CN113959326A - Metal film thickness measuring device capable of preventing metal pollution - Google Patents
Metal film thickness measuring device capable of preventing metal pollution Download PDFInfo
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- CN113959326A CN113959326A CN202111506801.1A CN202111506801A CN113959326A CN 113959326 A CN113959326 A CN 113959326A CN 202111506801 A CN202111506801 A CN 202111506801A CN 113959326 A CN113959326 A CN 113959326A
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Classifications
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- G—PHYSICS
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- 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
Abstract
The invention discloses a metal film thickness measuring device capable of preventing metal pollution, which comprises: the eddy current sensor comprises a magnetic core and a coil, wherein the coil is wound on the outer peripheral wall of the magnetic core along the circumferential direction of the magnetic core; the preposed signal processing module is connected with the eddy current sensor and used for inputting a sinusoidal excitation signal to the eddy current sensor and acquiring a voltage signal related to the thickness of the metal film through the eddy current sensor; the data acquisition processing module is connected with the preposed signal processing module and used for receiving the voltage signal output by the preposed signal processing module, converting the voltage signal into a digital signal and converting the digital signal into a corresponding film thickness value according to a prestored thickness calibration table; and the communication module is used for realizing communication between the data acquisition processing module and the upper computer.
Description
Technical Field
The invention relates to the technical field of chemical mechanical polishing, in particular to a metal film thickness measuring device capable of preventing metal pollution.
Background
Chemical Mechanical Polishing (CMP) is one means of achieving global planarization in integrated circuit fabrication. With the rapid development of integrated circuit manufacturing technology, the growth, characterization and non-contact precise measurement of the thickness of nanometer metal films are very important. Specifically, in the chemical mechanical polishing process, an eddy current sensor is usually used to perform online measurement on the thickness of the film, so as to control the process parameters of the polishing process, realize accurate removal of the metal film on the surface of the wafer, and stop polishing when the specified thickness value is removed.
However, the sensors based on the eddy current effect all need to use metal materials, metal ions can be generated to diffuse into the production environment to cause metal pollution, and the metal pollution can cause inaccurate measurement of the metal film thickness on one hand, and on the other hand, the problems that the wafer surface is scratched by the metal pollutants and/or the metal pollutants exceed the standard easily occur in the chemical mechanical polishing process.
Disclosure of Invention
The embodiment of the invention provides a metal film thickness measuring device capable of preventing metal pollution, and aims to at least solve one of the technical problems in the prior art.
The embodiment of the invention provides a metal film thickness measuring device capable of preventing metal pollution, which comprises:
an eddy current sensor including a magnetic core and a coil wound around an outer peripheral wall of the magnetic core in a circumferential direction of the magnetic core; the eddy current sensor further comprises an electromagnetic shielding shell, wherein a containing cavity for containing the magnetic core and the coil is defined in the electromagnetic shielding shell, a core layer of the electromagnetic shielding shell is made of a metal material, and the surface of the electromagnetic shielding shell is coated with a non-metal material layer so as to prevent metal ion pollution;
the preposed signal processing module is connected with the eddy current sensor and is used for inputting a sinusoidal excitation signal to the eddy current sensor and acquiring a voltage signal related to the thickness of the metal film through the eddy current sensor, wherein the frequency of the sinusoidal excitation signal is determined by the thickness range of the metal film to be measured and the type of the metal; the preposed signal processing module comprises a constant voltage source, a resonant capacitor and a divider resistor, wherein the divider resistor is connected with the eddy current sensor in parallel and then connected with the resonant capacitor and the constant voltage source in series;
the data acquisition processing module is connected with the preposed signal processing module and used for receiving the voltage signal output by the preposed signal processing module, converting the voltage signal into a digital signal and converting the digital signal into a corresponding film thickness value according to a prestored thickness calibration table;
and the communication module is used for realizing the communication between the data acquisition and processing module and the upper computer.
In one embodiment, the resonance capacitance may be calculated according to the following equation:
wherein f is0For a selected target excitation frequency, L is the inductance of the eddy current sensor, C is the capacitance of the resonant capacitor, and r is the internal resistance of the eddy current sensor.
In one embodiment, the divider resistance takes the real part of the impedance across the eddy current sensor at resonance.
In one embodiment, the eddy current sensor further comprises an encapsulation housing, and the encapsulation housing is provided with a groove for accommodating the electromagnetic shielding shell provided with the magnetic core and the coil.
In one embodiment, the magnetic core is a cuboid, the length of the magnetic core is 2-10 times of the width of the magnetic core, the width of the magnetic core is 2-4mm, and the height of the magnetic core is 1-3 mm; the coil is wound on the outer peripheral wall of the magnetic core along the circumferential direction of the cross section of the magnetic core, wherein the cross section is perpendicular to the height direction of the magnetic core.
In one embodiment, the magnetic core material is a nickel zinc ferrite or a manganese zinc ferrite.
In one embodiment, the coil is wound from enameled copper wire having a diameter of 0.05mm to 0.2 mm.
The embodiment of the invention has the beneficial effects that: the eddy current sensor is provided with an electromagnetic shielding shell, and the surface of the electromagnetic shielding shell is coated with a non-metallic material layer so as to prevent metal ion pollution and improve the accuracy of metal film thickness measurement and the accuracy of chemical mechanical polishing process control.
Drawings
The advantages of the invention will become clearer and more readily appreciated from the detailed description given with reference to the following drawings, which are given by way of illustration only and do not limit the scope of protection of the invention, wherein:
FIG. 1 is a schematic diagram illustrating a metal film thickness measuring apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an eddy current sensor according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a magnetic core according to an embodiment of the present invention;
FIG. 4 is a line graph of the composition of the metal film thickness measurement data;
FIG. 5 is a circuit diagram of a preamble signal processing module according to an embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating a parameter setting process of a metal film thickness measuring apparatus according to an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a chemical mechanical polishing apparatus according to an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of an eddy current sensor according to an embodiment of the present invention;
fig. 9 is a schematic view illustrating a measurement principle of an eddy current sensor according to an embodiment of the present invention.
Detailed Description
The technical solution of the present invention will be described in detail with reference to the following embodiments and accompanying drawings. The embodiments described herein are specific embodiments of the present invention for the purpose of illustrating the concepts of the invention; the description is intended to be illustrative and exemplary and should not be taken to limit the scope of the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification thereof, and these technical solutions include technical solutions which make any obvious replacement or modification of the embodiments described herein. It should be understood that, unless otherwise specified, the following description of the embodiments of the present invention is made for the convenience of understanding, and the description is made in a natural state where relevant devices, apparatuses, components, etc. are originally at rest and no external control signals and driving forces are given.
Further, it is also noted that terms used herein such as front, back, up, down, left, right, top, bottom, front, back, horizontal, vertical, and the like, to denote orientation, are used merely for convenience of description to facilitate understanding of relative positions or orientations, and are not intended to limit the orientation of any device or structure.
In order to explain the technical means of the present invention, the following description will be given by way of specific examples.
In the present application, Chemical Mechanical Polishing (Chemical Mechanical Planarization) is also called Chemical Mechanical Planarization (Chemical Mechanical Planarization), and wafer (wafer) is also called substrate (substrate), which means and actually functions equally.
As shown in fig. 1, an embodiment of the present invention provides a metal film thickness measuring apparatus 100, including:
an eddy current sensor 10 including a core 11 and a coil 12, the coil 12 being wound around an outer peripheral wall of the core 11 in a circumferential direction of the core 11; the eddy current sensor 10 further includes an electromagnetic shielding case 13, the electromagnetic shielding case 13 defining therein a receiving cavity for receiving the magnetic core 11 and the coil 12, a core layer of the electromagnetic shielding case 13 being made of a metal material and having a surface coated with a non-metal material layer to prevent metal ion contamination;
the preposed signal processing module 20 is connected with the eddy current sensor 10 and is used for inputting a sinusoidal excitation signal to the eddy current sensor 10 and acquiring a voltage signal related to the thickness of the metal film through the eddy current sensor 10, wherein the frequency of the sinusoidal excitation signal is determined by the thickness range of the metal film to be measured and the type of the metal;
the data acquisition processing module 30 is connected with the preposed signal processing module 20 and used for receiving the voltage signal output by the preposed signal processing module 20, converting the voltage signal into a digital signal and converting the digital signal into a corresponding film thickness value according to a prestored thickness calibration table;
and the communication module 40 is used for realizing communication between the data acquisition processing module 30 and an upper computer.
In the embodiment of the present invention, the electromagnetic shielding shell 13 is a multilayer structure, and the core layer thereof is made of a metal material, so that electromagnetic interference in the environment can be shielded, and a magnetic field generated by the eddy current sensor 10 can penetrate through the upper region thereof as much as possible; the surface of the electromagnetic shielding shell 13 is coated with a non-metallic material layer, which can prevent metal ions generated by the magnetic core 11, the coil 12 and the metal material in the core layer from diffusing to the production environment to cause metal pollution, thereby ensuring the accuracy of metal film thickness measurement and preventing the wafer surface from being scratched by metal pollutants and/or the metal pollutants from exceeding the standard in the chemical mechanical polishing process.
In one embodiment, the core layer of the electromagnetic shielding shell 13 is made of aluminum.
The non-metallic material layer of the electromagnetic shielding shell 13 is made of at least one material selected from plastic, ceramic and glass, and preferably, hard engineering plastic can be used. The hard engineering plastic can be hard polyvinyl chloride, polyethylene, organic glass, polypropylene, polystyrene, polytetrafluoroethylene, nylon, PET, ABS, PEEK and/or PPS. The thickness of the non-metallic material layer is 0.5mm-5 mm.
The eddy current sensor 10 is used for generating an alternating detection magnetic field, and converting the detected metal film thickness into an impedance signal of the coil 12 through magnetic field energy coupling of mutual inductance effect. The preposed signal processing module 20 inputs a sinusoidal excitation signal to the eddy current sensor 10 to convert the impedance signal into a voltage signal and performs detection rectification, filtering and amplification on the voltage signal, wherein the frequency of the sinusoidal excitation signal is determined by the metal film thickness range and the metal type to be measured. The data acquisition processing module 30 comprises a single chip microcomputer, and the single chip microcomputer converts the digital signals into corresponding film thickness values according to a prestored thickness calibration table.
As shown in fig. 2, in one embodiment of the present invention, the eddy current sensor 10 includes a magnetic core 11 having a rectangular parallelepiped shape and a coil 12 wound around the magnetic core 11 in a circumferential direction. The magnetic core 11 is made of nickel-zinc ferrite or manganese-zinc ferrite, preferably nickel-zinc ferrite with 1000 permeability or manganese-zinc ferrite with 2000 permeability. The coil 12 is wound on the outer peripheral wall of the core 11 circumferentially along a cross section of the core 11, wherein the cross section is perpendicular to the height direction of the core 11. The coil 12 is wound from an enameled copper wire having a diameter of 0.05mm to 0.2mm, preferably 0.1 mm.
As shown in FIG. 3, the length L of the rectangular parallelepiped core 11 is 2 to 10 times the width W, the width W of the core 11 may be 2 to 4mm, and the height H of the core 11 may be 1 to 3 mm.
The number of turns of the wound coil 12 can be 40-160 turns, and multilayer multi-turn winding can be carried out. For a metal film with low conductivity, such as a tungsten film, a larger number of turns of the coil 12, such as 120 turns, should be selected; for a metal film with higher conductivity, such as a copper film, a smaller number of turns of the coil 12, such as 60 turns, may be selected.
In this embodiment, the eddy current sensor 10 is used as a core part of the metal film thickness measuring apparatus 100, and is mainly used for generating an eddy current for exciting the metal film to be measured, converting the metal film thickness to be measured into an impedance signal of the coil 12 through magnetic field energy coupling of a mutual inductance effect, collecting a voltage signal converted from the impedance signal through the preposed signal processing module 20, and detecting the film thickness by using a linear mapping relationship between the voltage signal and the film thickness. In addition, the coil 12 with the magnetic core 11 can enable the magnetic field intensity excited by the coil 12 to be larger, and thickness measurement can be realized under a larger lift-off height, namely within a lift-off height range of 1mm-4 mm; the magnetic field spatial distribution is more concentrated above the magnetic core 11, and the distribution range along the width direction of the magnetic core 11 is generally less than twice the width of the magnetic core 11. Meanwhile, a larger area range can be measured along the length direction of the magnetic core 11, so that more metal film thickness information on the surface of the wafer w can be obtained.
As shown in fig. 4, taking the measurement of metal tungsten as an example, the eddy current sensor 10 provided by the present application can be implemented
Sub-nanometer thickness resolution. In the figure, R2Is the correlation coefficient of the curve and the straight line, the closer to 1, the better the fitting effect.
As shown in fig. 5, in one embodiment, the preposition signal processing module 20 may include a constant voltage source AC providing a sinusoidal excitation signal whose frequency is determined by the metal film thickness range and the metal type to be measured, and a voltage division amplitude modulation circuit for collecting the voltage signal across the eddy current sensor 10. As shown in fig. 5, the voltage-dividing amplitude modulation circuit includes a resonant capacitor C1 and a voltage-dividing resistor R1, and the voltage-dividing resistor R1 is connected in parallel with the eddy current sensor 10 and then connected in series with the resonant capacitor C1 and the constant voltage source AC.
In order to allow the magnetic field generated by the eddy current sensor 10 to completely penetrate the target metal thin film, the skin depth at the excitation frequency is larger than the target metal film thickness. The skin depth calculation formula is as follows:
wherein, delta is the skin depth, and the unit is millimeter mm; f is the excitation frequency in Hz; mu is magnetic conductivity, and the unit is Henry per meter H/m; sigma is the conductivity, with the unit of Siemens per meter S/m.
The excitation frequency range selected by the embodiment of the invention is 400KHz-4MHz, and the required target excitation frequency f is determined according to the metal film thickness range and the metal type to be measured0The smaller the range of the thickness of the metal film to be measured and the smaller the electrical conductivity of the metal to be measured, the selected target excitation frequency f0The larger the need.
In order to obtain as high a thickness resolution as possible, the resonant capacitance C1 matched in the voltage-dividing amplitude modulation circuit shown in FIG. 5 can be used according to the following formula with the selected target excitation frequency f0And calculating to obtain:
where L is the inductance of the eddy current sensor 10, C is the capacitance of the resonant capacitor C1, and r is the internal resistance of the eddy current sensor 10.
The impedance Z at both ends of the eddy current sensor 10 when the voltage dividing resistor R1 of the voltage dividing amplitude modulation circuit shown in FIG. 5 is in resonanceLCCan make the voltage across the eddy current sensor 10 follow the impedance Z across the eddy current sensorLCThe variation value of (2) is the largest, thereby achieving the effect of improving the thickness measurement sensitivity.
As shown in fig. 6, the parameter setting process of the metal film thickness measuring apparatus includes:
1) determining the required target excitation frequency f according to the metal film thickness range and the metal type to be measured0；
2) According to target excitation frequency f0A resonant capacitor C1 and a voltage dividing resistor R1 of the voltage dividing type amplitude modulation circuit are reversely deduced;
3) the matching circuit board system adjusts parameters of a rectifying circuit, a filtering circuit and an amplifying circuit;
4) calibrating the metal film thickness measuring device through a group of standard sample wafers with known thicknesses;
5) measuring another group of sample wafers with known thickness by using a metal film thickness measuring device to obtain a measured value;
6) judging whether the (measured value-real value)/real value is smaller than a given error value, wherein the real value is the known thickness of the sample wafer;
7) if not, returning to the step 3); if yes, the parameter setting is successful.
As shown in fig. 7, the chemical mechanical polishing apparatus includes a carrier head 1 for holding and rotating a wafer w, and a polishing pad 3 covered with a polishing pad 2. In the chemical mechanical polishing process, the carrier head 1 presses the wafer w against the polishing pad 2 covered on the surface of the polishing disk 3, the carrier head 1 rotates and reciprocates in the radial direction of the polishing disk 3, and simultaneously the polishing disk 3 rotates, so that the surface of the wafer w in contact with the polishing pad 2 is gradually polished away.
The eddy current sensor 10 provided by the embodiment of the invention is arranged below the disc surface of the polishing disc 3, the polishing pad 2 at the corresponding position above the eddy current sensor 10 is provided with the ground glass window 21, and the eddy current sensor 10 rotates along with the polishing disc 3 so as to realize online measurement while polishing.
As shown in fig. 8, the eddy current sensor 10 further includes an electromagnetic shielding case 13. The electromagnetic shielding shell 13 is a rectangular parallelepiped for accommodating the magnetic core 11 and the coil 12, and a certain gap is left between the electromagnetic shielding shell and the coil 12, so that electromagnetic interference in the environment can be shielded, and the magnetic field generated by the eddy current sensor 10 can penetrate through the upper region of the electromagnetic shielding shell as far as possible.
The electromagnetic shielding shell 13 is a multilayer structure, and a core layer of the electromagnetic shielding shell is made of a metal material, so that electromagnetic interference in the environment can be shielded, and a magnetic field generated by the eddy current sensor 10 can penetrate through an area above the electromagnetic shielding shell as far as possible; the surface of the electromagnetic shielding shell 13 is coated with a non-metallic material layer, which can prevent metal ions generated by the magnetic core 11, the coil 12 and the metal material in the core layer from diffusing to the production environment to cause metal pollution, thereby ensuring the accuracy of metal film thickness measurement and preventing the wafer surface from being scratched by metal pollutants and/or the metal pollutants from exceeding the standard in the chemical mechanical polishing process.
In one embodiment, the core layer of the electromagnetic shielding shell 13 is made of aluminum.
The non-metallic material layer of the electromagnetic shielding shell 13 is made of at least one material selected from plastic, ceramic and glass, and preferably, hard engineering plastic can be used. The hard engineering plastic can be hard polyvinyl chloride, polyethylene, organic glass, polypropylene, polystyrene, polytetrafluoroethylene, nylon, PET, ABS, PEEK and/or PPS. The thickness of the non-metallic material layer is 0.5mm-5 mm.
The eddy current sensor 10 further comprises an outer casing 14, the outer casing 14 being slotted near the edge for accommodating an electromagnetic shield 13 housing the magnetic core 11 and the coil 12. The encapsulating housing 14 is made of a transparent material, such as clear transparent plexiglass. As shown in fig. 8, the space on the left side of the package housing 14 is used for potting the eddy current sensor 10, and the space on the right side can be left for the optical inspection system, so that the laser light generated from below the package housing 14 can finally pass through the transparent package housing 14, the ground glass window 21 on the polishing pad 2, and irradiate on the wafer w to be inspected, and return to the receiver of the optical inspection system.
As shown in fig. 8, the eddy current sensor 10 is fitted into the region below the ground glass window 21 of the polishing pad 2 via the seal ring 15 and the groove on the polishing disk 3.
Fig. 9 shows the tracks and areas swept by the eddy current sensor 10 across the surface of the wafer w during polishing. The hatched area of a circular ring having a certain width in fig. 9 indicates the area scanned by the eddy current sensor 10. In the polishing process, the polishing disc 3 drives the eddy current sensor 10 and the wafer w to move relatively, and the mapping relation between the position of the swept area and the position of the surface of the wafer w is obtained through kinematic coordinate calculation, so that the shape distribution of the metal film thickness on the surface of the wafer w is obtained. It can be seen that compared to the conventional flat circular coil, the structure of the present application can obtain a wider range of metal film thickness information in the direction perpendicular to the radial direction when the diameter is the same as the width of the coil of the present application.
The drawings in the present specification are schematic views to assist in explaining the concept of the present invention, and schematically show the shapes of respective portions and their mutual relationships. It should be understood that the drawings are not necessarily to scale, the same reference numerals being used to identify the same elements in the drawings in order to clearly show the structure of the elements of the embodiments of the invention.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (7)
1. A metal film thickness measuring apparatus capable of preventing metal contamination, comprising:
an eddy current sensor including a magnetic core and a coil wound around an outer peripheral wall of the magnetic core in a circumferential direction of the magnetic core; the eddy current sensor further comprises an electromagnetic shielding shell, wherein a containing cavity for containing the magnetic core and the coil is defined in the electromagnetic shielding shell, a core layer of the electromagnetic shielding shell is made of a metal material, and the surface of the electromagnetic shielding shell is coated with a non-metal material layer so as to prevent metal ion pollution;
the preposed signal processing module is connected with the eddy current sensor and is used for inputting a sinusoidal excitation signal to the eddy current sensor and acquiring a voltage signal related to the thickness of the metal film through the eddy current sensor, wherein the frequency of the sinusoidal excitation signal is determined by the thickness range of the metal film to be measured and the type of the metal; the preposed signal processing module comprises a constant voltage source, a resonant capacitor and a divider resistor, wherein the divider resistor is connected with the eddy current sensor in parallel and then connected with the resonant capacitor and the constant voltage source in series;
the data acquisition processing module is connected with the preposed signal processing module and used for receiving the voltage signal output by the preposed signal processing module, converting the voltage signal into a digital signal and converting the digital signal into a corresponding film thickness value according to a prestored thickness calibration table;
and the communication module is used for realizing the communication between the data acquisition and processing module and the upper computer.
2. The metal film thickness measuring apparatus according to claim 1, wherein the resonance capacitance is calculated according to the following equation:
wherein f is0For a selected target excitation frequency, L is the inductance of the eddy current sensor, C is the capacitance of the resonant capacitor, and r is the internal resistance of the eddy current sensor.
3. The metal film thickness measuring apparatus according to claim 2, wherein the voltage dividing resistance takes a real part of impedance at both ends of the eddy current sensor at resonance.
4. The metal film thickness measuring apparatus according to claim 1, wherein said eddy current sensor further comprises an encapsulating case, said encapsulating case being provided with a groove for accommodating said electromagnetic shielding case in which said magnetic core and said coil are installed.
5. The metal film thickness measuring apparatus according to claim 1, wherein the magnetic core is a rectangular parallelepiped, the length of the magnetic core is 2 to 10 times its width, the width of the magnetic core is 2 to 4mm, and the height of the magnetic core is 1 to 3 mm; the coil is wound on the outer peripheral wall of the magnetic core along the circumferential direction of the cross section of the magnetic core, wherein the cross section is perpendicular to the height direction of the magnetic core.
6. The metal film thickness measuring apparatus according to claim 5, wherein the magnetic core material is a nickel zinc ferrite or a manganese zinc ferrite.
7. The metal film thickness measuring apparatus according to claim 5, wherein the coil is wound by an enameled copper wire having a diameter of 0.05mm to 0.2 mm.
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| WO2024078567A1 (en) * | 2022-10-14 | 2024-04-18 | 杭州众硅电子科技有限公司 | Eddy-current end-point detection apparatus and method |
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| CN114147622B (en) * | 2021-12-10 | 2023-04-07 | 北京晶亦精微科技股份有限公司 | CMP eddy current terminal detection device |
| CN114473844B (en) * | 2021-12-31 | 2023-09-29 | 华海清科股份有限公司 | Film thickness measuring device |
| CN114918820A (en) * | 2022-05-31 | 2022-08-19 | 北京烁科精微电子装备有限公司 | CMP (chemical mechanical polishing) end point detection device and method |
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| SU436276A1 (en) * | 1972-11-14 | 1974-07-15 | А. Я. Тетерко, В. Н. Учанин , П. П. Диегуц Физико механический институт Украинской ССР | CURRENT SWITCHING MODULATION SENSOR |
| CN102022971B (en) * | 2010-12-21 | 2012-12-19 | 清华大学 | Electric eddy sensor |
| CN102364850A (en) * | 2011-09-30 | 2012-02-29 | 深圳麦格米特电气股份有限公司 | Method for inhibiting overvoltage and overcurrent of resonant transformation circuit and resonant transformation circuit |
| CN102564287B (en) * | 2011-12-15 | 2014-07-16 | 清华大学 | Method for measuring film thickness of wafer by using wafer platform |
| CN102538655B (en) * | 2012-01-09 | 2014-04-09 | 清华大学 | Device and method for measuring thickness of conductor membrane |
| CN206192369U (en) * | 2016-10-19 | 2017-05-24 | 珠海格力节能环保制冷技术研究中心有限公司 | Electric eddy sensor |
| CN107121153A (en) * | 2017-05-22 | 2017-09-01 | 天津大学 | High speed current vortex sensor |
| CN206832179U (en) * | 2017-06-02 | 2018-01-02 | 深圳怡化电脑股份有限公司 | A kind of electric vortex sensor measuring circuit and current vortex sensor |
| CN207197432U (en) * | 2017-07-14 | 2018-04-06 | 深圳宇问加壹传感系统有限公司 | Eddy current effect thickness transducer |
| CN110524412A (en) * | 2019-09-30 | 2019-12-03 | 清华大学 | A kind of Retaining Ring in Chemical Mechanical Polishing Process and chemically mechanical polishing carrier head |
| CN213932356U (en) * | 2020-12-30 | 2021-08-10 | 清华大学 | Metal film thickness measuring device for CMP |
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