A method and associated apparatuses for optimizing a sampling scheme which defines sampling locations on a bonded substrate, having undergone a wafer to wafer bonding process. The method includes determining a sampling scheme for a metrology process and optimizing the sampling scheme with respect to a singularity defined by a large overlay error and/or grid deformation at a central location on the bonded substrate to obtain a modified sampling scheme.

An alignment method and an alignment system are provided. The alignment method includes: providing a wafer including an exposed surface, wherein an alignment mark and a reference point with a reference distance are provided on the exposed surface; placing the wafer on a reference plane; performing an alignment measurement on the exposed surface to obtain a projection distance, configured as a measurement distance, between the alignment mark and the reference point on the reference plane; performing a levelling measurement between the exposed surface and the reference plane to obtain levelling data of the exposed surface; obtaining a distance, configured as an expansion reference value, between the alignment mark and the reference point in the exposed surface; obtaining an expansion compensation value based on a difference between the expansion reference value and the reference distance; and adjusting parameters of a photolithography process based on the expansion compensation value for an alignment.

A method of determining a position of a product feature on a substrate, the method includes: obtaining a plurality of position measurements of one or more product features on a substrate, wherein the measurements are referenced to either a positioning system used in displacing the substrate in between measurements or a plane parallel to the surface of the substrate; and determining a distortion component of the substrate based on the position measurements.

A structure of interest (T) is irradiated with radiation for example in the x-ray or EUV waveband, and scattered radiation is detected by a detector (19, 274, 908, 1012). A processor (PU) calculates a property such as linewidth (CD) or overlay (OV), for example by simulating (S16) interaction of radiation with a structure and comparing (S17) the simulated interaction with the detected radiation. The method is modified (S14a, S15a, S19a) to take account of changes in the structure which are caused by the inspection radiation. These changes may be for example shrinkage of the material, or changes in its optical characteristics. The changes may be caused by inspection radiation in the current observation or in a previous observation.

Methods and apparatuses for estimating at least part of a shape of a surface of a substrate usable in fabrication of semiconductor devices. Such a method includes: obtaining at least one focal position of the surface of the substrate measured by an inspection apparatus, the at least one focal position for bringing targets on or in the substrate within a focal range of optics of the inspection apparatus; and determining the at least part of the shape of the surface of the substrate based on the at least one focal position.

Various embodiments of aligning wafers are described herein. In one embodiment, a photolithography system aligns a wafer by averaging individual via locations. In particular, some embodiments of the present technology determine the center locations of individual vias on a wafer and average them together to obtain an average center location of the set of vias. Based on a comparison of the average center location to a desired center location, the present technology adjusts the wafer position. Additionally, in some embodiments, the present technology compares wafer via patterns to a template and adjusts the position of the wafer based on the comparison.

A method of transferring a flexible layer to a substrate makes use of a partial bulge in the flexible layer, which does not make contact with the substrate. The partial bulge advances to the location of an alignment marker on the substrate. When alignment adjustments are needed, they are made with the partial bulge in place so that more reproducible positioning is possible when fully advancing the flexible layer against the substrate.

A lithography system for generating grating structures is provided having a multiple column imaging system located on a bridge capable of moving in a cross-scan direction, a mask having a grating pattern with a fixed spatial frequency located in an object plane of the imaging system, a multiple line alignment mark aligned to the grating pattern and having a fixed spatial frequency, a platen configured to hold and scan a substrate, a scanning system configured to move the platen over a distance greater than a desired length of the grating pattern on the substrate, a longitudinal encoder scale attached to the platen and oriented in a scan direction and at least two encoder scales attached to the platen and arrayed in the cross-scan direction wherein the scales contain periodically spaced alignment marks having a fixed spatial frequency.

A method for layoutless overlay control is provided. In some embodiments, a target layer covering a workpiece is patterned using a reticle. The patterning forms a plurality of exposure fields arranged according to a first exposure field layout. Alignment of the exposure fields relative to the workpiece is measured to generate displacement vectors. An inter-field model and an intra-field model are trained using the displacement vectors and a reference field layout. The intra-field model is transformed for use with a second exposure field layout, where the second exposure field layout is different than the first exposure field layout. Overlay corrections are generated based on the trained inter-field model and the transformed intra-field model.

In an exposure apparatus and a method for defocus and tilt error compensation, each of alignment sensors (500a, 500b, 500c, 500d, 500e, 500f) corresponds to and has the same coordinate in the first direction as a respective one of focusing sensors (600a, 600b, 600c, 600d, 600e, 600f), so that each of the alignment sensors (500a, 500b, 500c, 500d, 500e, 500f) is arranged on the same straight line as a respective one of the focusing sensors (600a, 600b, 600c, 600d, 600e, 600f). As such, alignment marks can be characterized with both focusing information and alignment information. This enables the correction of errors in the alignment information and thus achieves defocus and tilt error compensation, resulting in significant improvements in alignment accuracy and the production yield.