Methods and apparatus for inspection of articles, EUV lithography reticles, lithography apparatus and method of manufacturing devices

摘要

An EUV lithography reticle is inspected to detect contaminant particles. The inspection apparatus comprises illumination optics with primary radiation. An imaging optical system with plural branches is arranged to form and detect a plurality of images, each branch having an image sensor and forming its image with a different portion of radiation received from the illuminated article. A processor combines information from the detected images to report on the presence and location of contaminant particles. In one or more branches the primary radiation is filtered out, so that the detected image is formed using only secondary radiation emitted by contaminant material in response to the primary radiation. In a dark field imaging branch using the scattered primary radiation, a spatial filter blocks spatial frequency components associated with periodic features of the article under inspection, to allow detection of particles which cannot be detected by secondary radiation.

主权项

1. A method comprising:
directing primary radiation at one or more first wavelengths, from a radiation source, to interact with an article to produce secondary radiation, the secondary radiation being produced from the primary radiation interacting with non-fluorescent material of a contaminant particle on the article, the secondary radiation having one or more second wavelengths different than the one or more first wavelengths; forming an image, with detection optics, of the article based on filtering out, using a filter, the primary radiation and transmitting, using the filter, the secondary radiation; and detecting the image with an image sensor.