CN117783401B - Single-channel micro-thermal conductivity detector and preparation method thereof - Google Patents
Single-channel micro-thermal conductivity detector and preparation method thereof Download PDFInfo
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- CN117783401B CN117783401B CN202311814338.6A CN202311814338A CN117783401B CN 117783401 B CN117783401 B CN 117783401B CN 202311814338 A CN202311814338 A CN 202311814338A CN 117783401 B CN117783401 B CN 117783401B
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Abstract
本发明提供一种单沟道微热导检测器及其制备方法，在基板中集成了导电连接件，用于替代外接引线，避免了接触电阻的形成，减小了检测器的零点误差和噪声干扰；取消了参考沟道，将参考沟道的热敏电阻直接制备于基板中，避免了参考沟道中气流扰动形成的噪声，同时，减少了一路载气的需求，降低了气相色谱系统的供气负担；本发明的微热导检测器结构简单，能有效提高检测器的检测灵敏度，同时降低气相色谱系统的供气负担，有利于便携式应用，可进一步促进气相色谱系统的微型化。
The present invention provides a single-channel micro-thermal conductivity detector and a preparation method thereof. A conductive connector is integrated in a substrate to replace an external lead, thereby avoiding the formation of contact resistance and reducing the zero point error and noise interference of the detector. The reference channel is eliminated, and the thermistor of the reference channel is directly prepared in the substrate, thereby avoiding the noise formed by the airflow disturbance in the reference channel. At the same time, the demand for one carrier gas is reduced, and the gas supply burden of the gas chromatography system is reduced. The micro-thermal conductivity detector of the present invention has a simple structure, can effectively improve the detection sensitivity of the detector, and at the same time reduce the gas supply burden of the gas chromatography system, which is conducive to portable applications and can further promote the miniaturization of the gas chromatography system.
Description
Technical Field
The invention belongs to the field of micro-electromechanical systems, and relates to a single-channel micro-thermal conductivity detector and a preparation method thereof.
Background
The thermal conductivity detector is a concentration type non-destructive sensor, realizes detection based on the difference of thermal conductivities of different gases, has small volume, low power consumption and light weight, and can meet the miniaturization requirement of a gas chromatography system.
The micro thermal conductivity detector is formed by four thermistors into a Wheatstone bridge, wherein two thermistors are arranged in the reference channel, and the other two thermistors are arranged in the test channel. When the carrier gas in the test channel carries the component gas to be detected, the thermal conductivity changes to cause the resistance value of the thermistor to change, so that the unbalance of the bridge can output an electric signal, and a chromatogram of the gas to be detected is obtained.
The existing micro heat conduction detector generally adopts an external lead wire mode to form a Wheatstone bridge, which inevitably leads to contact resistance, on one hand, the contact resistance is inconsistent to cause the Wheatstone bridge to be unbalanced so as to generate zero point error, on the other hand, the contact resistance also leads to interference signals, the double-channel gas circuit structure with a test channel and a reference channel is easy to generate noise due to unstable gas flow in the reference channel, the signal-to-noise ratio of the detector is reduced, and the double-channel gas circuit structure needs to provide two paths of carrier gas, so that the gas supply burden of a gas chromatography system is increased, and the application scenes such as on-site analysis are not facilitated.
Therefore, it is necessary to provide a single-channel micro thermal conductivity detector and a method for manufacturing the same.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a single-channel micro thermal conductivity detector and a method for manufacturing the same, which are used for solving the problems of the prior art that the micro thermal conductivity detector has a reduced signal-to-noise ratio and a large carrier gas consumption due to its structure.
To achieve the above and other related objects, the present invention provides a single channel micro thermal conductivity detector comprising:
a substrate in which a microchannel is provided;
The thermistor comprises a first thermistor and a fourth thermistor which are arranged on the substrate, and a second thermistor and a third thermistor which are suspended in the microchannel through a supporting structure;
the conductive connecting piece is arranged on the substrate and is connected with the thermistor to form a Wheatstone bridge structure;
And the cover plate is bonded with the substrate, and covers the micro-channel through the cover plate to form a closed micro-channel.
Optionally, the support structure is net-shaped and comprises a first medium layer positioned on the lower surface of the thermistor and a second medium layer positioned on the upper surface of the thermistor.
Optionally, the bonding pads in the conductive connecting piece are exposed out of the cover plate, and the conductive connecting piece and the thermistor are made of the same material.
Optionally, the cover plate is disposed on two opposite sides of the substrate, or the cover plate is disposed on one side of the substrate, and a cover plate accommodating groove disposed corresponding to the microchannel is disposed on one side of the cover plate adjacent to the substrate.
Optionally, the substrate comprises a silicon substrate, a silicon-on-insulator substrate, a ceramic substrate or a glass substrate, and the cover plate comprises a silicon cover plate, a silicon-on-insulator cover plate, a ceramic cover plate or a glass cover plate.
The invention also provides a preparation method of the single-channel micro thermal conductivity detector, which comprises the following steps:
Providing a substrate;
Forming a thermistor, a conductive connecting piece and a supporting structure on the substrate, wherein the thermistor comprises a first thermistor, a second thermistor, a third thermistor and a fourth thermistor, and the conductive connecting piece is connected with the thermistor to form a Wheatstone bridge structure;
providing an upper cover plate and bonding the upper cover plate to the upper surface of the substrate;
Patterning the substrate from a lower surface of the substrate to form a microchannel, and suspending the second thermistor and the third thermistor in the microchannel through the support structure;
and providing a lower cover plate, bonding the lower cover plate on the lower surface of the substrate, and covering the micro-channel by combining the upper cover plate and the lower cover plate to form a closed micro-channel.
The invention also provides a preparation method of the single-channel micro thermal conductivity detector, which comprises the following steps:
Providing a substrate;
Forming a thermistor, a conductive connecting piece and a supporting structure on the substrate, wherein the thermistor comprises a first thermistor, a second thermistor, a third thermistor and a fourth thermistor, and the conductive connecting piece is connected with the thermistor to form a Wheatstone bridge structure;
patterning the substrate to form a microchannel with the bottom in the substrate, and suspending the second thermistor and the third thermistor in the microchannel through the supporting structure;
An upper cover plate is provided and bonded to the upper surface of the substrate, and the micro-channels are covered by the upper cover plate to form closed micro-channels.
Optionally, the substrate has a substrate receiving slot therein and/or the upper cover plate has a cover plate receiving slot therein during bonding.
Optionally, the support structure is formed as a mesh structure.
Optionally, the thermistor is prepared simultaneously with the preparation of the conductive connection member, and the bonding pads in the conductive connection member are exposed from the upper cover plate.
As described above, the single-channel micro thermal conductivity detector and the preparation method thereof integrate the conductive connecting piece in the substrate to replace the external lead, thereby avoiding the formation of contact resistance, reducing zero point error and noise interference of the detector, canceling the reference channel, directly preparing the thermistor of the reference channel in the substrate, avoiding the noise formed by air flow disturbance in the reference channel, reducing the requirement of one path of carrier gas, and reducing the air supply burden of a gas chromatography system.
The micro heat conduction detector has simple structure, can effectively improve the detection sensitivity of the detector, reduces the gas supply burden of a gas chromatography system, is beneficial to portable application, and can further promote the miniaturization of the gas chromatography system.
Drawings
Fig. 1 is a schematic diagram showing a three-dimensional structure of a single-channel micro-heat conduction detector based on a silicon substrate according to a first embodiment and a second embodiment of the present invention.
FIG. 2 is a schematic diagram of the thermistor and support structure of FIG. 1.
Fig. 3 to 4 are schematic layout diagrams of the wheatstone bridge structure in fig. 1.
Fig. 5 is a process flow diagram of a single channel micro thermal conductivity detector according to a first embodiment of the present invention.
Fig. 6 to 10 are schematic structural diagrams showing steps of preparing a single-channel micro thermal conductivity detector based on a silicon substrate according to a first embodiment of the present invention.
FIG. 11 is a flow chart of a process for fabricating a single channel micro-thermal conductivity detector according to a second embodiment of the present invention.
Fig. 12a to 13 are schematic structural diagrams showing steps of preparing a single-channel micro thermal conductivity detector based on a silicon substrate according to a second embodiment of the present invention.
Fig. 14 to 18 are schematic structural diagrams showing steps of preparing a single-channel micro thermal conductivity detector based on a silicon-on-insulator substrate according to a third embodiment of the present invention.
Fig. 19a to 20 are schematic structural diagrams showing steps of preparing a single-channel micro thermal conductivity detector based on a silicon-on-insulator substrate according to a fourth embodiment of the present invention.
Description of the reference numerals
100. Silicon substrate
110. Silicon oxide layer
120. Substrate accommodating groove
210. Glass upper cover plate
211. Cover plate accommodating groove
220. Glass lower cover plate
300. Closed microchannel
301. Micro-channel
400. Thermistor with high temperature resistance
401. First thermistor
402. Second thermistor
403. Third thermistor
404. Fourth thermistor
500. Conductive connecting piece
501. Lead wire
502. Bonding pad
601. A first dielectric layer
602. A second dielectric layer
111. Silicon-on-insulator substrate
101. Underlying silicon
102. Oxygen-buried layer
103. Top silicon
700. Protective layer
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
As described in detail in the embodiments of the present invention, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of explanation, and the schematic drawings 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 actual fabrication.
For ease of description, spatially relative terms such as "under", "below", "beneath", "above", "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 spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures, including embodiments in which the first and second features are formed in direct contact, as well as embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact, and further, when a layer is referred to as being "between" two layers, it may be the only layer between the two layers, or there may be one or more intervening layers.
It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be changed at will, and the layout of the components may be more complex.
Example 1
Referring to fig. 1-10, the embodiment provides a single-channel micro thermal conductivity detector, which comprises a substrate, a thermistor 400, a conductive connecting piece 500 and a cover plate, wherein a micro channel 301 is arranged in the substrate, the thermistor 400 comprises a first thermistor 401 and a fourth thermistor 404 which are arranged on the substrate, a second thermistor 402 and a third thermistor 403 which are suspended in the micro channel 301 through a supporting structure, the conductive connecting piece 500 is arranged on the substrate and connected with the thermistor 400 to form a wheatstone bridge structure, and the cover plate is bonded with the substrate to cover the micro channel 301 through the cover plate to form a closed micro channel 300.
Specifically, referring to fig. 1 to 4, in this embodiment, the conductive connection member 500 is located on the substrate and includes a lead 501 and a bonding pad 502, the lead 501 is connected to the thermistor 400 to form the wheatstone bridge structure, and the thermistor 400 is used as a measuring element for thermal conductivity of gas to perform thermal conductivity detection. The first thermistor 401 is represented by R1, the second thermistor 402 is represented by R2, the third thermistor 403 is represented by R3, the fourth thermistor 404 is represented by R4, the second thermistor 402 and the third thermistor 403 are located in the supporting structure in the microchannel 301, and are suspended in the microchannel 301 by the supporting structure, the resistance values of the second thermistor 402 and the third thermistor 403 change with the change of the gas flowing through the microchannel 301, and the other two thermistors R1 and R4, namely, the first thermistor 401 and the fourth thermistor 404 are located on the surface of the substrate. The pads 502 connected to the wheatstone bridge configuration are denoted as Pad1, pad2, pad3, pad4, where Pad1, pad4 are the power terminals and Pad2, pad4 are the signal terminals.
In this embodiment, the conductive connecting piece 500 is integrated in the substrate, so that it can replace an external lead to perform electrical connection, thereby avoiding the formation of contact resistance and reducing noise interference of the detector, and the micro-thermal conductivity detector only has a single channel, i.e. the reference channel is eliminated, and the thermistors of the reference channel, i.e. the first thermistor 401 and the fourth thermistor 404, are directly arranged in the substrate, thereby avoiding noise caused by air flow disturbance in the reference channel, reducing the requirement of one path of carrier gas, and reducing the air supply burden of the gas chromatography system.
By way of example, the substrate may comprise a silicon substrate 100, a silicon-on-insulator substrate, a ceramic substrate, or a glass substrate, and the cover plate may comprise a silicon cover plate, a silicon-on-insulator cover plate, a ceramic cover plate, or a glass cover plate.
Specifically, referring to fig. 1 to 10, in this embodiment, the substrate is the silicon substrate 100, the cover plate is a glass cover plate, and the cover plates are disposed on opposite sides of the substrate, that is, the cover plates include a glass upper cover plate 210 and a glass lower cover plate 220, but the choice of the material of the single-channel micro-thermal conductivity detector is not limited thereto, and if necessary, the silicon substrate 100 may be replaced by a silicon-on-insulator substrate, a ceramic substrate, or a glass substrate, and the glass upper cover plate 210 may be replaced by a silicon upper cover plate, a silicon-on-insulator upper cover plate, or a ceramic upper cover plate, and the glass lower cover plate 220 may be replaced by a silicon lower cover plate, a silicon-on-insulator lower cover plate, or a ceramic lower cover plate, and the like.
As an example, a cover accommodating groove 211 is disposed on a side of the cover adjacent to the substrate and corresponds to the support structure and the thermistor 400.
Specifically, referring to fig. 10, the glass upper cover plate 210 is provided with the cover plate accommodating groove 211 corresponding to the supporting structure on one side adjacent to the silicon substrate 100 as required to provide sufficient space for the supporting structure, but not limited thereto, and the cover plate accommodating groove 211 may not be provided in the glass upper cover plate 210 when the silicon substrate 100 may provide sufficient space for the supporting structure.
As an example, the support structure is a mesh structure.
Specifically, referring to fig. 2 and 3, the support structure is suspended in the microchannel 301, and preferably the support structure is suspended at the center of the microchannel 301 and is disposed in parallel along the air flow direction. When the supporting structure adopts a mesh structure, the contact area between the second thermistor 402 and the third thermistor 403 on the supporting structure can be increased, and the sensitivity can be increased. Of course, other configurations of the support structure may be employed as desired, without undue limitation.
As an example, the support structure includes a first dielectric layer 601 and a second dielectric layer 602 stacked from bottom to top.
In this embodiment, the support structure is formed by the first dielectric layer 601 and the second dielectric layer 602. Wherein the first dielectric layer 601 is used as a supporting layer, and the second dielectric layer 602 is used as a protective layer. The first dielectric layer 601 may include one or a combination of a silicon oxide layer and a silicon nitride layer, and the second dielectric layer 602 may include one or a combination of a silicon oxide layer and a silicon nitride layer, which may be specifically selected according to needs.
As an example, the conductive connector 500 and the thermistor 400 have the same material, and may be made of different materials as required.
In this embodiment, the conductive connection member 500 is formed on the upper surface of the silicon substrate 100 and is insulated from the silicon substrate 100 by the first dielectric layer 601. The material used for the thermistor 400 may include one of a Pt/Ti stack, a Ni/Cr stack, a W/Ti stack, and a W/Re stack, and may be specifically selected according to the need. The conductive connection 500 may be made of one of a Pt/Ti stack, a Ni/Cr stack, a W/Ti stack, a W/Re stack, an Al/Ti stack and an Au/Ti stack. The conductive connection member 500 and the thermistor 400 are preferably made of the same material, so as to simplify the process, and may be selected according to needs.
As an example, the pads 502 in the conductive connector 500 are preferably exposed from the cover plate for electrical connection, but not limited thereto.
Referring to fig. 5 to 10, the present embodiment further provides a method for manufacturing a single-channel micro thermal conductivity detector, which includes the following steps:
S1, providing a substrate;
S2, forming a thermistor 400, a conductive connecting piece 500 and a supporting structure on the substrate, wherein the thermistor 400 comprises a first thermistor 401, a second thermistor 402, a third thermistor 403 and a fourth thermistor 404, and the conductive connecting piece 500 is connected with the thermistor 400 to form a Wheatstone bridge structure;
S3, providing an upper cover plate, and bonding the upper cover plate on the upper surface of the substrate;
S4, patterning the substrate from the lower surface of the substrate to form a micro-channel 301, and hanging the second thermistor 402 and the third thermistor 403 in the micro-channel 301 through the supporting structure;
And S5, providing a lower cover plate, bonding the lower cover plate on the lower surface of the substrate, and covering the micro-channel 301 by combining the upper cover plate and the lower cover plate to form a closed micro-channel 300.
The method for manufacturing the single-channel micro thermal conductivity detector is not limited thereto, and the method for manufacturing the single-channel micro thermal conductivity detector according to the present embodiment is further described below with reference to fig. 6 to 10.
First, referring to fig. 5 and 6, step S1 is performed to provide a substrate.
Specifically, in the present embodiment, the silicon substrate 100 is used as the substrate, but the substrate is not limited thereto, and the substrate may be replaced by a silicon-on-insulator substrate, a ceramic substrate, a glass substrate, or the like as required, and the choice of the material and the size of the substrate is not limited thereto.
Next, referring to fig. 5 to 9b, step S2 is performed to form a thermistor 400, a conductive connecting member 500 and a supporting structure on the substrate, where the thermistor 400 includes a first thermistor 401, a second thermistor 402, a third thermistor 403 and a fourth thermistor 404, and the conductive connecting member 500 is connected to the thermistor 400 to form a wheatstone bridge structure.
In this embodiment, the support structure may include a first dielectric layer 601 and a second dielectric layer 602 stacked from bottom to top, and the thermistor 400 is located between the first dielectric layer 601 and the second dielectric layer 602, and the preparation steps may include:
First, as shown in fig. 6, a silicon oxide layer 110 is formed on the upper surface of the silicon substrate 100.
Next, as shown in fig. 7, after performing photolithography, the exposed silicon oxide layer 110 is removed by using a buffer oxide etching solution (Buffered Oxide Etchant, BOE), photoresist is removed, and the exposed silicon oxide layer 110 is used as a mask, and the exposed silicon substrate 100 is etched by using a KOH etching solution to form a substrate accommodating groove 120, so as to provide an accommodating space for the support structure, the thermistor 400 and the conductive connecting member 500 to be subsequently prepared, so that subsequent bonding is facilitated, but not limited thereto, for example, a cover plate accommodating groove 211 with the support structure may be formed only in a subsequent upper cover plate, or accommodating grooves corresponding to each other may be formed in the silicon substrate 100 and the upper cover plate, which is not limited thereto.
Next, as shown in fig. 7, after removing the mask formed by the silicon oxide layer 110, the first dielectric layer 601, such as a stacked or single silicon oxide layer or silicon nitride layer of a silicon oxide (SiOx) layer and a silicon nitride (SiNx) layer, is formed on the upper surface of the silicon substrate 100.
Next, as shown in fig. 8, the thermistor 400 is formed on the first dielectric layer 601, where a sputtering method may be used to form the thermistor 400, for example, one of a Pt/Ti stack, a Ni/Cr stack, a W/Ti stack, and a W/Re stack may be used as the thermistor 400, and after performing photolithography, an Ion Beam Etching (IBE) process is used to pattern the thermistor 400 to form the desired thermistor 400, i.e., the first thermistor 401, the second thermistor 402, the third thermistor 403, and the fourth thermistor 404.
In this embodiment, the conductive connection member 500 is prepared simultaneously with the preparation of the thermistor 400, so as to reduce the number of process steps, i.e. the conductive connection member 500 and the thermistor 400 are made of the same material, including one of Pt/Ti stack, ni/Cr stack, W/Ti stack and W/Re stack. The conductive connecting piece 500 includes a lead 501 to connect the thermistor 400 to form a wheatstone bridge structure, and the conductive connecting piece 500 is integrated in the substrate, so that the conductive connecting piece can replace an external lead to perform electrical connection, thereby avoiding the formation of contact resistance and reducing noise interference of a detector. Referring to fig. 10, it is preferable that the pads 502 of the conductive connector 500 are exposed from the upper cover plate for electrical connection.
Next, as shown in fig. 8, the second dielectric layer 602, such as a stacked or single silicon oxide layer or silicon nitride layer of a silicon oxide (SiOx) layer and a silicon nitride (SiNx) layer, is prepared on the surface of the thermistor 400, for protecting the thermistor 400.
Then, as shown in fig. 9a and 9b, photolithography is performed, and a reactive ion etching process (Reactive Ion Etching, RIE) may be used to etch the second dielectric layer 602 and the first dielectric layer 601, so as to remove the dielectric layers in the bonding region and the pad 502 region, facilitate a subsequent bonding process, expose the pad 502, facilitate a subsequent package welding, and etch the dielectric layers inside the support structure, so as to form the support structure with a mesh structure, so as to increase a contact area between the support structure and a sample, and increase sensitivity.
Next, referring to fig. 5 and 10, step S3 is performed to provide an upper cover plate, and the upper cover plate is bonded to the upper surface of the substrate.
In this embodiment, the upper cover plate is a glass upper cover plate 210, but not limited thereto, for example, the upper cover plate may be a silicon-on-insulator upper cover plate, a ceramic upper cover plate, or a silicon upper cover plate, and the choice of the material and the size of the upper cover plate is not limited thereto. The glass top cover plate 210 may be bonded to the silicon substrate 100 using an anodic bond.
Next, referring to fig. 5 and 10, step S4 is performed to pattern the substrate from the lower surface of the substrate to form the micro-channel 301, and the second thermistor 402 and the third thermistor 403 are suspended in the micro-channel 301 by the supporting structure.
Specifically, photolithography is performed from the back surface of the silicon substrate 100, and a deep reactive Ion Etching (DEEP REACTIVE Ion Etching, DRIE) process may be used to etch the silicon substrate 100, so as to form the micro-channel 301 to release the support structure, so that the second thermistor 402 and the third thermistor 403 are suspended in the micro-channel 301 by the support structure.
Next, referring to fig. 5 and 10, step S5 is performed, in which a lower cover plate is provided, and the lower cover plate is bonded to the lower surface of the substrate, and the micro-channel 301 is covered by the upper cover plate and the lower cover plate to form a closed micro-channel 300.
In this embodiment, the lower cover plate is a glass lower cover plate 220, but not limited thereto, for example, the lower cover plate may be a silicon-on-insulator lower cover plate, a ceramic lower cover plate, or a silicon lower cover plate, and the choice of the material and the size of the lower cover plate is not limited thereto. Wherein, the glass lower cover plate 220 and the silicon substrate 100 may be bonded by an anode.
Finally, dicing and packaging steps can be performed to complete the preparation of the single-channel micro thermal conductivity detector.
Example two
Referring to fig. 11-13, the present embodiment also provides another single-channel micro thermal conductivity detector based on a silicon substrate and a method for manufacturing the same, which can be used for manufacturing the single-channel micro thermal conductivity detector, but is not limited thereto, and the difference between the present embodiment and the first embodiment is that referring to fig. 13, only a cover plate is provided on one side of the substrate to form a closed micro channel 300, so as to reduce the number of cover plates.
The preparation method of the single-channel micro thermal conductivity detector can comprise the following steps:
S1, providing a substrate;
S2, forming a thermistor 400, a conductive connecting piece 500 and a supporting structure on the substrate, wherein the thermistor 400 comprises a first thermistor 401, a second thermistor 402, a third thermistor 403 and a fourth thermistor 404, and the conductive connecting piece 500 is connected with the thermistor 400 to form a Wheatstone bridge structure;
S3, patterning the substrate to form a micro-channel 301 with the bottom part positioned in the substrate, and hanging the second thermistor 402 and the third thermistor 403 in the micro-channel 301 through the supporting structure;
And S4, providing an upper cover plate, bonding the upper cover plate on the upper surface of the substrate, and covering the micro-channel 301 by the upper cover plate to form a closed micro-channel 300.
The types of the substrate and the cover plate in the single-channel micro thermal conductivity detector are not limited herein, and referring to the first embodiment, the steps S1 and S2 of the single-channel micro thermal conductivity detector can be referred to the preparation of fig. 6-9 b in the first embodiment, and the description thereof is omitted herein, and only the steps S3 and S4 are described below.
Specifically, as shown in fig. 11, 12a and 12b, step S3 is performed, after the support structure is formed, a dry etching agent such as TMAH or KOH wet etching solution, or a dry etching agent such as SF 6 or XeF 2 is used to remove a portion of the silicon substrate 100 located under the support structure, so as to release the support structure, so as to form the micro-channel 301, or as shown in fig. 12a and 12b, a DRIE process is used to etch the silicon substrate 100 to a certain depth, after photoresist is removed, a dry etching agent such as TMAH or KOH wet etching solution, or a dry etching agent such as SF 6 or XeF 2 is used to remove a portion of the silicon substrate 100 located under the support structure, so as to release the support structure.
Then, as shown in fig. 11 and 13, step S4 is performed to bond the glass upper cover plate 210 and the silicon substrate 100 using, for example, anodic bonding.
Finally, dicing and packaging steps can be performed to complete the preparation of the single-channel micro thermal conductivity detector.
Example III
Referring to fig. 14-18, the present embodiment also provides a single-channel micro thermal conductivity detector based on a silicon-on-insulator substrate and a method for manufacturing the same, which can be used for manufacturing the single-channel micro thermal conductivity detector, but is not limited thereto, and the difference between the present embodiment and the first embodiment is that the substrate adopts the silicon-on-insulator substrate 111 having the bottom silicon 101, the buried oxide layer 102 and the top silicon 103, and the single-channel micro thermal conductivity detector and the method for manufacturing the same can be referred to as the first embodiment, which is not repeated herein, and only the differences will be described below.
Compared with the first embodiment, the embodiment adopts a RIE process to etch the supporting structure, adopts a photoetching DRIE to etch the top silicon 103, adopts a RIE process to etch the exposed buried oxide layer 102, bonds the upper cover plate with the top silicon 103 of the silicon-on-insulator substrate 111, then carries out photoetching and etching from the lower surface of the silicon-on-insulator substrate 111 to form the micro-channel 301 so as to release the supporting structure, bonds the lower cover plate with the silicon-on-insulator substrate 111, and cuts and encapsulates to complete the preparation of the micro-thermal conductivity detector.
Example IV
Referring to fig. 19a to 20, another single-channel micro thermal conductivity detector based on a silicon-on-insulator substrate and a method for manufacturing the same are provided in this embodiment, but the method for manufacturing the single-channel micro thermal conductivity detector is not limited thereto, and the difference between the embodiment and the first embodiment is that the silicon-on-insulator substrate 111 having the bottom silicon 101, the buried oxide layer 102 and the top silicon 103 is mainly used as the substrate, and the first embodiment and the method for manufacturing the same are referred to, and are not described herein again, but only the differences are described below.
Compared with the first embodiment, after etching the second dielectric layer 602 and the first dielectric layer 601 by RIE process, the top silicon layer 103 may be etched by DRIE process after re-etching, and then the exposed buried oxide layer 102 may be etched by RIE process, as shown in fig. 19a, then a protective layer 700, such as one or a stack of SiNx layer and SiOx layer, may be deposited to protect the side walls of the thermistor 400 and the top silicon layer 103, the dielectric layer in the gap between the thermistor 400 may be etched by RIE process after etching, and then the bottom silicon layer 101 may be etched to a certain depth by DRIE process, as shown in fig. 19b, and then a wet etching solution such as TMAH or KOH may be used, or a dry etching agent such as SF 6 or XeF 2 may be used to remove a portion of the bottom silicon layer 101 located under the supporting structure, so as to release the supporting structure, as shown in fig. 20. Etching the protective layer 700 of the bonding region of the top silicon 103, the bonding pad 502 region and the second dielectric layer 602 region by RIE process to facilitate bonding and electrical connection, bonding the upper cover plate and the top silicon 103 by anodic bonding, as shown in fig. 20, and finally dicing and packaging to complete the preparation of the single-channel micro thermal conductivity detector.
In summary, the single-channel micro thermal conductivity detector and the preparation method thereof integrate the conductive connecting piece in the substrate to replace an external lead wire, avoid the formation of contact resistance, reduce zero point error and noise interference of the detector, cancel a reference channel, directly prepare the thermistor of the reference channel in the substrate, avoid noise formed by air flow disturbance in the reference channel, reduce the requirement of one path of carrier gas, and reduce the air supply burden of a gas chromatography system.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (8)
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| TW494233B (en) * | 2000-02-25 | 2002-07-11 | Chung Shan Inst Of Science | Thermal conductivity detector |
| CN109507230A (en) * | 2018-12-14 | 2019-03-22 | 北京工业大学 | A kind of Mechanical Sealed Type micro thermal conductivity detector |
| CN109959747A (en) * | 2017-12-22 | 2019-07-02 | 中国科学院上海微系统与信息技术研究所 | Integrated chip of microchromatographic column and micro thermal conductivity detector and preparation method thereof |
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| ITRM20120311A1 (en) * | 2012-07-04 | 2014-01-05 | Consiglio Nazionale Ricerche | THERMAL CONDUCTIVITY DETECTOR (TCD) FOR FAST GAS-CHROMATOGRAPHY APPLICATIONS (GC). |
| CN108181415B (en) * | 2016-12-08 | 2023-05-12 | 中国科学院上海微系统与信息技术研究所 | Thin film type micro heat conduction detector and preparation method thereof |
| CN111999338B (en) * | 2020-07-22 | 2022-07-22 | 中国科学院上海微系统与信息技术研究所 | Miniature thermal conductivity gas sensor |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TW494233B (en) * | 2000-02-25 | 2002-07-11 | Chung Shan Inst Of Science | Thermal conductivity detector |
| CN109959747A (en) * | 2017-12-22 | 2019-07-02 | 中国科学院上海微系统与信息技术研究所 | Integrated chip of microchromatographic column and micro thermal conductivity detector and preparation method thereof |
| CN109507230A (en) * | 2018-12-14 | 2019-03-22 | 北京工业大学 | A kind of Mechanical Sealed Type micro thermal conductivity detector |
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