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CN114664685A - Thickness measurement system, method, electronic device and storage medium - Google Patents

Thickness measurement system, method, electronic device and storage medium Download PDF

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Publication number
CN114664685A
CN114664685A CN202210330645.6A CN202210330645A CN114664685A CN 114664685 A CN114664685 A CN 114664685A CN 202210330645 A CN202210330645 A CN 202210330645A CN 114664685 A CN114664685 A CN 114664685A
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China
Prior art keywords
thickness
feedback value
circuit
eddy current
current sensor
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CN202210330645.6A
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Chinese (zh)
Inventor
张康
李坤
李婷
张为强
尹影
崔云承
吴燕林
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Beijing Semicore Microelectronics Equipment Co Ltd
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Beijing Semicore Microelectronics Equipment Co Ltd
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Priority to CN202210330645.6A priority Critical patent/CN114664685A/en
Publication of CN114664685A publication Critical patent/CN114664685A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/10—Measuring as part of the manufacturing process
    • H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
    • G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
    • G01B7/10—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/02—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness
    • G01B7/06—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness
    • G01B7/10—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance
    • G01B7/105—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring length, width or thickness for measuring thickness using magnetic means, e.g. by measuring change of reluctance for measuring thickness of coating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
    • H01L22/26—Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

The invention discloses a thickness measuring system, a method, an electronic device and a storage medium, wherein the system comprises: the device comprises an eddy current sensor, a driving circuit, a sampling feedback circuit and a control unit, wherein the eddy current sensor comprises a first tap and a plurality of second taps; the driving circuit receives an externally input control instruction, generates oscillation current according to the control instruction, is connected with the eddy current sensor, generates an alternating magnetic field according to the oscillation current, and induces a sample to be detected according to the alternating magnetic field to generate a feedback value; the sampling feedback circuit collects a feedback value of the eddy current sensor and inputs the feedback value into the control unit, and the control unit controls the switching of the gears of the eddy current sensor according to the change of the feedback value. According to the system disclosed by the invention, the plurality of second taps are arranged in the eddy current sensor, so that the resonant frequency and the parallel capacitance with the best linearity and resolution can be matched when the sample is different in thickness, and the impedance matching and frequency selection within a wide thickness range are realized on hardware.

Description

Thickness measurement system, method, electronic device and storage medium
Technical Field
The invention relates to the technical field of integrated circuit manufacturing, in particular to a thickness measuring system, a thickness measuring device, electronic equipment and a storage medium.
Background
With the development of the integrated circuit manufacturing technology, the technical means of real-time feedback control of the surface topography of the wafer is gradually enhanced in different processes, so that the overall process capability and the product yield are improved. The measurement of the metal film on the surface of the integrated circuit wafer is generally realized by a contact type probe resistance measuring device or a non-contact type eddy current sensor, and the integrated on the process equipment is a non-contact type eddy current sensor module.
Generally, the technique for measuring the metal film thickness by using the probe resistance usually uses a measuring method for measuring the sheet resistance of the metal film by using the probe contact to calculate the metal film thickness, and is widely applied to an off-line metal film measuring process in the semiconductor manufacturing process. However, since the above measurement method is a contact type, the surface morphology and roughness of the wafer are affected, and contamination risk of the wafer is brought, which cannot be applied to the on-line measurement requirement of the process equipment. And the contact area of the probe limits the measurement range of the metal film at the edge of the wafer, so that a measurement blind area is caused, and complete measurement data cannot be obtained.
The eddy current technology for measuring the metal film thickness generally applies a certain frequency alternating voltage to a sensor coil, so that an LC circuit at the sensor end forms an oscillation circuit to generate an alternating magnetic field, the alternating magnetic field forms an eddy current effect on the surface of a metal film of a measured object to form a magnetic field opposite to the sensor coil, the apparent impedance of the sensor coil is changed, and the metal film thickness measurement is realized by associating the metal film thickness with related electrical parameters. The measurement mode has the advantages of non-contact, wide bandwidth, high environmental tolerance and the like, and is widely applied to an online measurement module of process equipment. However, the current mainstream eddy current online film thickness measurement system still has the problems of complex demodulation circuit, low stability, low linearity and resolution consistency of measurement of different thicknesses, and unreliable detection result caused by complex calibration process.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to overcome the defect of unreliable detection results for samples with different thicknesses in the prior art, so as to provide a thickness measuring system, a device, an electronic apparatus and a storage medium.
According to a first aspect, the invention discloses a thickness measurement system comprising: the eddy current sensor comprises a first tap and a plurality of second taps, and each second tap corresponds to a gear; the input end of the driving circuit receives an externally input control instruction, oscillation current is generated according to the control instruction, the output end of the driving circuit is connected with the eddy current sensor, the eddy current sensor generates an alternating magnetic field according to the oscillation current, and a sample to be detected is induced according to the alternating magnetic field to generate a feedback value; the sampling feedback circuit collects a feedback value of the eddy current sensor and inputs the feedback value to the control unit, and the control unit controls the switching of the gears of the eddy current sensor according to the change of the feedback value.
Optionally, the driving circuit comprises: the device comprises a clock circuit, a waveform generator, a power amplifier, an amplitude stabilizing circuit and a reference voltage circuit; the clock circuit inputs a clock signal to the waveform generator according to a control instruction of the control unit; the waveform generator generates a sine alternating-current waveform according to the clock signal; the reference voltage circuit is connected with the amplitude stabilizing circuit and inputs a reference voltage signal to the amplitude stabilizing circuit; the power amplifier receives the sine alternating current waveform, performs power amplification on the sine alternating current waveform, and then inputs the sine alternating current waveform to the amplitude stabilizing circuit, and the amplitude stabilizing circuit performs amplitude stabilization on the sine alternating current waveform after power amplification according to the reference voltage signal and then outputs oscillating current.
Optionally, the sampling feedback circuit includes: the device comprises a micro signal acquisition circuit, a micro signal amplification circuit, an alternating current-direct current conversion circuit and an analog-digital conversion circuit which are connected in sequence.
Optionally, the thickness measurement system further comprises: a data processing unit; and the data processing unit is connected with the control unit and is used for converting the feedback value into the thickness of the sample to be measured.
According to a second aspect, the present invention further discloses a thickness measurement method applied to the thickness measurement system according to any one of the optional embodiments of the first aspect and the first aspect, the thickness measurement method includes: acquiring a feedback value of a sample to be detected, which is sensed by an eddy current sensor; determining whether to switch the current gear of the eddy current sensor according to the feedback value and the change of the feedback value at the adjacent moment; and sensing the thickness of the sample to be measured at the next moment according to the switched gear.
Optionally, obtaining a feedback value of the sample to be measured sensed by the eddy current sensor includes: acquiring a theoretical feedback value-thickness curve of each gear and a thickness available interval corresponding to each gear; selecting a corresponding initial gear according to the initial thickness of the sample to be detected and the thickness available interval; and obtaining a feedback value of the sample to be detected according to the initial gear induction.
Optionally, determining whether to switch the current gear of the eddy current sensor according to the feedback value and the change of the feedback value at the adjacent time includes: determining the actual slope between two adjacent feedback values according to the feedback value; based on the currently selected gear, calculating a theoretical slope in a corresponding interval of the next gear according to a theoretical feedback value-thickness curve of the next gear; and when the difference between the actual slope and the theoretical slope is smaller than a preset slope difference threshold value, adjusting the eddy current sensor to the next gear.
Optionally, the obtaining a theoretical feedback value-thickness curve of each gear and a thickness available interval of each gear includes: respectively testing theoretical feedback values of the standard sample at different gears of the eddy current sensor; fitting and generating a theoretical feedback value-thickness curve of each gear according to the thickness of the standard sample and the theoretical feedback value; respectively calculating the theoretical interval slopes of the theoretical feedback value-thickness curve of each gear in different intervals; and when the slope of the theoretical interval is greater than a preset available slope threshold, taking the corresponding interval as the thickness available interval of the gear.
According to a third aspect, the invention also discloses an electronic device comprising: at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the steps of the thickness measurement method according to any one of the optional embodiments of the second aspect and the second aspect.
According to a fourth aspect, the present invention also discloses a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the thickness measurement method according to the second aspect and any one of the alternative embodiments of the second aspect.
The technical scheme of the invention has the following advantages:
1. according to the thickness measuring system disclosed by the invention, the plurality of second taps are arranged in the eddy current sensor, so that a plurality of gears can be provided for a single coil, and the gears of the eddy current sensor can be switched in real time according to the thickness of a sample when the thickness of the sample is different, so that the resonant frequency and the parallel capacitance with the best linearity and resolution are matched, and the impedance matching and frequency selection within a wide thickness range are realized on hardware. Through setting up drive circuit, can provide alternating current for eddy current sensor, make it can produce alternating magnetic field. Through setting up sampling feedback circuit, can gather the little change that takes place among the eddy current sensor to carry out the feedback through the signal of telecommunication.
2. According to the thickness measuring system disclosed by the invention, the clock circuit, the waveform generator, the power amplifier, the amplitude stabilizing circuit and the reference voltage circuit are respectively arranged, so that alternating current with proper amplitude can be provided for the eddy current sensor, and the eddy current sensor can generate a required alternating magnetic field. Through setting up small signal acquisition circuit, small signal amplifier circuit, alternating current-direct current converting circuit and analog-to-digital conversion circuit respectively, can gather and finally turn into digital signal the little change of eddy current sensor, realize that the accuracy of measurement is visual. Through setting up the data processing unit, can convert the signal of telecommunication into the sample thickness that awaits measuring and show to the user, realized thickness measurement system's human-computer interaction.
3. According to the thickness measuring method disclosed by the invention, the gears of the eddy current sensor are switched according to the feedback value and the change of the feedback value at the adjacent moment, the optimal matching relation of frequency and film thickness can be utilized to complete a large range of metal film thickness change, and the high-linearity high-resolution real-time thickness monitoring of the whole process of frequency conversion is realized.
4. According to the thickness measuring method disclosed by the invention, the feedback data and the metal film thickness are associated in a segmented manner through a theoretical feedback value-thickness curve, so that the thickness real-time monitoring with high linearity and high resolution in a wide range is realized, the repeatability and the consistency are high, and compared with the frequency conversion realized by complex circuit change, the method is simple and reliable. Through slope tracking comparison logic, frequency switching at proper time is realized, and a frequency conversion algorithm with reasonable consideration of linearity and resolution within a wide range is completed.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic block diagram of a specific example of a thickness measurement system in an embodiment of the invention;
FIG. 2 is a schematic block diagram of another specific example of a thickness measurement system in an embodiment of the invention;
FIG. 3 is a functional block diagram of another specific example of a thickness measurement system in an embodiment of the present invention;
FIG. 4 is a functional block diagram of another specific example of a thickness measurement system in an embodiment of the present invention;
FIG. 5 is a flow chart of a specific example of a thickness measurement method in an embodiment of the present invention;
FIG. 6 is a flowchart of another specific example of a thickness measurement method in an embodiment of the present invention;
FIG. 7 is a flowchart of another specific example of a thickness measurement method in an embodiment of the present invention;
fig. 8 is a diagram of a specific example of an electronic device in an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; the two elements may be directly connected or indirectly connected through an intermediate medium, or may be connected through the inside of the two elements, or may be connected wirelessly or through a wire. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The embodiment of the invention discloses a thickness measuring system, as shown in figure 1, comprising: the eddy current sensor comprises an eddy current sensor 1, a driving circuit 2, a sampling feedback circuit 3 and a control unit 4, wherein the eddy current sensor 1 comprises a first tap 11 and a plurality of second taps 12, and each second tap 12 corresponds to one gear; the input end of the driving circuit 2 receives an externally input control instruction, oscillation current is generated according to the control instruction, the output end of the driving circuit 2 is connected with the eddy current sensor 1, the eddy current sensor 1 generates an alternating magnetic field according to the oscillation current, and a feedback value is generated by inducing a sample to be detected according to the alternating magnetic field; the sampling feedback circuit 3 collects a feedback value of the eddy current sensor 1, the feedback value is input to the control unit 4, and the control unit 4 controls the switching of the gears of the eddy current sensor 1 according to the change of the feedback value.
Specifically, the drive circuit 2 is controlled by the control unit 4 to generate a sinusoidal alternating current waveform and output across the eddy current sensor 1. The eddy current sensor 1 generates an alternating magnetic field according to a sinusoidal alternating current waveform, and the magnetic field interacts with a sample to be measured, so that the apparent impedance of a coil in the eddy current sensor 1 changes. The change of the apparent impedance of a coil in the eddy current sensor 1 is measured through the sampling feedback circuit 3, the change of the feedback value is utilized to reflect the change of the metal film thickness of a wafer of a sample to be measured, when the wafer metal film interacts with the eddy current sensor 1 in the thinning process, the number of turns of the coil is switched by adjusting the gear corresponding to the second tap 12 in the eddy current sensor 1, the purpose of adjusting the inductance is achieved, the resonant frequency and the parallel capacitance with the best linearity and resolution are matched in different thickness ranges, and the impedance matching and frequency selection in a wide thickness range are realized on hardware.
According to the thickness measuring system disclosed by the invention, the plurality of second taps are arranged in the eddy current sensor, so that a plurality of gears can be provided for a single coil, and the gears of the eddy current sensor can be switched in real time according to the thickness of a sample when the thickness of the sample is different, so that the resonant frequency and the parallel capacitance with the best linearity and resolution are matched, and the impedance matching and frequency selection within a wide thickness range are realized on hardware. Through setting up drive circuit, can provide alternating current for eddy current sensor, make it can produce alternating magnetic field. Through setting up sampling feedback circuit, can gather the little change that takes place among the eddy current sensor to carry out the feedback through the signal of telecommunication.
As an alternative embodiment of the present invention, as shown in fig. 2, the driving circuit 2 includes: a clock circuit 21, a waveform generator 22, a power amplifier 23, an amplitude stabilizing circuit 24 and a reference voltage circuit 25; the clock circuit 21 inputs a clock signal to the waveform generator 22 according to a control instruction of the control unit 4; the waveform generator 22 generates a sinusoidal alternating current waveform according to the clock signal; the reference voltage circuit 25 is connected with the amplitude stabilizing circuit 24 and inputs a reference voltage signal to the amplitude stabilizing circuit 24; the power amplifier 23 receives the sinusoidal ac waveform, performs power amplification on the sinusoidal ac waveform, and inputs the sinusoidal ac waveform to the amplitude stabilizing circuit 24, and the amplitude stabilizing circuit 24 performs amplitude stabilization on the sinusoidal ac waveform after power amplification according to the reference voltage signal, and outputs an oscillating current.
The clock circuit 21 can generate an oscillation circuit that moves accurately like a clock, and can generate a pulse current at a standard frequency. The clock circuit is generally composed of a crystal oscillator, a crystal oscillator control chip and a capacitor. In particular, the clock circuit may be implemented by a crystal oscillator including a quartz crystal, and other clock circuit structures in the prior art may be selected, which is not limited by the present invention.
The waveform generator 22 is capable of generating a sinusoidal waveform signal of a periodic time function according to the pulse current frequency of the clock circuit, and providing alternating current for the eddy current sensor 1. In particular, the waveform generator 22 may first connect the hysteresis comparator and the integral comparator end to form a positive feedback closed-loop system, and then convert the triangular wave into a sine wave by low-pass filtering, or may adopt other waveform generator structures in the prior art, which is not limited in this disclosure.
Wherein, the power amplifier 23 can generate the maximum power output to drive the amplifier of the eddy current sensor 1 under the condition of a given distortion rate, and can amplify the alternating current generated by the waveform generator 22 so as to achieve the current amplitude required by driving the eddy current sensor 1. In particular, the power amplifier 23 may select to convert power by using the current control function of a triode or the voltage control function of a field effect transistor, or other power amplifier structures in the prior art, which is not limited by the invention.
The amplitude stabilizing circuit 24 can stabilize the amplitude of the alternating current signal amplified by the power amplifier by using the reference voltage provided by the reference circuit 25 as a threshold value, and prevent distortion generated in the amplification process. In particular, the amplitude stabilizing circuit 24 may employ a thermistor or other amplitude limiting circuit, which is not limited by the present invention.
The reference circuit 25 can provide a stable reference voltage for the amplitude stabilizing circuit 24 after the circuit is accessed, so that the amplitude stabilizing circuit can stabilize the amplitude by using the reference voltage as a reference voltage. In particular, the reference circuit 25 may be a voltage reference chip or other reference circuit in the prior art, which is not limited by the present invention.
As an alternative embodiment of the present invention, as shown in fig. 3, the sampling feedback circuit 3 includes: the micro signal acquisition circuit 31, the micro signal amplification circuit 32, the alternating current-direct current conversion circuit 33 and the analog-digital conversion circuit 34 are connected in sequence.
Wherein the minute signal collecting circuit 31 can collect minute voltage and current variations. After the coil of the eddy current sensor 1 is affected by the thickness change of the metal film of the wafer, the apparent impedance changes, and the change of the apparent impedance can be reflected by the tiny voltage and current changes, and the tiny voltage and current changes are acquired by the tiny signal acquisition circuit 31, so that the change of the coil apparent impedance in the eddy current sensor 1 can be obtained. In particular, the minute signal collecting circuit 31 may be composed of a minute current signal collecting circuit and a minute voltage signal collecting circuit, and other signal collecting circuits in the prior art may also be adopted, which is not limited in the present invention.
The minute signal amplifying circuit 32 can amplify the minute signal acquired by the minute signal acquiring circuit 31, so as to facilitate the subsequent signal processing step. In particular, the small signal amplifying circuit 32 may be implemented by using components such as an operational amplifier or an integrated amplifier in the prior art, which is not limited by the present invention.
The ac/dc conversion circuit 33 can accurately convert the effective value of the amplified ac signal into a dc signal for output, so as to perform an analog-to-digital conversion operation. In particular, the ac/dc conversion circuit 33 may be implemented by a rectifier circuit composed of a plurality of rectifier diodes, or may be implemented by other components such as an ac/dc converter in the prior art, which is not limited in the present invention.
The analog-to-digital conversion circuit 34 can sample the dc signal converted by the ac-to-dc conversion circuit 33, and then quantizes and encodes the dc signal into a binary digital signal, which is convenient for the control unit to process. In particular, the analog-to-Digital Conversion circuit 34 may be implemented by an analog-to-Digital converter (ADC) in the prior art, and may also be implemented by other analog-to-Digital Conversion components, which is not limited in the present invention.
As an alternative embodiment of the present invention, as shown in fig. 4, the thickness measuring system further includes: a data processing unit 5; and the data processing unit 5 is connected with the control unit 4 and is used for converting the feedback value into the thickness of the sample to be measured.
Specifically, the data processing unit 5 may be a computer or a single chip microcomputer capable of directly sending an operation instruction, and may provide a user operation interaction interface and present feedback data to the user. Through an upper computer algorithm, the function of converting the feedback value into the thickness of the sample to be measured can be realized.
According to the thickness measuring system disclosed by the invention, the clock circuit, the waveform generator, the power amplifier, the amplitude stabilizing circuit and the reference voltage circuit are respectively arranged, so that alternating current with proper amplitude can be provided for the eddy current sensor, and the eddy current sensor can generate a required alternating magnetic field. Through setting up small signal acquisition circuit, small signal amplifier circuit, alternating current-direct current conversion circuit and analog-to-digital conversion circuit respectively, can gather and finally turn into digital signal the little change of eddy current sensor, realize that the measuring is accurate visual. Through setting up the data processing unit, can convert the signal of telecommunication into the sample thickness that awaits measuring and show to the user, realized thickness measurement system's human-computer interaction.
The embodiment of the invention also discloses a thickness measuring method, which is applied to the thickness measuring system according to the system embodiment of the invention and any optional implementation mode in the system embodiment of the invention, and as shown in fig. 5, the thickness measuring method comprises the following steps:
and step S1, obtaining the feedback value of the sample to be measured induced by the eddy current sensor.
Specifically, the eddy current sensor in the thickness measuring system generates an alternating magnetic field according to the sinusoidal alternating current waveform generated by the driving circuit 2, and the alternating magnetic field interacts with the sample to be measured, so that the apparent impedance of the coil in the eddy current sensor 1 changes. The feedback value can be obtained by measuring the change of the apparent impedance of the coil in the eddy current sensor 1 through the sampling feedback circuit 3.
And step S2, determining whether to switch the current gear of the eddy current sensor according to the feedback value and the change of the feedback value at the adjacent moment.
Specifically, the thickness of the sample at the current moment can be determined according to the feedback value, and the resolution of the current gear can be judged according to the change of the feedback values at the adjacent moments. According to the thickness and the resolution ratio, a proper gear is selected for switching, so that the proper resonant frequency and impedance matching can be achieved under the current thickness value, and the linearity and the resolution ratio in the measuring process are ensured.
And step S3, sensing the thickness of the sample to be measured at the next moment according to the switched gear.
Further, the steps of steps S1-S3 are repeated until a preset final thickness is reached, and the thickness measurement process is completed.
According to the thickness measuring method disclosed by the invention, the gears of the eddy current sensor are switched according to the feedback value and the change of the feedback value at the adjacent moment, the optimal matching relation of frequency and film thickness can be utilized to complete a large range of metal film thickness change, and the high-linearity high-resolution real-time thickness monitoring of the whole process of frequency conversion is realized.
As an alternative embodiment of the present invention, as shown in fig. 6, the obtaining of the feedback value of the sample to be measured sensed by the eddy current sensor includes the following steps:
and step S11, obtaining the theoretical feedback value-thickness curve of each gear and the thickness available interval corresponding to each gear.
Specifically, in the process of obtaining the theoretical feedback value-thickness curve of each gear and the thickness available interval corresponding to each gear, the theoretical feedback values of the standard sample can be respectively tested at different gears of the eddy current sensor; then, according to the thickness of the standard sample and the theoretical feedback value, fitting to generate a theoretical feedback value-thickness curve of each gear; then respectively calculating the theoretical interval slope of the theoretical feedback value-thickness curve of each gear in different intervals; and finally, when the slope of the theoretical interval is greater than a preset available slope threshold value, taking the corresponding interval as the thickness available interval of the gear. In particular, the standard sample refers to a sample having a known thickness and a uniform thickness.
The process of obtaining the theoretical feedback value-thickness curve of each gear can be realized by selecting a corresponding number of standard samples according to the thickness range required by measurement; then, respectively testing theoretical feedback values at different vortex sensor gears by using the standard sample; and finally, fitting and generating a theoretical feedback value-thickness curve of each gear according to the thickness of the standard sample and the corresponding theoretical feedback value.
Illustratively, taking the measurement range of 0-10000nm as an example, according to the interval of 2000nm, standard samples with the thicknesses of 2000nm, 4000nm, 6000nm, 8000nm and 10000nm are selected, the eddy current sensor is placed in the first grade, the 5 samples are sequentially measured to obtain corresponding 5 theoretical feedback values sensed by the eddy current sensor, and fitting is performed according to the 5 theoretical feedback values to generate a feedback value-thickness curve of the first grade. Similarly, the eddy current sensor is placed in each gear, and the process is repeated to generate a feedback value-thickness curve of each gear. In particular, the greater the accuracy required for thickness measurement, the smaller the thickness interval of the standard samples, the greater the number of standard samples that need to be selected, whereas the smaller the accuracy required for thickness measurement, the greater the thickness interval of the standard samples, the fewer the number of standard samples that need to be selected. The selection interval and the selection number of the standard samples can be selected according to the actual required precision, and the invention is not limited to this.
In the process of obtaining the thickness available interval corresponding to each gear, a theoretical interval slope between any two points can be calculated according to the feedback value-thickness curve of each gear, and then when the theoretical interval slope is greater than a preset available slope threshold, the corresponding interval is used as the thickness available interval of the gear; or traversing the connecting line of any two points in the feedback value-thickness curve according to a preset available slope threshold value, so as to find a corresponding interval when the slope of the theoretical interval is greater than the preset available slope threshold value, and taking the corresponding interval as the thickness available interval of the gear.
And step S12, selecting a corresponding initial gear according to the initial thickness of the sample to be detected and the thickness available interval.
Specifically, according to the initial thickness of the sample to be measured, the thickness available interval of each gear is traversed, and the gear which contains the initial thickness and has the highest frequency in the thickness available interval is selected as the initial gear. In particular, the initial thickness of the sample to be measured may be obtained by rough measurement by selecting a gear with the highest frequency of the eddy current sensor, and may also be obtained by other detection methods, which is not limited in the present invention.
And step S13, obtaining a feedback value of the sample to be detected according to the initial gear induction.
As an alternative embodiment of the present invention, as shown in fig. 7, determining whether to switch the current gear of the eddy current sensor according to the feedback value and the change of the feedback value at the adjacent time includes the following steps:
and step S21, determining the actual slope between two adjacent feedback values according to the feedback values.
Specifically, the actual slope of the current measurement curve is calculated according to the current feedback value and the feedback value at the last moment.
And step S22, based on the currently selected gear, calculating the theoretical slope in the corresponding interval of the next gear according to the theoretical feedback value-thickness curve of the next gear.
Specifically, the current thickness value and the last thickness value are obtained according to the current feedback value and the last feedback value. And then, calculating the theoretical slope between the current thickness value and the last-time thickness value according to the theoretical feedback value-thickness curve of the next gear.
And step S23, when the difference between the actual slope and the theoretical slope is smaller than a preset slope difference threshold value, adjusting the eddy current sensor to the next gear.
Specifically, when the difference between the actual slope and the theoretical slope is smaller than a preset slope difference threshold, it may be considered that the current actual slope matches the theoretical slope of the next gear, and the influence caused by the gear shift may be minimized by performing the shift.
According to the thickness measuring method disclosed by the invention, the feedback data and the thickness of the metal film are associated in a segmented manner through a theoretical feedback value-thickness curve, so that the thickness real-time monitoring with high linearity and high resolution in a wide range is realized, the repeatability and the consistency are high, and the method is simple and reliable compared with the method for realizing frequency conversion by complicated circuit change. Through slope tracking comparison logic, frequency switching at proper time is realized, and a frequency conversion algorithm with reasonable consideration of linearity and resolution within a wide range is completed.
An embodiment of the present invention further provides an electronic device, as shown in fig. 8, the electronic device may include a processor 101 and a memory 102, where the processor 101 and the memory 102 may be connected by a bus or in another manner, and fig. 8 takes the connection by the bus as an example.
The processor 101 may be a Central Processing Unit (CPU). The Processor 101 may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or combinations thereof.
The memory 102, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the thickness measurement system in embodiments of the present invention. The processor 101 executes various functional applications and data processing of the processor by executing non-transitory software programs, instructions and modules stored in the memory 102, that is, implements the thickness measurement system in the above-described method embodiments.
The memory 102 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor 101, and the like. Further, the memory 102 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 102 may optionally include memory located remotely from processor 101, which may be connected to processor 101 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
One or more modules are stored in memory 102 and, when executed by processor 101, perform a thickness measurement system as in the embodiment shown in FIG. 5.
Although the present invention has been described in detail with respect to the exemplary embodiments and the advantages thereof, those skilled in the art will appreciate that various changes, substitutions and alterations can be made to the embodiments without departing from the spirit and scope of the invention as defined by the appended claims. For other examples, one of ordinary skill in the art will readily appreciate that the order of the process steps may be varied while maintaining the scope of the present invention.
Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (10)

1. A thickness measurement system, comprising: the eddy current sensor comprises a first tap and a plurality of second taps, and each second tap corresponds to one gear;
the input end of the driving circuit receives an externally input control instruction, oscillation current is generated according to the control instruction, the output end of the driving circuit is connected with the eddy current sensor, the eddy current sensor generates an alternating magnetic field according to the oscillation current, and a sample to be detected is induced according to the alternating magnetic field to generate a feedback value;
the sampling feedback circuit collects a feedback value of the eddy current sensor and inputs the feedback value to the control unit, and the control unit controls the switching of the gears of the eddy current sensor according to the change of the feedback value.
2. The thickness measurement system of claim 1, wherein the drive circuit comprises: the device comprises a clock circuit, a waveform generator, a power amplifier, an amplitude stabilizing circuit and a reference voltage circuit;
the clock circuit inputs a clock signal to the waveform generator according to a control instruction of the control unit; the waveform generator generates a sine alternating-current waveform according to the clock signal;
the reference voltage circuit is connected with the amplitude stabilizing circuit and inputs a reference voltage signal to the amplitude stabilizing circuit; the power amplifier receives the sine alternating current waveform, performs power amplification on the sine alternating current waveform, and then inputs the sine alternating current waveform to the amplitude stabilizing circuit, and the amplitude stabilizing circuit performs amplitude stabilization on the sine alternating current waveform after power amplification according to the reference voltage signal and then outputs oscillating current.
3. The thickness measurement system of claim 1, wherein the sampling feedback circuit comprises: the device comprises a micro signal acquisition circuit, a micro signal amplification circuit, an alternating current-direct current conversion circuit and an analog-digital conversion circuit which are connected in sequence.
4. The thickness measurement system of claim 1, further comprising: a data processing unit;
and the data processing unit is connected with the control unit and is used for converting the feedback value into the thickness of the sample to be measured.
5. A thickness measuring method applied to the thickness measuring system according to any one of claims 1 to 4, the thickness measuring method comprising:
acquiring a feedback value of a sample to be detected, which is sensed by an eddy current sensor;
determining whether to switch the current gear of the eddy current sensor according to the feedback value and the change of the feedback value at the adjacent moment;
and sensing the thickness of the sample to be measured at the next moment according to the switched gear.
6. The method of claim 5, wherein obtaining feedback values of the sample to be measured sensed by the eddy current sensor comprises:
acquiring a theoretical feedback value-thickness curve of each gear and a thickness available interval corresponding to each gear;
selecting a corresponding initial gear according to the initial thickness of the sample to be detected and the thickness available interval;
and obtaining a feedback value of the sample to be detected according to the initial gear induction.
7. The thickness measuring method according to claim 5, wherein determining whether to switch a current shift position of the eddy current sensor based on the feedback value and a change in the feedback value at an adjacent time comprises:
determining an actual slope between two adjacent feedback values according to the feedback value;
based on the currently selected gear, calculating a theoretical slope in a corresponding interval of the next gear according to a theoretical feedback value-thickness curve of the next gear;
and when the difference between the actual slope and the theoretical slope is smaller than a preset slope difference threshold value, adjusting the eddy current sensor to the next gear.
8. The method for measuring the thickness according to claim 6, wherein the obtaining of the theoretical feedback value-thickness curve for each step and the thickness available interval for each step comprises:
respectively testing theoretical feedback values of the standard sample at different gears of the eddy current sensor;
fitting and generating a theoretical feedback value-thickness curve of each gear according to the thickness of the standard sample and the theoretical feedback value;
respectively calculating the theoretical interval slopes of the theoretical feedback value-thickness curve of each gear in different intervals;
and when the slope of the theoretical interval is greater than a preset available slope threshold, taking the corresponding interval as the thickness available interval of the gear.
9. An electronic device, comprising: at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to cause the at least one processor to perform the steps of the thickness measurement method of any one of claims 5-8.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the thickness measurement method according to any one of claims 5 to 8.
CN202210330645.6A 2022-03-30 2022-03-30 Thickness measurement system, method, electronic device and storage medium Pending CN114664685A (en)

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