摘要:
A detector detects radiation from a mask to form an image, but the focal plane of the image is in front of the mask. Any particles arranged on the mask will be in focus. However, the pattern on the mask will be out of focus. It is therefore possible to detect the existence and location of particles on a mask having an arbitrary pattern. The depth of field of the detector is small and the focal plane is no further from the surface of the patterning device than two times the depth of field.
摘要:
A detector detects radiation from a mask to form an image, but the focal plane of the image is in front of the mask. Any particles arranged on the mask will be in focus. However, the pattern on the mask will be out of focus. It is therefore possible to detect the existence and location of particles on a mask having an arbitrary pattern. The depth of field of the detector is small and the focal plane is no further from the surface of the patterning device than two times the depth of field.
摘要:
Methods and systems for inspection of an object include the use of spectroscopic techniques for the detection of unwanted particles on an object's surface, based on the different responses of the unwanted particles as compared with the object to be inspected due to their different materials. Time resolved spectroscopy and/or energy resolved spectroscopy of secondary photon emission from the surface of the object can be used to obtain Raman and photoluminescence spectra. The objects to be inspected can for example be a patterning device as used in a lithographic process, for example a reticle, in which case the presence of metal, metal oxide or organic particles can be detected, for example. The methods and apparatus are highly sensitive, for example, being able to detect small particles (sub 100 nm, particularly sub 50 nm) on the patterned side of an EUV reticle.
摘要:
In an aspect, an inspection method for detecting the presence or absence of a defect on an object, the object comprising a recess having a physical depth, is disclosed. The method includes directing radiation at the object, the radiation having a wavelength that is substantially equal to twice an optical depth of the recess, detecting radiation that is re-directed by the object or a defect on the object, and determining the presence or absence of a defect from the re-directed radiation.
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.
摘要:
A system for removing contaminant particles from the path of the beam of EUV radiation is provided in which at least a first AC voltage is provided to a pair of electrodes on opposite sides of the path of the beam of EUV radiation as a first stage of a regime of voltages and, as a second stage of the regime of voltages, a DC voltage is provided to the electrodes.
摘要:
A contaminant trap is used in an EUV radiation source apparatus. An EUV radiation beam is generated and focused through a low pressure gaseous atmosphere into a virtual source point. The EUV radiation creates a plasma in the low pressure hydrogen atmosphere through which it passes. A contaminant trap including electrodes is located in or around radiation beam as it approaches the virtual source point. A DC biasing source is connected to the electrodes to create an electric field oriented to deflect out of the beam path contaminant particles that have been negatively charged by the plasma. Additional RF electrodes and/or an ionizer enhance the plasma to increase the charging of the particles. The deflecting electrodes can be operated with RF bias for a short time, to ensure dissipation of the enhanced plasma.
摘要:
Methods and systems for inspection of an object include the use of spectroscopic techniques for the detection of unwanted particles on an object's surface, based on the different responses of the unwanted particles as compared with the object to be inspected due to their different materials. Time resolved spectroscopy and/or energy resolved spectroscopy of secondary photon emission from the surface of the object can be used to obtain Raman and photoluminescence spectra. The objects to be inspected can for example be a patterning device as used in a lithographic process, for example a reticle, in which case the presence of metal, metal oxide or organic particles can be detected, for example. The methods and apparatus are highly sensitive, for example, being able to detect small particles (sub 100 nm, particularly sub 50 nm) on the patterned side of an EUV reticle.
摘要:
A lithographic patterning device deformation monitoring apparatus (38) comprising a radiation source (40), an imaging device (42), and a processor (50). The radiation source being configured to direct a plurality of beams of radiation (41) with a predetermined diameter towards a lithographic patterning device (MA) such that they are reflected by the patterning device. The imaging detector configured to detect spatial positions of the radiation beams (41′) after they have been reflected by the patterning device. The processor configured to monitor the spatial positions of the radiation beams and thereby determine the presence of a patterning device deformation. The imaging detector has an collection angle which is smaller than a minimum angle of diffraction of the radiation beams.
摘要:
An article such as an EUV lithography reticle is inspected to detect contaminant particles. The method comprises applying a fluorescent dye material to the article, illuminating the article with radiation at wavelengths suitable for exciting the fluorescent dye, monitoring the article for emission of second radiation by the fluorescent dye at a wavelength different from the first radiation, and generating a signal representing contamination in the event of detecting the second radiation. In one example, measures such as low-affinity coatings may be applied to the reticle to reduce affinity for the dye molecules, while the dye molecules will bind by physical or chemical adsorption to the contaminant particles. Dyes may be selected to have fluorescence behavior enhanced by hydrophobicity or hydrophilicity, and contaminant surfaces treated by buffer coatings accordingly.