Method for optimizing an overlay measuring device and an overlay measuring device that performs this optimization.

Abstract

The present invention relates to a method for optimizing an overlay measurement device. More specifically, it relates to a method for optimizing an overlay measurement device by adjusting the position and shape of a plurality of apertures provided on the optical path of the overlay measurement device. The present invention provides a method for optimizing an overlay measurement device by adjusting at least one of the position and aperture shape of a plurality of apertures arranged on the optical path of the overlay measurement device, comprising: a) measuring an initial performance index for at least one position on a semiconductor wafer on which an overlay mark to be measured is formed, using an initial parameter combination based on the positions and aperture shapes of the plurality of apertures; b) automatically obtaining an optimal parameter combination based on the positions and aperture shapes of the plurality of apertures based on the initial performance index; and c) changing the position and aperture shape of the plurality of apertures according to the optimal parameter combination.

Description

Technical Field

[0001] The present invention relates to a method for optimizing an overlay measurement device, and more particularly, to a method for optimizing an overlay measurement device by adjusting the position and shape of a plurality of diaphragms provided on the optical path of the overlay measurement device.

Background Art

[0002] On a semiconductor substrate, a plurality of pattern layers are sequentially formed. Also, through double patterning or the like, a circuit of one layer may be formed by dividing it into two patterns. If these pattern layers or a plurality of patterns of one layer are accurately formed at a predetermined position, a desired semiconductor element can be manufactured.

[0003] Therefore, in order to confirm whether the pattern layers are accurately aligned, an overlay mark formed simultaneously with the pattern layers is used.

[0004] A method for measuring an overlay using an overlay mark is as follows. First, on a pattern layer formed in a previous process, for example, an etching process, one structure that is a part of the overlay mark is formed simultaneously with the formation of the pattern layer. Then, in a subsequent process, for example, a photolithography process, the remaining structures of the overlay mark are formed on the photoresist.

[0005] Also, through an overlay measurement device, an image of the overlay structure (image acquisition through the photoresist layer) of the pattern layer formed in the previous process and an image of the overlay structure of the photoresist layer are acquired, and the overlay measurement device measures the overlay error by measuring the offset value between the centers of these images.

[0006] More specifically, Japanese Patent Publication No. 2020-112807 discloses a method for determining relative shifts between different layers or different patterns by capturing an image of an overlay mark formed on a substrate, selecting a plurality of working zones from the captured image, forming an informational signal for each of the selected working zones, and comparing these signals.

[0007] Figure 1 is a plan view of an example of an overlay mark. The overlay mark 1 shown in Figure 1 comprises four working zone sets 4, 5, 6, and 7. Each working zone set 4, 5, 6, and 7 comprises two working zones arranged diagonally to each other. Each working zone set 4, 5, 6, and 7 is used to measure the overlay error in the X-axis or Y-axis direction of the pattern layer formed together with the working zone set. To prevent interference phenomena, structure 2 formed with the first pattern layer and structure 3 formed with the second pattern layer are arranged so as not to overlap each other.

[0008] Each working zone includes bars positioned at regular intervals from the center of overlay mark 1 to the outer edge of overlay mark 1. Therefore, using the overlay measurement device, periodic signals as shown in Figure 2 can be obtained from two working zones belonging to working zone sets 4, 5, 6, and 7, respectively. The graph in Figure 2 can be obtained, for example, from a portion of region 8 selected in Figure 1.

[0009] In the graph of Figure 2, the peaks are shown in the areas where the bars are placed. Since the conventional overlay mark 1 has periodically placed bars, the acquired signal also exhibits periodicity. The overlay is then measured through correlation analysis of two periodic signals acquired from two selected regions 8 and 8'.

[0010] Before performing the above measurements to determine the overlay error, optimization of the overlay measurement device is necessary. Specifically, optimization of performance indicators of the overlay measurement device, such as accuracy, total measurement uncertainty (TMU), tool-induced shift (TIS), and move, acquire, measure (MAM) time, is required.

[0011] The overall measurement uncertainty depends on several coefficients, including precision, the mean of the tool-guided shift, and the 3-sigma value of the tool-guided shift. A small overall measurement uncertainty value is preferable.

[0012] Tool-induced shift can be quantified by measuring the same feature on the semiconductor wafer, such as an overlay mark, at 0 and 180-degree rotations of the semiconductor wafer. In this case, the tool-induced shift is equal to half the sum of the overlay error measurements at 0 and 180-degree rotations. It is preferable that the average of the X and Y values ​​of the tool-induced shift measured at multiple locations is close to 0, and the 3-sigma value is small.

[0013] More specifically, tool-induced shift can be measured in the following way:

[0014] First, multiple overlay marks are captured at numerous sites on the semiconductor wafer at 0 and 180-degree rotations to acquire overlay mark images. These images are then analyzed to measure the overlay errors in the X and Y directions, respectively.

[0015] Additionally, half of the sum of the measured overlay errors for the same overlay mark rotated 0 and 180 degrees is obtained as the tool-guided shift value at that location. The tool-guided shift value is also obtained separately for each site, with X and Y directions.

[0016] Figure 3 shows the measurement sites on the semiconductor wafer as points, and Figure 4 shows the tool-guided shift values ​​obtained from the sites shown in Figure 3 on the X and Y planes.

[0017] As shown in Figure 4, tool-induced shift values ​​can vary from site to site. The average value of the tool-induced shift is (0,0), and it is preferable that the 3-sigma value of the tool-induced shift is as small as possible. For example, the specifications for the tool-induced shift may be set to an average value of less than 0.3 nm and a 3-sigma value of less than 0.4 nm.

[0018] Shorter travel, acquisition, and measurement times mean faster frame times.

[0019] Various operating parameters are adjusted by an operator until the overlay measuring device is optimized for a specific overlay mark. This optimization procedure is repeated for other overlay marks. Because this optimization procedure is performed by an operator, it is time-consuming. Furthermore, if multiple operators are optimizing the overlay measuring device, the performance of each device does not need to be consistent. [Prior art documents] [Patent Documents]

[0020] [Patent Document 1] Korean Registered Patent Publication No. 10-1329827 [Patent Document 2] Korean Published Patent No. 10-2022-0164003 [Overview of the project] [Problems that the invention aims to solve]

[0021] The present invention aims to improve upon the above-mentioned problems and provides a method for optimizing an overlay measuring device by adjusting at least one of the positions and aperture shapes of a plurality of apertures arranged on the optical path of the overlay measuring device.

Means for Solving the Problem

[0022] To achieve the above object, the present invention provides a method for optimizing an overlay measurement apparatus by adjusting at least one of the positions and aperture shapes of a plurality of diaphragms arranged on the optical path of the overlay measurement apparatus, the method comprising: a) measuring an initial performance index using an initial parameter combination based on the positions and aperture shapes of the plurality of diaphragms for at least one position on a semiconductor wafer on which an overlay mark to be measured is formed; b) automatically obtaining an optimal parameter combination based on the initial performance index, the optimal parameter combination being based on the positions and aperture shapes of the plurality of diaphragms; and c) changing the positions and aperture shapes of the plurality of diaphragms according to the optimal parameter combination.

[0023] Further, in step b), the optimal parameter combination is obtained by inputting the initial performance index into a machine learning model configured to output the optimal parameter combination, thereby providing a method for optimizing an overlay measurement apparatus.

[0024] Further, in step b), the step of automatically obtaining the optimal parameter combination includes: obtaining a performance index for each of a plurality of parameter combinations based on the positions and aperture shapes of the plurality of diaphragms for each parameter combination; assigning a weight to the performance index of each parameter combination; and selecting, as the optimal parameter combination, one parameter combination that minimizes the sum of the weighted performance indices among the plurality of parameter combinations, thereby providing a method for optimizing an overlay measurement apparatus.

[0025] Also provided is an optimization method for an overlay measurement apparatus, wherein the performance index includes at least one of accuracy, total measurement uncertainty (TMU), tool induced shift (TIS), move, acquire and measure (MAM) time, and respective statistical values thereof.

[0026] Also provided is an optimization method for an overlay measurement apparatus, wherein the diaphragm includes at least one field stop and at least one aperture stop.

[0027] Also provided is an optimization method for an overlay measurement apparatus, wherein the overlay measurement apparatus is an infinite corrected optical system, and at least one of the aperture stops is installed in an infinite corrected section where light travels parallel.

[0028] Also provided is an optimization method for an overlay measurement apparatus, wherein the overlay measurement apparatus includes an illumination source that generates light, an objective lens that receives light and directs the light toward a semiconductor wafer and collects the light reflected from the semiconductor wafer, and an image detector that detects an overlay mark formed on the semiconductor wafer from the collected light and generates an overlay mark image, and at least one of the aperture stops is disposed between the image detector and the objective lens of the overlay measurement apparatus.

[0029] Also provided is an optimization method for an overlay measurement apparatus, wherein the aperture shape of the diaphragm is selected from a circle, a square, a ring shape, and a cross shape.

[0030] Also provided is an optimization method for an overlay measurement apparatus, wherein at least one of the plurality of diaphragms is a variable diaphragm.

[0031] Furthermore, the present invention provides an optimization method for an overlay measuring device in which at least one of the variable apertures is an iris-type variable aperture whose aperture diameter is changed.

[0032] Furthermore, the present invention provides an optimization method for an overlay measuring device, wherein at least one of the variable apertures comprises a plate having a plurality of apertures of different shapes, and the apertures arranged on the optical path are changed by rotating or linearly moving the plate.

[0033] The present invention also provides an overlay measuring apparatus comprising: an imaging system including a plurality of apertures arranged on an optical path for acquiring an overlay mark image; and a controller communicatively coupled to the imaging system, wherein the controller includes at least one memory containing instruction words and a processor configured to execute the instruction words contained in the at least one memory, the processor executing the instruction words to perform a) a measurement of an initial performance index of the overlay measuring apparatus using an initial parameter combination based on the positions and aperture shapes of the plurality of apertures for at least one location on a semiconductor wafer on which an overlay mark to be measured is formed; b) an automatic acquisition of an optimal parameter combination based on the positions and aperture shapes of the plurality of apertures based on the initial performance index; and c) a step of changing the positions and aperture shapes of the plurality of apertures according to the optimal parameter combination. [Effects of the Invention]

[0034] The optimization method for an overlay measuring device according to the present invention automatically acquires the optimal combination of multiple aperture positions and aperture shapes based on measured initial performance indicators, thereby minimizing human intervention. This reduces the time required for optimization. Furthermore, it allows for consistent performance across different overlay measuring devices. [Brief explanation of the drawing]

[0035] [Figure 1] This is a plan view of an example of an overlay mark. [Figure 2] Figure 1 shows the signal acquired from one working zone of the overlay mark. [Figure 3] This diagram shows measurement sites on a semiconductor wafer as dots. [Figure 4] Figure 3 shows the tool-guided shift values ​​obtained from the site indicated, plotted on the X and Y planes. [Figure 5] This is a schematic diagram of an overlay measurement device according to one embodiment of the present invention. [Figure 6] This figure shows an example of a plate-type variable aperture. [Figure 7] This is a flowchart of an optimization method for an overlay measurement device according to one embodiment of the present invention. [Modes for carrying out the invention]

[0036] One embodiment of the present invention will be described in detail below with reference to the accompanying drawings. However, embodiments of the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments detailed below. Embodiments of the present invention are provided to give a more complete explanation of the present invention to those who are ordinary skill in the art. Therefore, the shapes of elements in the drawings are exaggerated to emphasize a clearer explanation, and elements indicated by the same reference numerals in the drawings mean the same element.

[0037] Figure 5 is a schematic diagram of an overlay measurement device according to one embodiment of the present invention.

[0038] The overlay measurement apparatus 10 includes an imaging system 100 configured to acquire an overlay mark image and a controller 200. The overlay measurement apparatus 10 photographs a semiconductor wafer on which overlay marks are formed to acquire an overlay mark image. The acquired overlay mark image is then analyzed to measure the overlay error between pattern layers formed on the wafer.

[0039] The controller 200 is wired or wirelessly connected to the imaging system 100. The controller 200 includes at least one processor, hardware such as at least one memory, and software installed in at least one memory. The controller 200 can use software instructions to instruct at least one processor to perform steps of the optimization method for the overlay measuring device 10.

[0040] As shown in Figure 5, the imaging system 100 of the overlay measurement apparatus 10 includes an illumination optical system 110 for illuminating overlay marks on a semiconductor wafer W, an imaging optical system 120 for focusing reflected light from the overlay marks to form an overlay mark image, and an image detector 130 for acquiring the overlay mark image formed by the imaging optical system 120.

[0041] The illumination optical system 110 can be configured using a variety of optical elements. For example, the illumination optical system 110 may include an illumination source 111, a first aperture 115, a beam splitter 116, a second aperture 117, and an objective lens 118. It may also include a lens 113 positioned between the first aperture 115 and the illumination source 111.

[0042] The illumination source 111 may include a light source capable of generating light across a wide wavelength range, and a variable optical filter capable of adjusting the wavelength range of transmitted light.

[0043] The first aperture 115 is a field diaphragm that adjusts the size and shape of the illumination. The position of the first aperture 115 on the optical path and the aperture shape affect the numerical aperture (NA) and depth of focus (DOF), and therefore have an overall impact on the measurement conditions of the overlay measuring instrument, including the total measurement uncertainty (TMU) and tool-induced shift (TIS). The position of the first aperture 115 on the optical path includes its position on a plane perpendicular to the optical axis and its position in a direction perpendicular to the optical axis.

[0044] The beam splitter 116 is positioned between the illumination source 111 and the objective lens 118, and its role is to transmit illumination from the illumination source 111 to the objective lens 118.

[0045] The second aperture 117 is a aperture diaphragm that adjusts the light intensity and aberrations of the illumination. The position and aperture shape of the second aperture 117 in the optical path are related to telecentricity, which affects the tool guidance shift. Therefore, the tool guidance shift can be fine-tuned by adjusting the position and aperture shape of the second aperture 117 in the optical path. The position of the second aperture 117 in the optical path includes a position on a plane perpendicular to the optical axis and a position in a direction perpendicular to the optical axis.

[0046] The position and aperture shape of the first aperture 115 on the light path can be adjusted to maximize the improvement of the overall performance indicators of the overlay measuring device 10, and the position and aperture shape of the second aperture 117 on the light path can be adjusted to fine-tune the tool guidance shift.

[0047] The objective lens 118 focuses illumination onto the measurement position on the surface of the semiconductor wafer W and collects the reflected light at the measurement position. The objective lens 118 is mounted on the lens focus actuator 119. The lens focus actuator 119 is used to adjust the distance between the objective lens 118 and the semiconductor wafer W.

[0048] The imaging optical system 120 can be configured using a variety of optical elements. For example, the imaging optical system 120 may include a third aperture 121 and a tube lens 123. Alternatively, the imaging optical system 120 may use the objective lens 118, second aperture 117, and beam splitter 116 of the illumination optical system 110.

[0049] The third aperture 121 is a aperture diaphragm that adjusts the amount of reflected light and aberrations. The position of the third aperture 121 on the optical path and the aperture shape are related to telecentricity, which affects the tool guidance shift. Therefore, the tool guidance shift can be fine-tuned by adjusting the position of the third aperture 121 on the optical path and the aperture shape. The position of the third aperture 121 on the optical path includes a position on a plane perpendicular to the optical axis and a position in a direction perpendicular to the optical axis.

[0050] In some embodiments, one of the second aperture 117 and the third aperture 121 may be omitted. The overlay measuring device 10 may be an Infinite Corrected Optical System. The aperture diaphragms, the second aperture 117 and the third aperture 121, can be installed in the Infinite Corrected section where light rays travel parallel to each other.

[0051] The objective lens 118 collects light reflected from the semiconductor wafer W. The light collected by the objective lens 118 passes through the beam splitter 116 and is then focused to the image detector 130 by the tube lens 123.

[0052] The image detector 130 receives reflected light from the overlay mark due to illumination and generates an overlay mark image. The image detector 130 may be a CCD camera or a CMOS camera.

[0053] The aperture shapes of the first aperture 113, the second aperture 117, and the third aperture 121 can be selected from circular, square, ring-shaped, and cross-shaped. The first to third apertures 113, 117, and 121 are mounted on a transport device (not shown) that allows them to be moved in a direction parallel to the optical axis and on a plane perpendicular to the optical axis, so that their position on the optical path of the aperture can be adjusted.

[0054] The first to third apertures 113, 117, and 121 may be variable apertures. As variable apertures, iris-type or plate-type variable apertures can be used.

[0055] An iris-type variable aperture is a variable aperture capable of adjusting the diameter of a circular opening. An iris-type variable aperture may include, for example, a plurality of aperture blades arranged in a superposition such that a circular opening is formed in the center, and a cam member that rotates these aperture blades to change the diameter of the opening.

[0056] A plate-type variable aperture can be a rotating circular plate or a linearly moving rectangular plate with various aperture shapes. The circular plate can be rotated using a motor to change the aperture shape along the optical path. Similarly, the rectangular plate can be linearly moved using a linear actuator to change the aperture shape along the optical path.

[0057] Figure 6 shows an example of a plate-type variable aperture. As shown in Figure 6, a plate-type variable aperture has the advantage of being able to use a variety of aperture shapes that are difficult to achieve with an iris-type variable aperture, such as square, ring-shaped, and cross-shaped apertures, in addition to circular ones.

[0058] Some of the first to third apertures 113, 117, and 121 may be set up so that their positions can be adjusted. Some of the first aperture 113, second aperture 117, and third aperture 121 may be variable apertures.

[0059] Figure 7 is a flowchart of an optimization method for an overlay measuring device according to one embodiment of the present invention. As shown in Figure 7, the optimization method for an overlay measuring device according to one embodiment of the present invention includes the steps of: measuring an initial performance index (in the initial parameter combination) using an initial parameter combination (related) based on the positions and aperture shapes of a plurality of apertures (S1); automatically obtaining an optimal parameter combination (related) based on the positions and aperture shapes of a plurality of apertures based on the initial performance index (S2); and changing the positions and aperture shapes of a plurality of apertures according to the optimal parameter combination (S3).

[0060] The controller 200 of the overlay measurement device 10 can instruct the processor to execute software instructions to perform all or part of the steps in Figure 7. It is preferable that the entire step is instructed by the controller 200 so that human intervention can be minimized.

[0061] First, we will describe step (S1) of measuring the initial performance index of the overlay measuring device (in the initial parameter combination) using a combination of (related) initial parameters based on the positions and aperture shapes of multiple apertures.

[0062] The initial parameter combination can be included in the recipe information received by the controller 200 of the overlay measuring device 10. The initial parameter combination includes information about the aperture shape and position of the first aperture 113, the second aperture 117, and the third aperture 121. In the case of an iris-type variable aperture, it may include information about the diameter of the aperture and the position of the variable aperture aperture on the optical path, i.e., the position in the direction parallel to the optical axis and the position on the plane perpendicular to the optical axis. In the case of a plate-type variable aperture, it may include information about the aperture selected from among multiple apertures and information about the position of the aperture on the optical path. The controller 200 transmits a control signal to the imaging system 100 that includes information about the aperture shape and position of the first to third apertures 113, 117, and 121 based on the initial parameter combination.

[0063] In this step, the initial performance indicators of the overlay measurement device are measured at at least one location on the semiconductor wafer on which the overlay mark is formed, with the aperture shapes and positions of the first to third apertures 113, 117, and 121 adjusted according to the initial parameter combination. Performance indicators that can be used include the accuracy of the overlay measurement device, overall measurement uncertainty, tool-guided shift, movement, acquisition, and measurement time. Statistical values ​​such as the average and 3-sigma values ​​of these can also be used as performance indicators. For tool-guided shift, the 3-sigma value, which is a statistical value of tool-guided shift values ​​measured at multiple locations, is primarily used as a performance indicator.

[0064] Next, we will describe step (S2) of automatically obtaining the optimal combination of (related) parameters based on the positions and aperture shapes of multiple apertures.

[0065] In this step, based on the initial performance indicators obtained in step S1, the optimal combination of (related) parameters based on the positions and aperture shapes of multiple apertures is automatically acquired.

[0066] This step can be performed in various ways. For example, a decision formula can be generated to determine whether optimization is possible, and the optimal combination of parameters for multiple aperture positions and aperture shapes can be searched while changing the positions and aperture shapes of multiple apertures.

[0067] The optimal parameter combination can be found using performance metrics. By assigning weights to each performance metric, the parameter combination that minimizes the sum of the weighted performance metrics can be selected as the optimal parameter combination. If the parameter combination includes a small number of parameters, various parameters can be changed simultaneously; otherwise, only one parameter can be changed sequentially.

[0068] The parameters can be changed based on initial performance indicators. For example, based on the initial performance indicators, the aperture shape and position of the first aperture 115 can be optimized to improve the overall performance indicators of the overlay measuring device, such as accuracy, overall measurement uncertainty, tool guidance shift, movement, acquisition, and measurement time, and then the aperture shapes and positions of the second aperture 117 and the third aperture 121 can be adjusted to precisely control the tool guidance shift.

[0069] More specifically, first, performance indicators are obtained for each aperture shape of the first aperture 115. Weights are then assigned to each performance indicator, and the aperture shape of the first aperture 115 that minimizes the sum of these weighted performance indicators can be found as the optimal aperture shape. The optimal position of the first aperture 115 can also be found using the same method. Furthermore, the optimal aperture shape and position can be found while simultaneously changing both the aperture shape and position of the first aperture 115.

[0070] Next, the position and aperture shape of the second aperture 117 can be repeatedly changed, individually or simultaneously, until the tool-guided shift is minimized or the specifications are satisfied.

[0071] Next, the position and aperture shape of the third aperture 121 can be repeatedly changed, individually or simultaneously, until the tool-guided shift is minimized or the specifications are satisfied.

[0072] Such repetitive processes can be performed automatically.

[0073] Furthermore, this step can also be performed using a machine learning model configured to output optimal parameter combinations (related) based on multiple aperture positions and aperture shapes, based on performance metrics. That is, a machine learning model can be trained using multiple initial performance metrics and the optimal parameter combinations corresponding to these initial performance metrics as training data, and the optimal parameter combinations can be obtained by inputting the initial performance metrics into the trained machine learning model. The actual optimal parameter combinations used for training can be obtained through the iterative process described above. Using a machine learning model has the advantage of eliminating the need for repeated measurements. Measurements can be performed using the optimal parameter combinations obtained using the machine learning model, and at this time, it is sufficient to check whether the calculated performance metrics satisfy the specifications, thus reducing the number of measurements.

[0074] Next, we will describe the step (S3) of changing the position and aperture shape of multiple apertures according to the optimal combination of parameters.

[0075] In this step, the controller 200 generates a control signal based on the optimal parameter combination acquired in step S2 and transmits it to the imaging system 100. As a result, the position and aperture shape of each aperture are adjusted according to the optimal parameter combination.

[0076] The embodiments described above merely illustrate preferred embodiments of the present invention, and the scope of the present invention is not limited to the described embodiments. Various modifications, alterations, or substitutions can be made by those skilled in the art within the scope of the technical idea and claims of the present invention, and such embodiments should be understood to fall within the scope of the present invention. [Explanation of Symbols]

[0077] 10 Overlay measuring device 100 Imaging Systems 110 Illumination optical system 115 First aperture 117 Second aperture 120 Imaging Optical System 121 Third aperture 130 Image detectors 200 controllers

Claims

1. A method for optimizing an overlay measuring device by adjusting at least one of the positions and aperture shapes of a plurality of apertures arranged on the optical path of the overlay measuring device, a) A step of measuring an initial performance index for at least one location on a semiconductor wafer on which an overlay mark is formed, using a plurality of initial parameter combinations based on the position and aperture shape of the aperture, b) A step of automatically obtaining an optimal combination of multiple aperture positions and aperture shapes based on the initial performance index, c) A method for optimizing an overlay measuring device, comprising the step of changing the position and aperture shape of a plurality of apertures according to the optimal parameter combination.

2. In step b) above, The method for optimizing an overlay measuring device according to claim 1, wherein the optimal parameter combination is obtained by inputting the initial performance index into a machine learning model configured to output the optimal parameter combination.

3. In step b) above, the step of automatically obtaining the optimal parameter combination is, A step of obtaining a performance index for each of the multiple parameter combinations based on the positions and aperture shapes of the multiple apertures for each parameter combination, A step of assigning weights to the performance indicators for each parameter combination, A method for optimizing an overlay measuring device according to claim 1, comprising the step of selecting one parameter combination from among the plurality of parameter combinations that minimizes the sum of the weighted performance indicators as the optimal parameter combination.

4. The method for optimizing an overlay measuring device according to claim 1, wherein the performance indicators include at least one of accuracy, total measurement uncertainty (TMU), tool-induced shift (TIS), move, acquire and measure (MAM) time, and statistical values ​​of each thereof.

5. The method for optimizing an overlay measuring apparatus according to claim 1, wherein the aperture includes at least one field stop and at least one aperture stop.

6. The method for optimizing an overlay measuring device according to claim 5, wherein the overlay measuring device is an Infinite Corrected Optical System, and at least one of the aperture diaphragms is installed in an Infinite Correction section where light rays travel in parallel.

7. The overlay measurement apparatus includes an illumination source that generates light, an objective lens that receives light and directs it toward a semiconductor wafer and collects the light reflected from the semiconductor wafer, and an image detector that detects overlay marks formed on the semiconductor wafer from the collected light and generates an overlay mark image. The method for optimizing an overlay measuring device according to claim 6, wherein at least one of the aperture diaphragms is positioned between the image detector and the objective lens of the overlay measuring device.

8. The method for optimizing an overlay measuring device according to claim 1, wherein the aperture shape of the aperture is selected from circular, square, ring-shaped, and cross-shaped.

9. The method for optimizing an overlay measuring device according to claim 1, wherein at least one of the plurality of apertures is a variable aperture.

10. The method for optimizing an overlay measuring device according to claim 9, wherein at least one of the variable apertures is an iris-type variable aperture whose aperture diameter is changed.

11. The method for optimizing an overlay measuring device according to claim 9, wherein at least one of the variable apertures comprises a plate having a plurality of apertures of different shapes, and is configured to change the arrangement of the apertures on the optical path by rotating or linearly moving the plate.

12. An overlay measuring apparatus comprising an imaging system including a plurality of apertures arranged on an optical path for acquiring an overlay mark image, and a controller communicatively coupled to the imaging system, The controller includes at least one memory containing instruction words, and a processor configured to execute the instruction words contained in the at least one memory, wherein the processor executes the instruction words, a) A step of measuring the initial performance index of the overlay measuring device for at least one position on a semiconductor wafer on which an overlay mark to be measured is formed, using a plurality of initial parameter combinations based on the position and aperture shape of the aperture, b) A step of automatically obtaining an optimal combination of multiple aperture positions and aperture shapes based on the initial performance index, c) An overlay measuring device that performs the step of changing the position and aperture shape of a plurality of apertures according to the optimal parameter combination.

13. The overlay measuring apparatus according to claim 12, wherein the performance indicators include at least one of accuracy, total measurement uncertainty (TMU), tool-induced shift (TIS), move, acquire and measure (MAM) time, and statistical values ​​of each thereof.

14. The overlay measuring apparatus according to claim 12, wherein the aperture includes at least one field stop and at least one aperture stop.

15. The overlay measuring device according to claim 14, wherein the overlay measuring device is an Infinite Corrected Optical System, and at least one of the aperture diaphragms is installed in an Infinite Correction section where light rays travel in parallel.

16. The overlay measuring device, A light source that generates light, An objective lens that receives light, directs the light toward a semiconductor wafer, and collects the light reflected from the semiconductor wafer, Includes an image detector that detects overlay marks formed on the semiconductor wafer from collected light and generates an overlay mark image, The overlay measuring device according to claim 15, wherein at least one of the aperture diaphragms is positioned between the image detector and the objective lens of the overlay measuring device.

17. The overlay measuring device according to claim 12, wherein the aperture shape of the aperture is selected from circular, square, ring-shaped, and cross-shaped.

18. The overlay measuring device according to claim 12, wherein at least one of the plurality of apertures is a variable aperture.

19. The overlay measuring device according to claim 18, wherein at least one of the variable apertures is an iris-type variable aperture whose aperture diameter is changed.

20. The overlay measuring device according to claim 18, wherein at least one of the variable apertures comprises a plate having a plurality of apertures of different shapes, and is configured to change the arrangement of the apertures on the optical path by rotating or linearly moving the plate.

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