Kla Tencor Corporation

Kla-tencor Technologies Corporation

Yalin Xiong

Carl Hess

Rui-Fang Shi

Mark Joseph Wihl

Abdurrahman Sezginer

Zain Saidin

John Fielden

Sterling G Watson

Lih-Huah Yiin

Weston L Sousa

Joseph M Blecher

Chun Guan

Patrick LoPresti

Robert A Comstock

Joe Blecher

Lisheng Gao

Stanley E Stokowski

Damon Floyd Kvamme

Moshe E Preil

Lance Glasser

Grace H Chen

Xiaochun Li

Junqing Huang

David Alles

Stan Stokowski

Yanwei Liu

Ge Cong

Hawren Fang

Ruifang Shi

Pavan Kumar

Vinayak Dattatreya Phalke

Systems and methods increase the signal to noise ratio of optical inspection of wafers to obtain higher inspection sensitivity. The computed reference image can minimize a norm of the difference of the test image and the computed reference image. A difference image between the test image and a computed reference image is determined. The computed reference image includes a linear combination of a second set of images.

Wafer inspection using difference images

Block-to-block reticle inspection includes acquiring a swath image of a portion of a reticle with a reticle inspection sub-system, identifying a first occurrence of a block in the swatch image and at least a second occurrence of the block in the swath image substantially similar to the first occurrence of the block and determining at least one of a location, one or more geometrical characteristics of the block and a spatial offset between the first occurrence of the block and the at least a second occurrence of the block.

Block-to-block reticle inspection

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.

Inspection of photomasks by comparing two photomasks

A reticle that is within specifications is inspected to generate baseline candidate defects and their location and size. After using the reticle in photolithography, the reticle is inspected to generate current candidate defects and their location and size. An inspection report of filtered candidate defects and their images is generated so that these candidate defects include a first subset of the current candidate defects and their images and exclude a second subset of the current candidate defects and their images. Each of the first subset of candidate defects has a location and size that fails to match any baseline candidate defect's location and size, and each of the excluded second subset of candidate defects has a location and size that matches a baseline candidate defect's location and size.

Monitoring changes in photomask defectivity

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.

Delta die and delta database inspection

Methods and systems for integrated multi-pass reticle inspection are provided. One method for inspecting a reticle includes acquiring at least first, second, and third images for the reticle. The first image is a substantially high resolution image of light transmitted by the reticle. The second image is a substantially high resolution image of light reflected from the reticle. The third image is an image of light transmitted by the reticle that is acquired with a substantially low numerical aperture. The method also includes detecting defects on the reticle using at least the first, second, and third images for the reticle in combination.

Integrated multi-pass inspection

A reticle that is within specifications is inspected so as to generate a baseline event indicating a location and a size value for each unusual reticle feature. After using the reticle in photolithography, the reticle is inspected so as to generate a current event indicating a location and a size value for each unusual reticle feature. An inspection report of candidate defects and their images is generated so that these candidate defects include a first subset of the current events and their corresponding candidate defect images and exclude a second subset of the current events and their corresponding excluded images. Each of the first included events has a location and size value that fails to match any baseline event's location and size value, and each of the excluded second events has a location and size value that matches a baseline event's location and size value.

An EUV integrated circuit fabrication method and system EUV that includes blank inspection, defect characterization, simulation, pattern compensation, modification of the mask writer database, inspection and simulation of patterned masks, and patterned mask repair. The system performs blank inspection to identify defects at multiple focal planes within the blank. The mask can be relocated on the blank and alterations to the pattern can be developed to compensate for the defects prior to prior to patterning the mask. Once the mask has been patterned, the reticle is inspected to identify any additional or remaining defects that were not picked up during blank inspection or fully mitigated through pattern compensation. The patterned reticle can then be repaired prior to integrated circuit fabrication.

Method and apparatus for inspecting a reflective lithographic mask blank and improving mask quality

Provided are novel methods and systems for inspecting photomasks to identify lithographically significant contamination defects. Inspection may be performed without a separate reference image provided from a database or another die. Inspection techniques described herein involve capturing one or more test images of a photomask and constructing corresponding test 'simulation' images using specific lithographic and/or resist models. These test simulation images simulate printable and/or resist patterns of the inspected photomask. Furthermore, the initial test images are used in parallel operations to generate 'synthetic' images. These images represent a defect-free photomask pattern. The synthetic images are then used for generating reference simulation images, which are similar to the test simulation images but are free from lithographically significant contamination defects. Finally, the reference simulation images are compared to the test simulation images to identify the lithographically significant contamination defects on the photomask.

Wafer plane detection of lithographically significant contamination photomask defects

Methods and systems for classifying defects detected on a reticle are provided. One method includes determining an impact that a defect detected on a reticle will have on the performance of a device being fabricated on a wafer based on how at least a portion of the reticle prints or will print on the wafer. The defect is located in the portion of the reticle. The method also includes assigning a classification to the defect based on the impact.

Methods and systems for classifying defects detected on a reticle

Various computer-implemented methods are provided. One method for generating a process for inspecting reticle layout data includes identifying a first region in the reticle layout data. A printability of the first region is more sensitive to changes in process parameters than a printability of a second region in the reticle layout data. The method also includes assigning one or more inspection parameters to the first region and the second region such that the first region will be inspected during the process with a higher sensitivity than the second region. Another method includes inspecting the first region with a higher sensitivity than the second region. An additional method includes simulating how the reticle layout data will print. Simulation of the first and second regions is performed with one or more different simulation parameters such that the first region is simulated with a higher fidelity than the second region.

Methods for simulating reticle layout data, inspecting reticle layout data, and generating a process for inspecting reticle layout data

Methods and apparatus relating to the inspection of photomasks are described. In an embodiment, detection of thin line or sub-resolution assist features may be used for selective sensitivity during photomask inspection. Other embodiments are also described.

Detection of thin line for selective sensitivity during reticle inspection

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.

Method for detection of oversized sub-resolution assist features

A method and tool for generating reconstructed images that model the high NA effects of a lithography tool used to image patterns produced by a mask. Comparison of the reconstructed images with reference images characterize the mask. The method involves providing a mask reticle for inspection. Generating matrix values associated with a high NA corrective filter matrix that characterizes a high NA lithography system used to print from the mask. Illuminating the mask to produce a patterned illumination beam that is filtered with filters associated with the high NA corrective filter matrix elements to obtain a plurality of filtered beams that include raw image data that is processed to obtain a reconstructed image that is further processed and compared with reference images to obtain mask characterization information.

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Union City, CA, United States of America

Yalin Xiong