CN115060745A - Microwave array sensor and manufacturing method thereof - Google Patents
Microwave array sensor and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses a microwave array sensor and a manufacturing method thereof. The device comprises a microwave resonance array, a port switch array and a variable capacitance diode array, wherein each measuring point on an article is represented by the position of each unit in the microwave resonance array, and the microwave resonance array is utilized to obtain microwave parameters of each point so as to realize the representation of physical information of the article; the microwave frequency of each resonance unit is controlled by using the variable capacitance diodes, the working state of each resonance unit is controlled, the working state of each array unit is controlled by the variable capacitance diodes arranged on two sides of each transmission line and the radio frequency switches arranged at two ports of the transmission line, the working independence of each array unit is ensured, the anti-interference capability is enhanced, the problem of time-sharing multiplexing of the array units is solved, and the detection precision is further improved.
Description
Technical Field
The invention relates to the field of radio frequency sensors, in particular to a microwave array type sensor and a manufacturing method thereof.
Background
An Atomic Force Microscope (AFM) is one of the typical material characterization methods in the prior art, which can provide a true three-dimensional surface map, and the AFM does not need any special treatment on the sample, such as copper plating or carbon, so that the special treatment can avoid irreversible damage to the sample. Thus, AFM can be used to study biological macro molecules, even living biological tissues. However, the AFM still has inevitable problems, such as slow imaging speed, large influence of the probe, limited working area, scanning in the micrometer scale range, difficulty in scanning the surface of a large or rough sample, and the like. Thus, when the scanning range is in the mm or even cm level, or the material grain size is in the μm level, or the material surface fluctuation is large, the AFM is not applicable.
The microwave array sensor can well solve the problems as a novel array form, and the scattering parameters of the microwave array are used for expressing physical parameters such as surface morphology, thickness, dielectric property and the like of a sample. The traditional microwave resonance array consists of resonance units and transmission lines, wherein the transmission lines feed the resonance units in a coupling mode, the resonance units work independently, the scanning range of a sample is determined by the array scale, and non-invasive detection can be realized in the sensing range of a resonator.
However, the application of the microwave array structure to material characterization will also bring new problems. Conventional microwave arrays can provide dielectric information at different locations in a two-dimensional plane, where different resonant cells are typically designed at different resonant frequencies. Therefore, the resonance units can work independently at the same time, namely, the work of each resonance unit in the same time period is not interfered with each other, and the resonance modes with different frequencies can represent the physical parameters of samples at different positions. However, in order to more accurately characterize the physical parameters of the material, the array element distribution density and range need to be increased, and the conventional array scale is limited by the array element structure and harmonics.
As the number of resonant units increases, the resonant units with fundamental waves in the low frequency band generate harmonic waves at high frequency, and the harmonic waves at high frequency generate crosstalk with the fundamental waves of the high frequency units, so that the available frequency spectrum range greatly limits the array size. In addition, the physical sizes of the low-frequency unit and the high-frequency unit are greatly different, and the detection range of samples of different units is different, so that the characterization and integration are not facilitated. If the resonant units are designed to have the same physical size, microwave response parameters generated by all the units are the same, which will cause mutual interference of the resonant units during operation, thereby affecting the article detection result.
Therefore, in summary, the problem that how to guarantee independent operations of different array elements while keeping the structure of the resonant unit uniform and how to avoid mutual interference of electromagnetic radiation between adjacent array elements needs to be solved.
Disclosure of Invention
The invention aims to provide a microwave array sensor and a manufacturing method thereof, and aims to solve the problems of how to ensure independent work of different array elements and avoid mutual interference of adjacent units when the unit structure is kept uniform.
In order to solve the above technical problem, the present invention provides a microwave array sensor, including:
microwave resonance array: the microwave scattering parameter measuring device comprises mxn resonance units and m/2 transmission lines which are arranged in parallel, wherein the upper side and the lower side of each transmission line in the vertical direction of the transmission lines are respectively connected with the n resonance units, each resonance unit is used as a measuring point of an object to be measured, and the microwave scattering parameter of the object to be measured at each measuring point is obtained through a generated resonance frequency signal so as to realize the representation of physical information of the object to be measured;
varactor array: the microwave resonant array is used for fixing the resonant frequency of the microwave resonant array and comprises mxn variable capacitance diodes, each variable capacitance diode is arranged between one resonant unit and a transmission line connected with the resonant unit, two ends of each variable capacitance diode are connected with control circuits, the control circuits are used for adjusting bias voltages at two ends of each variable capacitance diode so as to adjust the capacitance value of each variable capacitance diode, and the resonant frequency of the resonant unit connected with the variable capacitance diodes is adjusted by adjusting the capacitance value;
port switch array: the microwave resonance array is used for controlling the transmission of resonance frequency signals generated by the microwave resonance array, the left port and the right port of each transmission line are respectively connected with one radio frequency switch, and the two radio frequency switches connected with the transmission lines are simultaneously turned on or off to control the corresponding transmission lines to carry out signal transmission.
Preferably, the controlling, by turning on or off of the two radio frequency switches connected by the transmission line, the corresponding transmission line to perform signal transmission includes:
and sequentially controlling two radio frequency switches connected on the ith (i is 1,2, …, m/2) transmission line to be simultaneously turned on and off until the transmission of the resonance frequency signals generated by the resonance units on all the transmission lines is completed.
Preferably, the radio frequency switch is connected with a vector network analyzer, and the vector network analyzer is used for receiving the resonant frequency signals of the resonant units transmitted by the transmission line.
Preferably, the radio frequency switch is connected with a multiplexing controller, and the multiplexing controller is used for controlling the on and off of the radio frequency switch;
the radio frequency switches connected with the left ports of all the transmission lines are connected with the first multiplexing controller together, and the radio frequency switches connected with the right ports of all the transmission lines are connected with the second multiplexing controller together.
Preferably, the resonance units are open resonance rings, and each resonance unit has the same physical size.
The invention also provides a manufacturing method of the microwave array sensor, which comprises the following steps:
providing a cleaned and dried substrate;
preparing a first SiO on the upper surface of the substrate 2 Layer on the first SiO 2 Growing a first seed metal layer on the upper surface of the layer;
preparing a microwave resonance array layer on the upper surface of the first sub-metal layer, wherein a plurality of transmission lines are arranged in the microwave resonance array layer at equal intervals in parallel, a plurality of resonance units are arranged at equal intervals on two sides of each transmission line in the vertical direction of the transmission lines, and the position of a variable capacitance diode is reserved between each transmission line and each resonance unit;
preparing a second SiO on the lower surface of the substrate 2 Layer on the second SiO 2 Growing a second seed metal layer on the lower surface of the layer;
preparing a ground metal layer on the lower surface of the second seed metal layer, and generating a third SiO on the lower surface of the ground metal layer 2 A layer;
in the third SiO 2 Growing a third sub-metal layer on the lower surface of the layer, and preparing a varactor voltage control layer on the lower surface of the third sub-metal layer;
and each variable capacitance diode is arranged at a reserved position between the transmission line and each resonant unit, one end of each variable capacitance diode is connected with the grounding metal layer, and the other end of each variable capacitance diode is connected with the variable capacitance diode voltage control layer.
Preferably, the reserving of the varactor diode between the transmission line and each resonant cell includes:
determining the distance between adjacent transmission lines according to the preset harmonic amplitude value and the number of the preset transmission lines, and parallelly arranging the transmission lines according to the distance between the adjacent transmission lines;
determining the distance between the resonant unit and the connected transmission line according to the preset harmonic amplitude value, and determining the distance between adjacent resonant units according to the preset harmonic amplitude value and the number of the preset resonant units;
according to the distance between the resonant unit and the connected transmission line and the distance between the resonant units and the adjacent resonant units, arranging a plurality of resonant units on two sides of each transmission line along the vertical direction of the transmission line;
and taking the central positions of the transmission line and each resonant unit as reserved varactor diode positions.
Preferably, the preset harmonic amplitude value is not greater than 3 dB.
Preferably, the first SiO 2 Layer, second SiO 2 Layer and third SiO 2 The layers are all prepared by adopting a chemical vapor deposition process;
the first seed metal layer, the second seed metal layer, the third seed metal layer and the voltage control layer of the variable capacitance diode are all prepared by adopting an evaporation process;
the microwave resonance array layer and the grounding metal layer are prepared by adopting an electroplating process.
Preferably, the left and right ports of the transmission line of the microwave resonance array layer are led out by a jumper to be connected with the radio frequency switch.
The invention provides a microwave array sensor which comprises a microwave resonance array, a port switch array and a variable capacitance diode array, wherein each measuring point on an article is represented by the position of each unit in the microwave resonance array, and the microwave resonance array is utilized to obtain microwave parameters of each point so as to realize the representation of physical information of the article; the resonance frequency of each resonance unit, namely the working state of each resonance unit, is controlled by controlling the capacitance value of the variable capacitance diode, and the signal transmission of the transmission line is controlled by utilizing the radio frequency switch connected with the two ports of the transmission line, so that the independent work of each resonance unit is realized, the electromagnetic radiation interference between adjacent units is avoided, the anti-interference capability between the units is enhanced, and the detection precision of the material form can be further improved.
Drawings
In order to more clearly illustrate the embodiments or technical solutions of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a block diagram of one embodiment of a microwave array sensor provided in the present invention;
fig. 2 is a schematic view of a working mode 1 of a microwave array sensor according to an embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a microwave array sensor according to an embodiment of the present invention;
fig. 4 is a schematic view of an operation mode 2 of the microwave array sensor according to the embodiment of the present invention;
fig. 5 is a schematic diagram of a working mode 3 of the microwave array sensor according to the embodiment of the present invention;
fig. 6 is a simulation diagram of a microwave array sensor according to an embodiment of the present invention;
wherein: 1-a silicon substrate; 2-first SiO 2 A layer; 3-a first seed metal layer; 4-a microwave resonant array layer; 5-second SiO 2 A layer; 6-a second seed metal layer; 7-ground plane metal layer; 8-third SiO 2 A layer; 9-a third sub-metal layer; 10-a varactor voltage control layer; 11-a varactor diode; 12-varactor via.
Detailed Description
The core of the invention is to provide a microwave array sensor and a manufacturing method thereof, and the microwave array sensor is adopted to represent the form of a substance. Through the variable capacitance diodes arranged on two sides of each transmission line and the radio frequency switches arranged at two ports of the transmission line, the working state of each resonance unit is controlled, the working independence of each resonance unit is ensured, the anti-interference capability is enhanced, and the detection precision is further improved.
In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. 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.
The invention provides a microwave array sensor, which comprises a microwave resonance array, a port switch array and a variable capacitance diode array, wherein the microwave resonance array is connected with the port switch array;
microwave resonance array: the resonant frequency generating device is used for generating resonant frequency and comprises m multiplied by n resonant units, m/2 mutually parallel transmission lines, and n resonant units are respectively connected to the upper side and the lower side of each transmission line along the vertical direction of the transmission lines;
varactor array: the microwave resonant array comprises mxn variable capacitance diodes, each variable capacitance diode is arranged between one resonant unit and an adjacent transmission line, two ends of each variable capacitance diode are connected with a control circuit, the control circuits are used for adjusting bias voltages at two ends of the variable capacitance diodes so as to adjust capacitance values of the variable capacitance diodes, and the resonant frequency of the resonant unit connected with the variable capacitance diodes is adjusted by adjusting the capacitance values;
a port switch array: the device is used for controlling m/2 resonance units in the microwave resonance array to work independently and comprises m ports, each transmission line is provided with two ports, and each port is connected with a radio frequency switch;
all the resonance units (m rows and n columns) are arranged on the same horizontal plane in parallel, and an object is directly placed above the resonance units when the object to be measured is measured.
Referring to fig. 1, fig. 1 shows a specific structure diagram of a microwave array sensor provided in the present embodiment;
the microwave resonance array comprises m multiplied by n resonance units and m/2 transmission lines; the port switch array comprises m ports; the varactor array comprises m × n varactors; 2n resonance units are distributed on two sides of each transmission line to form an array unit; each resonance unit is connected with the transmission lines through diodes, ports at two ends of each transmission line are connected with the radio frequency switches, the radio frequency switches are m radio frequency switches in total, and the radio frequency switches are further connected with the multiplexers. All the transmission lines are arranged in parallel at equal intervals, the resonance units on the same horizontal line are also arranged at equal intervals, and the distance between each resonance unit and the transmission line connected with the resonance unit is equal.
The resonant units are classical metamaterial structures, namely open resonant rings (SRRs), can be equivalently LC resonance in work, provide resonant modes with high Q values and high amplitude values at the cost of small area, have the same physical size and work at the same resonant frequency, and physical parameters of a sample are represented by microwave parameters, so that the problem of limitation of available frequency spectrums of a traditional microwave resonant array sensor is solved.
In order to solve the problem that the resonant cells do not work independently, the present embodiment solves the problem by using a port switch array and a varactor array. The port switch array is composed of radio frequency switches and control circuits thereof, each transmission line port is connected with the vector network analyzer through one radio frequency switch, all the radio frequency switches are connected with the same vector network analyzer, the opening and closing of the radio frequency switches are controlled by a multiplexer, and the time-sharing multiplexing of the transmission lines can be controlled through the multiplexer. The varactor array is composed of varactors and a control circuit thereof, and a certain distance (standard is that the harmonic amplitude value is below 3dB) is firstly kept between the array and the transmission line so as to avoid the coupling between the feeder line and the resonance unit and the interference of the coupling between the resonance unit and the resonance unit to the resonance unit. The loaded varactor diode then connects the transmission line to the resonant cell, and its capacitance is changed by applying a reverse voltage across the diode, thereby controlling the operating state of the resonant cell. The distance between two adjacent resonance units, the distance between the resonance units and the transmission line and the distance between the resonance units on two adjacent transmission lines all meet the requirement that the harmonic amplitude value is below 3 dB. According to a preset harmonic amplitude value (if the preset harmonic amplitude value is 3dB), a first set threshold value (the distance between adjacent resonance units in the microwave resonance array along the transmission line direction), a second set threshold value (the distance between the resonance units and the transmission line connected with the resonance units), and a third set threshold value (the distance between the adjacent resonance units between two adjacent transmission lines) are determined, the problem of mutual interference caused by distance factors is solved through the set threshold values, and the harmonic amplitude value of each resonance unit in the finally laid microwave resonance array is below 3 dB. When the distance is farther, the harmonic amplitude value is lower, and meanwhile, whether the resonance amplitude value can represent points on the object to be measured or not is considered in the arrangement process, namely whether the arranged distance can reasonably correspond to each point on the sample to be measured or not is considered, so that a good measurement result is achieved, and therefore the number of the transmission lines and the number of the resonance units are also considered.
In this embodiment, the mxn resonant units correspond to mxn detection points of a sample to be detected, and when scanning a resonant unit corresponding to a certain detection point, the transmission line in the row is first connected to a VNA (vector network analyzer) through a radio frequency switch, and then a reverse voltage is applied to the varactor diode connected to the resonant unit for conduction, and the physical information of the detection point can be obtained after data analysis is performed on the obtained microwave parameters. When the planar resonant array starts to work, firstly, the radio frequency switch of the first transmission line is started, then the 2n resonant units connected with the first transmission line are respectively conducted, after the scanning is finished, the radio frequency switch of the second transmission line is started, then the 2n resonant units connected with the second transmission line are respectively conducted, and the rest is done, and the scanning information of the whole planar resonant array is finally obtained. In addition, because the feeder line has an inductance effect, different equivalent inductances are brought by unequal lengths of the feeder lines connected with the resonance units, and thus differences of microwave parameters of the resonance units are caused, the solution is to change capacitance values of the variable capacitance diodes to make up for errors caused by the device design, the two ends of the variable capacitance diodes are connected with control circuits, the capacitance values can be adjusted by adjusting bias voltages at the two ends of the variable capacitance diodes, so that equivalent lengths of transmission lines of the resonance units at different positions are the same, the resonance frequency of the resonator is maintained at a fixed value (the fixed value in the embodiment is 6GHz), and meanwhile, the variable capacitance diodes can also make up for drift of the microwave parameters after long-time use; referring to the die data in the microwave parametric simulation diagram in fig. 3, it can be seen that the resonant frequency of the die is maintained at 6 GHz.
The loaded variable capacitance diode in the embodiment of the invention has multiple beneficial effects, not only ensures that each resonance unit works independently to provide physical parameters of a sample at a certain detection point, but also can compensate the inductance effect of a transmission line, and simultaneously reduces the dynamic power consumption of the whole array. Besides, the array sensor scale is limited only by the control circuit wiring, and besides the diode control circuit, the array sensor scale simplifies the port control circuit and realizes further array scale enlargement. The specific scheme is that the resonance units are distributed on two sides of the transmission line, and the number of the transmission lines is reduced by half on the premise that the number of the resonance units is certain, so that the requirements for the radio frequency switch and the corresponding control circuit are reduced. The enlargement of the array size represents a further improvement in the detection accuracy of the array sensor.
In the actual test process, firstly, an object to be tested is introduced into the microwave resonance array, then the radio frequency switch starts to work, and m/2 transmission lines are sequentially connected into the circuit.
When one transmission line is connected into the circuit, the variable capacitance diode scanning circuit starts to work, reverse voltage is applied to two ends of the variable capacitance diode, the variable capacitance diodes are conducted in sequence, and 2n resonator units are controlled to work in sequence. And finally, completing scanning of all detection points and recording S parameters.
Taking the first row of microwave resonant array as an example (refer to fig. 1), first, two rf switches of the control array 1 (the first transmission line) are turned on, then two ends of the transmission line are connected to VNA, then reverse voltages are applied to two ends of varactors of the resonant unit 11, the resonant unit 12, the resonant units 13 and … …, the resonant unit 1n, the resonant unit 21, the resonant units 22 and … …, and the resonant unit 2n in sequence, so that 2n resonant units are controlled to start to operate sequentially, and the display result of VNA shows that the resonant modes are shifted to different degrees. Finally, processing the measurement result, converting the frequency movement into physical information of the sample, and integrating 2n detection results; after the first transmission line finishes data transmission, the radio frequency switches connected with the left end and the right end of the first transmission line are closed;
then, the two rf switches of the control array 2 (the second transmission line) are turned on, then the two ends of the transmission line of the array 2 are connected to the VNA, and then reverse voltages are sequentially applied to the two ends of the varactor diodes of the resonant unit 31, the resonant unit 32, the resonant units 33 and … …, the resonant unit 3n, the resonant unit 41, the resonant units 42 and … …, and the resonant unit 4n, so that the 2n resonant units are controlled to start to operate sequentially, and the display result of the VNA shows that the resonant modes are shifted to different degrees. And finally, processing the measurement result, converting the frequency movement into physical information of the sample, and integrating the 2n detection results.
And repeating the process until all the transmission lines and the array units are scanned, and analyzing and integrating the obtained m multiplied by n test data to finish the characterization of the material form.
In order to further explain the operation of the array sensor in detail, three operation modes of the 4 × 4 array sensor are specifically described as an example. Firstly, detecting the surface morphology of a substance; secondly, detecting the distribution uniformity inside the substance; and detecting the micro-nano structure on the surface of the substance. The resonant array sensor has a certain radiation height, when the longitudinal radiation of the sensor can penetrate through a sample, the surface morphology of the sensor can be detected, and the array sensor is in a first working mode; when the sample can completely cover the radiation of the sensor, the sensor can be utilized to detect the internal distribution uniformity and the surface micro-nano structure, and the array sensor is in a second working mode and a third working mode; when a sample is placed above the sensor, the resonant frequency will move to the left and the resonant amplitude will decrease because the dielectric constant and dielectric loss of the sample to be measured are greater than those of air. In a first working mode, a sample needs to be placed close to the array sensor, different surface forms correspond to different microwave response parameters, resonant mode deflection corresponding to a concave surface form is small, and resonant mode deflection corresponding to a convex surface form is small. In the second working mode, the sample also needs to be placed close to the array sensor, if the internal distribution of the substance is uniform, the dielectric property of each detection point (the position of the resonant unit) is the same, and finally the response parameter of each unit is the same, and if the microwave parameter of the array unit in a certain area changes, the internal distribution of the sample in the area is not uniform. In the third working mode, a certain distance is needed between the sample and the array sensor, the measured surface of the sample needs to be close to the array sensor, the detection mechanism is the same as that of the first working mode, the deviation of the resonance mode corresponding to the convex state is large, and the deviation of the resonance mode corresponding to the concave state is small.
The first mode of operation: the detection of the surface morphology of the thin film type substance is shown in fig. 2. Firstly, placing a hemispherical sample with uniform internal distribution close to an array sensor, and accurately aligning the center of a hemisphere with the center of the sensor;
because the dielectric constant and dielectric loss of the sample are larger than those of air, when the sample is placed above the array sensor, the equivalent circuit model of the system formed by the sensor and the sample together changes, namely the equivalent capacitance of the system is increased, and the equivalent circuit model is formed by a formula of resonance frequency
It can be seen that the increase of the equivalent capacitance causes the resonant frequency to decrease, the resonant mode moves to a low frequency, and the thicker the sample at the detection point, the lower the resonant frequency. In addition, the sample has certain dielectric loss, and the higher the sample is, the higher the dielectric loss isThe larger the electrical loss, the smaller the resonant mode amplitude appears in the detection data. The thickness of the sample can therefore be modeled linearly in terms of the frequency and amplitude shift of the resonant modes. After the sample is placed, the port control circuit starts to work, firstly, the radio frequency switch of the first transmission line is controlled to be turned on, so that two ends of the array 1 are connected with the VNA, then, the diode control circuit starts to work, reverse voltages are loaded at two ends of the variable capacitance diodes from the unit 11 to the unit 24 respectively to enable the variable capacitance diodes to be conducted in succession, and namely, the hemispherical sample information corresponding to the unit 11 to the unit 24 is scanned in sequence. Then the above steps are repeated to connect the array 2 into the system, and finally the scanning of the whole 4 x 4 array is completed. For a uniformly distributed substance, only the thickness of the sample causes a difference in the detection data, and therefore the resonance cells corresponding to the same thickness of the sample are grouped into one group (refer to fig. 3), and the cell 22, the cell 23, the cell 32, and the cell 33 are grouped into the first group; cell 12, cell 13, cell 21, cell 31, cell 42, cell 43, cell 34, and cell 24 are in a second group; cell 11, cell 14, cell 41 and cell 44 are a third group. The detection data for each cell in the group is the same and referring to fig. 3, the sample is thickest at the first group, and therefore the frequency and amplitude shift of the resonant mode is greatest, the second group is next to, and the third group is thinnest, and the resonant mode shift is least. And finally, integrating all unit data and converting the unit data into thickness information of the sample to obtain a three-dimensional imaging graph of the surface of the sample to be detected, wherein the denser the unit distribution is, the more accurate the three-dimensional imaging of the sample is.
The second working mode is as follows: and detecting the distribution uniformity inside the substance. Firstly, a sample is placed close to the array sensor, the thickness of the sample is higher than the radiation height of the sensor, and the center of the sample is accurately aligned with the center of the sensor, as shown in FIG. 4; the detection principle and the scanning mode of the array sensor are the same as those of the first working mode, and the dielectric property of the sample can be linearly modeled according to the frequency and amplitude deviation of the resonant mode. The microwave parameters are not influenced by the height of the sample and only relate to the distribution uniformity inside the sample. The detection data obtained from the array units corresponding to the uniform position of the medium should be the same, i.e. the resonant mode shift degree is the same, as the second set of test data in fig. 3; if the dielectric constant of the individual detection points is higher than the normal value, the shift degree of the resonant mode of the abnormal detection points is higher, such as the first set of test data of FIG. 3; if the dielectric constant of the individual probing points is lower than the normal value, the resonant mode shift of the abnormal probing points is lower, as shown in the third set of test data of FIG. 3. And after scanning of all the array units is finished, the dielectric property of each detection point can be obtained, and an internal distribution imaging graph of the sample can be obtained after data are integrated and analyzed.
The third mode of operation: and (5) detecting the micro-nano structure on the surface of the substance. Firstly, a sample with uniformly distributed hemispheres inside is placed at a certain distance from an array sensor, and the surface of the sample needs to be within the radiation height of the sensor, so that the center of the sample is accurately aligned with the center of the sensor, as shown in fig. 5; the detection principle and the scanning mode of the array sensor are the same as the first working mode, and the surface structure of the sample can be linearly modeled according to the frequency and amplitude deviation of the resonant mode. The closer the sample surface is to the detection point of the array sensor, the greater the degree of the resonant mode frequency and amplitude shift generated by the corresponding unit, such as the first set of detection data in fig. 3; the farther the sample surface is from the array sensor, the smaller the shift in resonant mode frequency and amplitude produced by the corresponding element, as shown in the third set of inspection data in fig. 3. And after scanning all the array units is finished, the distance information between each detection point and the sample can be obtained, and an imaging graph of the micro-nano structure on the surface of the sample can be obtained after data is integrated and analyzed.
Referring to fig. 6, fig. 6 shows a cross-sectional view of a microwave resonant array structure, which includes three metal layers and three SiO layers 2 A layer and a silicon substrate layer. The metal layers are respectively a microwave resonance array layer, a grounding layer and a diode voltage control layer from top to bottom, each metal layer comprises two layers of seed metal and electroplated metal, and the silicon substrate is positioned between the metal layer of the microwave device and the metal layer of the grounding layer and is respectively made of SiO 2 A protective layer spaced therefrom, and a final SiO layer 2 The protective layer is located between the ground metal layer and the control metal layer.
The preparation method of the microwave array sensor provided by the embodiment is manufactured by an integrated passive device process, and the specific processing steps are as follows:
the method comprises the following steps: providing a cleaned and dried substrate; cleaning and drying the silicon substrate to obtain a clean silicon substrate 1;
step two: preparing a first SiO on the upper surface of a substrate 1 2 Layer 2 and in the first SiO 2 Growing a first seed metal layer 3 on the upper surface of the layer;
step three: preparing a microwave resonance array layer 4 on the upper surface of the first sub-metal layer 3, arranging a plurality of transmission lines in the microwave resonance array layer 4 at equal intervals in parallel, arranging a plurality of resonance units at equal intervals on two sides of each transmission line along the vertical direction of the transmission lines, and reserving the position of a varactor between each transmission line and each resonance unit;
step four: preparing a second SiO on the lower surface of the substrate 1 2 Layer 5 on the second SiO 2 Growing a second seed metal layer 6 on the lower surface of the layer;
step five: preparing a ground metal layer 7 on the lower surface of the second seed metal layer 6, and generating a third SiO on the lower surface of the ground metal layer 7 2 A layer 8;
step six: in the third SiO 2 Growing a third sub-metal layer 9 on the lower surface of the layer 8, and preparing a varactor voltage control layer 10 on the lower surface of the third sub-metal layer 9;
step seven: each varactor 11 is placed at a reserved position between the transmission line and each resonant cell, one end of the varactor is connected with the ground metal layer 7 through a through hole 12, and the other end is connected with the varactor voltage control layer 10.
The input and output ends of the microwave resonator are led out through jumper wires and are respectively connected with a radio frequency switch, the radio frequency switch is connected with a multiplexer, and the multiplexer is connected with the VNA through a 50 omega SMA adapter. The varactor is controlled by the underlying circuit and is turned on when a reverse voltage is applied.
Determining the distance between adjacent transmission lines according to the preset harmonic amplitude values and the number of the preset transmission lines, and parallelly arranging the transmission lines according to the determined distance between the adjacent transmission lines; determining the distance between the resonant unit and the adjacent transmission line according to the preset harmonic amplitude value, and determining the distance between the adjacent resonant units according to the preset harmonic amplitude value and the number of the preset resonant units; according to the distance between the determined resonant unit and the adjacent transmission line and the distance between the determined adjacent resonant units, a plurality of resonant units are arranged on two sides of each transmission line along the vertical direction of the transmission lines; and taking the central positions of the transmission line and each resonant unit as reserved varactor diode positions. And presetting a harmonic amplitude value not more than 3dB, namely presetting a harmonic amplitude value not more than 3dB of each resonance unit in the prepared microwave resonance array layer.
Wherein the first SiO is 2 Layer 2, second SiO 2 Layer 5 and third SiO 2 The layers 8 are all prepared by a chemical vapor deposition process; the first seed metal layer 3, the second seed metal layer 6, the third seed metal layer 9 and the varactor voltage 10 control layer are all prepared by adopting an evaporation process; the microwave resonance array layer 4 and the grounding metal layer 7 are prepared by adopting an electroplating process.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The microwave array sensor and the manufacturing method thereof provided by the invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, it is possible to make various improvements and modifications to the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (10)
1. A microwave array sensor, comprising:
microwave resonance array: the microwave scattering parameter measuring device comprises mxn resonance units and m/2 transmission lines which are arranged in parallel, wherein the upper side and the lower side of each transmission line in the vertical direction of the transmission lines are respectively connected with the n resonance units, each resonance unit is used as a measuring point of an object to be measured, and the microwave scattering parameter of the object to be measured at each measuring point is obtained through a generated resonance frequency signal so as to realize the representation of physical information of the object to be measured;
varactor array: the microwave resonant array is used for fixing the resonant frequency of the microwave resonant array and comprises mxn variable capacitance diodes, each variable capacitance diode is arranged between one resonant unit and a transmission line connected with the resonant unit, two ends of each variable capacitance diode are connected with control circuits, the control circuits are used for adjusting bias voltages at two ends of each variable capacitance diode so as to adjust the capacitance value of each variable capacitance diode, and the resonant frequency of the resonant unit connected with the variable capacitance diodes is adjusted by adjusting the capacitance value;
a port switch array: the microwave resonance array is used for controlling the transmission of resonance frequency signals generated by the microwave resonance array, the left port and the right port of each transmission line are respectively connected with one radio frequency switch, and the two radio frequency switches connected with the transmission lines are simultaneously turned on or off to control the corresponding transmission lines to carry out signal transmission.
2. The microwave array sensor according to claim 1, wherein the controlling of the corresponding transmission line for signal transmission by turning on or off the two rf switches connected by the transmission line comprises:
and sequentially controlling two radio frequency switches connected on the ith (i is 1,2, …, m/2) transmission line to be simultaneously turned on and off until the transmission of the resonance frequency signals generated by the resonance units on all the transmission lines is completed.
3. The microwave array sensor of claim 1, wherein the rf switch is connected to a vector network analyzer for receiving resonant frequency signals of the resonant units transmitted by the transmission line.
4. The microwave array sensor of claim 1, wherein the rf switch is connected to a multiplexing controller, and the multiplexing controller is configured to control the rf switch to be turned on or off;
the radio frequency switches connected with the left ports of all the transmission lines are connected with the first multiplexing controller together, and the radio frequency switches connected with the right ports of all the transmission lines are connected with the second multiplexing controller together.
5. The microwave array sensor of claim 1, wherein the resonant cells are open resonant rings, each resonant cell being of equal physical size.
6. A method for fabricating a microwave array sensor according to any one of claims 1 to 5, wherein: the method comprises the following steps:
providing a cleaned and dried substrate;
on the upper surface of the substratePreparation of first SiO 2 Layer on the first SiO 2 Growing a first seed metal layer on the upper surface of the layer;
preparing a microwave resonant array layer on the upper surface of the first seed metal layer, wherein a plurality of transmission lines are arranged in the microwave resonant array layer at equal intervals in parallel, a plurality of resonant units are arranged on two sides of each transmission line at equal intervals in the vertical direction of the transmission lines, and a position of a variable capacitance diode is reserved between each transmission line and each resonant unit;
preparing a second SiO on the lower surface of the substrate 2 Layer on the second SiO 2 Growing a second seed metal layer on the lower surface of the layer;
preparing a ground metal layer on the lower surface of the second seed metal layer, and generating a third SiO on the lower surface of the ground metal layer 2 A layer;
in the third SiO 2 Growing a third sub-metal layer on the lower surface of the layer, and preparing a voltage control layer of the varactor on the lower surface of the third sub-metal layer;
and each variable capacitance diode is arranged at a reserved position between the transmission line and each resonant unit, one end of each variable capacitance diode is connected with the grounding metal layer, and the other end of each variable capacitance diode is connected with the variable capacitance diode voltage control layer.
7. The method of claim 6, wherein the reserving a varactor diode between the transmission line and each resonant cell comprises:
determining the distance between adjacent transmission lines according to the preset harmonic amplitude value and the number of the preset transmission lines, and parallelly arranging the transmission lines according to the distance between the adjacent transmission lines;
determining the distance between the resonant unit and the connected transmission line according to the preset harmonic amplitude value, and determining the distance between adjacent resonant units according to the preset harmonic amplitude value and the number of the preset resonant units;
according to the distance between the resonant unit and the connected transmission line and the distance between the resonant units and the adjacent resonant units, arranging a plurality of resonant units on two sides of each transmission line along the vertical direction of the transmission line;
and taking the central positions of the transmission line and each resonant unit as reserved varactor diode positions.
8. The method of claim 7, wherein the predetermined harmonic amplitude is not greater than 3 dB.
9. The method of claim 6, wherein the first SiO is 2 Layer, second SiO 2 Layer and third SiO 2 The layers are all prepared by adopting a chemical vapor deposition process;
the first seed metal layer, the second seed metal layer, the third seed metal layer and the voltage control layer of the variable capacitance diode are all prepared by adopting an evaporation process;
the microwave resonance array layer and the grounding metal layer are prepared by adopting an electroplating process.
10. The method for manufacturing the microwave array sensor according to claim 6, wherein the left and right ports of the transmission line of the microwave resonant array layer are connected to the radio frequency switch by a jumper wire.
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| CN116470880A (en) * | 2023-06-20 | 2023-07-21 | 麦斯塔微电子(深圳)有限公司 | Anti-symmetrically driven mems resonator |
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| CN116470880A (en) * | 2023-06-20 | 2023-07-21 | 麦斯塔微电子(深圳)有限公司 | Anti-symmetrically driven mems resonator |
| CN116470880B (en) * | 2023-06-20 | 2023-09-19 | 麦斯塔微电子(深圳)有限公司 | Anti-symmetrically driven mems resonator |
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