Correction method of overlay measurement device and correction system of overlay measurement device

Abstract

The present invention relates to a method for correcting an overlay measurement error. A correction method of an overlay measurement device, according to one embodiment of the present invention, may comprise the steps of: (a) calculating primary data indicating changes in TIS values of a plurality of targets, and calculating the pinhole value at the position where dispersion is the smallest as a primary correction position; (b) calculating secondary data by moving the pinhole a predetermined distance from the primary correction position, and calculating the pinhole value at the position where dispersion is the smallest as a secondary correction position; (c) calculating the average value of the TIS values at the secondary correction position, and calculating the pinhole positions of the average value as respective correction values of the plurality of targets; and (d) storing the correction values in an automatic measurement program.

Description

Calibration method for overlay measuring device and calibration system for overlay measuring device

[0001] The present invention relates to the calibration of an overlay measurement device for a wafer, and more particularly, to a calibration method for an overlay measurement device and a calibration system for an overlay measurement device.

[0002] Generally, as technology advances, semiconductor devices are shrinking in size and integrated circuit density is increasing. Forming these integrated circuits on a wafer requires numerous manufacturing processes to sequentially form the desired circuit structures and elements at specific locations. These manufacturing processes sequentially create patterned layers on the wafer.

[0003] Through these repeated layering processes, electrically active patterns are created within the integrated circuit. If the individual structures are not aligned within the tolerances allowed by the production process, interference between the electrically active patterns can occur, potentially affecting the performance and reliability of the manufactured circuit.

[0004] Accordingly, pattern alignment errors between layers are measured and verified using a measuring device, and the focal point is located through contrast or phase difference in the target image of the wafer for measurement and verification. At this time, after the wafer is placed on a stage to measure the patterns formed on each layer of the wafer, patterns formed at various locations on the wafer's upper surface are detected.

[0005] However, the optical system for detecting the pattern formed on the top of the wafer has optical errors due to structural optical alignment or environmental factors occurring during operation, and as a result, data such as overlay values ​​and TIS values ​​measured by the pattern are not constant and change.

[0006] In order to correct these optical errors, compensation is applied during wafer overlay measurement, but even when the compensation value is applied to the wafer, the problem arises that the data for each of the numerous targets formed on the wafer is not constant and changes.

[0007] The present invention is intended to solve various problems including the above-described problems, and discloses a method for calculating a correction value for correcting an error that occurs in an overlay measurement device, so that each target formed on a wafer can be individually corrected, thereby reducing the error of the overlay measurement device and improving the measurement accuracy, thereby providing a correction method for an overlay measurement device and a correction system for an overlay measurement device. However, these tasks are exemplary and the scope of the present invention is not limited thereby.

[0008] According to one embodiment of the present invention, a method for calibrating an overlay measuring device is provided. The method for calibrating the overlay measuring device comprises the steps of: (a) generating first data representing changes in TIS values ​​representing errors of the overlay measuring device generated by moving pinholes by a predetermined interval among a plurality of targets, and calculating a pinhole value at a position with the smallest dispersion in the first data as a first correction position of the pinhole; (b) generating second data representing changes in TIS values ​​generated by moving the pinholes by the predetermined interval from the first correction position among the plurality of targets, and calculating a pinhole value at a position with the smallest dispersion in the second data as a second correction position of the pinhole; (c) calculating an average value of the TIS values ​​at the second correction position calculated from the second data, and calculating pinhole positions at which TIS values ​​of the plurality of targets, when the average value is present, are located as correction values ​​of each of the plurality of targets; and (d) a step of storing the above correction values ​​in an automatic measurement program.

[0009] According to one embodiment of the present invention, the step (a) may include: (a-1) a step of measuring TIS values ​​for the plurality of targets preset at a reference position by the pinhole; (a-2) a step of re-measuring TIS values ​​for the plurality of targets at a first position where the pinhole has moved a predetermined distance from the reference position; (a-3) a step of calculating first data representing a change in TIS values ​​for the plurality of targets at the reference position and the first position; and (a-4) a step of calculating a pinhole value at a position where the dispersion of TIS values ​​is the smallest in a first graph representing the first data as the first correction position of the pinhole.

[0010] According to one embodiment of the present invention, the step (b) may include: (b-1) a step of measuring TIS values ​​for the plurality of targets at the first correction position by the pinhole; (b-2) a step of re-measuring TIS values ​​for the plurality of targets at a second position to which the pinhole has moved a predetermined distance from the first correction position; (b-3) a step of calculating second data representing changes in TIS values ​​for the plurality of targets at the first correction position and the second position; and (b-4) a step of calculating a pinhole value at a position where the dispersion of TIS values ​​is the smallest in the second graph representing the second data as the second correction position of the pinhole.

[0011] According to one embodiment of the present invention, (e) a step of performing overlay measurement of the plurality of targets by applying the correction values ​​stored in the automatic measurement program to the plurality of corresponding targets, respectively.

[0012] According to one embodiment of the present invention, a correction system for an overlay measurement device is provided. The correction system for the overlay measurement device comprises: a first optimization calculation unit that calculates first data representing changes in TIS values ​​representing errors of the overlay measurement device generated by moving pinholes by a predetermined interval among a plurality of targets, and calculates a pinhole value at a position with the smallest dispersion in the first data as a first correction position of the pinhole; a second optimization calculation unit that calculates second data representing changes in TIS values ​​generated by moving the pinholes by the predetermined interval from the first correction position among the plurality of targets, and calculates a pinhole value at a position with the smallest dispersion in the second data as a second correction position of the pinhole; a correction value calculation unit that calculates an average value of TIS values ​​at the second correction position calculated from the second data, and calculates pinhole positions at which TIS values, when the average value is present, among the TIS values ​​of the plurality of targets, are located, as correction values ​​of each of the plurality of targets; and a storage unit for storing the above correction values ​​in an automatic measurement program.

[0013] According to one embodiment of the present invention, the first optimization calculation unit may include a first measurement unit that controls the pinhole to measure TIS values ​​for the plurality of targets set in advance at a reference position and a first position moved by the predetermined interval from the reference position; a first data calculation unit that calculates the first data representing a change in TIS values ​​for the plurality of targets at the reference position and the first position; and a first correction position calculation unit that calculates a pinhole value at a position where the dispersion of TIS values ​​is the smallest in a first graph representing the first data as the first correction position of the pinhole.

[0014] According to one embodiment of the present invention, the second optimization calculation unit may include a second measurement unit that measures TIS values ​​for the plurality of targets at the first correction position and a second position where the pinhole is moved by the predetermined interval from the first correction position; a second data calculation unit that calculates the second data representing changes in TIS values ​​for the plurality of targets at the first correction position and the second position; and a second correction position calculation unit that calculates a pinhole value at a position where the dispersion of TIS values ​​is the smallest in the second graph representing the second data as the second correction position of the pinhole.

[0015] According to one embodiment of the present invention, the present invention may include an overlay measurement unit that performs overlay measurement of the plurality of targets by applying the correction values ​​stored in the automatic measurement program to the plurality of corresponding targets, respectively.

[0016] According to some embodiments of the present invention, in order to compensate for errors occurring in an overlay measurement device, a correction value can be calculated for each target formed on a wafer to compensate for the optical errors of the overlay measurement device, and each target can be individually compensated. Accordingly, the error of the overlay measurement device can be reduced and the measurement accuracy can be improved. Of course, the scope of the present invention is not limited by these effects.

[0017] FIG. 1 is a schematic diagram illustrating an overlay measuring device according to one embodiment of the present invention.

[0018] FIG. 2 is a top view showing a plurality of targets of a wafer mounted on a stage of the overlay measurement device of FIG. 1.

[0019] FIGS. 3 to 6 are drawings showing a calibration method of an overlay measuring device according to one embodiment of the present invention.

[0020] FIGS. 7 to 11 are graphs sequentially showing a TIS calculation method through a first graph calculated through first data in a correction method of an overlay measuring device according to one embodiment of the present invention.

[0021] FIGS. 12 to 15 are graphs sequentially showing a TIS calculation method through a second graph calculated through second data in a correction method of an overlay measuring device according to one embodiment of the present invention.

[0022] Figures 16 and 17 are graphs showing the calculation of the average value and correction value in the correction method of the overlay measuring device by enlarging area A of Figure 15.

[0023] FIGS. 18 and 19 are drawings showing a correction system of an overlay measuring device according to one embodiment of the present invention.

[0024] Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0025] The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art. The following embodiments may be modified in various ways, and the scope of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to more faithfully and completely explain the present disclosure and to fully convey the spirit of the present invention to those skilled in the art. In addition, the thickness and size of each layer in the drawings are exaggerated for convenience and clarity of explanation.

[0026] Hereinafter, embodiments of the present invention will be described with reference to drawings schematically illustrating ideal embodiments of the present invention. In the drawings, variations in the shapes depicted may be expected, for example, depending on manufacturing techniques and / or tolerances. Therefore, embodiments of the present invention should not be construed as limited to the specific shapes of the regions depicted herein, but should include, for example, variations in shapes resulting from manufacturing processes.

[0027] FIG. 1 is a schematic drawing of an overlay measurement device (1000) according to one embodiment of the present invention, and FIG. 2 is a top view showing a plurality of targets of a wafer mounted on a stage (500) of the overlay measurement device (1000) of FIG. 1.

[0028] As illustrated in FIGS. 1 and 2, the overlay measurement device (1000) is a device that detects a plurality of targets (T) formed on a wafer (W) and measures alignment errors for two layers. At this time, the plurality of targets (T) may include a first overlay key and a second overlay key formed on different layers, respectively.

[0029] For example, the first overlay key may be an overlay mark formed on a previous layer, and the second overlay key may be an overlay mark formed on a current layer. The overlay mark is formed on a scribe line at the same time as forming a layer for forming a semiconductor device in the die area. For example, the first overlay key may be formed together with an insulating film pattern, and the second overlay key may be formed together with a photoresist pattern formed on the insulating film pattern. In this case, the second overlay key is exposed to the outside, but the first overlay key is covered by the photoresist layer, and may be formed of an oxide having different optical properties from the second overlay key made of a photoresist material.

[0030] Additionally, although the physical locations of the first overlay key and the second overlay key are different, their focal planes may be the same or different.

[0031] As illustrated in FIG. 1, the overlay measuring device (1000) may include a light source unit (100), a lens unit (200), a detection unit (300), and a control unit (400).

[0032] The light source unit (100) can direct illumination to a plurality of targets (T) formed on a wafer (W). Specifically, the light source unit (100) can be configured to direct illumination to a plurality of targets (T) in which a first overlay key formed on a first layer laminated on the wafer (W) and a second overlay key formed on a second layer laminated above the first layer are located.

[0033] The light source unit (100) may include a light source (110), a spectrum filter (120), a polarizing filter, an aperture (130), and a beam splitter (140).

[0034] The light source (110) may be formed of a halogen lamp, a xenon lamp, a supercontinuum laser, a light-emitting diode, a laser induced lamp, etc., and may include various wavelengths such as ultraviolet (UV), visible light, or infrared (IR), but is not limited thereto.

[0035] The spectral filter (120) can adjust the center wavelength and bandwidth of the beam irradiated from the light source (110) to be suitable for image acquisition of the first overlay key and the second overlay key formed on the plurality of targets (T). For example, the spectral filter (120) can be formed of at least one or more of a filter wheel, a linear translation device, a flipper device, and a combination thereof.

[0036] The aperture (130) can be formed as an opaque plate with an opening through which light passes, and the beam irradiated from the light source (110) can be changed into a shape suitable for photographing a plurality of targets (T).

[0037] The aperture (130) may include at least one of an aperture stop that controls the amount of light and a field stop that controls the range of the image formed, and may be formed between the light source (110) and the beam splitter (140), as shown in FIG. 1, and although not shown, may be formed between the beam splitter (140) and the lens unit (200).

[0038] The beam splitter (140) separates the beam from the light source (110) into two beams by transmitting part of the beam that has passed through the aperture (130) from the light source (110) and reflecting part of the beam.

[0039] As illustrated in FIG. 1, the lens unit (200) may be formed with an objective lens (210) that focuses the light onto a measurement position of one of a plurality of targets (T), a lens focus actuator (220) that adjusts the distance between the objective lens (210) and the plurality of targets (T) at the measurement position, and a pinhole (230) that passes light reflected at the measurement position.

[0040] The objective lens (210) can focus the beam reflected from the beam splitter (140) onto the measurement position where the first overlay key and the second overlay key of the wafer (W) are formed and collect the reflected beam.

[0041] The objective lens (210) can be installed on a lens focus actuator (220).

[0042] The lens focus actuator (220) can adjust the distance between the objective lens (200) and the wafer (W) so that the focal plane is positioned at a plurality of targets (T).

[0043] The lens focus actuator (220) can adjust the focal length by vertically moving the objective lens (200) in the direction of the wafer (W) under the control of the control unit (400).

[0044] A pinhole (230) is formed by an opaque layer having a hole on top of a transparent substrate such as a glass substrate, so that light incident on the hole can pass through it. At this time, the hole is formed in multiple pieces, and can be used selectively depending on the size or shape of the hole.

[0045] The pinhole (230) can move in all directions based on the wafer (W), and for example, can control the position through which light passes by moving in the X-axis and Y-axis. At this time, by arbitrarily moving the position of the pinhole (230) to measure the TIS (Tool Induced Shift), an overlay correction value according to an error occurring in the overlay measurement device (1000) is calculated, and the position of the pinhole (230) can be corrected with the calculated correction value to measure the overlay.

[0046] When measuring a wafer (W) using a lens unit (200), the area where the image is captured changes as the objective lens (210) is controlled. At this time, the area where the wafer (W) can be captured by the objective lens (210) is the field of view. That is, the field of view (FOV) can be adjusted by the objective lens (210), and the focus can be adjusted by the lens focus actuator (220).

[0047] As illustrated in Fig. 1, the detection unit (300) can obtain a focus image at the measurement position through a beam reflected at the measurement position.

[0048] The detection unit (300) can capture the beam reflected from multiple targets (T) and passing through the beam splitter (140) to obtain images of the first overlay key and the second overlay key.

[0049] The detection unit (300) may include an optical detector capable of measuring a beam reflected from a plurality of targets (T), and for example, the optical detector may include a charge-coupled device (CCD) that converts light into charges to extract an image, a complementary metal-oxide-semiconductor (CMOS) sensor that is one of the integrated circuits, a photomultiplier tube (PMT) that measures light, an avalanche photodiode (APD) array as a photodetector, or various sensors that generate or capture images.

[0050] The detection unit (300) may include a filter, a polarizing plate, a beam block, and may further include any collection optical component (not shown) for collecting the illumination collected by the objective lens (210).

[0051] Additionally, the detection unit (300) can measure a global mark to confirm the correct position of the wafer (W).

[0052] A wafer (W) is placed on the upper part of a stage (500), the wafer (W) is fixed on the upper part of the stage (500), and the stage (500) can move and rotate horizontally so that a plurality of targets (T) of the wafer (W) can be measured by the lens unit (200) above.

[0053] The control unit (400) can control the direction of the light irradiated from the light source unit (100), control the lens unit (200) to focus the light on a plurality of targets (T) and collect the reflected beams, control the operation of the lens focus actuator (220) to focus the light on a plurality of targets (T) and obtain a focus image, control the detection unit (300) to obtain a focus image measured through the reflected beams collected from the lens unit (200), and control the movement of the stage (500) so that the overlay target is positioned below the lens unit (200).

[0054] In addition, although not shown, a series of processes performed in the control unit (400) may include a display unit (not shown) for the user to monitor, and may include an input unit (not shown) for the user to directly control.

[0055] That is, through the display unit, the user can check the data, images, graphs, etc. measured by the lens unit (200) and the detection unit (300) and produced through the same, and through the input unit, the user can directly control the light source unit (100), the lens unit (200), the detection unit (300), and the stage (500), or directly select, change, and produce images, correction values, etc. of multiple targets (T).

[0056] In addition, the overlay measuring device (1000) may include a memory that stores commands, programs, logic, etc. that control the operation of each component of the overlay measuring device by the control unit (400), and components may be added, changed, or deleted as needed.

[0057] FIGS. 3 to 6 are drawings showing a calibration method of an overlay measuring device according to one embodiment of the present invention, FIGS. 7 to 11 are graphs showing a TIS calculation method sequentially through a first graph calculated through first data in the calibration method of the overlay measuring device, FIGS. 12 to 15 are graphs showing a TIS calculation method sequentially through a second graph calculated through second data in the calibration method of the overlay measuring device, and FIGS. 16 and 17 are graphs showing calculation of an average value and a correction value in the calibration method of the overlay measuring device by enlarging area A of FIG. 15.

[0058] According to one embodiment of the present invention, a calibration method of an overlay measuring device may include, as illustrated in FIG. 3, (a) a step of calculating a first correction position (c1), (b) a step of calculating a second correction position (c2), (c) a step of calculating correction values ​​of a plurality of targets (T), and (d) a step of storing.

[0059] The above step (a) is a step of producing first data representing changes in TIS values ​​indicating errors of an overlay measuring device (1000) that occur by moving a pinhole (230) at a predetermined interval (D) in a plurality of targets (T), and producing a pinhole value at a position with the smallest dispersion in the first data as a first correction position (c1) of the pinhole (230).

[0060] Specifically, as illustrated in FIG. 4, the step (a) may include: (a-1) a step of measuring TIS values ​​at a reference position (s1), (a-2) a step of measuring TIS values ​​at a first position (p1), (a-3) a step of calculating first data, and (a-4) a step of calculating a first correction position (c1).

[0061] The above step (a-1) is a step in which the pinhole (230) measures TIS values ​​for a plurality of targets (T) preset at the reference position (s1).

[0062] The above step (a-1) is a step in which the pinhole (230) performs data collection measurement at a preset reference position (s1). For example, when the coordinates (x, y) of the reference position (s1) of the pinhole (230) are (30, 30), TIS values ​​for multiple targets (T) can be measured.

[0063] As an example, the reference position (s1) is an example of coordinates (x, y) where the X-axis and Y-axis are each 30, but in addition to the coordinates, the reference position can be expressed as a movement position expressed as a vertical or horizontal distance.

[0064] At this time, the plurality of targets (T) may include three or more arbitrary targets formed on the wafer (W), as shown in Fig. 2, and may include all targets formed on the wafer (W). In addition, the plurality of targets (T) may include targets at positions pre-stored in the automatic measurement program (ARO, Auto Recipe Optimization).

[0065] For example, as illustrated in FIG. 7, in step (a-1), when the position of the pinhole (230) is the reference position (s1), the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) can be measured. At this time, the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) may be measured with some of the same or different TIS values.

[0066] TIS is a value representing the error of the overlay measurement device (1000), and represents the difference between a measurement value measured at a reference angle of the wafer (W) in the overlay measurement device (1000) and a measurement value measured at an angle rotated 180 degrees from the reference angle. The higher the TIS value, the lower the optical alignment, which lowers the reliability of the measurement value. The lower the TIS value, the higher the optical alignment, which can increase the reliability of the measurement value.

[0067] The above step (a-2) is a step of re-measuring TIS values ​​for multiple targets (T) at a first position (p1) where the pinhole (230) has moved a predetermined distance (D) from the reference position (s1).

[0068] The above step (a-2) is a step for performing data collection measurement by offsetting the pinhole (230) by a preset predetermined interval (D). For example, in the above step (a-1), the TIS values ​​for multiple targets (T) are measured at the coordinates (x, y) of the pinhole (230) at (30, 30), and by moving 3 um, which is a predetermined interval (D), along each axis, the TIS values ​​for multiple targets (T) can be measured at the coordinates (x, y) at (33, 33).

[0069] For example, as illustrated in FIG. 8, in the step (a-2), the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) can be re-measured at the first position (p1) where the position of the pinhole (230) has moved a predetermined distance (D) from the reference position (s1). At this time, the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) measured at the first position (p1) may be partially the same or may be measured as different TIS values, and in particular, may be measured as different TIS values ​​from the respective TIS values ​​measured at the reference position (s1).

[0070] The above step (a-3) is a step of producing the first data representing changes in TIS values ​​for a plurality of targets (T) at a reference position (s1) and a first position (p1).

[0071] The above step (a-3) can produce the first data including TIS values ​​according to the change in position of the pinhole (230) of a plurality of targets (T) through the data of TIS values ​​collected in the above steps (a-1) and (a-2).

[0072] At this time, the first data may be represented by a first graph, and the first graph may be a first TIS graph for a plurality of targets (T). That is, the first TIS graph may include a graph that derives a change in the TIS values ​​of the plurality of targets (T) when the position of the pinhole (230) changes from the reference position (s1) to the first position (p1).

[0073] For example, as illustrated in FIG. 9, in the step (a-3), the position of the pinhole (230) can be graphed to show changes according to changes in the positions of the pinholes (230) of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) by connecting the TIS values ​​of the plurality of targets (T) at the reference position (s1) and the TIS values ​​of the plurality of targets (T) at the first position (p1).

[0074] The above step (a-4) can calculate the position of the pinhole with the smallest TIS 3 Sigma value for the plurality of targets (T) in the first data. At this time, the TIS 3 Sigma represents an error occurring in the overlay measurement device, i.e., the standard deviation of the TIS values ​​measured from the plurality of targets (T).

[0075] The above step (a-4) is a step of calculating the pinhole value at the position where the dispersion of TIS values ​​in the first graph representing the first data is the smallest as the first correction position (c1) of the pinhole (230).

[0076] For example, as illustrated in FIG. 10, the step (a-4) is a step of finding the position of the pinhole with the smallest dispersion in the first graph representing changes in the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) and storing it as the first correction position (c1). For example, the coordinates (x, y) of the first correction position (c1) calculated in the step (a-3) may be (31, 31).

[0077] The first correction position (c1) can be formed between the reference position (s1) and the first position (p1), as shown in FIG. 10, and can be formed at a value greater than the first position (p1) at a position outside the measured first position (p1), as shown in FIG. 11, and although not shown, the measured reference position (s1) can be formed at a value less than the reference position (s1) at a previous position.

[0078] The above step (b) is a step of calculating secondary data representing changes in TIS values ​​generated by moving a pinhole (230) from a primary correction position (c1) in a plurality of targets (T) by a predetermined interval (D), and calculating the pinhole value at a position with the least dispersion in the secondary data as the secondary correction position (c2) of the pinhole (230).

[0079] The above step (b) can calculate a second correction position (c2) that is a more accurate correction value than the first correction position (c1) calculated in the above step (a) by performing the above step (a) once more. However, the position of the pinhole (230) for measuring the TIS values ​​of multiple targets (t) can be performed subsequent to the first correction position (c1) calculated in the above step (a).

[0080] As illustrated in FIG. 5, the step (b) may include: (b-1) a step of measuring TIS values ​​at a first correction position (c1), (b-2) a step of measuring TIS values ​​at a second position (p2), (b-3) a step of calculating second data, and (b-4) a step of calculating a second correction position (c2).

[0081] The above step (b-1) is a step in which the pinhole (230) measures TIS values ​​for multiple targets (T) at the first correction position (c1).

[0082] The above step (b-1) is a step in which the pinhole (230) performs data collection measurement at the first correction position (c1) calculated in the above step (a). For example, when the coordinates (x, y) of the first correction position (c1) of the pinhole (230) are (31, 31), TIS values ​​for multiple targets (T) can be measured.

[0083] For example, as illustrated in FIG. 12, in the step (b-1), when the position of the pinhole (230) is the first correction position (c1), the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) can be measured. At this time, the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) may include TIS values ​​re-measured at the first correction position (c1), or any one of the TIS values ​​at the first correction position (c1) calculated in the step (a).

[0084] The above step (b-2) is a step of re-measuring TIS values ​​for multiple targets (T) at a second position (p2) where the pinhole (230) has moved a predetermined distance (D) from the first correction position (c1).

[0085] The above step (b-2) is a step for performing data collection measurement by offsetting the pinhole (230) by a predetermined interval (D) set in the above step (a). For example, in the above step (b-1), the pinhole (230) measures TIS values ​​for multiple targets (T) at coordinates (x, y) (31, 31), and moves by a predetermined interval (D) of 3 um in each axis to measure TIS values ​​for multiple targets (T) at coordinates (x, y) (34, 34).

[0086] For example, as illustrated in FIG. 13, in the step (b-2), the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) can be re-measured at a second position (p2) where the position of the pinhole (230) has moved a predetermined distance (D) from the first correction position (c1). At this time, the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) measured at the second position (p2) may be partially the same or may be measured as different TIS values, and in particular, may be measured as different TIS values ​​from the respective TIS values ​​measured at the first correction position (c1).

[0087] The above step (b-3) is a step of producing the second data indicating changes in TIS values ​​for a plurality of targets (T) at the first correction position (c1) and the second position (p2).

[0088] The above step (b-3) can produce the second data including TIS values ​​according to the change in position of the pinhole (230) of a plurality of targets (T) through the data of TIS values ​​collected in the above steps (b-1) and (b-2).

[0089] At this time, the second data may be represented by a second graph, and the second graph may be a second TIS graph for a plurality of targets (T) different from the first graph. That is, the second TIS graph may include a graph that derives a change in the TIS values ​​of the plurality of targets (T) when the position of the pinhole (230) changes from the first correction position (c1) to the second position (p2).

[0090] For example, as illustrated in FIG. 14, in the step (b-3), the position of the pinhole (230) can be graphed again to show the change in position of the pinhole (230) of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) by connecting the TIS values ​​of the plurality of targets (T) at the first correction position (c1) and the TIS values ​​of the plurality of targets (T) at the second position (p2).

[0091] The above step (b-4) can calculate the position of the pinhole with the smallest TIS 3 Sigma value for multiple targets (T) in the second data.

[0092] Specifically, the step (b-4) above is a step of calculating the pinhole value at the position where the dispersion of TIS values ​​in the second graph representing the second data is the smallest as the secondary correction position (c2) of the pinhole (230).

[0093] For example, as illustrated in FIG. 15, the step (b-4) is a step of finding the position of the pinhole with the smallest dispersion in the second graph representing changes in the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) and storing it as the secondary correction position (c2). For example, the coordinates (x, y) of the secondary correction position (c2) calculated in the step (b-3) may be (31.5, 31.5).

[0094] The secondary correction position (c2) can be formed between the primary correction position (c1) and the second position (p2), as shown in Fig. 15. At this time, the primary correction position (c1), which is the position of the pinhole with the smallest TIS 3 Sigma value for the plurality of targets (T) in the first data of step (a), is calculated, and accordingly, the secondary correction position (c2) can be calculated closer to the primary correction position (c1) than the second position (p2).

[0095] The above step (c) is a step of calculating the average value (Avg) of the TIS values ​​at the secondary correction position (c2) calculated from the secondary data, and calculating the pinhole positions where the TIS values ​​are located when the average value (Avg) is among the TIS values ​​of the plurality of targets (T), as correction values ​​of each of the plurality of targets (T).

[0096] The above step (c) can calculate the average value (Avg) of the TIS values ​​at the secondary correction position (c2) calculated in the above step (b).

[0097] For example, as illustrated in FIG. 16, in the step (c), the TIS values ​​of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) at the second correction position (c2) are calculated as the first TIS value (Ovl.t1), the second TIS value (Ovl.t2), the third TIS value (Ovl.t3), the fourth TIS value (Ovl.t4), and the fifth TIS value (Ovl.t5), and the average of the TIS values ​​is calculated to calculate the average value (Avg).

[0098] The above step (c) can calculate the correction positions of the pinholes (230) of the first target (t1), the second target (t2), the third target (t3), the fourth target (t4), and the fifth target (t5) at the average value (Avg) of the TIS value.

[0099] For example, as illustrated in FIG. 17, in the step (c), the first correction value (C.t1), the second correction value (C.t2), the third correction value (C.t3), the fourth correction value (C.t4), and the fifth correction value (C.t5) where the TIS values ​​in the case of the average value (Avg) are located can be calculated, respectively. More specifically, for example, the first correction value (C.t1) can be 31.7, the second correction value (C.t2) can be 31.6, the third correction value (C.t3) can be 31.1, the fourth correction value (C.t4) can be 31.8, and the fifth correction value (C.t5) can be 31.3.

[0100] That is, the correction value of the pinhole (230) for a plurality of targets (T) formed on the wafer (W) can be individually calculated.

[0101] The above step (d) is a step of storing the correction values ​​in the automatic measurement program.

[0102] For example, the step (d) is a step of storing the first correction value (C.t1), the second correction value (C.t2), the third correction value (C.t3), the fourth correction value (C.t4), the fifth correction value (C.t5), and the nth correction value (C.tn) calculated in the step (c) as correction values ​​of each of the plurality of targets (T) in the automatic measurement program.

[0103] The above automatic measurement program can automatically optimize the measurement options of the overlay measurement recipe. The optimization options may include filters, aperture numerical aperture (NA), focus, pinhole, etc.

[0104] In addition, the automatic measurement program may include, in addition to the optimized recipe information regarding the operation of the measurement device, information about the measurement device and information about the wafer (W) introduced into the overlay measurement device (1000). Accordingly, the automatic measurement program may automatically derive optimal options through the optimized recipe information, the measurement device information, and the measurement target position information.

[0105] According to one embodiment of the present invention, a method for calibrating an overlay measurement device may include a step of performing (e) overlay measurement, as illustrated in FIG. 6.

[0106] The above step (e) is a step for performing overlay measurement of a plurality of targets (T) formed on a wafer (W). At this time, correction values ​​corresponding to each of the plurality of targets (T) stored in the automatic measurement program are applied, and the pinhole (230) can be moved with the correction value corresponding to each target to measure the overlay value.

[0107] For example, when measuring a first target (t1) of a wafer (W), the pinhole (230) can be moved with a first correction value (C.t1) to measure the overlay value of the first target (t1), when measuring a second target (t2), the pinhole (230) can be moved with a second correction value (C.t2) to measure the overlay value of the second target (t2), and when measuring an n-th target (tn), the pinhole (230) can be moved with an n-th correction value (C.tn) to measure the overlay value of the n-th target (tn).

[0108] That is, when performing overlay measurement on a plurality of targets (T) formed on a wafer (W), the accuracy of overlay measurement on the plurality of targets (T) can be improved by individually applying a correction value to each of the plurality of targets (T).

[0109] FIGS. 18 and 19 are drawings showing a correction system of an overlay measuring device according to one embodiment of the present invention.

[0110] A correction system of an overlay measuring device according to one embodiment of the present invention may include a first optimization calculation unit (10), a second optimization calculation unit (20), a correction value calculation unit (30), and a storage unit (40).

[0111] The first optimization output unit (10) outputs first data representing changes in TIS values ​​generated by moving pinholes (230) at predetermined intervals in a plurality of targets (T), and can output the pinhole value at the position with the smallest dispersion in the first data as the first correction position (c1) of the pinhole (230).

[0112] Specifically, as illustrated in FIG. 18, the first optimization output unit (10) may include a first measurement unit (11), a first data output unit (12), and a first correction position output unit (13).

[0113] The first measuring unit (11) can measure TIS values ​​for a plurality of preset targets (T) at a first position (p1) moved by a predetermined interval (D) from the reference position and the reference position (s1) of the pinhole (230).

[0114] The first measuring unit (11) can perform data collection measurement at a preset reference position (s1) of the pinhole (230). For example, when the pinhole (230) is 30 um from the reference position (s1), TIS values ​​for multiple targets (T) can be measured.

[0115] For example, as illustrated in Fig. 19, the first measuring unit (11) can measure TIS values ​​of the first target, the second target, and the nth target when the position of the pinhole (230) is the reference position (s1). At this time, the first target, the second target, and the nth target may be measured with some identical or different TIS values.

[0116] The first data generating unit (12) can generate the first data indicating changes in TIS values ​​for a plurality of targets (T) at the reference position (s1) and the first position (p1).

[0117] The first data generation unit (12) can perform data collection measurement by offsetting the pinhole (230) by a preset interval (D). For example, in the first measurement unit (11), the pinhole (230) can measure TIS values ​​for multiple targets (T) at 30 um, and then move by 3 um, which is a preset interval (D), to measure TIS values ​​for multiple targets (T) at 33 um.

[0118] For example, the first data generating unit (12) can re-measure the TIS values ​​of the first target, the second target, and the n-th target at the first position (p1) where the position of the pinhole (230) has moved a predetermined distance (D) from the reference position (s1). At this time, the TIS values ​​of the first target, the second target, and the n-th target measured at the first position (p1) may be partially the same or may be measured as different TIS values, and in particular, may be measured as different TIS values ​​from the respective TIS values ​​measured at the reference position (s1).

[0119] The first correction position calculation unit (13) can calculate the pinhole value at the position where the dispersion of TIS values ​​is the smallest in the first graph representing the first data as the first correction position (c1) of the pinhole (230).

[0120] The first correction position calculation unit (13) can calculate the first data including TIS values ​​according to the change in position of the pinhole (230) of a plurality of targets (T) through the data of TIS values ​​collected from the first measurement unit (11) and the first data calculation unit (12).

[0121] At this time, the first data may be represented by a first graph, and the first graph may include a graph that derives a change in the TIS values ​​of a plurality of targets (T) when the position of the pinhole (230) changes from the reference position (s1) to the first position (p1).

[0122] For example, the first correction position calculation unit (13) can graph the change in position of the pinhole (230) of the first target, the second target, and the nth target by connecting the TIS values ​​of the plurality of targets (T) at the reference position (s1) and the TIS values ​​of the plurality of targets (T) at the first position (p1).

[0123] The first correction position calculation unit (13) can calculate the position of the pinhole with the smallest TIS 3 Sigma value for a plurality of targets (T) in the first data.

[0124] For example, the first correction position calculation unit (13) can find the position of the pinhole with the smallest dispersion in the first graph representing the change in TIS values ​​of the first target, the second target, and the nth target, and store it as the first correction position (c1). More specifically, for example, the first correction position (c1) can be 31 um.

[0125] At this time, the first correction position (c1) may be formed between the reference position (s1) and the first position (p1), or may be formed at a value greater than the first position (p1) at a position outside the measured first position (p1), or may be formed at a value less than the reference position (s1) at a previous position of the measured reference position (s1).

[0126] The second optimization output unit (20), as illustrated in FIG. 19, outputs second data representing changes in TIS values ​​generated by moving a pinhole (230) from a first correction position (c1) at a predetermined interval (D) in a plurality of targets (T), and can output the pinhole value at a position with the least dispersion in the second data as the second correction position (c2) of the pinhole (230).

[0127] The second optimization calculation unit (20) can perform the same operation as the first optimization calculation unit (10) once more to calculate a second correction position (c2) that is a more accurate correction value than the first correction position (c1) calculated by the first optimization calculation unit (10). However, the position of the pinhole (230) that measures the TIS values ​​of multiple targets (t) can be performed subsequent to the first correction position (c1) calculated by the first optimization calculation unit (10).

[0128] As illustrated in Fig. 18, the second optimization output unit (20) may include a second measurement unit (21), a second data output unit (22), and a second correction position output unit (23).

[0129] The second measuring unit (21) can measure TIS values ​​for a plurality of targets (T) at the first correction position (c1) and the second position (p2) moved by a predetermined interval (D) from the first correction position (c1) of the pinhole (230).

[0130] The second measurement unit (21) can perform data collection measurement at the first correction position (c1) calculated by the first optimization calculation unit (10) of the pinhole (230). For example, when the first correction position (c1) of the pinhole (230) is 31 um, TIS values ​​for multiple targets (T) can be measured.

[0131] For example, the second measuring unit (21) can measure the TIS values ​​of the first target, the second target, and the n-th target when the position of the pinhole (230) is the first correction position (c1). At this time, the TIS values ​​of the first target, the second target, and the n-th target may include any one of the TIS values ​​measured again at the first correction position (c1) or the TIS values ​​at the first correction position (c1) calculated by the first optimization calculation unit (10).

[0132] The second data generating unit (22) can generate the second data indicating changes in TIS values ​​for a plurality of targets (T) at the first correction position (c1) and the second position (p2).

[0133] The second data generating unit (22) can perform data collection measurement by offsetting the pinhole (230) by a predetermined interval (D) set in the first optimization generating unit (10). For example, the second data generating unit (22) can measure TIS values ​​for multiple targets (T) at 31 um, and move the pinhole (230) along each axis by a predetermined interval (D) of 3 um to measure TIS values ​​for multiple targets (T) at 34 um.

[0134] For example, the second data generating unit (22) can re-measure the TIS values ​​of the first target, the second target, and the n-th target at a second position (p2) where the position of the pinhole (230) has moved a predetermined distance (D) from the first correction position (c1). At this time, the TIS values ​​of the first target, the second target, and the n-th target measured at the second position (p2) may be partially the same or may be measured as different TIS values, and in particular, may be measured as different TIS values ​​from the respective TIS values ​​measured at the first correction position (c1).

[0135] The second correction position calculation unit (23) can calculate the pinhole value at the position where the dispersion of TIS values ​​is the smallest in the second graph representing the second data as the second correction position (c2) of the pinhole (230).

[0136] The second correction position calculation unit (23) can calculate the second data including TIS values ​​according to the change in position of the pinhole (230) of a plurality of targets (T) through the data of TIS values ​​collected from the second measurement unit (21) and the second data calculation unit (22).

[0137] At this time, the second data may be represented by a second graph, and the second graph may be a graph for a plurality of targets (T) different from the first graph. That is, the second graph may include a graph that derives a change in the TIS values ​​of the plurality of targets (T) when the position of the pinhole (230) changes from the first correction position (c1) to the second position (p2).

[0138] For example, in the second correction position calculation unit (23), the position of the pinhole (230) can be graphed again by connecting the TIS values ​​of the plurality of targets (T) at the first correction position (c1) and the TIS values ​​of the plurality of targets (T) at the second position (p2), so that the change in position of the pinhole (230) of the first target, the second target, and the nth target can be represented again.

[0139] The second correction position calculation unit (23) can calculate the position of the pinhole with the smallest TIS 3 Sigma value for multiple targets (T) from the second data.

[0140] For example, the second correction position calculation unit (23) can find the position of the pinhole with the smallest dispersion in the second graph representing the change in the TIS values ​​of the first target, the second target, and the nth target and store it as the second correction position (c2). For example, the second correction position (c2) calculated by the second correction position calculation unit (23) can be 31.5 um.

[0141] The second correction position (c2) can be formed between the first correction position (c1) and the second position (p2). At this time, the first correction position (c1), which is the position of the pinhole with the smallest TIS 3 Sigma value for the plurality of targets (T) in the first data of the step (a), is calculated, and accordingly, the second correction position (c2) can be calculated closer to the first correction position (c1) than the second position (p2).

[0142] The correction value calculation unit (30) calculates the average value (Avg) of the TIS values ​​at the second correction position (c2) calculated from the second data, and can calculate the pinhole positions where the TIS values ​​are located when the average value (Avg) is among the TIS values ​​of the plurality of targets (T) as correction values ​​(C.t1, C.t2, C.t3, C.t4, C.t5) of each of the plurality of targets (T).

[0143] The correction value calculation unit (30) can calculate the average value of the TIS values ​​at the second correction position (c2) calculated in the second optimization calculation unit (20).

[0144] For example, the correction value calculation unit (30) can calculate the TIS values ​​of the first target, the second target, and the n-th target as the first TIS value, the second TIS value, and the n-th TIS value at the second correction position (c2), and calculate the average of the TIS values ​​to calculate the average value.

[0145] The correction value calculation unit (30) can calculate the correction position of the pinhole (230) of the first target, the second target, and the nth target from the TIS value of the average value.

[0146] For example, in the correction value calculation unit (30), when the TIS values ​​of the first target, the second target, and the nth target are the average values, the first correction value, the second correction value, and the nth correction value can be calculated, respectively.

[0147] That is, the correction value of the pinhole (230) for a plurality of targets (T) formed on the wafer (W) can be individually calculated.

[0148] The storage unit (40) can store the above correction values ​​in an automatic measurement program.

[0149] For example, the storage unit (40) can store the first correction value, the second correction value, and the nth correction value calculated by the correction value calculation unit (30) as correction values ​​of each of the plurality of targets (T) in the automatic measurement program.

[0150] According to one embodiment of the present invention, a calibration system of an overlay measuring device may include an overlay measuring unit (50), as illustrated in FIG. 18.

[0151] The overlay measurement unit (50) can perform overlay measurement of a plurality of targets (T) by applying the correction values ​​stored in the automatic measurement program to each corresponding plurality of targets (T).

[0152] For example, when measuring the first target of the wafer (W), the pinhole (230) can be moved with the first correction value to measure the overlay value of the first target, when measuring the second target, the pinhole (230) can be moved with the second correction value to measure the overlay value of the second target, and when measuring the nth target, the pinhole (230) can be moved with the nth correction value to measure the overlay value of the nth target.

[0153] According to the above, the overlay measurement device and the correction method of the overlay measurement device of the present invention can individually identify optical errors for each target, calculate optical errors for correcting them through the above-described sequence, and apply them during overlay measurement to correct optical errors for each target.

[0154] Accordingly, when performing overlay measurement on a plurality of targets (T) formed on a wafer (W), the accuracy of overlay measurement on the plurality of targets (T) can be improved by individually applying correction values ​​to each of the plurality of targets (T).

[0155] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent alternative embodiments are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

Claims

1. (a) A step of producing first data representing changes in TIS values ​​indicating errors of an overlay measuring device caused by moving pinholes at a predetermined interval in multiple targets, and producing a pinhole value at a position with the smallest dispersion in the first data as the first correction position of the pinhole; (b) a step of generating secondary data representing changes in TIS values ​​generated by moving the pinhole from the primary correction position by the predetermined interval in the plurality of targets, and calculating the pinhole value at the position with the least dispersion in the secondary data as the secondary correction position of the pinhole; (c) a step of calculating an average value of TIS values ​​at the second correction position derived from the second data, and calculating the pinhole positions where the TIS values ​​of the plurality of targets, which are the average values ​​among the TIS values ​​of the plurality of targets, are located as correction values ​​of each of the plurality of targets; and (d) a step of storing the above correction values ​​in an automatic measurement program; A method for calibrating an overlay measuring device, comprising:

2. In paragraph 1, Step (a) above, (a-1) a step of measuring TIS values ​​for the plurality of targets preset at the reference position by the pinhole; (a-2) a step of re-measuring TIS values ​​for the plurality of targets at a first position where the pinhole has moved a predetermined distance from the reference position; (a-3) a step of producing the first data representing changes in TIS values ​​for the plurality of targets at the reference position and the first position; and (a-4) A step of calculating the pinhole value at the position where the dispersion of TIS values ​​is the smallest in the first graph representing the first data as the first correction position of the pinhole; A method for calibrating an overlay measuring device, comprising:

3. In paragraph 1, Step (b) above, (b-1) a step of measuring TIS values ​​for the plurality of targets at the first correction position by the pinhole; (b-2) a step of re-measuring TIS values ​​for the plurality of targets at a second position where the pinhole has moved a predetermined distance from the first correction position; (b-3) a step of generating the second data representing the change in TIS values ​​for the plurality of targets at the first correction position and the second position; and (b-4) A step of calculating the pinhole value at the position where the dispersion of TIS values ​​is the smallest in the second graph representing the second data as the second correction position of the pinhole; A method for calibrating an overlay measuring device, comprising:

4. In paragraph 1, (e) a step of performing overlay measurement of the plurality of targets by applying the correction values ​​stored in the automatic measurement program to the plurality of corresponding targets respectively; A method for calibrating an overlay measuring device, comprising:

5. A first optimization calculation unit that calculates first data representing changes in TIS values ​​that indicate errors of an overlay measuring device caused by moving pinholes at a predetermined interval in multiple targets, and calculates the pinhole value at a position with the smallest dispersion in the first data as the first correction position of the pinhole; A second optimization calculation unit that calculates second data representing changes in TIS values ​​generated by moving the pinhole from the first correction position by the predetermined interval among the plurality of targets, and calculates the pinhole value at the position with the least dispersion in the second data as the second correction position of the pinhole; A correction value calculating unit that calculates an average value of TIS values ​​at the second correction position derived from the second data, and calculates the pinhole positions where the TIS values ​​of the plurality of targets, which are the average values ​​among the TIS values ​​of the plurality of targets, are located as correction values ​​of each of the plurality of targets; and A storage unit that stores the above correction values ​​in an automatic measurement program; A calibration system for an overlay measuring device, comprising:

6. In paragraph 5, The above first optimization output section is, A first measuring unit that controls the pinhole to measure TIS values ​​for the plurality of preset targets at a reference position and a first position moved by the predetermined interval from the reference position; A first data generating unit for generating the first data representing changes in TIS values ​​for the plurality of targets at the reference position and the first position; and A first correction position calculation unit that calculates a pinhole value at a position where the dispersion of TIS values ​​is the smallest in a first graph representing the first data as the first correction position of the pinhole; A calibration system for an overlay measuring device, comprising:

7. In paragraph 5, The second optimization output section is, A second measuring unit for measuring TIS values ​​for the plurality of targets at the first correction position and a second position moved by the predetermined interval from the first correction position; A second data generating unit for generating second data representing changes in TIS values ​​for the plurality of targets at the first correction position and the second position; and A second correction position calculation unit that calculates a pinhole value at a position where the dispersion of TIS values ​​is the smallest in the second graph representing the second data as the second correction position of the pinhole; A calibration system for an overlay measuring device, comprising:

8. In paragraph 5, An overlay measurement unit that performs overlay measurement of a plurality of targets by applying the correction values ​​stored in the automatic measurement program to the corresponding plurality of targets respectively; A calibration system for an overlay measuring device, comprising:

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