Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Electron beam imaging
Reexamination Certificate
2000-10-18
2003-04-01
Young, Christopher G. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Electron beam imaging
C430S312000, C430S328000, C430S942000
Reexamination Certificate
active
06541182
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the manufacturing of electronic components, and more particularly, to a method and apparatus for forming a finely-patterned resist layer on a substrate surface in the manufacturing of electronic components.
2. Description of the Related Art
In many technology areas, there has been a trend toward miniaturization. In the case of read/write equipment for magnetic storage media, recent technological evolution has increasingly caused a demand to reduce pattern size below 100 nm in order to achieve increased storage densities.
Conventional manufacturing of patterned devices involves patterning a resist layer formed on the surface of a substrate. Since the patterns of resist layers are increasingly required to be more fine than patterns achieved by existing ultraviolet light techniques, new technologies have recently appeared which use electron beams and X-rays. These technologies have shown great potential for forming pattern sizes as small as 100 nm.
However, in view of the continued technological evolution in the field of manufacturing electronic components such as magnetic storage components, it is desired to reduce pattern size drastically below 100 nm. Some new technologies for such nanofabrication, such as SCALPEL (SCattering with Angular Limitation Projection Electron-Beam) and EUV (Extreme Ultraviolet), are promising manufacturing processes within the next decade that achieve 70 nm patterns. See SCALPEL: A Projection Electron-Beam Approach to Sub-Optical Lithography, Technology Review of Lucent Tech. (December 1999).
However, generally, in the pursuit of sub 100 nm patterns, electron beam lithography presently remains one of the best techniques. Of the highest pattern resolutions reported to date, most were achieved using electron beam lithography. Its resolution is capable of defining patterns down to around 20 nm. Thus, e-beam lithography will remain as one of the major sub-100 nm pattern techniques, whether it is used for forming masks for X-ray or other lithography processes, or for direct writing onto resists.
One problem with electron beam lithography, however, is that it is currently impractical for device manufacturing because of long writing times. This issue becomes much more critical when a pattern size is below 30-40 nm because much higher electron beam doses are then needed.
U.S. Pat. No. 5,122,387 to Takenaka et al. describes a hybrid exposure method. In the method of Takenaka et al., an electron beam is used to expose fine pattern portions while UV irradiation is separately used to expose large pattern portions. Because two separate patterns are formed using two separate exposure systems, the fine pattern portions formed by the electron beam exposure still suffer from the above described drawbacks.
BRIEF SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method and apparatus for forming fine exposure patterns that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a method and apparatus that efficiently forms exposure patterns having high resolution.
Another object of the present invention is to provide a method and apparatus for forming exposure patterns that reduce electron beam exposure time.
Another object of the present invention is to provide a method and apparatus for forming resist exposure patterns having high throughput.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure and methods particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a method for forming a pattern in a resist is provided. A resist is formed on a surface of a substrate. A first portion of the resist is exposed to a charged particle beam to alter a first characteristic of the first portion of the resist. A second portion of the resist is exposed to electromagnetic radiation to alter a second characteristic of the second portion of the resist. The second portion is larger than the first portion. At least part of the first portion is removed using the altered characteristics of the resist such that a remaining portion defines the pattern in the resist.
In accordance with a more limited aspect of the invention, the first portion of the resist is exposed to an electron beam.
In accordance with a still more limited aspect of the invention, the second portion of the resist is exposed to ultraviolet light.
In accordance with another aspect of the invention, an apparatus for forming a pattern in a resist on a substrate is provided. An electron-beam unit exposes to an electron beam a representation of a pattern on a first portion of a resist on a substrate. An electromagnetic radiation exposure system exposes a second portion of the resist to electromagnetic radiation. A surface area of the second portion is greater than a surface area of the first portion. A developing unit removes at least part of the first portion of the resist thereby leaving the pattern in the resist.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5122387 (1992-06-01), Takenaka et al.
patent: 6235450 (2001-05-01), Nakasuji
patent: 253808 1 (1996-09-01), None
Bjorkholm et al., “EUV Lithography—The Successor to Optical Lithography?”, Advanced Lithography Department; Technology Journal; 1998, pp.Q1-8 and Lithography pp. 8 and 9.
Krauss et al., “Nano-compact disk with 400 Gbit/in2storage density fabricated using nanoimprint lithography and read with proximal probe”, Nov. 1997, Appl. Phys. Lett. vol. 71, pp. 3174-3176.
New et al., Submicron patterning of thin cobalt films for magnetic storage, J. Vac. Scl. Technol. B, vol. 12, No. 6, pp. 3196-3201 (Nov./Dec. 1994).
Nakatani et al., Ultramicro Fabrications on Fe-Ni Alloys Using Electron-Beam Writing and Reactive-Ion Etching, IEEE Transactions of Magnetics, vol. 32, No. 5, pp. 4448-4451 (Sep. 1996).
White et al., “Patterned Media: A Viable Route to 50 Gbit/in2and Up for Magnetic Recording”, 6 pages, (Manuscript received Jun. 25, 1996).
“SCALPEL: A Projection Electron-Beam Approach to Sub-Optical Lithography”, Technology Review of Lucent Tech. (Dec. 1999).
Chou et al., “Patterned Magnetic Nanostructures and Quantized Magnetic Disks”, Proceedings of the IEEE, vol. 85, No. 4, pp. 652-671 (Apr. 1997).
Suzuki et al., “Research Report on the status of usage of data storage in the U.S.”, Japan Record Media Industry Association, pp. 97-111 (Mar. 1999).
Aoyama Tsutomu
Hatate Hitoshi
Kagotani Tsuneo
Louis Joseph Dogue Isabelle
Morgan & Lewis & Bockius, LLP
TDK Corporation
Young Christopher G.
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