# US 2013/0156939 A1 · Method and apparatus for analyzing and/or repairing of an euv mask defect

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- Number: US 2013/0156939 A1
- Document ID: US20130156939A1
- Status: Published application
- Kind: A1
- Application number: 13/805,960
- Filed: 2011-06-24
- Published: 2013-06-20
- Earliest claimed: 2010-06-23
- Assignees: Carl Zeiss SMS GmbH; Carl Zeiss SMT GmbH
- Inventors: Michael Budach; Tristan Bret; Klaus Edinger; Thorsten Hofmann; Heiko Feldmann; Johannes Ruoff
- Web page: https://patentgrep.com/patent/US20130156939A1

## CPC

- G01N 21/95: characterised by the material or shape of the object to be examined (G01N21/89 - G01N21/91, G01N21/94 take precedence)
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 40/00: Manufacture or treatment of nanostructures
- C23C 14/48: Ion implantation
- G03B 27/68: Introducing or correcting distortion, e.g. in connection with oblique projection
- G03F 1/24: Reflection masks; Preparation thereof
- G03F 1/72: Repair or correction of mask defects
- G03F 1/74: by charged particle beam [CPB], e.g. focused ion beam
- G03F 1/84: Inspecting
- G03F 7/705: {Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions}
- G03F 7/7065: {Defects, e.g. optical inspection of patterned layer for defects}
- G06F 30/20: Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30)
- G06T 7/0002: {Inspection of images, e.g. flaw detection}
- G21K 5/00: Irradiation devices (discharge tubes for irradiating H01J37/00)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- 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)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G21K: HANDLING OF PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES

## Abstract

The invention relates to a method for analyzing a defect of a photolithographic mask for an extreme ultraviolet (EUV) wavelength range (EUV mask) comprising the steps of: (a) generating at least one focus stack relating to the defect using an EUV mask inspection tool, (b) determining a surface configuration of the EUV mask at a position of the defect, (c) providing model structures having the determined surface configuration which have different phase errors and generating the respective focus stacks, and (d) determining a three dimensional error structure of the EUV mask defect by comparing the at least one generated focus stack of the defect and the generated focus stacks of the model structures.

## Claims

### Claim 1

A method for analyzing a defect of a photolithographic mask for an extreme ultraviolet (EUV) wavelength range (EUV mask), the method comprising:
a. generating at least one focus stack relating to the defect using an EUV mask inspection tool;
b. determining a surface configuration of the EUV mask at a position of the defect;
c. providing model structures having the determined surface configuration which have different phase errors and generating the respective focus stacks; and
d. determining a three dimensional error structure of the EUV mask defect by comparing the at least one generated focus stack of the defect and the generated focus stacks of the model structures.

### Claim 2 (depends on 1)

The method of claim 1, further comprising applying different repairing methods to the three dimensional error structure and simulating respective focus stacks in order to determine an optimal repairing method.

### Claim 3 (depends on 2)

The method of claim 2, further comprising applying the optimal repairing method to the defective position.

### Claim 4 (depends on 1)

The method of claim 1, wherein the model structures comprise an absorbing pattern structure on a surface of the EUV mask.

### Claim 5 (depends on 4)

The method of claim 4, further comprising providing the absorbing pattern structure from EUV mask design data and/or from a recording of at least one image.

### Claim 6 (depends on 1)

The method of claim 1, further comprising using a repairing method correcting the three dimensional error structure, so that a resulting multilayer structure is at least approximately corrected to an ideal multilayer structure.

### Claim 7 (depends on 6)

The method of claim 6, further comprising applying the repairing method directly onto the defective position of the EUV mask.

### Claim 8 (depends on 2)

The method of claim 2, wherein the repairing method comprises at least partially removing the multilayer structure, in particular drilling at least one hole into the multilayer structure.

### Claim 9 (depends on 2)

The method of claim 2, wherein the repairing method comprises locally compacting and/or expanding the multilayer structure and/or a substrate of the EUV mask by locally focusing femtosecond laser pulses into the EUV mask.

### Claim 10

An inspection microscope for photolithographic masks in the extreme ultraviolet wavelength range adapted to perform any of the methods of the preceding claims.

### Claim 11

A method for reducing a buried defect in an extreme ultraviolet (EUV) optical element, the method comprising:
directing an ion beam onto the buried defect so that an ion dose is implanted in the EUV optical element suitable to locally change a volume of the EUV optical element.

### Claim 12 (depends on 11)

The method of claim 11, wherein the ion beam comprises inert gas ions, preferably noble gas ions, and most preferably helium ions.

### Claim 13 (depends on 11)

The method of claim 11, further comprising adapting an ion beam energy to a depth of the buried defect below a surface of the EUV optical element.

### Claim 14 (depends on 13)

The method of claim 13, wherein the ion beam energy comprises a range of 1 keV to 200 keV, preferably 5 keV to 100 keV, and most preferably of 10 keV to 50 keV.

### Claim 15 (depends on 13)

The method of claims 13, wherein the EUV optical element comprises a multilayer structure and wherein the energy of the ion beam is selected such that the ions are essentially implanted below layers of the multilayer structure of the EUV optical element.

### Claim 16 (depends on 11)

The method of claim 11, wherein the EUV optical element further comprises at least one capture layer arranged between a substrate and a multilayer structure, and wherein the ion beam energy is adjusted so that the ions are essentially implanted in the at least one capture layer.

### Claim 17 (depends on 11)

The method of claim 11, further comprising arranging a local protection layer on a surface of the EUV optical element through which the ion beam is directed when repairing the buried defect prior to directing the ion beam onto the buried defect and removing the local protection layer at the end of the repairing.

### Claim 18 (depends on 11)

The method of claim 11, wherein the ion beam is not perpendicularly directed through a surface of the EUV optical element onto the buried defect.

### Claim 19 (depends on 11)

The method of claim 11, wherein the buried defect is a concave defect, in particular a pit and/or a scratch and the local volume change comprises a local volume increase, in particular a local height increase.

### Claim 20 (depends on 11)

The method of claim 11, wherein the buried defect is a convex defect, in particular a bump and the local volume change comprises a local volume decrease, in particular a local height decrease.

### Claim 21 (depends on 1, 11)

The method of claim 11, further comprising analysing the buried defect with the method of claim 1.

### Claim 22 (depends on 11)

A focused ion beam apparatus for performing the method of claim 11.