Method and apparatus for determining the position of structure elements of a photolithographic mask

An apparatus for determining a position of at least one structure element of a photolithographic mask, the apparatus comprising:

• a. means for providing a reference image of the at least one structure element of the photolithographic mask, in which the photolithographic mask is configured to be used in a lithography process wherein an exposure apparatus illuminates the photolithographic mask and light passing through the mask or reflected by the mask is projected onto a substrate that is coated with a light-sensitive layer in order to transfer one or more structure elements of the mask onto the light-sensitive coating of the substrate;
• b. means for deriving a data record for the reference image of the at least one structure element of the photolithographic mask, said data record comprising metadata relating to the reference image of the at least one structure element of the photolithographic mask;
• c. means for providing at least one measured image of the at least one structure element of the photolithographic mask, wherein the means for providing the at least one measured image of the at least one structure element of the photolithographic mask comprises means for using at least one alignment marking of the photolithographic mask to align a measurement table onto the photolithographic mask;
• and
• d. means for optimizing the reference image of the at least one structure element of the photolithographic mask and means for correlating the at least one measured image of the at least one structure element of the photolithographic mask and the optimized reference image of the at least one structure element of the photolithographic mask;
• wherein the metadata relate to at least one defect of the reference image of the at least one structure element of the photolithographic mask,
• wherein the at least one defect comprises noise in the reference image of the at least one structure element of the photolithographic mask, and
• wherein optimizing the reference image of the at least one structure element of the photolithographic mask comprises the following:
• reducing the noise in the reference image of the photolithographic mask by replacing the reference image of the photolithographic mask with an averaged reference image of the photolithographic mask of at least two measured reference images of the photolithographic mask.

A position determination apparatus for determining a position of at least one structure element of a photolithographic mask, the position determination apparatus comprising:

• a. a measurement table which is movable in at least two spatial directions and which is embodied to hold the photolithographic mask, in which the photolithographic mask is configured to be used in a lithography process wherein an exposure apparatus illuminates the photolithographic mask and light passing through the mask or reflected by the mask is projected onto a substrate that is coated with a light-sensitive layer in order to transfer one or more structure elements of the mask onto the light-sensitive coating of the substrate;
• b. an optical system comprising an exposure system and a detector which is embodied to record the reference image of the at least one structure element of the photolithographic mask and to record at least one measured image of the at least one structure element of the photolithographic mask, wherein the optical system is further adapted to use at least one alignment marking of the photolithographic mask to align the measurement table onto the photolithographic mask;
• c. an analysis unit which is embodied to analyze the reference image of the at least one structure element of the photolithographic mask for deriving at least one data record which relates to the reference image of the at least one structure element of the photolithographic mask said data record comprising metadata relating to the reference image of the at least one structure element of the photolithographic mask;
• d. an optimization unit which is embodied to optimize the reference image of the at least one structure element of the photolithographic mask with the aid of the derived data record;
• and
• e. a correlation unit which is embodied to carry out a correlation of the optimized reference image of the at least one structure element of the photolithographic mask and the at least one measured image of the at least one structure element of the photolithographic mask,
• wherein the metadata relate to at least one defect of the reference image of the at least one structure element of the photolithographic mask,
• wherein the at least one defect comprises noise in the reference image of the at least one structure element of the photolithographic mask, and
• wherein optimizing the reference image of the at least one structure element of the photolithographic mask comprises the following:
• reducing the noise in the reference image of the photolithographic mask by replacing the reference image of the photolithographic mask with an averaged reference image of the photolithographic mask of at least two measured reference images of the photolithographic mask.

A method for determining a position of at least one structure element of a photolithographic mask, the method comprising the following steps:

• a. providing a reference image of the at least one structure element of the photolithographic mask, in which the photolithographic mask is configured to be used in a lithography process wherein an exposure apparatus illuminates the photolithographic mask and light passing through the mask or reflected by the mask is projected, by using a projection optics system, onto a substrate that is coated with a light-sensitive layer in order to transfer one or more structure elements of the mask onto the light-sensitive coating of the substrate;
• b. deriving a data record for the reference image of the at least one structure element of the photolithographic mask, said data record comprising metadata relating to the reference image of the at least one structure element of the photolithographic mask;
• c. providing at least one measured image of the at least one structure element of the photolithographic mask, wherein providing the at least one measured image of the at least one structure element of the photolithographic mask comprises using at least one alignment marking of the photolithographic mask to align a measurement table onto the photolithographic mask;
• and
• d. optimizing the reference image of the at least one structure element of the photolithographic mask by use of the derived data record and correlating the at least one measured image of the photolithographic mask and the optimized reference image;
• wherein the metadata relate to at least one incorrect setting of the measurement table, which holds the photolithographic mask while recording the reference image of the at least one structure element of the photolithographic mask, in which the at least one incorrect setting of the measurement table comprises at least one of a change in position of the measurement table in the plane of the photolithographic mask in relation to a reference point while recording the reference image or a change in position of the measurement table in the plane perpendicular to the photolithographic mask.

A method for determining a position of at least one structure element of a photolithographic mask, the method comprising the following steps:

• a. providing a reference image of the at least one structure element of the photolithographic mask, in which the photolithographic mask is configured to be used in a lithography process wherein an exposure apparatus illuminates the photolithographic mask and light passing through the mask or reflected by the mask is projected, by using a projection optics system, onto a substrate that is coated with a light-sensitive layer in order to transfer one or more structure elements of the mask onto the light-sensitive coating of the substrate;
• b. deriving a data record for the reference image of the at least one structure element of the photolithographic mask, said data record comprising metadata relating to the reference image of the at least one structure element of the photolithographic mask;
• c. providing at least one measured image of the at least one structure element of the photolithographic mask, wherein providing the at least one measured image of the at least one structure element of the photolithographic mask comprises using at least one alignment marking of the photolithographic mask to align a measurement table onto the photolithographic mask;
• and
• d. optimizing the reference image of the at least one structure element of the photolithographic mask by use of the derived data record and correlating the at least one measured image of the photolithographic mask and the optimized reference image;
• wherein the metadata relate to at least one parameter setting of an optical system of the position determination apparatus, and the at least one parameter setting comprises at least one of a position of a focus when recording the reference image or an exposure time when recording the reference image.