1. A low-temperature solid dielectric constant measuring method tests the dielectric constant of a solid in a mode of combining in-situ capacitance test and low-temperature deformation simulation, and is characterized by comprising the following steps of:

providing a flat capacitor, wherein the flat capacitor comprises a first polar plate, a solid dielectric layer and a second polar plate which are sequentially overlapped;

providing a testing device, wherein the testing device comprises a testing cavity, placing the flat capacitor in the testing cavity, and cooling to a testing temperature;

providing a capacitance measuring instrument which is respectively electrically connected with the first polar plate and the second polar plate so as to measure the capacitance value of the plate capacitor at the test temperature;

performing thermal stress simulation on the plate capacitor, and simulating deformation of the plate capacitor caused by temperature change in the cooling process through solid modeling;

and carrying out data processing by combining the capacitance value and the deformation amount to obtain the dielectric constant of the solid dielectric layer at the test temperature.

2. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: the test temperature is below 77K.

3. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: the cooling mode of the testing device comprises liquid helium cooling or compressor cooling.

4. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: the testing device comprises a low-temperature probe station.

5. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: the method for measuring the capacitance value of the plate capacitor comprises a Kelvin four-probe method; the capacitance measuring instrument comprises a precision capacitance measuring instrument suitable for semiconductor device measurement.

6. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: the flat capacitor comprises a first metal polar plate, a solid dielectric layer and a second metal polar plate which are sequentially stacked.

7. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: the plate capacitor further comprises a first metal connecting layer and a first metal contact pad which are electrically connected with the first plate, and a second metal connecting layer and a second metal contact pad which are electrically connected with the second plate.

8. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: more than 2 different flat capacitors are placed in the test cavity.

9. The method for measuring dielectric constant of a low-temperature solid according to claim 1, wherein: the flat capacitor is prepared in situ on a substrate by a microelectronic process.

10. The method for measuring the dielectric constant of the low-temperature solid according to claim 1, wherein when the plate capacitor is a square plate capacitor with a plate side length a, and the capacitance value at the test temperature obtained by the in-situ capacitance test is C, the change of the plate side length caused by the temperature difference change obtained by the thermal stress simulation is delta a, and the change of the thickness of the solid dielectric layer is delta h, the deformation quantity is added in the data processing to correct the calculation formula of the dielectric constant of the low-temperature solid, and the calculation formula is as follows: e ═ C (h + Δ h)/(a + Δ a)²。

Background

The dielectric constant is an important characteristic parameter for describing the electromagnetic property of the material, has an important role in the fields of material science, microwave engineering, electromagnetism and the like, and is a fundamental and important subject for accurately measuring the dielectric constant. Among them, the methods for measuring the dielectric constant of a solid at room temperature and low frequency include a capacitance method, a bridge method, a resonant tank method, a vector impedance method, and the like, but in some special low-temperature fields (such as the superconducting field), the dielectric constant of a material in a low-temperature environment is often required to be known. Due to the particularity of the low-temperature environment, new challenges are provided for the method for measuring the dielectric constant, such as how to measure required parameters in the low-temperature environment, how to solve the problem of material deformation caused by the low-temperature environment, and the like.

Therefore, it is necessary to provide a method for measuring the dielectric constant of a low-temperature solid.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a low-temperature solid dielectric constant measuring method for solving the problem of the prior art that it is difficult to obtain a solid dielectric constant by low-temperature measurement.

In order to achieve the above objects and other related objects, the present invention provides a method for measuring dielectric constant of a low temperature solid, which adopts a combination of in-situ capacitance test and low temperature deformation simulation to test the dielectric constant of the solid, and comprises the following steps:

providing a flat capacitor, wherein the flat capacitor comprises a first polar plate, a solid dielectric layer and a second polar plate which are sequentially overlapped;

providing a testing device, wherein the testing device comprises a testing cavity, placing the flat capacitor in the testing cavity, and cooling to a testing temperature;

providing a capacitance measuring instrument which is respectively electrically connected with the first polar plate and the second polar plate so as to measure the capacitance value of the plate capacitor at the test temperature;

performing thermal stress simulation on the plate capacitor, and simulating deformation of the plate capacitor caused by temperature change in the cooling process through solid modeling;

and carrying out data processing by combining the capacitance value and the deformation amount to obtain the dielectric constant of the solid dielectric layer at the test temperature.

Optionally, the test temperature is 77K or less.

Optionally, the cooling mode of the testing device includes liquid helium cooling or compressor cooling.

Optionally, the testing device comprises a cryogenic probe station.

Optionally, the method for measuring the capacitance value of the plate capacitor comprises a kelvin four-probe method; the capacitance measuring instrument comprises a precision capacitance measuring instrument suitable for semiconductor device measurement.

Optionally, the plate capacitor includes a first metal plate, a solid dielectric layer, and a second metal plate stacked in sequence.

Optionally, the plate capacitor further includes a first metal connection layer and a first metal contact pad electrically connected to the first plate, and a second metal connection layer and a second metal contact pad electrically connected to the second plate.

Optionally, more than 2 different flat capacitors are placed in the test chamber.

Optionally, the plate capacitor is fabricated in situ on the substrate by microelectronic processes.

Optionally, when the flat capacitor is a square flat capacitor with a plate side length a, and a capacitance value C is obtained at a test temperature through an in-situ capacitance test, a change in the plate side length due to a temperature difference change is Δ a through thermal stress simulation, and a change in the solid dielectric layer thickness is Δ h, the deformation is added to the data processing to correct the low-temperature solid dielectric constant calculation formula as follows: e ═ C (h + Δ h)/(a + Δ a)²。

As described above, in the low-temperature solid dielectric constant measuring method of the present invention, the testing device is used to cool the plate capacitor having the solid medium to be measured to reach the testing temperature, the capacitance measuring instrument is used to measure the capacitance value of the plate capacitor at the testing temperature, and the thermal stress simulation is used to perform the solid modeling, so as to simulate the deformation of the plate capacitor caused by the temperature change during the cooling process, thereby performing the data processing by combining the capacitance value and the deformation, and obtaining the dielectric constant of the solid medium layer at the testing temperature. The method can accurately test the dielectric constant of the solid dielectric layer in a low-temperature environment by combining in-situ capacitance measurement and low-temperature deformation simulation, is simple and convenient, and is feasible in the low-temperature environment; the capacitance value is measured by adopting a Kelvin four-probe method, so that the contact resistance of a test probe and a contact pad and the influence of the line resistance of a capacitance measuring instrument on a measuring result can be removed, the test accuracy can be further improved, and the test error is reduced; carrying out solid modeling simulation through finite element thermal stress simulation software to evaluate the deformation of the plate capacitor caused by low temperature so as to enable the calculation of the dielectric constant of the low-temperature solid to be more accurate; a plurality of groups of capacitance values can be obtained by designing a plurality of groups of plate capacitors with different dimensions, and measurement errors can be further reduced through data processing.

Drawings

FIG. 1 is a schematic flow chart of the method for measuring dielectric constant of low temperature solid according to the present invention.

FIG. 2 is a schematic structural diagram illustrating the measurement of the dielectric constant of the low-temperature solid according to the embodiment of the present invention.

Fig. 3 is a schematic top view of a plate capacitor according to an embodiment of the invention.

Fig. 4 is a schematic cross-sectional structure diagram of a plate capacitor according to an embodiment of the invention.

Description of the element reference numerals

100 plate capacitor

200 testing device

300 probe

400 capacitance measuring instrument

101 substrate

102 polar plate

103 solid dielectric layer

104 metal connection layer

105 metal contact pad

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. As used herein, "between … …" is meant to include both endpoints.

In the context of this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed freely, and the layout of the components may be more complicated.

As shown in fig. 1, the present embodiment provides a method for measuring a dielectric constant of a low-temperature solid, which adopts a combination of an in-situ capacitance test and a low-temperature deformation simulation to test the dielectric constant of the solid, and includes the following steps:

s1: providing a flat capacitor, wherein the flat capacitor comprises a first polar plate, a solid dielectric layer and a second polar plate which are sequentially overlapped;

s2: providing a testing device, wherein the testing device comprises a testing cavity, placing the flat capacitor in the testing cavity, and cooling to a testing temperature;

s3: providing a capacitance measuring instrument which is respectively electrically connected with the first polar plate and the second polar plate so as to measure the capacitance value of the plate capacitor at the test temperature;

s4: performing thermal stress simulation on the plate capacitor, and simulating deformation of the plate capacitor caused by temperature change in the cooling process through solid modeling;

s5: and carrying out data processing by combining the capacitance value and the deformation amount to obtain the dielectric constant of the solid dielectric layer at the test temperature.

According to the method for measuring the dielectric constant of the low-temperature solid, the testing device is used for cooling the flat capacitor to reach the testing temperature, the capacitance measuring instrument is used for measuring the capacitance value of the flat capacitor at the testing temperature, the thermal stress simulation software is used for carrying out solid modeling and simulating the deformation quantity of the flat capacitor caused by temperature change in the cooling process, so that data processing is carried out by combining the capacitance value and the deformation quantity, and the dielectric constant of the solid dielectric layer at the testing temperature can be obtained. In the embodiment, the dielectric constant of the solid dielectric layer in a low-temperature environment can be accurately tested by combining in-situ capacitance measurement and low-temperature deformation simulation, and the testing method is simple and feasible in the low-temperature environment.

It should be noted that the sequence of the above steps can be adaptively changed according to the needs, and the method for measuring the dielectric constant of the low temperature solid in this embodiment is described below with reference to fig. 2 to 4.

First, referring to fig. 3 and 4, step S1 is executed to provide a plate capacitor 100, where the plate capacitor 100 includes a first plate, a solid dielectric layer 103, and a second plate stacked in sequence.

Specifically, in this embodiment, the plate capacitor 100 is adopted as a sample to be measured, the plate capacitor 100 includes plates 102 and a solid dielectric layer 103 located between the plates 102, and in the plate capacitor 100, parameters affecting a capacitance value C of the plate capacitor 100 are a thickness h and a dielectric constant ∈ of the solid dielectric layer 103 and a length and a width of the plate 102, respectively.

Preferably, in this embodiment, in order to reduce the calculation complexity, the plate 102 is designed to be a square structure, that is, the first plate and the second plate are square with a side length of a, and then C ═ epsilon · a can be obtained according to the capacitance calculation formula²H, the dielectric constant of the solid dielectric layer 103 can be calculated by the formula ∈ ═ C · h/a²However, the shape of the plate 102 is not limited to this, and may be set according to the requirement.

By way of example, the plate capacitor 100 includes a first niobium plate, a silicon dioxide dielectric layer, and a second niobium plate stacked in this order. In this embodiment, the plate 102 is a niobium plate, and the solid dielectric layer 103 is a silicon dioxide dielectric layer, but the invention is not limited thereto, and the type of the plate capacitor 100 may be set as required.

Further, the panel capacitor 100 may further include a first metal connection layer and a first metal contact pad electrically connected to the first plate, and a second metal connection layer and a second metal contact pad electrically connected to the second plate.

Specifically, as shown in fig. 3 and 4, in the present embodiment, the plate capacitor 100 includes a metal connection layer 104 and a metal contact pad 105 electrically connected to the plate 102, so as to be electrically connected to a probe 300 in a contact manner through the metal contact pad 105 for testing. The materials of the metal connection layer 104 and the metal contact pad 105 may be the same as the materials of the plate 102, so as to reduce the complexity of the manufacturing process, for example, the plate 102, the metal connection layer 104 and the metal contact pad 105 may include but are not limited to a superconducting metal, and preferably, in this embodiment, the plate 102, the metal connection layer 104 and the metal contact pad 105 are made of niobium metal.

As an example, the plate capacitor 100 is fabricated in situ on the substrate 101 by microelectronic processes.

Specifically, in this embodiment, the plate capacitor 100 is prepared and formed on the substrate 101, wherein the substrate 101 may include but is not limited to a silicon wafer, and preferably, in this embodiment, the substrate 101 is a silicon wafer with a <100> crystal orientation. The method for fabricating the plate capacitor 100 on the substrate 101 is not limited herein.

Next, referring to fig. 2, step S2 is executed to provide a testing apparatus 200, where the testing apparatus 200 includes a testing chamber, the plate capacitor 100 is placed in the testing chamber, and the testing temperature is reduced to a testing temperature.

As an example, the test temperature may be below 77K, and the test temperature may be 70K, 50K, 20K, 10K, 4.2K, 2mK, or the like, and may be specifically set as needed.

By way of example, the test apparatus 200 may include a cryogenic probe station; the cooling method of the testing device 200 includes liquid helium cooling or compressor cooling.

Specifically, in the present embodiment, the test apparatus 200 is a low temperature probe station, but the specific type of the test apparatus is not limited thereto, and can be selected as needed. Wherein, the mode that testing arrangement 200 cooled down can include liquid helium cooling or compressor cooling, in this embodiment, the low temperature probe platform adopts sealed and evacuation back, treats the interior vacuum degree of low temperature probe platform lets in liquid helium cooling after reaching certain degree, until the stable test environment at microthermal of temperature in the low temperature probe platform. In this embodiment, the liquid helium is used for cooling, so that the temperature is maintained at 4.2K, and other cooling methods, such as a compressor, can be used for cooling, so as to achieve different low temperature environments to achieve the measurement of the dielectric constant at different temperatures, which is not limited herein.

Next, referring to fig. 2, step S3 is executed to provide a capacitance measuring instrument 400, where the capacitance measuring instrument 400 is electrically connected to the first plate and the second plate respectively to measure a capacitance value C of the plate capacitor 100 at the testing temperature.

Specifically, the capacitance measuring instrument 400 may be electrically connected to the plate 102 of the plate capacitor 100 through the probe 300, so as to obtain a capacitance value C corresponding to the plate capacitor 100 in a low-temperature testing environment through the capacitance measuring instrument 400. In this embodiment, the probes 300 are connected to the capacitance measuring instrument 400 through cables, and the probes 300 are respectively stuck on the metal contact pads 105, so as to obtain the capacitance value C of the solid dielectric layer 103 at the testing temperature by reading the capacitance value measured by the capacitance measuring instrument 400. The probe 300 may include, but is not limited to, a low temperature direct current probe.

As an example, the method for measuring the capacitance value of the plate capacitor 100 includes a kelvin four-probe method.

Specifically, as shown in fig. 2, in the present embodiment, the kelvin four-probe method is used to measure the plate capacitor 100, so that the contact resistance between the probe 300 and the metal contact pad 105 and the influence of the wire resistance of the capacitance measuring apparatus 400 on the measurement result can be removed, and the test accuracy can be further improved.

The capacitance measuring instrument 400 includes a precision capacitance measuring instrument suitable for semiconductor device measurement, as an example, to improve the test accuracy, but the kind of the capacitance measuring instrument 400 is not limited thereto.

Next, step S4 is executed to provide thermal stress simulation software, and the thermal stress simulation software performs solid modeling to simulate the deformation of the plate capacitor 100 caused by temperature change during the cooling process.

As an example, the thermal stress simulation software comprises finite element thermal stress simulation software.

In particular, the finite element thermal stress is imitatedThe true software can simulate the deformation of the parallel plate capacitor 100 due to the cooling effect, for example, in this embodiment, the side length of the parallel plate capacitor 100 is changed to Δ a, the thickness is changed to Δ h, and C ═ ε · a²The formula for calculating the corrected dielectric constant obtained from the relationship of/h is: e ═ C (h + Δ h)/(a + Δ a)². Therefore, the dielectric constant of the solid dielectric layer 103 in a low-temperature environment can be tested by combining in-situ capacitance measurement and low-temperature deformation simulation, and the testing method is simple and feasible in the low-temperature environment.

Further, more than 2 different plate capacitors 100 may be placed in the test chamber.

Specifically, when more than 2 different flat capacitors 100 are placed in the test chamber, for example, parallel plate capacitors with different side lengths a and different thicknesses h are designed, a plurality of groups of capacitance values C can be measured at a low temperature, and C ═ epsilon (a + Δ a)²/(h + Δ h) relationship obtaining C and (a + Δ a)²The dielectric constant ε can be obtained by obtaining the slope by fitting the change map of (a), and multiplying the thickness (h + Δ h) by the slope. Multiple sets of parallel plate capacitors 100 having different thicknesses can yield multiple sets of values of dielectric constant epsilon that, on average, can improve measurement accuracy. Of course, more than 2 identical plate capacitors 100 can be placed in the test chamber to obtain multiple sets of dielectric constants epsilon and then average, which can also improve the measurement accuracy.

In summary, in the low-temperature solid dielectric constant measuring method of the present invention, the testing device is used to cool the plate capacitor with the solid medium to be measured to reach the testing temperature, the capacitance measuring instrument is used to measure the capacitance of the plate capacitor at the testing temperature, and the thermal stress simulation is used to perform the solid modeling, so as to simulate the deformation of the plate capacitor caused by the temperature change during the cooling process, thereby performing the data processing by combining the capacitance and the deformation, and obtaining the dielectric constant of the solid medium layer at the testing temperature. The method can accurately test the dielectric constant of the solid dielectric layer in a low-temperature environment by combining in-situ capacitance measurement and low-temperature deformation simulation, is simple and convenient, and is feasible in the low-temperature environment; the capacitance value is measured by adopting a Kelvin four-probe method, so that the contact resistance of a test probe and a contact pad and the influence of the line resistance of a capacitance measuring instrument on a measuring result can be removed, the test accuracy can be further improved, and the test error is reduced; carrying out solid modeling simulation through finite element thermal stress simulation software to evaluate the deformation of the plate capacitor caused by low temperature so as to enable the calculation of the dielectric constant of the low-temperature solid to be more accurate; a plurality of groups of capacitance values can be obtained by designing a plurality of groups of plate capacitors with different dimensions, and measurement errors can be further reduced through data processing.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.