Source: http://www.google.com/patents/US20090033924?ie=ISO-8859-1
Timestamp: 2014-03-17 21:48:28
Document Index: 719092887

Matched Legal Cases: ['Art 1', 'Art 2', 'Art 3', 'Art 4', 'Art 5', 'Art 6', 'Art 7', 'Art 8', 'Art 9', 'Art 10', 'Art 11', 'Arts 1', 'Arts 1', 'Arts 1', 'Arts 1', 'Arts 10', 'Arts 10']

Patent US20090033924 - Defects Inspecting Apparatus And Defects Inspecting Method - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsAn inspecting apparatus and method including first and second illuminating units for illuminating a surface of a specimen to be inspected with different incident angles and first and second detecting optical units arranged at different elevation angle directions to the surface of the specimen for detecting...http://www.google.com/patents/US20090033924?utm_source=gb-gplus-sharePatent US20090033924 - Defects Inspecting Apparatus And Defects Inspecting MethodAdvanced Patent SearchPublication numberUS20090033924 A1Publication typeApplicationApplication numberUS 12/192,578Publication dateFeb 5, 2009Filing dateAug 15, 2008Priority dateNov 27, 2002Also published asUS7417721, US7768634, US8013989, US8228495, US8508727, US20060124874, US20100259751, US20110310382, US20120262709, WO2004063734A1Publication number12192578, 192578, US 2009/0033924 A1, US 2009/033924 A1, US 20090033924 A1, US 20090033924A1, US 2009033924 A1, US 2009033924A1, US-A1-20090033924, US-A1-2009033924, US2009/0033924A1, US2009/033924A1, US20090033924 A1, US20090033924A1, US2009033924 A1, US2009033924A1InventorsSachio Uto, Minori Noguchi, Hidetoshi Nishiyama, Yoshimasa Ohshima, Akira Hamamatsu, Takahiro Jingu, Toshihiko Nakata, Masahiro WatanabeOriginal AssigneeSachio Uto, Minori Noguchi, Hidetoshi Nishiyama, Yoshimasa Ohshima, Akira Hamamatsu, Takahiro Jingu, Toshihiko Nakata, Masahiro WatanabeExport CitationBiBTeX, EndNote, RefManReferenced by (8), Classifications (11), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetDefects Inspecting Apparatus And Defects Inspecting MethodUS 20090033924 A1Abstract An inspecting apparatus and method including first and second illuminating units for illuminating a surface of a specimen to be inspected with different incident angles and first and second detecting optical units arranged at different elevation angle directions to the surface of the specimen for detecting images of the specimen illuminated by the first and second illuminating units.
a stage for mounting a specimen to be inspected and movable at least one direction; a first illuminating unit which illuminates a surface of the specimen with a first slit-like shaped polarized laser beam with a first incident angle to the surface of the specimen; a second illuminating unit which illuminates the surface of the specimen with a second slit-like shaped polarized laser beam with a second incident angle to the surface of the specimen which is an angle greater than the first incident angle; a first detecting optical unit installed in a first elevation angle direction to the surface of the specimen and having first image-forming optics and a first image sensor to detect a first image of the specimen illuminated by the first illuminating unit or a second image of the specimen illuminated by the second illuminating unit; a second detecting optical unit installed in a second elevation angle direction to the surface of the specimen which is an angle direction greater than the first elevation angle direction and having second image-forming optics and a second image sensor to detect a third image of the specimen illuminated by the first illuminating unit or a fourth image of the specimen illuminated by the second illuminating unit; and a processor which processes images detected by the first image sensor and the second image sensor to detect a defect on the specimen. 2. A defect inspecting apparatus according to claim 1, wherein the first illuminating unit illuminates the surface of the specimen with a first ultraviolet laser beam and the second illuminating unit illuminates the surface of the specimen with a second ultraviolet laser beam.
3. A defect inspecting apparatus according to claim 1, wherein the second image-forming optics of the second detecting optical unit includes a polarizing plate.
4. A defect inspecting apparatus according to claim 1, wherein the first image-forming optics of the first detecting optical unit includes a first spatial filter and the second image-forming optics of the second detecting optical unit include a second special filter.
5. A defect inspecting apparatus according to claim 1, wherein the first illuminating unit illuminates the specimen with the first slit-like shaped polarized laser beam in a longitudinal direction of the slit-like shaped polarized laser beam.
6. A defect inspecting apparatus according to claim 1, wherein the second detecting optical unit is installed in a perpendicular direction relative to the surface of the specimen.
7. A defect inspecting apparatus according to claim 1, wherein a magnitude of an image formed by the second image-forming optics of the second detecting optical unit is variable.
8. A defect inspecting apparatus according to claim 1, wherein the first image sensor of the first detecting optical unit and the second image sensor of the second detecting optical unit are linear image sensors.
9. A defect inspecting apparatus comprising:
a stage for mounting a specimen to be inspected and movable at least in one direction; an illuminating optical unit having a first illuminator which illuminates a surface of the specimen with a first slit-like shaped polarized laser beam with a first incident angle to the surface of the specimen, and a second illuminator which illuminates the surface of the specimen with a second slit-like shaped polarized laser beam with a second incident angle to the surface of the specimen which is an angle greater than the first incident angle; a detecting optical unit having first detection optics installed in a direction of a first elevation angle to the surface of the specimen to detect light from the specimen caused by the illuminations the illuminating optical unit and a second detection optics installed in a direction of a second elevation angle to the surface of the specimen to detect light from the specimen caused by the illumination by the illuminating optical unit; and a processor which processes images detected by the first detection optics and the second detection optics to detect defects on the specimen and classifies the detected defects into one of plural defect categories; wherein the first illuminator of said illuminating optical unit illuminates the specimen with the first slit-like shaped polarized ultraviolet laser beam in a longitudinal direction of the first slit-like shaped polarized ultraviolet laser beam, and first illuminator and said second illuminator illuminate the specimen at different times. 10. A defect inspecting apparatus according to claim 9, wherein the illuminating optical unit includes a laser light source to emit an ultraviolet laser beam, and a switching means for switching a path of the emitted ultraviolet laser beam between the first illuminator and the second illuminator.
11. A defect inspecting method, comprising the steps of:
illuminating a surface of a specimen with a first slit-like shaped polarized laser beam with a first incident angle relative to the surface of the specimen; detecting a first image of the specimen illuminated by the first slit-like shaped polarized laser beam with a first detecting optical unit installed in a first elevation angle direction to the surface of the specimen and detecting a second image of the specimen illuminated by the first slit-like shaped polarized laser bream with second detecting optical unit installed in a second elevation angle direction to the surface of the specimen which is an elevation angle greater than the first elevation angle; illuminating the surface of the specimen with a second slit-like shaped polarized laser beam with a second incident angle relative to the surface of the specimen which is an angle greater than the first incident angle; detecting a third image of the specimen illuminated by the second slit-like shaped polarized laser beam with the first detecting optical unit installed in the first elevation angle direction and a fourth image of the specimen illuminated by the second slit-like shaped polarized laser beam with the second detecting optical unit installed in the second elevation angle direction; and processing the detected first image, second image, third image and fourth image to detect defects on the specimen and classifying defects detected by the detection. 12. A defect inspecting method according to claim 11, wherein the first detecting optical unit and the second detecting optical unit each include a spatial filter, and the first image, the second image, the third image and the fourth image are detected after passing through the spatial filter.
13. A defect inspecting method according to claim 11, wherein the first slit-like shaped polarized laser beam is incident to the surface of the specimen from a longitudinal direction of the slit-like shaped polarized laser beam.
14. A defect inspecting method according to claim 11, wherein the second detecting optical unit detects the second image and third image from a perpendicular direction to the surface of the specimen.
15. A defect inspecting method according to claim 11, wherein a magnitude of an image formed by image-forming optics of the second detecting optical unit is variable.
16. A defect inspecting method according to claim 11, wherein the first detecting optical unit and the second image sensor of said second detecting optical unit include linear image sensors. Description
CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. application Ser. No. 10/536,715, filed May 27, 2005, the contents of which are incorporated herein by reference.
As one of such technologies relating to the conventional arts, for detecting the foreign matters on the semiconductor substrate, for example, in Japanese Patent Laying-Open No. Sho 62-89336 (1987)<Conventional Art 1>, there is disclosed a technology of detecting lights scattered from foreign matters while irradiating a laser beam thereupon, being generated in a case when the foreign matters adhere upon the semiconductor substrate, and then making comparison thereof, with using the results of inspection obtained previously, upon the same king of semiconductor substrate, so as to neglect a false report due to the patterns thereon; thereby, enabling an inspection of foreign matters and defects with high sensitivity and high reliability. Also, as is disclosed in Japanese Patent Laying-Open No. Sho 63-135848 (1988)< Conventional Art 2>, for example, there is also known a technology of detecting lights scattered from foreign matters while irradiating a laser beam thereupon, being generated in a case when the foreign matters adhere upon the surface of semiconductor substrate, and then analysis is made upon the foreign matter detected, through the analyzing technology, such as, the laser photoluminescence or the secondary X-ray analysis (XMR), etc.
Also, as a technology for inspecting the above-mentioned foreign matters, there is disclosed a method of removing the lights emitted from repetitive patterns upon a wafer when irradiating coherent lights upon the wafer through a space filter(s), thereby detecting the foreign matters and/or defects having no such repetitiveness, with emphasis thereof. Further, a foreign matter inspecting apparatus is also already known, for example, in Japanese Patent Laying-Open No. Hei 1-117024 (1989)<Conventional Art 3>, in which apparatus a light is irradiated upon circuit patterns formed on a wafer from a direction inclined by 45 degree with respect to a group of main lines of the said circuit patterns, thereby preventing the 0th-order diffracted light from entering into an opening of an objection lens. Moreover, as the conventional technologies relating to a defects inspecting apparatus and a method thereof, for inspecting foreign matters, etc., there are also already known the followings: Japanese Patent Laying-open No. Hei 1-250847 (1989)<Conventional Art 4>; Japanese Patent Laying-Open No. Hei 6-258239 (1994)<Conventional Art 5>; Japanese Patent Laying-Open No. Hei 6-324003 (1994)<Conventional Art 6>; Japanese Patent Laying-Open No. Hei 8-210989 (1996)<Conventional Art 7>; Japanese Patent Laying-Open No. Hei 8-271437 (1996)<Conventional Art 8>; and Japanese Patent Laying-Open No. 2000-105203 (2000)<Conventional Art 9>. In particular, the conventional technology 9 describes that a size of detecting pixel can be changed through exchanging a detection optic system. Also a technology for measuring a size of foreign matter is disclosed in Japanese Patent Laying-Open No. 2001-60607 (2001)<Conventional Art 10> and Japanese Patent Laying-Open No. 2001-264264 (2001)<Conventional Art 11>, for example.
DISCLOSURE OF THE INVENTION However, with the Conventional Arts 1 through 9, it is impossible to detect the fine or microscopic foreign matters, or defects upon the substrate, easily, on which repetitive patterns and non-repetitive patterns are formed mixing with each other, at high sensitivity and at high-speed. Thus, with those Conventional Arts 1 through 9 mentioned above, in particular, in a portion other than the repetitive portion, such as, a cell portion of a memory, for example, there is a problem that the detection sensitivity is low (i.e., the minimum size of a detectable foreign matter is large). Also, with the Conventional Arts 1 through 9 mentioned above, there is other problem that the detection sensitivity is low on the fine foreign matters or defects, such as, a level of 0.1 μm, in particular, within a region where the pattern density is high. Further, with the Conventional Arts 1 through 9 mentioned above, there is other problem that the detection sensitivity is also low, in particular, on the foreign matters or defects, which build up short-circuiting between the wiring patterns, or on a film-like defects. Or, with the Conventional Arts 10 and 11 mentioned above, there is a problem that accuracy is low, in particular, when measuring the foreign matters or the defects. Also, with the Conventional Arts 10 and 11 mentioned above, there is another problem that the sensitivity is low when detecting the foreign matters upon the wafer surface, on which a transparent thin film is formed.
First, explanation will be made on a method of changing the illumination direction φ. FIGS. 2( b) and FIG. 3 are plane views; in particular, in the case where four (4) sets of the illumination optic systems 10 are constructed by using only one (1) lager light-source 11. A branching optical element 218, being built up with a mirror, a prism, and so on, transmits the laser light L0 emitted from the laser light-source therethrough, or reflects it thereupon, thereby to guide it into three (3) directions, through movement in the position thereof in the Y direction. A first laser light L1 penetrating through the branching optical element 218 is separated into a penetrating light and a reflected light through a branching optical element 221, such as, a half prism or the like (for example, a polarization beam splitter), wherein from the light penetrating therethrough can be obtained the illumination light beam 230, having the inclination angle of α and the direction inclined by φ from the Y axis, by reflecting it upon the mirror 235, again, via a mirror 231, an optic system 232 for adjusting the beam diameter, a mirror 233 and the conical surface lens 234 shown in FIG. 4( a), while from the light reflected upon the other branching optical system 221 can be obtained the illumination light beam 220, having the inclination angle of α and the direction inclined by φ from the Y axis, by reflecting it upon the mirror 225, again, via an optic system 222 for adjusting the beam diameter, a mirror 223 and the conical surface lens 224 shown in FIG. 4( a). However, the beam-diameter adjusting optical systems 222 and 232 are provided for adjusting the beam diameters of the laser beams, which are incident upon the conical surface lenses 224 and 234, so that the slit-like beam 201 can be obtained being equal in the size, which is irradiated upon the wafer 1. Also with provision of a mirror 260 in the place of the half-prism, as being the branching optic element 221, it is possible to obtain an illumination from one side. Also, with insertion of wave plates (e.g., λ/2 plates) 226 and 236 behind the branching optic element (for example, the polarization beam splitter) 221, it enables to align the polarization direction of the laser lights to be irradiated thereupon.
In particular, according to the present invention, as will be mentioned later by referring to FIG. 6, the illumination is made at the inclination angle γ from the longitudinal direction (i.e., the Y direction) of the slit-like beam 201, by means of the illumination light beam 250 upon basis of the third laser beam L3, as was mentioned above, so as to detect fine or microscopic foreign matters and/or scratches on a transparent film (such as, an oxidation file) 800, upon which the CMP (Chemical Mechanical Polishing) process is treated, from an oblique direction (o intersecting the Y direction, so as to lesson receiving of the ill influences due to the lights scattered from background patterns 801. With this inclination angle γ of the illumination light beam 250, it is preferable to be set from 5 degree to 10 degree, approximately, at an angle relatively low, from a viewpoint of detection of the fine foreign matters and/or scratches or the like, on the oxidation film 800. By the way, when using a cylindrical lens 255 having a uniform focal distance therein, the slit-like beam 201 comes to be drum-like, being narrowed in width at a center thereof. However, it is possible to obtain the slit-like beam, not being narrowed at the center, by exchanging the focal distances of the cylindrical lens 255, so as to be fit to the inclination angle γ.
The present inspecting apparatus has such a function of conducting the defect inspection at a high speed, and also of conducting the inspection with high sensitivity, but at a low speed. Namely, the inspection can be executed with high sensitivity upon an inspection target or an area where the circuit patters are manufactured at high density, since an image signal of high resolution can be obtained with increasing up the magnification of the detection optic system. Also, the high-speed inspection can be achieved by lowering the magnification down, upon an inspection target or an area where the circuit patters are manufactured at low density, while keeping the high sensitivity.
With this, it is possible to optimize the sizes of the foreign matters to be detected, as well as, the size of the detecting pixels; thereby bringing about an effect of eliminating noises other than is those from the foreign matters, so as to detect only the lights scattered from the foreign matters, with high efficiency. Namely, with the present inspection apparatus, the magnification of the detection optic system 200 provided above the wafer 1 can be changed with simple structure thereof.
Next, explanation will be made on the optical filter group 24. The ND filter 24 a is for use of adjusting an amount of lights detected upon the photo-detector 26, and then the photo-detector 26 turns into the saturated state when receiving the reflected lights of high brightness thereupon; therefore, it cannot detect the foreign matters with stability. This ND filter 24 a is not always necessary when an amount of irradiation lights can be adjusted within the illumination optic system 10; however, with using the ND filter 24 a therein, it is possible to enlarge an adjustable range on an amount of detection lights; thereby enabling an adjustment on the light amount to be the most suitable for various inspection targets. For example, an output can be adjusted from up to 100 W with using the laser light source 1, and if preparing a filter of 100% penetration and a filter of 1% penetration, as the ND filter 24 a, the light amount can be adjusted from 10 mW up to 100 W; therefore, it is possible to adjust the light amount, widely.
Then, according to the present invention, as was mentioned above, the laser beam L3, which is enlarged on the beam diameter thereof, is irradiated upon the surface of the wafer 1 through the cylindrical lens 255, at the low illumination angle γ (approximately, from 5 degree up to 10 degree, for example), in the form of the illumination light beam 250, as shown in FIG. 11, and thereby forming the slit-like beam 201 having the longitudinal direction directed into the Y direction. However, as is shown in FIGS. 1 and 2( b), it is preferable to provide the cylindrical lens 225 in front of the mirror 256 on the optical path of the illumination light. And, the side-directed detection optic system 600 is disposed, with respect to the illumination light beam 250 generated from the fine foreign matters and/or the scratches or the like 802, lying on the transparent film 800 formed on the surface of the wafer 1, in such manner that it can detects mainly the side-directed scattered lights thereof at a low angle. For that purpose, that side-directed detection optic system 600 comprises an image-forming optic system 630 and a photo-detector 640, each having an optical axis inclined by the low detection-angle θ (from 5 degree to 10 degree, approximately) from the direction intersecting the Y direction by an angle ω (for example, from 80 degree to 100 degree, approximately). Then, setup of the intersection angle ω in the vicinity of 90 degree brings the light-receiving surface of the photo-detector 640 to have a relationship of forming an image through the image-forming optic system 630, with respect to the slit-like beam 201, and it further allows setup of a magnifying power of image-forming within the image-forming optic system 630, so that the light-receiving surface of the photo-detector 640 can front on the entire illumination area or region of the slit-like beam 201. By bringing the side-directed detection optic system 600 into the relationship of forming such the image, at the low angle with respect to the slit-like beam 201, in this manner, it is possible to prevent ill influences of lights straying from other than the slit-like beam area; therefore, enabling parallel processing thereof, in the similar manner to the magnification-variable detection optic system 20, and obtaining high-speed of the inspection. Further, the photo-detector 640 can be built up with the TDI sensor or the photo-multiplier tubes, etc., in the similar manner to the photo-detector 26.
Next, explanation will be given about the details of the signal processing system 40 for processing outputs from the photo-detectors 26 and 640, etc., by referring to FIG. 14. The signal processing system 40 comprises; an A/D converter 1301 for converting the signal, which is inputted from each of the photo-detectors 26 and 640, being exchanged therebtween; a data memory portion 1302 for memorizing detected image signal f(i,j) on which A/D conversion is made; a threshold value calculation processor portion 1303 for processing calculation of a threshold value upon basis of the detected image signal mentioned above; foreign-matter detection processor portions 1304 a-1304 n, each for conducting a foreign-matter detection process for each of pixel merges, upon basis of the detected image signal 510 obtained from the data memory portion 1302 mentioned above and the threshold value image signals (Th(H), Th(Hm), Th(Lm), Th(L)) obtained from the threshold value calculation processor portion 1303; a characteristic-quantity calculator circuit 1310 for calculating out characteristic quantities, such as, an amount of scattering lights obtained from defect detection through the low-angle illumination/the upper-directed detection (i.e., the low-angle illumination by means of the illumination light beams 220 and 230/the upper-directed detection by means of the photo-detector 200), an amount of the scattered lights obtained from defect detection through the high-angle illumination (including a middle-angle illumination)/the upper-directed detection (i.e., the high-angle illumination by means of the illumination light beams 220, 230 and 240/the upper-directed detection by means of the detection optic system 200), an amount of the scattered lights obtained from defect detection through the low-angle illumination/the oblique detection (i.e., the low-angle illumination by means of illumination light beam 250/the oblique detection by means of the side-directed detection optic system 600), and the detected number pixels indicative of an extent of the defects, etc., for example; an integrated processor circuit 1309 for classifying the defects, such as, small/large foreign matters or pattern defects or micro-scratches, etc., on the semiconductor wafer, into each kinds of those defects, upon basis of the characteristic quantity of each of the merges, which can be obtained from the said characteristic-quantity calculator circuit 1310; and a result display portion 1311. The foreign-matter detection processor 1304 a-1304 n are constructed with, each comprising pixel merge circuit portions 1305 a-1305 n, 1306 a-1306 n, foreign-matter detection processor circuits 1307 a-1307 n, and inspection area processor portions 1308 a-1308 n, corresponding to each of merge operators of, for example, 1�1, 3�3, 5�5, . . . n�n.
However, the threshold-value calculation processor portion 1303 is described in Japanese Patent Laying-Open No. 2000-105203 (2000). Thus, within the threshold-value calculation processor portion 1303, threshold-value image of the detection threshold values (i.e., Th(H) and Th(L)) and verification threshold values (i.e., Th(Hm) and Th(Lm)) is calculated out from the following equation (2). Where, a deviation of input data can be calculated out by (σ(ΔS)=√{square root over ( )}(ΣΔS2/n−ΣΔS/n)), and an averaged value of the input data by (μ(ΔS)=ΣΔS/n)). Further, it is assumed that a coefficient (i.e., the magnification) is �k� for setting up the threshold value corresponding to a number �n� of the input data, and that a coefficient is �m� (assuming that �m� is smaller than 1) for verification.
Next, explanation will be give about the pixel merge circuit portions 1305 and 1306 for signals, by referring to FIGS. 15 and 16. The merge circuit portions 1305 a-1305 n and 1306 a-1306 n are constructed with merge operators 1504, each being different from each other. Each of the merge operators 1504 has a function of combining the detected image signal f (i,j), which can be obtained from the data memory portion 1302, and the threshold-value image signal 520, which can be obtained from the threshold-value calculation processor portion 1303, including the verification threshold-value images Th(H), Th(L), Th(Hm) and Th(Lm) within a region of n�n pixels for each, and it is a circuit for outputting an averaged value of n�n pixels, for example. Herein, the pixel merge circuit portion 1305 a or 1306 a is made up with the merge operator for merging 1�1 pixel, the pixel merge circuit portion 1305 b or 1306 b with the merge operator for merging 3�3 pixels, the pixel merge circuit portion 1305 c or 1306 c with the merge operator for merging 5�5 pixels, . . . and the pixel merge circuit portion 1305 n or 1306 n with the merge operator for merging n�n pixels, for example. Thus, the merge operator for merging 1�1 pixel provides the input signal 510 or 520 as it is, to be an output therefrom.
With the threshold image signals, since each one is made up with four (4) image signals (i.e., Th(H), Th(L), Th(Hm) and Th(Lm)), there is necessity of providing four (4) pieces of the merge operators Op in each of the pixel merge circuit portions 1305 a-1306 n. Accordingly, from each of those pixel-merge circuit portions 1305 a-1306 n are outputted the detection image signals, being treated with merge processing in the various kinds of merge operators 1504, in the form of merge-process detection image signals 431 a-431 n. On the other hand, from each of those pixel-merge circuit portions 1306 a-1306 n are outputted four (4) threshold image signals (Th(H), Th(Hm), Th(Lm) and Th(L)), being treated with the merge process thereon within the various kinds of merge operators Op1-Opn, in the form of merge-processed threshold-value image signals 441 a(441 a 1-441 a 4)-441 n(441 n 1-441 n 4). However, the merge operator within each of the pixel-merge circuit portions 1306 a-1306 n is same to one another.
And, the foreign-matter detection processor circuits 1307 a-1307 n are constructed with comparators 1601 a-1601 n for comparing the levels of merge-process difference signals 471 a-471 n and merge-process threshold signals 441 a-441 n, respectively, and detect-position determination processor portions 1602 a-1602 n for identifying detecting points or positions of the foreign matters. In the comparator circuits 1601 a-1601 n are provided delay memories 451 a-451 n for delaying the detected image signals, which are obtained from the pixel merge circuits 1305 a-1305 n and are treated with the pixel merge thereupon, for repetition formed, such as, on a chip, for example, and difference processor circuits 461 a-461 n for forming difference signals between the detected image signals 431 a-431 n and reference image signals, which are delayed through the delay memories mentioned above and are treated with the pixel merge thereupon. Accordingly, the comparator circuits 1601 a-1601 n are those for making comparison with the merge-process threshold value image Th(H) (i,j), Th(Hm) (i,j), Th(Lm) (i,j) and Th(L) (i,j), which are obtained from four (4) pieces of the pixel merge circuits Op of each of the pixel merge circuit portions 1306 a-1306 n, and have a function of determining the foreign matters, if the merge-process difference detection signals 471 a-471 n are larger than the merge-process threshold value image Th(i,j), for example.
In the present embodiment, there are prepared four (4) kinds of the threshold values, thereby conducting the determination process upon merge-process threshold value images 1603, 1604, 1605 and 1606, for each of the merge operators, within the comparator circuits 1601 a-1601 n. Next, explanation will be made about the detect-position determination processor portions 1602 a-1602 n. The process of detection-position determination is that for identifying the chip, on which the foreign matters or the defects lies thereon, corresponding to the various kinds of merge operators, thereby calculating out the positional coordinates (i,j). The way of thinking of the present process is to identify the chip, on which the foreign matters or the defects are detected, by using the results detected through the detection threshold values (i.e., Th (H) and Th(L)) and the verification threshold values (i.e., Th(Hm) and Th(Lm)), which are the threshold values smaller than the said detection threshold values in the value thereof.
First of all, explanation will be made on the characteristic-quantity calculator circuit 1310. This characteristic quantity means a value, indicative of the feature or characteristics of the detected foreign matters and/or defects, and the characteristic-quantity calculator circuit 1310 is a processor circuit for calculating out the characteristic quantity mentioned above. As the characteristic quantity, there can be listed up, for example, an amount of lights reflected and/or diffracted upon the foreign matters and/or defects (i.e., an amount of scattered lights) (Dh and D1), which are obtained through the high-angle illumination/the upper-directed detection, the low-angle illumination/the upper-directed detection, and the low-angle illumination/the oblique detection, the number of detecting pixels, the configuration of the foreign-matter detecting area and the direction of an inertia main axis thereof, the detecting position of foreign matters on the wafer, the kinds of circuit patterns on the background, and the threshold values when detecting the foreign matters, etc.
Next, explanation will be made about another embodiment of method for calculating out the detected light amount D. The way of thinking in the present embodiment lies in that, the saturated portion of the foreign matter signal portion 2602 shown in FIG. 19( b) is compensated with an aid of approximation of the Gauss distribution; thereby, obtaining an improvement of accuracy of calculation of the detected light amount. About this compensation will be made explanation, by referring to FIG. 20. This FIG. 20 is a view for presenting the Gauss distribution in the three dimensional (3D) manner. This FIG. 20 shows the case where the signal is saturated at y=y0, and a method that will be explained hereinafter, about calculating out the detected light amount of the entire Gauss distribution, in the portion below y=y0 shown in FIG. 20; i.e., in the case where the detection light amount can be obtained in a portion of V3. First of all, it is assumed that a volume of the entire Gauss distribution shown in FIG. 20 is V1, that of portion above y=y0 V2, and that of portion below y=y0 V3, respectively. It is also assumed that the cross-section configuration can be obtained from the following equation (4) on the x-axis of the Gauss distribution shown in FIG. 20:
V 1=2�π�σ2 (5)
CC=V 1/(V 1 −V 2) (7)
CC=1/(y 0�(1−log(y 0))) (8)
y 0=exp(−SW 2/2/σ2) (9)
CC=exp(SW 2/2/σ2)/(1+SW 2/2/σ2) (10)
Further, explanation will be made about the method for classifying the foreign matters from the foreign-matter information considered to be the same thing, by referring to FIGS. 22( a) and 22(b). In FIG. 22( a), onto the horizontal axis thereof is set the scattered light amount (D1) obtained by the first inspection mentioned above (i.e., the low-angle illumination), while onto the vertical axis the characteristic quantity, i.e., the scattered light amount (Dh) obtained by the second inspection (i.e., the high-angle illumination). In FIG. 22( b), onto the horizontal axis thereof is set the scattered light amount (D1′) obtained from the side-directed detection optic system 600 under the low-angle illumination, while onto the vertical axis is set the scattered light amount (Dh′) obtained therefrom under the high-angle illumination. In those FIGS. 22( a) and 22(b), a reference numeral 3501 depicts points, being plotted corresponding to each of the characteristic quantities of the foreign matters, which are considered to be the same thing. In the present embodiment, one (1) point indicates one (1) piece of foreign matter. Also, a reference numeral 3502 depicts a classification curve for classifying the foreign matters detected during the inspection. Those FIGS. 22( a) and 22(b) show a case of dividing into two (2) areas by the classification line, i.e., an area 3503 and an area 3504. As a method for classifying, if the above-mentioned foreign matters detected should be plotted within the area 3503 in FIG. 22( a), they are classified to be �large foreign matters or scratches�, while they are classified to be �small foreign matters� if they should be plotted within the area 3504. Also, detected things 4510 are classified to be the defects within film, lying inside the transparent film 800, if the scattered light amount (D1′) within the side-directed detection optic system 600 is smaller, comparing to the scattered light amount (D1) under the low-angle illumination and the scattered light amount (Dh) under the high-angle illumination, as is shown in FIG. 22( a). By the way, in the case of an upper-directed detection under the low-angle illumination, the brightness comes down due to spreading of the illumination light beam upon the wafer, thereby lowering the sensitivity; therefore, the detection sensitivity of the upper-directed detection is lower than that of the side-directed detection.
Herein, it is necessary to determine the classification line 3502, in advance. As a method for determining it in advance, plotting the detected things in several numbers thereof on a graph of FIGS. 22( a) and 22(b), which are already known to be the large foreign matters or the small foreign matters in advance, the classification line 3502 is set up, so that the detected things can be divided, correctly. Or, calculating out the characteristic quantity obtainable from the foreign matters, through simulation thereon, the classification line 3502 may be set up from the result thereof. Herein, as a method of affirming the kinds of foreign matters, for example, the classification may be made with using the detected things upon the wafer, which are already known about the defects coordinate and the kinds thereof through a review apparatus, such as, an observatory optic microscope 60 or a SEM, etc., which is mounted within the inspecting apparatus. With the review apparatus, including the observatory optic microscope 60 mounted within the inspecting apparatus, it is possible to make the classification within a short time, while in the case of using the SEM, it is possible to make the classification with high resolution. The detected things are the foreign matters, the scratches, or the foreign matters within transparent film, etc., in the kind thereof. Upon setup of the classification line 3501, the threshold value may be set at such a certain value of the scattered light amount obtainable under the low-angle illumination, that there occurs no error of detecting electric noises within the detector 26 to be the foreign matters. Also, firstly calculation is made upon a position of the center of gravity, for each of the groups of large foreign matters and small foreign matters, thereby obtaining the standard deviation at each of the plotted points therefrom. Next, an orthogonal bisector is drawn, as the classification line 3502, at a point on a straight line, satisfying Lx(r1/r1+r2)), where distance is �L� of a line joining between the respective positions of the center of gravity, and radii of the standard deviation from the respective positions of the center of gravity are �r1� and �r2�, respectively.
The way of thinking of this classifying method will be explained by referring to FIG. 24. This FIG. 24 shows a characteristic quantity space, in which the three (3) kinds of characteristic quantities are set up to the three (3) axes thereof. As those three (3) axes, for example, a characteristic quantity 1 is the characteristic quantity (for example, the scattered light amount (Dh)) obtained from defects under the first optical condition (for example, the high-angle illumination), the second characteristic quantity 2 is the characteristic quantity (for example, the scattered light amount (D1)) obtained from defects under the second optical condition (for example, the low-angle illumination), and a third characteristic quantity is the characteristic quantity (for example, the detecting pixel number: a flat area of the defects) obtained from defects under the third optical condition (for example, the high-angle illumination of being the first optical condition and the low-angle illumination of being the second optical condition). In such the characteristic space, (number of classification categories�1) pieces of classification boundaries are set up. Since this FIG. 24 shows an example of conducting the classification into three (3) kinds from three (3) kinds of characteristic quantities, therefore it is sufficient to set up the classification boundaries in the number of two (2) or more than that.
In particular, as those three (3) kinds of characteristic quantities, if setting up the scattered light amount (i.e., the detection light amount) (Dh) from defects under the high-angle illumination, the scattered light amount (i.e., the detected light amount) (D1) from defects under the low-angle illumination, and the detecting pixel numbers of defects under the high-angle illumination and the low-angle illumination, it is possible to classify the defects, at least, into three (3) kinds of categories (the foreign-matter defects, the scratch defects, and the circuit-pattern defects, for example). Further, since the detecting pixel number of defects (i.e., the flat area of defects) are taken or memorized as one of the characteristic quantities, therefore, it is also possible to classify the category of the foreign-matter defects into the large foreign matters and the small foreign matters, as shown in FIG. 22.
Then, FIG. 24 shows the example of setting up the classification boundaries 4501 and 4502. As a method for classification, firstly the three (3) characteristic quantities mentioned above are plotted within the characteristic quantity space shown in FIG. 24 (S245 sown in FIG. 23). Then, the foreign matters belonging to the area or region divided by the classification boundaries 4501 and 4502 are classified into the category �a� (for example, the foreign-matter defects), the category �b� (for example, the scratch defects), and the category �c� (for example, the circuit-pattern defects), for example (S246 shown in FIG. 23). This FIG. 24 shows the example of classifying about thirty (30) pieces of defects into the category �a�, the category �b� and the category �c�, while changing the display marks thereof, for each of the defects classified into the respective categories. Thus, those classified into the category �a� (for example, the foreign-matter defects) is displayed by �◯�, those classified into the category �b� (for example, the scratch defects) by �▴�, and those classified into the category �c� (for example, the circuit-pattern defects) by �x�, respectively.
As a method for setting up the classification boundaries, firstly into the characteristic quantity spaces 4601, 4602 and 4603 are plotted the characteristic quantities of the foreign matters, the classification categories of which are already known. Herein, when making plots into the characteristic quantity spaces, the difference in the category is also presented, by changing the display mark or the like, for each of the categories thereof. For example, FIGS. 25( a) through 25(c) show examples, each displays the category �a� by �0�, the category �b� by �A�, and the category �c� by �x�, respectively.
Next, within those characteristic quantity spaces 4601, 4602 and 4603, the classification boundaries 4604, 4605 and 4606 are established at the position, so as to enable to divide the categories, for each. Herein, if the categories overlap in plural number thereof, there is no necessity of establishing the classification boundary between them. For example, since the category �a� is distributed at the position separated from other categories �b� and �a� within the characteristic quantity space 4601, then the classification boundary 4604 should be established for classifying the category �a� separated from the categories �b� and �a�; however, since the categories �b� and �c� overlap with each other in the distribution thereof, there is not always necessity of establishing the classification boundary between them. When conducting the classification upon the foreign matters, they are classified into the category �a� or the others, by using this characteristic quantity space 4601. In the similar manner, within the characteristic quantity spaces 4602 and 4603 are established the classification boundaries 4605 and 4606, respectively, thereby to be used when conducting the classification upon the foreign matters.
FIG. 29 shows an example of displaying the detected things, being classified into the foreign matters and the scratches, as well as, a rate or ratio of correctness of classification. This display shown in FIG. 29 comprises, detection numbers 4001 for each of the categories classified, an inspection map 4002 for showing the detecting portion of the detected things, and a confirmation screen 4003 of the detected things. The confirmation screen 4003 of the detected things, further, comprises a confirmation screen portion 4004 of the detected things, which are classified into the foreign matters by means of the defects inspecting apparatus according to the present invention, a confirmation screen portion 4005 of the detected things, which are classified into the scratches, and a classifying correctness rate display portion 4006. Those confirmation screen portions 4004 and 4005, further, comprise an observatory screen 4007 of the detected things and also a classifying-correctness determining portion 4008.
Next, the inspection condition setup (S214) means selection on the direction and the angle of illumination lights irradiated upon the wafer, and/or selection on the magnifying power of the magnification-variable detection optic system 20, for the total controller 50 to make control upon the illumination optic system 10 and the magnification-variable detection optic system 20. As a selecting method, for example, the setup can be achieved by using an optical condition setup window as shown in FIG. 31, for example.
The said optical condition setup screen comprises an illumination direction condition 3001 for the illumination system, an illumination angle condition 3002 for the illumination system, and a detection optic system condition 3003 (including the detection direction, such as, the upper-directed one or the oblique one, for example). In this FIG. 31 is shown an example, on which the selection can be made among three (3) kinds on the illumination direction condition 3001, three (3) kinds on the illumination angle condition 3002, and between two (2) kinds on the detection optic system condition 3003. A user of the present defects inspecting apparatus can make selection of the optimal condition while watching the contents of the conditions 3001, 3002 and 3003, appropriately. For example, when she/he wishes to make an inspection on the foreign matters on the surface thereof at high sensitivity, if the inspection target 1 is a wafer during a metal-film deposition process, then it is enough to select �deposition process� from conditions within the illumination direction condition 3001, further select �surface foreign matters� from conditions within the illumination angle condition 3002, and select �upper-directed detection (magnification-variable): high sensitivity inspection� from conditions within detection optic system condition 3003; and an example of conducting those selections is shown in FIG. 31. Also, when she/he wishes to make an inspection upon the defects, such as, the foreign matters and/or the scratches, if the inspection target is the oxidation film, for example, then it is enough to select �CMP post-process� from conditions within the illumination direction condition 3001, and further select �surface foreign matters� from conditions within the illumination angle condition 3002, and select �oblique detection: high speed inspection� from conditions within detection optic system condition 3003.
Next, the optical filter setup (S215) is for setting up the space filter 22 shown in FIG. 1 and/or the optical filter 24 b, such as, of a polarizing element or the like, for the total controller portion 50 to make control upon the detection optic system 200, etc. This space filter 22 is one for shielding the lights reflected and/or diffracted from the repetitive patterns manufacture on the wafer; therefore, it is preferable to be set up for the wafer having the repetitive patterns, but no necessity to be set up for the wafer having no such repetitive pattern thereon. Also, the polarizing element 24 b is effective if it is used in the situation where edges of wiring patters are etched in vicinity of a right angle, for example.
Also, the setout-contents display change button 4303 is that for making change or customizing the display items. For example, when there is an item, on which the user always wishes to establish, or with which she/he wishes to increase the number of setting contents, this setout-contents display change button 4303 enables the user to make such changes thereupon; therefore, the user can obtain an easy screen to use, to establish the inspection conditions, as quickly as possible. Further, the help button 4304 is for letting information to be outputted, for the purpose of aiding the user when she/he looses the way of setting and/or cannot understand the contents of setting. As a method thereof, the contents of the each setup item may be announced in the form of voice guidance, or an operation method may be displayed through the moving picture of MPEG, etc. Or, it is also possible for the user to talk with a designer of a maker, who produces the foreign-matter inspecting apparatus according to the present invention, on line, via a network or a telephone circuit.
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to make an inspection of defects, such as, fine or microscopic foreign matters and/or scratches, etc., of a level of 0.1 μm, upon an inspection target substrate, upon the surface of which is formed a transparent film, such as, oxidation films, etc., and/or an inspection target substrate, on the surface of which repetitive patterns are mixed up with non-repetitive patterns, at high sensitivity and high seed.
Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7719669 *Jul 12, 2007May 18, 2010Hitachi High-Technologies CorporationSurface inspection method and surface inspection apparatusUS7916287Apr 6, 2010Mar 29, 2011Hitachi High-Technologies CorporationSurface inspection method and surface inspection apparatusUS8107065Jul 6, 2010Jan 31, 2012Hitachi High-Technologies CorporationMethod and apparatus for detecting defectsUS8285025 *Mar 25, 2008Oct 9, 2012Electro Scientific Industries, Inc.Method and apparatus for detecting defects using structured lightUS8305568Feb 22, 2011Nov 6, 2012Hitachi High-Technologies CorporationSurface inspection method and surface inspection apparatusUS8446578Nov 16, 2009May 21, 2013Nikon CorporationDefect inspection apparatus, defect inspection method and method of inspecting hole patternUS8462330Jan 31, 2012Jun 11, 2013Hitachi High-Technologies CorporationMethod and apparatus for detecting defectsUS20090245614 *Mar 25, 2008Oct 1, 2009Electro Scientific Industries, Inc.Method and apparatus for detecting defects using structured light* Cited by examinerClassifications U.S. Classification356/237.2International ClassificationG01N21/88, G01N21/956, G01N21/95, G06T7/00Cooperative ClassificationG01N21/9501, G01N21/00, G06T7/0004, G06T2207/30148European ClassificationG06T7/00B1, G01N21/95ALegal EventsDateCodeEventDescriptionJan 8, 2014FPAYFee paymentYear of fee payment: 4May 3, 2011CCCertificate of correctionDec 4, 2008ASAssignmentOwner name: HITACHI HIGH-TECHNOLOGIES CORPORATION, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HITACHI, LTD.;HITACHI HIGH-TECHNOLOGIES CORPORATION;REEL/FRAME:021952/0638Effective date: 20081114RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google