WO2004019389A1 - Dispositif et procede servant a detecter la position d'une marque, dispositif et procede servant a mesurer une superposition - Google Patents

Dispositif et procede servant a detecter la position d'une marque, dispositif et procede servant a mesurer une superposition Download PDF

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Publication number
WO2004019389A1
WO2004019389A1 PCT/JP2003/010582 JP0310582W WO2004019389A1 WO 2004019389 A1 WO2004019389 A1 WO 2004019389A1 JP 0310582 W JP0310582 W JP 0310582W WO 2004019389 A1 WO2004019389 A1 WO 2004019389A1
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WIPO (PCT)
Prior art keywords
mark
waveform
edge signal
edge
calculating
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PCT/JP2003/010582
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English (en)
Japanese (ja)
Inventor
Hiroshi Aoki
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Nikon Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Nikon Corporation filed Critical Nikon Corporation
Priority to AU2003264338A priority Critical patent/AU2003264338A1/en
Publication of WO2004019389A1 publication Critical patent/WO2004019389A1/fr

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7092—Signal processing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7073—Alignment marks and their environment
    • G03F9/7084—Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels

Definitions

  • Mark position detecting device Description Mark position detecting device, mark position detecting method, overlay measuring device, and overlay measuring method
  • the present invention relates to a mark position detecting device for detecting the position of a test mark on a substrate, a mark position detecting method, an overlay measuring device, and an overlay measuring method.
  • the present invention relates to a mark position detection device suitable for position detection and the like. Background art
  • an exposure process of printing a circuit pattern formed on a mask (reticle) on a resist film, and a developing process of dissolving an exposed portion or an unexposed portion of the resist film are included.
  • the circuit pattern (resist pattern) is transferred to the resist film, and the resist pattern is used as a mask to perform etching or vapor deposition (processing step), thereby forming a predetermined pattern immediately adjacent to the resist film.
  • the circuit pattern is transferred to the material film (pattern forming step).
  • circuit patterns of various material films are laminated on a substrate (semiconductor wafer or liquid crystal substrate), and the circuit of a semiconductor element or a liquid crystal display element is formed. Is formed.
  • the alignment between the mask and the substrate This is an alignment between the circuit pattern and the circuit pattern formed on the substrate in the previous pattern forming step, and is performed using an alignment mark indicating a reference position of each circuit pattern.
  • Inspection of the superposition state of the resist pattern on the substrate is performed by superimposing the resist pattern on the circuit pattern (hereinafter referred to as “base pattern”) formed in the previous pattern formation step.
  • base pattern the circuit pattern formed in the previous pattern formation step.
  • This is an alignment detection, which is performed using an overlay mark indicating a reference position of each of the base pattern and the resist pattern.
  • the test marks are positioned within the field of view of the apparatus, and are detected using an image sensor such as a CCD camera. An image of the inspection mark is taken, and the detection is performed based on an edge signal among the obtained image signals.
  • the image signal represents a distribution relating to a luminance value for each pixel on the imaging surface of the imaging element.
  • the edge signal is a sudden change in the luminance value of the image signal.
  • a well-known algorithm called a correlation method is used.
  • the correlation method since the correlation operation is performed using the entire edge signal waveform, it is hardly affected by signal noise, and the position of the test mark can be calculated with good reproducibility.
  • the correlation method is an algorithm on the assumption that the waveform of the edge signal is symmetric. For this reason, when the symmetry of the waveform of the edge signal is reduced, an error increases when calculating the position of the test mark. That is, the position of the test mark cannot be accurately detected.
  • the symmetry of the waveform of the edge signal may be reduced even when the shape of the edge pair of the test mark is symmetrical. Disclosure of the invention
  • An object of the present invention is to provide a mark position detecting device, a mark position detecting method, a mark position detecting method, an overlay measuring device, which can accurately detect the position of a test mark even if the waveform of an edge signal relating to an edge pair of the test mark is asymmetric. And to provide an overlay measurement method.
  • the mark position detecting device of the present invention includes one or more edge pairs formed on a substrate.
  • Illuminating means for illuminating the test mark; imaging means for capturing an image based on light from the test mark and outputting an image signal composed of a plurality of sample points; and a sudden change in the luminance value of the image signal
  • a detecting means for detecting a center position of the test mark based on the edge signal, wherein the detecting means comprises: A correction unit that corrects the asymmetry of the edge signal by removing one or more of the sample points included in the edge signal; a waveform based on the edge signal corrected by the correction unit; Calculating means for calculating the center position by calculating a maximum correlation value in a correlation function with a waveform obtained by folding back.
  • the waveform of the edge signal after the asymmetry has been corrected by the correcting means (that is, a symmetrical waveform) is used, so that the position of the test mark can be detected with high accuracy.
  • Another mark position detection device of the present invention includes: an illumination unit that illuminates a test mark including one or more edge pairs formed on a substrate; and an image based on light from the test mark.
  • the mark position detection device uses a calculation waveform (ie, a symmetrical waveform) having the largest correlation function maximum correlation value among a plurality of different calculation waveforms, the position of the test mark is accurately detected. be able to.
  • a calculation waveform ie, a symmetrical waveform
  • the detection unit may be configured to perform the correction before the correction.
  • Comparing means for comparing the maximum correlation value calculated by the first calculating means with a predetermined threshold value using the calculation waveform based on the edge signal, wherein the correcting means As a result, when the maximum correlation value based on the uncorrected edge signal is smaller than the threshold value, the edge signal is corrected.
  • a mark position detection method includes: an illumination step of illuminating a test mark including one or more edge pairs formed on a substrate; and capturing an image based on light from the test mark.
  • a detection step for detecting the center position of the edge signal wherein the detecting step corrects the asymmetry of the edge signal by removing one or more of the sample points included in the edge signal. Calculating a maximum correlation value in a correlation function between a correction step, a waveform based on the edge signal after the correction in the correction step, and a waveform obtained by folding the waveform. And calculating the center position.
  • the waveform of the edge signal after the asymmetry has been corrected in the correction step (that is, a symmetrical waveform) is used, so that the position of the mark to be detected can be detected accurately.
  • Another mark position detection method of the present invention includes: an illumination step of illuminating a test mark including one or more edge pairs formed on a substrate; capturing an image based on light from the test mark; An imaging step of outputting an image signal composed of sample points of the following; an extraction step of extracting a rapidly changing portion of a luminance value from the image signal as an edge signal relating to the edge pair; A detection step of detecting a center position of a detection mark, wherein the detection step corrects the edge signal by removing one or more sample points included in the edge signal.
  • a first calculation step of calculating a value, most magnitude among the plurality of the maximum correlation value calculated by the first calculation step with each of a plurality of different said operational waveform And a second calculating step of calculating the center position based on the one maximum correlation value selected in the selecting step.
  • the operation waveform having the largest correlation function maximum correlation value that is, a symmetrical waveform
  • the position of the target mark is accurately detected. be able to.
  • the maximum correlation value calculated in the first calculating step using the calculation waveform based on the uncorrected edge signal is determined in advance.
  • An overlay measurement apparatus is an overlay measurement apparatus for inspecting an overlay state of a plurality of patterns formed on a substrate, wherein a center position of a test mark indicating a reference position of each of the plurality of patterns is determined.
  • a mark position detecting device for detecting each of the mark positions; and a measuring means for measuring an amount of misalignment of the plurality of patterns based on a difference between the respective center positions detected by the mark position detecting device. Things.
  • An overlay measurement method is directed to an overlay measurement method for detecting an overlay state of a plurality of patterns formed on a substrate by using the above mark position detection method. Detecting a center position of a test mark indicating a reference position of each of the patterns, and superimposing the plurality of patterns based on a difference between the respective center positions detected in the detection step. The method further includes a measuring step of measuring a shift amount.
  • FIG. 1 is a diagram showing the overall configuration of the overlay measurement device 10.
  • FIG. 2 is a plan view (a) of the overlay mark 30 formed on the wafer 11 and diagrams (b :) to (d) illustrating images in the observation area.
  • FIG. 3 is a diagram showing an example of a representative waveform (a) and a waveform (b) of an edge signal in a standard overlay mark 30.
  • FIG. 4 is a diagram showing an example of a representative waveform (a) and a waveform (b) of an edge signal in a standard overlay mark 30.
  • FIG. 5 is a diagram showing an example of a representative waveform (a) and a waveform (b) of an edge signal in the superimposition mark 30 in the proximity state.
  • FIG. 6 is a diagram showing an example of the representative waveform (a) and the waveform (b) of the edge signal in the superimposition mark 30 in the proximity state.
  • FIG. 7 is a flowchart showing a procedure of position detection in the overlay measurement device 10.
  • FIG. 8 is a diagram illustrating a waveform example of an edge signal after the symmetry is improved.
  • FIG. 9 is a diagram for explaining an improvement in symmetry and an improvement in detection accuracy.
  • FIG. 10 is a diagram showing an overlay mark (a) having a large size difference between the frame mark and the box mark and a small overlay mark (b).
  • the overlay measurement apparatus 10 includes a detection stage 12 that supports the wafer 11 and an illumination optical system (13 to 13) that emits illumination light L1 toward the wafer 11 side. 1
  • an imaging optical system (16, 17) for forming an image of the wafer 11 for forming an image of the wafer 11
  • a CCD image sensor 18 for forming an image of the wafer 11
  • the wafer 11 (base Plate).
  • the wafer 11 On the wafer 11, a plurality of circuit patterns (all not shown) are laminated on the surface.
  • the uppermost circuit pattern is the resist pattern transferred to the resist film.
  • the wafer 11 is in the process of forming another circuit pattern on the underlying pattern formed in the previous pattern forming process (exposure to the resist film, etching of the material film, and etching of the material film). Before).
  • FIG. 2 (a) is a plan view of the overlay mark 30.
  • the overlay mark 30 is composed of an outer frame mark 31 and an inner box mark 32, and one of the frame mark 31 and the box mark 32 is a base mark and the other is a resist mark.
  • the base mark and the resist mark are formed simultaneously with the base pattern and the resist pattern, respectively, and indicate the reference positions of the base pattern and the resist pattern.
  • the frame mark 31 includes two edge pairs E 1 and, 2 in the X direction.
  • One edge pair ⁇ 1 is composed of a left edge E 1 (L) and a right edge ⁇ 1 (R), and the other edge pair E 2 is a left edge E 2 (L) and a right edge.
  • E 2 (R) That is, the frame mark 31 has two edges E 1 (L) and E 2 (L) on the left side and two edges E 1 (R) and E 2 (R) on the right side. The same applies to the Y direction of the frame mark 31.
  • the box mark 32 includes one edge pair E 3 in the X direction.
  • the edge pair E 3 is composed of a left edge E 3 (L) and a right edge E 3 (R). That is, the box mark 32 has one edge E 3 (L) on the left side and one edge E 3 (R) on the right side.
  • the frame mark 31 and the box mark 32 respectively correspond to the “test mark” in the claims.
  • a material film to be processed is formed between the resist mark and the resist pattern, and the base mark and the base pattern.
  • the inspection stage 12 of the overlay measurement device 10 holds the wafer 11 in a horizontal state and can be moved to an arbitrary position in a horizontal plane.
  • the observation area including the overlay mark 30 (FIG. 2 (a)) of the wafer 11 is positioned within the field of view of the imaging optical system (16, 17).
  • the normal direction of the inspection stage 12 is the Z direction, and the mounting surface of the wafer 11 is the XY surface.
  • the illumination optical system (13 to 15) is composed of a light source 13, an illumination lens 14, and a prism 15, and the prism 15 is on the optical axis O2 of the imaging optical system (16, 17). Placed in The optical axis ⁇ 2 of the imaging optical system (16, 17) is parallel to the Z direction. The reflection / transmission surface 15 a of the prism 15 is inclined at approximately 45 ° with respect to the optical axis O 2. The optical axis O l of the illumination optical system (1 3-1 5) is perpendicular to the optical axis O 2 of the imaging optical system (16, 17).
  • the imaging optical system (16, 17) is an optical microscope section composed of an objective lens 16 and an imaging lens 17, and the objective lens 16 is connected between the detection stage 12 and the prism 15 Placed between.
  • the imaging lens 17 is an optical element that functions as a second objective lens, and is disposed on the opposite side of the prism 15 from the objective lens 16.
  • the light emitted from the light source 13 is guided to the prism 15 via the illumination lens 14, and After being reflected by the reflection transmitting surface 15a (illumination light L1), it is guided to the objective lens 16 side. After passing through the objective lens 16 (illumination light L 2), the light enters the wafer 11 on the inspection stage 12. At this time, the observation area of the wafer 11 is almost vertically illuminated by the illumination light L2.
  • reflected light L3 is generated according to the uneven structure (overlap mark 30) there.
  • the reflected light L 3 is guided to the imaging lens 17 via the objective lens 16 and the prism 15, and the imaging surface of the CCD imaging device 18 is operated by the action of the objective lens 16 and the imaging lens 17.
  • Image on top Is done.
  • an enlarged image (reflection image) based on the reflected light L3 is formed on the imaging surface of the CCD imaging device 18.
  • the CCD image sensor 18 is an area sensor in which a plurality of pixels are two-dimensionally arranged, captures a reflection image on an imaging surface, and outputs an image signal to the image processing device 19.
  • the image signal is composed of a plurality of sample points, and represents a distribution (luminance distribution) relating to the luminance value of each pixel on the imaging surface of the CCD imaging device 18.
  • the above-mentioned illumination optical system (13 to 15) and the objective lens 16 correspond to the “illuminating means” in the claims.
  • the imaging optical system (16, 17) and the CCD imaging device 18 correspond to the "imaging means” in the claims.
  • the image processing device 19 corresponds to “extraction means” and “detection means” in the claims.
  • the image processing device 19 captures, as an image, a reflection image of the observation area (including the overlay mark 30) of the wafer 11 based on the image signal from the CCD image sensor 18.
  • the image of the observation region of the wafer 11 includes three edge images F 1 (L), F 2 (L), F 3 (L) appears, and three edge images F 1 (R), F 2 (R), and F 3 (R) appear on the right side.
  • the inner two edge images F 3 (L) and F 3 (R) correspond to the edges E 3 (L) and E 3 (R) of the concavo-convex structure of the box mark 32 shown in FIG. The corresponding image.
  • the remaining four edge images F 1 (L), F 2 (L), F 1 (R), and F 2 (R) are the edges E 1 (L), E 2 ( L), E1 (R), and E2 (R).
  • the image processing apparatus 19 outputs the box image of the six edge images F 1 (L), F 2 (L),... (FIG. 2 (b)) appearing in the image of the observation area of the wafer 11.
  • the edge images F 3 (L) and F 3 (R) related to the mark 3 2 the center position C 2 of the box mark 32 in the X direction is detected, and the edge image F 1 (L) related to the frame mark 31 is detected.
  • F 2 (L), F 1 (R), and F 2 (R) the center position C 1 of the frame mark 31 in the X direction is detected.
  • the image processing device 19 Prior to detecting the center positions C 1 and C 2, the image processing device 19 integrates the image signals captured from the CCD image sensor 18 (projection processing). That is, the image signals are integrated along the direction (Y direction) perpendicular to the detection direction (X direction) of the center positions C1 and C2. This is a process for reducing signal noise.
  • the waveform of the integrated image signal generated by the projection process is called a “representative waveform”.
  • the horizontal axis in FIGS. 3 to 6 represents the position of each sample point (pixel) of the representative waveform, and the vertical axis represents the luminance value.
  • the vicinity of the poton where the luminance value of the representative waveform is minimal is the edge images F1 (L), F2 (L), F3 (L), F1 (R ), F 2 (R) and F 3 (R).
  • FIG. 3 (a) and FIG. 4 (a) show a standard superposition mark 30 having a large size difference between the frame mark 31 and the box mark 32 as shown in FIG. 10 (a).
  • Fig. 3 (a) shows an example of a representative waveform.
  • Fig. 4 (a) shows the center positions C1, C2 when the deviation between the center positions C1, C2 of the frame mark 31 and the box mark 32 is small. This relates to the case where the deviation is large.
  • FIGS. 5A and 6A are both examples of representative waveforms at the superposition mark 30 having a small size difference between the frame mark 31 and the potas mark 32 as shown in FIG. 10B.
  • Fig. 5 (a) shows the case where the deviation between the center positions C1 and C2 of the frame mark 31 and the box mark 3 2 is small
  • Fig. 6 (a) shows the case where the deviation between the center positions C1 and C2 is large.
  • FIG. 6A the edge images F 2 (L) and F 2 (R) due to the frame mark 31 and the edge images F 3 (L) and F 3 due to the box mark 32 are shown. (R) and the force S are separated to some extent on the left side of the figure, but are very close on the right side of the figure.
  • the left boundary portion 4 1 (L) corresponding to between the frame mark 3 1 and the box mark 3 2 has a constant luminance value A
  • the right boundary portion 41 (R ) Is a value B whose brightness value is smaller than a constant value A.
  • the balance between left and right (symmetry) is broken. This is due to the proximity of the frame mark 3 1 and the box mark 3 2.
  • the range 34 in FIG. 2 (c) is a range including two edge images F 3 (L) and F 3 (R) related to the box mark 32 appearing in the image of the observation region. Set when detecting the center position C2 of mark 32. Then, a representative waveform (not shown) is generated by integrating the image signals within this range 34, and the obtained representative waveform is used for detecting the center position C 2.
  • the range 35 in FIG. 2D is a range including four edge images F 1 (L), F 2 (L), F 1 (R), and F 2 (R) related to the frame mark 31. This is set when the center position C 1 of the frame mark 31 is detected. Then, a representative waveform (not shown) is generated by integrating the image signals within this range 35, and the obtained representative waveform is used for detecting the center position C1.
  • an observation area including the overlay mark 30 (FIG. 2 (a)) of the wafer 11 is positioned in the field of view of the overlay measurement device 10.
  • CCD imaging On the imaging surface of the element 18, a reflection image of the overlay mark 30 is formed. Therefore, the image processing device 19 can capture the reflection image of the superposition mark 30 as an image (see FIG. 2 (c)) based on the image signal from the CCD image sensor 18.
  • the image processing device 19 sets a range including two edge images F 3 (L) and F 3 (R) related to the box mark 32. Then, a representative waveform (not shown, see (a) in FIGS. 3 to 6) is generated by integrating the image signals in the Y direction within this range 34 (step S1 in FIG. 7). Setting range 34 can be done manually or automatically. '
  • the image processing device 19 extracts a portion where the luminance value changes abruptly from the image signal as an edge signal based on the representative waveform generated in step S1 (step S2).
  • the edge signal is a signal related to the edge pair E 3 of the box mark 32 (FIG. 2 (a)).
  • the extraction of the edge signal is automatically performed according to, for example, the following procedures (1) to (6).
  • the brightness value of the sample point S2 has a constant value A in FIGS. 3 to 5 (a), but has a value B which is smaller than the value A in FIG.
  • the waveform 42 of the extracted edge signal has a shape as shown in (b) of FIGS.
  • the luminance value at the left end and the right end of the waveform 42 both have the same value A. Therefore, the waveforms 42 in FIGS. 3 to 5B are symmetrical.
  • the waveforms 42 in FIGS. 3 to 5B are symmetrical.
  • the waveform in Fig. 6 (b) the waveform
  • the luminance values at the left end and the right end of 4 2 have different values ⁇ and ⁇ due to the proximity of the frame mark 3 1 and the box mark 3 2. For this reason, the waveform 42 in FIG. 6 (b) is bilaterally asymmetric.
  • the box mark 3 The center position C 2 of 2 is detected. This procedure is equally accurate whether the edge signal waveform 42 is symmetrical as shown in (b) of Figs. 3 to 5 or asymmetrical as shown in (b) of Fig. 6. It can perform position detection.
  • step S3 the image processing device 19 determines a waveform for calculation.
  • the waveform 42 of the edge signal extracted in step S2 is used as the calculation waveform.
  • the image processing device 19 sets a temporary center position of the waveform 42 (step S4).
  • the image processing device 19 folds the waveform 42 at the temporary center position, and calculates a correlation function between the obtained folded waveform and the original waveform 42 (step S5).
  • a correlation function is calculated using a well-known algorithm called a correlation method while relatively offsetting the folded waveform and the original waveform 42.
  • the correlation function indicates the relationship between the offset amount between the folded waveform and the original waveform 42 and the correlation value at that time.
  • the correlation value takes a value from “0 to 1”.
  • the image processing apparatus 19 obtains the maximum correlation value in the correlation function calculated in step S5, and selects the offset amount ⁇ corresponding to the maximum correlation value (step S6). Because this is the first time (Yes in step S7),
  • step S6 Performs the processing of 8. That is, a magnitude comparison between the maximum correlation value obtained in step S6 and a predetermined threshold value (for example, 0.95) is performed.
  • the maximum correlation value is an index indicating the left-right symmetry of the calculation waveform.
  • step S8 is No
  • the threshold value for example, 0.95
  • step S10 a data table indicating the relationship between the candidate for the center position C2 calculated in step S9 and the maximum correlation value obtained in step S6 is created (step S10). If the image processing device 19 repeatedly executes the above-described calculation of the candidate for the center position C2 (No in step S11), the image processing device 19 performs the processing in the next step S12,
  • step S12 one or more sample points are removed from the edge signal extracted in step S2 (the left-right asymmetrical waveform 42 in FIG. 6B), and the edge signal is corrected.
  • the position and number of sample points to be removed are arbitrary. For example, it is conceivable to remove one sample point located at the left end or right end of the edge signal (asymmetrical waveform 42 in Fig. 6 (b)).
  • the image processing apparatus 19 returns to the processing in step S3 and executes the second processing (S3 to S1'1). This time (second time), in the process of step S3, the waveform of the edge signal after the correction in step S12 becomes the waveform for calculation.
  • steps S4 to S6 are executed using the waveform for calculation (the waveform of the edge signal after correction), and the maximum correlation value in the correlation function is obtained, and the offset amount ⁇ corresponding to the maximum correlation value is selected. I do. Because this is the second time, If the step S7 is No), the process proceeds to the step S9 without executing the processing of the step S8, and a new candidate of the center position C2 of the box mark 32 is calculated. Then, the relationship between the new candidate and the maximum correlation value obtained in step S6 is added to the data table (step S10).
  • step S 12 edge signal correction processing
  • the removal position and the removal number of the sample point are determined. If it is changed, candidates for the center position C 2 based on a plurality of different calculation waveforms can be calculated one after another.
  • the sample point to be removed may be specified by the operator or automatically set by the apparatus.
  • step S11 force SYes After finishing the calculation of the candidate for the center position C2 (step S11 force SYes), the image processing device 19 proceeds to the next step S13. At this time, a data table indicating the relationship between the plurality of candidates for the center position C2 and the maximum correlation value has been completed in the image processing device 19.
  • the image processing device 19 selects one of the plurality of candidates for the center position C2 with reference to the data table (step S13). That is, a candidate corresponding to one having the largest value among the plurality of maximum correlation values (the maximum value of the maximum correlation values) is searched for, and this candidate is selected as the "center position C2". This is because the greater the maximum correlation value, the higher the left-right symmetry of the operation waveform and the more accurate the detection result. For example, if the waveform of the edge signal (the edge signal before correction) extracted in step S2 has a left-right asymmetry like the waveform 42 shown in FIG. 6B, the “center position” is determined in step S13. The candidate selected as C 2 "is a case where the waveform 43 shown in FIG. 8 is used as the calculation waveform.
  • This waveform 43 is obtained by removing the four sample points on the left end and one sample point on the right end of the sample points of the waveform 42 (Fig. 6 (b)), as can be seen from Fig. 8. Symmetrical waveform.
  • the maximum correlation value in this waveform 43 is “0.97” as shown in FIG. 9, which is improved by “0.3 2” compared to the maximum correlation value “0.65” in the waveform 42 of the edge signal before correction. You can see that.
  • the difference between the center position C2 calculated using the corrected left-right symmetrical waveform 43 and the candidate of the center position C2 calculated using the left-right asymmetrical waveform 42 before the correction represents the improvement in detection accuracy.
  • the measurement error of the center position of the inner mark could be reduced by about 19 nm.
  • the center position C 1 of the frame mark 31 can be detected with high accuracy. For example, if the waveform of the edge signal (the edge signal before correction) extracted in step S2 has left-right asymmetry like the waveforms 44 and 45 shown in FIG.
  • the candidate selected as the center position C2 " is a case where the waveforms 46 and 47 shown in FIG.
  • waveform 46 is obtained by removing the four sample points on the right end from the sample points of waveform 44 (Fig. 6 (b)), and waveform 47 is the waveform 45 (Fig. 6 (b)).
  • waveform 47 is the waveform 45 (Fig. 6 (b)).
  • One of the sample points on the left side is removed.
  • the waveforms 46 and 47 are left-right symmetrical waveforms as can be seen from FIG.
  • the maximum correlation value of these waveforms 46 and 47 is “0.98” as shown in FIG. 9.
  • “0.16” It can be seen that only improved.
  • the difference between the center position C 1 calculated using the left-right symmetric waveforms 46 and 47 after correction and the candidate of the center position C 1 calculated using the left-right asymmetric waveforms 44 and 45 before correction indicates the improvement in detection accuracy. In other words, removing the sample points reduced the measurement error by about 13 nm.
  • the image processing apparatus 19 performs an overlay inspection of the wafer 11 (inspection of an overlay state of the resist pattern with respect to the underlying pattern). That is, Based on the difference between the center positions C 1 and C 2 of the memory mark 31 and the box mark 32, an overlay displacement amount R (FIG. 2 (a)) is calculated.
  • the overlay displacement amount R is expressed as a two-dimensional vector of the surface of the wafer 11.
  • the overlay deviation amount R can also be detected with high accuracy.
  • the removal of the sample points improved the overlay displacement R by about 32 nm. In other words, the measurement error was reduced by about 32 nm.
  • the correlation calculation (calculation of the correlation function between the calculation waveform and the folded waveform) is performed using the entire calculation waveform determined in step S3, it is hardly affected by signal noise.
  • the center positions C 1 and C 2 of the frame mark 31 and the box mark 32 can be calculated with good reproducibility.
  • the overlay deviation R can be calculated with good reproducibility.
  • the number of removed sample points in the edge signal correction processing (S12) be minimized.
  • the reason for this is that the greater the number of sample points removed, the narrower the range of the operation waveform (the smaller the number of sample points), and the more likely it is to be affected by signal noise.
  • step S8 the magnitude of the maximum correlation value is compared with a predetermined threshold (for example, 0.95), and only when the maximum correlation value is smaller, although the sample points have been removed, the sample points may be removed in all cases, regardless of the maximum correlation value obtained in the first correlation operation. This corresponds to omitting the processing of steps S7, S8 and S14 in the flowchart of FIG.
  • a predetermined threshold for example 0.95
  • the image processing device 19 in the overlay measurement device 10 removes the sample points of the edge signal and detects the center positions C 1 and C 2. The same effect can be obtained even when an external computer connected to 10 is used.
  • the overlay measurement apparatus 10 has been described as an example, but the present invention is not limited to this.
  • alignment between the mask and the wafer 11 is performed before the exposure step in which the circuit pattern formed on the mask is printed on the resist film. It can also be applied to equipment (alignment system of exposure equipment). In this case, the position of the alignment mark formed on the wafer 11 can be accurately detected.
  • the present invention is also applicable to a device that detects an optical displacement between a single test mark and a reference position of a camera. Industrial potential

Abstract

Au moment de la détection de la position d'une marque sur un substrat, il est possible de détecter avec précision cette position, même si une onde d'un signal périphérique associée à la paire périphérique de la marque est asymétrique. Dans un dispositif de traitement d'image (19), un ou plusieurs points d'échantillonnage contenus dans le signal périphérique sont supprimés de manière à corriger l'asymétrie de ce signal. D'après le signal périphérique après correction, un oscillogramme de calcul d'une corrélation est défini, puis replié, la valeur de corrélation maximum de la fonction de corrélation par rapport à l'oscillogramme replié étant calculé, ce qui permet de calculer la position centrale de la marque.
PCT/JP2003/010582 2002-08-22 2003-08-21 Dispositif et procede servant a detecter la position d'une marque, dispositif et procede servant a mesurer une superposition WO2004019389A1 (fr)

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AU2003264338A AU2003264338A1 (en) 2002-08-22 2003-08-21 Mark position detection device, mark position detection method, superimposing measurement device, and superimposing measurement method

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JP2002-242049 2002-08-22
JP2002242049A JP4178875B2 (ja) 2002-08-22 2002-08-22 マーク位置検出装置、マーク位置検出方法、重ね合わせ測定装置、および、重ね合わせ測定方法

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TWI762417B (zh) * 2021-09-01 2022-04-21 環球晶圓股份有限公司 識別晶圓的方法

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JP2005302970A (ja) * 2004-04-09 2005-10-27 Nikon Corp レシピ作成方法、位置検出装置、および、位置ずれ検出装置
JP2006118931A (ja) * 2004-10-20 2006-05-11 Nikon Corp マーク位置検出装置および位置ずれ検出装置
JP4757701B2 (ja) * 2006-04-25 2011-08-24 Ｊｕｋｉ株式会社 電子部品の吸着位置補正方法及び装置
JP4770590B2 (ja) 2006-05-26 2011-09-14 ソニー株式会社 アウトラインの作成装置および作成方法、並びに画像処理装置

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JPH0894315A (ja) * 1994-09-28 1996-04-12 Canon Inc 位置合わせ方法、該方法による投影露光装置および位置ズレ計測装置
JPH104044A (ja) * 1996-06-13 1998-01-06 Hitachi Ltd パターン検出方法ならびにアライメントマーク検出方法およびそれを用いた光学装置
WO2000057126A1 (fr) * 1999-03-24 2000-09-28 Nikon Corporation Dispositifs et procedes de determination de position, d'exposition, et de determination d'alignement
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JPH0894315A (ja) * 1994-09-28 1996-04-12 Canon Inc 位置合わせ方法、該方法による投影露光装置および位置ズレ計測装置
JPH104044A (ja) * 1996-06-13 1998-01-06 Hitachi Ltd パターン検出方法ならびにアライメントマーク検出方法およびそれを用いた光学装置
WO2000057126A1 (fr) * 1999-03-24 2000-09-28 Nikon Corporation Dispositifs et procedes de determination de position, d'exposition, et de determination d'alignement
JP2000275010A (ja) * 1999-03-26 2000-10-06 Canon Inc 位置計測方法および該位置計測法を用いた半導体露光装置

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI762417B (zh) * 2021-09-01 2022-04-21 環球晶圓股份有限公司 識別晶圓的方法

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