I stripped most of the "stock stuff" from this posting and tried to keep it just to the interesting facts on a subject. It does me proud to see how clean this thread has become as a repository of decent information. I use it as the one place I can come to keep a historcal record of lithogrpahy information that I want archived.
The abstract and other items below clearly indicates to me that the owner of this patent has to be dealt with by
every manufacturer of step and scans in the industry for the next 8 years at least. Ultratech Stepper (UTEK) may have bought this patent about 2.5 years ago, and could have some reprecussions down the road.
United States Patent 5,281,996 - This appears to be a patent for Step and Scan Technology as We know it today.
United States Patent 5,281,996
Bruning , et al. January 25, 1994
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PHOTOLITHOGRAPHIC REDUCTION IMAGING OF EXTENDED FIELD
Abstract
A mask or reticle for a single large microcircuit device is imaged in portions by an axially centered
photolithographic reduction lens having a movable mask stage in addition to a movable wafer stage so that the
portions of the complete device are imaged in juxtaposed registry on the wafer. This allows a single microcircuit
device larger than the image field of the reduction lens to be imaged in a scanning mode or in a succession of steps forming images at the desired resolution range of 0.1-0.50 um.
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Inventors: Bruning; John H. (Pittsford, NY); Beaulieu; David R. (Fairport, NY)
Assignee: General Signal Corporation (Stamford, CT)
Appl. No.: 940537
Filed: September 4, 1992
Current U.S. Class: 355/77; 355/53
Intern'l Class: G03B 027/42; G03B 027/32
Field of Search: 355/53,77
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References Cited [Referenced By]
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U.S. Patent Documents
4864360 Sep., 1989 Isohata et al. 355/53.
4869998 Sep., 1989 Eccles et al. 430/311.
4878086 Oct., 1989 Isohata et al. 355/77.
4924257 May., 1990 Jain 355/53.
4933714 Jun., 1990 Buckley et al. 355/43.
5160957 Nov., 1992 Ina et al. 355/43.
Other References
"Optical Imaging for Microfabrication", by J. H. Bruning, J. Vac. Sci. Technol., 17(5), Sep./Oct. 1980, pp.
1147-1155.
"Stepand Scan: A Systems Overview of a New Lithography Tool", by J. D. Buckley and C. Karatzas, SPIE vol.
1088, Optical/Laser Micro lithography II (1989), pp. 424-433.
Primary Examiner: Wintercorn; Richard A.
Attorney, Agent or Firm: Eugene Stephens & Associates
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Claims
We claim:
1. A method of imaging a large microcircuit device in a resolution range of 0.1-0.50 micrometers, said method
comprising:
a. using an axially centered photolithographic reduction lens having a circular image field with a diameter that is less than a diagonal of said microcircuit device;
b. arranging a stage for a mask for said microcircuit device to be movable relative to said lens;
c. arranging a stage for a wafer on which said microcircuit device is imaged to be movable relative to said lens;
d. controlling the accuracy of movement of said stages relative to said lens; and
e. using said movement of said stages to correlate different regions of said mask moved into a field of view of said lens with correspondingly different regions of said wafer moved into said image field of said lens in a pattern that successively images the entire area of said microcircuit device.
2. The method of claim 1 including adjusting a focal distance between said lens and said different regions of said wafer.
3. The method of claim 1 wherein said imaging of said microcircuit device occurs during said movements of said
mask and wafer stages, and a diametrically extending region of said circular image field is used for said imaging.
4. The method of claim 1 wherein said movement of said stages is stopped while a portion of said microcircuit
device is imaged, and successively imaged portions of said microcircuit device are registered along boundaries of said imaged portions on said wafer.
5. The method of claim 4 including determining image quality of said microcircuit device by inspecting
predetermined areas of said device, including an area along said boundaries.
6. The method of claim 4 including separating said different regions of said mask at said field of view and joining
said correspondingly different regions of said wafer at said image field.
7. The method of claim 4 including using a plurality of said masks for said microcircuit device and moving said
masks successively into said field of view of said lens.
8. A method of imaging a microcircuit device having a total size larger than the image field of an axially centered photolithographic reduction lens used for imaging said microcircuit device, said method comprising:
a. separately imaging each of a plurality of portions of a mask for said microcircuit device by moving said mask
relative to a viewing field of said lens and moving a wafer into a corresponding succession of positions in said
image field of said lens; and
b. controlling said lens and the movements of said mask and said wafer so that separately projected and reduced images of said mask portions are formed in registered juxtaposition on said wafer.
9. The method of claim 8 including dividing and separating said portions of said mask at said field of view and
interconnecting in said registered juxtaposition corresponding image portions formed on said wafer.
10. The method of claim 8 including using separate reticles for said portions of said mask.
11. The method of claim 8 including varying the focus of said images formed on different areas of said wafer.
12. The method of claim 8 including determining the quality of the imaging of said microcircuit device on said wafer by inspecting a predetermined region of said microcircuit device along said registered juxtaposition.
13. A method of imaging a large microcircuit device with an axially centered photolithographic reduction lens
having an image field smaller than said device, said method comprising:
a. positioning a mask for said device movably within the object side field of view of said lens;
b. positioning a wafer movably within an axial image field of said lens so that a reduction of said mask can be
imaged on said wafer; and
c. imaging a portion of said mask on a region of said wafer and moving said mask and said wafer to change the
portion of said mask being imaged and the region of said wafer on which images are formed in juxtaposed registry with each other until all of said mask is imaged on said wafer.
14. The method of claim 13 including dividing said mask into portions and separately imaging said mask portions onto said wafer in said juxtaposed registry.
15. The method of claim 14 including separating said mask portions at said field of view of said lens and joining on said wafer the juxtaposed images of said portions.
16. The method of claim 14 including using separate reticles for said portions of said mask.
17. The method of claim 14 including stopping the imaging during movement of said mask and said wafer.
18. The method of claim 13 including forming the images on said wafer during movement of said mask and said
wafer.
19. The method of claim 13 including controlling said lens and the movements of said wafer and said mask relative to said lens so that a resolution range of images formed on said wafer is 0.1-0.50 micrometers.
20. The method of claim 13 including varying a focal distance between said lens and said wafer for different image regions of said wafer.
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Description
FIELD OF THE INVENTION
This invention involves photolithographic reduction imaging such as used in imaging microcircuit devices.
BACKGROUND
Equipment for forming photolithographic reduction images of microcircuit devices is under heavy pressure to
improve or reduce the resolution dimension of elements in the imaged device while also imaging larger devices
having bigger overall dimensions and containing ever-increasing numbers of finely resolved elements. The optical challenge of producing a microlithographic reduction lens that is free enough of aberration and distortion to meet the desired resolution range of 0.1-0.50 .mu.m is already formidable; and to add the requirement that the microcircuit device become even larger compounds the difficulty of solving all the optical problems.
We have devised a solution that can use the best available photolithographic reduction lenses, without increasing the size of the axial image field of such lenses, to image microcircuit devices larger than will fit within a single image field. This allows well-understood and reliable lens systems, as they have evolved for present day "steppers," to be used in a different way that forms fine resolution images of microcircuit devices larger than such lenses can image in a single exposure. Our invention advances the capability of the best axially centered, photolithographic reduction lenses so that they can image microcircuit devices in extended fields that were not previously possible.
July 12, 2001 - Ultratech Stepper, Inc. introduced its new Jupiter 157 Mid-Field lithography stepper. Ultratech's
new Jupiter tool supports the development and early production of high-end devices requiring 100 nm and below
processes, on all wafer sizes up to 300 mm. This new system, available in first quarter 2002, combines its 300 mm wafer handling capability with a 4 mm x 4 mm field size, 0.40 - 0.75 variable numerical aperture (NA) lens,
world-class overlay ability and high system reliability to address the process challenges associated with 157 nm lithography.
This is brought to you as a courtesy of Radarview, the Financial newsletter specifically geared towards
the semiconductor, networking, and telecom sectors of the market.
Andrew Vance
www.radarview.com
avance@radarview.com
BTW - just to keep everything on the up and up, the following is the link to where we downloaded the patent, for
those that want the "whole enchilada."
164.195.100.11.
Of course it could be easier to just to go to uspto.gov and do a search for the patent number. |
