Method for evaluating liquid displacement state near substrate surface and evaluation substrate

Abstract

To provide a method for evaluating the liquid displacement state near the surface of a substrate and a substrate for evaluation.SOLUTION: An evaluation substrate having a substrate body and at least a pair of electrodes for measuring electrical resistance, at least a portion of which is exposed on the surface of the substrate body, is transported into a substrate processing apparatus, and while the substrate is being cleaned or in standby, a voltage is applied between the at least a pair of electrodes to measure the electrical resistance, and the liquid replacement state near the substrate surface is evaluated on the basis of the measurement data.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating a liquid displacement state in the vicinity of a substrate surface and to an evaluation substrate. [Background technology]

[0002] Currently, chemical mechanical polishing (CMP) equipment is used in the polishing process to flatten substrate surfaces on the nanometer order. After polishing, abrasive particles adhere to the substrate surface in a variety of states. Adhered particles on the substrate surface, which could be a cause of product defects, must be removed reliably, and post-CMP cleaning technology is extremely important.

[0003] The basic cleaning process for removing adhesions on the substrate surface after CMP is as follows: In the first step, physical external forces are applied to the adhesions on the substrate surface using brush cleaning, ultrasonic cleaning, etc., causing them to lift off (float). In the second step, the electrochemical action of the chemical solution is used to remove the floating matter from the substrate by the liquid flow. In the third step, the chemical solution is replaced with pure water, and in the fourth step, the surface is dried.

[0004] In the third stage, the chemical solution and particles in the solution are removed from the substrate by a pure water flow. However, as shown in Figure 12, the liquid flow speed is slow near the substrate surface, making removal difficult. However, residual chemical solution near the substrate surface can lead to corrosion of the metal film. Furthermore, residual chemical solution containing fine particles near the substrate surface can lead to particle residue. Therefore, in the post-CMP cleaning process, liquid replacement near the substrate surface is important from the perspective of suppressing corrosion of the metal film and removing particles.

[0005] Non-Patent Document 1 describes a method in which white water is supplied to the surface of a substrate, and then the supply is switched to pure water only, and the process of liquid replacement is visualized by photographing it from above the substrate with a high-speed camera. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Naoren Handa et al., "Particle Removal Characteristics in Liquid Flow During Wafer Rotation," Proceedings of the Japan Society for Precision Engineering Academic Conference (2017), pp. 7-8 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the visualization images taken with a camera are significantly affected by the upper layer of the liquid film, making it difficult to evaluate the liquid displacement state near the substrate surface.

[0008] The present invention has been made in consideration of the above points, and an object of the present invention is to provide a method for evaluating the liquid displacement state in the vicinity of a substrate surface, and a substrate for evaluation. [Means for solving the problem]

[0009] The method according to the first aspect of the present invention comprises: An evaluation substrate having a substrate body and at least a pair of electrodes for measuring electrical resistance, at least a portion of which is exposed on the surface of the substrate body, is transported into a substrate processing apparatus, and while the substrate is being cleaned or in standby, a voltage is applied between the at least a pair of electrodes to measure the electrical resistance, and the liquid replacement state near the substrate surface is evaluated based on the measurement data.

[0010] According to this embodiment, the electrical resistance of the liquid near the substrate surface (not the upper layer of the liquid film) can be measured by applying a voltage to at least a pair of electrodes at least partially exposed on the surface of the substrate body and measuring the electrical resistance. As described above, when the chemical solution and particles in the liquid on the substrate are discharged by a liquid flow of pure water, the liquid flow speed is slow near the surface of the substrate, making it difficult to discharge. However, by applying a voltage to at least a pair of electrodes at least partially exposed on the surface of the substrate body and measuring the electrical resistance of the liquid near the surface of the substrate, it is possible to detect whether or not the chemical solution containing particles remains near the substrate surface (not the upper layer of the liquid film), and thereby the liquid replacement state near the substrate surface (not the upper layer of the liquid film) can be evaluated.

[0011] A method according to a second aspect of the present invention is the method according to the first aspect, The voltage is an alternating current.

[0012] According to this aspect, when measuring the electrical resistance by applying a voltage to at least one pair of electrodes at least partially exposed on the surface of the substrate body, it is possible to prevent the applied voltage from electrolyzing the liquid near the substrate surface, thereby enabling accurate measurement of the electrical resistance of the liquid near the substrate surface. Furthermore, by changing the frequency of the AC current, it is possible to change the measurement position in the height direction near the substrate surface.

[0013] A method according to a third aspect of the present invention is a method according to the first or second aspect, comprising: Completion of the liquid replacement is determined based on the change over time in the measurement data.

[0014] A method according to a fourth aspect of the present invention is a method according to the first or second aspect, comprising: The measurement data is compared with predetermined normal data, and if the difference exceeds a predetermined range, it is determined to be abnormal.

[0015] A method according to a fifth aspect of the present invention is a method according to the first or second aspect, comprising: The measurement data is compared with predetermined normal data, and if the difference is within a predetermined range, it is determined to be normal.

[0016] A method according to a sixth aspect of the present invention is a method according to any one of the first to fifth aspects, The portion of the electrode exposed on the surface of the substrate body is made of a noble metal.

[0017] According to this aspect, it is possible to prevent the electrode from being corroded by the liquid near the surface of the substrate.

[0018] An evaluation substrate according to a seventh aspect of the present invention is an evaluation substrate used in the method according to any one of the first to sixth aspects, A substrate body, At least one pair of electrodes for measuring electrical resistance, at least a portion of which is exposed on the surface of the substrate body; a signal processing unit that applies a voltage between the at least one pair of electrodes to measure the electrical resistance and stores the measurement data; Equipped with. [Effects of the Invention]

[0019] According to the present invention, the liquid displacement state in the vicinity of the substrate surface can be evaluated. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of an evaluation board according to an embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional view showing a schematic configuration of an evaluation board according to one embodiment. [Figure 3] FIG. 3 is an enlarged view of the area enclosed by the dashed line marked with the symbol A in the evaluation board shown in FIG. [Figure 4] FIG. 4 is an enlarged view of the area enclosed by the dashed line marked with the symbol B in the evaluation board shown in FIG. [Figure 5] FIG. 5 is a block diagram showing a schematic configuration of the signal processing unit. [Figure 6] FIG. 6 is a diagram for explaining how the chemical solution on the substrate is discharged by the flow of pure water. [Figure 7] FIG. 7 is a plan view showing the overall configuration of the substrate processing apparatus. [Figure 8] FIG. 8 is a diagram showing a schematic configuration of an experimental device according to the first example. [Figure 9] FIG. 9 is a graph showing the change over time in electrical resistance measured in the first example. [Figure 10] FIG. 10 is a diagram showing a schematic configuration of an experimental device according to the second example. [Figure 11] FIG. 11 is a graph showing the change over time in electrical resistance measured in the second example. [Figure 12]FIG. 12 is a diagram for explaining the liquid flow velocity when the chemical liquid and particles in the liquid on the substrate are discharged by the flow of pure water. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the drawings used in the following description, parts that can be configured identically will be designated by the same reference numerals, and duplicated descriptions will be omitted.

[0022] (Configuration of evaluation board) Fig. 1 is a plan view showing a schematic configuration of an evaluation board 10 according to one embodiment, and Fig. 2 is a longitudinal cross-sectional view of the same. Fig. 3 is an enlarged view of the area surrounded by the dashed line marked with the symbol A in the evaluation board 10 shown in Fig. 1. Fig. 4 is an enlarged view of the area surrounded by the dashed line marked with the symbol B in the evaluation board 10 shown in Fig. 2.

[0023] As shown in Figures 1 to 4, the evaluation substrate 10 has a substrate main body 11, at least a pair of electrodes 12 for measuring electrical resistance, at least a portion of which is exposed on the surface of the substrate main body 11, and a signal processing unit 13 that applies a voltage between the at least a pair of electrodes 12 to measure the electrical resistance and stores the measurement data.

[0024] Of these, the substrate body 11 is a known substrate used in the manufacture of semiconductor devices, and may be, for example, a silicon substrate, a glass substrate, or a ceramic substrate. A thin film of a common film type, such as a SiN film, may be formed on the surface of the substrate body 11. The size of the substrate body 11 is not particularly limited, and may be, for example, 300 mm in diameter.

[0025] At least one pair of electrodes 12 is provided so that a part of it is exposed on the surface of the substrate body 11. In the illustrated example, one pair of electrodes 12 is provided at the center of the substrate body 11, five pairs of electrodes 12 are provided so as to be aligned at equal intervals (for example, 30 mm intervals) along each of the directions of 0°, 90°, 180°, and 270° as viewed from the center of the substrate body 11, and four pairs of electrodes 12 are provided so as to be aligned at equal intervals (for example, 30 mm intervals) along each of the directions of 45°, 135°, 225°, and 315° as viewed from the center of the substrate body 11. The center-to-center distance between one electrode and the other electrode of a pair of electrodes 12 is, for example, 2 mm, and the area of ​​each electrode is, for example, 1.0 mm. 2 The number, positions, areas, and inter-electrode distance of the at least one pair of electrodes 12 are not limited to the illustrated example, and may be arbitrary. The evaluation substrate 10 may be installed horizontally or vertically. When the evaluation substrate 10 is installed horizontally, the surface of the substrate body 11 from which at least a portion of the at least one pair of electrodes 12 is exposed may be an upward-facing surface (upper surface) or a downward-facing surface (lower surface).

[0026] Referring to Figure 4, each electrode 12 has an internal electrode 121 embedded inside the substrate body 11, a surface electrode 122 arranged on the internal electrode 121 and partially exposed on the surface of the substrate body 11, and an insulating portion 123 arranged to surround the side surfaces of the internal electrode 121 and the surface electrode 122.

[0027] Of these, the surface electrode 122 is made of a conductive material, preferably a noble metal (e.g., platinum). When the surface electrode 122 is made of a noble metal, corrosion of the electrode 12 by the liquid on the surface of the substrate 10 can be suppressed. The material of the internal electrode 121 is not particularly limited as long as it is a conductive material, and may be, for example, copper or a noble metal such as platinum. The insulating portion 123 is made of a general insulating material such as resin.

[0028] An example of a method for fabricating an electrode 12 having such a configuration on the substrate body 11 will be described below. First, a through hole is formed in the substrate body 11 using a laser. Next, the periphery of the internal electrode 121 and the surface electrode 122 is covered with an insulator to form an insulating portion 123, which is then inserted into the through hole. In this way, the electrode 12 can be fabricated on the substrate body 11.

[0029] Another example of a method for forming an electrode 12 on the substrate body 11 will be described. First, a resist is applied to the surface of the substrate body 11, and then only the resist in the area where the electrode is to be formed is exposed using an exposure device, and the resist in that area is removed to form a mask resist. Next, the area of ​​the surface film of the substrate body 11 where the electrode is to be formed (the area where the resist has been removed) is removed by etching, and the area of ​​the substrate body 11 where the electrode is to be formed (the area where the resist and surface film have been removed) is also removed by etching to form a TSV (Through Silicon Via). Next, an insulating film is formed on the inner wall of the TSV to form an insulating portion 123, and then a barrier metal is formed. Next, Cu plating is performed on the inner wall of the TSV, and the Cu on the surface of the substrate body 11 is removed by CMP processing to form an internal electrode 121. Next, platinum is formed on the internal electrode 121 by sputtering to form a surface electrode 122. Alternatively, gold plating is performed on the inner wall of the TSV, and then the gold on the surface of the substrate body 11 is removed by CMP processing to form the internal electrode 121 and the surface electrode 122. Then, the mask resist is removed by wet cleaning. In this way, the electrodes 12 can be formed on the substrate body 11.

[0030] Next, a description will be given of the configuration of the signal processing unit 13. FIG.

[0031] As shown in FIG. 5, the signal processing unit 13 includes a single-board computer 131, a battery 132, and a storage 133.

[0032] Of these, the single-board computer 131 is electrically connected to each of at least a pair of electrodes 12 for measuring electrical resistance, at least a portion of which is exposed on the surface of the substrate body 11, and performs a process of applying a voltage between the at least a pair of electrodes 12 to measure the electrical resistance and storing the measurement data in storage 133.

[0033] 6, the single-board computer 131 applies a voltage to at least one pair of electrodes 12, at least a portion of which is exposed on the surface of the substrate body 11, and measures the electrical resistance, thereby measuring the electrical resistance of the liquid near the surface of the substrate 10 (rather than the upper layer of the liquid film). As shown in Fig. 6, when the chemical solution and submerged particles 22 on the substrate 10 are discharged by the liquid flow of pure water 21, the liquid flow speed is slow near the surface of the substrate 10, making it difficult to discharge the liquid. However, by applying a voltage to at least one pair of electrodes 12, at least a portion of which is exposed on the surface of the substrate body 11, and measuring the electrical resistance of the liquid near the surface of the substrate 10, it is possible to detect whether or not the chemical solution containing fine particles remains near the surface of the substrate 10 (rather than the upper layer of the liquid film), and thereby evaluate the liquid replacement state near the surface of the substrate 10 (rather than the upper layer of the liquid film).

[0034] The voltage applied between at least one pair of electrodes 12 by the single-board computer 131 may be either DC or AC. In the case of AC, the voltage applied between at least one pair of electrodes 12 can prevent the liquid near the surface of the substrate 10 from being electrolyzed, thereby enabling accurate measurement of the electrical resistance of the liquid near the surface of the substrate 10. Furthermore, by changing the frequency of the AC voltage applied between at least one pair of electrodes 12, it becomes possible to change the measurement position of the electrical resistance in the height direction near the surface of the substrate 10.

[0035] The battery 132 supplies power to drive the single-board computer 131. As the battery 132, for example, a lithium-ion battery can be used.

[0036] The storage 133 records and holds the measurement data (electrical resistance values) measured by the single-board computer 131. As the storage 133, for example, a non-volatile data storage such as a hard disk or a flash memory can be used.

[0037] (Configuration of substrate processing apparatus) Next, an example of a substrate processing apparatus 30 to which the evaluation substrate 10 having such a configuration is transported when the liquid replacement state near the substrate surface is evaluated using the evaluation substrate 10 will be described. Figure 7 is a plan view showing the overall configuration of a substrate processing apparatus (also called a polishing apparatus) 30 according to one embodiment.

[0038] As shown in FIG. 7, the substrate processing apparatus 30 has a substantially rectangular housing 31 and a load port 32 on which a substrate cassette (not shown) for stocking a plurality of wafers W is placed. The load port 32 is disposed adjacent to the housing 31. An open cassette, a Standard Manufacturing Interface (SMIF) pod, or a Front Opening Unified Pod (FOUP) can be mounted on the load port 32. The SMIF pod and the FOUP are hermetically sealed containers that house a substrate cassette and are covered with a partition wall, thereby maintaining an environment independent from the external space. The wafers W may be, for example, semiconductor wafers.

[0039] The housing 31 accommodates a plurality of (four in the embodiment shown in FIG. 7) polishing units 33a to 33d, a first cleaning unit 35 and a second cleaning unit 36 ​​that clean the polished wafer W, and a drying unit 37 that dries the cleaned wafer W. The polishing units 33a to 33d are arranged along the longitudinal direction of the housing 31, and the cleaning units 35, 36 and the drying unit 37 are also arranged along the longitudinal direction of the housing 31.

[0040] A first transfer robot 32 is disposed in an area surrounded by the load port 32, the polishing unit 33a located on the load port 32 side, and the drying unit 37. A transfer unit 34 is disposed parallel to the longitudinal direction of the housing 31 between the area where the polishing units 33a to 33d are arranged and the area where the cleaning units 35 and 36 and the drying unit 37 are arranged. The first transfer robot 32 receives an unpolished wafer W from the load port 32 and delivers it to the transfer unit 34, and receives from the drying unit 37 a wafer W that has been taken out of the drying unit 37 and has been dried.

[0041] A second transfer robot 38 is disposed between the first cleaning unit 35 and the second cleaning unit 36, and transfers the wafer W between the first cleaning unit 35 and the second cleaning unit 36. In addition, a third transfer robot 39 is disposed between the second cleaning unit 36 ​​and the drying unit 37, and transfers the wafer W between the second cleaning unit 36 ​​and the drying unit 37.

[0042] 7, a roll cleaning device is used as the first cleaning unit 35, which brings a horizontally extending roll cleaning member into contact with the surface of the wafer W in the presence of a cleaning liquid and rotates the roll cleaning member to scrub the surface of the wafer W, and a pencil cleaning device is used as the second cleaning unit 36, which brings a vertically extending cylindrical pencil cleaning member into contact with the surface of the wafer W in the presence of a cleaning liquid and moves the pencil cleaning member in one direction parallel to the surface of the wafer W while rotating, to scrub the surface of the wafer W. Furthermore, a spin dryer is used as the drying unit 37, which sprays isopropyl alcohol (IPA) vapor toward the rotating wafer W from a spray nozzle that moves in one direction parallel to the surface of the wafer W to dry the wafer W, and further rotates the wafer W at high speed to dry the wafer W by centrifugal force.

[0043] In this example, a roll cleaning device is used as the first cleaning unit 35, but a pencil cleaning device similar to the second cleaning unit 36 ​​may be used as the first cleaning unit 35, or a buffing cleaning device may be used that brings a buffing / polishing member having a rotation axis extending vertically into contact with the surface of the wafer W in the presence of a cleaning liquid and moves the buffing / polishing member in one direction parallel to the surface of the wafer W while rotating, thereby scrubbing, cleaning, and polishing the surface of the wafer W, or a two-fluid jet cleaning device that cleans the surface of the wafer W with a two-fluid jet may be used. Also, in this example, a pencil cleaning device is used as the second cleaning unit 36, but a roll cleaning device similar to the first cleaning unit 35, a buffing / polishing device, or a two-fluid jet cleaning device may be used as the second cleaning unit 36.

[0044] The cleaning liquid includes a rinse liquid such as deionized water (DIW) and chemical liquids such as ammonia hydrogen peroxide (SC1), hydrochloric acid hydrogen peroxide (SC2), sulfuric acid hydrogen peroxide (SPM), sulfuric acid water, and hydrofluoric acid.

[0045] In such a substrate processing apparatus 30, the wafer W before polishing is removed from the load port 32 by the first transfer robot 32 and transferred to the polishing units 33a and 33b via the transfer unit 34 for polishing. Next, the polished wafer W is transferred to the first cleaning unit 35 via the transfer unit 34 for cleaning, then transferred to the second cleaning unit 36 ​​via the second transfer robot 38 for cleaning, and finally transferred to the drying unit 37 via the third transfer robot 39 for drying. Thereafter, the dried wafer W is removed from the drying unit 37 by the first transfer robot 32 and returned to the load port 32.

[0046] (Method for evaluating the liquid displacement state near the substrate surface) Next, a method for evaluating the liquid replacement state in the vicinity of the substrate surface using the evaluation substrate 10 in the substrate processing apparatus 30 described above will be described.

[0047] In one embodiment, the evaluation substrate 10 having the above-described configuration is transferred into the substrate processing apparatus 30 instead of the wafer W, for example, when the substrate processing apparatus 30 is started up or when an abnormality is detected during substrate processing.

[0048] Then, in the substrate processing apparatus 30, the evaluation substrate 10 is transferred from the load port 32 to the polishing units 33a and 33b, similar to the wafer W, and then transferred to the first cleaning unit 35 and the second cleaning unit 36 ​​for cleaning. Here, while the evaluation substrate 10 is being cleaned in the first cleaning unit 35 and the second cleaning unit 36 ​​or is on standby (at this time, the evaluation substrate 10 may be installed horizontally or vertically), the single-board computer 131 of the signal processing unit 13 applies a voltage (for example, an AC voltage) between at least one pair of electrodes 12, at least a portion of which is exposed on the surface of the substrate body 11, to measure the electrical resistance of the liquid near the surface of the substrate 10 and store the measurement data in the storage 133.

[0049] Then, the evaluation substrate 10 after cleaning is transported to the drying unit 37 for drying processing, and then returned to the load port 32 and removed from the substrate processing apparatus 10. The measurement data is read out from the storage 133, and the liquid replacement state near the surface of the substrate 10 during cleaning or standby is evaluated based on the measurement data.

[0050] As a first example of evaluation of the liquid replacement state, completion of the liquid replacement near the surface of the substrate 10 may be determined based on the change over time of the measurement data. Specifically, for example, when a conductive chemical liquid is replaced with pure water, the electrical resistance value of the liquid increases. Therefore, when the electrical resistance (measurement data) of the liquid near the surface of the substrate 10 reaches a predetermined reference value (for example, 10 7 When the resistance exceeds the predetermined resistance value (Ω, etc.), it may be determined that the liquid replacement is complete at that timing.

[0051] As a second example of evaluating the liquid replacement state, the measurement data may be compared with predetermined normal data, and if the difference exceeds a predetermined range, an abnormality may be determined. Specifically, for example, during substrate processing in the substrate processing apparatus 30 (normal operation), an evaluation substrate 10 may be transferred into the substrate processing apparatus 30 instead of a wafer W, the electrical resistance of the liquid near the surface of the substrate 10 may be measured during cleaning or standby, and the measurement data may be stored in advance as normal operation data. Then, when an abnormality is detected during substrate processing in the substrate processing apparatus 30, the evaluation substrate 10 may be transferred into the substrate processing apparatus 30 instead of a wafer W, the electrical resistance of the liquid near the surface of the substrate 10 may be measured during cleaning or standby, and the measurement data may be compared with the previously stored normal operation data. If the difference exceeds a predetermined range, it may be determined that an abnormality has occurred (that the abnormality detection was correct).

[0052] As a third example of evaluating the liquid replacement state, the measurement data may be compared with predetermined normal data, and if the difference is within a predetermined range, the state may be determined to be normal. Specifically, for example, during substrate processing (normal operation) before the substrate processing apparatus 30 is delivered to a customer, an evaluation substrate 10 may be transferred into the substrate processing apparatus 30 instead of a wafer W, the electrical resistance of the liquid near the surface of the substrate 10 may be measured during cleaning or standby, and the measurement data may be stored in advance as normal data. Then, when the substrate processing apparatus 30 is delivered to a customer and set up, the evaluation substrate 10 may be transferred into the substrate processing apparatus 30 instead of a wafer W, the electrical resistance of the liquid near the surface of the substrate 10 may be measured during cleaning or standby, and the measurement data may be compared with the previously stored normal data, and if the difference is within a predetermined range, the state may be determined to be normal (normal start-up).

[0053] According to the present embodiment as described above, the electrical resistance of the liquid near the surface of substrate 10 (rather than the upper layer of the liquid film) can be measured by applying a voltage to at least one pair of electrodes 12 at least partially exposed on the surface of substrate body 11 and measuring the electrical resistance. When the chemical solution and particles in the liquid on the substrate are discharged using a liquid flow of pure water, the liquid flow speed is slow near the surface of the substrate, making it difficult to discharge the liquid. However, by applying a voltage to at least one pair of electrodes 12 at least partially exposed on the surface of substrate body 11 and measuring the electrical resistance of the liquid near the surface of substrate 10, it is possible to detect whether or not the chemical solution containing particles remains near the surface of substrate 10 (rather than the upper layer of the liquid film), and thereby the liquid replacement state near the surface of substrate 10 (rather than the upper layer of the liquid film) can be evaluated.

[0054] Furthermore, according to this embodiment, by measuring the electrical resistance by applying an AC voltage to at least one pair of electrodes 12 at least partially exposed on the surface of substrate body 11, it is possible to prevent the liquid near the substrate surface from being electrolyzed by the applied voltage, thereby enabling accurate measurement of the electrical resistance of the liquid near the substrate surface. Furthermore, by changing the frequency of the AC voltage, it is possible to change the measurement position in the height direction near the surface of substrate 10.

[0055] Furthermore, according to this embodiment, the portion of electrode 12 exposed on the surface of substrate body 11 (surface electrode 122) is made of a precious metal, so that corrosion of electrode 12 by liquid near the surface of substrate 10 can be suppressed.

[0056] Next, a specific example according to this embodiment will be described.

[0057] (First Example) FIG. 8 is a diagram showing the schematic configuration of an experimental apparatus according to the first embodiment. As shown in FIG. 8, in the first embodiment, a pair of platinum electrodes (each with a diameter of 0.5 mm and a center-to-center distance between the electrodes of 2 mm) was embedded in a 300 mm Φ acrylic disk so that at least a portion of the pair of platinum electrodes was exposed on the surface (top surface) of the acrylic disk. The acrylic disk with the embedded platinum electrodes was then fixed onto an acrylic plate, which was then fixed onto an aluminum plate via pillars. Next, a single-board computer was electrically connected to the pair of platinum electrodes from below the acrylic plate, and the single-board computer was placed on the aluminum plate. In this way, an evaluation board 10 was fabricated, which included a board main body 11 (acrylic disk), a pair of electrodes 12 (platinum electrodes), and a signal processing unit 13 (single-board computer).

[0058] As an example, the fabricated evaluation substrate 10 was rotated around a rotation axis passing through the center of the substrate body 11 (acrylic disc), and a conductive chemical solution (0.5 wt% Na2CO3 aqueous solution) was supplied from a nozzle positioned on the rotation axis toward the center of the surface (top surface) of the substrate body 11 (acrylic disc). After 10 seconds, the supply of the chemical solution was stopped and the supply of pure water was started. While the liquid was being supplied to the substrate surface, an AC voltage was applied from a signal processing unit 13 (single-board computer) between a pair of electrodes 12 (platinum electrodes) to measure electrical resistance. Here, the rotation speed N of the evaluation substrate 10 was 100 rpm, the flow rate Q of the liquid supplied to the surface of the substrate 10 was 1.5 L / min, and the distance r from the center of the substrate body 11 (acrylic disc) to the pair of electrodes 12 (platinum electrodes) was 50 mm.

[0059] As a comparative example, the fabricated evaluation substrate 10 was rotated around a rotation axis passing through the center of the substrate body 11 (acrylic disc), and pure water was supplied from a nozzle positioned on the rotation axis toward the center of the surface (top surface) of the substrate body 11 (acrylic disc) from the beginning. During the liquid supply, an AC voltage was applied from the signal processing unit 13 (single-board computer) between the pair of electrodes 12 (platinum electrodes) to measure the electrical resistance. Here, the experiment was conducted under the same conditions as in the example, except for the liquid supplied to the surface of the substrate body 11 (acrylic disc).

[0060] 9 is a graph showing the change over time in the electrical resistance measured in each of the example and the comparative example. As shown in Fig. 9, in the example, while the chemical solution was being supplied to the surface of the substrate body 11 (acrylic disc) (up to 10 seconds after the start of the liquid supply), the electrical resistance was 0 Ω. However, when the chemical solution was switched to pure water (10 seconds after the start of the liquid supply), the electrical resistance increased to about 3 × 10 Ω 2 to 3 seconds after the switching. 7 On the other hand, in the comparative example in which pure water was supplied to the surface of the substrate body 11 (acrylic disc) from the beginning, the measured electrical resistance was about 3×10 7 There was no change in Ω. From these results, it was confirmed that by applying a voltage to at least one pair of electrodes 12, at least a portion of which is exposed on the surface of the substrate body 11, and measuring the electrical resistance of the liquid near the substrate surface, it is possible to detect whether or not the chemical liquid remains near the substrate surface (rather than in the upper layer of the liquid film), and that this makes it possible to evaluate the liquid replacement state near the substrate surface (rather than in the upper layer of the liquid film) based on the measurement data. Note that, from the relationship between the height from the substrate surface and the liquid replacement rate, it can be estimated that the electrical resistance measurement here was taken at a height of approximately 2 μm.

[0061] (Second Example) FIG. 10 is a diagram showing the schematic configuration of an experimental apparatus according to the second example. As shown in FIG. 10, in the second example, a pair of platinum electrodes was embedded in a 300 mm diameter wafer so that at least a portion of the pair of platinum electrodes was exposed on the surface (bottom) of the wafer (SiN film). The wafer with the embedded platinum electrodes was then fixed under an acrylic plate, which was then fixed via pillars under an aluminum plate (not shown). Next, a single-board computer (not shown) was electrically connected to the pair of platinum electrodes from above the acrylic plate, and the single-board computer was placed on the aluminum plate. In this manner, an evaluation substrate 10 was fabricated, which included a substrate main body 11 (wafer), a pair of electrodes 12 (platinum electrodes), and a signal processing unit 13 (single-board computer).

[0062] In Example 1 (Nozzle A), the fabricated evaluation substrate 10 was rotated around a rotation axis passing through the center of the substrate body 11 (wafer). A conductive chemical solution (NaCO aqueous solution) was then supplied from a nozzle positioned on the rotation axis toward the center of the surface (underside) of the substrate body 11 (wafer). After 10 seconds, the supply of the chemical solution was stopped, and pure water was supplied from a nozzle A (one single-tube nozzle and one spray nozzle) positioned away from the rotation axis toward the center of the surface (underside) of the substrate body 11 (wafer). While the liquid was being supplied to the substrate surface, an AC voltage was applied from a signal processing unit 13 (single-board computer) between a pair of electrodes 12 (platinum electrodes) to measure electrical resistance. Here, the rotation speed N of the evaluation substrate 10 was 150 rpm, the liquid supply flow rate Q to the surface of the substrate 10 was 1.0 L / min, and the distance r from the center of the substrate body 11 (wafer) to the pair of electrodes 12 (platinum electrodes) was 100 mm.

[0063] In Example 2 (Nozzle B), the fabricated evaluation substrate 10 was rotated around a rotation axis passing through the center of the substrate body 11 (acrylic disc), and a conductive chemical solution (Na2CO3 aqueous solution) was supplied from a nozzle positioned on the rotation axis toward the center of the surface (underside) of the substrate body 11 (wafer). After 10 seconds, the supply of the chemical solution was stopped, and pure water was supplied from Nozzle B (two single-tube nozzles) positioned away from the rotation axis toward the center of the surface (underside) of the substrate body 11 (wafer). Then, while the liquid was being supplied to the substrate surface, an AC voltage was applied from the signal processing unit 13 (single-board computer) between a pair of electrodes 12 (platinum electrodes) to measure electrical resistance. Here, the experiment was conducted under the same conditions as Example 1, except for the type of nozzle (Nozzle A and Nozzle B) that supplied the pure water.

[0064] 11 is a graph showing the change over time in electrical resistance measured in each of Examples 1 and 2. As shown in FIG. 11, in Example 1, when the chemical solution was switched to pure water (10 seconds after the start of liquid supply), the electrical resistance increased to 40×10 7 It was confirmed that the electrical resistance instantaneously increased to more than Ω. On the other hand, in Example 2, when the chemical solution was switched to pure water (10 seconds after the start of liquid supply), the electrical resistance began to increase approximately 5 seconds after the switching, but the rate of increase was confirmed to be slower than in Example 1. From these results, it can be seen that nozzle A has a higher rate of increase in electrical resistance and therefore a better liquid replacement efficiency than nozzle B. Therefore, by applying a voltage to at least one pair of electrodes 12 at least partially exposed on the surface of substrate body 11, measuring the electrical resistance of the liquid near the substrate surface, and analyzing the measurement data, it is possible to evaluate the liquid replacement efficiency according to nozzle type.

[0065] Although the embodiments and modifications of the present invention have been described above by way of example, the scope of the present invention is not limited to these, and modifications and variations can be made according to the purpose within the scope of the claims. Furthermore, the embodiments and modifications can be combined as appropriate within the scope of the processing content. [Explanation of symbols]

[0066] 10 Evaluation board 11 Board body 12 electrodes 121 Internal electrode 122 Surface electrode 123 Insulation 13 Signal Processing Section 131 Single Board Computer 132 Battery 133 Storage 21 Pure water 22 Chemical Solution

Claims

1. A method for evaluating a liquid displacement state near the substrate surface, comprising: transporting an evaluation substrate, which includes a substrate body and at least a pair of electrodes for measuring electrical resistance, at least a portion of which is exposed on the surface of the substrate body, into a substrate processing apparatus; applying a voltage between the at least a pair of electrodes to measure the electrical resistance while the substrate is being cleaned or while the substrate is in standby; and evaluating the liquid displacement state near the substrate surface based on the measurement data.

2. The method of claim 1 , wherein the voltage is an alternating current.

3. The method according to claim 1 or 2, wherein completion of liquid replacement is determined based on a change in the measurement data over time.

4. 3. The method according to claim 1, wherein the measurement data is compared with predetermined normal data, and if the difference exceeds a predetermined range, the measurement data is determined to be abnormal.

5. 3. The method according to claim 1, wherein the measurement data is compared with predetermined normal data, and the measurement data is determined to be normal if the difference is within a predetermined range.

6. 3. The method according to claim 1, wherein the portion of the electrode exposed on the surface of the substrate body is made of a noble metal.

7. An evaluation substrate used in the method according to claim 1 or 2, A substrate body, At least one pair of electrodes for measuring electrical resistance, at least a portion of which is exposed on the surface of the substrate body; a signal processing unit that applies a voltage between the at least one pair of electrodes to measure the electrical resistance and stores the measurement data; An evaluation board comprising:

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