Patent US6765651B1 successfully refreshed from Google Patents.
US6765651B1
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Fast image simulation for photolithography
Assignee: Individual
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Filing: 2003-03-11
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Granted: 2004-07-20
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Expires: 2023-03-11
Abstract
Abstract A fast method simulates photolithography using conventional image processing techniques. Convolution simulates for blurring; erosion and dilation correct for edge diffraction. In one technique, the source image of the photomask is deconvolved to sharpen it and then dilated to remove edge diffraction. The image is eroded, and then convolved according to the resolution of the stepper at the photomask plane. This aerial image can be further eroded to match the effects of resist and developing. Optional thresholding is done to produce a simulated processed wafer image. In a fast technique, the deconvolution step is eliminated. Dilation and erosion are combined into a single erosion. Where a phase shift mask is involved, a complex convolution is used. Source data can come from the photomask electronic design or from a visual image of the actual photomask. Optimizations include: special microprocessor instructions, floating point pixel values, separable convolution and annular illumination simulation.
Inventors
- 👤 Peter J. Fiekowsky
- 👤 Paul R. Kube
- 👤 April Dutta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 03:09
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70491; G03F7/705; G06; G06T; G06T11/00; G06T5/00; G06T5/20; G06T5/30; G06T7/00; G06T7/0002; G06T7/0004; G06T7/001; G06T2207/00; G06T2207/30; G06T2207/30108; G06T2207/30148
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
60 words
A method of producing a simulated aerial image of a wafer, said method comprising: receiving a source image representing a photomask; computing an erosion amount for said source image; performing erosion on said source image by said erosion amount to produce an intermediate image; and performing convolution on said intermediate image to produce said simulated aerial image of said wafer.
Claim 2
Independent Claim
60 words
A method of producing a simulated aerial image of a wafer, said method comprising: receiving a source image representing a photomask; computing an erosion amount for said source image; performing erosion on said source image by said erosion amount to produce an intermediate image; and performing convolution on said intermediate image to produce said simulated aerial image of said wafer.
Claim 3
Dependent Claim
41 words
A method as recited in claim 1 further comprising: performing erosion on said simulated aerial image to produce a simulated wafer resist image, whereby said simulated wafer resist image represents the effects of exposure and development of photoresist on said wafer.
Claim 4
Dependent Claim
43 words
A method as recited in claim 2 further comprising: performing thresholding on said simulated wafer resist image to produce a simulated processed wafer image, whereby said simulated processed wafer image represents the effects of a particular exposure level of photoresist on said wafer.
Claim 5
Dependent Claim
28 words
A method as recited in claim 1 further comprising: resampling said source image to a lower resolution, whereby said method is performed faster as fewer pixels are processed.
Claim 6
Dependent Claim
23 words
A method as recited in claim 4 wherein said lower resolution after resampling is approximately 2-4 pixels per stepper resolution at the mask.
Claim 7
Dependent Claim
17 words
A method as recitcd in claim 1 further comprising: displaying said simulated aerial image to a user.
Claim 8
Dependent Claim
31 words
A method as recited in claim 1 wherein said photomask is a phase shift photomask and wherein said step of performing convolution includes performing a complex convolution using a phase image.
Claim 9
Dependent Claim
23 words
A method as recited in claim 1 further comprising: performing dilation on said intermediate image, whereby effects of edge diffraction are compensated for.
Claim 10
Dependent Claim
25 words
A method as recited in claim 1 wherein said computing an erosion amount takes into account a dilation amount needed to compensate for edge diffraction.
Claim 11
Dependent Claim
17 words
A method as recited in claim 1 wherein said performing erosion includes performing subpixel erosion using blending.
Claim 12
Dependent Claim
24 words
A method as recited in claim 1 wherein said step of performing erosion includes performing subpixel erosion using a zoom-in, integer erode, zoom-out sequence.
Claim 13
Dependent Claim
18 words
A method as recited in claim 1 wherein said step of performing convolution includes performing a separable convolution.
Claim 14
Dependent Claim
28 words
A method as recited in claim 1 further comprising: converting said source image or said intermediate image to floating point pixel values, whereby said method is performed faster.
Claim 15
Independent Claim
59 words
A method of producing a simulated aerial image of a wafer, said method comprising: receiving a source image representing a photomask; performing deconvolution on said source image to produce a deconvolved image; performing erosion on said deconvolved image to produce an intermediate image; and performing convolution on said intermediate image to produce said simulated aerial image of said wafer.
Claim 16
Independent Claim
59 words
A method of producing a simulated aerial image of a wafer, said method comprising: receiving a source image representing a photomask; performing deconvolution on said source image to produce a deconvolved image; performing erosion on said deconvolved image to produce an intermediate image; and performing convolution on said intermediate image to produce said simulated aerial image of said wafer.
Claim 17
Dependent Claim
41 words
A method as recited in claim 14 further comprising: performing erosion on said simulated aerial image to produce a simulated wafer resist image, whereby said simulated wafer resist image represents the effects of exposure and development of photoresist on said wafer.
Claim 18
Dependent Claim
43 words
A method as recited in claim 15 further comprising: performing thresholding on said simulated wafer resist image to produce a simulated processed wafer image, whereby said simulated processed wafer image represents the effects of a particular exposure level of photoresist on said wafer.
Claim 19
Dependent Claim
17 words
A method as recited in claim 14 further comprising: displaying said simulated aerial image to a user.
Claim 20
Dependent Claim
31 words
A method as recited in claim 14 wherein said photomask is a phase shift photomask and wherein said step of performing convolution includes performing a complex convolution using a phase image.
Claim 21
Dependent Claim
23 words
A method as recited in claim 14 further comprising: performing dilation on said intermediate image, whereby effects of edge diffraction are compensated for.
Claim 22
Dependent Claim
17 words
A method as recited in claim 14 wherein said performing erosion includes performing subpixel erosion using blending.
Claim 23
Dependent Claim
22 words
A method as recited in claim 14 wherein said performing erosion includes performing subpixel erosion using a zoom-in, integer erode, zoom-out sequence.
Claim 24
Dependent Claim
18 words
A method as recited in claim 14 wherein said step of performing convolution includes performing a separable convolution.
Claim 25
Dependent Claim
31 words
A method as recited in claim 14 further comprising: converting said source image, said deconvolved image or said intermediate image to floating point pixel values, whereby said method is performed faster.
Claim 26
Independent Claim
67 words
A method of producing a simulated aerial image of a wafer, said method comprising: receiving a source image representing a photomask; calculating an apparent edge displacement due to edge diffraction; performing erosion on said source image using said edge displacement to simulate said apparent edge displacement, thus producing an intermediate image; and performing convolution on said intermediate image to produce said simulated aerial image of said wafer.
Claim 27
Independent Claim
67 words
A method of producing a simulated aerial image of a wafer, said method comprising: receiving a source image representing a photomask; calculating an apparent edge displacement due to edge diffraction; performing erosion on said source image using said edge displacement to simulate said apparent edge displacement, thus producing an intermediate image; and performing convolution on said intermediate image to produce said simulated aerial image of said wafer.
Claim 28
Dependent Claim
17 words
A method as recited in claim 24 wherein said performing erosion includes performing subpixel erosion using blending.
Claim 29
Dependent Claim
22 words
A method as recited in claim 24 wherein said performing erosion includes performing subpixel erosion using a zoom-in, integer erode, zoom-out sequence.
References Cited (Backward Citations)
No citation records indexed.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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