A method of testing a photomask assembly includes placing the photomask assembly into a chamber, wherein the photomask assembly includes a pellicle attached to a first side of a photomask. The method further includes exposing the photomask assembly to a radiation source having a wavelength ranging from about 160 nm to 180 nm in the chamber to accelerate haze development, wherein the exposing of the photomask assembly includes illuminating an entirety of an area of the photomask covered by the pellicle throughout an entire illumination time and illuminating a frame adhesive attaching the pellicle to the photomask. The method further includes detecting haze of the photomask following exposing the photomask assembly to the radiation source. The method further includes predicting performance of the photomask assembly during a manufacturing process based on the detected haze of the photomask following exposing the photomask assembly to the radiation source.

A method of testing a photomask assembly includes placing the photomask assembly into a chamber, wherein the photomask assembly includes a pellicle attached to a first side of a photomask. The method further includes exposing the photomask assembly to a radiation source having a wavelength ranging from about 160 nm to 180 nm in the chamber to accelerate haze development, wherein the exposing of the photomask assembly includes illuminating an entirety of an area of the photomask covered by the pellicle throughout an entire illumination time and illuminating a frame adhesive attaching the pellicle to the photomask. The method further includes detecting haze of the photomask following exposing the photomask assembly to the radiation source. The method further includes predicting performance of the photomask assembly during a manufacturing process based on the detected haze of the photomask following exposing the photomask assembly to the radiation source.

A photolithography exposure of a photoresist coating on a semiconductor wafer uses an optical projection system to form a latent image. The photolithography exposure further uses a mask with a set of multiple pattern focus (MPF) marks. Each MPF mark of includes features having different critical dimension (CD) sizes. The latent image is developed to form a developed photoresist pattern. Dimension sizes are measured of features of the developed photoresist pattern corresponding to the features of the MPF marks having different CD sizes. A spatial focus map of the photolithography exposure is constructed based on the measured dimension sizes. To determine the focal distance at an MPF mark, ratios or differences may be determined between the measured dimension sizes corresponding to the features of the MPF marks having different CD sizes, and the focal distance at the location of the MFP mark constructed based on the determined ratios or differences.

Metrology methods and targets are provided for reducing or eliminating a difference between a device pattern position and a target pattern position while maintaining target printability, process compatibility and optical contrast—in both imaging and scatterometry metrology. Pattern placement discrepancies may be reduced by using sub-resolved assist features in the mask design which have a same periodicity (fine pitch) as the periodic structure and/or by calibrating the measurement results using PPE (pattern placement error) correction factors derived by applying learning procedures to specific calibration terms, in measurements and/or simulations. Metrology targets are disclosed with multiple periodic structures at the same layer (in addition to regular target structures), e.g., in one or two layers, which are used to calibrate and remove PPE, especially when related to asymmetric effects such as scanner aberrations, off-axis illumination and other error sources.

Metrology methods and targets are provided for reducing or eliminating a difference between a device pattern position and a target pattern position while maintaining target printability, process compatibility and optical contrast—in both imaging and scatterometry metrology. Pattern placement discrepancies may be reduced by using sub-resolved assist features in the mask design which have a same periodicity (fine pitch) as the periodic structure and/or by calibrating the measurement results using PPE (pattern placement error) correction factors derived by applying learning procedures to specific calibration terms, in measurements and/or simulations. Metrology targets are disclosed with multiple periodic structures at the same layer (in addition to regular target structures), e.g., in one or two layers, which are used to calibrate and remove PPE, especially when related to asymmetric effects such as scanner aberrations, off-axis illumination and other error sources.

A method for correcting a mask patter includes: acquiring an initial pattern of a mask, the initial pattern including a scribe line area and die areas which are spaced, and the scribe line area is located between two adjacent die areas, each of the die areas includes at least one die sub-area and at least one first sub-test element group (TEG) area, and the scribe line area includes scribe line sub-areas and second sub-TEG areas, the first sub-TEG area and the second sub-TEG area are adjacent to each other, and the first sub-TEG area and the second sub-TEG area constitute a TEG area; performing an optical proximity correction (OPC) on an area of the initial pattern excluding TEG areas, so as to acquire a final pattern.

A method for correcting a mask patter includes: acquiring an initial pattern of a mask, the initial pattern including a scribe line area and die areas which are spaced, and the scribe line area is located between two adjacent die areas, each of the die areas includes at least one die sub-area and at least one first sub-test element group (TEG) area, and the scribe line area includes scribe line sub-areas and second sub-TEG areas, the first sub-TEG area and the second sub-TEG area are adjacent to each other, and the first sub-TEG area and the second sub-TEG area constitute a TEG area; performing an optical proximity correction (OPC) on an area of the initial pattern excluding TEG areas, so as to acquire a final pattern.

A method of performing a lithography process includes providing a test pattern. The test pattern includes a first set of lines arranged at a first pitch, a second set of lines arranged at the first pitch, and further includes at least one reference line between the first set of lines and the second set of lines. The test pattern is exposed with a radiation source providing an asymmetric, monopole illumination profile to form a test pattern structure on a substrate. The test pattern structure is then measured and a measured distance correlated to an offset of a lithography parameter. A lithography process is adjusted based on the offset of the lithography parameter.

A multi-channel device and method for measuring the distortion and magnification of objective lens. The multi-channel device for measuring the distortion and magnification of objective lens comprises an illumination system, a reticle stage, a test reticle, a projection objective lens, a wafer stage and a multi-channel image plane sensor, wherein the multi-channel image plane sensor simultaneously measures the image placement shifts between actual image points and nominal image points after a plurality of object plane test marks are imaged by the projection objective lens, and calculates the distortion and magnification errors of the objective lens by fitting, which shortens the measurement time, eliminates the influence of wafer stage errors on the measurement accuracy and improves the measurement accuracy.

A multi-channel device and method for measuring the distortion and magnification of objective lens. The multi-channel device for measuring the distortion and magnification of objective lens comprises an illumination system, a reticle stage, a test reticle, a projection objective lens, a wafer stage and a multi-channel image plane sensor, wherein the multi-channel image plane sensor simultaneously measures the image placement shifts between actual image points and nominal image points after a plurality of object plane test marks are imaged by the projection objective lens, and calculates the distortion and magnification errors of the objective lens by fitting, which shortens the measurement time, eliminates the influence of wafer stage errors on the measurement accuracy and improves the measurement accuracy.