A glass-encapsulated microbolometer wafer and method of making the same

Abstract

The application discloses a glass-packaged micro thermal conductivity detector wafer and a preparation method thereof, and belongs to the technical field of gas detection. The wafer comprises a plurality of micro thermal conductivity detectors; the plurality of micro thermal conductivity detectors are arranged on a packaging wafer; the packaging wafer is composed of a first glass wafer and a second glass wafer; a plurality of packaging plates are arranged on the first glass wafer; and a plurality of substrates are arranged on the second glass wafer; a plurality of thermal conductivity cells are arranged on the packaging plates; symmetric second half-groove channels are arranged on both sides of the thermal conductivity cells; a plurality of first half-groove channels are arranged on the substrates; the first half-groove channels and the second half-groove channels are matched to form through grooves; the packaging wafer further comprises a plurality of micro circuits; the micro circuit comprises a Wheatstone bridge and electrodes connected to both ends of the Wheatstone bridge; and pads are arranged on the top of the electrodes. The application enlarges the effective sealing area, improves the air tightness, shortens the heat dissipation path of the thermal element, effectively reduces heat loss, and improves the sensitivity of the device.

Description

Technical Field

[0001] This application belongs to the field of gas detection technology, and specifically relates to a glass-encapsulated miniature thermal conductivity detector wafer and its fabrication method. Background Technology

[0002] A thermal conductivity detector is a general-purpose concentration detector that operates based on the physical principle that different gases or vapors have different thermal conductivities. When a mixture of carrier gas and analyte flows through a thermistor heated by a constant current, the change in the thermal conductivity of the mixture causes a change in the temperature and resistance of the thermistor. By placing the thermistor in a Wheatstone bridge, the resistance change can be converted into a measurable voltage signal, thereby enabling qualitative or quantitative analysis of the gas component concentration.

[0003] Traditional thermal conductivity detectors have become one of the most classic and widely used detectors in gas chromatographs due to their advantages such as simple structure, stable performance, response to both inorganic and organic compounds and non-destructive to samples. They are widely used in many fields such as environmental monitoring, petrochemicals, food safety and high-purity gas impurity analysis.

[0004] However, traditional thermal conductivity detectors also have several inherent limitations: (1) Large size and power consumption: The core hot wire cell is usually made of metal blocks with a large heat capacity, requiring high heating power, usually several watts to tens of watts, to maintain a stable operating temperature, resulting in long preheating time and high energy consumption. (2) Limited response speed: The large cell volume is usually microliters, and the thermal mass results in a large time constant, with a relatively slow response, which is not conducive to rapid chromatographic analysis. (3) Low system integration: Traditional structures are difficult to miniaturize, which is not compatible with the trend of modern analytical instruments towards miniaturization, portability, and arraying, limiting their application in on-site rapid detection, lab-on-a-chip, or micro-chromatographic systems.

[0005] In recent years, with the maturation of microelectromechanical systems (MEMS) technology, miniature thermal conductivity detectors have emerged. These detectors utilize microfabrication techniques to integrate and fabricate micrometer-scale gas channels, thermistors, and support structures on substrates such as silicon and glass. The main potential advantages of these miniature devices are: significantly reduced size, down to the cubic millimeter level; extremely low thermal mass; drastically reduced power consumption, down to the milliwatt level; and the promise of faster thermal response and higher sensitivity.

[0006] However, the current MEMS (Micro-Electro-Mechanical System) manufacturing of μTCD (micro thermal conductivity detector) has the following problems: (1) The side lead packaging method is used, which limits the high-density integrated design and manufacturing of μTCD and increases the complexity of wafer-level packaging process; (2) Current cases use both silicon and glass materials and use anodic bonding to realize glass-silicon and glass-silicon-glass packaging structures. The thermal element is made on the silicon substrate. However, silicon has a much faster heat dissipation rate than glass. In order to ensure that the thermal element and the gas to be measured can have sufficient heat exchange, the thermal element made on the silicon substrate needs to be suspended and released. At the same time, in order to reduce the heat loss on the silicon substrate, a protective layer needs to be made on the silicon substrate.

[0007] One prior art discloses a dual-sensitivity µTCD structure with two thermistors in each airflow channel, arranged in parallel within the same thermal conductivity cell. This structure improves the sensitivity of the miniature thermal conductivity detector. However, this device still uses traditional single-device packaging and connects to external circuits via side leads. The device structure employs glass-silicon anodic bonding. Another prior art discloses a wafer-level packaged miniature thermal conductivity detector and its fabrication method. This method utilizes MEMS technology to design and fabricate a μTCD wafer-level package on a wafer through glass-silicon bonding. However, this device uses side leads for external circuit connection, limiting its high-density integration and increasing the complexity of the wafer-level packaging process. This device also still uses glass-silicon anodic bonding. Summary of the Invention

[0008] To address the aforementioned issues, this application provides a glass-encapsulated miniature thermal conductivity detector wafer and its fabrication method.

[0009] The first objective of this application is to provide a glass-encapsulated miniature thermal conductivity detector wafer, comprising multiple miniature thermal conductivity detectors; Multiple miniature thermal conductivity detectors are deployed on a packaged wafer, which is composed of a first glass wafer and a second glass wafer. The first glass wafer has multiple packaging plates deployed on it, and the second glass wafer has multiple substrates deployed on it. The encapsulation board is provided with a plurality of thermal conductivity pools, and symmetrical second half-groove channels are provided on both sides of the thermal conductivity pools. The substrate is provided with a plurality of first half-groove channels, and the first half-groove channels and the second half-groove channels cooperate with each other to form a through groove. The packaged wafer also includes several microcircuits, each including a Wheatstone bridge and electrodes connected to both ends of the Wheatstone bridge, with pads on the top of the electrodes.

[0010] In a specific embodiment of this application, the Wheatstone bridge is disposed within the thermal conductivity cell, the electrode is disposed within the through hole of the packaging plate, and the pad is disposed on the surface of the packaging plate.

[0011] In a specific embodiment of this application, the first glass wafer is further provided with a first alignment mark and a second alignment mark, and the second glass wafer is further provided with a third alignment mark and a fourth alignment mark; The position of the third alignment mark matches the position of the first alignment mark or the second alignment mark, and the position of the fourth alignment mark matches the position of the second alignment mark or the first alignment mark.

[0012] In a specific embodiment of this application, both the substrate and the encapsulation plate are glass plates.

[0013] In a specific embodiment of this application, the through groove contains several pipes.

[0014] In a specific embodiment of this application, the plane containing the pads is parallel to the plane containing the Wheatstone bridge, and the plane containing the axis of the electrode is perpendicular to the plane containing the Wheatstone bridge.

[0015] In a specific embodiment of this application, the diameter of the through groove is 600-1000 μm.

[0016] In a specific embodiment of this application, the thickness of the Wheatstone bridge is 200-500 nm.

[0017] In a specific embodiment of this application, the diameter of the thermal conductivity cell is 200-300 μm, and the diameter of the electrode is 100-300 μm.

[0018] The second objective of this application is to provide a method for fabricating a glass-encapsulated miniature thermal conductivity detector wafer, comprising: First glass wafer processing: Through holes are processed on the first glass wafer; Sandblasting is performed on the first glass wafer to obtain a thermal conductivity cell; Sandblasting is performed on both sides of the thermal conductivity cell at symmetrical positions to obtain a second half-groove channel; Second glass wafer processing: A Wheatstone bridge is processed on the second glass wafer; Sandblasting is performed on the second glass wafer to obtain the first half-groove channel, thus completing the processing of the first glass wafer; Packaging: The processed packaging board and the processed substrate are packaged together to ensure that the first half-groove channel and the second half-groove channel cooperate with each other; electrode material is filled into the through hole to obtain the electrode; solder pads are deposited on the surface of the packaging board by magnetron sputtering to obtain the wafer.

[0019] In a specific embodiment of this application, the thickness of the encapsulation plate is 400-600μm and the size is 4-8 inches.

[0020] In a specific embodiment of this application, the thickness of the substrate is 400-1000 μm and the size is 4-8 inches.

[0021] In a specific embodiment of this application, the fabrication of a Wheatstone bridge on the substrate includes: A Wheatstone bridge pattern is obtained by homogenizing, photolithography, and development on the surface of a glass wafer. Metal electrodes were deposited on glass wafers using magnetron sputtering, with materials including Cr-Pt, Cr-Ni, Ti-Pt, and Ti-Ni. The Cr-Pt, Cr-Ni, Ti-Pt, and Ti-N layers are all composite layers, meaning that a Cr / Ti layer is first fabricated, followed by a Pt / Ni layer. The Cr and Ti layers serve as adhesion layers to enhance the adhesion between the Pt / Ni layer and the wafer. The thickness of the Cr / Ti adhesion layers is independently 10-40 nm, and the thickness of the Pt / Ni layers is independently 200-500 nm.

[0022] The preparation of metal electrodes by magnetron sputtering is a well-known operation in this technical field, and will not be described in detail here.

[0023] The photoresist is cleaned to achieve metal stripping and obtain a Wheatstone bridge. The solution used to clean the photoresist is an acetone solution.

[0024] In a specific embodiment of this application, the electrode material is one of Au, Ag, and Cu.

[0025] In a specific embodiment of this application, the material of the pad is TiAu.

[0026] The Ti-Au layer is a composite layer, that is, a Ti layer is first made and then an Au layer is made. The Ti layer is used as an adhesion layer to enhance the adhesion between Au and the wafer. The thickness of the adhesion layer Ti layer is 10-40nm and the thickness of the Au layer is 300-600nm.

[0027] In a specific embodiment of this application, the packaging of the first glass wafer and the second glass wafer includes: The first and second glass wafers are aligned before welding, and a preset pressure is applied to obtain an aligned sample. Fix the laser beam and move it to align with the sample, so that the laser beam sweeps across the sample. The preset pressure is 0.3 MPa-0.4 MPa, and the scanning speed is 20-30 mm / s; The laser beam has the following parameters: wavelength 1064 nm, repetition frequency 300 kHz, pulse width 15 ps, pulse energy 11.7 uJ, maximum output power 12.78 W, and spot size 40 ± 2 μm.

[0028] Specifically, the implementation of fixing the laser beam and moving it to align with the sample includes: The microscope objective used to focus the laser beam is vertically mounted on a z-axis displacement stage, which allows it to adjust the position of the laser focus, which is the contact surface between the upper and lower wafers. The aligned sample is placed on a CNC two-axis precision displacement stage, which can scan in the xy plane according to a preset trajectory.

[0029] Compared with the prior art, this application has the following advantages: This application discloses a glass-encapsulated miniature thermal conductivity detector wafer and its fabrication method. The wafer is formed by ultrafast laser welding and encapsulating glass wafers together. Instead of traditional side leads, the method uses "electrodes disposed within through-holes in the encapsulation plate" and "pads disposed on the surface of the encapsulation plate," resulting in a new sensor structure and achieving high-density wafer-level packaging. The advantages of this innovation are: first, it increases the effective encapsulation area, improves hermeticity, and shortens the heat dissipation path of the thermal element, effectively reducing heat loss and improving device sensitivity; second, it reduces the process complexity of wafer-level packaging and increases the chip density that can be integrated on the wafer; and third, it achieves all-glass encapsulation, reducing heat loss and noise interference.

[0030] The product in this application innovatively develops a wafer-level packaging process route based on TGV technology, wafer precision sandblasting technology, laser welding, laser cutting and other technologies, providing a new solution for traditional MEMS sensor structure design and wafer-level manufacturing.

[0031] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1A schematic diagram of the structure of a miniature thermal conductivity detector according to an embodiment of this application is shown; Figure 2 An exploded view of a miniature thermal conductivity detector according to an embodiment of this application is shown; Figure 3 A top view of a miniature thermal conductivity detector according to an embodiment of this application is shown; Figure 4 A side view of a miniature thermal conductivity detector according to an embodiment of this application is shown; Figure 5 One of the plan views of a glass-encapsulated miniature thermal conductivity detector wafer according to an embodiment of this application is shown; Figure 6 One of the plan views of a glass-encapsulated miniature thermal conductivity detector wafer according to an embodiment of this application is shown; Figure 7 A schematic diagram of the packaging process according to Embodiment 1 of this application is shown; Figure 8 A physical image of the packaged wafer prepared according to Embodiment 1 of this application is shown; Figure 9 A physical image of a single μTCD prepared according to Example 1 of this application is shown; In the picture: 10. Substrate; 20. Packaging board; 30. Thermal conductivity cell; 31. First thermal conductivity cell; 32. Second thermal conductivity cell; 40. Through slot; 41. First half-slot channel; 42. Second half-slot channel; 50. Microcircuit; 51. Wheatstone bridge; 52. Electrode; 53. Pad; 60. Packaging wafer; 61. First glass wafer; 62. Second glass wafer; 63. First alignment mark; 64. Third alignment mark; 65. Second alignment mark; 66. Fourth alignment mark; 70. Laser beam; 71. Microscope objective; 80. Solder joint. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] like Figure 5 As shown, a wafer-level packaged micro thermal conductivity detector wafer according to certain embodiments of the present invention includes a plurality of micro thermal conductivity detectors (hereinafter referred to as μTCDs). Multiple of the aforementioned miniature thermal conductivity detectors are deployed on the packaged wafer 60 (see details). Figure 6 The packaged wafer 60 is composed of a first glass wafer 61 and a second glass wafer 62. The first glass wafer 61 is provided with a plurality of packaged plates 20, and the second glass wafer 62 is provided with a plurality of substrates 10. like Figure 1 As shown, the encapsulation plate 20 is provided with a plurality of thermal conductivity pools 30, and symmetrical second half-groove channels 42 are provided on both sides of the thermal conductivity pools 30. The substrate 10 is provided with a plurality of first half-groove channels 41. The first half-groove channels 41 and the second half-groove channels 42 cooperate with each other to form a through groove 40 (see details). Figure 2 ); The packaged wafer 60 also includes several microcircuits 50, each microcircuit 50 including a Wheatstone bridge 51 and electrodes 52 connected to both ends of the Wheatstone bridge 51, with pads 53 on the top of each electrode 52.

[0036] In a specific embodiment of this application, the Wheatstone bridge 51 is disposed within the thermal conductivity cell 30, the electrode 52 is disposed within the through hole of the packaging plate 20, and the pad 53 is disposed on the surface of the packaging plate 20.

[0037] In a specific embodiment of this application, the first glass wafer 61 is further provided with a first alignment mark 63 and a second alignment mark 65, and the second glass wafer 62 is further provided with a third alignment mark 64 and a fourth alignment mark 66. The position of the third alignment mark 64 matches the position of the first alignment mark 63 or the second alignment mark 65, and the position of the fourth alignment mark 66 matches the position of the second alignment mark 65 or the first alignment mark 63. In this embodiment of the application, the positional markings between the first alignment mark 63, the second alignment mark 65, the third alignment mark 64, and the fourth alignment mark 66 enable the mutual cooperation between the first half-groove channel 41 and the second half-groove channel 42. For example... Figure 5 As shown, for example, the first alignment mark 63 and the third alignment mark 64 are positioned opposite each other, and the second alignment mark 65 is positioned opposite the fourth alignment mark 66.

[0038] In a specific embodiment of this application, a plurality of pipes are inserted into the through groove 40 to guide the entry and exit of the gas to be tested and / or the carrier gas. For example, there are four pipes, two of which are inlet pipes and two are outlet pipes.

[0039] In a specific embodiment of this application, for example, in one μTCD, the number of microcircuits 50 is four. Every two microcircuits 50 are arranged side-by-side between two symmetrically arranged through-slots 40, facilitating the passage of the gas to be measured and / or the carrier gas through the Wheatstone bridge 51. The four microcircuits 50 are arranged in two rows and two paths, corresponding to four through-slots 40. The number of thermal conductivity cells 30 is also two. See details... Figure 3 ; In an embodiment, the thermal conductivity cell 30 includes a first thermal conductivity cell 31 and a second thermal conductivity cell 32. Hydrogen or helium is introduced into two pipes connected to the first thermal conductivity cell 31 as a carrier gas. Two electrodes on the first thermal conductivity cell 31 serve as reference electrodes. A mixture of the gas to be tested and the carrier gas is introduced into two pipes connected to the second thermal conductivity cell 32. Two electrodes on the second thermal conductivity cell 32 serve as reference electrodes. Because the thermal conductivity coefficients of the gas in the carrier gas channel and the gas mixture channel are different, the Wheatstone bridge 51 changes differently, causing the bridge to become unbalanced. The output voltage difference reflects the physical characteristics of the gas to be tested, such as its concentration and flow rate.

[0040] In a specific embodiment of this application, the plane containing the pad 53 is parallel to the plane containing the Wheatstone bridge 51, and the plane containing the axis of the electrode 52 is perpendicular to the plane containing the Wheatstone bridge 51. See details... Figure 4 .

[0041] In a specific embodiment of this application, the first semi-cylindrical channel 41 and the second semi-cylindrical channel 42 are semi-cylindrical in shape, and the through groove 40 formed by the cooperation of the first semi-cylindrical channel 41 and the second semi-cylindrical channel 42 is circular in shape.

[0042] In a specific embodiment of this application, the diameter of the through groove 40 is 600-1000 μm.

[0043] In a specific embodiment of this application, the thickness of the Wheatstone bridge 51 is 200-500 nm.

[0044] In a specific embodiment of this application, the diameter of the thermal conductivity pool 30 is 200-300 μm.

[0045] In a specific embodiment of this application, the diameter of the electrode 52 is 100-300 μm.

[0046] In a specific embodiment of this application, a plurality of the μTCDs are arranged in an array on the packaging wafer 60, such as... Figure 6 As shown, this facilitates the subsequent cutting of individual μTCDs. For example, the packaged wafer 60 contains 150 μTCDs.

[0047] A method for fabricating a wafer-level packaged micro thermal conductivity detector wafer according to certain embodiments of this application includes: Processing of the first glass wafer 61: Through holes are processed on the first glass wafer 61; sandblasting is performed on the first glass wafer 61 to obtain a thermal conductivity cell 30; sandblasting is performed on both sides of the thermal conductivity cell 30 at symmetrical positions to obtain a second half-groove channel 42, thus completing the processing of the first glass wafer 61. Processing of the second glass wafer 62: A Wheatstone bridge 51 is processed on the second glass wafer 62; Sandblasting is performed on the second glass wafer 62 to obtain the first half-groove channel 41, thus completing the processing of the second glass wafer 62. Packaging: The first glass wafer 61 and the second glass wafer 62 after processing are packaged to ensure that the first half-groove channel 41 and the second half-groove channel 42 cooperate with each other; the electrode 52 material is filled into the through hole to obtain the electrode 52; the pads 53 are plated on the surface of the packaging plate 20 to obtain the packaged wafer 60.

[0048] In some embodiments of this application, the encapsulation plate 20 has a thickness of 400-600 μm and a size of 4-8 inches.

[0049] In some embodiments of this application, the substrate 10 has a thickness of 400-1000 μm and a size of 4-8 inches.

[0050] Example 1 A method for fabricating a glass-encapsulated miniature thermal conductivity detector wafer, comprising: First step: Fabrication process of the first glass wafer 61: Step 1: First, select a 4, 6, or 8-inch, 600 μm thick first glass wafer 61, and use a laser to modify the glass micro-hole area and alignment mark area; among them, the infrared picosecond laser has a laser power of 60 W and a scanning speed of 200 mm / s. Step 2: The modified first glass wafer 61 is placed in an etching solution to etch glass micro-vias and alignment marks (first alignment mark 63 and second alignment mark 65); wherein, the etching solution is a 5% hydrofluoric acid solution, and ultrasonic etching is performed for 1 hour.

[0051] Step 3: Sandblasting is performed using sandblasting equipment to obtain a semi-cylindrical first thermal conductivity pool 31 and a second thermal conductivity pool 32 with a diameter of 200μm; wherein, the sandblasting time is 15 min and the sandblasting pressure is 0.2-0.7 MPa; Step 4: Sandblasting is performed using sandblasting equipment to obtain a semi-cylindrical first semi-groove channel 41 with a diameter of 600μm; wherein, the sandblasting time is 30min and the sandblasting pressure is 0.2-0.7 MPa; Second process: Fabrication of the second glass wafer 62 Step 1: Select a 4, 6, or 8-inch second glass wafer with a thickness of 1000μm and perform cleaning; Step 2: A pattern for the Wheatstone bridge 51 is obtained by homogenization, photolithography, and development on the surface of the second glass wafer 62; wherein the pre-baking temperature is 90–120℃ and the exposure power is 30–80 mJ / cm². 2 Exposure wavelength 365nm (i-line), post-baking temperature 110-130℃, developer solution 2.38% TMAH aqueous solution, development time 30-90s, development temperature 20-25℃; Step 3: Etch alignment marks (third alignment mark 64 and fourth alignment mark 66) on the second glass wafer 62; Deposit metal material on the second glass wafer 62 by magnetron sputtering. The metal material is Cr-Ni, with the thickness of the Cr layer being 30nm and the thickness of the Ni layer being 250nm. Step 4: Clean the photoresist in acetone solution to achieve metal stripping and fabricate Wheatstone bridge 51; Step 5: Sandblasting is performed using sandblasting equipment to obtain a semi-cylindrical first semi-groove channel 41 with a diameter of 600μm; wherein, the sandblasting time is 30 min and the sandblasting pressure is 0.2-0.7 MPa; Third process: Wafer-level packaging process Step 1: Wafer-level packaging is performed using ultrafast femtosecond lasers, specifically including: i. Before welding, the first glass wafer 61 and the second glass wafer 62 are aligned and a preset pressure of 0.3MPa is applied. The alignment is judged by the overlap between the first alignment mark 63, the second alignment mark 65 and the third alignment mark 64, the fourth alignment mark 66. If the marks overlap in pairs, it means that the sample is aligned. ii. The microscope objective 71 for focusing the laser beam is vertically mounted on a z-axis displacement stage, allowing adjustment of the laser focal point position. The laser focal point position is the contact surface between the upper and lower wafers (i.e., forming the solder joint 80, see details). Figure 7 ); iii. The welding adopts a strategy of keeping the laser beam stationary while the sample moves. The aligned sample is fixed on a CNC two-axis precision displacement stage, which can scan in the xy plane according to a preset trajectory. The scanning speed is set to 25mm / s. The laser beam is a picosecond laser with parameters of wavelength 1064 nm, repetition frequency 300 kHz, pulse width 15 ps, pulse energy 11.7 uJ, maximum output power 12.78 W, and spot size of 40±2 μm. Step 2: Fill the blind holes with metal using screen printing or electroplating to prepare TGV electrode 52. Common parameters for screen printing are: squeegee pressure 0.1–0.3 MPa, printing speed 50–200 mm / s, curing temperature 120–180℃. Common parameters for electroplating with copper are: current density 1–3 A / dm², electrolyte temperature 50–60℃, pH value 8–10, and filling time 30–120 min. Step 3: Using magnetron sputtering, TiAu is deposited on the glass surface to create metal pads 53, resulting in a completed packaged wafer 60; wherein, the base temperature is room temperature to 200℃, the sputtering power is 100 to 300W, the working pressure is 0.3 to 1Pa, the argon flow rate is 20 to 50 sccm, the sputtering rate is 0.5 to 1.5 nm / s, and the substrate bias is -50 to -100V; Step 4: Obtain individual μTCDs using laser cutting and abrasive wheel cutting methods (see details for individual μTCDs). Figure 9 ).

[0052] A physical image of the packaged wafer 60 obtained in Example 1 is shown below. Figure 8 As shown.

[0053] Comparative Example 1 A method for fabricating a miniature thermal conductivity detector wafer, comprising: Compared with Example 1, the packaging process in the third step is replaced with long pulse welding, while the rest are the same. The parameters of long pulse welding are: single pulse energy 10J, pulse width 10ms, peak power 1000W, spot diameter 0.5mm, and welding point molten pool temperature 2000℃.

[0054] The result showed that the encapsulation failed.

[0055] Comparative Example 2 A method for fabricating a wafer-level packaged micro thermal conductivity detector wafer includes: Compared with Example 1, the encapsulation process in the third step is replaced with thermocompression bonding (diffusion / eutectic bonding), while the rest are the same. The parameters of thermocompression bonding are: pressure: 1-3 MPa, processing temperature: 400℃.

[0056] The results showed that the packaging failed and the wafer broke.

[0057] Comparative Example 3 A method for fabricating a wafer-level packaged micro thermal conductivity detector wafer includes: Compared with Example 1, the encapsulation process in the third step is replaced with anodic bonding, while the rest are the same. The anodic bonding parameters are: voltage: 1200 V, processing temperature: 350℃, and pressure: 0.2-1 MPa.

[0058] The result showed that the encapsulation failed.

[0059] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A glass-encapsulated miniature thermal conductivity detector wafer, characterized in that, Includes multiple miniature thermal conductivity detectors; Multiple miniature thermal conductivity detectors are disposed on the packaging wafer (60), which is composed of a first glass wafer (61) and a second glass wafer (62). Multiple packaging plates (20) are disposed on the first glass wafer (61), and multiple substrates (10) are disposed on the second glass wafer (62). The encapsulation plate (20) is provided with a plurality of thermal conductivity pools (30), and the thermal conductivity pools (30) are provided with symmetrical second half-groove channels (42) on both sides. The substrate (10) is provided with a plurality of first half-groove channels (41), and the first half-groove channels (41) and the second half-groove channels (42) cooperate with each other to form a through groove (40). The packaged wafer (60) also includes several microcircuits (50), each microcircuit (50) including a Wheatstone bridge (51) and electrodes (52) connected to both ends of the Wheatstone bridge (51), with pads (53) on the top of each electrode (52).

2. The glass-encapsulated miniature thermal conductivity detector wafer according to claim 1, characterized in that, The Wheatstone bridge (51) is disposed in the thermal conductivity cell (30), the electrode (52) is disposed in the through hole of the packaging plate (20), and the pad (53) is disposed on the surface of the packaging plate (20).

3. The glass-encapsulated miniature thermal conductivity detector wafer according to claim 1, characterized in that, The first glass wafer (61) is further provided with a first alignment mark (63) and a second alignment mark (65), and the second glass wafer (62) is further provided with a third alignment mark (64) and a fourth alignment mark (66). The position of the third alignment mark (64) matches the position of the first alignment mark (63) or the second alignment mark (65), and the position of the fourth alignment mark (66) matches the position of the second alignment mark (65) or the first alignment mark (63).

4. The glass-encapsulated miniature thermal conductivity detector wafer according to claim 1, characterized in that, Several pipes are inserted into the through groove (40).

5. A glass-encapsulated miniature thermal conductivity detector wafer according to claim 1, characterized in that, The plane containing the pad (53) is parallel to the plane containing the Wheatstone bridge (51), and the plane containing the axis of the electrode (52) is perpendicular to the plane containing the Wheatstone bridge (51).

6. The glass-encapsulated miniature thermal conductivity detector wafer according to claim 1, characterized in that, The diameter of the through groove (40) is 600-1000 μm; The thickness of the Wheatstone bridge (51) is 200-500 nm.

7. A glass-encapsulated miniature thermal conductivity detector wafer according to any one of claims 1-6, characterized in that, The diameter of the thermal conductivity cell (30) is 200-300 μm, and the diameter of the electrode (52) is 100-300 μm.

8. A method for fabricating a glass-encapsulated micro thermal conductivity detector wafer according to any one of claims 1-7, characterized in that, include: Processing of the first glass wafer (61): Through holes are processed on the first glass wafer (61); sandblasting is performed on the first glass wafer (61) to obtain a thermal conductivity cell (30); sandblasting is performed on both sides of the thermal conductivity cell (30) to obtain a second half-groove channel (42), thus completing the processing of sealing the first glass wafer (61); Processing of the second glass wafer (62): A Wheatstone bridge (51) is processed on the second glass wafer (62); Sandblasting is performed on the substrate (10) to obtain the first half-groove channel (41), thus completing the processing of the second glass wafer (62); Packaging: The first glass wafer (61) and the second glass wafer (62) after processing are packaged to ensure that the first half-groove channel (41) and the second half-groove channel (42) cooperate with each other; the electrode (52) material is filled in the through hole to obtain the electrode (52); the pad (53) is plated on the surface of the packaging plate (20) to obtain the packaged wafer (60).

9. The method for fabricating a glass-encapsulated micro thermal conductivity detector wafer according to claim 8, characterized in that, The thickness of the encapsulation board (20) is 400-600μm and the size is 4-8 inches; The substrate (10) has a thickness of 400-1000 μm and a size of 4-8 inches.

10. A method for fabricating a glass-encapsulated micro thermal conductivity detector wafer according to claim 8 or 9, characterized in that, The packaging of the first glass wafer (61) and the second glass wafer (62) includes: The first glass wafer (61) and the second glass wafer (62) are aligned before welding and a preset pressure is applied to obtain an aligned sample; Fix the laser beam (70) and move it to align with the sample so that the laser beam (70) sweeps the sample horizontally; The preset pressure is 0.3 MPa-0.4 MPa, and the scanning speed is 20-30 mm / s; The laser beam (70) has the following parameters: wavelength 1064 nm, repetition frequency 300 kHz, pulse width 15 ps, pulse energy 11.7 uJ, maximum output power 12.78 W, and spot size 40 ± 2 μm.

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