowell

Chris Jacobsen

Howard A Padmore

John Spence

A nanomachining method for producing high-aspect ratio precise nanostructures. The method begins by irradiating a wafer with an energetic charged-particle beam. Next, a layer of patterning material is deposited on one side of the wafer and a layer of etch stop or metal plating base is coated on the other side of the wafer. A desired pattern is generated in the patterning material on the top surface of the irradiated wafer using conventional electron-beam lithography techniques. Lastly, the wafer is placed in an appropriate chemical solution that produces a directional etch of the wafer only in the area from which the resist has been removed by the patterning process. The high mechanical strength of the wafer materials compared to the organic resists used in conventional lithography techniques with allows the transfer of the precise patterns into structures with aspect ratios much larger than those previously achievable.

Method for nanomachining high aspect ratio structures

A non-contact X-ray projection lithography method for producing a desired X-ray image on a selected surface of an X-ray-sensitive material, such as photoresist material on a wafer, the desired X-ray image having image minimum linewidths as small as 0.063 .mu.m, or even smaller. A hologram and its position are determined that will produce the desired image on the selected surface when the hologram is irradiated with X-rays from a suitably monochromatic X-ray source of a selected wavelength .lambda.. On-axis X-ray transmission through, or off-axis X-ray reflection from, a hologram may be used here, with very different requirements for monochromaticity, flux and brightness of the X-ray source. For reasonable penetration of photoresist materials by X-rays produced by the X-ray source, the wavelength X, is preferably chosen to be no more than 13.5 nm in one embodiment and more preferably is chosen in the range 1-5 nm in the other embodiment. A lower limit on linewidth is set by the linewidth of available microstructure writing devices, such as an electron beam.

X-ray lithography using holographic images

A polished aspheric mirror focusses a fan X-ray beam from a point source onto a work piece as a straight image line. The work piece can be efficiently exposed to the X-ray beam by simply tilting the aspheric mirror about a rotational axis, causing the focused image line to sweep across the workpiece. The aspheric mirror is designed to collimate the beam in one direction, e.g., the horizontal direction, and focus the beam in the other direction, e.g., the vertical direction, thereby creating the focused image line at the workpiece. This process is achieved by representing the mirror surface as at least a fourth order Maclaurin series polynomial, and by adjusting the coefficients of such Maclaurin series to create and maintain the desired straight image line. The mirror surface is then polished using computer controlled polishing techniques to realize the designed shape.

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Berkeley, CA, United States of America

Malcolm R Howells