Applied Materials South East Asia Pte. Ltd.

Negevtech Ltd.

Shai Silberstein

Dov Furman

Mark Wagner

Noam Dotan

Gad Neumann

Ram Segal

Daniel Mandelik

Tsafrir Avni

Ehud Tirosh

Martin David Abraham

Ran Zaslavsky

Arnon Gratch

Giora Eitan

Roy Kaner

Ori Gonen

Dan T Fuchs

Eran Tal

Gilad Shomrony

Yuval Dorphan

Effy Miklatzky

An optical inspection tool can automatically perform analysis/operations after the tool has generated data identifying defects (e.g. a defect list) from an inspection run of an object such as a semiconductor wafer. The tool can decouple post-inspection tasks from performing inspection runs so that one or more post-inspection tasks are performed on defect data from a previous inspection run while another inspection run is in progress. This can significantly improve the throughput of the tool when multiple inspections are performed, since the inspection run time effectively is shortened to include only the time the tool is actually used to acquire defect data. One or more post-inspection tasks can be performed, including, but not limited to, merging inspection runs, removing duplicate defects, removing straight-line false alarms, and characterizing defects.

Optical inspection tools featuring parallel post-inspection analysis

An optical inspection tool can feature a double-speed and other modes whereby the inspection rate is increased by using pixel binning. For instance, the tool may include an array of pixels provided by one or more detectors. Some or all of the pixels in one or more of the detectors may be binned according to inspection requirements. Based on the reduction in effective pixels due to the binning, in some embodiments, the rate of imaging and scanning rate of the wafer (or other object) can be increased. Different portions of the array may be binned differently to provide for increased throughput during inspections; for instance, the binning arrangement across an array can be correlated to the features that will be imaged using the array.

Optical inspection tool featuring multiple speed modes

A spatial mask printer may be used in conjunction with an optical inspection tool. The tool can be used to obtain a Fourier image of an inspected object, and a filter mask image can be designed to block certain aspects of the object's image in the Fourier plane corresponding to repetitive aspects of the imaged object. The filter mask image can then be printed and used in the tool during the inspection process. The mask image may be designed by hand or by computer and may be stored for later use. Filters may be automatically placed into the optical path of the inspection tool by a filter wheel, or may be housed in other filter banks. The printer may be configured to operate in a clean room environment, and may be integrated into the optical inspection tool.

Printed fourier filtering in optical inspection tools

An optical inspection system or tool can be configured to inspect objects using dynamic illumination where one or more characteristics of the illumination is/are adjusted to meet the inspection needs of different areas. For example, the illumination intensity may be increased or decreased as the tool inspects areas of memory and periphery features in a wafer die. In some embodiments, the adjustment can be based on data obtained during a pre-inspection setup sequence in which images taken based on illumination with varying characteristics are evaluated for suitability in the remainder of the inspection process.

Dynamic illumination in optical inspection systems

Fast on-line electro-optical detection of wafer defects by illuminating with a short light pulse from a repetitively pulsed laser, a section of the wafer while it is moved across the field of view of an imaging system, and imaging the moving wafer onto a focal plane assembly, optically forming a continuous surface of photo-detectors at the focal plane of the optical imaging system. The continuously moving wafer is illuminated by a laser pulse of duration significantly shorter than the pixel dwell time, such that there is effectively no image smear during the wafer motion. The laser pulse has sufficient energy and brightness to impart the necessary illumination to each sequentially inspected field of view required for creating an image of the inspected wafer die. A novel fiber optical illumination delivery system, which is effective in reducing the effects of source coherence is described. Other novel aspects of the system include a system for compensating for variations in the pulse energy of a Q-switched laser output, methods for autofocussing of the wafer imaging system, and novel methods for removal of repetitive features of the image by means of Fourier plane filtering, to enable easier detection of wafer defects.

System for detection of wafer defects

Inspection of objects, such as semiconductor wafers, can be performed using a diluted scan wherein not all of an inspected area is actually imaged. Instead, a dilution plan can be devised based on the desired amount of area to be skipped and the particular parameters of the inspection, such as the size of each unit area to be imaged or not imaged and the distribution features of the wafer. When the same area is inspected in multiple wafers, the wafers can be inspected in sets using a dilution plan whereby a wafer (or inspected area) can be statistically inspected using diluted scans of the set of wafers. Similarly a die or group of dies of a specified type can be statistically inspected using diluted scans of a set of dies (or group of dies). When statistical inspection is used, the end results of such inspections, such as defect densities and distributions, can be corrected to account for inaccuracies that may be introduced when certain portions are imaged more often than others due to the dilution plan.

Optical inspection including partial scanning of wafers

An inspection system can support operation in multiple states. For instance, when inspecting an article, such as a semiconductor wafer, the tool can switch between imaging multiple locations using respective detectors to another operating state wherein multiple detectors operating in multiple imaging modes inspect a single location. An inspection system may combine the use of multiple detectors for multiple locations and the use of multiple viewing angles or modes for the same locations and thereby achieve high throughput. The different imaging modes can comprise, for example, different collection angles, polarizations, different spectral bands, different attenuations, different focal positions relative to the wafer, and other different types of imaging.

Inspection tools supporting multiple operating states for multiple detector arrangements

A method for inspecting a wafer including a multiplicity of dies, the method including dividing an image of at least a portion of the wafer into a plurality of sub-images each representing a sub-portion of the wafer and selecting at least one defect candidate within each sub-image by comparing each sub-image to a corresponding sub-image of a reference including a representation, which is assumed to be faultless, of the portion of the wafer.

Method and apparatus for detecting defects in wafers including alignment of the wafer images so as to induce the same smear in all images

In an optical inspection tool, an image of an object under inspection, such as a semiconductor wafer, may be obtained using imaging optics defining a focal plane. Light comprising the image can be detected using multiple detectors which each register a portion of the image. The image of the object at the focal plane can be split into two, three, or more parts by mirrors or other suitable reflecting elements positioned tangent to the focal plane and/or with at least some portion at the focal plane with additional portions past the focal plane so that the focal plane lies between the imaging optics and the splitting apparatus. In some embodiments, reflective planes may be arranged to direct different portions to different detectors. Some reflective planes may be separated by a gap so that some portions of the light are directed while some portions pass through the gap. Other splitting elements may comprise a group of transmissive and reflective areas interspersed in an element positioned at or in the focal plane, with some portions of the light are reflected to detectors while other portions pass through the element(s) to other detectors. Splitting apparatuses and elements may be cascaded.

Image splitting in optical inspection systems

In an optical inspection tool, an image of an object under inspection, such as a semiconductor wafer, may be obtained using imaging optics defining a focal plane. Light comprising the image can be split into portions that are detected using multiple detectors which each register a portion of the image. The image of the object at the focal plane can be split into two, three, or more parts by polarization-based beam splitters and/or lenses positioned tangent to the focal plane. The splitting apparatus may comprise a pair of arrays of half-cylinder lenses comprising a convex side and a flat side. The arrays can be positioned with the cylinder axes perpendicular to one another and the flat sides facing each other. Thus, the pair of arrays can divide incoming light into a plurality of rectangular portions without introducing non-uniformities which would occur if several spherical lenses are configured for use in a rectangular array.

An inspection system may be configured to inspect objects, such as semiconductor wafers, using narrow-pulse broadband illumination. The illumination may be obtained in some embodiments using a laser configured to emit light into a material having a spectral broadening effect. The inspection system can include various filters which may be selectively placed in the illumination and/or imaging path in order to tune the spectrum of light impinging on the wafer and the light that is detected. The filters may include selectable filters, fixed filters, and filters whose characteristics can be adjusted in-place. In some embodiments, filters may be used to match the illumination/detection spectra of different tools. Additionally, the broadband illumination may be tuned between inspections and/or during inspections for best results. The system may support Fourier filtering whereby light, related to repetitive features of the object and in one or more wavelength sub-bands of the illumination, may be filtered.

Growing community of inventors

Rishon-Le-Zion, Israel

Shai Silberstein