JP2004524538A - Improvement of defect detection system - Google Patents

Abstract

Scattered light from the sample surface (20a) is focused by a concentrator (38, 52) that focuses light substantially symmetric about a line perpendicular to the surface (20a). The focused light is directed to the path at different azimuths and information about the relative azimuthal position with respect to the focused scattered light line is stored. The focused light is converted to respective signals representing light rays scattered at different azimuthal angles with respect to a perpendicular line. The presence / absence and / or characteristics of the abnormality are determined from this signal. Alternatively, the light beams focused by the concentrators (38, 52) are filtered by a spatial filter having an annular gap at an angle corresponding to the expected pattern scattering angle difference. The signals obtained from the narrow and wide angle focusing paths are compared to discriminate between microscratch and particles. Forward scattered light is focused from other rays and compared to discriminate between microscratch and particles. The intensity of the scatter is measured when the surface is sequentially illuminated with S and P polarized light and compared to distinguish between microscratch and particles.
[Selection diagram] Fig. 1

Description

【Technical field】
[0001]
The present invention relates generally to defect detection, and more particularly to detecting surface abnormalities such as particles, as well as defects caused by surfaces such as crystal-induced particles (COP), surface roughness, microscratch, etc. Regarding system improvement.
[Background Art]
[0002]
SP1 available from KLA-Tenker Corporation of San Jose, California, the assignee of the present application.^TBI The (trademark) detection system is particularly effective for detecting a defect on a semiconductor wafer on which no pattern is formed. SP1^TBI The system provides superior sensitivity to defects when inspecting bare or unpatterned wafers, rather than using it to inspect patterned wafers, such as wafers with memory arrays. Present. In this system, all light is collected by a lens or elliptical mirror and directed to a detector, producing a single output. Thus, when the pattern on the wafer collects these signals and sends them to the detector to generate Fourier and / or other strong scattered signals, the output of the signal detector becomes saturated and the It becomes impossible to provide effective information for detecting the failure of the device.
[0003]
Conventional techniques for detecting defects on a wafer are configured to be compatible with either inspection of patterned wafers, or of inspection of unpatterned or bare wafers. Not suitable for doing both. Although a detection system for patterned wafers can be used to inspect unpatterned wafers, this system is generally less than optimal for that purpose. Systems designed for inspection of unpatterned or bare wafers, on the other hand, handle diffraction and other scattering caused by pattern structures on patterned wafers for reasons such as those described above. Is difficult.
[0004]
Inspection of patterned wafers has used a completely different inspection system. A commercially available system, known as the AIT ™ inspection system, is available from KLA-Tenker Corporation of San Jose, California, the assignee of the present application. This system has been described in various patents, such as US Pat. No. 5,864,394. The AIT system employs a spatial filter to shield the detector from diffraction and scattering due to the pattern structure on the wafer. The design of this spatial filter may be based on conventional knowledge of the pattern structure, but can be very complex. In addition, the system employs a die comparison process to more accurately identify the presence or absence of a defect.
[Patent Document 1]
U.S. Pat. No. 5,864,394
[Patent Document 2]
US Patent Application No. 08 / 770,491
[Patent Document 3]
US Patent No. 6,201,601
DISCLOSURE OF THE INVENTION
[Problems to be solved by the invention]
[0005]
None of the above equipment has been completely satisfactory in inspecting patterned wafers. Therefore, there is a need for an improved defect detection system that can reduce the above-described problem with respect to a wafer on which a pattern is formed. Furthermore, in order to save the space required for in-line inspection, it is desired to provide equipment that is optimal for inspecting both a patterned wafer and a non-patterned wafer.
[0006]
Chemical mechanical planarization (CMP) technology is widely accepted in the semiconductor industry. However, even in the CMP process, if the defect cannot be properly controlled, various defects that can have a large impact on the production amount of the integrated circuit (IC) are generated. In the case of poor CMP, micro-scratch has a great influence on IC production. Therefore, it is desirable to be able to detect micro-scratch and other CMP defects and differentiate them from particles.
[0007]
An important parameter for monitoring the quality of an unpatterned or bare film on a silicon wafer is the surface roughness. The surface roughness is generally determined by the KRP-Tenker Corporation's HRP® instrument, the assignee of the present application, or other instruments, such as an atomic force microscope, or other types, such as a scanning tunneling microscope. Measured by a scanning probe microscope. One of the drawbacks of such devices is that their operation speed is slow. Therefore, it is desirable to provide an alternative system that can measure surface roughness at a much faster rate than the devices described above.
[Means for Solving the Problems]
[0008]
One aspect of the present invention is the SP1^TBI It is based on the viewpoint that the concentrator in the instrument stores information on the azimuth of the scattered light from the surface to be inspected. Therefore, SP1^TBI If the scattered light focused by the concentrator of the type used in the equipment is separated into different azimuth angles and the focusing path is separated, the above-mentioned problem can be solved and the equipment can detect the patterned wafer. Can also be configured as optimal. This makes it possible to obtain a small device capable of measuring a defect of a wafer on which a pattern is formed. SP1^TBI In addition to the elliptical mirrors used in the instrument, other azimuthally symmetric concentrators may be used, such as parabolic mirrors used with one or more lenses.
[0009]
SP1^TBI Like a system, a surface inspection system according to one aspect of the present invention focuses light scattered from a surface by a concentrator for focusing the scattered light substantially symmetrically about a line perpendicular to the surface. By focusing the scattered light at a different azimuth or another direction with respect to the perpendicular line and directing the scattered light to a different path, these paths allow the scattered light at a position corresponding to the relative azimuth of the scattered light to be related. Can carry information. Preferably, these paths are separated by a separator to reduce crosstalk. The focused scattered light carried through at least a portion of the path can be used to determine the presence or characteristic of an anomaly within or on the surface. Further, the ability to consider the same event from multiple directions can greatly simplify the process of real-time failure classification (RTDC).
[0010]
In the scheme described above, by directing only a portion of the focused light beam to different paths and the remaining portion of the focused light at different azimuths to a single detector, the conventional SP1^TBI If a single output is generated as in the mechanism described in the above, the system can be used to inspect both a wafer on which a pattern is not formed and a wafer on which a pattern is formed. That is, while preserving the azimuth information, a part of the light beam converged by the above-described method is redirected to a different path, thereby achieving^TBI By changing the mechanism described above, a multipurpose tool that can optimally execute inspection of both a wafer on which a pattern is not formed and a wafer on which a pattern is formed is realized. In this way, the semiconductor manufacturer does not need to separately prepare optimal tools for detecting a wafer on which a pattern is formed and a wafer on which a pattern is not formed.
[0011]
In the mechanism described above, rays focused at different azimuths relative to a line perpendicular to the surface are directed to different focusing paths and converted to different signals, thus discarding signals containing pattern diffraction. The remaining signals, which do not include pattern scattering, can be used to detect and classify anomalies inside or on the surface of the wafer. The system described above is particularly useful for inspection of semiconductor wafers, but also for inspection of anomalies in other surfaces and other applications, such as flat panel display systems, magnetic heads, magnetic and optical recording media, etc. can do.
[0012]
Another aspect of the present invention is to focus by a concentrator (as described above) using a spatial filter with an angled gap corresponding to the angular difference of the ray components expected to be scattered by the pattern on the surface. This is based on the viewpoint that the filtered light can be filtered. Thus, the filtered light at some locations relative to the filter on the surface contains information about surface defects that were exposed due to scattering of the pattern that could interfere with the measurement. By detecting such light rays with a detector, the presence or absence and / or characteristics of an abnormality inside or on the surface can be detected using the output of the detector.
[0013]
SP1^TBI Tools or the systems described above can be used to distinguish between CMP particles and microscratch. Scattered light along a direction close to the vertical direction is focused by a first detector, and scattered light along a direction away from the vertical direction is focused by a second detector. By determining the ratio from the outputs of the two detectors, it is determined whether the surface abnormality is a micro scratch or a particle.
[0014]
CMP micro-scratches tend to scatter light from obliquely incident light forward. On the other hand, particles scatter such light rays more evenly. Light rays scattered in the forward scattering direction by the surface are focused separately from light scattered in other scattering directions. Two different signals are derived from the separately focused scattered light and compared to determine whether the anomaly on the surface is a microscratch or a particle.
[0015]
In another aspect of the present invention, S-polarized light and P-polarized light sequentially enter the surface obliquely during two different types of surface scanning. Light rays scattered by the faults during the first and second scans are focused and output a pair of signals representing scattered light of two different incident polarizations. The pair of signals is compared to a reference to determine if the surface anomaly is a microscratch or a particle.
[0016]
In order to more quickly perform the process of determining the surface roughness of the thin film, a database that associates the haze value with the surface roughness of the thin film is created. Surface haze value is SP1^TBI The surface roughness value measured with a tool such as, or one of the systems described above, can be determined from the measured haze value and a database. For example, the database contains SP1 for measuring the haze value of a representative thin film.^TBI And a HRP® profiler or other type of profilometer or a scanning probe microscope for measuring the surface roughness of such membranes with a tool like the one above or one of the systems described above. .
[0017]
Aspects of the invention as described above can be used individually or in combination to achieve the advantages described herein.
[0018]
Further, in order to make the description easy to understand, in the present application, the same components are denoted by the same reference numerals.
BEST MODE FOR CARRYING OUT THE INVENTION
[0019]
FIG. 1 shows SP1 available from KLA-Tenker Corporation of San Jose, California, the assignee of the present application.^TBI 1 is a schematic diagram of a trademark system 10. SP1^TBI Aspects of system 10 are described in U.S. patent application Ser. No. 08 / 770,491, filed Dec. 20, 1996 and U.S. Pat. No. 6,201,601. These patent applications and patents are expressly incorporated herein by this reference. To simplify the drawing, some of the optical elements of the system, such as components that direct the illumination light to the wafer, have been omitted. The wafer 20 to be inspected is illuminated by normal incident light 22 and / or oblique incident light 24. The wafer 20 is supported on a chuck 26 rotated by a motor 28 and diverted by a gear 30, and light 22 and / or 24 travels a spiral path on the surface of the wafer 20 to inspect the surface of the wafer. Irradiate the area or spot 20a to be tracked. Motor 28 and gear 30 are controlled by controller 32, as is well known to those skilled in the art. Alternatively, light 22, 24 travels in a manner well known to those skilled in the art and tracks a spiral path or another type of scanning path.
[0020]
Areas or spots 20a illuminated by one or both lights on wafer 20 scatter light from these lights. Light rays scattered by region 20a, which is perpendicular to the surface of the wafer and along line 36 passing through region 20a, are focused by lens concentrator 38, collected and directed to PMT 40. The lens 38 focuses the scattered light along a direction close to the vertical direction, such a focusing path is referred to herein as a narrow-angle path, and the PMT 40 is referred to as a dark-field narrow-angle PMT. If desired, one or more polarizers 42 may be placed in the path of the focused light in the narrow angle path.
[0021]
Light rays scattered along the direction away from the vertical direction 36 at the spot 20 a of the wafer 20 illuminated by one or both of the lights 22, 24 are focused by an elliptical concentrator 52 and pass through an aperture 54 and an optional polarizer 56. The light is condensed on the dark field narrow angle PMT 60 through the PMT 60. Compared to lens 38, elliptical concentrator 52 is able to focus scattered light along a direction at a greater angle with respect to vertical direction 36, and such a focusing path is referred to as a wide-angle path. The outputs of the detectors 40, 60 are sent to a computer 62, which processes the signals to determine the presence or absence of an abnormality and its characteristics.
[0022]
SP1^TBI The system is advantageous for inspection of unpatterned wafers because the focusing optics (lens 38 and mirror 52) are rotationally symmetric with respect to the vertical direction 36, and the direction of the defect on the surface of the wafer 20 The orientation of the system shown in FIG. Further, the angle range of the scattering space targeted by these concentrators matches the angle range required for detecting the abnormality in the inspection of a wafer on which no pattern is formed.
[0023]
However, in addition to the above features, SP1^TBI An important feature of the system 10 is that its lens concentrator 38 and elliptical mirror concentrator 52 both store azimuthal information contained in light scattered by imperfections on the surface of the wafer 20. . Thus, certain defects and / or patterns on the wafer may cause light rays to be scattered in a certain azimuthal direction. By utilizing the azimuth information stored in the beams focused by the concentrators 38 and 52, the system 10 can be advantageously adapted and modified for the detection of defects on patterned wafers.
[0024]
One aspect of the present invention is to separate the light rays focused by lens 38 and / or elliptical mirror 52 so that light rays scattered in different azimuthal directions can be separately detected. In this method, there is a possibility that the detector that detects the light beam diffracted or scattered by the pattern is saturated. However, other detectors that do not detect these diffraction or scattered light are used for detecting and classifying the defect on the wafer 20. An effective signal can be generated. Since the lens 38 and the elliptical mirror 52 store the information of the azimuth angle of the scattered light, the knowledge about the pattern and the type of the defect existing on the wafer 20 is used for designing and arranging a plurality of detectors. Can be advantageously detected and classified. This is especially true for regular patterns, such as the storage structures formed on wafer 20 described below. This is because the rays diffracted by such a regular pattern are regular.
[0025]
FIG. 2 is a schematic diagram showing a focused hollow conical light beam that can be focused by lens 38 or mirror 52. The lens 38 of FIG. 1 employs a spatial filter (not shown in FIG. 1) to prevent the specular reflection of the vertically incident light 22 from reaching the detector 40. As a result, the light beam focused on the PMT 40 has a converging hollow conical shape as shown in FIG. In the case of the elliptical mirror 52, since the mirror is not perfectly elliptical, it focuses only light rays scattered at a large angle with respect to the vertical direction 36 without focusing light rays scattered near the vertical direction. The light beam focused on the detector 60 also has a converging hollow conical shape as shown in FIG.
[0026]
FIG. 3A is a schematic diagram illustrating a possible arrangement of a multi-fiber path that receives the focused conical light beam shown in FIG. 2, as focused on a mirror 52, for example, and illustrates a preferred embodiment of the present invention. The configuration of FIG. 3A includes two substantially concentric annularly arranged optical fiber paths 72 used to carry the focused scattered light in the focused hollow cone shown in FIG. Fourier components or other patterns scattered from the pattern on the wafer 20 reach a portion of the fiber 72, thereby saturating the detector that detects light rays from that path. However, there are other fiber optic paths that do not accept such undesirable pattern scattering. By using the multi-fiber path 72, the focused scattered light is effectively split into different sectors or segments so that only a portion of the fiber path receives a strong signal and is saturated by Fourier or other pattern scattering. Also, information that can be analyzed to detect an abnormality from the remaining routes can be conveyed. As described below, since the information of the azimuth of the focused scattered light in the conical shape of FIG. 2 is stored, various schemes are adopted, and when the division method of FIG. The effects of scattering can be minimized.
[0027]
Different types of detectors may be used to detect light beams carried by the fiber path 72, such as the multi-anode PMT shown in FIG. 3B. However, when using a multi-anode PMT, there is a nominal 3% crosstalk between two adjacent paths. To avoid such crosstalk, the fibers 72 are aligned with every other PMT anode, as shown in FIG. 3B. FIG. 3B is a schematic diagram of a multi-anode PMT. As shown in FIG. 3B, only the shaded anode 74 is aligned with the fiber 72, and the anode 76 is not aligned with any of the fibers 72. This avoids the 3% crosstalk that occurs when all of the anodes shown in FIG.
[0028]
FIG. 4 shows an arrangement 80 of fiber paths or multiple detectors 82 for narrow angle paths. As shown, the fiber or detector 82, along with the focused scattered light shown in FIG. 2 on the narrow angle path focused by the lens 38, splits the light beam in the same manner as on the wide angle path.
[0029]
FIG. 5A is a partial sectional view and a partial schematic view of the failure detection system, showing an embodiment of the present invention. To simplify FIG. 5A, the two illumination beams 22 and 24, the computer 62, and the mechanism for moving the wafer are not shown. Light rays scattered by the spot 20 a on the wafer 20 and focused by the lens 38 are reflected by the mirror 102 to the detector 40. Since the stopper 104 prevents the specular reflection of the normal incident light 22 from the detector 40, a conical focused light as shown in FIG. 2 is generated. The light converged and condensed by the lens 38 and reflected by the mirror 102 passes through the beam splitter 106, and the portion of the condensed light that has passed through the beam splitter is condensed on the detector 40, and the normal SP1^TBI Produces a single output like an operation. The beam splitter 106 reflects a portion of the focused light from the lens 38 and redirects to the optical fiber array 80 of FIG. Preferably, the dimensions of the optical fiber 82 and of the hollow cone reflected by the beam splitter 106 are such that the fiber 82 focuses and transports most of the hollow cone light rays. Each fiber 82 is then connected to a corresponding detector or detection unit of a multi-unit or multi-element detector. Similarly, beam splitter 112 redirects a small portion of the light rays focused by elliptical mirror 52 toward an array 70 'of fiber optic paths 72, shown in greater detail in FIG. 5B, where each path 72 is separate. Or a separate detection unit of a multi-element detection system (not shown). As shown in FIG. 5A, beam splitter 112 is configured to divert light rays toward array 70 ′ only within small diameter ring 114. Most of the light beam converged by the mirror 52 passes through the beam splitter 112, and is condensed on the detector 60 to generate the normal SP1 light.^TBI Produces a single output, as in an operation. In FIG. 5A, the irradiation beams 22, 24 and the mechanism for moving the wafer are omitted for the purpose of simplifying the drawing.
[0030]
As is clear when comparing the system 10 of FIG. 1 with the system 100 of FIG. 5A, the system 100 has substantially all the characteristics of the system 10 of FIG. Further, the system 100 redirects a portion of the scattered light focused by the lens 38 and the mirror 52, respectively, directs it toward the fibers 82, 72, and conveys the split light to a separate detector or unit. I do. This system is small and has the SP1 shown in FIG.^TBI The space required separately as compared with the system 10 can be minimized. In this way, the integrated bonding equipment can be optimized and used for both unpatterned and patterned wafers, and two separate inspections for two types of wafers. Eliminates the need for equipment.
[0031]
When inspecting only the patterned wafer, another defect inspection system 150 shown in FIG. 6A can be used. In FIG. 6A, to simplify the drawing, the irradiation beams 22, 24, the computer 62, and the mechanism for moving the wafer are omitted. As shown in FIG. 6A, the scattered light focused by lens 38 and mirror 52 is reflected by mirror 112 'and directed toward a system of optical fibers 152, shown in more detail in cross-section in FIG. 6B. As shown in FIG. 6B, system 152 includes an annularly arranged fiber 82 for carrying the scattered light focused by lens 38 and an annularly arranged fiber for carrying the scattered light focused by mirror 52. 72. As described above, each of the fibers 72 and 83 is connected to a separate detector or detection unit of a multi-unit detector.
[0032]
Although the detectors are arranged in a single ring in FIGS. 4 and 5B, a plurality of detectors can be employed as shown in FIG. 3A. The optical transmission cores of the optical fibers located adjacent to each other in each of the two arrangements 70, 70 ', 80 are separated from each other by cladding surrounding the cores, reducing crosstalk between adjacent cores. is there. Clearly, optical paths other than fibers can be used and are within the scope of the present invention. When such a path does not include a separator such as a clad in the case of an optical fiber, crosstalk can be reduced by using another optical separator.
[0033]
Referring to FIG. The diversion of some of the focused scattered light from detectors 40 and 60 may reduce the particle sensitivity of system 100 somewhat when inspecting unpatterned wafers, but this reduction in sensitivity is not The inefficiency of the narrow and wide angle focusing paths of system 100 is insignificant. If desired, when inspecting an unpatterned wafer, the light beams carried by fibers 72 and 82 may be directed to detectors 40 and 60, respectively, to substantially restore the sensitivity of system 100 and reduce its sensitivity. The sensitivity of the system 10 of FIG. 1 may be substantially the same.
[0034]
The systems 100 and 150 of FIGS. 5A and 6A are particularly advantageous in distinguishing microscratches and particles. The scattering pattern due to the micro-scratch has the highest concentration of energy, has the highest uniformity of detection when illuminated vertically and captured in a nearly vertical or narrow angle path focused by lens 38. The only indication of a scratch in the form of a longitudinal pattern in the far field allows a simple classification method. Thus, a hollow cone of light collected by the lens 38 toward the fiber 82 when the output of these fibers is redirected by the beam splitter 106, which is directed to a multi-channel detector or an array of individual detectors. By arranging eight or more fibers 82 arranged in a ring in the optical path, a simple process of comparing a signal obtained through two fibers diametrically opposed to each other with a signal from the other fiber is used. Thus, the presence or absence of micro scratch can be determined. When skewed, the microscratch produces a scattering pattern different from that of particles by using the multiple detection channels described above for pattern inspection, ie, the multi-fiber units 70, 70 '. In both wide-angle and narrow-angle paths, it is also possible to place individual detectors or multi-element detection systems directly in the focused hollow conical optical path instead of individual optical fibers.
[0035]
<Array wafer>
When inspecting a wafer having memory cells on its surface using the systems 100 and 150, the Fourier component from the memory array spins as the wafer rotates. Thus, these elements rotate and assume different azimuthal angles with respect to the vertical direction 36 of FIGS. 1, 5A, 6A. That is, these Fourier components are carried by different fibers 71 and 82 as the wafer rotates. Since the array of memory cells has different dimensions in the X and Y directions of the wafer, as the wafer rotates, the number of detectors saturated by Fourier components changes. Thus, the dimensions of the memory cell in the X and Y directions can be known, and the number of Fourier diffraction elements can be predicted. Alternatively, a learning cycle is performed during the first initialization step to determine the maximum number of Fourier components that must be removed by recognizing the maximum number of detectors at very strong or saturated output. In a subsequent measurement step, only that number of detector outputs are removed, but the output removed is the saturated output or the output with the maximum value. For example, in the case of a multi-anode PMT, when each anode is used connected to a corresponding fiber, crosstalk can be reduced by removing elements adjacent to the detector with the highest output. For example, if the Fourier component is 3 at one location of the wafer and three direct components are removed at the other two locations along with two adjacent components, a total of nine detector outputs are removed. become. This leaves seven available detector outputs. This number is maintained regardless of whether the wafer is facing the right way. This allows the user to retain sizing options for the particles.
[0036]
Preferably, fibers 72, 82 are rotationally symmetric about a direction such as axes 74, 84 shown in FIGS. 3A, 4, 5B and 6B. With this arrangement, the light scattering directions are located in the same angular segment, and the light scattered in each segment is focused by the corresponding fiber. As the beam splitters and mirrors 102, 112, 112 'reflect or redirect the portion of the light beam focused by lens 38 or mirror 52, the azimuthal position of the focused scattered light is such that the reflected or redirected light beam is It is stored when it is led to 82. When the light ray is reflected or redirected in this manner, the azimuths of the focused scattered light about axes 74, 84 corresponding to the vertical direction 36 and the axes 74, 84 corresponding to the azimuthal position relative to the vertical direction 36. The position is saved.
[0037]
As described above, the azimuthal characteristics of the scattered light are preserved for both narrow and wide angle paths. The scattering pattern due to the microscratch illuminated by the light 22 in a substantially perpendicular illumination direction has the highest energy concentration and the highest detection uniformity when captured in a narrow angle path. Furthermore, the only indication of scratches in the form of a longitudinal pattern in the far field allows a simple classification method. For example, referring to FIG. 4, eight fibers 82 are used in an array 80 to receive and carry the scattered light in the hollow cone of light of FIG. When connected to individual detectors, the sum of the two signals from the two diametrically opposed fibers is compared to the output signals of the remaining detectors to determine the presence or absence of microscratch. Confirm.
[0038]
As described above, once all of the scattered light from the illuminated spot 20a is focused and directed to a single detector, the presence of Fourier or other scattering components saturates the detector and causes the system to saturate. No useful information can be provided about the anomalies in the illuminated spot. For this reason, applicant proposes to split the focused scattered light into different segments. If the focused scattered light is split into only a few segments, such as two or three, only two or three output signals are generated, and the two or three segments still contain pattern scattering, It is likely that two or three detectors will saturate again and will not be able to obtain useful information about the anomaly. Therefore, in order to make the detection signal effective, it is preferable to divide the detection signal into small portions sufficiently small so that there is no noticeable pattern scattering. Therefore, if the lines connecting the various Fourier or other scattering components and the vertical direction 36 do not approach each other more than δφ in the angular direction, each detector can receive the scattered light focused within the stop angle not exceeding δφ. It is preferable to divide into Thus, there are at least some detectors that do not receive Fourier or other pattern scattering, and will produce valid output signals that can reliably confirm the presence or absence or characteristics of the sample surface. Therefore, when the split light beam is conveyed to a plurality of optical fibers, it is preferable that at least some of the fibers receive a light beam focused within an azimuth angle of δφ or less.
[0039]
Another arrangement for splitting the scattered light focus is shown in FIG. FIG. 7 is a top view of a rotationally symmetric concentrator, such as an elliptical or parabolic mirror 200 having two stops 202,204. Preferably, the two stops are centered at + 90 ° and -90 ° azimuthal positions for the oblique light 24 shown in FIGS. Multi-element detectors or detector arrays 206, 208 are located in each of the two stops. In this case, the detector or array may be a multi-anode PMT or a multi-PIN diode array. FIG. 8A is a schematic side view of a part of the detector or detector arrays 206 and 208 in FIG. As shown in FIG. 8A, each of the detection units 206a and 208a has a substantially rectangular shape having a width w. Preferably, the detection units 206a and 208a have their long sides parallel to the substantially vertical direction 36. Thus, each of the detection units 206a, 208a has a center within a small angle sector whose range is defined by the width of the long element 206a, 208a is less than or equal to δφ. To focus the scattered light toward axis 36, at least a portion of the detector outputs a useful signal to detect and characterize anomalies on the sample surface without being blocked by pattern scattering.
[0040]
By arranging the two detectors or detector arrays 206 and 208 at the apertures 202 and 204, respectively, the detection units 206a and 208a output effective signal components for detecting abnormality. The process of either predicting or making decisions through the immediate learning cycle as described above is applied to the two detectors or detector arrays 206, 208 to determine the maximum number of pattern scatter components that need to be removed. And an abnormality can be detected using the remaining detection signals.
[0041]
Semiconductor circuit dimensions are becoming increasingly smaller. Thus, the cell dimensions have been similarly reduced and the number of Fourier or other scattering components has been correspondingly reduced. If the cell size is large, the width w of the detectors or the detector units of the detector arrays 206 and 208 must be reduced so that the two detectors or each detector unit of the detector arrays 206 and 208 are saturated and the valid signal Can not be obtained. This can be corrected by the mechanism shown in FIG. 8B.
[0042]
As shown in FIG. 8B, the signal collection capabilities of the detectors or detector arrays 206, 208 can be further enhanced. If the number of pattern scatters increases beyond the design value of the detector or detector array, then using the arrangement of FIG. 8B allows anomaly detection despite the increase. As shown in FIG. 8B, the multiple detection units of the detectors or detector arrays 206, 208 are labeled D1, D2,..., D2n, D2n + 1, respectively, from the same side to the opposite side. The odd detection units D1, D3, D5..., D2n + 1... Of the multi-unit detector or detector array 206 are covered by a spatial filter 216. The even detection units D2, D4, D6 ... D2n ... of the detector or array 208 are covered by a spatial filter 218 shown in Fig. 8B. Thus, if there is a relative rotational movement between the sample surface and the detector or arrays 206, 208, the uncovered detection unit will output a valid signal.
[0043]
FIG. 9A is a cross-sectional view of the concentrator 52 of FIG. 1, modified to include a diaphragm or detector or detector array of the type shown in FIGS. 7, 8A and 8B. The two stops 202, 204 are preferably dimensioned such that each side is centered at an azimuthal position of ± 90 ° and has an azimuthal gap of about 10 ° to 40 °. The aperture is located only toward the bottom of the concentrator, and only scattered light along a direction near the surface can be detected by the detectors or detector arrays 206,208. The scattered light from the illuminated spot 20a is focused using two lenses 222 and 224 having an appropriate F-number, and collected on the respective detectors or detector arrays 206 and 208. Two detectors or detector arrays can be mounted in the back focal plane of the two lenses 222,224.
[0044]
Masks 216, 218 are placed between the spots 20a illuminated by the filter wheels 226, 228 rotated by the actuators 232, 234 and the detectors or detector arrays 206, 208. This method is well known to those skilled in the art, so the connection between these two actuators and the wheel is not shown and a detailed description of its operation is not necessary here. For simplicity, only the mask portions 216, 218 of the two filter wheels 226, 228 are shown in FIG. 9A. The characteristics shown in FIGS. 9A, 9B, and 9C can be combined with the systems 100, 150 of FIGS. 5A, 6A to further enhance their versatility. When the combined device is used for inspection of a wafer on which a pattern is not formed or a bare wafer, for example, a decrease in sensitivity due to the two apertures 202 and 204 is insignificant. Further, when inspecting an unpatterned wafer, the output of the detector or detector arrays 206, 208 can be added to the output of the detector 60, at least partially restoring the sensitivity of the system. The characteristics shown in FIGS. 9A-9C can also be advantageously used to suppress extraneous signals due to film roughness. In such a situation, the S-polarized oblique irradiation light 24 is output, and only the S-polarized light scattering from the irradiated spot 20a is focused, because the film roughness scatters P-polarized light more efficiently than S-polarized light. Is preferred. This can be conveniently achieved by the filter wheels 226,228. The filter wheels 226, 228 are rotated using the actuators 232, 234, with the S-polarizer 236 replacing the mask 216 of FIG. 9A and another S-polarizer also replacing the mask 218 of FIG. 9A. As can be seen from FIG. 9A, this arrangement is advantageous because the two filters 236, 238 are located near the surface of the wafer 20 and thus the focused light is confined to a scattering angle very close to the wafer surface. If the surface of the film is very rough, the upper half of the S-polarizer can be shielded using semi-circular opaque screens 236 ', 238' in the filter wheel to further limit the elevation angle of focus. For example, a semi-circular S-polarizer can limit the aperture elevation angle of the stop to about 55 to 70 degrees from the vertical 36. This is useful because the amount of scattering due to film roughness increases with the elevation angle to the wafer surface. FIG. 9C illustrates another filter wheel that can be used to inspect bare wafers or unpatterned wafers.
[0045]
If the expected direction of the pattern scattering surface is known, the spatial filter can be designed to block such scattering, thereby detecting only scattering due to anomalies on the surface. FIG. 10 is a schematic diagram illustrating a two-dimensional Fourier component of an array structure when illuminated by vertically incident light. As the sample rotates, all spots located at the intersection of the XY lines rotate, creating a circle. These circles represent the position of the Fourier component when the wafer rotates. The dark opaque circle in the center indicates the 0 to 5 degree blocking state of the focusing space by the stopper 104 of FIG. 5A. FIG. 10 shows that there is a gap between the circles where no Fourier component exists. At least in theory, it is possible to construct a programmable filter (eg, a liquid crystal filter) that blocks an annular band having any radius. By constructing a simple spatial filter, many of the objects of the present invention can be achieved. Thus, the cell size of a typical memory array on a wafer, if its XY dimensions are less than about 3.5 microns, for example, at 488 nanometer wavelength light used for illumination light 22, 24, would One Fourier component is about 8 ° with respect to the vertical direction 36. Thus, if a spatial filter is employed, blocking any focused light in a narrow angle path that is greater than or equal to 8 ° with respect to the vertical direction 36 will result in about 8 ° from the central obstacle rim (ie, 5 or 6 °) A 2 or 3 ° annular gap remains up to the rim of the variable aperture. Under these circumstances, when the wafer spins, the Fourier components cannot pass through the annular gap and scattering from the array is suppressed. In some embodiments, the spatial filter used leaves an annular gap between about 5 and 9 degrees from the vertical 36.
[0046]
In the example described above, the spatial filter is designed for a narrow angle path. It will be appreciated that similar spatial filters can be designed for wide-angle paths. Such and other modifications are within the scope of the present invention.
[0047]
As previously described, the focusing iris of at least some of the detectors is expected to have a pattern scatter that is expected to ensure that at least some of the detectors receive a valid signal that is not blocked by Fourier or other pattern scatter. Is preferably equal to or less than the angle difference between the two. For this purpose, a spatial filter is configured to block all rays focused in a narrow or wide angle path, except for small stop angles where the stop angle is less than or equal to the angle difference between pattern scattering. can do. Placing such a spatial filter between the illuminated spot 20a and a detector, such as detector 40 or 60, causes the Fourier component to spin through this small aperture. If no component passes, the data is valid for detecting anomalies. If not, the signal is very strong or saturated. Thus, at the end of the helical scan, the wafer map will be a series of saturated and data valid sectors. If the scan is repeated one more time, during the first scan the center position of the aperture angle deviates from that position by the minimum angular difference of the patterned scattering, and as before, the data is valid and saturated sectors Is obtained. However, in the region that was saturated during the first scan, valid data can now be obtained. Thus, by combining the two data sets using a logical OR operation, a complete wafer map with valid data can be obtained.
[0048]
The steps described above can be simplified by using an asymmetric mask 250 as shown in FIG. As shown in FIG. 11, the two fan-shaped apertures 252 and 254 are shifted from the positions diametrically opposed by an angle equal to the predicted minimum angle difference of pattern scattering. When such a filter is placed between the illuminated spot 20a and the detector 40 or 60 shown in FIG. 1, the detectors 40 and 60 produce a complete wafer map as the wafer is scanned.
[0049]
FIG. 12 is a schematic diagram of a failure detection system illustrating another embodiment of the present invention. As shown in FIG. 12, when illuminated by light (not shown), such as lights 22 and 24 of FIG. 1, it is focused by a concentrator 52 (not shown in FIG. 12 for simplicity of the drawing). The scattered light is collected on a triangular device 262 having two mirrors 262a, 262b on opposite sides of the device. The irradiation beam is also omitted for simplification. Thus, the scattered light is reflected by device 262 into two opposing hemispheres. Mirror 262a reflects half of the scattered light to PMT1, mirror 262b reflects the other half of the scattered light to PMT2, and provides an asymmetric mask 250 between mirror 262a and PMT1 and between mirror 262b and PMT2. be able to. In this way, two wafer maps effective for abnormality detection and classification can be obtained by using two PMTs.
[0050]
<Detection of CMP failure>
One aspect of the present invention includes two algorithms for classifying a CMP failure. The first method is based on the spatial distribution of light scattered by the defect. Theoretical simulations and experimental results show that light scattered by the CMP microscratch first travels in the direction of specular reflection, and that light scattered by particles (especially small particles) has a different spatial distribution. . As a result, failure classification can be achieved by measuring the distribution of scattered light. This can be done by placing multiple detectors at appropriate locations around the scatterer. Alternatively, a single detector is used with multiple spatial filters / masks. Three different ways of implementing this algorithm will be described.
[0051]
The second algorithm is based on the double polarization method. This method uses the incident S and P polarizations to compare scattered signals from defects. Theoretical simulations have shown that the intensity of the scattering is proportional to the intensity of the local interference seen by the defect. The intensity of this interference is different for S and P polarizations and depends on the height above the surface of the wafer. Thus, there is a large difference between the intensity of the interference seen by the particles (defective on the surface) and the intensity seen by the microscratch (at or below the wafer surface). Failure classification can be achieved by comparing the intensity of the scattered signal using S and P polarized incident light or light.
[0052]
<Operation details>
In the following paragraph, Surfscan SP1^TBI The execution / operation of the present invention in the system will be described. However, the algorithm is SP1^TBI It is not limited to a system, but can be implemented with any light scattering tool. All the algorithms described below require a PSL calibration curve for all paths used. These are extremely important factors for the successful classification of CMP failure.
[0053]
Algorithm # 1, execution # 1, dual channel, oblique incidence, single scan
The SP1 system has four darkfield paths, DWN, DNN, DWO, and DNO. DWN represents the path that carries the scattered light focused by the elliptical mirror from the vertically illuminated light. DNN represents a path for conveying scattered light focused by a lens concentrator from perpendicular illumination light. DWO represents a path for conveying scattered light focused by an elliptical mirror from oblique illumination light. DNO represents a path for conveying scattered light converged by the lens concentrator from oblique irradiation light. The dual channel method uses two dark field paths, for example, DWO and DNO paths. The principle of this method is based on the fact that the spatial scattering patterns of particles and microscratches are different. The particles scatter the light in all directions, which can be focused by both darkfield paths. However, microscratch preferentially scatters light in one direction, so that the signal captured on one path is much larger than that captured on another path. For example, using the sloped paths DWO and DNO, micro-scratch is preferentially caught in the DWO path, or the signal in the DWO path is much larger than the signal in the DNO path. To distinguish microscratches from particles, the dimensional ratio of each defect caught in the DWO and DNO paths is calculated. If the size ratio of the defect is close to 1, the defect is classified as a particle. However, if the dimensional ratio of defects is less than a certain number (for example, 0.8), it is classified as a micro scratch. If a defect is caught only on the DWO route and not on the DNO route, it is classified as a CMP microscratch. If a defect is caught only on the DNO route and not on the DWO route, it is classified as a particle.
[0054]
Algorithm # 1, execution # 2, dual channel, normal incidence, single scan
Execution on a vertical path is similar to execution on an oblique path. The difference is that the light scattered from the CMP microscratch preferentially travels to the normal incidence narrow angle path (DNN) instead of the wide angle (DWN) path. This is due to the fact that the CMP micro-scratch scattered light travels in the direction of specular reflection. The defect classification is performed by calculating the dimensional ratio of the defects caught in both the DNN and DWN paths. If the size ratio of the defect is close to 1, the defect is classified as a particle. However, if the size ratio of the defect is larger than a certain number (for example, 1.6), it is classified as a micro scratch. If a defect is caught only on the DNN route and not on the DWN route, it is classified as a CMP microscratch. If the defect is caught only on the DWN route and not on the DNN route, it is classified as a particle.
[0055]
Algorithm # 1, execution # 3, single channel, oblique incidence, 2-mask, double scan
A third method for performing algorithm # 1 uses two masks. One mask (# 1) is designed to preferentially catch scattered light from the CMP microscratch. This mask is shown in FIG. 13A, where shaded areas indicate areas where light rays are blocked, and non-shaded areas are areas where light rays can pass. The other (# 2) is designed to block light scattered by the CMP microscratch. This mask is shown in FIG. 13B, where shaded areas indicate areas where light rays are blocked, and non-shaded areas are areas where light rays can pass. Both of these mask shapes require a calibration curve. Defects are classified by calculating the dimensional ratio of defects caught in both mask shapes. For a certain defect, if the dimensional ratio between the mask # 1 and the mask # 2 is close to 1, the defect is classified as a particle. However, if the dimensional ratio of the defect is larger than a certain number (for example, 1.15), it is classified as a micro scratch. If a defect is caught only by the mask of the form # 1 and not caught by the mask of the form # 2, it is classified as a CMP micro scratch. If a defect is caught only by the mask of the form # 2 and not caught by the mask of the form # 1, it is classified as a particle.
[0056]
Algorithm # 1 can also be executed in a multi-anode PMT. The advantage of this method is that only one scan is required. It is essentially the same as using two masks, but only one scan is required for data acquisition.
[0057]
Algorithm # 2, execution # 1, single channel, double polarization, oblique incidence, double scan
Algorithm # 2 uses two incident polarizations S and P. This method requires two scans. One is for S-polarized light and the other is for P-polarized light. Use PSL calibration curves for S and P polarization. The defect classification is performed by calculating the dimensional ratio of the defects captured in both the P and S scans. If the dimensional ratio of the P and S scans is close to 1, the defect is classified as a particle. However, if the dimensional ratio of the defect is other than 1 (eg, <0.65 or> 1.85 depending on the film thickness), the defect is classified as a micro scratch. In the case of a dielectric film, the intensity of interference with two polarized lights changes depending on the film thickness. The change in the intensity of the interference between the two polarizations is out of phase. That is, when the interference intensity of the P-polarized light is maximum, the interference intensity of the S-polarized light is minimum, or vice versa. Therefore, the dimension ratio of the CMP failure is determined to be larger or smaller than 1.0 depending on the thickness of the dielectric film. Similarly, if a defect is caught only in one polarization and not in the other, the defect is classified as a CMP microscratch or particle, depending on the film thickness. This method has been successfully demonstrated using oxidized CMP wafers. This method seems to give better results for metal films than for thick dielectric films, since thickness variations across the wafer are not a significant problem for metal films having substantial thickness. It is.
[0058]
In one experiment, the SP1 ™ instrument is calibrated using a PSL sphere and the particle size ratio of the intensity detected during the P and S scans is normalized to unity. Thus, in the presence of particles, the ratio will be 1 or about 1. Further, according to the histogram obtained from the instrument, the ratio of the intensity of the second set is concentrated to a value greater than 1, which is greater when illuminated with P-polarized light than when illuminated with S-polarized light. This indicates a set of failures in which scattering becomes larger. These are CMP defects such as micro-scratches, even if the scattering intensity is detected only during the P scan and not during the S scan. For the ratio is then infinite and therefore greater than one. The third set of ratios is at or near zero. These appear to be particles for the following reasons.
[0059]
Due to the interference effect on the surface detected upon irradiation with P or S polarized light, the detected scattering intensity is higher during P-scanning than during S-scanning, or vice versa. Thus, in the above experiment, if the scattering intensity detected by the interference effect on the surface is stronger during P-scanning than during S-scanning, particles of sufficient size in the region where S-polarized light is subject to structural interference Only will be present. This is shown, for example, in FIG. For example, referring to FIG. 14, when the film thickness on the wafer surface is 200 nanometers, from the curve of FIG. 14, the interference intensity on the wafer surface is higher when the P-polarized light beam is irradiated than when the S-polarized light beam is irradiated. Can be expected to be significantly stronger. However, in the case of particles of 300 nanometers or more, the scattering intensity detected during S scanning is significantly higher than during P scanning.
[0060]
<Surface roughness judgment>
In the case of an opaque film such as a metal or a transparent dielectric such as a dielectric having a low k value (both are spinned on a CVD deposited material), when there is almost no change in the film thickness, the haze measured from the film is obtained. Varies with the roughness of the film surface. Dielectric film CVD deposits for application to integrated circuits are almost uniform. Thus, measuring haze provides a quick alternative to measuring film roughness.
[0061]
Surface roughness can generally be measured with instruments such as the HRP® tool from KLA-Tenker Corporation of San Jose, Calif., And can be measured using atomic force microscopes, near field microscopes and scanning tunneling microscopes. And other types of scanning probe microscopes. This step is time consuming. Measuring film roughness more quickly than conventional methods by utilizing the above relationship between haze and film roughness in uniform dielectric films or in metals with varying uniformity Can be. Thus, according to FIG. 16, a high resolution profiler or AFM of KLA-Tenker Corporation is used to create a database of the correlation between haze and surface roughness using computer 310 for films of different thicknesses. The surface roughness of a representative film 302 of different thickness is measured using a tool 304 of the type SP1.^TBI Build a database by measuring haze values for these same films using system 10 or one of the integrated systems described above (eg, 100), or other tools that can measure haze. Can be. Since the surface roughness increases as the film thickness increases, it is preferable to measure similar films having various thicknesses. Then, the database can be shown in a line graph as shown in FIG. If it is desired to determine the surface roughness of the unknown film, the roughness is measured by measuring the haze of the film using an apparatus such as the system 10 shown in FIG. 1 or an integrated apparatus as described above. Can be determined by Then, using the measured value of the haze, a corresponding roughness value is selected from a database for a film whose thickness is already known from the graph shown in FIG. This allows the end user of the manufacturing facility to save up to one hour for each film because it only takes about one minute to measure the haze value and associate the haze measurement with the RMS roughness calibration curve of FIG. become able to.
[0062]
Although the invention has been described with reference to various embodiments, it will be understood that modifications and variations are possible without departing from the scope of the invention, which is limited only by the appended claims and equivalents thereof. Like. All of the references cited in this application are incorporated by reference in their entirety.
[Brief description of the drawings]
[0063]
FIG. 1 shows SP1 for explaining the present invention.^TBI 1 is a schematic diagram of a (trademark) system.
FIG. 2 is a schematic diagram illustrating a focused hollow conical light beam to illustrate one aspect of the present invention.
3A is a schematic diagram illustrating a possible arrangement of multi-fiber paths for carrying scattered light focused by the elliptical concentrator of the system of FIG. 1 to illustrate one aspect of the present invention.
3B is a schematic diagram of a multi-anode photoelectron tube (PMT) that can be used in connection with a multi-fiber path arrangement as shown in FIG. 3A to illustrate one aspect of the present invention.
FIG. 4 is a schematic illustration of a fiber path / multiplex detector arrangement for carrying scattered light focused by a lens concentrator in the narrow angle path of the system of FIG. 1 to illustrate one aspect of the present invention.
FIG. 5A is a cross-sectional view of a failure inspection system to illustrate a preferred embodiment of the present invention.
FIG. 5B is a cross-sectional view showing the arrangement of a separate optical path used in the embodiment shown in FIG. 5A.
FIG. 6A is a cross-sectional view of a failure inspection system to illustrate another embodiment of the present invention.
6B is a cross-sectional view showing the arrangement of the divided optical paths used in the embodiment shown in FIG. 6A.
FIG. 7 is a top view of a portion of a defect inspection system to illustrate another alternative embodiment of the present invention.
FIG. 8A is a schematic diagram of a multi-element detector in the embodiment of FIG.
FIG. 8B is a schematic diagram of a multi-element detector used in the embodiment of FIG.
FIG. 9A is a partial cross-sectional and partial perspective view of a failure inspection system to illustrate yet another alternative embodiment of the present invention.
9B is a schematic diagram of a filter wheel useful in the embodiment shown in FIG. 9A.
FIG. 9C is a schematic diagram of a filter wheel useful in the embodiment shown in FIG. 9A.
FIG. 10 is a schematic diagram illustrating two-dimensional diffraction components from a pattern on a surface of a test object to illustrate one aspect of the present invention.
FIG. 11 is a schematic diagram of a failure detection system to illustrate yet another alternative embodiment of the present invention.
FIG. 12 is a schematic diagram of an asymmetric mask used in different embodiments of the present invention.
FIG. 13A is a schematic illustration of two masks used in different systems of the present application to illustrate another aspect of the present invention.
FIG. 13B is a schematic illustration of two masks used in different systems of the present application to illustrate another aspect of the present invention.
FIG. 14 is a graph illustrating the interference intensity of the thin film surface when irradiated with light of three different polarizations to exemplify yet another aspect of the present invention.
FIG. 15 is a graph of haze and surface roughness to illustrate yet another aspect of the present invention.
16 is a block diagram illustrating a system for measuring surface roughness and haze of a representative film for collecting the database useful for the present invention shown in FIG.

Claims (62)

In surface inspection methods to detect abnormalities on the surface,
Scanning the surface with a light beam;
Focusing light rays scattered from the surface by a concentrator that focuses the scattered light substantially symmetrically with respect to a line perpendicular to the surface;
Stores information about the relative azimuthal position of the focused light relative to the line, and focuses the focused light onto the line or onto the line so that light scattered by surfaces at different azimuthal angles to the line is conveyed through different paths. Directing the focused light to paths at different azimuthal angles with respect to the corresponding direction, the directing step including separating the paths from each other by a separator to reduce crosstalk;
Converting the focused light carried by at least a portion of the path into respective signals representing rays scattered at different azimuthal angles with respect to the line;
Determining the presence or absence and / or characteristics of an abnormality inside or on the surface from the signal;
A surface inspection method comprising: The method of claim 1, wherein the step of directing comprises providing the focused light to an optical fiber that functions as a path. The method of claim 1, wherein the directing comprises reflecting a portion of the focused light at different azimuth angles from a reflective concentrator toward a path. The directing step includes providing a first portion of the focused light at different azimuths from the concentrator to the detector to produce a single output, and directing a second portion of the focused light from the concentrator to the path. The method of claim 1 including providing at different azimuths toward the azimuth. The method of claim 1, wherein the step of directing comprises providing a focused light substantially symmetrical to the line or direction toward a path. The method of claim 1, further comprising providing a path to be substantially symmetric about the line or direction. The step of directing the focused light to a detection unit of a multi-unit detector, wherein the units receiving the focused light are separated from each other by at least one detection unit to reduce crosstalk. 7. The method of claim 6, wherein: The step of converting converts the focused light from two or more diametrically opposed paths, and the method further comprises the two or more diametrically opposed paths. 7. The method according to claim 6, wherein the converted signals from are compared to detect micro-scratch on the surface. The method of claim 1, wherein said providing step comprises providing a path at an elevation angle away from any component expected to be scattered by the pattern on the surface. The method of claim 9, further comprising determining an elevation angle of a component expected to be scattered by the pattern from a dimension of the pattern. The method of claim 9, wherein the providing step provides a path substantially at an elevation angle of between about 5 and 9 degrees from the line or direction. The method of claim 9, wherein the component predicted to be scattered by the pattern is a Fourier component. Determining from the signal the number of Fourier components scattered by the regular pattern on the surface, discarding the number of signals associated with the number, and using the remaining signal to detect anomalies on the surface The method of claim 1, further comprising: In a surface inspection method for detecting anomalies on a surface having a diffraction pattern that scatters light rays,
Scanning the surface with a light beam;
Focusing light rays scattered from the surface by a concentrator that focuses the scattered light substantially symmetrically with respect to a line perpendicular to the surface;
Filtering at least a portion of the focused light with a spatial filter having an angular gap with an angle corresponding to the angular difference of the light components expected to be scattered by the pattern on the surface;
Determining the presence or absence of an abnormality inside or on the surface from the filtered focused light,
A surface inspection method comprising: The filtering step filters the focused light through two corresponding spatial filters, each having an angle gap therein, the gaps being offset from each other by an angle corresponding to the angular difference of the components expected to be scattered by the pattern on the surface. The method of claim 14, wherein: The method of claim 15, further comprising the step of splitting the focused light into first and second portions, wherein the filtering step filters the first and second portions by two corresponding spatial filters. Method. 16. The method of claim 15, wherein the angular difference of the component expected to be scattered by the pattern on the surface is greater than a certain value, and the gap and the deviation are substantially equal to the value. The method of claim 11, further comprising: outputting a signal in response to the filtered first and second portions of the focused light; and combining the signals to detect an anomaly inside or on the surface. Item 18. The method according to Item 17. The method of claim 14, wherein the component predicted to be scattered by the pattern is a Fourier component. In surface inspection equipment for detecting abnormalities on the surface,
A source for providing a light beam for scanning the surface;
A concentrator for focusing light rays scattered approximately symmetrically with respect to a line perpendicular to the surface from the surface,
An optical system including optical paths of different azimuthal angles with respect to the line or its corresponding direction, wherein the concentrator has a focused light path in the path to store information about a relative azimuthal position of the focused light with respect to the line. And the paths are arranged such that light rays scattered by surfaces at different azimuthal angles with respect to the lines are carried on different paths, and the optics move the paths together to reduce crosstalk. Including a separator to separate, further,
A plurality of detectors that convert the focused light carried by at least a portion of the path into respective signals representing rays scattered at different azimuthal angles with respect to the line;
A processor that determines whether there is an abnormality inside or on the surface from the signal,
A surface inspection apparatus comprising: 21. The apparatus of claim 20, wherein said optical system comprises an optical fiber, each of said fibers comprising a core and a cladding, said cladding being a separator. 21. The apparatus of claim 20, wherein the path is symmetrically arranged with respect to the line or direction. 21. The apparatus of claim 20, wherein the path is disposed at an elevation away from components expected to be scattered by the pattern. The apparatus according to claim 23, wherein the component predicted to be scattered by the pattern is a Fourier component. 21. The apparatus of claim 20, wherein the path is at an elevation substantially between about 5 and 9 degrees from the line or direction. The apparatus of claim 20, wherein the concentrator comprises a lens or a curved mirror. 27. The apparatus of claim 26, wherein the concentrator includes an elliptical or parabolic mirror. At least one stop is formed inside the mirror surface, and the device is further detected by at least one multi-unit detector for detecting light from a surface passing through the stop and the at least one detector. 28. The apparatus of claim 27, comprising at least one spatial filter for filtering light rays from the surface. 29. The apparatus of claim 28, wherein the at least one detector includes a detection unit that is substantially rectangular in shape, and wherein the at least one filter includes an array of opaque material strips. 29. The apparatus of claim 28, further comprising a rotatable member for supporting at least one filter, and a device for rotating the member. 31. The device of claim 30, wherein said member forms an S-polarizer therein. The device of claim 31, wherein the S-polarizer is substantially circular or semi-circular. The at least one filter includes a striped spatial filter for filtering light rays from the surface detected by the detector, and odd or even detection units shield from scattered light from the surface passing through their corresponding apertures. 31. The apparatus of claim 30, wherein the rotatable member supports a striped spatial filter. Two opposing diaphragms are formed inside the mirror surface, and the apparatus further comprises two opposing multi-unit detectors for respectively detecting light beams emitted from a surface passing through the corresponding diaphragms, and two masks. Wherein the detector comprises a detection unit having a substantially rectangular shape, each of the two masks covers every other detection unit of the corresponding detector, and the two masks comprise an odd number of detection devices. 28. The apparatus according to claim 27, wherein the apparatuses are arranged at positions shifted from each other. 35. The light beam of claim 34, wherein the light beam is at an oblique angle to a surface, and wherein the two stops are substantially centered at +90 [deg.] And 90 [deg.] Azimuth with respect to the light incident surface. apparatus. 21. The apparatus of claim 20, wherein the concentrator includes a lens having an axis substantially along the line or direction. The optical system may further include means for redirecting a portion of the focused light to the path, and the apparatus may further include a detector for detecting another portion of the focused light to produce a single output. 21. The device according to claim 20, wherein 38. The apparatus of claim 37, wherein said diverting means comprises a mirror or a beam splitter. In a surface inspection apparatus for detecting an abnormality on a surface having a diffraction pattern that scatters light rays,
A source for providing a light beam for scanning the surface;
A concentrator for focusing light rays scattered from the surface substantially symmetrically with respect to a line perpendicular to the surface,
A spatial filter for filtering at least a portion of the focused light, said filter having an angular gap of an angle corresponding to an angular difference expected to be scattered by a pattern on a surface;
A processor that determines whether there is an abnormality inside or on the surface from the filtered focused light,
A surface inspection apparatus comprising: The apparatus has first and second spatial filters for filtering first and second portions of the focused light, respectively, the two spatial filters each having an angle gap therein, and two spatial filters. 40. The apparatus of claim 39, wherein the gaps of the filters are offset from each other by an angle corresponding to an angular difference of a component expected to be scattered by a pattern on the surface. 41. The apparatus of claim 40, wherein the angular difference of the component expected to be scattered by the pattern on the surface is greater than a certain value, and the gap and the deviation are substantially equal to the value. 42. The processor of claim 41, wherein the processor outputs a signal in response to the filtered first and second portions of the focused light and combines the signals to detect an anomaly inside or on the surface. apparatus. 41. The apparatus of claim 40, further comprising a splitter for splitting the focused light into first and second portions filtered by two spatial filters. The apparatus of claim 39, wherein the component predicted to be scattered by the pattern is a Fourier component. A first near-vertical focusing device that emits light rays for scanning the surface, focuses light rays scattered by a surface area along a direction near a line perpendicular to the surface, and guides the light rays to a first detector; A second focusing device including a curved mirror surface having an axis symmetrical to said line that reflects and directs light scattered from a surface area along a direction away from the line toward a second detector. A surface inspection method for detecting an abnormality on a surface by employing an apparatus including:
Receiving a first output signal from a first detector in response to the light beam and scattered light from an area on the surface;
Receiving a second output signal from a second detector in response to the light beam and scattered light from an area on the surface;
Determining a ratio of the first and second output signals to determine whether the surface abnormality is microscratch or particle;
A surface inspection method comprising: Includes the step of injecting light in a diagonal direction to the surface. If the ratio is close to 1, it is determined that the abnormality is a particle, and if the ratio is lower than a predetermined ratio, it is determined to be a micro scratch. The method of claim 45, further comprising determining. 47. The method of claim 46, wherein said ratio is about 0.8. Impinging light in a direction oblique to the surface, wherein if the first output signal is not zero and the second output signal is substantially zero, it is determined that the abnormality is a particle; The method of claim 45, further comprising determining a microscratch if the one output signal is substantially zero and the second output signal is not zero. Includes the step of irradiating light in a direction substantially perpendicular to the surface. If the ratio is close to 1, it is determined that the abnormality is a particle. 46. The method of claim 45, further comprising determining a scratch. 50. The method of claim 49, wherein said value is about 1.6. Including injecting light in a direction substantially perpendicular to the surface, wherein if the first output signal is not zero and the second output signal is substantially zero, it is determined that the abnormality is micro-scratch. 46. The method of claim 45, further comprising determining that the particle is a particle if the first output signal is substantially zero and the second output signal is not zero. Employing a curved mirror with an axis symmetrical to said line that reflects and guides light scattered from a surface area along the direction away from the line toward a second detector to eliminate anomalies on the surface In the surface inspection method to detect,
Directing light in a direction oblique to the surface to scan the surface;
A light beam scattered by the surface along the forward scattering direction is focused separately from the other scattering directions, the separately focused light beam is separately detected, and a first signal representing the focused forward scattered light is provided; Outputting a second signal representing focused scattered light other than light;
Comparing the two signals to determine whether the surface abnormality is micro scratch or particle;
A surface inspection method comprising: The comparing step is a step of comparing the ratio of the two signals to 1, and if the ratio is close to 1, the abnormality is called a particle, and the ratio between the first signal and the second signal is a predetermined value. 53. If so, a step called microscratching. The comparing step includes the step of calling the anomaly a microscratch if the first signal is not zero and the second signal is substantially zero; otherwise, calling it a particle. 53. The method of claim 52, wherein the method comprises: 53. The method of claim 52, wherein the further focusing is performed by directing scattered light along another optical path separated from the other by the separator. The further focusing is performed by blocking the forward scattering direction or blocking all scattering directions other than the forward scattering direction and guiding the scattered light through a spatial filter in the form of a mask. 52. The method of claim 52. Employing a curved mirror with an axis symmetrical to said line that reflects and guides light scattered from a surface area along the direction away from the line toward a second detector to eliminate anomalies on the surface In the surface inspection method to detect,
Light of a first polarization state and light of a second polarization state are sequentially incident on the surface in an oblique direction to scan the surface, wherein the first and second states are different. ,
A first signal comprising a pair of signals, namely a signal representing the scattered light focused when the surface is scanned with light in a first polarization state, focusing the light scattered by the defect during successive scans; Outputting a second signal including a signal representing the scattered light focused when the surface is scanned with light in a second polarization state;
Comparing the two signals to determine whether the surface abnormality is micro scratch or particle;
A surface inspection method comprising: The method of claim 57, wherein the comparing comprises deriving a ratio of the signals to determine a ratio, and comparing the ratio to a predetermined reference value. The method of claim 57, wherein the first and second polarization states are S-polarization and P-polarization states. In a method for determining surface roughness,
Creating a database relating the haze value to the surface roughness of the thin film;
Measuring the haze value of the surface;
Determining a surface roughness value from the haze value and the database;
A method comprising: The creating step includes:
Measuring the haze value of the surface of the representative thin film;
Measuring the value of the surface roughness;
Collecting the database;
61. The method of claim 60, comprising: 62. The method of claim 61, wherein measuring the roughness value is performed with a profilometer or a scanning probe microscope.

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