Patterned wafer inspection using spatial filtering
AssigneeApplied Materials, Inc.
InventorDaniel I. Some
Life of this patent
Estimating the term…
Abstract
Apparatus for spatial filtering includes a Fourier lens, adapted to collect radiation emitted from a point and to separate the collected radiation into spatial components in a Fourier plane of the lens, and a programmable spatial filter, positioned at the Fourier plane. An image sensor is optically coupled to capture an image of the spatial components of the collected radiation in the Fourier plane, while the components are incident on the filter. A filter controller is coupled to receive and analyze the image captured by the image sensor and, responsive thereto, to control the spatial filter so as to block one or more of the spatial components.
Claims68
Apparatus for optical inspection of a sample, comprising:
- a radiation source, adapted to irradiate a spot on the sample with coherent radiation;
- a Fourier lens, adapted to collect the radiation that is scattered from the spot and to separate the collected radiation into spatial components in a Fourier plane of the lens;
- a programmable spatial filter, positioned at the Fourier plane so as to filter the spatial components of the radiation;
- a detector, positioned to receive the filtered radiation from the spatial filter, and to generate, responsive to the radiation, a signal for processing to detect a characteristic of the sample;
- an image sensor, optically coupled to capture an image of the spatial components of the collected radiation in the Fourier plane, while the components are incident on the filter;
- and
- a filter controller, coupled to receive and analyze the image captured by the image sensor and, responsive thereto, to control the spatial filter so as to determine the spatial components to be received by the detector.
Apparatus for spatial filtering, comprising:
- a Fourier lens, adapted to collect radiation emitted from a point and to separate the collected radiation into spatial components in a Fourier plane of the lens;
- a programmable spatial filter, positioned at the Fourier plane;
- an image sensor, optically coupled to capture an image of the spatial components of the collected radiation in the Fourier plane, while the components are incident on the filter;
- and
- a filter controller, coupled to receive and analyze the image captured by the image sensor and, responsive thereto, to control the spatial filter so as to block one or more of the spatial components.
Optical inspection apparatus, comprising:
- a radiation source, adapted to irradiate a spot on a sample with coherent radiation and to scan the spot along a line on the sample in a scan direction;
- a Fourier lens, adapted to collect the radiation that is scattered from the spot and to direct the collected radiation to a Fourier plane of the lens;
- a programmable spatial filter positioned at the Fourier plane, the spatial filter comprising an array of mirrors that are controllable so that each mirror can be individually tilted;
- about an axis parallel to the scan direction between a first orientation and a second orientation;
- a detector, positioned to receive the collected radiation reflected from the mirrors in the array that are in the first orientation, and not the radiation reflected from the mirrors that are in the second orientation, and to generate, responsive to the radiation, a signal for processing to determine a characteristic of the sample;
- an image sensor, optically coupled to capture an image of spatial components of the collected radiation in the Fourier plane, while the components are incident on the filter;
- and
- a filter controller, coupled to receive and analyze the image captured by the image sensor and, responsive thereto, to control the spatial filter so as to block one or more of the spatial components.
A method for optical inspection of a sample, comprising:
- irradiating a spot on the sample with coherent radiation;
- collecting a portion of the radiation that is scattered from the spot, and separating the collected radiation into spatial components in a Fourier plane;
- positioning a programmable spatial filter in the Fourier plane so as to filter the spatial components of the radiation;
- receiving the filtered radiation from the spatial filter at a detector, and generating, responsive to the filtered radiation, a signal for processing in order to detect a characteristic of the sample;
- capturing on an image sensor an image of the spatial components of the collected radiation in the Fourier plane, while the components are incident on the filter;
- and
- analyzing the image captured by the image sensor and, responsive thereto, controlling the spatial filter so as to determine the spatial components to be received by the detector.
A method according to 38, claim wherein the filter elements comprise shutters, and wherein controlling the spatial filter comprises causing the shutters to move between a first orientation, in which the shutter allows the radiation to pass therethrough toward the detector, and a second orientation, in which the shutter blocks the radiation incident thereon from reaching the detector.
A method for spatial filtering, comprising:
- collecting radiation emitted from a point, and separating the collected radiation into spatial components in a Fourier plane;
- positioning a programmable spatial filter at the Fourier plane;
- capturing an image of the spatial components of the collected radiation in the Fourier plane, while the components are incident on the filter;
- and
- analyzing the captured image and, responsive thereto, controlling the spatial filter so as to block one or more of the spatial components.
A method for optical inspection, comprising:
- irradiating a spot on a sample with coherent radiation, and scanning the spot along a line on the sample in a scan direction;
- collecting a portion of the radiation that is scattered from the spot, and forming a spatial Fourier transform of the collected radiation in a Fourier plane;
- positioning at the Fourier plane a programmable spatial filter comprising an array of mirrors that are controllable so that each mirror can be individually tilted about an axis parallel to the scan direction between a first orientation and a second orientation;
- and
- positioning a detector so as to receive the collected radiation reflected from the mirrors in the array that are in the first orientation, and not the radiation reflected from the mirrors that are in the second orientation, so as to generate, responsive to the radiation, a signal for processing to determine a characteristic of the sample;
- positioning an image sensor so that it is optically coupled to capture an image of spatial components of the collected radiation in the Fourier plane while the components are incident on the filter;
- and
- analyzing the image captured by the image sensor with a filter controller coupled to receive and, in response thereto, control the spatial filter so as to block one or more of the spatial components.
Dependencies are inferred from the claim text.