Electrical characteristic measurement device, measurement substrate, and electrical characteristic measurement method

Abstract

This electrical characteristic measurement device comprises: a measurement substrate (2) having a pair of electrodes formed on the upper surface; a substrate holding unit (11) that holds the measurement substrate (2); a substrate rotation unit that rotates the measurement substrate (2) about an axis perpendicular to the measurement substrate (2); a liquid supply unit that supplies a predetermined liquid onto the measurement substrate (2); a measurement circuit that is fixed to the substrate holding unit (11), rotates together with the measurement substrate (2), is electrically connected to the pair of electrodes, and acquires a value indicating an electrical characteristic between the pair of electrodes; and a control unit that controls the substrate rotation unit, the liquid supply unit, and the measurement circuit, thereby acquiring the value indicating the electrical characteristic between the pair of electrodes during or after the supply of the predetermined liquid onto the measurement substrate (2) while the measurement substrate (2) is rotating.

Description

Electrical characteristic measuring device, measurement substrate, and electrical characteristic measuring method

[0001] The present invention relates to a technique for measuring electrical properties of a substrate surface. [Reference to Related Applications] This application claims the benefit of priority from Japanese Patent Application JP2024-148477, filed on August 30, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] Various proposals have been made to measure the conditions of a semiconductor substrate processing process. For example, JP-A 2007-536726 proposes providing a sensor and a transmitter on a substrate to measure the temperature, pressure, force, strain, flow rate, chemical concentration of a gas, or ion current density or ion current energy in a structure such as a parallel plate during processing.

[0003] On the other hand, Japanese Patent Laid-Open Publication No. 9-292358 discloses a technology in which a sensing section is formed on one side of a semiconductor substrate, a probe light is emitted to the other side to extract a signal, and a liquid sample containing microparticles for electrophoresis is placed on the sensing section, thereby measuring the zeta potential.

[0004] The technology of processing a substrate by supplying a liquid to a rotating substrate is used in a variety of processes, but accurate research and development has been difficult because it is not possible to measure the surface condition of the substrate in real time.

[0005] The present invention aims to measure in real time the surface condition of a substrate onto which a liquid is supplied while rotating.

[0006] A first aspect of the present invention is an electrical characteristic measuring device comprising: a measurement substrate having a pair of electrodes formed on an upper surface thereof; a substrate holding unit that holds the measurement substrate; a substrate rotation unit that rotates the measurement substrate around an axis perpendicular to the measurement substrate; a liquid supply unit that supplies a predetermined liquid onto the measurement substrate; a measurement circuit that is fixed to the substrate holding unit and rotates together with the measurement substrate, is electrically connected to the pair of electrodes, and acquires a value indicating the electrical characteristic between the pair of electrodes; and a control unit that controls the substrate rotation unit, the liquid supply unit, and the measurement circuit to acquire a value indicating the electrical characteristic between the pair of electrodes while rotating the measurement substrate and supplying the predetermined liquid onto the measurement substrate, by controlling the substrate rotation unit, the liquid supply unit, and the measurement circuit.

[0007] According to the present invention, it is possible to measure in real time the surface state of a substrate onto which a liquid is supplied while the substrate is rotating.

[0008] A second aspect of the present invention is the electrical characteristic measuring device of the first aspect, further comprising a wireless communication unit, and a value indicating the electrical characteristic between the pair of electrodes is transmitted from the wireless communication unit.

[0009] Aspect 3 of the present invention is an electrical characteristic measuring device of aspect 1 (which may be aspect 1 or 2), in which the measurement substrate and the measurement circuit are separable, and the substrate holding portion can hold a substrate to be treated with a treatment liquid instead of the measurement substrate.

[0010] Aspect 4 of the present invention is an electrical characteristic measuring device according to aspect 1 (which may be any one of aspects 1 to 3), further comprising a calculation unit that calculates the amount of charge on the measurement substrate at the position of the pair of electrodes based on the temporal change in the value indicating the electrical characteristic obtained by the measurement circuit.

[0011] A fifth aspect of the present invention is the electrical characteristic measuring device of the fourth aspect, wherein while the measurement substrate is being rotated and pure water is being supplied onto the measurement substrate from the liquid supply unit, the measurement circuit acquires a time change in a value indicating impedance as a value indicating the electrical characteristic, and the calculation unit calculates a time difference between the time change in the value indicating impedance that is expected to be acquired in a state without electrostatic charge and the time change in the value indicating impedance acquired by the measurement circuit,

[0012]

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

[0014] Aspect 6 of the present invention is an electrical characteristic measuring device of aspect 1 (which may be any one of aspects 1 to 5), in which multiple pairs of electrodes including the pair of electrodes are provided on the measurement substrate, and the multiple pairs of electrodes are arranged at different positions in the radial direction of the measurement substrate.

[0015] Aspect 7 of the present invention is an electrical characteristic measuring device according to any one of aspects 1 to 6, wherein the substrate rotating unit includes a disk-shaped rotating base facing the underside of the measurement substrate, and the measurement circuit is located inside the rotating base.

[0016] Aspect 8 of the present invention is a measurement substrate used to evaluate the amount of charge on an upper surface onto which a liquid is supplied while rotating, and comprises multiple pairs of electrodes provided on the upper surface, multiple wirings extending from the multiple pairs of electrodes to the outer edge of the upper surface, and multiple connection points which are ends of the multiple wirings at the outer edge and are used for electrical connection to the outside.

[0017] A ninth aspect of the present invention is an electrical characteristic measurement method comprising the steps of: a) holding a measurement substrate having a pair of electrodes formed on its upper surface and rotating the measurement substrate around an axis perpendicular to the measurement substrate; b) supplying a predetermined liquid onto the measurement substrate in parallel with step a); and c) acquiring a value indicating the electrical characteristic between the pair of electrodes in parallel with step b) or after step b).

[0018] A tenth aspect of the present invention is the electrical characteristic measuring method of the ninth aspect, further comprising the step of: d) supplying an electrolyte onto the measurement substrate during the step a) prior to the step b).

[0019] The above and other objects, features, aspects and advantages will become more apparent from the following detailed description of the invention which proceeds with reference to the accompanying drawings.

[0020] 1 is a front view showing a schematic configuration of an electrical characteristic measuring device; FIG. 2 is a plan view of a measurement substrate; FIG. 3 is a longitudinal cross-sectional view of a substrate holding unit and a measurement substrate; FIG. 4 is a block diagram showing a functional configuration for acquiring values ​​indicating electrical characteristics; FIG. 5 is a diagram showing the flow of operation of an electrical characteristic measuring device; FIG. 6 is a diagram showing changes in impedance over time; FIG. 7 is a diagram showing a model for explaining the phenomenon of changes in impedance; FIG. 8 is a diagram showing a model for explaining the phenomenon of changes in impedance; FIG. 9 is a diagram showing a model for explaining the phenomenon of changes in impedance; FIG. 10 is a diagram showing the results of fitting a mathematical formula to the difference between the impedance expected when there is no charge and the measured impedance; FIG. 11 is a diagram showing a curve obtained by adding the amount of impedance decrease in FIG. 8 to the curve in FIG. 6; FIG. 12 is a diagram illustrating a measurement substrate in which the electrodes are spaced apart.

[0021] FIG. 1 is a front view showing a schematic configuration of an electrical characteristic measuring apparatus 1 according to one embodiment of the present invention. FIG. 1 shows a portion of the electrical characteristic measuring apparatus 1 in longitudinal cross section. The electrical characteristic measuring apparatus 1 is a modified version of a typical single-wafer substrate processing apparatus, further comprising a substrate 2 for measurement (hereinafter simply referred to as a "measurement substrate" or "substrate"). The electrical characteristic measuring apparatus 1 includes a substrate holding unit 11, a substrate rotating unit 12, a cup unit 13, multiple liquid supply units 14, and a housing 15. The substrate holding unit 11, the substrate rotating unit 12, the cup unit 13, and the liquid supply unit 14 are housed in the interior space of the housing 15. An airflow generating unit 151 is provided in the canopy of the housing 15 to supply gas into the interior space and generate a downward airflow (so-called downflow). An FFU (fan filter unit), for example, is used as the airflow generating unit 151. The electrical characteristic measuring apparatus 1 further includes a control unit (not shown), which controls the substrate holding unit 11, the substrate rotating unit 12, the cup unit 13, and the liquid supply unit .

[0022] The substrate holding part 11 holds the measurement substrate 2 in a horizontal position. The substrate holding part 11 grips the outer periphery of the measurement substrate 2 with chuck pins 111.

[0023] The substrate rotation unit 12 is disposed below the substrate holding unit 11. The substrate rotation unit 12 rotates the measurement substrate 2 together with the substrate holding unit 11 around a rotation axis J1 oriented in the vertical direction. This causes the measurement substrate 2 to rotate around an axis perpendicular to the measurement substrate 2. The substrate rotation unit 12 includes a shaft 121 and a motor 122. The shaft 121 is a substantially columnar or cylindrical member centered on the rotation axis J1. The shaft 121 extends in the vertical direction and is connected to the center of the underside of the substrate holding unit 11. The motor 122 is an electric rotary motor that rotates the shaft 121. Note that the substrate rotation unit 12 may be a motor having another structure (for example, a hollow motor, etc.).

[0024] The liquid supply unit 14 is a supply nozzle that supplies a predetermined liquid to the surface of the measurement substrate 2 held by the substrate holder 11. The liquid supply unit 14 may also include a configuration that guides the liquid to the supply nozzle. Examples of liquids include chemicals such as SPM (Sulfuric Acid Hydrogen Peroxide Mixture), SC1 (Ammonia Hydrogen Peroxide Mixture), SC2 (Hydrogen Acid Hydrogen Peroxide Mixture), diluted hydrogen peroxide, and DIW (Deionized Water) as a rinse liquid. In the following description, these liquids may be referred to as "processing liquids." While FIG. 1 shows two nozzles as the liquid supply unit 14 that eject liquid from above the measurement substrate 2 toward the upper surface of the measurement substrate 2, other nozzles may also be provided. The ejection outlet of each liquid supply unit 14 can be moved between a position above the measurement substrate 2 and a position away from the measurement substrate 2 by a nozzle movement mechanism (not shown).

[0025] The cup portion 13 has an annular cup centered on the rotation axis J1, and the cup receives liquid such as the processing liquid that splashes toward the periphery from the rotating measurement substrate 2. A drain port (not shown) is provided at the bottom of the cup portion 13 to discharge the processing liquid received in the cup to the outside of the housing 15. In reality, multiple cups are arranged concentrically, and each cup is movable up and down. Each cup receives a specific liquid that splashes from the measurement substrate 2.

[0026] FIG. 2 is a plan view of the measurement substrate 2. The measurement substrate 2 is a semiconductor substrate with a diameter of 300 mm on which electrodes, wiring, etc. are formed. As shown in FIG. 2, a plurality of electrode pairs 21, 22, and 23 are formed on the upper surface of the measurement 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 and 26 are also provided on the upper surface. The connection points 25 and 26 are also the ends of the plurality of wirings 24 at the outer edge and are used for electrical connection to the outside. If the wirings 24 and the connection points 25 and 26 are considered to be separate components, the wirings 24 connect the plurality of electrode pairs 21, 22, and 23 to the plurality of connection points 25 and 26.

[0027] In the electrode pair 21, rectangular electrodes are arranged close to each other. For example, the cell constant is 550,000 cm －１ , electrode length 10 mm, and inter-electrode distance 1 mm. In the example of FIG. 2, three electrode pairs 21 are arranged linearly in the radial direction on the upper side of FIG. 2. In the electrode pair 22, the comb-shaped electrodes are arranged close to each other so that the teeth of one comb are located between the teeth of the other comb. For example, when the cell constant is 300 cm －１ The electrode length is 740 mm, the distance between the electrodes is 40 μm, and the number of comb teeth of each electrode is 63. In the example of FIG. 2 , seven electrode pairs 22 are arranged linearly in the radial direction from the center of FIG. 2 toward the upper right, and two electrode pairs 22 are arranged from the center of FIG. 2 toward the lower right.

[0028] In the electrode pair 23, the comb-shaped electrodes are arranged close to each other so that the teeth of one comb are present between the teeth of the other comb. For example, －１ The electrode length is 185 mm, the distance between the electrodes is 10 μm, and the number of comb teeth of each electrode is 63. In the example of FIG. 2 , eight electrode pairs 23 are arranged linearly in the radial direction from the center of FIG. 2 to the right, and two electrode pairs 23 are arranged on the lower side of FIG. 2 .

[0029] In this way, in the measurement substrate 2, multiple pairs of electrodes are arranged at different positions in the radial direction of the measurement substrate 2, making it possible to obtain electrical characteristics at various positions in the radial direction of the measurement substrate 2.

[0030] Connection point 25 is a pad for electrically connecting to external wiring with silver paste. Connection point 26 is a pad for connecting connector part 27 shown by a two-dot chain line with silver paste. Connector part 27 electrically connects wiring 24 to external wiring.

[0031] The electrode pairs 21, 22, 23 and the wiring 24 are formed, for example, from gold (Au) with a thickness of 180 nm. The connection points 25, 26 have a structure in which nickel (Ni) with a thickness of 250 nm is layered on titanium (Ti) with a thickness of 30 nm. Three types of electrode pairs 21, 22, 23 are provided on the measurement substrate 2 to perform various measurement evaluations. The electrode pairs are planar electrodes so as not to interfere with the flow of liquid on the measurement substrate 2, which will be described later.

[0032] 3 is a longitudinal cross-sectional view of the substrate holding part 11 and the measurement substrate 2. The parallel diagonal lines indicating the cross section have been partially omitted. The measurement substrate 2 and the substrate holding part 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 26 on the measurement substrate 2 via silver paste or a connector part 27. This electrically connects the wiring 119 to the wiring 24 on the measurement substrate 2. In other words, a predetermined electrode pair is connected to the wiring 119.

[0033] 2 is merely an example, and in the example of Fig. 2, the wiring 119 is connected to some of the connection points 25, 26, but the number of conductors in the wiring 119 may be the same as the number of connection points, and the wiring 119 may be connected to all of the connection points, depending on the layout of the electrode pairs, wiring, and connection points on the measurement substrate 2. When the wiring 119 and the connection points 25 are connected with silver paste, the connection points are covered with UV-curable resin 28.

[0034] The substrate holder 11 includes a rotary base 112 to which the chuck pins 111 are fixed. The rotary base 112 is disk-shaped and faces the underside of the measurement substrate 2. A circuit board 113 is located inside the rotary base 112. Wiring 119 is connected to the circuit board 113. In the example of FIG. 3 , the rotary base 112 has a disk-shaped bottom 114, a disk-shaped upper plate 115, an annular outer peripheral wall 116, a central member 117, and a counterweight 118. The bottom 114, the upper plate 115, the outer peripheral wall 116, and the central member 117 form an annular space within the rotary base 112. Within this space, the circuit board 113 is attached to the underside of the upper plate 115. A counterweight 118 is also attached to the underside of the upper plate 115 to ensure balance during rotation.

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

[0036] The circuit board 113 includes a circuit for acquiring values ​​indicating electrical characteristics between a pair of electrodes on the measurement board 2 via wiring 119, an arithmetic circuit, a power supply, a wireless communication unit, a memory, etc. The values ​​indicating electrical characteristics between the pair of electrodes acquired by the circuit board 113 are sent via the wireless communication unit to an external wireless communication unit (see the wireless communication unit 81 in FIG. 4 described below; however, the wireless communication unit 81 may be considered as part of the electrical characteristic measuring device 1) in accordance with a standard such as Bluetooth (registered trademark). Of course, the acquired values ​​may also be sent to the external wireless communication unit via other communication standards, optical communication, etc.

[0037] FIG. 4 is a block diagram showing the functional configuration of the electrical characteristic measuring apparatus 1 for acquiring a value (hereinafter also referred to as a "measured value") indicating an electrical characteristic between a pair of electrodes on a measurement substrate 2. The control unit 10 controls the substrate rotation unit 12, the liquid supply unit 14, the circuit board 113 including the measurement circuit, etc., thereby causing the electrical characteristic measuring apparatus 1 to perform the operations described below. Note that FIG. 4 shows only a portion of the functional configuration of the electrical characteristic measuring apparatus 1. The circuit board 113 includes a switching circuit 31, a measurement circuit 32, a wireless communication unit (transmitter) 33, and a battery 34. The circuit board 113 may also include a memory, a general-purpose arithmetic circuit, etc.

[0038] A plurality of electrode pairs 23 (here, for convenience, the reference numeral 23 is used, but any electrode pairs may be used) on the measurement substrate 2 are connected to a switching circuit 31 via wiring 24, connection points 26, and wiring 119. The switching circuit 31 switches the electrode pairs 23 to be connected to a measurement circuit 32. The measurement circuit 32 acquires measurements between the electrode pairs 23. The measurements are sent via a wireless communication unit 33 to a wireless communication unit 81 (receiving device) external to the device body, and further sent from the wireless communication unit 81 to a calculation unit 82, which is a computer, where the measurements are converted into easily usable values ​​(e.g., measurement values ​​that can be easily recognized by an operator). The wireless communication unit 81 and the calculation unit 82 may be considered to be part of the electrical characteristic measuring device 1, or may be considered to be elements that do not constitute the electrical characteristic measuring device 1.

[0039] 5 is a diagram showing the operation flow of the electrical characteristic measuring apparatus 1. In the electrical characteristic measuring apparatus 1, first, with the measurement substrate 2 held by the substrate holding unit 11, the substrate rotation unit 12 starts rotating the measurement substrate 2 and the substrate holding unit 11 around an axis perpendicular to the measurement substrate 2 (step S11). Next, in parallel with the rotation of the measurement substrate 2, an electrolyte is supplied from the liquid supply unit 14 to the upper surface of the measurement substrate 2 as a pretreatment to stabilize the state on the measurement substrate 2 (step S12). Note that step S12 may be omitted.

[0040] Next, in parallel with the rotation of the measurement substrate 2, a predetermined liquid related to the measurement is supplied onto the measurement substrate 2 from the liquid supply unit 14 (step S13). The liquid may be any of various processing liquids used for processing the substrate, for example, organic solvents such as IPA (isopropyl alcohol), CO ２ Examples of suitable solvents include water, ozone water, phosphoric acid, SPM, SC1, SC2, diluted hydrogen peroxide, diluted hydrofluoric acid, and DIW. In parallel with step S13 or after step S13 is completed, the measurement circuit 32 repeatedly acquires measured values ​​indicating the electrical characteristics between the electrode pairs on the measurement substrate 2 while rotating the measurement substrate 2 (step S14). Note that "in parallel with step S13 or after step S13 is completed" includes "in parallel with step S13 and after step S13 is completed." The acquired values ​​are sent to the calculation unit 82 via the wireless communication unit 33 of the circuit substrate 113 and the external wireless communication unit 81. Then, the rotation of the measurement substrate 2 is stopped (step S15).

[0041] The measurement values ​​sent to the calculation unit 82 are processed at any timing after step S14 and converted into usable measurement values ​​(step S16). The above operation allows the surface condition of the measurement substrate 2 (more precisely, the value indicating the electrical characteristics between the electrode pairs) to be measured in real time as the measurement substrate 2 rotates and receives the liquid. Furthermore, by using the wireless communication units 33 and 81, measurement values ​​can be easily acquired in real time.

[0042] As already explained, the electrical characteristic measuring apparatus 1 also functions as a substrate processing apparatus, and the measurement substrate 2 and the measurement circuit 113 are separable. The measurement substrate 2 can be separated from the substrate holding unit 11, and the substrate holding unit 11 can hold a substrate to be processed with a processing solution in place of the measurement substrate 2. This allows the electrical characteristic measuring apparatus 1 to be used as a substrate processing apparatus. To enable the measurement substrate 2 and the measurement circuit 32 to be separated, for example, the wiring 119 in FIG. 3 and the connector of the circuit board 113 are made separable.

[0043] FIG. 6 shows the change in impedance over time when an AC voltage is applied between the electrode pair 23 and the impedance (resistivity) between the electrode pair 23 is obtained as a measured value. In the measurement shown in FIG. 6 , the electrode pair 23 located 20 mm from the center of the measurement substrate 2 was used, and the impedance was calculated from the current value when an AC voltage of 300 Hz and 0.01 V was applied. The impedance at the highest point on the graph was approximately 16,000 [Ω], and the horizontal axis length was approximately 60 seconds. The impedance was obtained to determine the approximate amount of charge on the substrate. In other words, the measurement substrate 2 was used to evaluate the amount of charge on the upper surface to which liquid was supplied while rotating.

[0044] When the impedance is acquired by the electrical characteristic measuring apparatus 1, in step S13, the measurement substrate 2 is rotated while DIW (pure water) is supplied onto the measurement substrate 2 from the liquid supply unit 14. Then, while the DIW is being supplied, a value corresponding to the impedance (i.e., a value that substantially indicates the impedance) is acquired by the measurement circuit 32 of the circuit board 113, and this value is converted into an impedance value by the calculation unit 82.

[0045] In detail, as a pretreatment, SiO ２ While rotating the measurement substrate 2 on which the silicon dioxide film was formed, an NaCl (sodium chloride) aqueous solution was supplied to the upper surface of the measurement substrate 2, and then the measurement substrate 2 was puddled with DIW while rotating at 10 rpm, and the measurement substrate 2 was dried by high-speed rotation. Then, while rotating the measurement substrate 2 at 500 rpm, an NaCl aqueous solution was supplied (corresponding to step S12), and while rotating the measurement substrate 2 at a predetermined rotation speed, DIW was supplied to the upper surface of the measurement substrate 2 as a liquid related to the measurement, and measurement was performed (steps S13 and S14).

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

[0047] Curves 41 to 45 show that the faster the rotation of the measurement substrate 2, the faster the impedance decreases after the supply of DIW begins. Also, curve 44 at 1500 rpm shows that the impedance approaches a constant value. This phenomenon is thought to be due to the surface of the measurement substrate 2 becoming charged as DIW flows over it.

[0048] The calculation unit 82 in FIG. 4 is provided with a table indicating the relationship between impedance and charge amount (e.g., charge amount per unit area). Then, while DIW is being supplied to the measurement substrate 2, the charge amount (charge amount in a predetermined area or charge amount per unit area) on the measurement substrate 2 at the position of the electrode pair 23 is calculated based on the temporal change in impedance, which is a value indicating an electrical characteristic acquired by the measurement circuit 32. That is, the measured impedance value is converted into charge amount by referring to the table, and the charge amount at the position of the electrode pair 23 on the measurement substrate 2 is continuously acquired in real time. Since charge amount is correlated with zeta potential and particle adhesion to a substrate during processing depends on the zeta potential, acquiring charge amount (or impedance) using the electrical property measuring device 1 allows appropriate evaluation of the susceptibility of a substrate to particle influence during processing, for example, during cleaning with DIW.

[0049] 7A to 7C are diagrams showing models for explaining the phenomenon of the change in impedance shown by the curves 41 to 45 in FIG. ２When the film is not charged, there are many Si-OH terminations on the surface, where OH groups are bonded to Si atoms, as shown in Figure 7A. When DIW flows on this surface, the reaction shown in Chemical Formula 1 occurs, and as shown in Figure 7B, H ３ O ＋ When this flows out, the entire surface becomes negatively charged.

[0050]

[0051] When a potential difference is applied between the electrodes (shown as Au in FIGS. 7A to 7C), O － It is thought that proton hopping occurs through these vacancies, and the surface resistance decreases as the amount of charge increases.

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

[0053]

[0054] where Rs is the amount of decrease in surface resistance (impedance), t is the DIW supply time, α is a proportionality constant depending on the density of Si—OH groups on the surface before charging, and τ is H ３ O ＋ The time constant corresponding to the outflow rate of the NaCl in the DIW on the surface is sufficiently decreased, and δ is the time when the NaCl concentration in the DIW on the surface is sufficiently decreased. ＋ is the delay time until the molecule is released. The approximation formula is not limited to Equation 1.

[0055] The curve labeled 40 in FIG. 6 represents the change in impedance that is expected when it is assumed that there is no charge on the measurement substrate 2. Equation 2 is an equation that expresses the difference between curve 40 and each of curves 41 to 45. FIG. 8 is a diagram showing the results of fitting Equation 2 to the difference between curve 40 and each of curves 41 to 45 using the least squares method. That is, the diagram shows the results of determining the values ​​of α, τ, and δ by fitting Equation 2 to the difference between the change over time in the value indicating the impedance that is expected to be obtained in the absence of charge (curve 40) and the change over time in the value indicating the impedance obtained by the measurement circuit 32 (curves 41 to 45).

[0056] The horizontal axis of Figure 8 represents time, and the vertical axis represents the amount of impedance decrease. Curves 51 to 55 correspond to the difference between curve 40 and curves 41 to 45, respectively, and vary depending on the value of τ (however, α and δ do not necessarily have to be determined as common values). Figure 9 shows the curves obtained when the amount of impedance decrease in Figure 8 is added to the curves in Figure 6, with curves 61 to 65 corresponding to curves 41 to 45, respectively. As shown in Figure 9, curves 61 to 65 nearly coincide, indicating that the models in Figures 7A to 7C and the approximation formula in Equation 1 are appropriate.

[0057] After the measurement is completed in the electrical characteristic measuring apparatus 1, the calculation unit 82 obtains the time change in impedance as the above formula based on α, τ, and δ obtained by fitting, thereby realizing the acquisition of the characteristics of the time change in the charge amount per unit area at the position of the electrode pair.

[0058] In the above embodiment, the impedance between the electrode pair is acquired, but the value indicating the electrical characteristic between the electrode pair is not limited to impedance, and values ​​indicating various electrical characteristics may be acquired.

[0059] For example, the resistance value when a DC voltage is applied instantaneously between the electrode pair may be acquired as a value indicating the electrical characteristics between the electrode pair (between the electrodes forming a pair). In this way, the DC resistance value is acquired in the same way as the impedance.

[0060] Furthermore, the potential difference (electromotive force) generated between electrodes (e.g., electrode 201 in FIG. 10 described later) spaced apart in the radial direction of the measurement substrate 2 may be acquired as a value indicating the electrical characteristics between the electrode pair. For example, if a gradient in the amount of charge occurs in the DIW in the radial direction of the measurement substrate 2 due to friction between the DIW itself or the DIW and the surface of the measurement substrate 2, the electromotive force generated between the spaced apart electrodes is acquired according to the magnitude of this gradient.

[0061] Furthermore, the decay rate of the current (amperometry) when a pulse voltage is applied between the electrodes may be obtained as a value indicating the electrical characteristics between the electrode pair. Because the decay rate changes depending on the amount of charge in the liquid between the electrode pair, this can be used as another method for measuring the amount of charge.

[0062] FIG. 10 illustrates a measurement substrate 2 in which a pair of electrodes is spaced apart. In the measurement substrate 2 of FIG. 10, five electrodes 201 are arranged in a radial line, and each electrode 201 is connected to a connection point 203 via a wiring 202. When the measurement substrate 2 of FIG. 10 is used, two of the five electrodes 201 are selected and used as a pair of electrodes. For example, if the electrodes 201 are labeled "first electrode" through "fifth electrode" from the center to the periphery of the measurement substrate 2, 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 electrode combinations are not limited to those described above. In this way, the measurement substrate 2 of FIG. 10 allows the distance between the electrode pairs to be changed, allowing various electrical characteristics of the surface of the measurement substrate 2 to be obtained.

[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 to acquire values ​​indicating the electrical characteristics between the pair of electrodes while rotating the measurement substrate 2 and supplying a predetermined liquid onto the measurement substrate 2, but acquisition of the values ​​indicating the electrical characteristics may also be performed after the supply of liquid to the measurement substrate 2 has finished. That is, step S13 (supply of liquid) in Fig. 5 may be continued during step S14 (acquisition of measured values), or may be completed before step S14. By repeatedly acquiring measured values ​​after the supply of liquid has finished, it is possible to acquire changes in the electrical characteristics of the surface of the measurement substrate 2 since the supply of liquid has finished.

[0064] The electrode pairs in the above description are not limited to planar electrodes. The electrode pairs may also be provided on the measurement substrate 2 as part of various sensors, and the electrode pairs may be provided on the measurement substrate 2 in various ways.

[0065] The measurement circuit 32 does not need to be provided on the circuit board 113, but may be provided as a circuit molded with resin, for example. Furthermore, the measurement circuit 32 does not need to be provided inside the substrate holding part 11. The measurement circuit 32 may be provided in various forms as long as it is fixed to the substrate holding part 11, rotates together with the measurement substrate 2, and is electrically connected to the electrode pairs.

[0066] The circuit board 113 (or the measurement circuit 32) may be detachable from the board holder 11. For example, a small cover may be provided at the position of the circuit board 113 on the upper plate 115 in FIG. 3 , and the circuit board 113 may be detachable from the board holder 11 together with the small cover.

[0067] The measurement substrate 2 does not have to be held horizontally by the substrate holder 11. The substrate holder 11 may hold the measurement substrate 2 in various ways. For example, the substrate holder 11 may be a vacuum chuck that holds the measurement substrate 2 by suction.

[0068] The substrate rotating unit 12 is preferably an electric motor. Various motor structures may be used. For example, the shaft 121 may be solid or hollow. When a vacuum chuck is used, the shaft 121 is preferably hollow. An annular rotor may also be used.

[0069] The liquid supply unit 14 is preferably a supply nozzle, but the supply nozzle may be either movable or fixed. Furthermore, the liquid supply unit 14 may supply the liquid onto the measurement substrate 2 by a structure other than a nozzle.

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

[0071] The measurement substrate 2 is not limited to a semiconductor substrate, but may also be a glass substrate for a photomask, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, or the like.

[0072] The configurations of the above-described embodiment and each modification may be combined as appropriate as long as they are not mutually contradictory.

[0073] While the invention has been particularly illustrated and described, it should be understood that the foregoing description is illustrative and not restrictive, and that numerous modifications and variations are possible without departing from the scope of the invention.

[0074] REFERENCE SIGNS LIST 1 Electrical characteristic measuring device 2 Measurement substrate 10 Control unit 11 Substrate holding unit 12 Substrate rotation unit 14 Liquid supply unit 21, 22, 23 Electrode pair 24 Wiring 25, 26 Connection point 32 Measurement circuit 33 Wireless communication unit 82 Calculation unit 112 Rotation base S11 to S16 Steps

Claims

1. An electrical characteristic measuring device comprising: a measurement substrate having a pair of electrodes formed on an upper surface thereof; a substrate holding unit that holds the measurement substrate; a substrate rotation unit that rotates the measurement substrate around an axis perpendicular to the measurement substrate; a liquid supply unit that supplies a predetermined liquid onto the measurement substrate; a measurement circuit that is fixed to the substrate holding unit and rotates together with the measurement substrate, is electrically connected to the pair of electrodes, and acquires a value indicating the electrical characteristic between the pair of electrodes; and a control unit that controls the substrate rotation unit, the liquid supply unit, and the measurement circuit to acquire a value indicating the electrical characteristic between the pair of electrodes while rotating the measurement substrate and supplying the predetermined liquid onto the measurement substrate, by controlling the substrate rotation unit, the liquid supply unit, and the measurement circuit.

2. An electrical characteristic measuring device according to claim 1, further comprising a wireless communication unit, wherein a value indicating the electrical characteristic between the pair of electrodes is transmitted from the wireless communication unit.

3. An electrical characteristic measuring device according to claim 1, wherein the measurement substrate and the measurement circuit are separable, and the substrate holding unit is capable of holding a substrate to be treated with a treatment liquid instead of the measurement substrate.

4. An electrical characteristic measuring device as claimed in claim 1, further comprising a calculation unit that calculates the amount of charge on the measurement substrate at the position of the pair of electrodes based on the temporal change in the value indicating the electrical characteristic obtained by the measurement circuit.

5. An electrical characteristic measuring device according to claim 4, wherein, while the measurement substrate is being rotated and pure water is being supplied onto the measurement substrate from the liquid supply unit, the measurement circuit acquires a time change in a value indicating impedance as a value indicating the electrical characteristic, and the calculation unit calculates a time difference between the time change in the value indicating impedance that would be acquired in a state without static electricity and the time change in the value indicating impedance acquired by the measurement circuit. The values ​​of α, τ, and δ are obtained by fitting the following equations, where t is the supply time of pure water, α is a proportionality constant, τ is a time constant, and δ is a delay time.

6. An electrical characteristic measuring device according to claim 1, wherein a plurality of pairs of electrodes including the pair of electrodes are provided on the measurement substrate, and the plurality of pairs of electrodes are arranged at different positions in the radial direction of the measurement substrate.

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

8. A measurement substrate used to evaluate the amount of charge on an upper surface onto which a liquid is supplied while rotating, comprising: a plurality of pairs of electrodes provided on the upper surface; a plurality of wirings extending from the plurality of pairs of electrodes to the outer edge of the upper surface; and a plurality of connection points at the ends of the plurality of wirings at the outer edge, which are used for electrical connection to the outside.

9. A method for measuring electrical characteristics, comprising: a) a step of holding a measurement substrate having a pair of electrodes formed on its upper surface and rotating the measurement substrate around an axis perpendicular to the measurement substrate; b) a step of supplying a predetermined liquid onto the measurement substrate in parallel with the step a); and c) a step of acquiring a value indicating the electrical characteristics between the pair of electrodes in parallel with the step b) or after the step b).

10. The electrical characteristic measuring method according to claim 9, further comprising the step of: d) supplying an electrolyte onto the measurement substrate during the step a) prior to the step b).

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