Abstract: A beam homogenizer for homogenizing a beam of radiation and an illumination system and metrology apparatus comprising such a beam homogenizer as provided. The beam homogenizer comprises a filter system having a controllable radial absorption profile and configured to output a filtered beam and an optical mixing element configured to homogenize the filtered beam. The filter system may be configured to homogenize the angular beam profile radially and said optical mixing element may be configured to homogenize the angular beam profile azimuthally.

Abstract: An inspection apparatus including: a substrate holder configured to hold a substrate; an aperture device; and an optical system configured to direct a first measurement beam of radiation onto the substrate, the first measurement beam having a first intensity distribution, and configured to direct a second focusing beam of radiation onto the substrate at a same time as the first measurement beam is directed on the substrate, the second focusing beam having a second intensity distribution, wherein at least part of the second intensity distribution is spatially separated from the first intensity distribution at least at the substrate and/or the aperture device.

Abstract: An inspection apparatus includes an optical system, which has a radiation beam delivery system for delivering radiation to a target, and a radiation beam collection system for collecting radiation after scattering from the target. Both the delivery system and the collection system comprise optical components that control the characteristics of the radiation and the collected radiation. By controlling the characteristics of one or both of the radiation and collected radiation, the depth of focus of the optical system may be increased.

Abstract: Disclosed is a metrology apparatus for measuring a parameter of a lithographic process, and associated computer program and method. The metrology apparatus comprises an optical system for measuring a target on a substrate by illuminating the target with measurement radiation and detecting the measurement radiation scattered by the target; and an array of lenses. Each lens of the array is operable to focus the scattered measurement radiation onto a sensor, said array of lenses thereby forming an image on the sensor which comprises a plurality of sub-images, each sub-image being formed by a corresponding lens of the array of lenses. The resulting plenoptic image comprises image plane information from the sub-images, wavefront distortion information (from the relative positions of the sub-images) and pupil information from the relative intensities of the sub-images.

Abstract: A metrology target formed by a lithographic process on a substrate includes a plurality of component gratings. Images of the target are formed using +1 and ?1 orders of radiation diffracted by the component gratings. Regions of interest (ROIs) in the detected image are identified corresponding the component gratings. Intensity values within each ROI are processed and compared between images, to obtain a measurement of asymmetry and hence overlay error. Separation zones are formed between the component gratings and design so as to provide dark regions in the image. In an embodiment, the ROIs are selected with their boundaries falling within the image regions corresponding to the separation zones. By this measure, the asymmetry measurement is made more tolerant of variations in the position of the ROI. The dark regions also assist in recognition of the target in the images.

Abstract: A metrology target formed by a lithographic process on a substrate includes a plurality of component gratings. Images of the target are formed using +1 and ?1 orders of radiation diffracted by the component gratings. Regions of interest (ROIs) in the detected image are identified corresponding the component gratings. Intensity values within each ROI are processed and compared between images, to obtain a measurement of asymmetry and hence overlay error. Separation zones are formed between the component gratings and design so as to provide dark regions in the image. In an embodiment, the ROIs are selected with their boundaries falling within the image regions corresponding to the separation zones. By this measure, the asymmetry measurement is made more tolerant of variations in the position of the ROI. The dark regions also assist in recognition of the target in the images.

Abstract: An approach is used to estimate and correct the overlay variation as function of offset for each measurement. A target formed on a substrate includes periodic gratings. The substrate is illuminated with a circular spot on the substrate with a size larger than each grating. Radiation scattered by each grating is detected in a dark-field scatterometer to obtain measurement signals. The measurement signals are used to calculate overlay. The dependence (slope) of the overlay as a function of position in the illumination spot is determined. An estimated value of the overlay at a nominal position such as the illumination spot's center can be calculated, correcting for variation in the overlay as a function of the target's position in the illumination spot. This compensates for the effect of the position error in the wafer stage movement, and the resulting non-centered position of the target in the illumination spot.

Abstract: A metrology target formed by a lithographic process on a substrate includes a plurality of component gratings. Images of the target are formed using +1 and ?1 orders of radiation diffracted by the component gratings. Regions of interest (ROIs) in the detected image are identified corresponding the component gratings. Intensity values within each ROI are processed and compared between images, to obtain a measurement of asymmetry and hence overlay error. Separation zones are formed between the component gratings and design so as to provide dark regions in the image. In an embodiment, the ROIs are selected with their boundaries falling within the image regions corresponding to the separation zones. By this measure, the asymmetry measurement is made more tolerant of variations in the position of the ROI. The dark regions also assist in recognition of the target in the images.

Abstract: A scatterometer configured to derive a property of a substrate, includes an optical arrangement that produces a beam of radiation. An objective lens is arranged to focus the beam of radiation onto a target on the substrate. The optical arrangement is arranged to change the divergence of the beam incident on the objective lens, thereby changing spherical aberration caused by the objective lens on the beam focused on the target. A detection arrangement is arranged to detect the beam of radiation after reflection or scattering from the substrate.

Abstract: A metrology apparatus is arranged to illuminate a plurality of targets with an off-axis illumination mode. Images of the targets are obtained using only one first order diffracted beam. Where the target is a composite grating, overlay measurements can be obtained from the intensities of the images of the different gratings. Overlay measurements can be corrected for errors caused by variations in the position of the gratings in an image field.

Abstract: A metrology apparatus is arranged to illuminate a plurality of targets with an off-axis illumination mode. Images of the targets are obtained using only one first order diffracted beam. Where the target is a composite grating, overlay measurements can be obtained from the intensities of the images of the different gratings. Overlay measurements can be corrected for errors caused by variations in the position of the gratings in an image field.

Abstract: A scatterometer configured to derive a property of a substrate, includes an optical arrangement that produces a beam of radiation. An objective lens is arranged to focus the beam of radiation onto a target on the substrate. The optical arrangement is arranged to change the divergence of the beam incident on the objective lens, thereby changing spherical aberration caused by the objective lens on the beam focused on the target. A detection arrangement is arranged to detect the beam of radiation after reflection or scattering from the substrate.

Abstract: An illumination profile useable in a lithographic apparatus to match the output of a target lithographic apparatus is obtained by obtaining a reference CD vs. pitch function for the lithographic projection apparatus at at least a plurality of pitch values using a reference illumination profile; obtaining a target CD vs. pitch function at at least the plurality of pitch values; generating a CD sensitivity map for the lithographic projection apparatus for a given pattern; calculating from the reference CD vs. pitch function, the target CD vs. pitch function and the CD sensitivity map, a suitable illumination profile to be used in said lithographic apparatus to expose said given pattern.

Abstract: The method involves selecting features of a pattern to be imaged, notionally dividing the source into a plurality of source elements, for each source element, calculating the process window for each selected feature and then the OPC rules that optimize the overlap of the calculated process windows. Finally, those source elements are selected for which the overlapping of the process windows and the OPC rules satisfy specified criteria. The selected source elements define the source intensity distribution.

Abstract: In a lithographic apparatus the angle dependence of the intensity distribution of a projection beam at a substrate is controlled. A beam splitter is located in the beam near a pupil plane. The beam splitter splits off an auxiliary beam, which is used to measure information about the spatial intensity distribution of the beam at the pupil plane. The measured position dependence in the auxiliary beam may be decontrolled using boundary conditions inherent to the illuminator to compensate for offset between the pupil plane and a detection element. The measured position dependence may be used to control parameters of an optical element that manipulates the position dependence in the pupil plane. An example of such an optical element is a matrix of elements that controllably steer the direction of parts of the beam. Thus a continuous feedback loop may be realized.

Abstract: A lithographic projection apparatus includes, a radiation source for providing a projection beam of radiation, a support structure for supporting a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern, a substrate table for holding a substrate, a projection system for projecting the patterned beam onto a target portion of the substrate, the radiation source further includes, an illumination system for conditioning the beam of radiation so as to provide a conditioned radiation beam so as to be able to illuminate the patterning device; the illumination system defining a plane of entrance wherein the radiation beam enters the illumination system, and a beam delivery system comprising redirecting elements for redirecting and delivering the projection beam from a radiation source to the illumination system.

Abstract: The method involves selecting features of a pattern to be imaged, notionally dividing the source into a plurality of source elements, for each source element, calculating the process window for each selected feature and then the OPC rules that optimize the overlap of the calculated process windows. Finally, those source elements are selected for which the overlapping of the process windows and the OPC rules satisfy specified criteria. The selected source elements define the source intensity distribution.

Abstract: In a lithographic apparatus the angle dependence of the intensity distribution of a projection beam at a substrate is controlled. A beam splitter is located in the beam near a pupil plane. The beam splitter splits off an auxiliary beam, which is used to measure information about the spatial intensity distribution of the beam at the pupil plane. The measured position dependence in the auxiliary beam may be deconvoluted using boundary conditions inherent to the illuminator to compensate for offset between the pupil plane and a detection element. The measured position dependence may be used to control parameters of an optical element that manipulates the position dependence in the pupil plane. An example of such an optical element is a matrix of elements that controllably steer the direction of parts of the beam. Thus a continuous feedback loop may be realized.