TECHNICAL FIELD

The presently disclosed subject matter relates, in general, to the field of examination of a specimen, and more specifically, to methods and systems capable of automated detection of defects belonging to a new class.

BACKGROUND

Current demands for high density and performance associated with ultra large scale integration of fabricated devices, require submicron features, increased transistor and circuit speeds, and improved reliability. Such demands require formation of device features with high precision and uniformity, which, in turn, necessitate careful monitoring of the fabrication process, including frequent and detailed examination of the devices while they are still in the form of semiconductor specimens.

The term “specimen” used in this specification should be expansively construed to cover any kind of wafer, mask, and other structures, combinations and/or parts thereof used for manufacturing semiconductor integrated circuits, magnetic heads, flat panel displays, and other semiconductor-fabricated articles.

The term “defect” used in this specification should be expansively construed to cover any kind of abnormality or undesirable feature formed on or within a specimen.

The complex manufacturing process of specimens is not error-free and such errors may cause faults in manufactured devices. The faults may include defects that can harm operation of the device, and nuisances, which may be defects, but do not cause any harm or malfunction of the manufactured device. By way of non-limiting example, defects may be caused during the manufacturing process, due to faults in the raw material, mechanical, electrical or optical errors, human errors, or others. Further, defects may be caused by spatio-temporal factors, such as temperature changes of the wafer occurring after one or more manufacturing stages during the examination process, which may cause some deformations of the wafer.

Unless specifically stated otherwise, the term “examination” used in this specification should be expansively construed to cover any kind of detection and/or classification of defects in an object. Examination is provided by using non-destructive examination tools during or after manufacture of the object to be examined. By way of non-limiting example, the examination process can include scanning (in a single or in multiple scans), sampling, reviewing, measuring, classifying and/or other operations provided with regard to the object or parts thereof, using one or more examination tools.

Likewise, examination can be provided prior to manufacture of the object to be examined and can include, for example, generating an examination recipe(s). It is noted that, unless specifically stated otherwise, the term “examination” or its derivatives used in this specification, is not limited with respect to the size of the inspected area(s), to the speed or resolution of the scanning, or to the type of examination tools. A variety of non-destructive examination tools includes, by way of non-limiting example, optical tools, scanning electron microscopes, atomic force microscopes, etc.

The examination process can include a plurality of examination steps. During the manufacturing process, the examination steps can be performed a multiplicity of times, for example after the manufacturing or processing of certain layers, or the like. Additionally or alternatively, each examination step can be repeated multiple times, for example for different specimen locations or for the same specimen locations with different examination settings.

By way of non-limiting example, run-time examination can employ a two-step procedure, e.g. inspection of a specimen followed by review of sampled defects. During the inspection step, the surface of a specimen or a part thereof (e.g. areas of interest, hot spots, etc.) is typically scanned at relatively high-speed and/or low-resolution. The captured inspection image is analyzed in order to detect defects and obtain locations and other inspection attributes thereof. At the review step the images of at least some of the defects detected during the inspection phase are, typically, captured at relatively low speed and/or high-resolution, thereby enabling verification, classification and, optionally, other analyses of the at least some of the defects. In some cases both phases can be implemented by the same inspection tool, and, in some other cases, these two phases are implemented by different inspection tools. It is noted that data informative of the captured images and/or derivatives thereof are referred to herein also as “images”.

GENERAL DESCRIPTION

Due to the large number of defects in a wafer, which may be in the order of magnitude of millions, it is impractical to expect that all defects are detected in one or more images captured during inspection, and that all detected defects are further checked. In accordance with certain aspects of the presently disclosed subject matter, it is important to make sure that defects located at specifically important or representative locations on the wafer, are indeed detected.

In accordance with certain aspects of the presently disclosed subject matter, there is provided an examination system to detect defects in a specimen. The system comprises a processing and memory circuitry (PMC) to: obtain an image of at least a part of a specimen, the image acquired by an examination tool, the image comprising a plurality of pixels; receive one or more characteristics of a defect of interest and a location of interest associated therewith; modify data informative of at least one pixel from the plurality of pixels and corresponding to the location of interest, wherein the modification is provided in accordance with the at least one characteristic of the defect of interest, thereby planting the defect of interest and obtaining modified image data; process the modified image data to detect locations of potential defects of the specimen in accordance with a detection recipe; and determine whether the detected locations include the location of interest.

In accordance with another aspects of the presently disclosed subject matter, there is provided a method of a specimen examination. The method comprises: obtaining an image of at least a part of a specimen, the image acquired by an examination tool comprising a plurality of pixels; receiving one or more characteristics of a defect of interest and a location of interest associated therewith; modifying data informative of at least one pixel from the plurality of pixels and corresponding to the location of interest, wherein the modification is provided in accordance with the at least one characteristic of the defect of interest, thereby planting the defect of interest and obtaining modified image data; processing the modified image data to detect locations of potential defects of the specimen in accordance with a detection recipe; and determining whether the detected locations include the location of interest.

In accordance with further aspects of the presently disclosed subject matter, and, optionally, in combination with other aspects, when the location of interest is not detected, the PMC can further modify the detection recipe to enable detecting the planted defect of interest at the location of interest. By way of non-limiting example, the detection recipe can comprise a set of instructions to: determining a grade for each pixel from the plurality of pixels, the grade indicative of a probability that the pixel reflects a defect or a part thereof; setting a threshold; and detecting as potential defects only pixels for which the respective grade exceeds the threshold. Subject to the location of interest not being detected, the PMC can further modify the threshold in the detection recipe to enable detecting the planted defect of interest at the location of interest.

In accordance with further aspects of the presently disclosed subject matter, and, optionally, in combination with other aspects, a value of one or more pixels can be changed to an absolute value. Optionally, obtaining the modified image data can comprise adding to a value of one or more pixels from the plurality of pixels, a second value provided as part of a characteristic. By way of non-limiting example, the location of interest can be absolute, repetitive, random, relative to a predetermined pattern, or relative to a predetermined location. By way of non-limiting example, a characteristic can be a type, a color, a geometrical characteristic, an amplitude, a parity, an electrical characteristic, or a physical characteristic.

Among advantages of certain embodiments of the presently disclosed subject matter is enabling a user to specify defects of interest and locations of interest associated therewith and to ensure that the detection recipe provides detection of the specified defects at the specified locations.

