A method of inferring a value for a first processing parameter of a lithographic process, the first processing parameter being subject to a coupled dependency of a second processing parameter. The method includes determining a first metric and a second metric from measurement data, each of the first metric and second metric being dependent on both the first processing parameter and second processing parameter The first metric shows a stronger dependence to the first processing parameter than the second processing parameter and the second metric shows a stronger dependence to the second processing parameter than the first processing parameter. The value for the first processing parameter is inferred from the first and second metrics.

From a reference waveform 112 and a BSE signal waveform 211 that is extracted from a backscattered electron image and indicates a backscattered electron signal intensity from a pattern along a first direction, a difference waveform indicating a relationship between the backscattered electron signal intensity and a difference between a coordinate of the BSE signal waveform and a coordinate of the reference waveform which have the same backscattered electron signal intensity is generated, and presence or absence of a shielded region 203 that is not irradiated with a primary electron beam on a side wall of the pattern is determined based on the difference waveform. The reference waveform indicates a backscattered electron signal intensity from a reference pattern along the first direction in which the side wall is formed perpendicularly to an upper surface and a bottom surface of the pattern when the reference pattern is scanned with the primary electron beam.

A method including: computing a value of a first variable of a pattern of, or for, a substrate processed by a patterning process by combining a fingerprint of the first variable on the substrate and a certain value of the first variable; and determining a value of a second variable of the pattern based at least in part on the computed value of the first variable.

Methods and systems for measuring optical properties of transistor channel structures and linking the optical properties to the state of strain are presented herein. Optical scatterometry measurements of strain are performed on metrology targets that closely mimic partially manufactured, real device structures. In one aspect, optical scatterometry is employed to measure uniaxial strain in a semiconductor channel based on differences in measured spectra along and across the semiconductor channel. In a further aspect, the effect of strain on measured spectra is decorrelated from other contributors, such as the geometry and material properties of structures captured in the measurement. In another aspect, measurements are performed on a metrology target pair including a strained metrology target and a corresponding unstrained metrology target to resolve the geometry of the metrology target under measurement and to provide a reference for the estimation of the absolute value of strain.

The present invention provides an image processing method for CDSEM for determining a measuring range of an image of a target pattern measured by a CDSEM machine. The image processing method of CDSEM comprises: obtaining a first gray scale image based on the image of the target pattern; performing Fourier transform to the first gray scale image to obtain a first frequency spectrum distribution; filtering out frequency spectrum components whose absolute values of ordinate are greater than preset threshold in the first frequency spectrum distribution to obtain a second frequency spectrum distribution, the preset threshold relates to the background noise and the signal frequency of SRAF features; and determining the measuring range based on the second frequency spectrum distribution.

Roughness measurement corrects a machine difference utilizing first PSD data indicating power spectral density of a line pattern measured for a line pattern formed on a wafer for machine difference management by a reference machine in roughness index calculation and second PSD data indicating power spectral density of a line pattern measured for the line pattern formed on the wafer for machine difference management by a correction target machine are used to obtain a correction method for correcting the power spectral density of the second PSD data to the power spectral density of the first PSD data, power spectral density of a line pattern is measured as third PSD data from a scanning image of the line pattern, and corrected power spectral density obtained by correcting the power spectral density of the third PSD data by the obtained correction method is calculated.

A metrology method comprising: performing a first exposure on a substrate to form a first patterned layer including a plurality of first target units, each first target unit comprising a first target feature; performing a second exposure on the substrate to form a second patterned layer comprising second target units overlying respective ones of the first target units, each of the second target units having a second target feature, wherein ones of the second target units have the second target feature positioned at respectively different offsets relative to a reference position: imaging the second target units overlaid on the first target units; and determining an edge placement error based on positions of edges of second target features in second target units relative to edges of the first target feature of the underlying first target unit.

A combined OCD and photoreflectance system and method for improving the OCD performance in measurements of optical properties of a target sample. The system comprises (a) either a single channel OCD set-up comprised of a single probe beam configured in a direction normal/oblique to the target sample or a multi-channel OCD set-up having multiple probe beams configured in normal and oblique directions to the target sample for measuring the optical properties of the target sample, (b) at least one laser source for producing at least one laser beam, (c) at least one modulation device to turn the at least one laser beam into at least one alternatingly modulated laser beam, and (d) at least one spectrometer for measuring spectral components of the at least one light beam reflecting off said target sample; wherein the at least one alternatingly modulated laser beam is alternatingly modulating the spectral reflectivity of the target sample,

A focus-sensitive metrology target may be formed and read-out by a fabrication tool. A resulting overlay signal may be translated into a focus offset by comparison to a previously-determined calibration curve. One or more translated signals may be fed back to the fabrication tool for focus correction or used for prediction of on-device overlay (correction of overlay metrology results). In one embodiment, focus and overlay may be measured using a single target, where one portion of the target is formed on a first layer and includes a focus-sensitive design, and where another portion of the target is formed on a second layer and includes a relatively less focus-sensitive design. In some embodiments, a relative difference in focus response may be used to estimate an impact of focus error on device overlay and calculate non-zero offset contributions.

A method for controlling a lithographic apparatus, and associated apparatuses. The method is configured to provide product structures to a substrate in a lithographic process and includes determining optimization data. The optimization data includes measured and/or simulated data of at least one performance parameter associated with the product structures and/or their arrangement which are to be applied to the substrate in the lithographic process. Substrate specific metrology data as measured and/or modeled before the providing of product structures to the substrate is determined, the substrate specific metrology data including metrology data relating to a characteristic of the substrate to which the structures are being applied and/or the state of the lithographic apparatus at the time that the structures are applied to the substrate. The method further includes optimizing control of the lithographic apparatus during the lithographic process based on the optimization data and the substrate specific metrology data.