| 摘要 |
A mask inspection system for inspecting a reflective mask using electromagnetic radiation with a working wavelength lambda from the extreme ultraviolet region (EUV), comprises a microscope system (MIC) for magnifying imaging of an object arranged in an object plane (OP) of the microscope system in an image plane which is optically conjugate to the object plane; a mask holding device which is configured to hold the mask in such a way that a mask surface (MS) to be examined is arranged in the region of the object plane (OP) of the microscope system; an illumination system (ILL) for receiving radiation from an EUV radiation source and for generating illumination radiation (ILR), which impinges on the mask surface (MS) in a measurement field (MF); a sensor device with a sensor surface (SS), which is arranged in the image plane (IP) of the microscope system or in a plane optically conjugate to the image plane, and an evaluation device (EV) connected to the sensor device. In order to carry out a scanning operation, the mask is moved parallel to the object plane and parallel to a scanning plane in such a way that regions of the mask surface adjoining one another in the scanning direction can successively be moved into the measurement field and the evaluation device is configured for integrating signals, captured in a spatially resolved fashion on the sensor surface, in-phase to the movement of the mask. The mask inspection system is characterized by a compensation device (KOMP) for actively compensating deformations in the mask surface, induced in the region of the measurement field (MF) by the illumination radiation (ILR), for reducing surface gradients in the region of the measurement field compared to a mask surface in absence of the compensation. |
