US4592081A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Adaptive X-ray lithography mask
Assignee: HP Inc
•
Filing: 1984-02-10
•
Granted: 1986-05-27
•
Expires: 2004-02-10
Abstract
Abstract Provided is an apparatus for improving alignment accuracy by distorting in a controlled manner an X-ray lithographic mask to compensate for mask distortions induced primarily by thermally induced clamping effects in E-beam and X-ray exposure systems. A system of additional alignment sensors is used to provide localized misalignment information. This information is then used to provide feedback to a servo system which in turn activates electromechanically translatable clamps which distort the X-ray mask so as to minimize misalignment over the exposure field.
Inventors
- 👤 Steven G. Eaton
- 👤 Graham J. Siddall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:51
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/22; G03F7/00; G03F7/70; G03F7/70691; G03F7/707
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
118 words
A mask aligner for use with a mask and a wafer comprising: clamping means having at least three clamping members for clamping said mask into an X-ray stage and positioning said mask at an initial position; electromechanical means connected to said clamping means for moving said clamping members laterally in the plane of said mask relative to one another and distorting said mask relative to said wafer; sensor means for sensing the distortion of the mask relative to the wafer and for producing a corresponding distortion signal; and feedback means for accepting said corresponding distortion signal and for providing a signal to said electromechanical means so as to reduce in-plane distortion of said mask relative to said wafer.
Claim 2
Dependent Claim
118 words
A mask aligner for use with a mask and a wafer comprising: clamping means having at least three clamping members for clamping said mask into an X-ray stage and positioning said mask at an initial position; electromechanical means connected to said clamping means for moving said clamping members laterally in the plane of said mask relative to one another and distorting said mask relative to said wafer; sensor means for sensing the distortion of the mask relative to the wafer and for producing a corresponding distortion signal; and feedback means for accepting said corresponding distortion signal and for providing a signal to said electromechanical means so as to reduce in-plane distortion of said mask relative to said wafer.
Claim 3
Dependent Claim
107 words
A mask aligner as in claim 1 wherein said sensor means comprises: a first plurality of six alignment patterns on a first surface of said wafer; a second plurality of alignment patterns on said first surface of said wafer; a third plurality of six alignment patterns on a second surface of said mask; and a fourth plurality of alignment patterns on said second surface of said mask, said first and third plurality of six alignment patterns providing isotropic alignment data between said wafer and said mask, respectively, and said second and fourth plurality of alignment patterns providing localized misalignment data between said wafer and said mask respectively.
Claim 4
Dependent Claim
23 words
A mask aligner as in claim 2 wherein said second and fourth plurality of alignment patterns each comprise four or more alignment patterns.
Claim 5
Dependent Claim
28 words
A mask aligner as in claim 1 wherein said electromechanical means comprises: a plurality of flexures each having an actuator, said flexures being connected to said clamping members.
Claim 6
Dependent Claim
100 words
Apparatus for improving mask-to-wafer alignment by reducing in-plane mask distortion, comprising: clamping means for peripheral clamping of a mask in an initial position in generally parallel alignment with a wafer; sensor means for sensing undesired in-plane distortion of the mask relative to the wafer and providing a distortion signal representative thereof; and translation means for moving at least three points on the periphery of said mask laterally in the mask plane and relatively to each other in response to said distortion signal so as to produce a desired in-plane mask distortion relative to said initial position and improve mask-to-wafer alignment.
Claim 7
Dependent Claim
100 words
Apparatus for improving mask-to-wafer alignment by reducing in-plane mask distortion, comprising: clamping means for peripheral clamping of a mask in an initial position in generally parallel alignment with a wafer; sensor means for sensing undesired in-plane distortion of the mask relative to the wafer and providing a distortion signal representative thereof; and translation means for moving at least three points on the periphery of said mask laterally in the mask plane and relatively to each other in response to said distortion signal so as to produce a desired in-plane mask distortion relative to said initial position and improve mask-to-wafer alignment.
Claim 8
Dependent Claim
36 words
Apparatus as defined in claim 5 wherein said clamping means comprises at least three clamping members for peripheral clamping of the mask and said translation means comprises means for individually translating each of said clamping members.
Claim 9
Dependent Claim
39 words
Apparatus as defined in claim 6 wherein said translation means includes a piezoelectric actuator coupled to each of said clamping members and feedback means for providing an actuating signal to each piezoelectric actuator in response to said distortion signal.
Claim 10
Dependent Claim
44 words
Apparatus as defined in claim 7 wherein said sensor means comprises a first plurality of alignment patterns located at different positions on said wafer and a second plurality of alignment patterns on said mask in nominal alignment with said first plurality of alignment patterns.
Claim 11
Independent Claim
100 words
A method for improving mask-to-wafer alignment by reducing in-plane mask distortion, comprising the steps of: clamping a mask at its periphery in an initial position in generally parallel alignment with a wafer; sensing undesired in-plane distortion of the mask relative to the wafer and providing a distortion signal representative of said undesired in-plane distortion; and moving at least three points on the periphery of said mask laterally in the mask plane and relatively to each other in response to said distortion signal so as to produce a desired in-plane mask distortion relative to said initial position and improve mask-to-wafer alignment.
Claim 12
Independent Claim
100 words
A method for improving mask-to-wafer alignment by reducing in-plane mask distortion, comprising the steps of: clamping a mask at its periphery in an initial position in generally parallel alignment with a wafer; sensing undesired in-plane distortion of the mask relative to the wafer and providing a distortion signal representative of said undesired in-plane distortion; and moving at least three points on the periphery of said mask laterally in the mask plane and relatively to each other in response to said distortion signal so as to produce a desired in-plane mask distortion relative to said initial position and improve mask-to-wafer alignment.
Claim 13
Dependent Claim
39 words
The method as defined in claim 9 wherein said step of clamping includes clamping said mask with at least three peripheral clamping members and wherein said step of moving includes individually translating said clamping members relatively to each other.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-05-26 | 1989-11-25 | 1990-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-26 | 1993-11-25 | 1994-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-26 | 1997-11-25 | 1998-05-27 | $7700.00 | Window Closed / Lapsed |