Contact type surface topography measuring device

Abstract

The utility model discloses a contact type surface topography measuring device which comprises a test board and a measuring module. In the measuring module, a probe is mechanically connected with a pressure applying assembly, a probe head of the probe is perpendicular to a placement plane of the test board, and the pressure applying assembly provides pressure for the probe to press the placement plane, so that the probe head of the probe is kept in contact with the surface of the wafer to be tested; the capacitive sensor is mechanically connected with the probe, the capacitive sensor can sample the movement displacement of the probe in a first direction, and the first direction is a direction perpendicular to the placement plane; the pressure control unit is respectively connected with the capacitive sensor and the pressure applying assembly, and correspondingly adjusts the pressure provided by the pressure applying assembly for the probe according to the sampling result of the motion displacement, thereby achieving the dynamic adjustment of the pressure of the probe, enabling the pressure of the probe to adapt to the motion displacement of the probe, preventing the damage of a device caused by the projection of a detected surface, and improving the detection precision. And the risk that the probe scratches the detected surface is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to surface topography measurement field especially relates to a contact type surface topography measurement device. BACKGROUND

[0002] With the development level of industrial automation and semiconductor equipment field is unceasing promotion, the object surface flatness and topography detection precision requirement is higher and higher, the traditional manual measurement method has been difficult to satisfy people's pursuit to high precision measurement.

[0003] In order to obtain higher precision measurement result, contact type measurement is applied more and more widely.Contact type measurement is through probe to the object surface contact type scanning, finally the scanned position signal is converted into electric signal through displacement sensor into the back end processing, and the interface display is completed in host computer.

[0004] However, by the current measurement mode, the probe increases the pressure between the probe and the measured object when encountering the surface protrusion in the sliding process, although the force is small, but the measurement of more than conventional pressure, can greatly increase the risk of probe scratching the measured surface. SUMMARY

[0005] The utility model provides a kind of contact type surface topography measurement device to reduce the risk of probe scratching the measured surface.

[0006] The present application provides a kind of contact type surface topography measurement device, contact type surface topography measurement device includes test table and measurement module;

[0007] The test table is used to place the wafer to be measured;

[0008] The measurement module includes probe, pressure applying assembly, capacitive sensor and pressure control unit;The probe is mechanically connected with the pressure applying assembly, the needle of the probe is vertically arranged with the placement plane of the test table, the pressure applying assembly provides pressure to the probe towards the placement plane, so that the needle of the probe keeps contact with the surface of the wafer to be measured;The capacitive sensor is mechanically connected with the probe, and the capacitive sensor can sample the movement displacement of the probe in the first direction, wherein the first direction is perpendicular to the placement plane;The pressure control unit is electrically connected with the capacitive sensor and the pressure applying assembly respectively, and the pressure control unit adjusts the pressure provided by the pressure applying assembly to the probe according to the sampling result of the movement displacement.

[0009] Optionally, the pressure applying assembly includes an electromagnetic coil and a metal pressure applying piece, the metal pressure applying piece is sleeved in the electromagnetic coil and mechanically connected with the probe;Two ends of the electromagnetic coil are connected with the pressure control unit.

[0010] Optionally, the pressure control unit comprises a controller, a voltage stabilizing chip and a digital-to-analog conversion chip.

[0011] The controller is electrically connected with the capacitive sensor, and the controller is further in communication connection with an input end of the digital-to-analog conversion chip, and the controller generates a pressure control signal according to a sampling result of the motion displacement;

[0012] A power supply end of the digital-to-analog conversion chip is electrically connected with an output end of the voltage stabilizing chip, and an output end of the digital-to-analog conversion chip is electrically connected with the electromagnetic coil, and the digital-to-analog conversion chip adjusts a current flowing through the electromagnetic coil according to the pressure control signal.

[0013] Optionally, the pressure control unit further comprises an operational amplifier circuit.

[0014] The operational amplifier circuit is arranged between the output end of the digital-to-analog conversion chip and the electromagnetic coil.

[0015] Optionally, the operational amplifier circuit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first capacitor, a first operational amplifier and a second operational amplifier.

[0016] A first input end of the first operational amplifier is electrically connected with the output end of the digital-to-analog conversion chip through the first resistor and is grounded through the second resistor; an output end of the first operational amplifier is electrically connected with a first input end of the second operational amplifier through the third resistor and is electrically connected with a second input end of the first operational amplifier.

[0017] A first input end of the second operational amplifier is grounded through the fourth resistor; a second input end of the second operational amplifier is electrically connected with the output end of the first operational amplifier in sequence through the fifth resistor and the sixth resistor; an output end of the second operational amplifier is electrically connected with the second input end of the second operational amplifier through the first capacitor; a connection point of the fifth resistor and the sixth resistor serves as a first total output end of the operational amplifier circuit, and the output end of the second operational amplifier serves as a second total output end of the operational amplifier circuit, and the first total output end and the second total output end are used for connecting the electromagnetic coil.

[0018] Optionally, the pressure control unit further comprises a precision resistor, and the precision resistor is connected in series with the electromagnetic coil.

[0019] Optionally, the pressure control unit further comprises a second capacitor and a third capacitor.

[0020] An input end of the voltage stabilizing chip is grounded through the second capacitor; and an output end of the voltage stabilizing chip is grounded through the third capacitor.

[0021] Optionally, the controller comprises a host computer or a micro control chip.

[0022] Optionally, the capacitive sensor is a differential capacitive sensor.

[0023] Optionally, the capacitive sensor is a single capacitive sensor.

[0024] The contact type surface topography measuring device provided by the utility model comprises a test table and a measuring module. The test table is used for placing a wafer to be measured. The measuring module comprises a probe, a pressure applying assembly, a capacitive sensor and a pressure control unit. The probe is mechanically connected with the pressure applying assembly. The needle of the probe is arranged perpendicularly to the placement plane of the test table. The pressure applying assembly provides pressure to the probe in the direction of the placement plane, so that the needle of the probe keeps in contact with the surface of the wafer to be measured. The capacitive sensor is mechanically connected with the probe. The capacitive sensor can sample the movement displacement of the probe in the first direction. The first direction is perpendicular to the placement plane. The pressure control unit is connected with the capacitive sensor and the pressure applying assembly respectively. According to the sampling result of the movement displacement, the pressure control unit adjusts the pressure provided by the pressure applying assembly to the probe, so that the dynamic adjustment of the probe pressure is realized. The probe pressure is adapted to the movement displacement, so that the damage of the device caused by the protrusion of the measured surface is prevented, and the risk of scratching the measured surface by the probe is reduced.

[0025] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the utility model, and is not used to limit the scope of the utility model. Other features of the utility model will become easy to understand through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical scheme in the embodiments of the utility model, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the utility model. For those skilled in the art, other drawings can also be obtained according to these drawings without creating labor.

[0027] Figure 1 The composition schematic diagram of the contact type surface topography measuring device provided by the utility model embodiment is shown in the figure.

[0028] Figure 2 The composition schematic diagram of another contact type surface topography measuring device provided by the utility model embodiment is shown in the figure.

[0029] Figure 3 The structure schematic diagram of the capacitive sensor provided by the utility model embodiment is shown in the figure.

[0030] Figure 4The utility model provides a kind of pressure control unit and circuit schematic diagram of solenoid for the utility model embodiment provides. DETAILED DESCRIPTION

[0031] In order to make the person in the technical field better understand the utility model scheme, the technical scheme in the embodiments of the utility model will be described clearly and completely below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only a part of the embodiments of the utility model, not all. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor should belong to the scope of protection of the utility model.

[0032] It should be noted that the terms "first", "second" and the like in the specification and claims of the utility model and the above drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the utility model described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0033] The utility model embodiment provides a kind of contact surface topography measuring device, its composition schematic diagram is as shown in Figure 1 The utility model embodiment provides a kind of contact surface topography measuring device, its composition schematic diagram is as shown in

[0034] Specifically, the test table 101 refers to a placement table for carrying the wafer to be measured, which can provide a placement plane for the wafer to be measured during the measurement process. In some embodiments, the movable assembly of the test table 101 can drive the placement plane and the wafer to be measured thereon to move relative to the probe 103. For example, the placement plane provided by the test table 101 can be parallel to the horizontal plane, and the movable assembly mechanically connected to the test table 101 can move horizontally relative to the probe 103 together with the wafer to be measured.

[0035] The probe 103 refers to a measurement needle in direct contact with the surface of the wafer to be measured. During the measurement process, the needle of the probe 103 is in contact with the surface of the wafer to be measured under the pressure provided by the pressure assembly 104, and slides on the surface of the wafer to be measured when the probe 103 moves relative to the wafer to be measured. The probe 103 will displace along the direction perpendicular to the placement plane according to the topography of the surface in contact, for example, during the test in which the probe 103 is above and the wafer to be measured is below, if the probe 103 slides to the recessed part of the surface of the wafer to be measured, the probe 103 will displace downward, and if the probe 103 slides to the protruding part of the surface of the wafer to be measured, the probe 103 will displace upward.

[0036] The pressure assembly 104 can provide pressure for the probe 103 and limit the activity direction and stroke of the probe 103. For example, the pressure assembly 104 can include an elastic force supply structure and / or an electromagnetic force supply structure. On the one hand, the elastic member in the elastic force supply structure can be mechanically connected to the root of the probe 103. During the test, the pressure control unit 106 can adjust the compression degree of the elastic member, so that the elastic force of the elastic member provides pressure for the probe 103 to press against the surface of the wafer to be measured. The elastic member can be a cross spring. On the other hand, the two ends of the electromagnetic coil in the electromagnetic force supply structure are connected to the pressure control unit 106, and the pressure-providing metal member in the electromagnetic force supply structure is arranged in the coil and is mechanically connected to the root of the probe 103. During the test, the pressure control unit 106 controls the power connected to the two ends of the electromagnetic coil, so as to provide an induced electromagnetic force for the pressure-providing metal member, so that the needle of the probe 103 connected thereto is pressed against the surface of the wafer to be measured and keeps in contact with the surface of the wafer to be measured.

[0037] The capacitive sensor 105 is a displacement sensor that detects displacement of the probe 103 by using a change in capacitance. The core principle of the capacitive sensor 105 is a capacitance formula C = εA / d, where C is capacitance, ε is dielectric constant, A is electrode area, and d is electrode spacing. Exemplarily, the capacitive sensor 105 can be a cylindrical capacitive sensor, a surface capacitive sensor, a single-capacitance sensor, a differential capacitive sensor, or the like. In the case where the capacitive sensor 105 is a single-capacitance sensor (not shown in the figure), the static electrode plate a is on the top and the dynamic electrode plate b is on the bottom. If the probe 103 needle slides to a protruding position on the surface of the wafer to be measured, the root of the probe 103 drives the dynamic electrode plate b of the capacitive sensor 105 to move close to the static electrode plate a, the electrode spacing becomes smaller, and the capacitance becomes larger. That is, the capacitance of the single-capacitance sensor can reflect the movement displacement of the probe 103 in the first direction. In the case where the capacitive sensor 105 is a differential capacitive sensor (shown in the figure), the dynamic electrode plate b is arranged between two static electrode plates a. If the probe 103 needle slides to a protruding position on the surface of the wafer to be measured, the root of the probe 103 drives the dynamic electrode plate b of the capacitive sensor 105 to move close to the static electrode plate a on the top, and the capacitance difference between the two capacitors formed by the dynamic electrode plate b and the two static electrode plates a changes. That is, the capacitance difference of the differential capacitive sensor can reflect the movement displacement of the probe 103 in the first direction, and the sampling accuracy is higher than that of the single-capacitance sensor.

[0038] The pressure control unit 106 refers to a circuit assembly for controlling the pressure provided by the pressure applying assembly 104. The pressure control unit 106 is electrically connected with the capacitive sensor 105, and can obtain the movement displacement sampling value of the probe 103 by the capacitive sensor 105. The pressure control unit 106 is also electrically connected with the pressure applying assembly 104, and can control the pressure provided by the pressure applying assembly 104 for the probe 103 according to the movement displacement sampling value of the probe 103, so that the pressure of the probe 103 needle on the surface of the wafer is reasonable. Exemplarily, taking the principle that the pressure applying assembly 104 adopts an electromagnetic coil to generate electromagnetic force to apply pressure to the probe 103 as an example, if the probe 103 scans to a protruding position of the wafer to be measured, it will be displaced upward relative to the initial position. The pressure control unit 106 detects the positive movement displacement, at this time, the pressure control unit 106 can reduce the current in the electromagnetic coil, thereby reducing the applied force of the pressure applying assembly 104 on the probe 103, to prevent the wafer surface from being damaged due to large frictional force when the probe 103 slides through the protrusion. Conversely, if the probe 103 scans to a recessed position of the wafer to be measured, it will be displaced downward relative to the initial position. The pressure control unit 106 detects the reverse movement displacement, at this time, the pressure control unit 106 can increase the current in the electromagnetic coil, thereby increasing the applied force of the pressure applying assembly 104 on the probe 103, to prevent the measurement stroke of the recessed position from being insufficient due to insufficient pressure when the probe 103 slides through the recess, resulting in low measurement accuracy.

[0039] With reference to the foregoing embodiments Figure 1 Another embodiment of the present application provides another possible structure of the pressure applying assembly 104, which includes an electromagnetic coil 201 and a metal pressure applying piece 202, the metal pressure applying piece 202 is sleeved in the electromagnetic coil 201 and mechanically connected with the probe 103. The two ends of the electromagnetic coil 201 are connected with the pressure control unit 106.

[0040] Specifically, the electromagnetic coil 201 is an electromagnetic device that generates a magnetic field by passing current through a wire, and the electromagnetic coil 201 is a spiral structure or a ring structure wound by a wire, which can include a multi-turn coil. The metal pressure applying piece 202 can be a ferromagnetic material, and the electromagnetic coil 201 will generate a magnetic field around it after being electrified. The metal pressure applying piece 202 will form a thrust force on the probe 103 under the action of the magnetic field, driving the needle of the probe 103 to press the surface of the wafer to be measured in the first direction. The pressure of the needle on the surface of the wafer to be measured is positively correlated with the size of the current in the coil, and the pressure control unit 106 can control the pressure of the probe 103 by adjusting the current passing through the electromagnetic coil 201. For example, the electromagnetic coil 201 can use a model XRR6H-6*10-3.0T electromagnetic coil.

[0041] The pressure applying assembly provided in the embodiment uses an electromagnetic coil to provide pressure for the probe. Compared with the scheme of using an elastic piece in the first embodiment, this scheme is more convenient and fast to adjust, and shortens the response time of pressure adjustment.

[0042] Optionally, Figure 2 Another composition schematic diagram of the contact type surface topography measurement device provided by the embodiment of the present application is provided, which is based on the foregoing embodiments, and refers to Figure 2 The pressure control unit 106 includes a controller 203, a voltage stabilizing chip 204, a digital-to-analog conversion chip 205, and an operational amplifier circuit 206. The controller 203 is electrically connected with the capacitive sensor 105, and the controller 203 is also in communication connection with the input end of the digital-to-analog conversion chip 205. The controller 203 generates a pressure control signal according to the sampling result of the motion displacement. The power supply end of the digital-to-analog conversion chip 205 is electrically connected with the output end of the voltage stabilizing chip 204, and the output end of the digital-to-analog conversion chip 205 is electrically connected with the electromagnetic coil 201. The digital-to-analog conversion chip 205 adjusts the current flowing through the electromagnetic coil 201 according to the pressure control signal.

[0043] Specifically, the controller 203 refers to a controller for controlling the output voltage of the digital-to-analog conversion chip 205 according to the sampling signal of the capacitance sensor 105. The controller 203 can generate a digital pressure control signal according to the sampling signal of the capacitance sensor 105 and transmit it to the digital-to-analog conversion chip 205, and the digital-to-analog conversion chip 205 and the subsequent circuit thereof adjust the current flowing through the electromagnetic coil 201 according to the pressure control signal. Exemplarily, the controller 203 can be a host computer or a micro control chip. In the case where the controller 203 is a host computer, the host computer can also restore the surface topography of the wafer under test according to the sampling signal of the capacitance sensor 105 and display the restored image.

[0044] The voltage stabilizing chip 204 is a reference voltage providing device of the digital-to-analog conversion chip 205. The input end of the voltage stabilizing chip 204 is connected to the main power supply of the circuit, and the output end of the voltage stabilizing chip 204 is electrically connected to the reference power supply end of the digital-to-analog conversion chip 205. The voltage stabilizing chip 204 can generate a stable preset voltage source according to the connected main power supply of the circuit and supply it to the digital-to-analog conversion chip 205. Exemplarily, the voltage stabilizing chip 204 can include a voltage stabilizer of model ADR4540BRZ, the input end of which can be connected to a +5V main power supply of the circuit, and the output end of which can output a +4.096V stable voltage source.

[0045] The digital-to-analog conversion chip 205 is an integrated circuit for converting a digital signal into a corresponding analog signal. The reference power supply end of the digital-to-analog conversion chip 205 is electrically connected to the output end of the voltage stabilizing chip 204, so as to determine the range and accuracy of the output analog signal according to the preset voltage source provided by the voltage stabilizing chip 204. The digital-to-analog conversion chip 205 can convert the digital pressure control signal provided by the controller 203 into an analog voltage signal and supply it to the electromagnetic coil 201 through the operational amplifier circuit 206. Exemplarily, the digital-to-analog conversion chip 205 can include a digital-to-analog converter of model LTC1650CS#PBF, which is electrically connected to the controller 203 through a serial peripheral interface (also referred to as SPI interface).

[0046] The operational amplifier circuit 206 can perform preset proportional operational amplification processing on the output voltage of the digital-to-analog conversion chip 205 and supply it to both ends of the series circuit of the electromagnetic coil 201 and the precision resistor. The current flowing through the electromagnetic coil 201 can be represented by I=t*VOUT / R, where I is the current flowing through the electromagnetic coil 201, VOUT is the output voltage of the digital-to-analog conversion chip 205, R is the resistance value of the precision resistor, and t is the operational amplification ratio of the operational amplifier circuit 206. The pressure provided by the pressure applying assembly 104 to the probe 103 can be represented by F=I*K, where K is a fixed coefficient related to the parameters of the electromagnetic coil 201 and the metal pressure applying piece 202, and I is the current flowing through the electromagnetic coil 201.

[0047] Exemplarily,Figure 3 The utility model provides a kind of structure schematic diagram of capacitive sensor for the embodiment of the utility model, combine Figure 2 And Figure 3 In the case where the capacitive sensor 105 is a differential capacitive sensor, the differential capacitive sensor connects two capacitors in parallel, forming an upper capacitor C m And a lower capacitor C n The common plate between the two capacitors is the moving plate b. When the moving plate b follows the probe 103 to displace up and down, the capacitance of the upper capacitor C m And the lower capacitor C n Will change according to the change of the corresponding electrode spacing d. At the same time, the charge carried by the upper and lower capacitors will also be transferred following the displacement of the moving plate b. The charges of the upper and lower capacitors are connected to the circuit by wires. After analysis and conversion by the circuit, the charge quantity is converted into a voltage signal that can be identified. After amplification and filtering by the subsequent circuit, the voltage signal is connected to the controller 203 for analysis and processing. According to the voltage value output by the differential capacitive sensor, the controller 203 can calculate the displacement of the moving plate b in the differential capacitive sensor. In order to maintain the pressure balance of the probe 103, the controller 203 controls the size of the magnetic attraction of the electromagnetic coil 201 according to the displacement of the moving plate b, that is, controls the increase and decrease of the current in the electromagnetic coil 201. According to the current formula I = t * VOUT / R of the electromagnetic coil 201, in order to control the increase and decrease of the current in the electromagnetic coil 201, the controller 203 can adjust the output voltage VOUT of the digital-analog conversion chip 205. According to the voltage value output by the differential capacitive sensor, the controller 203 adjusts the output voltage VOUT of the digital-analog conversion chip 205, which can complete the pressure balance and adaptation of the probe 103.

[0048] For example, after starting the measurement, the probe 103 first slides down to the measured surface of the wafer to be measured. The D / A conversion chip 205 outputs a preset voltage according to the initial pressure control signal output by the host computer, so that the pressure of the probe 103 on the measured surface is the initial pressure. Then the probe 103 starts to slide to measure the topography of the wafer to be measured. On the one hand, when encountering a protrusion on the measured surface, the probe 103 will displace upward along the first direction X, and the displacement amount is a positive displacement amount + AX. The capacitive sensor 105 can convert the positive displacement amount + AX into a corresponding positive voltage signal V+. The host computer can determine that the probe 103 detects the protrusion according to the positive voltage signal V+, and at this time, in order to keep the pressure of the probe 103 balanced, the host computer needs to reduce the magnetic attraction of the electromagnetic coil 201, that is, to reduce the current flowing through the electromagnetic coil 201. According to the formula I = t*VOUT / R, in order to reduce the current flowing through the electromagnetic coil 201, the host computer only needs to reduce the output voltage VOUT of the D / A conversion chip 205, and then the host computer can determine the reduction amount of the output voltage VOUT of the D / A conversion chip 205 according to the detected positive voltage signal V+, and generate a pressure control signal for reducing the magnetic attraction of the coil. The pressure control signal will control the output voltage of the D / A conversion chip 205 to decrease, so as to realize the current reduction of the electromagnetic coil 201, so that the probe 103 obtains an adaptive pressure.

[0049] On the other hand, it is also the same reason. When encountering a depression on the measured surface, the probe 103 will displace downward along the first direction X, and the displacement amount is a negative displacement amount - AX. The capacitive sensor 105 can convert the negative displacement amount - AX into a corresponding negative voltage signal V-. The host computer can determine that the probe 103 detects the depression according to the negative voltage signal V-, and at this time, in order to keep the pressure of the probe 103 balanced, the host computer needs to increase the magnetic attraction of the electromagnetic coil 201, that is, to increase the current flowing through the electromagnetic coil 201. According to the formula I = t*VOUT / R, in order to increase the current flowing through the electromagnetic coil 201, the host computer only needs to increase the output voltage VOUT of the D / A conversion chip 205, and then the host computer can determine the increase amount of the output voltage VOUT of the D / A conversion chip 205 according to the detected negative voltage signal V-, and generate a pressure control signal for increasing the magnetic attraction of the coil. The pressure control signal will control the output voltage of the D / A conversion chip 205 to increase, so as to realize the current reduction of the electromagnetic coil 201, so that the probe 103 obtains an adaptive pressure. Through the closed loop system formed between the probe 103, the capacitive sensor 105, the host computer, the D / A conversion chip 205 and the electromagnetic coil, continuous collection and feedback will be carried out during the test, and real-time dynamic control and adjustment of the electromagnetic coil will be carried out, so as to ensure that the pressure of the probe 103 on the measured surface is balanced during the whole test process.

[0050] The contact type surface topography measuring device provided by the embodiment comprises a pressure control unit, a probe, a capacitive sensor, an electromagnetic coil and a precision resistor.

[0051] Optionally, Figure 4 The circuit schematic diagram of the pressure control unit and the electromagnetic coil provided by the embodiment comprises the pressure control unit, the probe, the capacitive sensor, the electromagnetic coil and the precision resistor. Figure 2 and Figure 4 The operational amplification circuit 206 comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first capacitor C1, a first operational amplifier 301 and a second operational amplifier 302. The first input end of the first operational amplifier 301 is electrically connected with the output end of the digital-to-analog conversion chip 205 through the first resistor R1 and is grounded through the second resistor R2; the output end of the first operational amplifier 301 is electrically connected with the first input end of the second operational amplifier 302 through the third resistor R3 and is electrically connected with the second input end of the first operational amplifier 301. The first input end of the second operational amplifier 302 is grounded through the fourth resistor R4; the second input end of the second operational amplifier 302 is electrically connected with the output end of the first operational amplifier 301 through the fifth resistor R5 and the sixth resistor R6 in sequence; the output end of the second operational amplifier 302 is electrically connected with the second input end of the second operational amplifier 302 through the first capacitor C1; the connection point of the fifth resistor R5 and the sixth resistor R6 is taken as the first total output end c of the operational amplification circuit 206, the output end of the second operational amplifier 302 is taken as the second total output end d of the operational amplification circuit 206, and the first total output end c and the second total output end d are used for connecting the series circuit formed by the electromagnetic coil 201 and the precision resistor R0. In addition, the pressure control unit 106 can also optionally comprise a second capacitor C2 and a third capacitor C3. The input end of the voltage stabilizing chip 204 is grounded through the second capacitor C2; the output end of the voltage stabilizing chip 204 is grounded through the third capacitor C3.

[0052] Specifically, the first operational amplifier 301 and the second operational amplifier 302 and the peripheral circuit thereof can realize two-pole operational amplification of the output voltage VOUT of the digital-to-analog conversion chip 205, so as to be adapted to the electromagnetic coil 201 and the precision resistor R0 connected in series with the electromagnetic coil 201. For example, the first operational amplifier 301 and the second operational amplifier 302 can be selected as a dual-channel operational amplifier with a model number of TLC082AIDR.

[0053] The second capacitor C2 and the third capacitor C3 serve as decoupling capacitors, which can further improve the stability of the main power supply V1 and the reference voltage Vref and reduce noise, thereby improving the stability and anti-interference capability of the pressure control unit 106.

[0054] The above specific embodiments do not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A contact surface topography measuring device, characterized in that The utility model relates to a kind of wafer testing device, including: Test bench and measurement module; The test bench is used to place the wafer to be tested; The measurement module includes probe, pressure applying assembly, capacitive sensor and pressure control unit;The probe is mechanically connected with the pressure applying assembly, the needle of the probe is vertically arranged with the placement plane of the test bench, the pressure applying assembly provides pressure to the probe towards the placement plane, so that the needle of the probe keeps contact with the surface of the wafer to be tested;The capacitive sensor is mechanically connected with the probe, and the capacitive sensor can sample the movement displacement of the probe in the first direction, wherein the first direction is perpendicular to the placement plane;The pressure control unit is electrically connected with the capacitive sensor and the pressure applying assembly respectively, and the pressure control unit adjusts the pressure provided by the pressure applying assembly to the probe according to the sampling result of the movement displacement.

2. The apparatus of claim 1, wherein, The pressure applying assembly includes an electromagnetic coil and a metal pressure applying member, the metal pressure applying member is sleeved in the electromagnetic coil and mechanically connected with the probe;The two ends of the electromagnetic coil are connected with the pressure control unit.

3. The apparatus of claim 2, wherein, The pressure control unit includes a controller, a voltage stabilizing chip and a digital-to-analog conversion chip. The controller is electrically connected with the capacitive sensor, and the controller is also communicatively connected with the input end of the digital-to-analog conversion chip, and the controller generates a pressure control signal according to the sampling result of the movement displacement. The power supply end of the digital-to-analog conversion chip is electrically connected with the output end of the voltage stabilizing chip, and the output end of the digital-to-analog conversion chip is electrically connected with the electromagnetic coil, and the digital-to-analog conversion chip adjusts the current flowing through the electromagnetic coil according to the pressure control signal.

4. The apparatus of claim 3, wherein, The pressure control unit further includes an operational amplifier circuit. The operational amplifier circuit is arranged between the output end of the digital-to-analog conversion chip and the electromagnetic coil.

5. The apparatus of claim 4, wherein, The operational amplifier circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first capacitor, a first operational amplifier and a second operational amplifier. The first input end of the first operational amplifier is electrically connected with the output end of the digital-to-analog conversion chip through the first resistor and grounded through the second resistor, and the output end of the first operational amplifier is electrically connected with the first input end of the second operational amplifier through the third resistor and also electrically connected with the second input end of the first operational amplifier. The first input end of the second operational amplifier is grounded through the fourth resistor, the second input end of the second operational amplifier is electrically connected with the output end of the first operational amplifier in sequence through the fifth resistor and the sixth resistor, the output end of the second operational amplifier is electrically connected with the second input end of the second operational amplifier through the first capacitor, the connection point of the fifth resistor and the sixth resistor serves as the first total output end of the operational amplifier circuit, and the output end of the second operational amplifier serves as the second total output end of the operational amplifier circuit, and the first total output end and the second total output end are used to connect the electromagnetic coil.

6. The apparatus of claim 3, 4 or 5, wherein, The pressure control unit further includes a precision resistor, and the precision resistor is connected in series with the electromagnetic coil.

7. The apparatus of claim 3, wherein, The pressure control unit further comprises a second capacitor and a third capacitor. An input end of the voltage stabilizing chip is grounded through the second capacitor, and an output end of the voltage stabilizing chip is grounded through the third capacitor.

8. The apparatus of claim 3, wherein, The controller comprises an upper computer or a micro control chip.

9. The apparatus of any one of claims 1-5, 7, and 8, wherein, The capacitive sensor is a differential capacitive sensor.

10. The apparatus of any one of claims 1-5, 7, and 8, wherein, The capacitive sensor is a single capacitive sensor.

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