Method and apparatus for characterization of a microlithography mask

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.

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.

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.

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.