EP0453753A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method and apparatus for enhancing the depth of focus in projection lithography
Assignee: International Business Machines Corp
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Filing: 1991-03-15
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Granted: —
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Expires: 2011-03-15
Abstract
Abstract The invention provides a technique which enables projection lithography to extend to the sub-half micron range by compensating the Depth of Focus (DOF) budget lost in substrate topography with a projection of a non-planar image which is conformal to the substrate (10). The method of achieving a non-planar image field includes the formation of a mask reticle (20) which is a replica of the surface of the semiconductor (10) to be exposed, thus, eliminating substrate topography from the optical DOF budget.
Inventors
- 👤 Mark C. Hakey
- 👤 David V. Horak
- 👤 Peter C. Rath
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 00:19
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70216; G03F7/703; G03F7/20; G03F1/00; G03F1/68; G03F1/70
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
113 words
An image exposure system for projecting a focused image on the surface of a non-planar substrate (10) comprising a projection tool have a predetermined depth of focus, being a function of exposing radiation and Numerical Aperture; a substrate (10) have an exposure surface including an exposure field including at least two regions (12) having a difference in elevation greater than the depth of field of said tool; object image generating means including a plurality of image segments defining a field to be projected, and means for causing a single focused image to be formed within the exposure field on the non-planar surface of said substrate (10) corresponding to the plurality of image segments.
Claim 2
Dependent Claim
38 words
The system of claim 1 wherein the object image generating means comprises a mask reticle (20) having at least one of said plurality of image segments formed on a different plane from the remainder of said image segments.
Claim 3
Dependent Claim
26 words
The system of claim 2 wherein the mask reticle (20) includes a non-planar surface (26) which is substantially similar to the surface of the substrate (10).
Claim 4
Dependent Claim
26 words
The system of claim 2 or 3 wherein the surface (26) of the mask reticle is substantially a replica of the surface of the substrate (10).
Claim 5
Dependent Claim
25 words
The system of claim 1 wherein the image plane formed on the non-planar substrate (10) is substantially conformal with the surface of the substrate (10).
Claim 6
Independent Claim
24 words
The system of one or more of the preceding claims 1 to 5 wherein the exposing radiation is in the range of optical spectra.
Claim 7
Independent Claim
117 words
A method of exposing a composite image on the surface of a non-planar substrate (10) within a single exposure field wherein the substrate (10) includes a plurality of regions (12) of differing height, comprising the steps of: generating a first portion of the image to be exposed from a first plurality of object segments corresponding to a first group of image segments to be projected on to a first of the regions of the substrate (10); and independently generating a second portion of the image to be exposed from a second plurality of object segments corresponding to a second group of image segments to be projected on to a second of the regions of the substrate (10).
Claim 8
Dependent Claim
34 words
The method of claim 7 wherein the steps of generating portions of the images include the use of a mask reticle (20) having at least one non-planar surface (26) within the single exposure field.
Claim 9
Dependent Claim
23 words
The method of claim 8 wherein the surface of the mask reticle (20) is a replica of the surface (10) of the substrate.
Claim 10
Independent Claim
49 words
A method of exposing a semiconductor surface (10) in a series of exposure steps wherein at least one of the masks (20) used to expose at least one of the series of exposure steps is fabricated to include a topographical history of the processing steps which precedes its use.
Claim 11
Dependent Claim
30 words
The method of claim 10 wherein said at least one mask (20) is formed through the use of pattern information present in at least one of its preceding process steps.
References Cited (Backward Citations)
No citation records indexed.
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