Semiconductor device manufacturing: process – Chemical etching – Combined with the removal of material by nonchemical means
Reexamination Certificate
2000-07-18
2002-11-19
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Chemical etching
Combined with the removal of material by nonchemical means
C438S945000, C425S385000, C264S293000
Reexamination Certificate
active
06482742
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to imprint lithography and, in particular, to imprint lithography wherein direct fluid pressure is used to press a mold into a thin film. The process is particularly useful to provide nanoimprint lithography of enhanced resolution and uniformity over an increased area.
BACKGROUND OF THE INVENTION
Lithography is a key process in the fabrication of semiconductor integrated circuits and many optical, magnetic and micromechanical devices. Lithography creates a pattern on a thin film carried on a substrate so that, in subsequent process steps, the pattern can be replicated in the substrate or in another material which is added onto the substrate.
Conventional lithography typically involves applying a thin film of resist to a substrate, exposing the resist to a desired pattern of radiation, and developing the exposed film to produce a physical pattern. In this approach, resolution is limited by the wavelength of the radiation, and the equipment becomes increasingly expensive as the feature size becomes smaller.
Nanoimprint lithography, based on a fundamentally different principle offers high resolution, high throughput, low cost and the potential of large area coverage. In nanoimprint lithography, a mold with nanoscale features is pressed into a thin film, deforming the shape of the film according to the features of the mold and forming a relief pattern in the film. After the mold is removed, the thin film can be processed to remove the reduced thickness portions. This removal exposes the underlying substrate for further processing. Details of nanoimprint lithography are described in applicant's U.S. Pat. No. 5,772,905 issued Jun. 30, 1998 and entitled “Nanoimprint Lithography”. The '905 patent is incorporated herein by reference.
The usual method of pressing the mold into the thin film involves positioning the mold and the substrate on respective rigid plates of a high precision mechanical press. With such apparatus, the process can generate sub-25 nm features with a high degree of uniformity over areas on the order of 12 in
2
. Larger areas of uniformity would be highly advantageous to increase throughput and for many applications such as displays.
SUMMARY OF THE INVENTION
An improved method of imprint lithography involves using direct fluid pressure to press a mold into a substrate-supported film. Advantageously the mold and/or substrate are sufficiently flexible to provide wide area contact under the fluid pressure. Fluid pressing can be accomplished by sealing the mold against the film and disposing the resulting assembly in a pressurized chamber. It can also be accomplished by subjecting the mold to jets of pressurized fluid. The result of this fluid pressing is enhanced resolution and high uniformity over an enlarged area.
REFERENCES:
patent: 4325779 (1982-04-01), Rossetti
patent: 4731155 (1988-03-01), Napoli et al.
patent: 5234756 (1993-08-01), Kohama et al.
patent: 5958326 (1999-09-01), Caferro
patent: 6159400 (2000-12-01), Laquer
patent: 6190929 (2001-02-01), Wang et al.
Lowenstein & Sandler PC
Niebling John F.
Simkovic Viktor
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