WO2006019446A2 - Double inspection de reticule ou de plaquette - Google Patents

Double inspection de reticule ou de plaquette Download PDF

Info

Publication number
WO2006019446A2
WO2006019446A2 PCT/US2005/015932 US2005015932W WO2006019446A2 WO 2006019446 A2 WO2006019446 A2 WO 2006019446A2 US 2005015932 W US2005015932 W US 2005015932W WO 2006019446 A2 WO2006019446 A2 WO 2006019446A2
Authority
WO
WIPO (PCT)
Prior art keywords
frame
frame image
article
view
image
Prior art date
Application number
PCT/US2005/015932
Other languages
English (en)
Other versions
WO2006019446A3 (fr
Inventor
Ron Naftali
Yochanan Madmon
Gavriel Speyer
Oren Boiman
Original Assignee
Applied Materials Israel, Ltd.
Applied Materials, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/US2004/023395 external-priority patent/WO2005010510A1/fr
Application filed by Applied Materials Israel, Ltd., Applied Materials, Inc. filed Critical Applied Materials Israel, Ltd.
Publication of WO2006019446A2 publication Critical patent/WO2006019446A2/fr
Publication of WO2006019446A3 publication Critical patent/WO2006019446A3/fr

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
    • G03F1/82—Auxiliary processes, e.g. cleaning or inspecting
    • G03F1/84—Inspecting
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/88—Investigating the presence of flaws or contamination
    • G01N21/95—Investigating the presence of flaws or contamination characterised by the material or shape of the object to be examined
    • G01N21/956—Inspecting patterns on the surface of objects

Definitions

  • This invention relates to inspection of articles related to the manufacture of semicon ⁇ ductor devices. More particularly, this invention relates to the inspection of photomasks or reti ⁇ cles used in the photolithographic manufacture of semiconductor devices.
  • Each photolithographic reticle includes an intricate set of geometric patterns corresponding to the circuit components to be integrated onto the wafer.
  • the transfer of the reticle pattern onto the photoresist layer is performed by an optical exposure tool such as a scanner or a stepper, which directs light or other radiation through the reticle to expose the photo ⁇ resist.
  • the photoresist is thereafter developed to form a photoresist mask, and underlying polysilicon insulation or a metal layer is selectively etched in accordance with the mask to form features such as lines or gates.
  • phase shift masks require not only finding "conventional" defects, such as particles, but also detecting errors in the thickness of various regions of the mask. Numerous systems for mask inspection have been developed in response to the growing demands of the electronic industry.
  • any defect on the reticle such as extra or missing chrome, may transfer onto the fabricated wafer in a repeated manner.
  • any defect on the reticle would drastically reduce the yield of the fabrication line.
  • the in ⁇ spection is generally performed by an optical system, using transmitted, reflected, or both types of illuminations.
  • An example of such a system is the ARIS21i reticle inspection system available from Applied Materials, Inc., 2821 Scott Boulevard, Santa Clara, CA 95050.
  • die-to-die inspection in which a die is compared to a purportedly identical die on the same reticle
  • die-to-database inspection in which data pertaining to a given die is compared to information in a database, which could be the one from which the reticle was gener ⁇ ated.
  • die-to-golden-die a reference die is chosen for inspecting wafers.
  • design rule based inspection in which the die has to fulfill line width and spacing requirements, and feature shapes should fit predefined shapes.
  • Known inspection techniques typically image the article under inspection using a large magnification onto a solid state imaging device, such as a charge-coupled device (CCD) camera.
  • CCD charge-coupled device
  • the imaging technique requires the article to be illuminated.
  • the brightness of the il ⁇ luminating source is a key factor in the ability to speed the inspection by reducing the integration time of the camera.
  • the patterns on wafers become smaller, it becomes necessary to use smaller wavelengths in order to be able to detect the patterns. This is due to the fact that the physical resolution limit depends linearly on the illumination wavelength, and further due to in ⁇ terference effects, which require that the inspection be done at a wavelength similar to the one used in the lithographic process.
  • FA rate false alarm rate
  • Optical inspection systems using CCD/CMOS cameras can suffer from con ⁇ tamination or scratches on the optical surfaces and from detector problems (blemishes, dead pix ⁇ els, etc.)
  • Such defects can cause artifact images at the CCD plane of the inspection system, espe ⁇ cially under high coherence illumination, which may hide actual defects on the article under in ⁇ spection.
  • the artifacts dynamically change, depending on the article pattern, since the pattern on the article influences the diffraction pattern generated at the CCD plane by a contaminant particle or scratch.
  • the article patterns thus affect the FA rate, an effect that can not be neutralized by calibration procedures. For efficient inspection, there is a need to maintain a low FA rate, while still providing high inspection throughput.
  • each region on an article under inspection such as a mask
  • consecutive frames overlap by at least 50 per cent.
  • sys ⁇ tem blemishes have approximately constant frame coordinates
  • mask defects have constant reticle coordinates, but inconstant scan frame coordinates.
  • the overlapping frame images may be captured by scanning a single camera over the article at reduced speed. In some embodiments, however, in order to maintain high throughput, multiple cameras with adjacent or overlapping fields of view scan over the article together, in parallel. As different cameras generally have blemishes in different frame locations, the output of one camera can be used to detect defects positioned at a blemish location of another.
  • Imaging optics comprising a system of mirrors and beamsplitters are positioned so as to direct a portion of the light returning from the field of view onto a respective camera.
  • the cameras may be positioned, for example, so that each camera is at a different optical distance from the article and thus images the article at a dif ⁇ ferent defocus. This mode is useful, inter alia, in process window inspection, for checking printability of a mask over a given defocus range.
  • beam directing optics are operative in a first mode in which overlapping images are acquired, or in a second, fast scan mode, in which each camera images its own field of view in the article plane without overlapping.
  • multiple passes across a mask are made in which there is an overlap between slices that are orthogonal to the scan direction.
  • the invention provides a method of inspecting an article, which is carried out by ac ⁇ quiring a first frame image of a first field of view of the article, and acquiring a second frame image of a second field of view of the article, wherein the first field of view and the second field of view overlap, and identifying blemish locations having substantially constant frame coordi ⁇ nates on the first frame image and the second frame image.
  • An aspect of the method includes identifying a first defect location on the first frame image and a second defect location on the second frame image.
  • the first defect location is dis ⁇ placed from the second defect location by a frame displacement that is defined by the overlap, wherein at least one of the first defect location and the second defect location is distinct from any of the blemish locations.
  • both of the first defect location and the second defect location are distinct from the blemish locations.
  • a further aspect of the method includes adjusting the overlap such that the frame displacement is distinct from displacements between pairs of system blemishes that are aligned in a scan direction.
  • One aspect of the method includes varying a detection threshold of the first frame image and the second frame image, and repeatedly identifying a first defect location on the first frame image and a second defect location on the second frame image, so as to identify all defect locations on the article.
  • Still another aspect of the method includes applying a super-resolution technique to the first frame image and the second frame image, and repeating the identification of the first defect location on the first frame image and the second defect location on the second frame im ⁇ age, so as to identify all defect locations on the article.
  • the first frame image the second frame image are acquired by impinging pulsed coherent light on the article.
  • the focal plane of the first frame image differs from the focal plane of the second frame image.
  • the overlap of the first field of view and the second field of view is oriented in the scan direction.
  • the overlap of the first field of view and the second field of view is oriented orthogonal to the scan direction.
  • the overlap is at least 50% of an area of the first frame image.
  • the invention provides a method of inspecting an article employing an optical imag ⁇ ing system, which is carried out by preparing a pre-scan mask of blemishes of the optical imag ⁇ ing system, determining blemish displacements between pairs of the blemishes that are aligned in the scan direction, selecting a frame overlap of consecutive image frames of the article that is distinct from all of the blemish displacements, acquiring a first frame image and acquiring a sec- ond frame image of the article that overlaps the first frame image at the frame overlap, and mask ⁇ ing the first frame image and the second frame image with the pre-scan mask.
  • An additional aspect of the method includes identifying a first defect location on the first frame image and a second defect location on the second frame image, wherein the first de ⁇ fect location is displaced from the second defect location by a frame displacement that is defined by the frame overlap between the first frame image and the second frame image, wherein at least one of the first defect location and the second defect location is distinct from any of the blem ⁇ ishes on the pre-scan mask.
  • An additional aspect of the method includes varying a detection threshold of the first frame image and the second frame image, and repeating the procedure for identifying the first defect location on the first frame image and the second defect location on the second frame im ⁇ age, so as to identify all defect locations on the article.
  • the invention provides an optical inspection apparatus of inspecting an article, in ⁇ cluding a scanner for illuminating the article in a scan direction, a detector for detecting frame images of the article, beam directing optics for directing light from the article to the detector, a controller for controlling the scanner and the detector to acquire the frame images portions at a frame overlap, and an image processor adapted to prepare a pre-scan mask of system blemishes.
  • the frame overlap is selected to be distinct from all displacements between pairs of the blem ⁇ ishes that are aligned in the scan direction.
  • the image processor is further adapted to mask the frame images with the pre-scan mask.
  • the detector includes a plurality of cameras that simultaneously image overlapping fields of view on the article.
  • the detector in ⁇ cludes a plurality of cameras
  • the controller in a first mode of operation configures the cam- eras to image overlapping fields of view on the article and in a second mode of operation config ⁇ ures the cameras to image adjacent non-overlapping fields of view thereon.
  • the invention provides a method of inspecting an article, which is carried out by di ⁇ recting a beam from the article through optics along a plurality of optical paths, disposing a first camera in one of the optical paths, the first camera having a first field of view of the article and disposing a second camera in another of the optical paths, the second camera having a second field of view of the article, wherein the first field of view and the second field of view have an overlap.
  • the method is further carried out by acquiring a first frame image of the article with the first camera, and acquiring a second frame image of the article with the second camera, identify ⁇ ing blemish locations having substantially constant frame coordinates on the first frame image and the second frame image, and identifying a defect in the first frame image and in the second frame image, wherein the frame displacement of the defect corresponds to the overlap, and wherein a location of the defect on at least one of the first frame image and the second frame im ⁇ age avoids the frame coordinates of the blemish locations thereon.
  • frame coordinates of the defect on the first frame image and on the second frame image are distinct from the blemish locations.
  • a further aspect of the method includes adjusting the overlap such that the frame displacement is unequal to any displacement between members of pairs of system blemishes that are aligned in a scan direction.
  • the invention provides an optical inspection apparatus, including a plurality of im ⁇ age sensors, and beam directing optics, which are adapted to direct a collection beam from a sur ⁇ face of an article under inspection onto the image sensors.
  • the optics di ⁇ rect the collection beam onto the image sensors, so that all the image sensors have a common field of view, and in a second configuration the image sensors have different fields of view.
  • the optics impinge the collection beam onto the image sensors with equal fluence.
  • the image sensors comprise three detectors, and the optics comprise two mirrors.
  • the image sensors are focused on different planes relative to a surface of the article.
  • the first field of view overlaps the second field of view.
  • Still another aspect of the optical inspection apparatus includes at least one beam splitter disposed in the collection beam for directing at least portions of the collection beam to ⁇ ward the image sensors, respectively.
  • the beam splitter includes two beam splitters, and the image sensors comprise three image sensors.
  • One aspect of the optical inspection apparatus includes a mirror disposed in the col ⁇ lection beam, and a beam blocking means moveable to block a portion of the collection beam from reaching the mirror, and an opto-mechanical subsystem for displacing the beam blocking means and the beam splitter between operating positions and non-operating positions, and a scanner, wherein the article is scanned relative the optics in a scan direction.
  • the beam blocking means is interposed by the opto-mechanical subsystem so as to block the portion of the collection beam, and the beam splitter is disposed within the collection beam, and in the second configuration the beam blocking means and the beam splitter are displaced by the opto-mechanical subsystem external to the collection beam.
  • the invention provides a method of inspecting an article, which is carried out by dis ⁇ posing a plurality of image sensors to image the article, and directing a collection beam from a surface of the article under inspection onto the image sensors. In a first configuration, all the image sensors have a common field of view, and in a second configuration, the image sensors have different fields of view.
  • Fig. 1 is a schematic block diagram illustrating an opto-mechanical system for in ⁇ specting an article, which is constructed and operative in accordance with a disclosed embodi ⁇ ment of the invention
  • FIG. 2 is a flow diagram illustrating a multi-pass operation of the system shown in Fig. 1, in accordance with a disclosed embodiment of the invention
  • Fig 3 is an image of a calibration frame prepared in accordance with a disclosed em ⁇ bodiment of the invention.
  • FIG. 4 is a schematic diagram of an optical system suitable for a scanning mode of operation, wherein each region on an article under inspection is viewed at least twice, which is constructed and operative in accordance with a disclosed embodiment of the invention;
  • Fig. 5 is a schematic diagram of an optical system for performing multi-focal optical inspection suitable for evaluation of a process window, which is constructed and operative in accordance with a disclosed embodiment of the invention
  • Fig. 6 is a composite schematic diagram of an opto-mechanical system in which con ⁇ figurations of the embodiments shown in Fig. 4 and Fig. 5 are interchangeable, which is con ⁇ structed and operative in accordance with a disclosed embodiment of the invention.
  • FIG. 7 schematically illustrates a fast scanning mode of operation using three cam ⁇ eras, in accordance with a disclosed embodiment of the invention.
  • FIG. 8 schematically illustrates multi-pass scanning in accordance with a disclosed embodiment of the invention.
  • Fig. 1 is a sche ⁇ matic block diagram illustrating an opto-mechanical system 10 for inspecting an article 12, which is constructed and operative in accordance with a disclosed embodiment of the invention.
  • the system 10 is shown as operating in a reflective mode for clarity of pres ⁇ entation.
  • inspection devices operating in a transmissive mode, or in both a transmissive and a reflective mode are within the contemplation of the inven ⁇ tion.
  • the article 12, which is typically a wafer, a mask, or a reticle, is positioned on a x-y stage 14, which moves the article 12 in two directions within an inspection plane in a predetermined pattern of motion.
  • the system 10 includes a light source 16, preferably a coherent light source, such as a laser, located on one side of the article 12.
  • the light source 16 may be a continuous wave laser, or may be a pulsed laser, typically emitting short-wavelength laser beams in the UV or deep UV region.
  • An illuminating beam 18 emitted by the light source 16 enters a beam direct ⁇ ing subsystem 20, which includes transmission beam directing optics 22, and an optional coher ⁇ ence reduction optical apparatus 24.
  • the beam directing subsystem 20 directs the beam 18 onto the surface of the article 12, and has specialized beam collection elements, which are disclosed in further detail hereinbelow. It should be noted that other means of directing the beam 18 onto the article 12, including other optical paths defined by suitable structure, also may be used.
  • the light beam hitting the surface of article 12 is reflected or transmitted as a collec ⁇ tion beam via the beam directing subsystem 20 onto an imaging detector 26.
  • the imaging detec ⁇ tor 26 may be one or more CCD or CMOS sensors.
  • the sensors could be a 1 x M sensor, or a N x M area sensor or time delay integration (TDI) sensor.
  • the imaging detector 26 may comprise multiple area sensors, as described hereinbelow.
  • the imaging detector 26 is re ⁇ sponsive to the detected changes in intensity and operative to develop signals corresponding thereto.
  • Oscillatory or stepped motion of the light beam hitting the surface of the article 12 may be used to scan the article 12.
  • the stage 14 carrying the article 12 can be moved continuously relative to the beam directing subsystem 20 in a predetermined pattern of motion.
  • the stage 14 may move the article in steps of appropriate size relative to the beam directing subsystem 20 between image capture positions. In any case, a rela ⁇ tive displacement of the article 12 and the illuminating beam in a predetermined pattern of mo ⁇ tion is produced.
  • the system 10 may also include an autofocus device 28.
  • the system 10 as shown in Fig. 1 is configured for bright-field inspection of article 12, the principles of the present invention, as described hereinbelow, may similarly be used in dark-field inspection.
  • the light source 16 is controlled by a control system 30, which energizes the light source 16 to emit the beams in conjunction with the scanning of the stage 14.
  • the control system 30 is capable of varying the configuration and sensitivity of the imag ⁇ ing detector 26, and coordinating the operation of an image processor 32 as is described herein- below.
  • the output of the imaging detector 26 is linked to the image processor 32, optionally associated with a reference database 34. Results of the image processing are provided to the user on a display 36.
  • the collection beam contains information about the pattern on the article 12, and also provides information regarding any defects present in the article 12 and on its surface. De ⁇ fects or contaminants in the optical components may cause unpredicted signal nonuniformities, thus making it harder to distinguish the defects, and may thus allow some microscopic defects to remain undetected. Therefore, there is a need to distinguish such system imperfections from true defects of the article 12.
  • Fig. 2 is a flow diagram illustrating a method of multi-pass inspection of an article in accordance with a dis ⁇ closed embodiment of the invention.
  • Each region on the mask is scanned at least twice and im ⁇ aged in a detector, using an overlap, which is typically but not necessarily at least 50% between each two consecutive frames in the scan direction. Alternatively, more than one detector can be used. Advantages of other detection arrangements for producing images of the frames will be ⁇ come evident from the disclosure of other embodiments herein.
  • the method begins at initial step 38. This is a calibration stage in which pre-scan masking is accomplished.
  • Pre-scan masking refers to the identification of system blemishes, so that they may be masked out of subsequent inspection images. Blank images are acquired as a composite calibration frame, which is then masked according to system blemishes that are pre ⁇ sent.
  • system blemishes generically includes contamination and other defects of the illumination system, the collection optics, as well as defects in the detector, such as defective pixels, and defects in any electronics required by the system.
  • the calibration frame may be prepared using a blank article. It may be noted that system blemishes cannot be practi ⁇ cally eliminated despite application of meticulous manufacturing and cleaning techniques to the inspection apparatus.
  • Fig. 3 is an image of a calibration frame 40 pre ⁇ pared in accordance with a disclosed embodiment of the invention as it would appear, for exam ⁇ ple on the display 36 (Fig. 1).
  • Annuli 42, 44 are typical instances of optical artifacts that consti ⁇ tute one kind of system blemish.
  • step 46 an optimal frame overlap is chosen. This is typically at least 50% of the frame area, but could be less than 50%. The latter would be possible, for example, if only a few blemishes were present and were generally not aligned along the scanning direction.
  • System blemishes have substantially constant frame coordinates. That is, their coordinates are the same on all frame images.
  • Mask defects have constant reticle coordinates, but inconstant frame coordinates. Indeed, all regions that are included on both of two successive frames have different coordinates on the two frames. The difference between the coordinates on the two frames is referred to herein as a "frame displacement".
  • Step 46 is typically performed automatically. It may conveniently be performed offline, and thus can be accomplished by any processor, not necessarily the processor of the imaging system.
  • step 48 images of overlapping regions of the article are acquired according to the frame overlap that was chosen at step 46.
  • step 50 the images acquired in step 48 are analyzed. Defects are identified. Each reported defect is labeled as masked (M) if its original pixel location, as acquired by the detector, corresponds to a system blemish, and unmasked (U) if it does not. Corresponding reti ⁇ cle coordinates in consecutive frames, wherein at least one apparent defect was identified, are identified and "clustered" together as pairs, so that each cluster or pair represents a single defect.
  • M masked
  • U unmasked
  • M a defect is reported once, in a masked region.
  • Optional post-processing procedures use different detection parameters for each case, due to different levels of suspicion that the various cases represent genuine defects.
  • Whether the case UM is characterized as a defect, or simply flagged for re- evaluation is controlled by a governing policy, which could be region-dependent. For example, in some areas of the reticle, defects could be inconsequential, in which case no further action would be necessary. In other regions, defects could be intolerable, and it would then be neces ⁇ sary to determine whether an instance of the case UM was a false positive detection, or a true defect. This could be accomplished, for example, by rescanning with a different frame registra ⁇ tion on the article under inspection.
  • Decision step 52 is a determination whether such a pol ⁇ icy is in effect. [0078] If the determination at decision step 52 is negative, then control proceeds to final step 54. A report of the defects identified is generated for the user.
  • step 56 A redetection procedure is applied to defects that are detected twice, other than the case MM.
  • the article is reilluminated by repeating step 48.
  • This can be implemented using a detection algorithm, which combines information from the two sets of im ⁇ ages. For instance, two corresponding images may be placed in registration and averaged in or ⁇ der to reduce noise.
  • redetection can be implemented by reprocessing memorized data corresponding to the previously scanned images using different detection thresholds. This alternative is generally more efficient than reimaging the data.
  • redetec ⁇ tion may be implemented by applying sub-pixel registration and averaging, or other known su ⁇ per-resolution techniques.
  • many combinations of the above mentioned techniques may be used to implement the redetection stage. It has been found that redetection can improve the signal-to-noise ratio by 40% as compared with the signal-to-noise ratio when only step 48 is performed.
  • step 56 control proceeds to step 58, where the images are again analyzed. Step 58 is performed in the same manner as step 50. The details are not re ⁇ peated in the interest of brevity. Control then proceeds to final step 54, which has been described above.
  • Throughput of the system 10 could be increased by using two or more cameras hav ⁇ ing a common f ⁇ eld-of-view, with physical separation between the cameras provided by the use of beam splitters. Such a system would scan at a normal speed. This arrangement does not em ⁇ ploy double inspection as described above. It would eliminate image sensor defects from consid ⁇ eration, but other forms of system contamination would continue to produce false positive detec ⁇ tion, since their frame coordinates would be identical in both cameras.
  • Fig. 4 is a schematic diagram of beam directing optics 60, which are constructed and operative in accordance with a disclosed embodiment of the invention.
  • the beam directing optics 60 can be implemented in the beam directing subsystem 20 of the system 10 (Fig 1).
  • Three cameras (not shown) are disposed at locations 62, 64, 66 for use as the imaging detector 26 (Fig. 1).
  • respective fields of view 68, 70, 72 of the three cameras are non-overlapping, so that multiple images can be acquired si ⁇ multaneously.
  • the beam directing optics 60 are adapted to scan an article under inspection at a high throughput, using a high fluence, while preventing false positive detection resulting from contamination or other defects on the CCD and other optical surfaces of the system. Using in ⁇ spection apparatus that incorporates the beam directing optics 60, it is possible to conduct inspec ⁇ tion at high magnification without causing any damage to the inspected article.
  • a beam 74 is reflected or transmitted from an article and is collimated or focused by a suitable lens 76.
  • the beam 74 has representative rays 78, 80, 82, 84, 86, 88, 90.
  • An optical element 92 reflects a part of the original beam 74 that is represented by the rays 78, 80 into a beam 94. Another part of the beam 74, which is represented by rays 82, 84, 86 is transmitted through the optical element 92 to form a beam 96.
  • An Optical elements 98, 99 reflect a part of the original beam 74 that is represented by the rays 88, 90 into a beam 100.
  • the locations 62, 64, 66 are established such that the paths of the beams 96, 94, 100 are equal in length.
  • the transmission of light on each channel is kept as high as if only a single camera was used.
  • the optical elements 92, 98 may be constructed as a single unit, such that a central transparent area allows passage of the beam 96, and the beams 94, 100 are reflected by coated areas.
  • the overall instantaneous field of view 102 of the imaging system is increased, relative to any of the fields of view 68, 70, 72, each of which are a field of view of a single camera.
  • the field of view 102 is typically rectangular, with the ratio between the sides equal to the number of cameras. Other mir ⁇ ror configurations are possible. Alternatively, the overall field of view may be square.
  • This arrangement provides a fast scan mode of operation, in which each of the three cameras (not shown) images its own field of view in the article plane without overlapping. In this fast scan mode, scanning takes place at a maximal speed V ⁇ V 1 • N . Alternatively, the sys ⁇
  • V tem can be optimized for multi-pass inspection at speed V - V 1 - N /2 , where V is the actual
  • N is the number of cameras
  • Vi is the scanning speed that would be required for a single camera to scan the article 12 (Fig. 1) in a single pass with the same resolution.
  • Fig. 4 While provision in Fig. 4 is made for three cameras, this is merely exemplary.
  • the beam directing optics 60 may be modified by those skilled in the art to provide locations for a larger number of cameras, or for only two cameras.
  • Embodiments using more than three cameras may be configured for simultaneous scanning using different overlaps in the fields of view.
  • an instance of the case UM could resolve into a case UUM or a case U-M, (where the symbol "-" represents absence of a defect indication).
  • Embodiments using three or fewer cameras can also be configured to scan with different frame overlaps, but at the cost of decreased throughput. The information provided by such embodiments could thus be used to increase the accuracy of classification of these instances.
  • Fig. 5 is a schematic diagram of beam directing optics 104, which are constructed and operative in accordance with a disclosed embodiment of the invention.
  • the beam directing optics 104 may be implemented in the beam directing subsys ⁇ tem 20 (Fig. 1), and are useful for applications in which a focal range, or process window, is to be evaluated on an article 106 under inspection.
  • the beam directing optics 104 can be used, for example, in the inspection of phase shift masks.
  • the beam directing optics 104 include three cameras (not shown) at the locations 62, 64, 66, which are adjusted to have the same field of view during a given time frame. While pro ⁇ vision in Fig. 5 is mode for three cameras, this is merely exemplary. Applying the principles of the invention, the beam directing optics 104 may be modified by those skilled in the art to pro ⁇ vide locations for a larger or smaller number of cameras, which can modify the resolution at which the process window is evaluated.
  • the locations 62, 64, 66 are established such that the effective optical paths of the beams 96, 94, 100 are different in length. This may be accom ⁇ plished by moving the locations 62, 64, 66 along the optical axes of their respective beams 96, 108, 110 such that optical paths extending from the article 106 to the location 64, from the article 106 to the location 62, and from the article 106 to the location 66 all differ in length.
  • cam ⁇ eras (not shown) disposed at the locations 62, 64, 66 all have the same field of view on the article under inspection, but are placed in different defocus.
  • one camera is focused on the surface of the article 106, indicated as a focal plane 112.
  • Another camera is defocused slightly on a focal plane 114 above the surface of the article.
  • the third camera is defocused slightly on a focal plane 116 below the surface of the article 106.
  • a beam 118 is reflected or transmitted from the article 106 via a suitable objective lens 120, and strikes a 2:1 beam splitter 122.
  • One third of the beam 118 continues toward the location 62 as the beam 96.
  • Two thirds of the beam 118 form a beam 124.
  • the beam 124 is di ⁇ rected to a beam splitter 126, and divides equally into the beam 108 and the beam 110, which are directed to locations 64, 66, respectively.
  • the beams 96, 108, 110 arrive with equal fluence at the locations 62, 64, 66, respectively.
  • the beam directing optics 104 may be realized as a modification of the beam direct ⁇ ing optics 60 (Fig. 4) in which the beam splitters 122, 126 have been added, and the rays 78, 80, 88, 90 are blocked, for example with a shutter, so that the mirrors 92, 98 become nonfunctional. Alternatively, the mirrors 92, 98 may be moved out of the path of the beam 74.
  • Fig. 6 is a composite schematic diagram of beam directing optics 128, which is constructed and operative in accordance with a disclosed embodi ⁇ ment of the invention.
  • the system 128 can be implemented in the beam directing subsystem 20 (Fig. 1).
  • the configurations of the beam directing optics 60 (Fig. 4) and the beam directing optics 104 (Fig. 5) can be interchanged.
  • the beam splitters 122, 126 are simply moved from non-operating positions 130, 132 into operating positions 134, 136, respectively, and a portion of the beam 74 is blocked by moving a shutter 138 from an open position 140 to a closed position 142, so that the mirrors 92, 98 are not operative to reflect any portion of the beam 74.
  • the cameras (not shown) are all set to focus on different planes, as described above in the discussion of Fig. 4. These operations are reversed when it is desired to reassume the configuration of the beam directing optics 60 (Fig. 4), in which case the cameras (not shown) are set to focus on the plane of the surface of the article under inspection.
  • the scanning scheme used in the beam directing optics 104 or the beam directing optics 60 depends on the operational mode.
  • a fast mode of operation using pulsed laser light, may be used when the effect of contamination defects is negligible.
  • Fast mode scanning requires moving the article stage between the laser pulses by a distance corresponding to one camera field of view multiplied by a number of cam ⁇ eras.
  • Fig. 7, schematically illustrates a fast scanning mode of operation using three cameras, in accordance with a disclosed embodiment of the invention.
  • a N* n laser pulse occurs.
  • the cameras (not shown) have respective fields of view 146, 148, 150.
  • the scan has progressed along the scanning direction, shown as the horizontal axis in Fig. 7.
  • a N+l tn laser pulse occurs,
  • the cameras now have fields of view 154, 156, 158, which are displaced to the right with respect to the fields of view 146, 148, 150.
  • the fields of view 146, 148, 150, 154, 156, 158 are non-overlapping.
  • FIG. 8 schematically illustrates multi-pass scanning in accordance with a disclosed embodiment of the invention.
  • pulsed laser light is used as in the mode disclosed with re ⁇ spect to Fig. 1, pulsed laser light is used.
  • the article pattern, indicated by hatched areas, is repli ⁇ cated in each time interval in order to illustrate discrete changes in the camera fields of view with respect to time.
  • Defective pixels 160 and contaminated areas 162 are shown.
  • a NTM laser pulse occurs, and three cameras (not shown) have fields of view 166, 168,
  • a N+l" 1 laser pulse occurs, and the three cameras have fields of view 174, 176, 178.
  • the field of view 148 overlaps the field of view 174.
  • the field of view 150 overlaps the field of view 176.
  • the overlaps should be at least 50%. In this manner, there is always at least one frame in which every point in the pattern can be observed without coinciding with a system blemish.
  • multi-pass scanning has the advantages that a beam originating from a total field of view during a time interval passes through different optical paths and is imaged on different cameras.
  • the fluence with regard to each camera is essentially equated by maximizing the use of mirrors instead of beam splitters.
  • the inventive scheme permits switching to multi-focus inspection by minor focusing adjustments in the cameras.
  • the optical arrangements of Fig. 5 and Fig. 4 can be realized using commercially available optical elements.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

Pendant une inspection de masque ou de réticule, chaque zone est balayée au moins deux fois au moyen d'une superposition entre chaque paire de cadres consécutifs. La contamination du système et les imperfections de la caméra présentent des coordonnées de cadre approximativement constantes, les défauts du masque présentant des coordonnées de réticule constantes mais des coordonnées de cadre de balayage inconstantes. Les vrais défauts sont détectés à des coordonnées différentes dans des cadres consécutifs avec un déplacement intermédiaire connu.
PCT/US2005/015932 2004-07-19 2005-05-04 Double inspection de reticule ou de plaquette WO2006019446A2 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
PCT/US2004/023395 WO2005010510A1 (fr) 2003-07-21 2004-07-19 Double inspection sur reticule/plaquette
USPCT/US2004/023395 2004-07-19
US92332204A 2004-08-20 2004-08-20
US10/923,322 2004-08-20

Publications (2)

Publication Number Publication Date
WO2006019446A2 true WO2006019446A2 (fr) 2006-02-23
WO2006019446A3 WO2006019446A3 (fr) 2006-05-04

Family

ID=34969055

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2005/015932 WO2006019446A2 (fr) 2004-07-19 2005-05-04 Double inspection de reticule ou de plaquette

Country Status (1)

Country Link
WO (1) WO2006019446A2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7433033B2 (en) 2006-05-05 2008-10-07 Asml Netherlands B.V. Inspection method and apparatus using same
WO2010021748A1 (fr) * 2008-08-22 2010-02-25 Corning Incorporated Systèmes et procédés de détection de défauts dans des corps de filtre céramiques
US9128064B2 (en) 2012-05-29 2015-09-08 Kla-Tencor Corporation Super resolution inspection system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6081325A (en) * 1996-06-04 2000-06-27 Kla-Tencor Corporation Optical scanning system for surface inspection
US6122397A (en) * 1997-07-03 2000-09-19 Tri Path Imaging, Inc. Method and apparatus for maskless semiconductor and liquid crystal display inspection
WO2005010510A1 (fr) * 2003-07-21 2005-02-03 Applied Materials Israel, Ltd. Double inspection sur reticule/plaquette
WO2005026706A1 (fr) * 2003-09-04 2005-03-24 Applied Materials Israel, Ltd. Procede de controle d'articles multipasse hautement efficace

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6081325A (en) * 1996-06-04 2000-06-27 Kla-Tencor Corporation Optical scanning system for surface inspection
US6122397A (en) * 1997-07-03 2000-09-19 Tri Path Imaging, Inc. Method and apparatus for maskless semiconductor and liquid crystal display inspection
WO2005010510A1 (fr) * 2003-07-21 2005-02-03 Applied Materials Israel, Ltd. Double inspection sur reticule/plaquette
WO2005026706A1 (fr) * 2003-09-04 2005-03-24 Applied Materials Israel, Ltd. Procede de controle d'articles multipasse hautement efficace

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7433033B2 (en) 2006-05-05 2008-10-07 Asml Netherlands B.V. Inspection method and apparatus using same
WO2010021748A1 (fr) * 2008-08-22 2010-02-25 Corning Incorporated Systèmes et procédés de détection de défauts dans des corps de filtre céramiques
US8049878B2 (en) 2008-08-22 2011-11-01 Corning Incorporated Systems and methods for detecting defects in ceramic filter bodies
US9128064B2 (en) 2012-05-29 2015-09-08 Kla-Tencor Corporation Super resolution inspection system

Also Published As

Publication number Publication date
WO2006019446A3 (fr) 2006-05-04

Similar Documents

Publication Publication Date Title
US7355690B2 (en) Double inspection of reticle or wafer
US5917588A (en) Automated specimen inspection system for and method of distinguishing features or anomalies under either bright field or dark field illumination
JP5355294B2 (ja) オブジェクト表面上における粒子検出
US6809809B2 (en) Optical method and apparatus for inspecting large area planar objects
US6693664B2 (en) Method and system for fast on-line electro-optical detection of wafer defects
US10739275B2 (en) Simultaneous multi-directional laser wafer inspection
WO2010038533A1 (fr) Appareil et procédé pour examiner un défaut de surface d’un objet
US20050122508A1 (en) Method and apparatus for reviewing defects
US7508526B2 (en) Defect inspecting apparatus
KR102079420B1 (ko) 통합된 멀티 패스 검사
JPH02114154A (ja) 欠陥または異物の検査方法およびその装置
JPH10325711A (ja) 検査方法およびその装置並びに半導体基板の製造方法
US20080043313A1 (en) Spatial filter, a system and method for collecting light from an object
JP5847841B2 (ja) コヒーレンス低減のための方法及びシステム
JP2012002676A (ja) マスク欠陥検査装置およびマスク欠陥検査方法
JPS6352696B2 (fr)
JP4822103B2 (ja) 検査装置及び検査方法並びにパターン基板の製造方法
WO2006019446A2 (fr) Double inspection de reticule ou de plaquette
EP1439385A1 (fr) Procédé et appareil pour la détection électro-optique rapide et en ligne de défauts de tranches de semi-conducteur
US12050184B2 (en) Mask inspection method and mask inspection apparatus
JPH0979991A (ja) パターン検査装置、欠陥検査装置およびパターン検査方法
US7457454B1 (en) Detailed grey scale inspection method and apparatus
JPH06258235A (ja) 面検査装置
WO2021213813A1 (fr) Système de métrologie d'identification de contaminants, appareil lithographique et procédés associés
JP2012163422A (ja) 検査装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase in:

Ref country code: DE

122 Ep: pct application non-entry in european phase