Surface potential distribution measurement device

Abstract

This surface potential distribution measurement device comprises: a sensor board provided with a plurality of sensors; a vibration unit that vibrates the sensor board; an electrical characteristics measurement unit that uses each of the sensors to measure the electric potential of an object of measurement; a heating unit that heats the object of measurement; a temperature measurement unit that measures the temperatures of the sensor board and the object of measurement; and a control unit that controls the temperature of the sensor board. The control unit controls the temperature of the sensor board such that the time during which the temperature of the sensor board is at or above a threshold is a prescribed time or less.

Description

Surface potential distribution measurement device

[0001] The present invention relates to a surface potential distribution measuring device. This application claims priority based on Japanese Patent Application No. 2024-180231, filed in Japan on October 15, 2024, the contents of which are incorporated herein by reference.

[0002] Filters made from nonwoven fabrics such as polypropylene fibers are used in masks and air purifiers. To improve collection efficiency, the nonwoven fabrics used in filters are being electretized. An electret is a substance that maintains electrical polarization semi-permanently and forms an electrolytic layer around it.

[0003] Electretization is carried out by methods such as corona discharge and water flow charging. The state of the electret affects the collection efficiency. Furthermore, the charge trapping state of the electret affects its stability. For example, if the charge can be trapped in an energetically deep level during electretization, a more stable electret can be obtained. In this specification, the energy level at which the charge is trapped is referred to as the charge trapping state.

[0004] Patent Document 1 describes a technique for evaluating the charge state of an electret, comprising: a detection unit that moves continuously in a predetermined direction relative to the surface of a charged object to be measured; a reference distance measuring unit that measures the distance between the surface of the object to be measured and the surface of the detection unit; a distance adjustment unit that adjusts the distance between the surface of the object to be measured and the surface of the detection unit so that the distance measured by the reference distance measuring unit becomes a predetermined reference distance; a vibration unit that changes the distance between the surface of the object to be measured and the surface of the detection unit at a predetermined period; and a unit that measures at least one of the change in potential, frequency, and phase angle detected by the detection unit. A static electricity distribution measuring device is disclosed, comprising a measurement unit, a calculation unit that calculates the amount of static electricity on the surface of the object to be measured based on the relative movement distance of the object to be measured with respect to the detection unit and the measurement result of the measurement unit, wherein the surface of the detection unit is provided with a plurality of sensors that detect changes in potential caused by changing the distance from the surface of the object to be measured, and the vibration unit changes the range of change in the distance between the surface of the object to be measured and the surface of the detection unit according to the amount of static electricity on the surface of the object to be measured calculated by the calculation unit.

[0005] Furthermore, as a technique for evaluating the charge trapping state, Patent Document 2 discloses a thermal stimulation current measuring device comprising: a data acquisition unit that acquires correlation data showing the correlation between activation energy and temperature using measurement data obtained by measuring the thermal stimulation current of a sample; an extraction unit that extracts flat parts of the plot when the correlation between activation energy and temperature is graphed using the correlation data; an evaluation unit that evaluates the characteristics of the sample based on the extraction results of the extraction unit; and a display unit 6 that displays the evaluation results by the evaluation unit on a screen.

[0006] Japanese Patent No. 6797378, Japanese Patent Publication No. 2015-28462, Japanese Patent No. 5665151, International Publication No. 2015 / 011942

[0007] The method described in Patent Document 1 can evaluate the distribution of the surface potential of the object being measured, but it could not evaluate the in-plane distribution of the charge trap levels. The method described in Patent Document 2 can evaluate the averaged charge trap state by applying heat to the object being measured and measuring the emitted current, but it could not evaluate the in-plane distribution of the charge trap levels of the object being measured.

[0008] This invention was made in view of the above circumstances, and aims to provide a surface potential distribution measuring device capable of evaluating the surface potential distribution and the in-plane distribution of the trap state of a measurement target.

[0009] To solve the above problems, the present invention proposes the following means: (1) A surface potential distribution measuring device of embodiment 1 of the present invention comprises: a sensor substrate equipped with a plurality of sensors; a vibration unit that vibrates the sensor substrate; an electrical characteristic measuring unit that measures the potential of a target to be measured using each of the sensors; a heating unit that heats the target to be measured; a temperature measuring unit that measures the temperature of the sensor substrate and the temperature of the target to be measured; and a control unit that controls the temperature of the sensor substrate, wherein the control unit controls the temperature of the sensor substrate so that the time during which the temperature of the sensor substrate is above a threshold is less than or equal to a predetermined time. (2) A embodiment 2 of the present invention is a surface potential distribution measuring device of embodiment 1, further comprising a cooling unit that cools the sensor substrate, wherein the control unit controls the cooling unit so that the temperature of the sensor substrate is below a threshold. (3) Embodiment 3 of the present invention is a surface potential distribution measuring device of Embodiment 1 or Embodiment 2, wherein the sensor substrate comprises a substrate, a plurality of sensors provided on a first surface which is one surface of the substrate, and a plurality of conductive parts exposed on a second surface which is the opposite surface of the first surface and extending from each of the sensors in the thickness direction of the substrate, wherein the substrate is made of a heat-resistant material. (4) Embodiment 4 of the present invention is a surface potential distribution measuring device of any one of Embodiments 1 to 3, further comprising a vibration measuring unit for measuring the amplitude of the sensor substrate. (5) Embodiment 5 of the present invention is a surface potential distribution measuring device of any one of Embodiments 1 to 4, wherein each of the sensors is arranged in a straight line in a plan view. (6) Embodiment 6 of the present invention is a surface potential distribution measuring device according to any one of embodiments 1 to 5, further comprising: a sample stage on which the object to be measured can be placed; and a moving unit for moving the sample stage, wherein the sample stage and the moving unit are arranged at a distance from each other, the heating unit and the moving unit are connected via a support unit, and the support unit has a point contact structure.

[0010] According to each of the above embodiments of the present invention, a surface potential distribution measuring device capable of evaluating the surface potential distribution and the in-plane distribution of the charge trap state of a measurement target can be provided.

[0011] This is a schematic diagram of a surface potential distribution measuring device according to the first embodiment of the present invention. This is a plan view of the sensor-side surface of the sensor substrate. This is a cross-sectional view of the sensor substrate shown in Figure 2 along line A-A. This is a flowchart of the method for measuring the in-plane distribution of charge trap levels according to the first embodiment. This is a schematic diagram of a surface potential distribution measuring device according to the second embodiment of the present invention. This is a flowchart of the method for measuring the in-plane distribution of charge trap levels according to the second embodiment. This is a diagram showing the relationship between surface potential and sample temperature.

[0012] (First Embodiment) The surface potential distribution measuring device according to the first embodiment comprises a sensor substrate equipped with a plurality of sensors, a vibration unit that vibrates the sensor substrate, an electrical characteristic measuring unit that measures the potential of a target to be measured using each of the sensors, a heating unit that heats the target to be measured, a temperature measuring unit that measures the temperature of the sensor substrate and the temperature of the target to be measured, and a control unit that controls the temperature of the sensor substrate, wherein the control unit controls the temperature of the sensor substrate so that the time during which the temperature of the sensor substrate is above a threshold is less than or equal to a predetermined time. Furthermore, the sensors are provided on a first surface, which is one surface of the sensor substrate according to this embodiment, and on a second surface, which is the opposite surface of the first surface, a plurality of conductive parts extending in the thickness direction of the sensor substrate from each of the sensors are exposed, and each conductive part is insulated from each other.

[0013] Hereinafter, a surface potential distribution measuring device 100 according to the first embodiment of the present invention will be described with reference to the drawings. Figure 1 is a schematic diagram of the surface potential distribution measuring device 100. The surface potential distribution measuring device 100 comprises a sensor substrate 10, a holding part 20, a shaft 30, a vibration part 40, a vibration control unit 45, an electrical characteristic measurement unit 50, a temperature measurement unit 51, a cooling unit 80, a sample stage 60, a support part 63, a moving part 65, a heating unit 70, a vibration measurement unit 110, a distance measurement unit 120, and a control unit 130.

[0014] The amount of charge (surface potential) Q of the portion of the object to be measured O (measurement region) in the sensor substrate 10 facing the sensor is calculated, for example, based on the following equation (1). By evaluating the surface potential distribution of the measurement region in each temperature range when the object to be measured O is heated, the in-plane distribution of the charge trap state can be evaluated. Here, in equation (1), ΔV means the difference (potential difference) between the maximum potential and the minimum potential detected by the sensor on the sensor substrate 10, ε means the dielectric constant between the sensor on the sensor substrate 10 and the portion of the object to be measured O facing the sensor, S means the area of ​​the sensor, and D means the distance between the surface of the sensor and the surface of the object to be measured O along the thickness direction of the sensor substrate 10. R means the amplitude of vibration of the sensor substrate 10.

[0015]

[0016] By moving the object to be measured O in a predetermined direction and calculating the surface potential of each portion of the object to be measured O facing each sensor 12 of the sensor substrate 10 using the above equation (1), the surface potential distribution of the surface of the object to be measured O can finally be calculated. For the method of calculating the surface potential, for example, the methods described in Patent Documents 3 and 4 can be used.

[0017] The following describes each part. In the following description, the X direction is the direction parallel to the first surface 11a of the sensor substrate 10. The Y direction is the direction parallel to the first surface 11a of the sensor substrate 10 and intersects with the X direction. For example, the Y direction is approximately perpendicular to the X direction. The Z direction is the thickness direction of the substrate 11 of the sensor substrate 10 and intersects with the X and Y directions. For example, the Z direction is approximately perpendicular to the X and Y directions. The "downward direction in the Z direction" refers to the direction from the sensor substrate 10 toward the sample stage 60 along the Z direction. The "upward direction in the Z direction" refers to the direction opposite to the direction from the sensor substrate 10 toward the sample stage 60 along the Z direction. However, the terms "up" and "down" used herein are for explanatory convenience and do not define the direction of gravity.

[0018] (Sensor substrate 10) Figure 2 is a plan view of the sensor-side surface (first surface) of the sensor substrate 10. Figure 3 is a cross-sectional view of the sensor substrate 10 shown in Figure 2 along the line A-A. The sensor substrate 10 comprises a substrate 11, a plurality of sensors 12 provided on the first surface 11a, which is one surface of the substrate 11, and a plurality of conductive parts 14 exposed on the second surface 11b, which is the opposite surface of the first surface 11a, and extending from each sensor 12 in the thickness direction of the substrate 11. In this embodiment, the thickness direction of the substrate 11 is the same as the Z direction.

[0019] The substrate 11 has the function of insulating the conductive parts 14 from each other. The temperature of the substrate 11 rises due to radiant heat when the object to be measured O is heated in the heating unit 70. In this case, if the deformation of the substrate 11 exceeds 10 μm in the thickness direction, the measurement accuracy of the surface potential distribution decreases. For this reason, it is preferable that the substrate 11 be made of a heat-resistant material such that the amount of deformation of the substrate 11 in the thickness direction is 10 μm or less when the object to be measured O is heated (when measuring the charge trap state). For example, materials that can be used for the substrate 11 include resins such as polycarbonate, polyphenylene sulfide, polyetheretherketone, and Teflon (registered trademark), engineering plastics, fiber-reinforced resins such as glass fiber reinforced epoxy resin, and ceramics.

[0020] The coefficient of linear thermal expansion of the material used in the substrate 11 is 100 × 10⁻⁶. －６ It is preferable that the coefficient of thermal expansion is 25 × 10⁻¹⁰. －６ It is more preferable that the coefficient of thermal expansion of the material used for the substrate 11 is 5 × 10⁻⁶. －６ It may be 1 / K or higher. The coefficient of thermal expansion of the substrate 11 can be measured, for example, based on JIS K 7197:2012.

[0021] The substrate 11 may be provided with a plurality of through holes 18 for passing the fixing portion 22 through. It is preferable that there be two or more through holes. If there are two or more through holes (i.e., two or more fixing points), even if the sensor substrate 10 is vibrated during measurement, deformation of the substrate 11 is less likely to occur, so that the change in surface potential can be measured more precisely. In addition, by increasing the number of fixing points, bending deformation of the sensor substrate 10 due to heating of the object to be measured O can be further suppressed.

[0022] The sensor 12 is provided on the first surface 11a, which is one of the surfaces of the substrate 11. The sensor 12 is a sensor that detects changes in potential caused by changing the distance from the surface of the object to be measured O. Using the sensor 12, for example, the difference between the maximum potential and the minimum potential (potential difference) can be measured. Alternatively, the sensor 12 may be used to measure the periodic change in potential (potential frequency) caused by the periodic change in the distance between the charged part of the object to be measured O and the sensor 12. Furthermore, the sensor 12 may be used to detect the phase difference (potential phase difference) between the period of change in the relative distance between the charged part of the object to be measured O and the sensor 12 and the period of potential detected by the sensor 12.

[0023] The sensor 12 is not particularly limited as long as it can detect changes in potential. The temperature of the sensor 12 also rises due to radiant heat when the object to be measured O is heated in the heating unit 70. For this reason, it is preferable that the sensor 12 is made of a heat-resistant material such that the amount of deformation in the thickness direction when the object to be measured O is heated is 10 μm or less. For example, it is preferable that the sensor 12 is a thin film of a metal such as gold or copper.

[0024] The coefficient of linear thermal expansion of the material used in sensor 12 is 50 × 10 －６ It is preferable that the coefficient of linear expansion of the material used in the sensor 12 is 20 × 10 －６ It is more preferable that it be less than or equal to / K. The coefficient of linear expansion of the material used in the sensor 12 is 5 × 10 －６ It may be 1 / K or higher. The coefficient of linear expansion of sensor 12 can be measured, for example, based on JIS Z 2285:2003.

[0025] The shape of the sensor 12 is not particularly limited, but for example, it is square in a plan view. The sensors 12 are arranged at predetermined intervals. The length lx in the X direction of the sensor 12 is not particularly limited. For example, the length lx in the X direction of the sensor 12 is 0.1 mm to 10 mm. Similarly, the length ly in the Y direction of the sensor 12 is not particularly limited. For example, the length ly in the Y direction of the sensor 12 is 0.1 mm to 10 mm. The length lx in the X direction of the sensor 12, the length ly in the Y direction of the sensor 12, and the spacing between the sensors 12 can be appropriately set according to the desired resolution. By appropriately setting the distance between the sensor 12 and the object to be measured O (1 / 4 to 2 of the spacing between the sensors 12) and the vibration amplitude (1 / 8 to 1 of the spacing between the sensors 12), the spatial resolution can be arbitrarily determined.

[0026] Multiple sensors 12 are arranged in a straight line on the substrate 11 in a plan view. Here, the sensors 12 are arranged along a virtual line L1 parallel to the X direction. In this embodiment, it is preferable that the length ls of the arrangement of sensors 12 is longer than the length of the object to be measured O in the direction perpendicular to the direction in which the object to be measured O is moved (here, the Y direction) when measuring the potential. By arranging them in this way, the object to be measured O can be moved in only one direction (the Y direction) without moving the object to be measured O in the X direction. If the length ls of the arrangement of sensors 12 is shorter than the length of the object to be measured O in the direction perpendicular to the direction in which the object to be measured O is moved, the surface potential distribution can be measured over the entire surface area of ​​the side of the object to be measured O facing the sensors 12 by moving the object to be measured O in the X direction as well.

[0027] The sensor substrate 10 includes a plurality of conductive portions 14 that are exposed on the second surface 11b, which is the opposite surface of the first surface 11a, and extend in the thickness direction of the substrate 11 from each sensor 12. The conductive portions 14 are insulated from each other by the substrate 11, which is an insulator. In the present embodiment, the conductive portions 14 penetrate the substrate 11. In the first embodiment, the sensor 12 and the conductive portion 14 are electrically connected. The conductive portion 14 is not particularly limited as long as it is a material capable of transmitting the potential obtained by the sensor 12 to the electrical characteristic measurement unit 50. When the measurement object O is heated by the heating unit 70, the temperature of the conductive portion 14 also rises due to radiant heat or the like. Therefore, it is preferable that the conductive portion 14 is made of a heat-resistant material having a deformation amount in the thickness direction of 10 μm or less when the measurement object O is heated (when measuring the in-plane distribution of the charge trap state). The conductive portion 14 is preferably made of a metal such as copper, for example. The conductive portion 14 is electrically connected to the wiring 16.

[0028] The linear expansion coefficient of the material used for the conductive portion 14 is preferably 50×10 －６ / K or less. The linear expansion coefficient of the material used for the conductive portion 14 is more preferably 20×10 －６ / K or less. The linear expansion coefficient of the material used for the conductive portion 14 may be 5×10 －６ / K or more. The linear expansion coefficient of the conductive portion 14 can be measured, for example, based on JIS Z 2285:2003.

[0029] The sensor substrate 10 preferably includes a connection portion 15 that electrically connects the electrical characteristic measurement unit 50 and each conductive portion 14 to the second surface 11b in a detachable manner. The connection portion 15 is electrically connected to the wiring 16. The wiring 16 connects each conductive portion 14 and the connection portion 15. The connection portion 15 is, for example, a connector terminal. By providing the connection portion 15 that can be detachably connected, it is possible to change to a sensor substrate 10 suitable for the purpose.

[0030] (Holding portion 20) The holding portion 20 holds the sensor substrate 10. The holding portion 20 may hold the sensor substrate 10 in a detachable manner. The holding portion 20 includes a holding plate 21 and a fixing portion 22.

[0031] (Holding plate 21) The holding plate 21 is a plate for fixing the sensor substrate 10. The sensor substrate 10 is positioned so that the second surface 11b and the surface 21a of the holding plate 21 face each other, and the sensor substrate 10 and the holding plate 21 are fixed by the fixing part 22. In Figure 1, the holding plate 21 and the sensor substrate 10 are separated, but when heat is dissipated via the holding plate 21, it is preferable that the holding plate 21 and the sensor substrate 10 are in contact. When heat is dissipated via the holding plate 21, it is preferable that the holding plate 21 is made of a material with high thermal conductivity. The holding plate 21 has a thermal conductivity of 100 W・m －１ ・K －１ It is preferable that the sensor is made of the above-mentioned high thermal conductivity material. Examples of high thermal conductivity materials include aluminum and copper. The thermal conductivity of the high thermal conductivity material can be measured, for example, by a method in accordance with JIS R 1611:2010. If the retaining plate 21 is made of a conductive high thermal conductivity material, it is preferable that the wiring 16 of the sensor substrate 10 and the retaining plate 21 are insulated from each other.

[0032] The fixing part 22 is not particularly limited as long as it can transmit vibrations to the sensor substrate 10. For example, the fixing part 22 is a bolt and nut. In this embodiment, the fixing part 22 is passed through the through hole 18 of the substrate 11 and fixed. The sensor substrate 10 may be fixed in a detachable manner. Also, when heat is dissipated via the retaining plate 21, it is preferable that the fixing part 22 is also made of a material with high thermal conductivity. The fixing part 22 has a thermal conductivity of 100 W·m －１ ・K －１ It is preferable that the components be made of the above-mentioned high thermal conductivity materials. Examples of materials for the fixing part 22 include aluminum and copper.

[0033] (Shaft 30) The shaft 30 connects the holding plate 21 of the holding part 20 to the vibrating part 40. The shaft 30 is not particularly limited as long as it can hold the sensor substrate 10 and the holding part 20. The shaft 30 may be directly connected to the sensor substrate 10. If the shaft 30 is directly connected to the sensor substrate 10, the holding part 20 may not be necessary.

[0034] (Vibrating unit 40) The vibrating unit 40 vibrates the holding unit 20 and the sensor substrate 10 in a predetermined direction (for example, the thickness direction of the sensor substrate 10). When there is no holding unit 20, the vibrating unit 40 vibrates the sensor substrate 10 in a predetermined direction. In the present embodiment, the vibrating unit 40 vibrates the holding plate 21 and the sensor substrate 10 in the thickness direction of the sensor substrate 10 by vibrating the shaft 30. The vibrating unit 40 is not particularly limited as long as it can vibrate the sensor substrate 10 and the holding unit 20 at a predetermined cycle. The vibrating unit 40 is electrically connected to, for example, a vibration control unit 45. The vibrating unit 40 is controlled by the vibration control unit 45.

[0035] (Vibration control unit 45) The vibration control unit 45 controls the vibrating unit 40 so that the sensor substrate 10 vibrates under predetermined conditions. The cycle (frequency) at which the vibrating unit 40 vibrates the sensor substrate 10 and the holding unit 20 is not particularly limited. The cycle of the vibrating unit 40 is, for example, 10 Hz to 5 kHz. A more preferable cycle is in the range of 50 Hz to 1 kHz. The amplitude when the vibrating unit 40 vibrates the sensor substrate 10 and the holding unit 20 is not particularly limited. The amplitude of the vibrating unit 40 is, for example, 0.01 mm to 5 mm. A more preferable amplitude of the vibrating unit 40 is 0.05 mm to 0.5 mm. The vibration control unit 45 vibrates the sensor substrate 10 and the holding unit 20 based on, for example, a signal sent from the control unit 130.

[0036] Here, the amplitude of the vibration of the sensor substrate 10 will be described. In the above formula (1), when the charge amount Q, the dielectric constant ε, the area S of the sensor of the sensor substrate 10, and the distance D are constant, the detected potential difference ΔV can be calculated by the following formula (2). In formula (2), a and b are predetermined constants.

[0037]

[0038] As shown in the above formula (2), the potential difference ΔV detected by the sensor 12 is represented as a function only of the amplitude R of the sensor substrate 10. That is, as the amplitude R increases, the potential difference ΔV also increases. In the surface potential distribution measuring device 100, the surface potential of the measurement object O can be detected with high accuracy by adjusting (increasing) the amplitude R.

[0039] (Electrical characteristic measurement unit 50) The electrical characteristic measurement unit 50 measures the potential using each sensor 12. The electrical characteristic measurement unit 50 is, for example, an oscilloscope or a lock-in amplifier (not shown). Preferably, the electrical characteristic measurement unit 50 can remove noise and the like from the signal detected by the sensor 12 and simultaneously measure minute signals in multiple channels. The electrical characteristic measurement unit 50 is electrically connected to the control unit 130 and sends the potential information obtained by each sensor 12 to the control unit 130.

[0040] (Temperature measurement unit 51) The temperature measurement unit 51 measures the temperature of the sensor substrate 10 and the temperature of the measurement object O. As the temperature measurement unit 51, known means such as a thermocouple or thermography can be used. Thermography is preferable as the temperature measurement unit 51. By using thermography, the temperature distribution of the sensor substrate 10 and the temperature distribution of the measurement object O can be measured. By measuring the temperature distribution of the sensor substrate 10, the locations that require cooling can be specified. Also, by measuring the temperature distribution of the measurement object O, the distribution of the charge trap state can be evaluated more precisely. The measured temperature information of the sensor substrate 10 and the measurement object O is sent to the control unit 130.

[0041] (Sample stage 60) The sample stage 60 is a stage on which the measurement object O and the heating unit 70 can be arranged. In the present embodiment, the heating unit 70 is arranged on the sample stage 60. The measurement object O is arranged on the heating unit 70. The sample stage 60 is not particularly limited as long as it can arrange the measurement object O and the like.

[0042] (Moving unit 65) The moving unit 65 moves the sample stage 60 in a direction parallel to the first surface 11a. Also, the moving unit 65 adjusts the distance D between the surface of the measurement object O and the surface of the sensor 12 within a predetermined range. When a plurality of sensors 12 are arranged in a straight line in a plan view on the virtual line L1, the moving unit 65 preferably moves the sample stage 60 in a direction perpendicular to the virtual line L1. By moving in this way, the surface potential distribution of the measurement object O can be efficiently measured. The moving unit 65 can be moved in the X direction, Y direction, and Z direction by, for example, a motor. The moving unit 65 is controlled by the control unit 130.

[0043] The sample stage 60 and the movable unit 65 are positioned at a distance from each other. In this embodiment, the sample stage 60 and the movable unit 65 are positioned at a distance from each other in the Z direction. By arranging the sample stage 60 and the movable unit 65 in this way, the effect of heating on the movable unit 65 can be suppressed, and the accuracy of position control of the sample stage 60 by the movable unit 65 can be easily maintained. Insulating material may be used to reduce the effect of heat.

[0044] The sample stage 60 and the movable part 65 are connected via a support part 63. The support part 63 has a point contact structure 62. The support part 63 is not particularly limited as long as it connects the sample stage 60 and the movable part 65 and has a point contact structure 62. In this embodiment, the support part 63 has a shaft 61 connected to the sample stage 60 and a point contact structure 62 connected to the movable part 65. The point contact structure 62 only needs to be fixed to the shaft 61 at a distance from the heat source (heating part) 70. The further the position where the point contact structure 62 and the shaft 61 are fixed is from the heat source (heating part) 70, the lower the temperature will be due to natural cooling, and the more heat transfer can be suppressed. The fixing method is not particularly limited. Examples of fixing methods include magnets and screws. For example, the point contact structure 62 may be fixed by installing a magnet near its lower end. The point contact structure 62 is, for example, a ball bush. The point contact structure 62 is in point contact with the shaft 61. Therefore, heat transfer from the sample stage 60 to the moving part 65 can be suppressed. This makes it easier to maintain the accuracy of position control of the moving part 65.

[0045] (Heating Unit 70) The heating unit 70 heats the object to be measured O. The heating unit 70 heats the object to be measured O according to the control of the control unit 130. In this embodiment, the heating unit 70 is placed on the sample stage 60, but the heating unit 70 may also be placed inside the sample stage 60. In this embodiment, the object to be measured O is placed on the heating unit 70. The heating unit 70 is not particularly limited as long as it can heat the object to be measured O. For example, the heating unit 70 may be a ceramic heater or an infrared heater. It is preferable that the heating unit 70 can raise the temperature of the object to be measured O at a predetermined heating rate. The heating rate may be, for example, 0.5 K / min to 5 K / min.

[0046] (Cooling section 80) The cooling section 80 cools the sensor substrate 10. The cooling section 80 is, for example, a fan, a water cooling device, etc., and may be controlled by the control unit 130. By using the cooling section 80, the sensor substrate 10 can be cooled efficiently. When measuring the in-plane distribution of the charge trap state, it is preferable that the cooling section 80 cools the sensor substrate 10 but not the object to be measured O. If the object to be measured O is cooled by the cooling section 80, it becomes impossible to accurately determine at what temperature range the dielectric charge was released, and the accuracy of evaluating the in-plane distribution of the charge trap state decreases. It is preferable that the cooling section 80 does not cool the sensor substrate 10 when measuring the surface potential. If the sensor substrate 10 is cooled by the cooling section 80 when measuring the surface potential, it will affect the vibration of the sensor substrate 10 and the accuracy of surface potential measurement will decrease, so it is preferable to cool the sensor substrate 10 in a way that does not cause it to vibrate. Methods for cooling the sensor substrate 10 to prevent vibration include, for example, cooling the sensor substrate 10 after the measurement of the surface potential is completed, cooling the sensor substrate 10 by blowing air only on the shaft 30 on the back side of the sensor substrate 10 during the measurement of the surface potential, and cooling the sensor substrate with water by providing a flow path for a refrigerant (not shown) in the sensor substrate.

[0047] (Vibration Measurement Unit 110) The vibration measurement unit 110 measures the amplitude of the sensor substrate 10. The vibration measurement unit 110 is electrically connected to the control unit 130. The vibration measurement unit 110 is not particularly limited as long as it can measure the amplitude of the sensor substrate 10. For example, the vibration measurement unit 110 is a laser displacement sensor. The vibration measurement unit 110 sends the measured vibration information of the sensor substrate 10 to the control unit 130.

[0048] (Distance Measurement Unit 120) The distance measurement unit 120 measures the distance D between the surface of the sensor 12 and the surface of the object to be measured O. By measuring the positional relationship between the position of the distance measurement unit 120 and the surface of the sensor 12 in advance, the distance D between the surface of the sensor 12 and the surface of the object to be measured O can be measured. The distance measurement unit 120 is not particularly limited as long as it can measure the distance D between the surface of the sensor 12 and the surface of the object to be measured O. For example, the distance measurement unit 120 is a laser displacement sensor. The distance measurement unit 120 sends the measured distance D between the surface of the sensor 12 and the surface of the object to be measured O to the control unit 130.

[0049] (Control Unit 130) The control unit 130 moves the object to be measured O while vibrating the sensor substrate 10 and the holding unit 20 by controlling the vibration control unit 45 and the moving unit 65. Based on the distance D between the surface of the object to be measured O and the surface of the sensor 12 obtained by the distance measurement unit 120, the control unit 130 adjusts the position of the object to be measured O in the Z direction using the moving unit 65. Specifically, the position of the object to be measured O is adjusted so that the distance D is within the allowable range of the reference distance DS (DS ± α).

[0050] The control unit 130 controls the heating unit 70 to heat the object to be measured O at a predetermined heating rate. The control unit 130 also uses the electrical characteristics measurement unit 50 to measure the time change (potential information) of the potential of each sensor 12. In addition, the control unit 130 uses the temperature measurement unit 51 to measure the temperature distribution of the object to be measured O and the temperature of the sensor substrate 10.

[0051] The control unit 130 obtains vibration information of the sensor substrate 10 using the vibration measurement unit 110. The control unit 130 outputs the surface potential distribution and temperature distribution of the object to be measured O from the temperature distribution and potential information of the object to be measured O, the vibration information of the sensor substrate 10, and the amount of displacement information of the object to be measured O. The obtained surface potential distribution and temperature distribution of the object to be measured O are output to a storage unit (not shown) or a display unit (not shown). The surface potential distribution is, for example, a distribution drawn with varying shades of color so that the magnitude of the surface potential is visually easy to understand.

[0052] The control unit 130 controls the temperature of the sensor substrate 10 so that the time during which the temperature of the sensor substrate 10, as measured by the temperature measurement unit 51, is above a threshold (threshold temperature) is within a predetermined time (limit time). If the temperature of the sensor substrate 10 is measured with a thermocouple, it may be the temperature measured by the thermocouple. If the temperature of the sensor substrate 10 is measured with a thermograph, it may be the average value of the temperature distribution, or it may be the temperature at a predetermined location (for example, the location of the sensor 12).

[0053] The threshold temperature may be determined in advance by measuring the relationship between the temperature of the sensor substrate 10 and the amount of deformation of the sensor substrate 10. For example, the sensor substrate 10 may be heated (heated in the actual measurement configuration) under the heating conditions (heating rate, target temperature, etc.) of the object to be measured O when measuring the in-plane distribution of the trap state of the charge, and the temperature at which a region with a displacement of 10 μm in the thickness direction occurs may be set as the threshold temperature. The predetermined time may also be determined based on the measurement accuracy. For example, the predetermined time (limit time) may be the time at which the proportion of the region with a displacement of 10 μm in the thickness direction exceeds 10% of the total area of ​​the sensor substrate 10. The predetermined time (limit time) is, for example, 5 seconds. The time at which the threshold temperature is exceeded may be 0 seconds.

[0054] The control unit 130 controls the temperature of the sensor substrate 10, at least by controlling the moving unit 65, so that the time during which the temperature of the sensor substrate 10, as measured by the temperature measurement unit 51, exceeds a threshold is less than or equal to a predetermined time. The control unit 130 may further control the temperature of the sensor substrate 10, as measured by the temperature measurement unit 51, by controlling the cooling unit 80, so that the time during which the temperature of the sensor substrate 10, as measured by the temperature measurement unit 51, exceeds a threshold is less than or equal to a predetermined time. For example, if the time during which the temperature of the sensor substrate 10 exceeds a threshold exceeds a predetermined time, the control unit 130 controls the moving unit 65 to move the sensor substrate 10 a predetermined distance away from the heating unit 70. The predetermined distance is not particularly limited as long as it is a distance at which the temperature of the sensor substrate 10 does not rise. If the temperature of the sensor substrate 10 does not drop to a predetermined temperature (for example, room temperature) by the start time of surface potential measurement, the control unit 130 may control the cooling unit 80 to increase the cooling rate. The measurement start time can be set appropriately according to the heating time of the object to be measured O, etc.

[0055] The control unit 130 may consist of, for example, a Central Processing Unit (CPU), Read Only Memory (ROM), Random Access Memory (RAM), and a Hard Disk Drive (HDD) / Solid State Drive (SSD), etc. (not shown). In this case, the storage unit (not shown) will be an HDD or SSD. The display unit will be, for example, a liquid crystal display. The operation of the control unit 130 may be realized, for example, by executing a predetermined program in the CPU. The control unit 130 may also use a dedicated hardware configuration.

[0056] (Measurement target O) The measurement target O is not particularly limited as long as it has a charge distribution on its surface. Examples of the shape of the measurement target O include rectangular, cylindrical, and film-like shapes.

[0057] As described above, the surface potential distribution measuring device 100 according to this embodiment has been described in detail. Since the surface potential distribution measuring device 100 according to this embodiment is equipped with a plurality of sensors 12, the distribution of surface potential in the plane of the object to be measured can be quickly measured in a single measurement. In addition, the control unit 130 of the surface potential distribution measuring device 100 controls the temperature of the sensor substrate 10 so that the time during which the temperature of the sensor substrate 10 is above a threshold is less than or equal to a predetermined time. This makes it possible to evaluate the in-plane distribution of the charge trap state.

[0058] In the surface potential distribution measuring device 100, the sensor substrate 10 may be detachably held in the holding part 20. Alternatively, the sensor substrate 10 may be provided with a connecting part 15 that detachably connects the electrical characteristic measuring part 50 to each conductive part 14. This allows the sensor substrate 10 to be easily replaced depending on the purpose. Therefore, the resolution can be changed according to the application.

[0059] <Method for measuring the in-plane distribution of charge trap levels> Next, we will explain the method for measuring the in-plane distribution of charge trap levels of the object O to be measured using the surface potential distribution measuring device 100. Figure 4 is a flowchart of the method for measuring the in-plane distribution of charge trap levels.

[0060] The distance D between the surface of the object to be measured O and the surface of the sensor 12 is set to be within the allowable range of the reference distance DS, which is the measurable distance (S1). Specifically, if the distance D is within a predetermined value (allowable value) α (DS ± α) relative to the reference distance DS, the change in potential of the part of the object to be measured O facing the sensor 12 can be detected with high accuracy. The allowable value is, for example, 10% or less of the reference distance DS.

[0061] The distance measurement unit 120 is used to measure the distance D between the surface of the object to be measured O and the surface of the sensor 12. In this embodiment, the distance D between the surface of the object to be measured O and the surface of the sensor 12 is adjusted using the moving unit 65, by moving the object to be measured O to a predetermined position (S2, S3). If the distance D is not within a predetermined range (DS ± α), the moving unit 65 is used to adjust the distance D between the surface of the object to be measured O and the surface of the sensor 12 so that the distance D between the surface of the object to be measured O and the surface of the sensor 12 falls within the predetermined range.

[0062] Next, the vibration unit 40 is driven (ON) (S4). The amplitude R is measured by the vibration measurement unit 110, and the obtained amplitude R is transmitted to the control unit 130 (S5).

[0063] The change in potential of the portion of the object to be measured O facing the sensor 12 is measured for a predetermined time. Information on the change in potential of each sensor 12 is acquired by the electrical characteristics measurement unit 50. The acquired information on the change in potential of each sensor 12 is sent to the control unit 130 (S6). Subsequently, the object to be measured O is moved by a predetermined amount in the Y direction by the moving unit 65, and the distance moved (movement distance) is transmitted to the control unit 130 (S7). Here, the distance moved each time the object to be measured O moves can be freely determined according to the size of the sensor 12 and the required resolution of the surface potential distribution. Preferably, the movement distance is the same length as the length of the sensor 12 along the same direction as the movement direction Y of the object to be measured O (approximately 0.1 mm to 10 mm). By using such a movement distance, the surface potential distribution of the object to be measured O can be measured more accurately and quickly. If the measurement of the change in potential has not been completed for the entire surface area of ​​the side of the object to be measured O facing the sensor 12 (S8NO), the object to be measured O is moved again by a predetermined amount in the X or Y direction, and the measurement of the change in surface potential is continued (S7).

[0064] If the measurement of the change in potential has been completed for the entire surface area of ​​the surface of the object to be measured O facing the sensor 12 (S8 YES), the control unit 130 calculates the surface potential distribution of the object to be measured O from the information on the change in potential transmitted from the electrical characteristics measurement unit 50, the distance the object to be measured O moves per cycle, the number of times the object to be measured O moves, the amplitude R, and the reference distance (S9). The calculated surface potential distribution of the object to be measured O is then stored in a memory unit (not shown) or displayed on a display unit (not shown).

[0065] Specifically, a database consisting of numerous data points related to potential changes, reference distances, amplitudes, and corresponding surface potentials is calibrated and created in advance. The surface potential is then calculated from the amount of potential change, reference distance, and amplitude R obtained from each sensor 12. This surface potential represents the surface potential of the portion of the object to be measured O facing the sensor 12 when a potential change is detected.

[0066] Therefore, by pre-measuring the relative position of each sensor 12 with respect to the object O to be measured, the surface potential distribution of the object O can be measured quickly and with high accuracy using information on potential changes obtained from each sensor 12 (e.g., amount of potential change, frequency, phase shift), the distance the object O moves per measurement, the number of times the object O moves, the amplitude R, and the reference distance.

[0067] After calculating the surface potential distribution, the temperature measurement unit 51 is used to measure the temperature or temperature distribution of the object to be measured O. If the object to be measured O is not within the measurement range of the temperature measurement unit 51, the sensor substrate 10 may be moved away from the object to be measured O for measurement. The temperature or temperature distribution of the object to be measured O is recorded in a storage unit (not shown) or displayed on a display unit (not shown). The object to be measured O is heated by the heating unit 70 (S11). At this time, while measuring the surface potential distribution of the object to be measured, heating is performed while increasing the temperature at a rate that does not significantly change the surface potential distribution. Note that heating may also be performed while increasing the temperature at the set rate during potential distribution measurement, or the potential distribution may be measured while maintaining a constant temperature once the set temperature is reached.

[0068] After heating begins, the temperature of the sensor substrate 10 is measured (S12). After measuring the temperature of the sensor substrate 10, the change in potential of the portion of the object to be measured O facing the sensor 12 is measured for a predetermined time. Information on the change in potential of each sensor 12 is acquired by the electrical characteristics measurement unit 50. The acquired information on the change in potential of each sensor 12 is sent to the control unit 130 (S13). Subsequently, the object to be measured O is moved by a predetermined amount in the Y direction by the moving unit 65, and the distance moved (travel distance) is transmitted to the control unit 130 (S14). If, during potential measurement, the time for which the temperature of the sensor substrate 10 is above a threshold exceeds a predetermined time (S15 YES), the control unit 130 uses the moving unit 65 to move the sensor substrate 10 away from the object to be measured O. After moving the sensor substrate 10 away, the temperature of the object to be measured O is measured using the temperature measurement unit 51. If a sufficient cooling rate cannot be obtained by natural cooling, the control unit 130 controls the cooling unit 80 to cool the sensor substrate 10. When the temperature of the sensor substrate 10 drops to, for example, a certain set temperature (room temperature + 20°C), the sensor substrate 10 is returned to the position it was in before being separated from the object to be measured O (S16). If the time during potential measurement when the temperature of the sensor substrate 10 is above a threshold does not exceed a predetermined time (S15NO), the measurement of the change in surface potential is continued. The room temperature is, for example, 20°C to 30°C.

[0069] If the measurement of the change in potential has been completed for the entire surface area of ​​the surface of the object to be measured O facing the sensor 12 (S17 YES), the control unit 130 calculates the surface potential distribution of the object to be measured O from the information on the change in potential transmitted from the electrical characteristics measurement unit 50, the distance the object to be measured O moves per cycle, the number of times the object to be measured O moves, the amplitude R, and the reference distance (S18). The calculated surface potential distribution of the object to be measured O is then stored in a memory unit (not shown) or displayed on a display unit (not shown).

[0070] After calculating the surface potential distribution, the temperature measurement unit 51 is used to measure the temperature or temperature distribution of the object O. The temperature or temperature distribution of the object O is recorded in a storage unit (not shown) or displayed on a display unit (not shown).

[0071] If the measurement of the change in potential has not been completed for the entire surface area of ​​the surface of the object O facing the sensor 12 of the object O (S17NO), the object O is moved again by a predetermined amount in the X or Y direction, and the measurement of the change in surface potential is continued (S14).

[0072] After calculating the surface potential distribution, if the temperature of the object O has reached the set value (S19 YES), the measurement of the in-plane distribution of charge trap levels is terminated. If the temperature of the object O has not reached the set value (S19 NO), the object is moved a predetermined amount back to the initial potential measurement position, and the surface potential is measured again (S14).

[0073] As described above, the method for measuring the in-plane distribution of charge trap levels and the method for controlling the displacement amount according to this embodiment have been detailed. The method for measuring the in-plane distribution of charge trap levels according to this embodiment measures using multiple sensors while heating the object to be measured, so it is possible to measure the in-plane distribution of charge trap levels in the plane of the object to be measured O. Furthermore, the control unit 130 according to this embodiment controls the temperature of the sensor substrate 10 so that the time during which the temperature of the sensor substrate 10 is above a threshold is within a predetermined time, so the amount of deformation due to heating of the sensor substrate 10 can be suppressed, and the in-plane distribution of charge trap levels can be measured with high accuracy.

[0074] In this embodiment, the measurement was performed by moving the sample stage 60 in a direction parallel to the first surface 11a using the moving unit 65. However, the measurement may also be performed by moving the vibrating unit 40 in a direction parallel to the first surface 11a using a vibrating unit moving unit (not shown).

[0075] In this embodiment, after setting the distance D between the measurement target O and the surface of the sensor 12 in S1, the vibration start S4 of the vibration unit 40 and the vibration measurement S5 of the vibration unit 40 were performed. However, the distance D between the measurement target O and the surface of the sensor 12 in S1 may be set after the vibration start S4 and vibration measurement S5 of the vibration unit 40 have been performed.

[0076] In this embodiment, after adjusting the distance between the object to be measured O and the sensor 12 S3 and measuring the potential change S6, the object to be measured O is moved by a predetermined amount (S7). However, after moving the object to be measured O by a predetermined amount (S7), the adjustment of the distance between the object to be measured O and the sensor 12 S3 and the measurement of the potential change S6 may be performed. If the object to be measured O is flat, the distance adjustment S3 may be omitted.

[0077] Furthermore, when the vibration measurement unit 110 is used, the amplitude of the sensor substrate 10 is measured directly, allowing for the calculation of the surface potential distribution of the object O with greater accuracy. Also, when the distance measurement unit 120 is used, the distance D between the surface of the object O and the surface of the sensor 12 is adjusted, allowing for the calculation of the surface potential distribution of the object O with greater accuracy.

[0078] In this embodiment, the control unit 130 controlled the temperature of the sensor substrate 10 so that the time during which the temperature of the sensor substrate 10 was above a threshold was less than or equal to a predetermined time. That is, if the time during which the temperature of the sensor substrate was above the threshold temperature exceeded the limit time during surface potential distribution measurement, the sensor substrate 10 was cooled, but the present invention is not limited to this. The relationship between the heating rate of the object to be measured O and the sensor substrate 10 may be investigated in advance, and the heating rate of the object to be measured O may be controlled so that the surface potential distribution image of the object to be measured O can be measured without a cooling step for the sensor substrate 10. By controlling the heating rate in this way, the temperature of the sensor substrate 10 can be controlled so that the time during which the temperature of the sensor substrate 10 is above a threshold is less than or equal to a predetermined time.

[0079] Next, with reference to Figure 5, a surface potential distribution measuring device 100A according to a second embodiment of the present invention will be described. In this second embodiment, the same reference numerals are used for parts that are the same as those in the first embodiment, and their descriptions may be omitted. Figure 5 is a schematic diagram of the surface potential distribution measuring device 100A. The surface potential distribution measuring device 100 comprises a sensor substrate 10, a holding part 20, a shaft 30, a vibration part 40, a vibration control unit 45, an electrical characteristic measurement unit 50, a temperature measurement unit 51, a cooling unit 80, a sample stage 60, a support part 63, a moving part 65, a heating unit 70, a vibration measurement unit 110, a distance measurement unit 120, and a control unit 130A.

[0080] (Control Unit 130A) The control unit 130A moves the object to be measured O while vibrating the sensor substrate 10 and the holding unit 20 by controlling the vibration control unit 45 and the moving unit 65. Based on the distance D between the surface of the object to be measured O and the surface of the sensor 12 obtained by the distance measurement unit 120, the control unit 130A adjusts the position of the object to be measured O in the Z direction using the moving unit 65. Specifically, the position of the object to be measured O is adjusted so that the distance D is within the allowable range of the reference distance DS (DS ± α).

[0081] The control unit 130A controls the heating unit 70 to heat the object to be measured O at a predetermined heating rate. The control unit 130A also uses the electrical characteristics measurement unit 50 to measure the time change (potential information) of the potential of each sensor 12. In addition, the control unit 130A uses the temperature measurement unit 51 to measure the temperature distribution of the object to be measured O and the temperature of the sensor substrate 10.

[0082] The control unit 130A obtains vibration information of the sensor substrate 10 using the vibration measurement unit 110. The control unit 130A outputs the surface potential distribution and temperature distribution of the measurement target O from the temperature distribution and potential information of the measurement target O, the vibration information of the sensor substrate 10, and the amount of displacement information of the measurement target O. The obtained surface potential distribution and temperature distribution of the measurement target O are output to a storage unit (not shown) or a display unit (not shown).

[0083] The control unit 130A controls the temperature of the sensor substrate 10 so that the time during which the temperature of the sensor substrate 10, as measured by the temperature measurement unit 51, is above a threshold (threshold temperature) is within a predetermined time (limit time). In the second embodiment, the control unit 130A controls the cooling unit 80 so that the temperature of the sensor substrate 10 is below the threshold. By controlling the cooling unit 80 so that the temperature of the sensor substrate 10 is below the threshold, the time during which the temperature of the sensor substrate 10 is above the threshold can be kept within a predetermined time. In the second embodiment, since the control is made to keep the temperature below the threshold, the time during which the temperature is above the threshold is approximately 0 to 5 seconds. When the temperature of the sensor substrate 10 is measured with a thermocouple, it may be the temperature measured by the thermocouple. When the temperature of the sensor substrate 10 is measured with a thermograph, it may be the average value of the temperature distribution, or it may be the temperature at a predetermined location (for example, the location of the sensor 12).

[0084] The threshold temperature may be determined in advance by measuring the relationship between the temperature of the sensor substrate 10 and the amount of deformation of the sensor substrate 10. For example, the sensor substrate 10 may be heated (heated in the actual measurement configuration) under the heating conditions (heating rate, target temperature, etc.) of the object to be measured O when measuring the in-plane distribution of the charge trap state, and the temperature at which a region with a displacement of 10 μm in the thickness direction occurs may be set as the threshold temperature. The predetermined time may also be determined based on the measurement accuracy.

[0085] The control unit 130A controls the cooling unit 80 so that the temperature of the sensor substrate 10, as measured by the temperature measurement unit 51, falls below a threshold. For example, if the temperature of the sensor substrate 10 exceeds the threshold, the control unit 130A controls the cooling unit 80 to cool the sensor substrate 10 so that its temperature falls below the threshold.

[0086] The control unit 130A may consist of, for example, a Central Processing Unit (CPU), Read Only Memory (ROM), Random Access Memory (RAM), and a Hard Disk Drive (HDD) / Solid State Drive (SSD), etc. (not shown). In this case, the storage unit (not shown) will be an HDD or SSD. The display unit will be, for example, a liquid crystal display. The operation of the control unit 130A may be realized, for example, by executing a predetermined program in the CPU. The control unit 130A may also use a dedicated hardware configuration.

[0087] As described above, the surface potential distribution measuring device 100A according to this embodiment has been described in detail. Since the surface potential distribution measuring device 100 according to this embodiment is equipped with a plurality of sensors 12, the distribution of surface potential in the plane of the object to be measured can be quickly measured in a single measurement. In addition, the control unit 130A of the surface potential distribution measuring device 100 controls the cooling unit 80 so that the temperature of the sensor substrate 10 is below a threshold. This makes it possible to evaluate the in-plane distribution of the charge trap state.

[0088] <Method for measuring the in-plane distribution of charge trap levels> Next, a method for measuring the in-plane distribution of charge trap levels of a measurement target O using the surface potential distribution measuring device 100A according to the second embodiment will be described. Figure 6 is a flowchart of the method for measuring the in-plane distribution of charge trap levels.

[0089] The distance D between the surface of the object to be measured O and the surface of the sensor 12 is set to be within the allowable range of the reference distance DS, which is the measurable distance (S1). Specifically, if the distance D is within a predetermined value (allowable value) α (DS ± α) relative to the reference distance DS, the change in potential of the part of the object to be measured O facing the sensor 12 can be detected with high accuracy. The allowable value is, for example, 10% or less of the reference distance DS.

[0090] The distance measurement unit 120 is used to measure the distance D between the surface of the object to be measured O and the surface of the sensor 12. In this embodiment, the distance D between the surface of the object to be measured O and the surface of the sensor 12 is adjusted using the moving unit 65, by moving the object to be measured O to a predetermined position (S2, S3). If the distance D is not within a predetermined range (DS ± α), the moving unit 65 is used to adjust the distance D between the surface of the object to be measured O and the surface of the sensor 12 so that the distance D between the surface of the object to be measured O and the surface of the sensor 12 falls within the predetermined range.

[0091] Next, the vibration unit 40 is driven (ON) (S4). The amplitude R is measured by the vibration measurement unit 110, and the obtained amplitude R is transmitted to the control unit 130A (S5).

[0092] The change in potential of the portion of the object to be measured O facing the sensor 12 is measured for a predetermined time. Information on the change in potential of each sensor 12 is acquired by the electrical characteristics measurement unit 50. The acquired information on the change in potential of each sensor 12 is sent to the control unit 130A (S6). Subsequently, the object to be measured O is moved by a predetermined amount in the Y direction by the moving unit 65, and the distance moved (movement distance) is transmitted to the control unit 130A (S7). Here, the distance moved each time the object to be measured O moves can be freely determined according to the size of the sensor 12 and the required resolution of the surface potential distribution. Preferably, the movement distance is the same length as the length of the sensor 12 along the same direction as the movement direction Y of the object to be measured O (approximately 0.1 mm to 10 mm). By using such a movement distance, the surface potential distribution of the object to be measured O can be measured more accurately and quickly. If the measurement of the change in potential has not been completed for the entire surface area of ​​the side of the object to be measured O facing the sensor 12 (S8NO), the object to be measured O is moved again by a predetermined amount in the X or Y direction, and the measurement of the change in surface potential is continued. (S7).

[0093] If the measurement of the potential change has been completed for the entire surface area of ​​the surface of the object to be measured O facing the sensor 12 (S8 YES), the control unit 130A calculates the surface potential distribution of the object to be measured O from the potential change information transmitted from the electrical characteristic measurement unit 50, the distance the object to be measured O moves per cycle, the number of times the object to be measured O moves, the amplitude R, and the reference distance (S9). The calculated surface potential distribution of the object to be measured O is then stored in a memory unit (not shown) or displayed on a display unit (not shown).

[0094] Specifically, a database consisting of numerous data points related to potential changes, reference distances, amplitudes, and corresponding surface potentials is calibrated and created in advance. The surface potential is then calculated from the amount of potential change, reference distance, and amplitude R obtained from each sensor 12. This surface potential represents the surface potential of the portion of the object to be measured O facing the sensor 12 when a potential change is detected.

[0095] Therefore, by pre-measuring the relative position of each sensor 12 with respect to the object O to be measured, the surface potential distribution of the object O can be measured quickly and with high accuracy using information on potential changes obtained from each sensor 12 (e.g., amount of potential change, frequency, phase shift), the distance the object O moves per measurement, the number of times the object O moves, the amplitude R, and the reference distance.

[0096] After calculating the surface potential distribution, the temperature measurement unit 51 is used to measure the temperature or temperature distribution of the object to be measured O. If the object to be measured O is not within the measurement range of the temperature measurement unit 51, the sensor substrate 10 may be moved away from the object to be measured O for measurement. The temperature or temperature distribution of the object to be measured O is recorded in a storage unit (not shown) or displayed on a display unit (not shown). The object to be measured O is heated by the heating unit 70 (S11). At this time, while measuring the surface potential distribution of the object to be measured, heating is performed while increasing the temperature at a rate that does not significantly change the surface potential distribution. Note that heating may also be performed while increasing the temperature at the set rate during potential distribution measurement, or the potential distribution may be measured while maintaining a constant temperature once the set temperature is reached.

[0097] After heating begins, the temperature of the sensor substrate 10 is measured (S12). After measuring the temperature of the sensor substrate 10, the change in potential of the portion of the object to be measured O facing the sensor 12 is measured for a predetermined time. Information on the change in potential of each sensor 12 is acquired by the electrical characteristics measurement unit 50. The acquired information on the change in potential of each sensor 12 is sent to the control unit 130A (S13). Subsequently, the object to be measured O is moved by a predetermined amount in the Y direction by the moving unit 65, and the distance moved (movement distance) is transmitted to the control unit 130A (S14). If the temperature of the sensor substrate 10 exceeds a threshold during potential measurement (S15AYES), the control unit 130A cools the sensor substrate 10 using the cooling unit 80 (S16A) and returns to the temperature determination S15A of the sensor substrate 10. If the temperature of the sensor substrate 10 is below the threshold (S15ANO), measurement of the change in surface potential continues.

[0098] If the measurement of the change in potential has been completed for the entire surface area of ​​the surface of the object to be measured O facing the sensor 12 (S17 YES), the control unit 130A calculates the surface potential distribution of the object to be measured O from the information on the change in potential transmitted from the electrical characteristics measurement unit 50, the distance the object to be measured O moves per cycle, the number of times the object to be measured O moves, the amplitude R, and the reference distance (S18). The calculated surface potential distribution of the object to be measured O is then stored in a memory unit (not shown) or displayed on a display unit (not shown).

[0099] After calculating the surface potential distribution, the temperature measurement unit 51 is used to measure the temperature or temperature distribution of the object O. The temperature or temperature distribution of the object O is recorded in a storage unit (not shown) or displayed on a display unit (not shown).

[0100] If the measurement of the change in potential has not been completed for the entire surface area of ​​the surface of the object O facing the sensor 12 of the object O (S17NO), the object O is moved again by a predetermined amount in the X or Y direction, and the measurement of the change in surface potential is continued (S14).

[0101] After calculating the surface potential distribution, if the temperature of the object O has reached the set value (S19 YES), the measurement of the in-plane distribution of charge trap levels is terminated. If the temperature of the object O has not reached the set value (S19 NO), the object is moved a predetermined amount back to the initial potential measurement position, and the surface potential is measured again (S14).

[0102] As described above, the method for measuring the in-plane distribution of charge trap levels and the method for controlling the displacement amount according to the second embodiment have been described in detail. The method for measuring the in-plane distribution of charge trap levels according to this embodiment uses multiple sensors while heating the object to be measured, so it is possible to measure the in-plane distribution of charge trap levels in the plane of the object to be measured O. Furthermore, the control unit 130A according to this embodiment controls the cooling unit 80 so that the temperature of the sensor substrate 10 is below a threshold, so the amount of deformation due to heating of the sensor substrate 10 can be suppressed, and the in-plane distribution of charge trap levels can be measured with high accuracy.

[0103] Although the surface potential distribution measuring device according to this embodiment has been described above, the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. Furthermore, it is possible to replace the components in the above-described embodiment with well-known components without departing from the spirit of the invention.

[0104] Next, embodiments of the present invention will be described. The conditions in the embodiments are merely examples of conditions adopted to confirm the feasibility and effectiveness of the present invention, and the present invention is not limited to these examples of conditions. The present invention can adopt various conditions as long as they do not depart from the spirit of the invention and achieve the objectives of the present invention.

[0105] In the surface potential distribution measuring device 100 shown in Figure 1, the surface potential of a sample was evaluated using a sensor with a heat resistance temperature of 80°C or less. A metal sample to which a DC voltage was applied was placed on a heat plate. The temperature of the sample was raised on the heat plate, and the temperature of the sample surface was measured with an infrared camera. When the temperature of the sample reached the set temperature, the sensor was moved onto the heat plate, the surface potential was measured, and after the measurement was completed, the sensor was moved off the heat plate. The measurement time was set so that the sensor temperature would remain below 80°C. The obtained results are shown in Figure 7. In Figure 7, the horizontal axis represents the surface temperature of the sample (°C), and the vertical axis represents the surface potential (V). As shown in Figure 7, when using the surface potential distribution measuring device 100 according to this embodiment, the surface potential could be measured without sensor failure in the range of 50 to 170°C. On the other hand, when measurement was performed without sensor temperature control, the sensor temperature exceeded 110°C, making it impossible to evaluate the surface potential.

[0106] The surface potential distribution measuring device disclosed herein has high industrial applicability because it can evaluate the distribution of surface potential and the charge trapping state of the object being measured.

[0107] 10 Sensor substrate, 20 Holding unit, 30 Shaft vibration unit, 45 Vibration control unit, 50 Electrical characteristic measurement unit, 51 Temperature measurement unit, 52 Surface shape measurement unit, 60 Sample stage, 63 Support unit, 65 Moving unit, 70 Heating unit, 80 Cooling unit, 110 Vibration measurement unit, 120 Distance measurement unit, 130 Control unit

Claims

1. A surface potential distribution measuring device comprising: a sensor substrate equipped with multiple sensors; a vibration unit for vibrating the sensor substrate; an electrical characteristic measurement unit for measuring the potential of a target to be measured using each of the sensors; a heating unit for heating the target to be measured; a temperature measurement unit for measuring the temperature of the sensor substrate and the temperature of the target to be measured; and a control unit for controlling the temperature of the sensor substrate, wherein the control unit controls the temperature of the sensor substrate so that the time during which the temperature of the sensor substrate is above a threshold is less than or equal to a predetermined time.

2. The surface potential distribution measuring device according to claim 1, further comprising a cooling unit for cooling the sensor substrate, wherein the control unit controls the cooling unit so that the temperature of the sensor substrate falls below a threshold.

3. The surface potential distribution measuring device according to claim 1 or 2, wherein the sensor substrate comprises a substrate, a plurality of sensors provided on a first surface which is one surface of the substrate, and a plurality of conductive portions exposed on a second surface which is the opposite surface of the first surface and extending from each of the sensors in the thickness direction of the substrate, and the substrate is made of a heat-resistant material.

4. The surface potential distribution measuring device according to claim 1 or claim 2, further comprising a vibration measuring unit for measuring the amplitude of the sensor substrate.

5. The surface potential distribution measuring device according to claim 1 or claim 2, wherein each of the sensors is arranged in a straight line in a plan view.

6. The surface potential distribution measuring device according to claim 1 or 2, further comprising: a sample stage on which the object to be measured can be placed; and a moving unit for moving the sample stage, wherein the sample stage and the moving unit are arranged at a distance from each other; the heating unit and the moving unit are connected via a support unit; and the support unit has a point contact structure.

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