Method and apparatus for characterization of a microlithography mask

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.