Abstract:
A method of determining the position of an alignment mark on a substrate, the alignment mark having first and second segment, the method including illuminating the alignment mark with radiation, detecting radiation diffracted by the alignment mark and generating a resulting alignment signal. The alignment signal has a first component received during illumination of the first segment only, a second component received during illumination of the second segment only, and a third component received during simultaneous illumination of both segments. The positions of the segments are determined using the first component, the second component and the third component of the alignment signal.
Abstract:
A target structure such as an alignment mark on a semiconductor substrate becomes obscured by an opaque layer so that it cannot be located by an alignment sensor. A position for the mark is determined using an edge position sensor and relative position information that defines the position of the mark relative to one or more edge portions of the substrate is stored prior to formation of the opaque layer. A window can be opened in the opaque layer, based on the determined position. After revealing the target structure, the alignment sensor can, if desired, measure more accurately the position of the target structure, for use in controlling a further lithographic step. The edge position sensor may be a camera having an angle-selective behavior. The edge position sensor may be integrated within the alignment sensor hardware.
Abstract:
A method for determining one or more optimized values of an operational parameter of a sensor system configured to measure a property of a substrate is disclosed. The method includes: determining a quality parameter for a plurality of substrates; determining measurement parameter values for the plurality of substrates using the sensor system for a plurality of values of the operational parameter; comparing a substrate to substrate variation of the quality parameter and a substrate to substrate variation of a mapping of the measurement parameter values; and determining the one or more optimized values of the operational parameter based on the comparing.
Abstract:
Some embodiments of this disclosure can improve measurement of target mark asymmetry in metrology apparatuses for improving accuracy in measurements performed in conjunction with lithographic processes. For example, a metrology system can include a projection system configured to receive a plurality of diffraction orders diffracted from a target on a substrate. The metrology system can further include a detector array and a waveguide device configured to transmit the plurality of diffraction orders between the projection system and the detector array. The detector array can be configured to detect each of the plurality of diffraction orders spatially separate from other ones of the plurality of diffraction orders.
Abstract:
Disclosed is a substrate, associated patterning device and a method for measuring a position of the substrate. The method comprises performing an alignment scan of an alignment mark to obtain simultaneously: a first measurement signal detected in a first measurement channel and a second measurement signal detected in a second measurement channel. The first and second measurement signals are processed by subtracting a first direction component of the first measurement signal from a first direction component of the second measurement signal to obtain a first processed signal, the first direction components relating to said first direction. The position of an alignment mark is determined with respect to the first direction from the first processed signal.
Abstract:
An alignment measurement system measures an alignment target on an object. A measurement illuminates the target and is reflected. The reflected measurement beam is split and its parts are differently polarized. A detector receives the reflected measurement beam. A processing unit determines alignment on the basis of the measurement beam received by the detector. An alternative arrangement utilizes an optical dispersive fiber to guide a multi-wavelength measurement beam reflected from the object to a detector.
Abstract:
A method of, and associated apparatuses for, performing a position measurement on an alignment mark including at least a first periodic structure having a direction of periodicity along a first direction. The method includes obtaining signal data relating to the position measurement and fitting the signal data to determine a position value. The fitting uses one of a modulation fit or a background envelope periodic fit.
Abstract:
An alignment apparatus includes an illumination system configured to direct one or more illumination beams towards an alignment target and receive the diffracted beams from the alignment target. The alignment apparatus also includes a self-referencing Interferometer configured to generate two diffraction sub-beams, wherein the two diffraction sub-beams are orthogonally polarized, rotated 180 degrees with respect to each other around an alignment axis, and spatially overlapped. The alignment apparatus further includes a beam analyzer configured to generate interference between the overlapped components of the diffraction sub-beams and produce two orthogonally polarized optical branches, and a detection system configured to determine a position of the alignment target based on light intensity measurement of the optical branches, wherein the measured light intensity is temporally modulated by a phase modulator.
Abstract:
A method for determining substrate deformation includes obtaining first measurement data associated with mark positions, from measurements of a plurality of substrates; obtaining second measurement data associated with mark positions, from measurements of the plurality of substrates; determining a mapping between the first measurement data and the second measurement data; and decomposing the mapping, by calculating an eigenvalue decomposition for the mapping, to separately determine a first deformation (e.g. mark deformation) that scales differently from a second deformation (e.g. substrate deformation) in the mapping between the data. The steps of determining a mapping and decomposing the mapping may be performed together using non-linear optimization.
Abstract:
A method for determining one or more optimized values of an operational parameter of a sensor system configured for measuring a property of a substrate. The method includes: determining a quality parameter for a plurality of substrates; determining measurement parameters for the plurality of substrates obtained using the sensor system for a plurality of values of the operational parameter; comparing a substrate to substrate variation of the quality parameter and a substrate to substrate variation of a mapping of the measurement parameters; and determining the one or more optimized values of the operational parameter based on the comparing.