Target selection method of overlay metrology device and target selection system of overlay metrology device

Abstract

The present invention relates to a method for selecting a sample target of an overlay. According to an embodiment of the present invention, provided is a method for selecting a target of an overlay metrology device. The method for selecting a target of an overlay measurement device comprises: (a) a step for selecting, as acquisition targets, a plurality of overlay targets formed on a wafer; (b) a step for performing a suitability evaluation on each of a plurality of evaluation samples formed of different targets among the acquisition targets, and thereby selecting at least one candidate sample among the plurality of evaluation samples; and (c) a step for selecting targets constituting the candidate samples as metrology targets to be used in a field map of an overlay metrology recipe.

Description

Target selection method for overlay measuring devices and target selection system for overlay measuring devices

[0001] The present invention relates to optimization of an overlay measurement device for a wafer, and more particularly, to a target selection method for an overlay measurement device and a target selection 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] At this time, the best results can be obtained if all patterns formed on the top of the wafer are detected, but a problem arises in that it takes a long time to detect all patterns formed on the top of the wafer.

[0006] Accordingly, a sample map is created by extracting a field containing some representative patterns among all patterns formed on the top of the wafer and performing measurements, but there is a problem of difficulty in selecting a representative pattern because there is no clear standard for selecting a pattern that has the most similar value to all patterns formed on the wafer.

[0007] The present invention aims to solve various problems including the above-mentioned problems, and provides a method for selecting a target for an overlay measurement device and a system for selecting a target for an overlay measurement device, which can select a sample map that can have the most similar results to a map measuring all patterns formed on a wafer by repeatedly performing a suitability evaluation so that the most similar representative pattern that can replace all patterns formed on a wafer can be selected. 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 selecting a target of an overlay measurement device is provided. The method for selecting a target of an overlay measurement device may include: (a) selecting a plurality of overlay targets formed on a wafer as acquisition targets; (b) performing a suitability evaluation on a plurality of evaluation samples formed as different targets among the acquisition targets, thereby selecting at least one candidate sample among the plurality of evaluation samples; and (c) selecting targets constituting the candidate samples as measurement targets to be used in a field map of an overlay measurement recipe.

[0009] According to one embodiment of the present invention, in the step (b), the step (b-1) includes: generating the plurality of evaluation samples formed by combinations of different targets from among the remaining targets, excluding at least one target from among the acquisition targets selected in the previous step; (b-2) performing the suitability evaluation on each of the plurality of evaluation samples; (b-3) selecting the candidate samples in a preset number in the order of the suitability evaluation from among the plurality of evaluation samples; and (b-4) re-selecting targets constituting the candidate samples as acquisition targets; and the steps (b-1) to (b-4) may be sequentially repeated.

[0010] According to one embodiment of the present invention, the step (c) may select the candidate sample having the best result of the suitability evaluation among the candidate samples selected in the step (b) as the measurement target.

[0011] According to one embodiment of the present invention, in the step (b), the suitability evaluation may be performed by a parameter evaluation calculated as an overlay modeling result value of the plurality of evaluation samples and an overlay measurement evaluation calculated as a difference between the acquisition target and targets constituting the plurality of evaluation samples.

[0012] According to one embodiment of the present invention, in the step (b), the parameter evaluation of the suitability evaluation may calculate an average and a standard deviation of the plurality of element values ​​calculated through a plurality of element values ​​affecting the overlay measurement of the plurality of overlay targets formed on the wafer and a plurality of element values ​​affecting the overlay measurement of the targets constituting the plurality of evaluation samples, and store the average of the overlay measurement values ​​calculated by excluding at least one element value from the plurality of element values ​​and setting the remaining element values ​​to 0 as a first evaluation value, and store the standard deviation of the overlay measurement values ​​as a second evaluation value, and the overlay measurement evaluation of the suitability evaluation may store an average of difference values ​​calculated through the overlay calculation values ​​calculated from the plurality of overlay targets formed on the wafer and the overlay calculation values ​​calculated from the targets constituting the plurality of evaluation samples as a third evaluation value, and store the standard deviation of the difference values ​​as a fourth evaluation value.

[0013] According to one embodiment of the present invention, in the step (b), the parameter evaluation is performed to sort the order of the plurality of evaluation samples and assign a set score according to the order, the overlay measurement evaluation is performed to sort the order of the plurality of evaluation samples and assign a set score according to the order, the scores of each evaluation sample are added up, and at least one evaluation sample among the plurality of evaluation samples can be selected according to the added score.

[0014] According to one embodiment of the present invention, after step (c), the method may include a step of comparing a learning wafer used to select the measurement target in steps (a), (b), and (c) with a comparison wafer that did not perform steps (a), (b), and (c), thereby verifying whether the measurement target is a target to be used in a field map of the overlay measurement recipe.

[0015] According to one embodiment of the present invention, the step (d) may include: (d-1) performing the suitability evaluation on the measurement target selected in the step (c) among the plurality of overlay targets formed on the learning wafer; (d-2) performing the suitability evaluation on a target formed at the same position as the measurement target selected in the step (c) among the plurality of overlay targets formed on the comparison wafer; (d-3) performing the suitability evaluation on an arbitrary target among the plurality of overlay targets formed on the comparison wafer; and (d-4) comparing the results of the suitability evaluations calculated in the steps (d-1), (d-2), and (d-3).

[0016] According to one embodiment of the present invention, a target selection system of an overlay measurement device is provided. The target selection system of the overlay measurement device may include: an acquisition target selection unit that selects a plurality of overlay targets formed on a wafer as acquisition targets; a candidate sample selection unit that performs a suitability evaluation on a plurality of evaluation samples formed as different targets among the acquisition targets, thereby selecting at least one candidate sample from among the plurality of evaluation samples; and a measurement target selection unit that selects measurement targets to be used in a field map of an overlay measurement recipe from among targets constituting the candidate samples.

[0017] According to one embodiment of the present invention, the candidate sample selection unit may include an evaluation sample generation unit that generates a plurality of evaluation samples formed by combinations of different targets from among the remaining targets, excluding at least one target from among the acquisition targets selected in the previous step; an evaluation unit that performs the suitability evaluation on each of the plurality of evaluation samples; a sorting unit that selects a preset number of candidate samples from among the plurality of evaluation samples in the order of the suitability evaluation; and a conversion unit that re-selects targets constituting the candidate samples as acquisition targets.

[0018] According to one embodiment of the present invention, the measurement target selection unit can select, as the measurement target, a candidate sample having the best result in the suitability evaluation among the candidate samples selected by the candidate sample selection unit.

[0019] According to one embodiment of the present invention, the candidate sample selection unit can perform the suitability evaluation consisting of a parameter evaluation calculated as an overlay modeling result value of the plurality of evaluation samples and an overlay measurement evaluation calculated as a difference between the acquisition target and targets constituting the plurality of evaluation samples.

[0020] According to one embodiment of the present invention, the parameter evaluation of the suitability evaluation may calculate an average and a standard deviation of the plurality of element values ​​calculated through a plurality of element values ​​affecting the overlay measurement of the plurality of overlay targets formed on the wafer and a plurality of element values ​​affecting the overlay measurement of the targets constituting the plurality of evaluation samples, and store the average of the overlay measurement values ​​calculated by excluding at least one element value from the plurality of element values ​​and setting the remaining element values ​​to 0 as a first evaluation value, and store the standard deviation of the overlay measurement values ​​as a second evaluation value, and the overlay measurement evaluation of the suitability evaluation may store an average of difference values ​​calculated through the overlay calculation values ​​calculated from the plurality of overlay targets formed on the wafer and the overlay calculation values ​​calculated from the targets constituting the plurality of evaluation samples as a third evaluation value, and store the standard deviation of the difference values ​​as a fourth evaluation value.

[0021] According to one embodiment of the present invention, the candidate sample selection unit may perform the parameter evaluation to sort the order of the plurality of evaluation samples and assign a set score according to the order, perform the overlay measurement evaluation to sort the order of the plurality of evaluation samples and assign a set score according to the order, and add up the scores of each evaluation sample to select at least one evaluation sample from among the plurality of evaluation samples according to the summed score.

[0022] According to one embodiment of the present invention, the acquisition target selection unit, the candidate sample selection unit, and the measurement target selection unit may include a verification unit that compares a learning wafer used to select the measurement target with a comparison wafer for which the measurement target has not been selected, and verifies whether the measurement target is a target to be used in a field map of the overlay measurement recipe.

[0023] According to one embodiment of the present invention, the verification unit may include a first evaluation unit that performs the suitability evaluation on a measurement target selected by the measurement target selection unit among a plurality of overlay targets formed on the learning wafer; a second evaluation unit that performs the suitability evaluation on a target formed at the same position as the measurement target selected by the measurement target selection unit among a plurality of overlay targets formed on the comparison wafer; a third evaluation unit that performs the suitability evaluation on an arbitrary target among a plurality of overlay targets formed on the comparison wafer; and a comparison unit that compares the results of the suitability evaluations produced by the first evaluation unit, the second evaluation unit, and the third evaluation unit.

[0024] According to some embodiments of the present invention as described above, it is possible to select the most similar representative pattern that can replace all patterns formed on a wafer, and to select a sample map that can have the most similar results to a map that measures all patterns formed on a wafer through the selected patterns.

[0025] Accordingly, overlay measurement can be performed using a recipe generated based on a sample map, resulting in reduced wafer overlay measurement time and increased productivity. Of course, the scope of the present invention is not limited by these effects.

[0026] FIG. 1 is a schematic diagram illustrating an overlay measuring device according to one embodiment of the present invention.

[0027] FIG. 2 is a top view showing a plurality of overlay targets of a wafer mounted on a stage of the overlay measurement device of FIG. 1.

[0028] Fig. 3 is a drawing showing the control unit of the overlay measuring device of Fig. 1.

[0029] Figures 4 to 7 are flowcharts showing a target selection method of an overlay measurement device according to various embodiments of the present invention.

[0030] FIG. 8 is a drawing showing one embodiment of a target selection method of an overlay measuring device according to the present invention.

[0031] FIG. 9 is a drawing schematically showing a verification step (d) in a target selection method of an overlay measuring device according to another embodiment of the present invention.

[0032] FIG. 10 is a drawing showing parameter evaluation of suitability assessment in a target selection method of an overlay measuring device according to the present invention.

[0033] FIG. 11 is a drawing showing an overlay measurement evaluation of suitability in a target selection method of an overlay measurement device according to the present invention.

[0034] Figure 12 is a table showing a suitability evaluation for a plurality of evaluation samples in a target selection method of an overlay measuring device according to the present invention.

[0035] FIG. 13 is a schematic diagram illustrating a target selection system of an overlay measurement device according to one embodiment of the present invention.

[0036] FIG. 14 is a schematic diagram illustrating a target selection system of an overlay measurement device according to another embodiment of the present invention.

[0037] Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0038] 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.

[0039] 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.

[0040] FIG. 1 is a schematic diagram showing an overlay measurement device (1000) according to one embodiment of the present invention, FIG. 2 is a top view showing a plurality of overlay targets of a wafer mounted on a stage (500) of the overlay measurement device (1000) of FIG. 1, and FIG. 3 is a diagram showing a control unit (400) of the overlay measurement device (1000) of FIG. 1.

[0041] As illustrated in FIGS. 1 and 2, the overlay measurement device (1000) is a device that detects a plurality of overlay targets (T) formed on a wafer (W) and measures alignment errors for two layers. At this time, the plurality of overlay targets (T) may include a first overlay key and a second overlay key formed on different layers, respectively.

[0042] 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.

[0043] 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.

[0044] 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).

[0045] The light source unit (100) can direct illumination to a plurality of overlay targets (T) formed on a wafer (W). Specifically, the light source unit (100) can be configured to direct illumination to a plurality of overlay 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.

[0046] 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).

[0047] 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.

[0048] 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 overlay 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.

[0049] 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 overlay targets (T).

[0050] 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).

[0051] 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.

[0052] 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 at one point among a plurality of overlay targets (T), a lens focus actuator (220) that adjusts the distance between the objective lens (210) and the plurality of overlay targets (T) at the measurement position, and a pinhole (230) that passes light reflected at the measurement position.

[0053] 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.

[0054] The objective lens (210) can be installed on a lens focus actuator (220).

[0055] 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 overlay targets (T).

[0056] 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).

[0057] 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.

[0058] 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.

[0059] 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).

[0060] 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.

[0061] The detection unit (300) can capture the beam reflected from a plurality of overlay targets (T) and passing through the beam splitter (140) to obtain images of the first overlay key and the second overlay key.

[0062] The detection unit (300) may include an optical detector capable of measuring a beam reflected from a plurality of overlay targets (T), and for example, the optical detector may include a charge-coupled device (CCD) that converts light into charge 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.

[0063] 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).

[0064] Additionally, the detection unit (300) can measure a global mark to confirm the correct position of the wafer (W).

[0065] 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 overlay targets (T) of the wafer (W) can be measured from the upper lens unit (200).

[0066] 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 overlay targets (T) and collect the reflected beams, control the operation of the lens focus actuator (220) to focus the light on a plurality of overlay 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 targets are positioned below the lens unit (200).

[0067] The control unit (400) may include a storage unit (440) that stores the overlay measurement image measured by the detection unit (300).

[0068] The storage unit (440) may include a storage unit (440) that stores commands, programs, logic, etc. that control the operation of each component of the overlay measuring device (1000), and components may be added, changed, or deleted as needed.

[0069] The storage unit (440) may include an automatic measurement program (ARO, Auto Recipe Optimization) that automatically optimizes and calculates measurement options of an overlay measurement recipe, including a filter, aperture numerical aperture (NA), focus, pinhole, etc.

[0070] In addition to the optimized recipe information regarding the operation of the measuring device, the automatic measurement program may include information about the measuring device and information about the wafer (W) introduced into the overlay measuring device (1000). Accordingly, the automatic measurement program may automatically derive optimal options through the optimized recipe information, the measuring device information, and the measurement target position information.

[0071] The control unit (400) may include an acquisition target selection unit (450), a candidate sample selection unit (460), a measurement target selection unit (470), and a verification unit (480). At this time, each component of the control unit (400) may have its own individual process, and may exchange data or signals in real time from one component to another.

[0072] Each configuration of the control unit (400) will be described later in the target selection system of the overlay measurement device to be described later.

[0073] 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.

[0074] 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 overlay targets (T).

[0075] FIG. 4 and FIG. 5 are flowcharts showing a target selection method of an overlay measurement device according to embodiments of the present invention, and FIG. 8 is a drawing schematically showing a target selection method of an overlay measurement device.

[0076] According to one embodiment of the present invention, a method for selecting a target of an overlay measurement device may include, as illustrated in FIG. 4, (a) a step of selecting a plurality of overlay targets (T) as acquisition targets, (b) a step of selecting a candidate sample, and (c) a step of selecting a measurement target.

[0077] Specifically, the above step (a) is a step of selecting a plurality of overlay targets (T) formed on a wafer (W) as acquisition targets.

[0078] For example, when a wafer (W) for overlay measurement is introduced into an overlay measurement device (1000), information about various wafers (W) including quantity information and position information for a plurality of overlay targets (T) can be stored.

[0079] For example, a plurality of n overlay targets (T) can be formed on a wafer (W), and n overlay targets including position information can be selected as acquisition targets (O).

[0080] More specifically, as shown in FIG. 8, a plurality of overlay targets (Dense plan) formed on a wafer (W) are formed as marks 1, 2, 3, 4, and 5, and the marks 1, 2, 3, 4, and 5 can become acquisition targets (O).

[0081] As illustrated in FIG. 4, the step (b) is a step of performing a suitability evaluation (FF) on each of a plurality of evaluation samples (SP) formed as different targets among the acquisition targets (O), thereby selecting at least one candidate sample among the plurality of evaluation samples (SP).

[0082] Specifically, as illustrated in FIG. 5, the step (b) may include (b-1) a step of generating a plurality of evaluation samples (SP), (b-2) a step of evaluating suitability, (b-3) a step of selecting a candidate sample (CP), and (b-4) a step of re-selecting the candidate sample (O) as an acquisition target.

[0083] Specifically, the step (b-1) is a step of generating a plurality of evaluation samples (SP) formed by a combination of different targets among the remaining targets, excluding at least one target among the acquisition targets (O) selected in the previous step.

[0084] For example, in the step (b-1) above, a plurality of evaluation samples (SP) are formed of a plurality of overlay targets, and at this time, the number of targets included in each of the plurality of evaluation samples (SP) is the same, but may be formed of targets formed at different locations.

[0085] More specifically, as shown in FIG. 8, in the step (b-1), five evaluation samples can be selected, including marks 1, 2, 3, 4 as a first evaluation sample (SP1), marks 1, 2, 3, 5 as a second evaluation sample (SP2), marks 1, 2, 4, 5 as a third evaluation sample (SP3), marks 1, 3, 4, 5 as a fourth evaluation sample (SP4), and marks 2, 3, 4, 5 as a fifth evaluation sample (SP5), excluding one target among marks 1, 2, 3, 4, 5.

[0086] The above step (b-2) is a step of performing a suitability assessment (FF) on each of a plurality of evaluation samples (SP), and is a step of performing an evaluation on each evaluation sample by applying a preset suitability assessment (FF) to the plurality of evaluation samples (SP).

[0087] For example, as illustrated in FIG. 8, in step (b-2), a suitability evaluation (FF) can be performed on each of the first evaluation sample (SP1), the second evaluation sample (SP2), the third evaluation sample (SP3), the fourth evaluation sample (SP4), and the fifth evaluation sample (SP5).

[0088] Accordingly, the suitability evaluation result for the first evaluation sample (SP1) can be calculated as 4, the suitability evaluation result for the second evaluation sample (SP2) can be calculated as 2, the suitability evaluation result for the third evaluation sample (SP3) can be calculated as 3, the suitability evaluation result for the fourth evaluation sample (SP4) can be calculated as 1, and the suitability evaluation result for the fifth evaluation sample (SP5) can be calculated as 5. The specific calculation process of the suitability evaluation (FF) will be described later.

[0089] The above step (b-3) is a step of selecting a preset number of candidate samples (CP) in the order of suitability evaluation among multiple evaluation samples (SP).

[0090] Specifically, in the step (b-3) above, based on the results of the multiple evaluation samples (SP) produced by the suitability assessment (FF), the multiple evaluation samples (SP) can be arranged in an order suitable for the target to be used in the field map of the overlay measurement recipe.

[0091] The above step (b-3) is a step for aligning multiple evaluation samples (SP) based on the results from the above step (b-2) and selecting candidate samples (CP) suitable for the target to be used in the field map. At this time, the lower the score produced as a result of the suitability evaluation (FF), the higher the suitability for the target to be used in the field map can be determined.

[0092] More specifically, as shown in FIG. 8, in step (b-3), when the number of candidate samples (CP) selected is 2, the fourth evaluation sample (SP4) and the second evaluation sample (SP2) with lower output values ​​can be selected as candidate samples (CP).

[0093] The above step (b-4) is a step of re-selecting the targets constituting the candidate sample (CP) as acquisition targets (O).

[0094] For example, as illustrated in FIG. 8, in the step (b-4), marks 1, 2, 3, and 5, which are targets constituting the second evaluation sample (SP2) selected as the candidate sample (CP) in the previous step, and marks 1, 3, 4, and 5, which are targets constituting the fourth evaluation sample (SP4), can be selected as respective acquisition targets (O).

[0095] At this time, as illustrated in Fig. 5, step (b) may be repeated until a preset quantity of measurement targets are selected. That is, steps (b-1) to (b-4) may be sequentially repeated.

[0096] For example, as illustrated in FIG. 8, after the above (b-4), the step (2b-1) may include regenerating the plurality of evaluation samples (SP) formed by combinations of different targets among marks 1, 2, 3, and 5 obtained in the above (b-4) step.

[0097] In the above step (2b-1), excluding one target among the marks 1, 2, 3, and 5 obtained in the above step (b-4), marks 1, 2, and 3 are generated as a 2-1 evaluation sample (SP2-1), marks 1, 2, and 5 are generated as a 2-2 evaluation sample (SP2-2), marks 1, 3, and 5 are generated as a 2-3 evaluation sample (SP2-3), and marks 2, 3, and 5 are generated as a 2-4 evaluation sample (SP2-4), and excluding one target among the marks 1, 3, 4, and 5, marks 1, 3, and 4 are generated as a 4-1 evaluation sample (SP4-1), marks 1, 3, and 5 are generated as a 4-2 evaluation sample (SP4-2), marks 1, 4, and 5 are generated as a 4-3 evaluation sample (SP4-3), and marks 3, 4, and 5 are generated as a 4-4 evaluation sample. You can regenerate the evaluation sample by creating a sample (SP4-4).

[0098] Next, (2b-2) a step of performing a suitability evaluation (FF) on each of the re-generated evaluation samples and performing an evaluation on each evaluation sample by applying a preset suitability evaluation (FF) to a plurality of evaluation samples (SP), (2b-3) a step of selecting a preset number of candidate samples (CP) in the order of suitability evaluation among the plurality of evaluation samples (SP), and (2b-4) a step of re-selecting targets constituting the candidate samples (CP) as acquisition targets (O).

[0099] The above step (c) is a step for selecting targets constituting candidate samples (CP) as measurement targets to be used in a field map of an overlay measurement recipe, as illustrated in FIG. 4. Specifically, the step (c) may select a candidate sample having the best result in a suitability evaluation (FF) among the candidate samples (CP) selected in the step (b) as the measurement target.

[0100] Before the above step (c), the step (b) is repeated while removing targets one by one until the number of targets constituting the plurality of evaluation samples (SP) is reduced by a preset number, and when the number is reduced by the preset number in the step (c), the remaining targets can be selected as measurement targets (OP).

[0101] For example, as illustrated in Fig. 8, marks 1, 2, and 5 of the 2-2 evaluation sample (SP2-2) with the best results in the suitability evaluation (FF) among the acquisition targets (O) selected in the previous step can be selected as measurement targets (OP).

[0102] FIG. 6 and FIG. 7 are flowcharts showing a target selection method of an overlay measurement device according to other embodiments of the present invention, and FIG. 9 is a drawing schematically showing a verification step (d) in a target selection method of an overlay measurement device according to other embodiments of the present invention.

[0103] As illustrated in FIG. 6, a method for selecting a target of an overlay measurement device according to another embodiment of the present invention may include a step of (d) verifying a measurement target.

[0104] Prior to the above step (d), a step of preparing a wafer required for verification may be included.

[0105] The step (d) above is a step for verifying whether the measurement target (OP) is a target to be used in the field map of the overlay measurement recipe by comparing the training set (TS) used to select the measurement target (OP) in the steps (a), (b), and (c) after the step (c) with the comparison wafer (VS, Validation set) that did not perform the steps (a), (b), and (c).

[0106] Specifically, as illustrated in FIG. 7, the step (d) may include (d-1) a step of performing a suitability evaluation (FF) on a measurement target (OP) of a learning wafer (TS), (d-2) a step of performing a suitability evaluation (FF) on a target corresponding to a measurement target in a comparison wafer (VS), (d-3) a step of performing a suitability evaluation (FF) on an arbitrary target of the comparison wafer (VS), and (d-4) a step of comparing.

[0107] The above step (d-1) is a step of performing a suitability evaluation (FF) on the measurement target (OP) selected in the above step (c) among the multiple overlay targets formed on the learning wafer (TS).

[0108] Accordingly, in the step (d-1), a first verification value can be calculated as a suitability evaluation (FF) for the measurement target (OP) in the learning wafer (TS).

[0109] For example, as illustrated in Fig. 9, by performing steps (a), (b), and (c), a suitability evaluation (FF) can be performed on a learning wafer (TS) in which a measurement target (OP) is selected. At this time, the result value can be the first Fitness value, which can be the first verification value.

[0110] The above step (d-2) is a step for performing a suitability evaluation (FF) on a target formed at the same location as the measurement target (OP) selected in the above step (c), among a plurality of overlay targets formed on a comparison wafer (VS).

[0111] Accordingly, in the step (d-2), a suitability evaluation (FF) can be performed on a target at a position corresponding to the measurement target (OP) in the comparison wafer (VS) to produce a second verification value.

[0112] For example, as illustrated in Fig. 9, in a comparison wafer (VS) that has not performed steps (a), (b), and (c), a suitability evaluation (FF) can be performed on a target at the same location as the measurement target (OP) selected in the learning wafer (TS). At this time, the result value can be the second fitness value, which can be the second verification value.

[0113] The above step (d-3) is a step of performing a suitability evaluation (FF) on an arbitrary target among a plurality of overlay targets formed on a comparison wafer (VS).

[0114] Accordingly, in the step (d-3), a suitability evaluation (FF) can be performed on a target preset on a comparison wafer (VS) or on an arbitrary target to produce a third verification value.

[0115] For example, as illustrated in Fig. 9, in a comparison wafer (VS) that has not performed steps (a), (b), and (c), a suitability evaluation (FF) can be performed on a target at a location specified by an automatic recipe optimization program. At this time, the resulting value can be the third fitness value, which can be the third verification value.

[0116] The above step (d-4) is a step of comparing the results of the suitability assessment produced in the above steps (d-1), (d-2), and (d-3).

[0117] For example, the step (d-4) is a step of comparing the first verification value, the second verification value, and the third verification value. At this time, in the step (d-4), if the first verification value is calculated to be lower than the second verification value and the third verification value, and the result of the suitability evaluation (FF) is calculated to be the best, the measurement target (OP) selected in the step (c) can be determined as the sample target with the highest reliability among the plurality of overlay targets (T).

[0118] At this time, the lower the suitability evaluation (FF) score, the better the suitability result can be judged.

[0119] FIG. 10 is a drawing showing a parameter evaluation of suitability evaluation in a target selection method of an overlay measurement device according to the present invention, FIG. 11 is a drawing showing an overlay measurement evaluation of suitability evaluation, and FIG. 12 is a table showing suitability evaluation for a plurality of evaluation samples.

[0120] In step (b), the suitability assessment may include parameter assessment and overlay measurement assessment.

[0121] The above parameter evaluation can be produced as an overlay modeling result value of multiple evaluation samples (SP).

[0122] Specifically, the above parameter evaluation can calculate the average and standard deviation of the plurality of element values ​​calculated through the plurality of element values ​​affecting the overlay measurement of the plurality of overlay targets (T) formed on the wafer (W) and the plurality of element values ​​affecting the overlay measurement of the targets constituting the plurality of evaluation samples (SP).

[0123] For example, as illustrated in Fig. 10, a plurality of element values ​​(Cofficient) affecting the overlay measurement of an initial sample (Dense) using a plurality of overlay targets (T) formed on a wafer (W) as samples can be calculated, and then a plurality of element values ​​affecting the overlay measurement of an evaluation sample (Plan1) which is a plurality of evaluation samples (SP) can be calculated. Thus, the difference between the plurality of element values ​​corresponding to each of the initial sample and the evaluation sample can be calculated, and the average and standard deviation of each element value can be calculated.

[0124] Next, the parameter evaluation can configure a matrix in which all element values ​​except for the element value (Coefficient) to be confirmed are set to 0 in order to compensate for the difference in element values ​​according to the location of the target formed on the wafer (W).

[0125] Specifically, the parameter evaluation may store the average of the overlay measurement values ​​calculated by setting the remaining element values ​​except for at least one element value among the plurality of element values ​​to 0 as the first evaluation value, and store the standard deviation of the overlay measurement values ​​as the second evaluation value.

[0126] For example, as illustrated in Fig. 10, the other element values ​​except for the first element value (Corff 1) are set to 0, and the other element values ​​except for the nth element value (Corff n) are set to 0, so that the nth overlay value according to the nth element value can be measured. Thus, the average of all overlay values ​​can be calculated as the first evaluation value of the parameter evaluation, and the standard deviation can be calculated as the second evaluation value of the parameter evaluation.

[0127] At this time, in order to check the influence of each of the above multiple element values, they can be converted into numerical values ​​in nanometer units and compared.

[0128] The above multiple element values ​​are errors that may occur during wafer production, and may include an offset value indicating a difference in coordinate values ​​between the center of a reference wafer and the center of a current wafer, a rotation value indicating a degree of rotation from the X-axis or Y-axis, a magnification value indicating a degree of wafer expansion for detecting defects occurring at the wafer edge, and an orthogonality indicating an angle formed by the X-axis and the Y-axis.

[0129] The above overlay measurement evaluation can be calculated as the difference between the acquisition target (O) and the targets constituting the multiple evaluation samples (SP).

[0130] Specifically, the above overlay measurement evaluation can store the average of the difference values ​​calculated through the overlay output values ​​produced from the plurality of overlay targets (T) formed on the wafer (W) and the overlay output values ​​produced from the targets constituting the plurality of evaluation samples (SP) as a third evaluation value, and store the standard deviation of the difference values ​​as a fourth evaluation value.

[0131] For example, as illustrated in FIG. 11, an overlay measurement evaluation may be performed by applying the 3-sigma rule (Mean+3Sigma) to an initial sample (Dense) that is a sample of a plurality of overlay targets (T) formed on a wafer (W), and then, the overlay measurement evaluation may be performed by applying the 3-sigma rule (Mean+3Sigma) to an evaluation sample (Plan1) that is a plurality of evaluation samples (SP). Thus, the average of the differences calculated from the initial sample and the evaluation sample may be calculated as the third evaluation value of the overlay measurement evaluation, and the standard deviation may be calculated as the fourth evaluation value of the overlay measurement evaluation.

[0132] The above 3-sigma rule (Mean+3Sigma) is a rule that indicates that almost all values ​​can fall within the range of 3 * standard deviation (sigma) on either side of the mean (mean).

[0133] Accordingly, the plurality of evaluation samples can be evaluated using the first evaluation value, the second evaluation value, the third evaluation value, and the fourth evaluation value calculated through the parameter evaluation and the overlay measurement evaluation, and at least one evaluation sample can be selected based on the evaluation.

[0134] Specifically, in the step (b), the parameter evaluation may be performed to align the order of a plurality of evaluation samples (SP) and assign a set score according to the order, and the overlay measurement evaluation may be performed to align the order of a plurality of evaluation samples (SP) and assign a set score according to the order.

[0135] At this time, the scores of each evaluation sample are added up, and at least one evaluation sample among multiple evaluation samples (SP) can be selected based on the added score.

[0136] For example, as illustrated in FIG. 12, one evaluation sample may be selected from a total of four evaluation samples including a first evaluation sample (Plan1), a second evaluation sample (Plan2), a third evaluation sample (Plan3), and a fourth evaluation sample (Plan4).

[0137] First, the first evaluation value (PO), which is the average of the above parameter evaluations, was calculated as 1, 2, 3, and 4 points in the order of the first evaluation sample (Plan1), the second evaluation sample (Plan2), the third evaluation sample (Plan3), and the fourth evaluation sample (Plan4).

[0138] In addition, the second evaluation value (PV), which is the standard deviation of the above parameter evaluation, was calculated as 2, 3, 1, and 4 points in the order of the first evaluation sample (Plan1), the second evaluation sample (Plan2), the third evaluation sample (Plan3), and the fourth evaluation sample (Plan4).

[0139] In this way, in the same way, for each evaluation sample, the third evaluation value (MO), which is the average of the overlay measurement evaluation, and the fourth evaluation value (MO), which is the standard deviation of the overlay measurement evaluation, were sorted in order to calculate a score, and the sum of the evaluation values ​​was added up so that the first evaluation sample (Plan1) had the smallest value.

[0140] At this time, the smaller the score produced as a result of the suitability assessment (FF), the higher the suitability for the target to be used in the field map can be determined, and accordingly, the target constituting the first evaluation sample (Plan1) can be selected as the measurement target (OP).

[0141] A target selection system of an overlay measurement device according to one embodiment of the present invention may include an overlay measurement device (1000).

[0142] As described above, the overlay measurement device (1000) may include a light source unit (100), a lens unit (200), a detection unit (300), and a control unit (400), and each component may control the operation of each component of the overlay measurement device (1000) by a processor including commands, programs, logic, etc.

[0143] In addition, the target selection system of the overlay measurement device of the present invention can transmit data or signals to one overlay measurement device (1000) through a user terminal, or can simultaneously transmit data or signals to multiple overlay measurement devices.

[0144] The above user terminal is included in the control unit (400) of the overlay measurement device (1000) and can transmit and receive data with the light source unit (100), lens unit (200), detection unit (300), and other components of the control unit (400) of the overlay measurement device (1000), or the user terminal is configured as a separate device connected to the overlay measurement device (1000) by wire or wirelessly and can transmit and receive data with the overlay measurement device (1000).

[0145] Recipe information regarding the operation of the overlay measurement device (1000) for measuring the characteristics of a wafer (W) can be input from a user through the user terminal. For example, the automatic measurement program can input values ​​for a plurality of parameters for measuring the characteristics of a wafer from a user through the user terminal.

[0146] In addition, the overlay measuring device (1000) operates in conjunction with the user terminal through installed measuring software (e.g., overlay application), and may include commands for operating the overlay measuring device (1000) based on data (e.g., recipe information) received from the user terminal.

[0147] FIGS. 13 and 14 are schematic drawings illustrating a target selection system of an overlay measurement device according to various embodiments of the present invention.

[0148] The target selection system of the overlay measurement device according to one embodiment of the present invention may include an acquisition target selection unit (450), a candidate sample selection unit (460), and a measurement target selection unit (470), as illustrated in FIG. 13.

[0149] The acquisition target selection unit (450) can select a plurality of overlay targets (T) formed on a wafer (W) as acquisition targets.

[0150] The candidate sample selection unit (460) can perform a suitability evaluation (FF) on each of a plurality of evaluation samples (SP) formed as different targets among the acquisition targets (O), thereby selecting at least one candidate sample (CP) among the plurality of evaluation samples (SP).

[0151] The candidate sample selection unit (460) may include an evaluation sample generation unit (461), an evaluation unit (462), a sorting unit (463), and a conversion unit (464).

[0152] The evaluation sample generation unit (461) can generate a plurality of evaluation samples formed by combinations of different targets among the remaining targets, excluding at least one target among the acquisition targets selected in the previous step.

[0153] For example, as illustrated in FIG. 13, the evaluation sample generation unit (461) can generate a plurality of first evaluation samples by a combination of acquisition targets (O) selected by the acquisition target selection unit (450).

[0154] The evaluation unit (462) can perform a suitability evaluation (FF) on each of a plurality of evaluation samples (SP).

[0155] For example, as illustrated in FIG. 13, the evaluation unit (462) can perform a suitability evaluation (FF) on the plurality of first evaluation samples generated by the evaluation sample generation unit (461).

[0156] Specifically, the evaluation unit (462) of the candidate sample selection unit (460) can perform a suitability evaluation (FF) consisting of a parameter evaluation and an acquisition target (O) calculated as overlay modeling result values ​​of a plurality of evaluation samples (SP) and an overlay measurement evaluation calculated as a difference between targets constituting the plurality of evaluation samples (SP).

[0157] At this time, the parameter evaluation may calculate the average and standard deviation of the plurality of element values ​​calculated through the plurality of element values ​​affecting the overlay measurement of the plurality of overlay targets (T) formed on the wafer (W) and the plurality of element values ​​affecting the overlay measurement of the targets constituting the plurality of evaluation samples (SP), and store the average of the overlay measurement values ​​calculated by setting the remaining element values ​​except for at least one element value among the plurality of element values ​​to 0 as the first evaluation value, and store the standard deviation of the overlay measurement values ​​as the second evaluation value.

[0158] In addition, the above overlay measurement evaluation can store the average of the difference values ​​calculated through the overlay output values ​​calculated from the plurality of overlay targets (T) formed on the wafer (W) and the overlay output values ​​calculated from the targets constituting the plurality of evaluation samples (SP) as a third evaluation value, and store the standard deviation of the difference values ​​as a fourth evaluation value.

[0159] The sorting unit (463) can select a preset number of candidate samples (CP) in the order of suitability evaluation (FF) among a plurality of evaluation samples (SP).

[0160] For example, as illustrated in FIG. 13, the sorting unit (463) is a step of sorting a plurality of first evaluation samples in an order suitable for a target to be used in a field map of an overlay measurement recipe, based on the results of the plurality of first evaluation samples produced by the suitability evaluation (FF) in the evaluation unit (462), and selecting at least one first candidate sample. At this time, a preset number of the first candidate samples may be selected.

[0161] Specifically, the sorting unit (463) of the candidate sample selection unit (460) can perform the parameter evaluation to sort the order of a plurality of evaluation samples (SP) and assign a set score according to the order, perform the overlay measurement evaluation to sort the order of a plurality of evaluation samples (SP) and assign a set score according to the order, add up the scores of each evaluation sample, and select at least one evaluation sample among the plurality of evaluation samples (SP) as a candidate sample (CP) according to the summed score.

[0162] The conversion unit (464) can re-select the targets constituting the candidate sample (CP) as acquisition targets.

[0163] For example, as illustrated in FIG. 13, the conversion unit (464) can re-select targets constituting at least one of the first candidate samples re-selected in the sorting unit (463) as acquisition targets (O).

[0164] Next, a plurality of second evaluation samples are generated using the re-selected acquisition targets (O) in the evaluation sample generation unit (461), the evaluation unit (462) calculates a suitability evaluation (FF) score for the plurality of second evaluation samples, and the sorting unit (463) selects a number of at least one second candidate sample in the same manner as when selecting the first candidate sample, and the targets constituting the second candidate sample are re-selected as the acquisition targets (O) in the conversion unit (464).

[0165] The candidate sample selection unit (460) can be repeated until x measurement targets (OP) are selected. That is, the evaluation sample generation unit (461) generates a plurality of m-th evaluation samples, and at this time, the number of targets constituting each evaluation sample among the plurality of m-th evaluation samples can be formed as (nm). Here, n is the total number of targets formed on the wafer (W).

[0166] Next, the evaluation unit (462) calculates a score of the mth suitability evaluation for the plurality of mth evaluation samples, the sorting unit (463) can select at least one mth candidate sample formed by (nm) targets, and the conversion unit (464) can re-select a target of the mth candidate sample formed by (nm) targets as an acquisition target.

[0167] As illustrated in FIG. 13, the measurement target selection unit (470) can select measurement targets to be used in the field map of the overlay measurement recipe from among the targets constituting the candidate sample (CP).

[0168] Specifically, the measurement target selection unit (470) can select the candidate sample with the best result of the suitability evaluation (FF) among the candidate samples (CP) selected by the candidate sample selection unit (460) as the measurement target (OP).

[0169] For example, as illustrated in FIG. 13, the candidate sample selection unit (460) is repeated to remove targets one by one until a predetermined number of targets constituting a plurality of evaluation samples (SP) are set in advance, and when x targets remain in the candidate sample selection unit (460), the target of the mth candidate sample with the best suitability evaluation (FF) can be selected as the measurement target (OP). At this time, the measurement target (OP) is a predetermined number x, and when the number of the plurality of overlay targets (T) formed on the wafer (W) is n, the candidate sample selection unit (460) is repeated m times to reduce the number of targets to x, so x can be (nm).

[0170] As illustrated in FIG. 14, the target selection system of the overlay measurement device according to another embodiment of the present invention may include a verification unit (480).

[0171] The verification unit (480) can compare the learning wafer (TS) used to select the measurement target (OP) in the acquisition target selection unit (450), the candidate sample selection unit (460), and the measurement target selection unit (470) with the comparison wafer (VS) for which the measurement target (OP) has not been selected, to verify whether the measurement target (OP) is a target to be used in the field map of the overlay measurement recipe.

[0172] Specifically, the verification unit (480) may include a first evaluation unit (481) that performs a suitability evaluation (FF) on a measurement target (OP) selected by a measurement target selection unit (470) among a plurality of overlay targets (T) formed on a learning wafer (TS), a second evaluation unit (482) that performs a suitability evaluation (FF) on a target formed at the same position as a measurement target (OP) selected by a measurement target selection unit (470) among a plurality of overlay targets formed on a comparison wafer (VS), a third evaluation unit (483) that performs a suitability evaluation (FF) on an arbitrary target among a plurality of overlay targets formed on a comparison wafer (VS), and a comparison unit (484) that compares the results of the suitability evaluations produced by the first evaluation unit (5100), the second evaluation unit (5200), and the third evaluation unit (5300).

[0173] According to the above, the target selection method of the overlay measurement device of the present invention and the target selection system of the overlay measurement device can select the most similar representative target that can replace all targets formed on a wafer, and the reliability of the selected overlay targets can be improved.

[0174] Accordingly, wafer overlay measurement can be performed using only representative targets formed on the wafer, shortening the wafer overlay measurement time and increasing productivity.

[0175] 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 selecting a plurality of overlay targets formed on a wafer as acquisition targets; (b) a step of performing a suitability evaluation on each of a plurality of evaluation samples formed as different targets among the above acquisition targets, thereby selecting at least one candidate sample from among the plurality of evaluation samples; and (c) a step of selecting targets constituting the above candidate samples as measurement targets to be used in the field map of the overlay measurement recipe; A method for selecting a target of an overlay measuring device, comprising:

2. In paragraph 1, In step (b) above, (b-1) A step of generating a plurality of evaluation samples formed by combinations of different targets among the remaining targets, excluding at least one target among the acquisition targets selected in the previous step; (b-2) a step of performing the suitability evaluation for each of the plurality of evaluation samples; (b-3) a step of selecting a preset number of candidate samples in the order of suitability evaluation among the plurality of evaluation samples; and (b-4) A step of re-selecting the targets constituting the above candidate sample as acquisition targets; Including, A method for selecting a target of an overlay measuring device, wherein steps (b-1) to (b-4) are sequentially repeated.

3. In paragraph 1, Step (c) above, A target selection method for an overlay measurement device, wherein the candidate sample having the best result in the suitability evaluation among the candidate samples selected in the step (b) is selected as the measurement target.

4. In paragraph 1, In step (b) above, A method for selecting a target of an overlay measurement device, which performs the suitability evaluation, which comprises a parameter evaluation calculated as an overlay modeling result value of the plurality of evaluation samples and an overlay measurement evaluation calculated as a difference between the acquisition target and the targets constituting the plurality of evaluation samples.

5. In paragraph 4, In step (b) above, The above parameter evaluation of the above suitability assessment is, Calculating the average and standard deviation of the plurality of element values ​​calculated through the plurality of element values ​​that affect the overlay measurement of the plurality of overlay targets formed on the wafer and the plurality of element values ​​that affect the overlay measurement of the targets constituting the plurality of evaluation samples, The average of the overlay measurement values ​​calculated by setting the remaining element values ​​excluding at least one element value among the above multiple element values ​​to 0 is stored as the first evaluation value, and the standard deviation of the overlay measurement values ​​is stored as the second evaluation value. The above overlay measurement evaluation of the above suitability assessment is, A target selection method of an overlay measurement device, wherein the average of the difference values ​​calculated through the overlay output values ​​produced from the plurality of overlay targets formed on the wafer and the overlay output values ​​produced from the targets constituting the plurality of evaluation samples is stored as a third evaluation value, and the standard deviation of the difference values ​​is stored as a fourth evaluation value.

6. In paragraph 4, In step (b) above, By performing the above parameter evaluation, the order of the multiple evaluation samples is sorted and a set score is assigned according to the order, By performing the above overlay measurement evaluation, the order of the multiple evaluation samples is arranged and a set score is assigned according to the order, A target selection method of an overlay measuring device, wherein the scores of each evaluation sample are added up and at least one evaluation sample among the plurality of evaluation samples is selected based on the added score.

7. In paragraph 1, After step (c) above, (d) a step of comparing the learning wafer used to select the measurement target in steps (a), (b), and (c) with a comparison wafer that did not perform steps (a), (b), and (c), thereby verifying whether the measurement target is a target to be used in the field map of the overlay measurement recipe; A method for selecting a target of an overlay measuring device, comprising:

8. In paragraph 7, Step (d) above, (d-1) A step of performing the suitability evaluation on the measurement target selected in step (c) among the plurality of overlay targets formed on the learning wafer; (d-2) A step of performing the suitability evaluation on a target formed at the same location as the measurement target selected in step (c) among a plurality of overlay targets formed on the comparison wafer; (d-3) a step of performing the suitability evaluation on any target among the plurality of overlay targets formed on the comparison wafer; and (d-4) A step of comparing the results of the suitability assessment produced in the above steps (d-1), (d-2) and (d-3); A method for selecting a target of an overlay measuring device, comprising:

9. An acquisition target selection unit that selects a plurality of overlay targets formed on a wafer as acquisition targets; A candidate sample selection unit that performs a suitability evaluation on each of a plurality of evaluation samples formed as different targets among the above acquisition targets and selects at least one candidate sample from among the plurality of evaluation samples; and A measurement target selection unit for selecting measurement targets to be used in a field map of an overlay measurement recipe from among targets constituting the above candidate samples; A target selection system for an overlay measuring device, comprising:

10. In paragraph 9, The above candidate sample selection unit, An evaluation sample generation unit that generates a plurality of evaluation samples formed by combinations of different targets among the remaining targets, excluding at least one target among the acquisition targets selected in the previous step; An evaluation unit that performs the suitability evaluation for each of the plurality of evaluation samples; A sorting unit that selects a preset number of candidate samples in the order of suitability evaluation from among the plurality of evaluation samples; and A conversion unit that re-selects the targets constituting the above candidate samples as acquisition targets; A target selection system for an overlay measuring device, comprising:

11. In paragraph 9, The above measurement target selection unit, A target selection system for an overlay measurement device, which selects a candidate sample having the best suitability evaluation result among the candidate samples selected by the candidate sample selection unit as the measurement target.

12. In paragraph 9, The above candidate sample selection unit, A target selection system of an overlay measurement device that performs the suitability evaluation, which comprises a parameter evaluation calculated from the overlay modeling result values ​​of the plurality of evaluation samples and an overlay measurement evaluation calculated from the difference between the acquisition target and the targets constituting the plurality of evaluation samples.

13. In paragraph 12, The above parameter evaluation of the above suitability assessment is, Calculating the average and standard deviation of the plurality of element values ​​calculated through the plurality of element values ​​that affect the overlay measurement of the plurality of overlay targets formed on the wafer and the plurality of element values ​​that affect the overlay measurement of the targets constituting the plurality of evaluation samples, The average of the overlay measurement values ​​calculated by setting the remaining element values ​​excluding at least one element value among the above multiple element values ​​to 0 is stored as the first evaluation value, and the standard deviation of the overlay measurement values ​​is stored as the second evaluation value. The above overlay measurement evaluation of the above suitability assessment is, A target selection system of an overlay measurement device, which stores an average of difference values ​​calculated through overlay output values ​​produced from a plurality of overlay targets formed on the wafer and overlay output values ​​produced from targets constituting the plurality of evaluation samples as a third evaluation value, and stores the standard deviation of the difference values ​​as a fourth evaluation value.

14. In paragraph 12, The above candidate sample selection unit, By performing the above parameter evaluation, the order of the multiple evaluation samples is sorted and a set score is assigned according to the order, By performing the above overlay measurement evaluation, the order of the multiple evaluation samples is arranged and a set score is assigned according to the order, A target selection system of an overlay measurement device that adds up the scores of each evaluation sample and selects at least one evaluation sample from among the plurality of evaluation samples based on the summed score.

15. In paragraph 9, A verification unit that compares a learning wafer used to select the measurement target in the acquisition target selection unit, the candidate sample selection unit, and the measurement target selection unit with a comparison wafer for which the measurement target has not been selected, and verifies whether the measurement target is a target to be used in the field map of the overlay measurement recipe; A target selection system for an overlay measuring device, comprising:

16. In paragraph 15, The above verification department, A first evaluation unit that performs the suitability evaluation on the measurement target selected by the measurement target selection unit among a plurality of overlay targets formed on the learning wafer; A second evaluation unit that performs the suitability evaluation on a target formed at the same location as the measurement target selected by the measurement target selection unit among a plurality of overlay targets formed on the comparison wafer; A third evaluation unit that performs the suitability evaluation on any target among the plurality of overlay targets formed on the comparison wafer; and A comparison unit that compares the results of the suitability evaluation produced in the first evaluation unit, the second evaluation unit, and the third evaluation unit; A target selection system for an overlay measuring device, comprising:

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