Granted Patent B2

US 12,693,594 · App. 18/385,114 · Granted Jul 28, 2026

Inventors: Ulrich Matejka (Jena, DE); Sascha Perlitz (Jena, DE); Markus Deguenther (Florstadt, DE)

Assignee: Carl Zeiss SMT GmbH

G03F1/84G01N21/8806G01N21/956G01N2021/8835G01N2021/95676G03F1/72

Abstract

Claims (54)

1 . A method of characterizing a microlithography mask,

wherein the mask to be characterized is illuminated with light from a light source via an illumination optics unit, said light having a wavelength of less than 30 nm; and

wherein light that passes in a used beam path from the light source via the mask to a sensor unit is evaluated;

wherein, at least intermittently, a portion of the light emitted by the light source is outcoupled from the used beam path by use of a mirror array having a multitude of independently adjustable mirror elements; and

wherein, intermittently by use of the mirror array, all light is outcoupled from the used beam path for establishment of a defined illumination time of the sensor unit;

wherein, in an intermittent manner, the settings of the mirror elements are chosen such that a first group of mirror elements is in an illumination beam path leading from the light source to the mask, and a second group of mirror elements is in an imaging beam path leading from the mask to the sensor unit.

2 . The method of claim 1 , wherein the outcoupled light is directed at least partly to a beam trap.

3 . The method of claim 1 , wherein, at least intermittently, the intensity of a light component outcoupled from the used beam path by the mirror array is detected with an intensity sensor.

4 . A method of characterizing a microlithography mask,

wherein the mask to be characterized is illuminated with light from a light source via an illumination optics unit, said light having a wavelength of less than 30 nm; and

wherein light that passes in a used beam path from the light source via the mask to a sensor unit is evaluated;

wherein, at least intermittently, a portion of the light emitted by the light source is outcoupled from the used beam path by use of a mirror array having a multitude of independently adjustable mirror elements; and

wherein, at least intermittently, the intensity of a light component outcoupled from the used beam path by the mirror array is detected with an intensity sensor that is different from the sensor unit.

5 . The method of claim 4 , wherein greyscale adjustment is achieved by actuating at least some of the mirror elements in such a way that they outcouple light from the used beam path only for some of the period of illumination of the sensor unit.

6 . A method of characterizing a microlithography mask,

wherein the mask to be characterized is illuminated with light from a light source via an illumination optics unit, said light having a wavelength of less than 30 nm; and

wherein light that passes in a used beam path from the light source via the mask to a sensor unit is evaluated;

wherein, at least intermittently, a portion of the light emitted by the light source is outcoupled from the used beam path by use of a mirror array having a multitude of independently adjustable mirror elements; and

wherein greyscale adjustment is achieved by actuating at least some of the mirror elements in such a way that they outcouple light from the used beam path only for some of the period of illumination of the sensor unit;

wherein, in an intermittent manner, the settings of the mirror elements are chosen such that a first group of mirror elements is in an illumination beam path leading from the light source to the mask, and a second group of mirror elements is in an imaging beam path leading from the mask to the sensor unit.

7 . The method of claim 6 , wherein, in an intermittent manner, the settings of the mirror elements are chosen such that light hits the mask at an angle of at least 85° based on the mask surface.

8 . The method of claim 6 , wherein the light from the light source has a wavelength of less than 15 nm.

9 . An apparatus for characterizing a microlithography mask, comprising

a light source for generating light of a wavelength of less than 30 nm;

an illumination optics unit for illuminating the mask to be characterized with light from the light source;

a sensor unit;

an evaluation unit for evaluating the light that passes in a used beam path from the light source via the mask to the sensor unit;

a mirror array composed of a multitude of independently adjustable mirror elements via which at least a portion of the light can be outcoupled from the used beam path; and

an actuating unit for actuating the mirror array;

wherein use of this actuation for establishment of a defined illumination time of the sensor unit, it is possible to intermittently outcouple all light from the used beam path by use of the mirror array;

wherein the actuating unit is configured such that, in an intermittent manner, the settings of the mirror elements are chosen such that a first group of mirror elements is in an illumination beam path leading from the light source to the mask, and a second group of mirror elements is in an imaging beam path leading from the mask to the sensor unit.

10 . The apparatus of claim 9 , comprising a beam trap for receiving a light component outcoupled from the used beam path by the mirror array.

11 . The apparatus of claim 9 , comprising an intensity sensor for detecting the intensity of a light component outcoupled from the used beam path by the mirror array.

12 . An apparatus for characterizing a microlithography mask, comprising

a light source for generating light of a wavelength of less than 30 nm;

an illumination optics unit for illuminating the mask to be characterized with light from the light source;

a sensor unit;

an evaluation unit for evaluating the light that passes in a used beam path from the light source via the mask to the sensor unit;

a mirror array composed of a multitude of independently adjustable mirror elements via which at least a portion of the light can be outcoupled from the used beam path; and

an intensity sensor for detecting the intensity of a light component outcoupled from the used beam path by the mirror array, wherein the intensity sensor is different from the sensor unit.

13 . The apparatus of claim 9 , wherein the light from the light source has a wavelength of less than 15 nm.

14 . The apparatus of claim 9 , wherein the apparatus is configured to implement a method comprising:

illuminating the mask to be characterized with the light from the light source via the illumination optics unit;

evaluating light that passes in the used beam path from the light source via the mask to the sensor unit;

outcoupling, at least intermittently, a portion of the light emitted by the light source from the used beam path by use of the mirror array; and

coupling, intermittently by use of the mirror array, all light from the used beam path for establishment of a defined illumination time of the sensor unit.

15 . The apparatus of claim 14 , comprising a beam trap configured to receive at least a portion of the outcoupled light.

16 . The apparatus according of claim 12 wherein the apparatus is configured to implement a method comprising:

illuminating the mask to be characterized with the light from the light source via the illumination optics unit;

evaluating light that passes in the used beam path from the light source via the mask to the sensor unit;

outcoupling, at least intermittently, a portion of the light emitted by the light source from the used beam path by use of the mirror array; and

coupling, intermittently by use of the mirror array, all light from the used beam path for establishment of a defined illumination time of the sensor unit.

17 . The apparatus of claim 16 , comprising a beam trap configured to receive at least a portion of the outcoupled light.

18 . The method of claim 1 wherein greyscale adjustment is achieved by actuating at least some of the mirror elements in such a way that they outcouple light from the used beam path only for some of the period of illumination of the sensor unit.

Assignments (3)

Priority Claims (1)

Continuity (2)

References Cited (46)