Kla Instruments Corporation

Kla Tencor Corporation

Kla-tencor Technologies Corporation

Other

Mark Joseph Wihl

Michael E Fein

Damon Floyd Kvamme

Tao-Yi Fu

Marek Zywno

Yalin Xiong

Lih-Huah Yiin

Joseph M Blecher

Chun Guan

Steve Buchholz

William H Broadbent, Jr

Zain Kahuna Saidin

David Garth Emery

Robert A Comstock

Jun Ye

Stanley E Stokowski

William T Bell

Curt H Chadwick

David Alles

John D Greene

Stan Stokowski

George Q Chen

Kenneth Levy

Tim S Wihl

Robert R Sholes

P C Jann

Francis D Tucker, Iii

Matthias C Krantz

David A Joseph

Pei-Chun Chiang

Peter G Eldredge

Donald L Danielson

Bin-Ming B Isai

David J Harney

Walter I Novak

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

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.

A method for identifying lithographically significant defects. A photomask is illuminated to produce images that experience different parameters of the reticle as imaged by an inspection tool. Example parameters include a transmission intensity image and a reflection intensity image. The images are processed together to recover a band limited mask pattern associated with the photomask. A model of an exposure lithography system for chip fabrication is adapted to accommodate the band limited mask pattern as an input which is input into the model to obtain an aerial image of the mask pattern that is processed with a photoresist model yielding a resist-modeled image. The resist-modeled image is used to determine if the photomask has lithographically significant defects.

Method for detecting lithographically significant defects on reticles

Methods for detecting and classifying defects on a reticle are provided. One method includes acquiring images of the reticle at first and second conditions during inspection of the reticle. The first condition is different than the second condition. The method also includes detecting the defects on the reticle using one or more of the images acquired at the first condition. In addition, the method includes classifying an importance of the defects detected on the reticle using one or more of the images acquired at the second condition. The detecting and classifying steps are performed substantially simultaneously during the inspection.

Methods for detecting and classifying defects on a reticle

Techniques that use the design databases used in each of the expose/etch steps during construction of phase shift masks are described. A model or reference image is rendered, accounting for systematic variations, from the design databases to represent what a layer of the PSM should look like after processing. The reference image is compared to an optically acquired image of a specimen phase shift mask to find defects. The technique of the present invention can be used to inspect EAPSM, APSM and tritone masks. The technique inspects all layers in one pass and is therefore more efficient.

Multiple design database layer inspection

The ability to inspect photomasks for errors or defects in phase-shifters is greatly enhanced using optical techniques based on multiple modified radiation collection techniques. In particular, the apparatus and methods of the invention allows for errors in phase-shifters to be more accurately detected, even in the presence of regular amplitude objects such as grid lines. In one embodiment, the intensities of two slightly defocused images of phase objects corresponding to the same photomask location are compared. In a second embodiment, radiation having two Zernike point spread functions is used to obtain two slightly different phase sensitive images. Data collected and analyzed using this method provides much greater sensitivity to phase objects and errors in phase objects than prior art inspection systems. Embodiments include both scanning-type and projector-type optical architectures and may utilize radiation transmitted or reflected by a sample.

Efficient phase defect detection system and method

An automated photomask inspection apparatus including an XY state ( ) for transporting a substrate ( ) under test in a serpentine path in an XY plane, an optical system ( ) comprising a laser ( ), a transmission light detector ( ), a reflected light detector ( ), optical elements defining reference beam paths and illuminating beam paths between the laser, the substrate and the detectors and an acousto-optical beam scanner ( ) for reciprocatingly scanning the illuminating and reference beams relative to the substrate surface, and an electronic control, analysis and display system for controlling the operation of the stage and optical system and for interpreting and storing the signals output by the detectors. The apparatus can operate in a die-to-die comparison mode or a die-to-database mode.

Automated photomask inspection apparatus

An automated photomask inspection apparatus including an XY state (12) for transporting a substrate (14) under test in a serpentine path in an XY plane, an optical system (16) comprising a laser (30), a transmission light detector (34), a reflected light detector (36), optical elements defining reference beam paths and illuminating beam paths between the laser, the substrate and the detectors and an acousto-optical beam scanner (40, 42) for reciprocatingly scanning the illuminating and reference beams relative to the substrate surface, and an electronic control, analysis and display system for controlling the operation of the stage and optical system and for interpreting and storing the signals output by the detectors. The apparatus can operate in a die-to-die comparison mode or a die-to-database mode.

A method and apparatus for inspecting patterned transmissive substrates, such as photomasks, for unwanted particles and features occurring on the transmissive, opaque portions and at the transition regions of the opaque and transmissive portions of the substrate. A transmissive substrate is illuminated by a laser through an optical system comprised of a laser scanning system, individual transmitted and reflected light collection optics and detectors collect and generate signals representative of the light transmitted and reflected by the substrate as the substrate is scanned repeatedly in one axis in a serpentine pattern by a laser beam which is focused on the patterned substrate surface. The defect identification of the substrate is performed using only those transmitted and reflected light signals, and other signals derived from them, such as the second derivative of each of them. The actual defect identification is then performed by comparing combinations of at least two of those measured and derived signals. Simultaneously, defect and particle inspection using the same measured transmitted and reflected light signals. Additionally, phase shift and line widths on the substrate can also be performed simultaneously using the same transmitted light signal that is collected for defect analysis.

Automated photomask inspection apparatus and method

In each configuration, at least one TDI sensor is used to image the portions of interest of the substrate that are substantially uniformly or critically illuminated. In one configuration, the substrate is compared to the expected characteristic features prestored in memory. In a second configuration, a first and second pattern in a region of at least one substrate are inspected by comparing one pattern against the other and noting whether they agree with each other. This is accomplished by illuminating the two patterns, imaging the first pattern and storing its characteristics in a temporary memory, then imaging the second pattern and comparing it to the stored characteristics from the temporary memory. Then the comparisons continue sequentially with the second pattern becoming the first pattern in the next imaging/comparison sequence against a new second pattern. With each comparison whether there has been agreement between the two patterns is noted. After all of the patterns are sequentially compared, the bad ones are identified by identifying those that did not compare with other patterns in the test process. This inspection technique is useful for doing die-to-die inspections, as well as repeating patern inspections within the same die. A variation of the second configuration uses two TDI sensors to simultaneously image the first and second patterns eliminating the need for the temporary memory.

Automatic high speed optical inspection system

An automatic inspection system including an illuminator for illuminating a reticle or photomask to be inspected, while optically projecting a magnified image of the reticle or photomask onto a plurality of detector elements. A carriage assembly moves the object at a constant velocity to allow the detector elements to sequentially view the entire surface to be inspected. The detector elements are responsive to the intensity of light incident thereupon and are periodically scanned to obtain a two-dimensional measured representation of the object. A database adaptor formulates a two-dimensional representation from the design database description corresponding to the scanned object simultaneously and in synchronism with the scanning of the photomask or reticle. The measured and database adapted representation of the scanned object are input to a signal processor for alignment and defect detection. While the representations are shifted through a memory, an alignment circuit dynamically measures and corrects for misalignment between the representations, so that a defect detector can effectively compare the representations for defects. Additional correction of misalignment between the representations is obtained by modulating the size of the measured representation as detected by the detector elements. At the operator's option, a second measured image of a multi-cell reticle or photomask may be used for comparison as a substitute for the database representation.

Reticle inspection system

Optical inspection apparatus for detecting defects in a visually perceptible pattern including image acquistion means for inspecting the pattern on a pixel-by-pixel basis, developing digital data signals corresponding to each pixel and feeding the signals so developed to an imaging enhancement means. The imaging enhancement means compensates for equipment related degradations in the images and converts the digital data signal value corresponding to each pixel into a corrected signal value by operating on the digital data signal with a two dimensional finite impulse response filter. The corrected signal values of the image enhancement means are received by a defect detection means which evaluates the signal values for defects in the pattern. Any defects so determined are recorded and/or displayed on data recording means.

Automatic photomask inspection system having image enhancement means

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Tracy, CA, United States of America

Mark Joseph Wihl