US5003567A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Soft x-ray reduction camera for submicron lithography
Assignee: Lawrence Livermore National Security LLC
•
Filing: 1989-02-09
•
Granted: 1991-03-26
•
Expires: 2009-02-09
Abstract
Abstract Soft x-ray projection lithography can be performed using x-ray optical components and spherical imaging lenses (mirrors), which form an x-ray reduction camera. The x-ray reduction is capable of projecting a 5x demagnified image of a mask onto a resist coated wafer using 4.5 nm radiation. The diffraction limited resolution of this design is about 135 nm with a depth of field of about 2.8 microns and a field of view of 0.2 cm 2 . X-ray reflecting masks (patterned x-ray multilayer mirrors) which are fabricated on thick substrates and can be made relatively distortion free are used, with a laser produced plasma for the source. Higher resolution and/or larger areas are possible by varying the optic figures of the components and source characteristics.
Inventors
- 👤 Andrew M. Hawryluk
- 👤 Lynn G. Seppala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:05
CPC Classifications
G; G02; G02B; G02B17/00; G02B17/02; G02B17/06; G02B17/0605; G02B17/0621; B; B82; B82Y; B82Y10/00; G03; G03F; G03F7/00; G03F7/20; G03F7/2037; G03F7/2039; G03F7/70; G03F7/70008; G03F7/70033; G03F7/70216; G03F7/70233
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
85 words
Apparatus for performing soft x-ray projection lithography with soft x-rays of a preselected wavelength comprising: a reflecting x-ray mask comprising a substrate and a patterned x-ray multilayer mirror formed on the substrate; substantially normal incidence reflective x-ray imaging means positioned after the mask for projecting an image of the x-ray mask onto an image plane, said imaging means being reflective at the preselected wavelength at substantially normal incidence; wherein the mask substrate is curved to produce a substantially flat field curvature at the image plane.
Claim 2
Dependent Claim
85 words
Apparatus for performing soft x-ray projection lithography with soft x-rays of a preselected wavelength comprising: a reflecting x-ray mask comprising a substrate and a patterned x-ray multilayer mirror formed on the substrate; substantially normal incidence reflective x-ray imaging means positioned after the mask for projecting an image of the x-ray mask onto an image plane, said imaging means being reflective at the preselected wavelength at substantially normal incidence; wherein the mask substrate is curved to produce a substantially flat field curvature at the image plane.
Claim 3
Dependent Claim
72 words
The apparatus of claim 1 wherein the x-ray imaging means comprises: a primary mirror having a multilayer x-ray reflecting convex surface; a secondary mirror having a multilayer x-ray reflecting concave surface; the primary and secondary mirrors being optically aligned in a spaced relationship so that x-rays incident from the mask at substantially normal incidence to the primary mirror are reflected from the primary mirror to the secondary mirror to the image plane.
Claim 4
Dependent Claim
22 words
The apparatus of claim 1 further comprising an x-ray source positioned so that x-rays from the source are incident on the mask.
Claim 5
Dependent Claim
15 words
The apparatus of claim 3 wherein the x-ray source is a layer produced plasma source.
Claim 6
Dependent Claim
32 words
The apparatus of claim 3 further comprising a near normal incidence, reflection condenser means optically aligned with the source and mask to provide substantially uniform illumination of the mask by the source.
Claim 7
Dependent Claim
17 words
The apparatus of claim 1 wherein the mask has a mask contrast of greater than about 100:1.
Claim 8
Dependent Claim
18 words
The apparatus of claim 1 wherein the multilayer mirror is selected from C/Cr, Mo/Si, and B/Ru multilayer mirrors.
Claim 9
Dependent Claim
14 words
The apparatus of claim 2 wherein the primary and secondary mirrors are substantially spherical.
Claim 10
Dependent Claim
14 words
The apparatus of claim 2 wherein the primary and secondary mirrors are substantially aspherical.
Claim 11
Dependent Claim
18 words
The apparatus of claim 1 wherein the imaging means has a demagnification in the range of about 1-10X.
Claim 12
Dependent Claim
23 words
The apparatus of claim 2 wherein the primary and secondary mirrors are coated with a multilayer selected from a Cr/C, Mo/Si, and B/Ru.
Claim 13
Dependent Claim
21 words
The apparatus of claim 3 wherein the source produces x-rays with a wavelength of about 2 nm to about 250 nm.
Claim 14
Dependent Claim
156 words
Apparatus for soft x-ray projection lithography with x-rays of a preselected wavelength in the range of 2 nm to 150 nm, comprising: a reflecting x-ray mask comprising a substrate and a patterned x-ray multilayer mirror formed on the substrate; a substantially spherical primary mirror having a multilayer x-ray reflecting convex surface having a reflectivity at the preselected wavelength at substantially normal incidence; a substantially spherical secondary mirror having a multilayer x-ray reflecting concave surface having a reflectivity at the preselected wave length at substantially normal incidence; the mask, primary mirror and secondary mirror being positioned in a fixed off-axis relationship so that x-rays reflecting by the mask are incident on and reflected by the primary mirror to the secondary mirror and from the secondary mirror to an image plane to project an image of the mask onto the image plane; wherein the mask substrate is curved to produce a substantially flat field at the image plane.
Claim 15
Dependent Claim
156 words
Apparatus for soft x-ray projection lithography with x-rays of a preselected wavelength in the range of 2 nm to 150 nm, comprising: a reflecting x-ray mask comprising a substrate and a patterned x-ray multilayer mirror formed on the substrate; a substantially spherical primary mirror having a multilayer x-ray reflecting convex surface having a reflectivity at the preselected wavelength at substantially normal incidence; a substantially spherical secondary mirror having a multilayer x-ray reflecting concave surface having a reflectivity at the preselected wave length at substantially normal incidence; the mask, primary mirror and secondary mirror being positioned in a fixed off-axis relationship so that x-rays reflecting by the mask are incident on and reflected by the primary mirror to the secondary mirror and from the secondary mirror to an image plane to project an image of the mask onto the image plane; wherein the mask substrate is curved to produce a substantially flat field at the image plane.
Claim 16
Dependent Claim
28 words
The apparatus of claim 13 further comprising a soft x-ray source positioned in a fixed relationship relative to the mask so that x-rays are incident on the mask.
Claim 17
Dependent Claim
17 words
The apparatus of claim 13 wherein the primary and secondary mirrors have a common center of curvature.
Claim 18
Dependent Claim
35 words
The apparatus of claim 15 further comprising a pupil placed in the optical path between the secondary mirror and image plane and in the same plane as the common center of curvature of the mirrors.
Claim 19
Dependent Claim
27 words
The apparatus of claim 15 further comprising condenser means aligned with the source and mask to provide substantially uniform x-ray illumination of the mask by the source.
Claim 20
Dependent Claim
11 words
The apparatus of claim 13 having a demagnification of about 1×10x.
Claim 21
Dependent Claim
28 words
The apparatus of claim 13 wherein the mask, primary mirror and secondary mirror are formed of a plurality of alternating layer pairs selected from carbon/chromium, molybdenum/silicon, and boron/ruthenium.
Claim 22
Dependent Claim
15 words
The apparatus of claim 14 wherein the x-ray source comprises a laser produced plasma source.
Claim 23
Dependent Claim
86 words
Method for performing x-ray projection lithography, comprising: forming an x-ray mask with a substrate and a patterned x-ray multilayer mirror on the substrate; directing a beam of soft x-rays of a preselected wavelength from as source onto the x-ray mask; reflecting the x-rays from the mask; imaging x-rays from the mask onto an image plane by an imaging means having a reflectivity at the preselected wavelength at substantially normal incidence; wherein the mask substrate is curved to produce a substantially flat field at the image plane.
Claim 24
Dependent Claim
86 words
Method for performing x-ray projection lithography, comprising: forming an x-ray mask with a substrate and a patterned x-ray multilayer mirror on the substrate; directing a beam of soft x-rays of a preselected wavelength from as source onto the x-ray mask; reflecting the x-rays from the mask; imaging x-rays from the mask onto an image plane by an imaging means having a reflectivity at the preselected wavelength at substantially normal incidence; wherein the mask substrate is curved to produce a substantially flat field at the image plane.
Claim 25
Dependent Claim
39 words
Method of claim 21 further comprising imaging the x-rays from the mask onto an image plane by reflecting the x-rays from the mask from a substantially spherical primary mirror to a substantially spherical secondary mirror to the image plane.
Claim 26
Dependent Claim
20 words
Method of claim 22 further comprising positioning the primary mirror and secondary mirror to produce an image demagnification of 1-10x.
Claim 27
Dependent Claim
45 words
Method of claim 22 further comprising forming the primary mirror with a multilayer x-ray reflecting convex surface and the secondary mirror with a multilayer x-ray reflecting concave surface, the convex and concave reflecting surfaces having a reflectivity at the preselected wavelength at substantially normal incidence.
Claim 28
Dependent Claim
14 words
Method of claim 21 further comprising producing a substantially uniform illumination of the mask.
Claim 29
Dependent Claim
15 words
A reflection mask, comprising: a curved substrate; a patterned multilayer mirror formed on the substrate.
Claim 30
Dependent Claim
15 words
A reflection mask, comprising: a curved substrate; a patterned multilayer mirror formed on the substrate.
Claim 31
Dependent Claim
38 words
The mask of claim 26 wherein the substrate is curved to produce a substantially flat field curvature at an image plane when the mask is imaged onto the image plane by an imaging means positioned after the mask.
Claim 32
Dependent Claim
17 words
The mask of claim 26 wherein the mask has a mask contrast of greater than about 100:1.
Claim 33
Dependent Claim
18 words
The mask of claim 26 wherein the multilayer mirror is selected from C/Cr, Mo/Si, and B/Ru multilayer mirrors.
Claim 34
Dependent Claim
20 words
The mask of claim 26 wherein the patterned multilayer mirror comprises micron width-lines with a height of about 0.2-0.4 microns.
Claim 35
Dependent Claim
26 words
The mask of claim 26 wherein the patterned multilayer mirror is reflective at a wavelength in the range of about 2 nm to about 250 nm.
Claim 36
Dependent Claim
26 words
The mask of claim 26 wherein the patterned multilayer mirror is reflective at a wavelength in the range of about 4.5 nm to about 13 nm.
Claim 37
Dependent Claim
27 words
The mask of claim 26 wherein the patterned multilayer mirror comprises up to about 200 layer pairs of alternating high refractive index and low refractive index layers.
References Cited (Backward Citations)
JPS5448174A
Cited
US4184078A
Cited
US4411013A
Cited
US4484339A
Cited
EP0066053A1
Cited
US4475223A
Cited
US4572659A
Cited
EP0109193A2
Cited
US4785470A
Cited
US4650983A
Cited
JPS61245160A
Cited
US4737973A
Cited
US4891830A
Cited
EP0252734A2
Cited
JPH01292600A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-03-25 | 1994-09-24 | 1995-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-25 | 1998-09-24 | 1999-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-25 | 2002-09-24 | 2003-03-26 | $7700.00 | Window Closed / Lapsed |