Abstract: Disclosed are methods and systems for inspecting photolithographic reticles. A first and second reticle that were fabricated with a same design are obtained. A first and second reticle image of the first and second reticles are also obtained. The first reticle image is compared to the second reticle image to output a difference image having a plurality of difference events corresponding to candidate defects on either the first or second reticle. An inspection report of the candidate defects is then generated.

Abstract: An optical reticle inspection tool is used during a first inspection to obtain, for each set of one or more patch areas of the reticle, a reference average of multiple reference intensity values corresponding to light measured from sub-areas of each patch area. After using the reticle in photolithography processes, the optical reticle inspection tool is used during a second inspection to obtain, for each set of one or more patch areas, an average of multiple test intensity values corresponding to light measured from the sub-areas. The first and second inspections use the same tool setup recipe. A difference intensity map is generated, and such map comprises map values that each corresponds to a difference between each average of the test and reference intensity values for each set of one or more patches. The difference intensity map indicates whether the reticle has degraded over time more than a predefined level.

Abstract: Disclosed are methods and apparatus for inspecting a photolithographic reticle. An inspection tool is used to obtain a plurality of patch area images of each patch area of each die of a set of identical dies on a reticle. An integrated intensity value for each patch area image is determined. A gain is applied to the integrated intensity value for each patch area image based on a pattern sparseness metric of such patch area image and its relative value to other patch area images' pattern sparseness metric. A difference between the integrated intensity value of each patch of pairs of the dies, which each pair includes a test die and a reference die, is determined to form a difference intensity map of the reticle. The difference intensity map correlates with a feature characteristic variation that depends on feature edges of the reticle.

Abstract: An optical reticle inspection tool is used during an inspection to obtain, for each local area, an average of multiple reflected intensity values corresponding to light reflected from a plurality of sub-areas of each local area of the reticle. The optical reticle inspection tool is also used during the inspection to obtain, for each local area, an average of multiple transmitted intensity values corresponding to light transmitted through the sub-areas of each local area of the reticle. A combined intensity map is generated by combining, for each local area, the average of multiple reflected intensity values and the average of multiple transmitted intensity values such that a reticle pattern of the reticle is cancelled from the combined intensity map if the reticle has not degraded and such that the reticle pattern of the reticle is not cancelled out of the combined intensity map if the reticle has degraded.

Abstract: With an optical inspection tool, images of a plurality of patches of a plurality of dies of a reticle are obtained. The patch images are obtained so that each patch image is positioned relative to a same reference position within its respective die as another die-equivalent one of the patch images in each the other ones of the dies. For each patch image, an integrated value is determined for an image characteristic of sub-portions of such patch image. For each patch image, a reference value is determined based on the integrated values of the patch image's corresponding die-equivalent patch images. For each patch image, a difference between that patch image's integrated value and an average or median value of its die-equivalent patch images is determined whereby a significant difference indicates a variance in a pattern characteristic of a patch and an average or median pattern characteristic of its die-equivalent patches.

Abstract: Disclosed are methods and apparatus for inspecting a photolithographic reticle. An inspection tool is used to obtain a plurality of patch area images of each patch area of each die of a set of identical dies on a reticle. An integrated intensity value for each patch area image is determined. A gain is applied to the integrated intensity value for each patch area image based on a pattern sparseness metric of such patch area image and its relative value to other patch area images' pattern sparseness metric. A difference between the integrated intensity value of each patch of pairs of the dies, which each pair includes a test die and a reference die, is determined to form a difference intensity map of the reticle. The difference intensity map correlates with a feature characteristic variation that depends on feature edges of the reticle.

Abstract: An optical reticle inspection tool is used during an inspection to obtain, for each local area, an average of multiple reflected intensity values corresponding to light reflected from a plurality of sub-areas of each local area of the reticle. The optical reticle inspection tool is also used during the inspection to obtain, for each local area, an average of multiple transmitted intensity values corresponding to light transmitted through the sub-areas of each local area of the reticle. A combined intensity map is generated by combining, for each local area, the average of multiple reflected intensity values and the average of multiple transmitted intensity values such that a reticle pattern of the reticle is cancelled from the combined intensity map if the reticle has not degraded and such that the reticle pattern of the reticle is not cancelled out of the combined intensity map if the reticle has degraded.

Abstract: With an optical inspection tool, images of a plurality of patches of a plurality of dies of a reticle are obtained. The patch images are obtained so that each patch image is positioned relative to a same reference position within its respective die as another die-equivalent one of the patch images in each the other ones of the dies. For each patch image, an integrated value is determined for an image characteristic of sub-portions of such patch image. For each patch image, a reference value is determined based on the integrated values of the patch image's corresponding die-equivalent patch images. For each patch image, a difference between that patch image's integrated value and an average or median value of its die-equivalent patch images is determined whereby a significant difference indicates a variance in a pattern characteristic of a patch and an average or median pattern characteristic of its die-equivalent patches.

Abstract: A method for classifying images from a set of test images, including comparing each of the test images to reference images. Each of the test images is grouped with one of the reference images. All of the images in each group can be classified with a single classification.

Abstract: Disclosed are methods and apparatus for inspecting a sub-resolution assist features (SRAF) on a reticle. A test flux measurement for a boundary area that encompasses a width and a length portion of a test SRAF is determined, and at least one reference flux measurement for one or more boundary areas of one or more reference SRAF's is determined. The test flux measurement is compared with the reference flux measurements. The comparison is used to then determine whether the test SRAF is undersized or oversized. If the test SRAF is determined to be oversized, it may then be determined whether the test SRAF is defective based on the comparison using a first threshold.

Abstract: A method for selecting a set of features for monitoring a lithography process using a reticle, by identifying a set of candidate features, defining control regions around the candidate features, performing substrate level analysis using the reticle with different settings for the lithography process, determining which of the candidate features are most changed by the different settings, ranking the candidate features according to how much they are changed, and selecting the test set of features from those candidate features that are most changed.

Abstract: A computing system having at least one cluster. Each cluster has only one master server. The master server has at least one general processing unit, a relatively high speed data input adapted to send and receive data, a relatively low speed data input adapted to send and receive data, and a buffer memory adapted to buffer data between the relatively high speed data input and the relatively low speed data input. Each cluster also has at least one slave server, which has at least one general processing unit, and a relatively low speed data input adapted to send and receive data, the relatively low speed data input having data communication with the relatively low speed data input of the master server. In this manner, the relatively high speed data input, which tends to be very expensive, is present only in the master server, and is used for the high speed transfer of large amounts of data. However, the master server sends the data out to the slave servers on lower speed connections.

Abstract: Disclosed are methods and apparatus for inspecting a sub-resolution assist features (SRAF) on a reticle. A test flux measurement for a boundary area that encompasses a width and a length portion of a test SRAF is determined, and at least one reference flux measurement for one or more boundary areas of one or more reference SRAF's is determined. The test flux measurement is compared with the reference flux measurements. The comparison is used to then determine whether the test SRAF is undersized or oversized.

Abstract: The above and other needs are met by an inspection system having a sensor array that is connected to a high speed network connection, and is adapted to provide image data in regard to images of a substrate. A process node is also connected to the high speed network connection, and is adapted to received the image data over the high speed network connection and to analyze the image data to detect anomalies in the images. In this manner, commercially available hardware can be used to construct the inspection system, which thus overcomes many of the problems with expensive, unreliable, and inflexible prior art inspection systems.