# US 9,478,395 B1 · Alignment and registration targets for multiple-column charged particle beam lithography and inspection

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- Number: US 9,478,395 B1
- Document ID: US9478395B1
- Status: Granted
- Kind: B1
- Application number: 14/523,909
- Filed: 2014-10-26
- Granted: 2016-10-25
- Earliest claimed: 2013-11-27
- Assignees: Multibeam Corporation
- Applicants: Multibeam Corporation
- Inventors: Kevin M. Monahan; Michael C. Smayling; Theodore A. Prescop; David K. Lam
- Web page: https://patentgrep.com/patent/US9478395B1

## CPC

- H01J 37/3045: {Object or beam position registration}
- G03F 1/42: Alignment or registration features, e.g. alignment marks on the mask substrates
- G03F 1/86: by charged particle beam [CPB]
- G03F 9/7076: {Mark details, e.g. phase grating mark, temporary mark}
- G03F 9/7084: {Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels}
- H01J 37/222: {Image processing arrangements associated with the tube}
- H01J 37/261: {Details}
- H01J 37/265: {Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination}
- H01J 37/3005: {Observing the objects or the point of impact on the object}
- H01J 37/3177: {Multi-beam, e.g. fly's eye, comb probe}
- H01J 2237/063: Electron sources
- H01J 2237/2611: Stereoscopic measurements and/or imaging
- H01J 2237/2826: Calibration
- H01J 2237/30444: Calibration grids
- H01J 2237/31762: Computer and memory organisation
- H01J 2237/31764: Dividing into sub-patterns
- H01J 2237/31774: Multi-beam
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)

## Abstract

The present application discloses methods, systems and devices for using charged particle beam tools to pattern and inspect a substrate. The inventors have discovered that it is highly advantageous to use patterns generated using the Hadamard transform as alignment and registration marks (Hadamard targets) for multiple-column charged particle beam lithography and inspection tools. Further, superior substrate alignment and layer-to-layer pattern registration accuracy can be achieved using Hadamard targets patterned in edge-proximal portions of the substrate that are typically stripped bare of resist prior to lithography, in addition to Hadamard targets patterned in inner substrate portions. High-order Hadamard targets can also be patterned and imaged to obtain superior column performance metrics for applications such as super-rapid beam calibration DOE, column matching, and column performance tracking. Superior alignment and registration, and column parameter optimization, allow significant yield gains.

## Claims

### Claim 1

A method of substrate lithography and/or inspection using charged particle beam columns, comprising the actions of:
a) writing multiple edge block pattern-based Hadamard targets and multiple inner block pattern-based Hadamard targets onto the substrate using multiple first charged particle beams;
b) first imaging said edge and inner Hadamard targets using said first beams;
c) adding a resist layer to the substrate such that imaging said inner Hadamard targets is prevented and imaging said edge Hadamard targets is enabled;
d) second imaging said edge Hadamard targets using multiple second charged particle beams;
e) mapping location data of said edge Hadamard targets from said second imaging to said inner Hadamard targets in dependence on location data of said edge and inner Hadamard targets from said first imaging;
f) calculating offsets for columns corresponding to said edge and inner Hadamard targets in at least partial dependence on said first and second imaging location data and said mapped location data; and
g) writing and/or imaging multiple cut features on the substrate using said second beams, said features being targeted in at least partial dependence on said offsets,
wherein individual ones of said beams are projected by individual ones of the columns, and different ones of the columns have different writing areas.

### Claim 2 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein, in step a), said first beams write at least one edge and/or inner Hadamard target in the writing area of each column projecting said second beams.

### Claim 3 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein said first beams are produced by the same EBI and/or EBL tool, and/or by the same array of columns, and/or by the same columns, as said second beams.

### Claim 4 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein, when preparing the substrate for step a), edge-bead removal is minimized, and wherein said edge Hadamard targets are written on a portion of the substrate that is substantially bare of resist when writing subsequent pattern layers.

### Claim 5 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein the substrate is moved from one stage to a different stage between step b) and step d).

### Claim 6 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein different ones of said beams perform said writing and/or said imaging differently and simultaneously.

### Claim 7 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein said offsets are calculated also in at least partial dependence on the design layout database and the position of the stage.

### Claim 8 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein said cut features comprise line-cuts and holes.

### Claim 9 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein said first beams write cut features to the substrate in addition to said edge and inner Hadamard targets.

### Claim 10 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein said imaging said Hadamard targets comprises initial-imaging expected locations of center and/or most-symmetric blocks of said Hadamard targets at least sufficiently to determine which portions of said Hadamard targets were imaged, calculating actual locations of said blocks in at least partial dependence on said initial-imaging, and refined-imaging at said actual locations.

### Claim 11 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein at least some of said Hadamard targets are high-order Hadamard targets.

### Claim 12 (depends on 11)

The method of substrate lithography and/or inspection of claim 11, wherein said imaging cut features comprises inspecting said cut features for defects using said second beams, classifying possible defects in said cut features in at least partial dependence on said inspecting, optimizing beam parameters of said second beams for highest resolution using said high-order Hadamard targets, re-imaging possible killer defects using said highest resolution, and classifying said possible defects in at least partial dependence on said re-imaging.

### Claim 13 (depends on 1)

The method of substrate lithography and/or inspection of claim 1, wherein two or more of the blocks in at least one of said Hadamard targets are transposed within said Hadamard target.

### Claim 14 (depends on 13)

The method of substrate lithography and/or inspection of claim 13, wherein said Hadamard targets comprising transposed blocks are used to identify, track, and/or authenticate the individual substrate-derived product unit to which they are written.

### Claim 15

A method of substrate lithography and/or inspection using multiple charged particle beam columns, comprising the actions of:
a) writing multiple edge targets and multiple inner targets onto the substrate using multiple first charged particle beams;
b) first imaging said edge and inner targets using respective ones of said first beams;
c) adding a resist layer to the substrate such that non-resist-coated imaging said inner targets is prevented and imaging said edge targets is enabled;
d) second imaging said edge targets using multiple second charged particle beams;
e) mapping location data of said edge targets from said second imaging to said inner targets in dependence on location data of said edge and inner targets from said first imaging;
f) calculating offsets for columns corresponding to said edge and inner targets in at least partial dependence on said first and second imaging location data and said mapped location data; and
g) writing and/or imaging multiple cut features on the substrate using said second beams, said features being targeted in at least partial dependence on said offsets,
wherein individual ones of said beams are projected by individual ones of the columns, and different ones of the columns have different writing areas.

### Claim 16 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein, in step a), said first beams write at least one edge and/or inner target in the writing area of each column projecting said second beams.

### Claim 17 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein said first beams are produced by the same EBI and/or EBL tool, and/or by the same array of columns, and/or by the same columns, as said second beams.

### Claim 18 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein, when preparing the substrate for step a), edge-bead removal is minimized, and wherein said edge targets are written on a portion of the substrate that is substantially bare of resist when writing subsequent pattern layers.

### Claim 19 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein the substrate is moved from one stage to a different stage between step b) and step d).

### Claim 20 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein different ones of said beams perform said writing and/or said imaging differently and simultaneously.

### Claim 21 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein said offsets are calculated also in at least partial dependence on the design layout database and the position of the stage.

### Claim 22 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein said cut features comprise line-cuts and holes.

### Claim 23 (depends on 15)

The method of substrate lithography and/or inspection of claim 15, wherein said first beams write cut features to the substrate in addition to said edge and inner targets.

### Claim 24

A substrate lithography and inspection tool, comprising:
a substrate stage;
multiple charged particle beam columns, individual ones of said columns configured to produce an individual charged particle beam, different ones of said columns having different writing areas; and
one or more column controllers storing instructions in a computer-readable non-transitory medium that, when executed, direct said beam controllers to:
control said columns to write multiple edge Hadamard targets and multiple inner Hadamard targets in multiple writing areas on the substrate;
control said columns to first image said edge and inner Hadamard targets;
control said columns to second image said edge Hadamard targets in at least partial dependence on image data from said first image action; and
map location data of said edge Hadamard targets from said second image action to said inner Hadamard targets in dependence on location data of said edge and inner Hadamard targets from said first image action;
calculate offsets for columns corresponding to said edge and inner Hadamard targets in at least partial dependence on image data from said first image action and said second image action and said mapped location data; and
control said columns to write and/or image multiple cut features on the substrate, said features being targeted in at least partial dependence on said offsets.

### Claim 25 (depends on 24)

The substrate lithography and inspection tool of claim 24, wherein said column controllers are configured to control said columns to write at least one edge and/or inner Hadamard target in the writing area of each column performing said write and/or image multiple cut features action.

### Claim 26 (depends on 24)

The substrate lithography and inspection tool of claim 24, wherein said column controllers are configured to control said columns to write said edge Hadamard targets on a portion of the substrate that is substantially bare of resist when writing subsequent pattern layers.

### Claim 27 (depends on 24)

The substrate lithography and inspection tool of claim 24, further comprising a resist-adder, configured to add resist layers to the substrate such that either writing edge and inner Hadamard targets is enabled, or imaging edge Hadamard targets is enabled and imaging inner Hadamard targets is prevented, by different ones of said layers.

### Claim 28 (depends on 24)

The substrate lithography and inspection tool of claim 24, wherein said column controllers are configured to control different ones of said columns to perform said write actions and said image actions differently and simultaneously.

### Claim 29 (depends on 24)

The substrate lithography and inspection tool of claim 24, wherein said column controllers are configured to calculate said offsets also in at least partial dependence on the design layout database and the position of the stage.

### Claim 30 (depends on 24)

The substrate lithography and inspection tool of claim 24, wherein said cut features comprise line-cuts and holes.

### Claim 31 (depends on 24)

The substrate lithography and inspection tool of claim 24, wherein said image Hadamard targets action comprises initial-imaging expected locations of center and/or most-symmetric blocks of said Hadamard targets at least sufficiently to determine which portions of said Hadamard targets were imaged, calculating actual locations of said blocks in at least partial dependence on said initial-imaging, and refined-imaging at said actual locations.

### Claim 32 (depends on 24)

The substrate lithography and inspection tool of claim 24, wherein at least some of said Hadamard targets are high-order Hadamard targets.

### Claim 33 (depends on 32)

The substrate lithography and inspection tool of claim 32, wherein said column controllers are configured such that said image cut features action comprises inspecting said cut features for defects using said columns, classifying possible defects in said cut features in at least partial dependence on said inspecting, optimizing beam parameters of said columns for highest resolution using said high-order Hadamard targets, re-imaging possible killer defects using said highest resolution, and classifying said possible defects in at least partial dependence on said re-imaging.

### Claim 34

A substrate lithography and inspection tool, comprising:
a substrate stage;
multiple charged particle beam columns, individual ones of said columns configured to produce an individual charged particle beam, different ones of said columns having different writing areas; and
one or more column controllers storing instructions in a computer-readable non-transitory medium that, when executed, direct said beam controllers to:
control said columns to write multiple edge targets and multiple inner targets in multiple writing areas on the substrate;
control said columns to first image said edge and inner targets;
control said columns to second image said edge targets, when non-resist-coated imaging of said inner targets is prevented, in at least partial dependence on image data from said first image action;
map location data of said edge targets from said second image action to said inner targets in dependence on location data of said edge and inner targets from said first image action;
calculate offsets for columns corresponding to said edge and inner targets in at least partial dependence on image data from said first image action and said second image action and said mapped location data; and
control said columns to write and/or image multiple cut features on the substrate said features being targeted in at least partial dependence on said offsets.

### Claim 35 (depends on 34)

The substrate lithography and inspection tool of claim 34, wherein said column controllers are configured to control said columns to write at least one edge and/or inner target in the writing area of each column performing said write and/or image multiple cut features action.

### Claim 36 (depends on 34)

The substrate lithography and inspection tool of claim 34, wherein said column controllers are configured to control said columns to write said edge targets on a portion of the substrate that is substantially bare of resist when writing subsequent pattern layers.

### Claim 37 (depends on 34)

The substrate lithography and inspection tool of claim 34, further comprising a resist-adder, configured to add resist layers to the substrate such that either writing edge and inner targets is enabled, or imaging edge targets is enabled and imaging inner targets is prevented, by different ones of said layers.

### Claim 38 (depends on 34)

The substrate lithography and inspection tool of claim 34, wherein said column controllers are configured to control different ones of said columns to perform said write actions and said image actions differently and simultaneously.

### Claim 39 (depends on 34)

The substrate lithography and inspection tool of claim 34, wherein said column controllers are configured to calculate said offsets also in at least partial dependence on the design layout database and the position of the stage.

### Claim 40 (depends on 34)

The substrate lithography and inspection tool of claim 34, wherein said cut features comprise line-cuts and holes.