Electrical property measuring apparatus, measuring substrate and electrical property measuring method

Abstract

The electrical characteristic measuring device of the present invention includes: a measuring substrate (2) having a pair of electrodes formed on its upper surface; a substrate holding part (11) holding the measuring substrate (2); a substrate rotating part rotating the measuring substrate (2) about an axis perpendicular to the measuring substrate (2); a liquid supply part supplying a specified liquid to the measuring substrate (2); a measuring circuit fixed to the substrate holding part (11), rotating together with the measuring substrate (2), electrically connected to the pair of electrodes, and obtaining a value representing the electrical characteristics between the pair of electrodes; and a control part controlling the substrate rotating part, the liquid supply part, and the measuring circuit to obtain a value representing the electrical characteristics between the pair of electrodes during or after the period when the measuring substrate (2) is rotated and a specified liquid is supplied to the measuring substrate (2).

Description

[Technical Field]

[0001] This invention relates to a technique for measuring the electrical properties of a substrate surface. [Reference to related applications] This application claims the benefit of priority to Japanese Patent Application JP2024-148477, filed on August 30, 2024, all disclosures of which are incorporated herein by reference. [Previous Technology]

[0002] Since the beginning of the industry, various proposals have been put forward to measure the processing conditions of semiconductor substrates. For example, Japanese Patent Publication No. 2007-536726 proposed to install sensors and transmitters on the substrate to measure the temperature, pressure, force, strain, flow rate, chemical concentration of gas, or ion current density or ion current energy in structures such as parallel plates during processing.

[0003] On the other hand, Japanese Patent Application Publication No. 9-292358 disclosed the following technology: a sensing part is formed on one side of a semiconductor substrate, a liquid sample containing microparticles for electrophoresis is disposed on the sensing part, and a detection light is emitted toward the other side and a signal is extracted, thereby measuring the zeta potential.

[0004] Furthermore, the technology of supplying liquid to a rotating substrate for processing is used in various processes, but it is impossible to measure the surface condition of the substrate in real time, thus making it difficult to conduct proper research and development. [Summary of the Invention]

[0005] The purpose of this invention is to measure the surface condition of a rotating substrate that has been supplied with liquid in real time.

[0006] The electrical characteristic measuring device of the present invention (Sample 1) includes: a measuring substrate having a pair of electrodes formed on its upper surface; a substrate holding portion holding the measuring substrate; a substrate rotating portion rotating the measuring substrate about an axis perpendicular to the measuring substrate; a liquid supply portion supplying a predetermined liquid to the measuring substrate; a measuring circuit fixed to the substrate holding portion, rotating together with the measuring substrate, electrically connected to the pair of electrodes, and obtaining a value representing the electrical characteristics between the pair of electrodes; and a control portion controlling the substrate rotating portion, the liquid supply portion, and the measuring circuit to obtain the value representing the electrical characteristics between the pair of electrodes during or after the supply of the predetermined liquid to the measuring substrate while rotating the measuring substrate.

[0007] According to the present invention, the surface condition of a substrate that is rotated and supplied with liquid can be measured in real time.

[0008] The present invention, sample 2, is an electrical characteristic measuring device as in sample 1, further comprising a wireless communication unit; and transmitting from the aforementioned wireless communication unit a value representing the aforementioned electrical characteristics between the aforementioned pair of electrodes.

[0009] The present invention, sample 3, is an electrical characteristic measuring device like sample 1 (or sample 1 or 2), wherein the aforementioned measuring substrate and the aforementioned measuring circuit can be separated; the aforementioned substrate holding part can hold the substrate of the object to be treated with the processing liquid and replace the aforementioned measuring substrate.

[0010] The state sample 4 of the present invention is an electrical characteristic measuring device like state sample 1 (or any one of state sample 1 to 3), and further includes a calculation unit, which calculates the charge on the aforementioned measuring substrate at the position of the aforementioned pair of electrodes based on the time change of the value representing the aforementioned electrical characteristic obtained by the aforementioned measuring circuit.

[0011] The present invention, in form 5, is an electrical characteristic measuring device as described in form 4, wherein, while the measuring substrate is rotated and pure water is supplied from the liquid supply unit to the measuring substrate, the time change representing the impedance value is obtained by the measuring circuit and used as a value representing the electrical characteristic; and the calculation unit performs the following fitting by comparing the time change representing the impedance value obtained under a non-energized state with the time change representing the impedance value obtained by the measuring circuit:

[0012] [Number 1],

[0013] The values ​​of α, τ, and δ are obtained, where t is the supply time of pure water, α is a proportionality constant, τ is a time constant, and δ is the delay time.

[0014] The present invention, the sample 6, is an electrical characteristic measuring device like sample 1 (or at least any one of sample 1 to 5), wherein a plurality of pairs of electrodes including the aforementioned pair of electrodes are provided on the aforementioned measuring substrate; and the aforementioned plurality of pairs of electrodes are arranged at different positions in the radial direction of the aforementioned measuring substrate.

[0015] The present invention, sample 7, is an electrical characteristic measuring device of any of samples 1 to 6, wherein the aforementioned substrate rotating part includes a disk-shaped rotating base facing the lower surface of the aforementioned measuring substrate; and the aforementioned measuring circuit is located inside the aforementioned rotating base.

[0016] The measuring substrate of the present invention is used to evaluate the charge on the upper surface of a liquid supplied while rotating, and includes: a plurality of pairs of electrodes disposed on the upper surface; a plurality of wires extending from the plurality of pairs of electrodes to the outer edge of the upper surface; and a plurality of connection points, which are the ends of the plurality of wires in the outer edge for electrical connection with the outside.

[0017] The method for measuring the electrical characteristics of the present invention sample 9 includes the following steps: a) holding a measuring substrate on which a pair of electrodes are formed on its upper surface, and rotating the measuring substrate about an axis perpendicular to the measuring substrate; b) supplying a specified liquid onto the measuring substrate in parallel with step a); c) obtaining a value representing the electrical characteristics between the pair of electrodes in parallel with step b) or after step b).

[0018] The present invention, sample 10, is an electrical characteristic measurement method of sample 9, wherein, prior to step a) before step b), the method further includes the following step: d) supplying electrolyte to the aforementioned measurement substrate.

[0019] The above-mentioned objects, other objects, features, features and advantages will become clear from the following detailed description of the invention with reference to the accompanying drawings.

Implementation Method

[0021] FIG1 is a front view showing a schematic configuration of an electrical characteristic measuring apparatus 1 according to one embodiment of the present invention. A portion of the electrical characteristic measuring apparatus 1 is shown in longitudinal section in FIG1. ​​The electrical characteristic measuring apparatus 1 is a modification of a general monolithic substrate processing apparatus, further holding the substrate 2 (hereinafter referred to as "measuring substrate" or "substrate") for measurement. The electrical characteristic measuring apparatus 1 includes: a substrate holding part 11, a substrate rotating part 12, a cup part 13, a plurality of liquid supply parts 14, and a housing 15. The substrate holding part 11, the substrate rotating part 12, the cup part 13, and the liquid supply parts 14 are housed in the internal space of the housing 15. An airflow forming part 151 is provided on the top cover of the housing 15, which supplies gas to the internal space to form a downward airflow (so-called downflow). As the airflow forming part 151, for example, an FFU (fan filter unit) is used. The electrical characteristic measuring device 1 further includes a control unit (not shown in the figure), which controls the substrate holding unit 11, the substrate rotating unit 12, the cup unit 13, and the liquid supply unit 14.

[0022] The substrate holding part 11 holds the measuring substrate 2 in a horizontal position. The substrate holding part 11 uses a clamping pin 111 to hold the outer periphery of the measuring substrate 2.

[0023] The substrate rotating part 12 is disposed below the substrate holding part 11. The substrate rotating part 12 rotates the measuring substrate 2 together with the substrate holding part 11 around a rotation axis J1 facing the vertical direction. This allows the measuring substrate 2 to rotate around an axis perpendicular to the measuring substrate 2. The substrate rotating part 12 includes a shaft 121 and a motor 122. The shaft 121 is a generally cylindrical or generally cylindrical member centered on the rotation axis J1. The shaft 121 extends vertically and is connected to the center of the lower surface of the substrate holding part 11. The motor 122 is an electric rotary motor that rotates the shaft 121. Alternatively, the substrate rotating part 12 may be a motor with other structures (e.g., a hollow motor).

[0024] The liquid supply unit 14 is a supply nozzle that supplies a specified liquid to the surface of the measurement substrate 2 held on the substrate holding unit 11. The liquid supply unit 14 can be understood as including a configuration that guides the liquid to the supply nozzle. The liquid contains SPM (Sulfuric acid hydrogen peroxide mixture), SC1 (ammonia-hydrogen peroxide mixture), SC2 (hydrochloric acid-hydrogen peroxide mixture), diluted hydrogen peroxide, and DIW (deionized water) as a rinsing solution. In the following description, these liquids are sometimes referred to as "processing liquids". In Figure 1, two nozzles are shown as the liquid supply unit 14, spraying liquid from above the measurement substrate 2 onto the upper surface of the measurement substrate 2; however, other nozzles may be further provided. The nozzle outlet of each liquid supply unit 14 can be moved between a position above the measurement substrate 2 and a position offset from above the measurement substrate 2 by a nozzle moving mechanism (not shown).

[0025] The cup portion 13 has an annular cup centered on the rotation axis J1, which receives liquids such as processing liquids that are scattered from the rotating measuring substrate 2. At the bottom of the cup portion 13, a drain port (not shown) is provided to discharge the processing liquids collected by the cups to the outside of the housing 15. In practice, a plurality of cups exist in a concentric circle, and each cup can move up and down. Each cup receives a specific liquid scattered from the measuring substrate 2.

[0026] FIG2 is a top view of the measuring substrate 2. The measuring substrate 2 is formed on a semiconductor substrate with a diameter of 300 mm, on which electrodes, wiring, etc. are formed. As shown in FIG2, a plurality of electrode pairs 21, 22, 23 are formed on the upper surface of the measuring substrate 2. Each electrode pair is a pair of electrodes. A plurality of wirings 24 extending from the plurality of electrode pairs to the outer edge of the upper surface are provided on the upper surface. A plurality of connection points 25, 26 are also provided on the upper surface. Connection points 25, 26 are also the ends of the plurality of wirings 24 in the outer edge and are used for electrical connection with the outside. When the wirings 24 and the connection points 25, 26 are understood as different components, the wirings 24 connect the plurality of electrode pairs 21, 22, 23 and the plurality of connection points 25, 26.

[0027] In electrode pair 21, rectangular electrodes are arranged close together. For example, the cell constant is 550,000 cm⁻¹, the electrode length is 10 mm, and the distance between electrodes is 1 mm. In the example of Figure 2, three electrode pairs 21 are arranged radially in a straight line above the top of Figure 2. In electrode pair 22, comb-shaped electrodes are arranged close to each other in such a way that one comb tooth is positioned between another comb tooth. For example, the cell constant is 300 cm⁻¹, the electrode length is 740 mm, the distance between electrodes is 40 μm, and the number of comb teeth on each electrode is 63. In the example of Figure 2, seven electrode pairs 22 are arranged radially in a straight line from the center of Figure 2 to the upper right, and two electrode pairs 22 are arranged from the center of Figure 2 to the lower right.

[0028] In the electrode pair 23, the comb-shaped electrodes are arranged close to each other in such a way that they are positioned between the teeth of one comb and the teeth of another. For example, the cell constant is 300 cm⁻¹, the electrode length is 185 mm, the distance between the electrodes is 10 μm, and the number of teeth of each electrode is 63. In the example of Figure 2, eight electrode pairs 23 are arranged in a radial straight line from the center of Figure 2 to the right, and two electrode pairs 23 are arranged on the lower side of Figure 2.

[0029] Thus, in the measuring substrate 2, a plurality of electrodes are arranged at different positions in the radial direction of the measuring substrate 2, and the electrical characteristics at various positions in the radial direction of the measuring substrate 2 can be obtained.

[0030] Connection point 25 is a solder pad used for electrical connection with external wiring using silver paste. Connection point 26 is a solder pad used to connect the connecting part 27, which is indicated by a two-point chain line, using silver paste. The wiring 24 is electrically connected to the external wiring through the connecting part 27.

[0031] Electrode pairs 21, 22, 23 and wiring 24 are formed, for example, using gold (Au) with a thickness of 180 nm. Connection points 25, 26 have, for example, a structure in which a nickel (Ni) layer with a thickness of 250 nm is superimposed on a titanium (Ti) layer with a thickness of 30 nm. Three electrode pairs 21, 22, and 23 are provided on the measurement substrate 2 for various measurement evaluations. The electrode pairs are planar electrodes to avoid obstructing the flow of liquids on the measurement substrate 2, as described later.

[0032] Figure 3 is a longitudinal sectional view of the substrate holding section 11 and the measuring substrate 2. Parallel diagonal lines indicating the cross-section are omitted in some sections. The measuring substrate 2 and the substrate holding section 11 are connected by a wiring 119. The wiring 119 is, for example, a flat cable. One end of the wiring 119 is connected to a selected connection point 25 or connection point 26 on the measuring substrate 2 via silver paste or a connecting part 27. This electrically connects the wiring 119 to the wiring 24 on the measuring substrate 2. That is, a predetermined electrode pair is connected to the wiring 119.

[0033] The measuring substrate 2 in Figure 2 is only an example. In the example of Figure 2, wiring 119 is connected to a portion of the connection points 25 and 26. However, depending on the layout of the electrode pairs, wiring, and connection points on the measuring substrate 2, the number of wires in wiring 119 can be set to be the same as the number of connection points, and wiring 119 can be connected to all connection points. When wiring 119 and connection point 25 are connected with silver paste, the connection area is covered by UV-cured resin 28.

[0034] The substrate holding portion 11 includes a rotating base 112 for fixing the clamping pin 111. The rotating base 112 is disc-shaped and faces the lower surface of the measuring substrate 2. The circuit board 113 is located inside the rotating base 112. Wiring 119 is connected to the circuit board 113. In the example of FIG3, the rotating base 112 has: a circular plate-shaped bottom 114, a circular plate-shaped upper plate 115, an annular outer peripheral wall 116, a central member 117, and a counterweight 118. An annular space is formed in the rotating base 112 by the bottom 114, the upper plate 115, the outer peripheral wall 116, and the central member 117. The circuit board 113 is mounted on the lower surface of the upper plate 115 in this space. To ensure balance during rotation, the counterweight 118 is also mounted on the lower surface of the upper plate 115.

[0035] By placing the circuit board 113 inside the rotating base 112, the circuit board 113 can be arranged without affecting the arrangement of other components. Furthermore, the interior of the rotating base 112 is preferably a sealed space. However, for example, the interior of the rotating base 112 does not necessarily have to be watertight as long as the circuit board 113 has a waterproof structure.

[0036] The circuit board 113 includes circuitry, arithmetic circuitry, a power supply, a wireless communication unit, and memory, which acquire values ​​representing the electrical characteristics between a pair of electrodes on the measurement board 2 via wiring 119. The values ​​representing the electrical characteristics between a pair of electrodes acquired using the circuit board 113 are transmitted to an external wireless communication unit (refer to the wireless communication unit 81 in FIG. 4 described later. The wireless communication unit 81 can be understood as part of the electrical characteristic measurement device 1). Of course, the acquired values ​​can also be transmitted to an external wireless communication unit via other communication standards or optical communication.

[0037] Figure 4 is a block diagram showing the functional configuration of the electrical characteristic measuring device 1, which obtains the value representing the electrical characteristic between one pair of electrodes on the measuring substrate 2 (hereinafter also referred to as "measured value"). The control unit 10 controls the substrate rotation unit 12, the liquid supply unit 14, the circuit board 113 containing the measuring circuit, etc., thereby enabling the electrical characteristic measuring device 1 to perform the operations described later. Furthermore, Figure 4 only shows a portion of the functional configuration of the electrical characteristic measuring device 1. The circuit board 113 includes a switching circuit 31, a measuring circuit 32, a wireless communication unit (transmitting device) 33, and a battery 34. The circuit board 113 may include other memory and general-purpose arithmetic circuits, etc.

[0038] A plurality of electrode pairs 23 (referred to as 23 for convenience, but can be any electrode pair) on the measuring substrate 2 are connected to the switching circuit 31 via wiring 24, connection point 26, and wiring 119. The switching circuit 31 switches the electrode pairs 23 connected to the measuring circuit 32. The measuring circuit 32 obtains the measured values ​​between the electrode pairs 23. The measured values ​​are transmitted via the wireless communication unit 33 to the wireless communication unit 81 (receiving device) outside the device body, and then from the wireless communication unit 81 to the computer, i.e., the arithmetic unit 82, where they are converted into values ​​that are easily usable in the arithmetic unit 82 (e.g., measured values ​​that can be easily identified by the operator). The wireless communication unit 81 and the arithmetic unit 82 can be understood as part of the electrical characteristic measuring device 1, or they can be understood as not constituting elements of the electrical characteristic measuring device 1.

[0039] Figure 5 is a flowchart showing the operation of the electrical characteristic measuring device 1. In the electrical characteristic measuring device 1, firstly, with the measuring substrate 2 held in the substrate holding part 11, the measuring substrate 2 and the substrate holding part 11 are rotated about an axis perpendicular to the measuring substrate 2 by the substrate rotating part 12 (step S11). Secondly, in parallel with the rotation of the measuring substrate 2, electrolyte is supplied from the liquid supply part 14 to the upper surface of the measuring substrate 2 as a pretreatment to set the state of the measuring substrate 2 to a certain level (step S12). In addition, step S12 can be omitted.

[0040] Next, in parallel with the rotation of the measuring substrate 2, a specified liquid related to the measurement is supplied from the liquid supply unit 14 to the measuring substrate 2 (step S13). The liquid can be various processing liquids used for substrate processing, such as organic solvents like IPA (isopropanol), CO2 water, ozone water, phosphoric acid, SPM, SC1, SC2, diluted hydrogen peroxide water, diluted hydrofluoric acid, DIW, etc. In parallel with step S13 or after step S13 is completed, the measuring substrate 2 is rotated, and the measuring circuit 32 repeatedly obtains the measurement value representing the electrical characteristics between the electrode pairs on the measuring substrate 2 (step S14). Furthermore, "in parallel with step S13 or after step S13 is completed" includes the case of "in parallel with step S13 and after step S13 is completed". The obtained value is sent to the computing unit 82 via the wireless communication unit 33 of the circuit board 113 and the external wireless communication unit 81. Then, stop measuring the rotation of substrate 2 (step S15).

[0041] The measured values ​​sent to the calculation unit 82 are converted into usable measured values ​​at any time after step S14 (step S16). Through the above operation, the surface condition (more precisely, the value representing the electrical characteristics between the electrode pairs) of the rotating measurement substrate 2 that is supplied with liquid can be measured in real time. Furthermore, the measured values ​​can be easily obtained in real time using the wireless communication unit 33 and the wireless communication unit 81.

[0042] Furthermore, the electrical characteristic measuring device 1, as already described, also functions as a substrate processing device, and the measuring substrate 2 and the measuring circuit 113 can be separated. The measuring substrate 2 can be separated from the substrate holding portion 11, and the substrate to be processed by the processing liquid is held in the substrate holding portion 11, replacing the measuring substrate 2. In this way, the electrical characteristic measuring device 1 can be used as a substrate processing device. In order to separate the measuring substrate 2 from the measuring circuit 32, for example, the wiring 119 in FIG. 3 can be separated from the connector of the circuit board 113.

[0043] Figure 6 is a graph showing the change in impedance over time when an alternating voltage is applied between the electrode pairs 23 and the impedance (resistivity) between the electrode pairs 23 is obtained as a measurement value. In the measurement shown in Figure 6, the impedance is calculated based on the current value when an alternating voltage with a frequency of 300 Hz and an amplitude of 0.01 V is applied, using the electrode pairs 23 located 20 mm apart from the center of the measurement substrate 2. The impedance at the highest point of the graph is approximately 16000 [Ω], and the length of the horizontal axis is approximately 60 seconds. The impedance is obtained in order to determine the approximate charge on the substrate. That is, the measurement substrate 2 is used to evaluate the charge on the surface of the rotating substrate that passes through the supplied liquid.

[0044] When the impedance is obtained using the electrical characteristic measuring device 1, in step S13, the measuring substrate 2 is rotated and DIW (pure water) is supplied to the measuring substrate 2 from the liquid supply unit 14. Then, during the supply of DIW, a value equivalent to the impedance (that is, a value that substantially represents the impedance) is obtained using the measuring circuit 32 of the circuit board 113, and this value is converted into an impedance value using the calculation unit 82.

[0045] In detail, as a pretreatment, the measurement substrate 2 on which a SiO2 (silicon dioxide) film is formed is rotated and an aqueous NaCl (sodium chloride) solution is supplied to the upper surface of the measurement substrate 2. Then, the measurement substrate 2 is rotated at 10 rpm and coated with DIW, and the measurement substrate 2 is dried by high-speed rotation. Then, the measurement substrate 2 is rotated at 500 rpm and an aqueous NaCl solution is supplied (corresponding to step S12). The measurement substrate 2 is rotated at a specified rotation speed and DIW is supplied as a liquid associated with the measurement to the upper surface of the measurement substrate 2 and the measurement is performed (steps S13, S14).

[0046] The curve of annotation symbol 41 in Figure 6 represents the change in impedance when the measuring substrate 2 is rotated at 50 rpm (the change over time), the curve of annotation symbol 42 represents the change in impedance when the measuring substrate 2 is rotated at 500 rpm, the curve of annotation symbol 43 represents the change in impedance when the measuring substrate 2 is rotated at 800 rpm, the curve of annotation symbol 44 represents the change in impedance when the measuring substrate 2 is rotated at 1200 rpm, and the curve of annotation symbol 45 represents the change in impedance when the measuring substrate 2 is rotated at 1500 rpm.

[0047] As can be seen from curves 41 to 45, the faster the measuring substrate 2 rotates, the faster the impedance decreases from the start of DIW supply. Furthermore, as can be seen from curve 44 at 1500 rpm, the impedance remains close to a certain value. This phenomenon is believed to be caused by the surface becoming charged due to DIW flowing through the surface of the measuring substrate 2.

[0048] In the calculation unit 82 of FIG4, a table showing the relationship between impedance and charge (e.g., charge per unit area) is prepared in advance. Moreover, during the supply of DIW to the measurement substrate 2, the charge on the measurement substrate 2 at the position of electrode pair 23 (charge of a specified area or charge per unit area) is obtained based on the time change of the electrical characteristic value, i.e., impedance, obtained by the measurement circuit 32. That is, by referring to the table, the measured value of impedance is converted into charge, and the charge at the position of electrode pair 23 of the measurement substrate 2 is obtained continuously and in real time. Since the charge is related to the zeta potential, the adhesion of particles to the substrate during processing depends on the zeta potential. By obtaining the charge (or impedance) using the electrical characteristic measurement device 1, the susceptibility of the substrate to the influence of particles during processing, such as cleaning by DIW, can be appropriately evaluated.

[0049] Figures 7A to 7C are diagrams illustrating the phenomenon of impedance change represented by curves 41-45 in Figure 6. First, with the surface of substrate 2, i.e., the SiO2 film, uncharged, as shown in Figure 7A, there are numerous Si-OH terminals at the Si atomic bonds and OH groups on the surface. When DIW flows through this surface, a reaction represented by chemical formula 1 occurs, as shown in Figure 7B, where H3O+ flows out, resulting in a negatively charged surface overall.

[0050] [Chemical Formula 1]

[0051] Moreover, it is believed that when a potential difference is applied between the electrodes (Au is shown in Figures 7A to 7C), proton transitions occur with O- as vacancies, and the surface resistance decreases as the charge increases.

[0052] In this embodiment of impedance measurement, the above effect is approximated by the number 2.

[0053] [Number 2]

[0054] Where Rs is the decrease in surface resistivity (impedance), t is the supply time of DIW, α is a proportionality constant corresponding to the density of Si-OH groups on the surface before charging, τ is a time constant corresponding to the outflow rate of H3O+, and δ is the delay time until the NaCl concentration in the DIW on the surface is sufficiently reduced and the Na+ on the surface is freed. The approximate formula is not limited to number 1.

[0055] Curve 40 in Figure 6 represents the assumed impedance change under the condition that the measuring substrate 2 is uncharged. The formula for 2 is the expression for the difference between curve 40 and curves 41-45. Figure 8 shows the result of fitting the formula 2 using the least squares method to the difference between curve 40 and curves 41-45. That is, it shows the result of fitting the formula 2 to the difference between the time change representing the impedance value obtained under the condition of no charge (curve 40) and the time change representing the impedance value obtained using the measuring circuit 32 (curves 41-45), and determining the values ​​of α, τ, and δ.

[0056] In Figure 8, the horizontal axis represents time, and the vertical axis represents the reduction in impedance. Curves 51-55 correspond to the differences between curves 40 and 41-45, respectively, and change accordingly with the value of τ (where α and δ do not necessarily have to be obtained as common values). Figure 9 shows the curves when the reduction in impedance in Figure 8 is added to the curves in Figure 6, with curves 61-65 corresponding to curves 41-45. As shown in Figure 9, curves 61-65 are roughly consistent, and the models in Figures 7A-7C and the approximation of number 1 are appropriate.

[0057] In the electrical characteristic measuring device 1, after the measurement is completed, the calculation unit 82 obtains the time change of impedance based on α, τ, and δ obtained by fitting as the above formula. In this way, the characteristic of obtaining the time change of charge per unit area at the position of the electrode pair is realized.

[0058] In the above embodiments, the impedance between the electrode pairs is obtained, but the value representing the electrical characteristics between the electrode pairs is not limited to impedance, and various values ​​representing electrical characteristics can be obtained.

[0059] For example, the resistance value when a momentary DC voltage is applied between the electrode pairs can be obtained as a value representing the electrical characteristics between the electrode pairs (between paired electrodes). In this way, the resistance value formed by DC is obtained in the same way as impedance.

[0060] Furthermore, the potential difference (electromotive force) generated between electrodes (e.g., electrode 201 in FIG. 10 described later) located on the measuring substrate 2 at positions separated along the radial direction can be obtained as a value representing the electrical characteristics between the electrode pairs. For example, in the case where a gradient of charge is generated in the DIW along the radial direction of the measuring substrate 2 due to friction between the DIW itself or between the DIW and the surface of the measuring substrate 2, the electromotive force generated between the separated electrodes according to the magnitude of the gradient can be obtained.

[0061] Furthermore, the attenuation rate of the current when a pulse voltage is applied between the electrodes (Ampere method) can be obtained as a value representing the electrical characteristics between the electrode pairs. Since the attenuation rate varies according to the charge of the liquid between the electrode pairs, it can be used as another method for measuring the charge.

[0062] Figure 10 is a diagram illustrating a measurement substrate 2 with a pair of electrodes separated between them. In the measurement substrate 2 of Figure 10, five electrodes 201 are arranged in a straight line along the radial direction, and each electrode 201 is connected to a connection point 203 via wiring 202. When using the measurement substrate 2 of Figure 10, two electrodes 201 are selected from the five electrodes 201 and used as a pair of electrodes. For example, if the center of the measurement substrate 2 is referred to as "electrode 1" to "electrode 5" from the outer periphery, the radial ion concentration distribution on the surface of the measurement substrate 2 can be estimated by measuring impedance between the first and second electrodes, between the first and third electrodes, between the first and fourth electrodes, and between the first and fifth electrodes. Of course, the combination of electrodes is not limited to the above. In this way, in the measurement substrate 2 of Figure 10, various electrical characteristics of the surface of the measurement substrate 2 can be obtained by changing the distance between the electrode pairs.

[0063] In the above embodiment, the control unit 10 controls the substrate rotation unit 12, the liquid supply unit 14, and the measurement circuit 32. During the period when the measurement substrate 2 is rotated and a predetermined liquid is supplied to the measurement substrate 2, a value representing the electrical characteristics between a pair of electrodes is obtained. However, the acquisition of the value representing the electrical characteristics can also be performed after the liquid supply to the measurement substrate 2 has ended. That is, step S13 (liquid supply) in FIG5 can continue between step S14 (acquisition of measurement value) or can end before step S14. By repeatedly acquiring the measurement value after the liquid supply ends, the change in the electrical characteristics of the surface of the measurement substrate 2 after the liquid supply ends can be obtained.

[0064] The electrode pair described above is not limited to planar electrodes. Furthermore, the electrode pair can be disposed on the measurement substrate 2 as part of various sensors, and the electrode pair can be disposed on the measurement substrate 2 in various ways.

[0065] The measuring circuit 32 does not need to be disposed on the circuit board 113. For example, it can be disposed as a circuit molded from resin. Furthermore, the measuring circuit 32 does not need to be disposed in the substrate holding part 11. The measuring circuit 32 can be disposed in various forms as long as it is fixed to the substrate holding part 11, rotates together with the measuring substrate 2, and is electrically connected to the electrode pair.

[0066] The circuit board 113 (or the measuring circuit 32) can be freely attached to and detached from the board holding part 11. For example, a small cover can be provided at the position of the circuit board 113 on the upper plate 115 in FIG3, so that the circuit board 113 and the small cover can be freely attached to and detached from the board holding part 11.

[0067] The posture in which the measuring substrate 2 is held in the substrate holding portion 11 may not be horizontal. The substrate holding portion 11 can hold the measuring substrate 2 in various ways. For example, the substrate holding portion 11 may be a vacuum clamp that holds the substrate by suction.

[0068] The substrate rotating part 12 is preferably an electric motor. The motor can be constructed in various ways. For example, the shaft 121 can be solid or hollow. In the case of using a vacuum clamp, the shaft 121 is preferably hollow. A ring-shaped rotor can be used.

[0069] The liquid supply unit 14 is preferably a supply nozzle, but the supply nozzle can be movable or fixed. Furthermore, the liquid supply unit 14 can supply liquid to the measuring substrate 2 through a structure other than the nozzle.

[0070] The measurement circuit 32 can be fixed to the substrate holding portion 11 in various ways, but the "substrate holding portion 11" here can be broadly interpreted as the mechanism that holds the measurement substrate 2. For example, even if the measurement circuit 32 is actually fixed in the shaft 121, the shaft 121 can be understood as a part of the substrate holding portion 11 because it rotates integrally with the substrate holding portion 11, and can be included in the concept of "fixing the measurement circuit 32 to the substrate holding portion 11".

[0071] The measuring substrate 2 is not limited to a semiconductor substrate. It may be a glass substrate for photomasks, a glass substrate for liquid crystal displays, a glass substrate for plasma displays, a substrate for FED (Field Emission Display), a substrate for optical discs, a substrate for magnetic discs, and a substrate for optical discs, etc.

[0072] The above-mentioned implementation forms and variations can be appropriately combined as long as they do not contradict each other.

[0073] Although the invention has been described in detail, the description is illustrative and not limiting. Therefore, many variations and modifications can be made without departing from the scope of the invention. [Simplified Explanation of the Diagram]

[0020] Figure 1 is a front view showing the general structure of the electrical characteristic measuring device. Figure 2 is a top view of the measuring substrate. Figure 3 is a longitudinal sectional view of the substrate holding part and the measuring substrate. Figure 4 is a block diagram showing the functional structure for obtaining values ​​representing electrical characteristics. Figure 5 is a flowchart showing the operation of the electrical characteristic measuring device. Figure 6 is a graph showing the time change of impedance. Figure 7A is a model diagram showing the phenomenon of impedance change. Figure 7B is a model diagram showing the phenomenon of impedance change. Figure 7C is a model diagram showing the phenomenon of impedance change. Figure 8 is a graph showing the result of fitting a formula to the difference between the assumed impedance and the measured impedance under the assumption of no charge. Figure 9 is a graph showing the curve after adding the impedance reduction in Figure 8 to the curve in Figure 6. Figure 10 is a graph illustrating the measuring substrate with electrodes separated.

Claims

1. An electrical characteristic measuring device, comprising: a measuring substrate having a pair of electrodes formed on its upper surface; a substrate holding portion holding the measuring substrate; a substrate rotating portion rotating the measuring substrate about an axis perpendicular to the measuring substrate; a liquid supply portion supplying a predetermined liquid to the measuring substrate; a measuring circuit fixed to the substrate holding portion, rotating together with the measuring substrate, electrically connected to the pair of electrodes, and obtaining a value representing the electrical characteristics between the pair of electrodes; and a control portion controlling the substrate rotating portion, the liquid supply portion, and the measuring circuit to obtain the value representing the electrical characteristics between the pair of electrodes during or after the supply of the predetermined liquid to the measuring substrate while rotating the measuring substrate.

2. The electrical characteristic measuring device of claim 1, further comprising a wireless communication unit; and transmitting from the aforementioned wireless communication unit a value representing the aforementioned electrical characteristic between the aforementioned pair of electrodes.

3. The electrical characteristic measuring apparatus of claim 1, wherein the measuring substrate and the measuring circuit are separable; the substrate holding part can hold the substrate of the object to be treated with the processing liquid and replace the measuring substrate.

4. The electrical characteristic measuring device of claim 1, further comprising: a calculation unit that calculates the charge on the aforementioned measuring substrate at the position of the aforementioned pair of electrodes based on the time change of the value representing the aforementioned electrical characteristic obtained by the aforementioned measuring circuit.

5. The electrical characteristic measuring apparatus of claim 4, wherein during the period when the measuring substrate is rotated while pure water is supplied to the measuring substrate from the liquid supply unit, the time change representing the impedance value is obtained by the measuring circuit as a value representing the electrical characteristic; and the calculation unit obtains the values ​​of α, τ, and δ by fitting the difference between the time change representing the impedance value imagined to be obtained in a de-energized state and the time change representing the impedance value obtained by the measuring circuit as follows: [number 1], wherein, t is the supply time of pure water, α is a proportionality constant, τ is a time constant, and δ is the delay time.

6. The electrical characteristic measuring apparatus of claim 1, wherein a plurality of pairs of electrodes, including the aforementioned pair of electrodes, are provided on the aforementioned measuring substrate; and the plurality of pairs of electrodes are arranged at different positions in the radial direction of the aforementioned measuring substrate.

7. An electrical characteristic measuring device according to any one of claims 1 to 6, wherein the aforementioned substrate rotating portion includes a disk-shaped rotating base facing the lower surface of the aforementioned measuring substrate; and the aforementioned measuring circuit is located inside the aforementioned rotating base.

8. A measuring substrate for evaluating the charge on an upper surface supplied with liquid while rotating, and comprising: a plurality of pairs of electrodes disposed on the upper surface; a plurality of wires extending from the plurality of pairs of electrodes to an outer edge of the upper surface; and a plurality of connection points, which are the ends of the plurality of wires in the outer edge for electrical connection to the outside.

9. A method for measuring electrical characteristics, comprising the following steps: a) holding a measuring substrate on which a pair of electrodes are formed on its upper surface and rotating the measuring substrate about an axis perpendicular to the measuring substrate; b) supplying a specified liquid onto the measuring substrate in parallel with step a); and c) obtaining a value representing the electrical characteristics between the pair of electrodes in parallel with step b) or after step b).

10. The method for measuring electrical characteristics as claimed in claim 9, wherein, prior to step a) before step b), the method further includes the following step: d) supplying electrolyte onto the aforementioned measuring substrate.

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