Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Patent
1996-07-18
2000-07-25
Nuzzolillo, Maria
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
430396, 430942, 430966, 430967, 430325, G03C 500
Patent
active
060935200
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention pertains to microscopic machines, structures, and devices, particularly to microscopic machines, structures, and devices having a high aspect ratio, and to methods of making such machines, structures, and devices.
BACKGROUND ART
Microscopic machines, structures, devices, and integrated circuits (hereafter collectively called "microstructures" for simplicity) have wide application. Integrated circuits are used in devices too numerous to be recited. Microstructures other than integrated circuits, whose dimensions are typically on the order of several hundred microns down to one micron, or even into the submicron range, also have a wide range of applications. They have been used in micromechanics, microoptics, integrated optics, sensors, actuators, and chemical engineering. Microstructures that have been built include such structures as gears, nozzles, chromatographic columns, acceleration sensors, microturbines, micromotors, and linear actuators.
Microstructures are usually manufactured through a lithography process. In lithography, one or more "masks" are initially prepared, each mask incorporating all or part of the pattern to be formed on a sample surface. Transparent and opaque areas of the mask represent the desired pattern. Radiation, such as visible light, ultraviolet light, x-rays, an electron beam, or an ion beam, is transmitted through the mask onto a resist. After exposure, the resist (which may have either a positive tone or a negative tone) is developed to form the pattern on the sample surface.
To support the opaque portions of the pattern in the mask, a substrate or carrier is used that is reasonably transparent to radiation at the wavelength used for the exposure. For lithography in visible or ultraviolet wavelengths, glass has typically been used as the carrier. For x-ray masks, carriers have typically been expensive membranes a few microns thick, usually made of a low-Z ("Z"=atomic number) material such as silicon, beryllium, titanium, aluminum, silicon nitride, or graphite.
In making an integrated circuit, it is usually desirable to have the "depth" of a feature (i.e., the dimension in the direction normal to the surface of the pattern) be relatively small. By contrast, in making microstructures other than integrated circuits, it is often desirable to have the "depth" of the feature be relatively large (i.e., deep-etch lithography), to impart a three-dimensional structure to the microstructure, or a reasonable degree of strength to the microstructure, or both.
The resolution of a microstructure is the dimension, in a direction parallel to the structure's surface, of the smallest reproducible feature, or the smallest reproducible gap between adjacent features. The "aspect ratio" of a microstructure is the ratio of the depth of a feature to the resolution. To the inventors' knowledge, an aspect ratio of about 50 is the highest aspect ratio that has previously actually been achieved for any microstructure having a resolution of 10 microns or smaller.
Three methods of imaging have previously been used in lithography. In proximity imaging, the mask is positioned a small but finite distance (or gap) from the sample surface. Proximity imaging is predominantly used in x-ray lithography.
In projection imaging, a projection lens is placed between the mask and the sample to focus light onto the sample surface. (Alternatively, a condenser lens may be placed before the mask.) Projection imaging is predominantly used in visible and ultraviolet optical lithography.
In contact (or zero-gap) printing, the mask is placed directly on (but not adhered to) the sample surface. Contact printing is rarely used in lithography. In x-ray lithography, contact printing can result in serious contamination problems for the sample, and in degraded integrity for the mask. In optical lithography, contact printing can result in deterioration of the image from uncontrolled multiple reflections and light interferences between the mask and the sample surface.
Producing masks for lithographic
REFERENCES:
patent: 4165395 (1979-08-01), Chang
patent: 5334467 (1994-08-01), Cronin et al.
patent: 5468595 (1995-11-01), Livesay
patent: 5512395 (1996-04-01), Rostoker et al.
patent: 5554484 (1996-09-01), Rostoker et al.
patent: 5591564 (1997-01-01), Rostoker et al.
patent: 5624791 (1997-04-01), Kawabata et al.
Liu, H. I., et al., "Self-limiting Oxidation for Fabricating sub-5 nm Silicon Nanowires," Appl. Phys. Lett. (USA), vol. 64, pp. 1383-1385 (1994) (abstract) only.
"LIGA--Movable Microstructures," Kernforschungszentrum Karslruhe (1993?).
J. Mohr et al., "Herstellung von beweglichen Mikrostrukturen mit dem LIGA-Verfahren," KfK Nachrichten, Jahrgang 23, 2-3/91, pp. 110-117 (1991) (not in english).
E. Spiller et al., "X-Ray Lithography," Research Report, I.B.M. T.J. Watson Research Center (1977).
Saile Volker
Vladimirsky Olga
Vladimirsky Yuli
Board of Supervisors of Louisiana State University and Agricultu
Nuzzolillo Maria
Runnels John H.
Weiner Laura
LandOfFree
High aspect ratio microstructures and methods for manufacturing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High aspect ratio microstructures and methods for manufacturing , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High aspect ratio microstructures and methods for manufacturing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1335334