High-performance MEMS thermal conductive gas sensor and preparation method thereof

Abstract

The invention provides a high-performance MEMS (Micro Electro Mechanical System) thermal conductive gas sensor and a preparation method thereof, and the high-performance MEMS thermal conductive gas sensor comprises a substrate structure layer, a supporting structure layer, a heating structure layer, a passivation structure layer and an electrode structure layer which are sequentially arranged from bottom to top, the supporting structure layer, the heating structure layer and the passivation structure layer are each provided with a plurality of through holes, the through holes are communicated with the cavity, the cantilever between at least two through holes is in a drum shape, and by means of the design structure, the working concentrated stress of the center of the cantilever is reduced, and the service life of the cantilever is prolonged. The joint of the suspension beam and the heating center is subjected to fillet design, so that the working stress is reduced; and the sensor has the characteristics of miniaturization, low power consumption, compatibility with a CMOS (Complementary Metal-Oxide-Semiconductor Transistor) process and batch production.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal conductivity gas sensing, and in particular is a high-performance MEMS thermal conductivity gas sensor and a preparation method thereof. Background Art

[0002] MEMS thermal conductivity gas sensor is a new device that can monitor the leakage and emission of gases (such as H2, CO2, CH4, refrigerants, etc.) in household, commercial, automotive, and industrial application equipment. The sensor is made using advanced MEMS technology and accurately detects gas concentration by sensing the thermodynamic changes between the measured gases. Compared with non-dispersive infrared (NDIR), catalytic, electrochemical, metal oxide semiconductor and traditional thermal conductivity gas sensors, MEMS thermal conductivity gas sensors have the characteristics of small size, low power consumption, fast response, stable operation, low cost and wide detection range, and can work normally under both aerobic and anaerobic conditions.

[0003] In the prior art, solutions to improve the performance of thermal conductivity sensors have been published from the perspectives of temperature drift, signal noise, and measurement accuracy. However, the device stress problem is still one of the factors that reduce the working stability and reliability of MEMS thermal conductivity gas sensors.

[0004] For example, a miniature thermal conductivity gas sensor disclosed in a Chinese invention patent with an application publication date of 2023.06.02 and application publication number CN116203065A includes a silicon substrate, a support membrane with a central opening is provided on the silicon substrate, a cavity is opened on the silicon substrate corresponding to the central hole of the support membrane, four symmetrical electrode pads are provided at the four corners of the support membrane, four support beams toward the center of the support membrane are connected to a micro-hot plate suspended on the cavity, a serpentine heating wire is provided on the micro-hot plate, four electrode pads are connected to the heating wires respectively via the support beams, four windows are formed between the support beams, the heating wires and the support membrane, and the windows are connected to the cavity of the silicon substrate.

[0005] In the above-mentioned prior art, the stability and reliability problems of the device working process are solved from the perspective of the thermal conductivity gas sensor chip structure, which makes up for the technical defects in this field. However, the center position of the cantilever that plays a load-bearing function in the thermal conductivity device and the connection between the cantilever and the heating center are usually distributed with large concentrated stress. It is necessary to optimize the cantilever structure to reduce the risk of damage to the device structure due to high stress. The stress compensation method is not studied in the above-mentioned invention patent, and the device is still likely to be structurally damaged and have poor stability.

[0006] Therefore, how to effectively solve the problem of MEMS thermal conductivity gas sensors being easily damaged and having poor stability is a technical problem that needs to be solved urgently. Summary of the invention

[0007] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a high-performance MEMS thermal conductivity gas sensor and a preparation method thereof, which solves the problem that the structure of the MEMS thermal conductivity gas sensor is easily damaged and has poor stability.

[0008] The technical solution of this application is: A high-performance MEMS thermal conductivity gas sensor includes a base structure layer, a support structure layer, a heating structure layer, a passivation structure layer, and an electrode structure layer arranged in sequence from bottom to top, wherein the base structure layer includes bottom silicon provided with a cavity, and the support structure layer, the heating structure layer, and the passivation structure layer are provided with a plurality of through holes, the through holes are connected to the cavity, and the cantilever beam between at least two through holes is drum-shaped. The sensor achieves a stronger working stability, and has the characteristics of miniaturization, low power consumption, compatibility with CMOS process, and mass production.

[0009] Furthermore, support columns are arranged below the suspension beam, and the support columns are all in the cavity. The suspension beam combined with the support columns enhances the working stability of the sensor, while greatly reducing the power consumption of the sensor and improving the sensitivity of the sensor.

[0010] Furthermore, a buried oxide layer and a top silicon are sequentially arranged above the bottom silicon from bottom to top.

[0011] Furthermore, the support structure layer and the passivation structure layer both include silicon dioxide material and silicon nitride material.

[0012] Furthermore, the heating structure layer includes a series of resistor bars in a ring shape, and the resistor bars are connected to the supporting structure layer through an adhesive layer, and the adhesive layer serves to enhance the adhesion between the heating layer material and the dielectric layer.

[0013] Furthermore, the width of the resistor strip gradually decreases from the center of the ring to the outer periphery of the ring, achieving extremely high uniformity of temperature distribution. Compared with the serpentine or spiral resistor design in the prior art, the ring-shaped series resistor strip has better performance in terms of heating peak temperature and temperature distribution uniformity, achieving a higher peak temperature at the same power consumption, and a more uniform heating temperature distribution, improving the device response characteristics and sensitivity.

[0014] Furthermore, an adhesive layer is provided on both the upper surface and the lower surface of the resistor bar, and the adhesive layer on the upper surface of the resistor bar, the resistor bar, and the adhesive layer on the lower surface of the resistor bar form a sandwich structure.

[0015] Furthermore, electrode holes are symmetrically arranged on the passivation structure layer, and the electrode holes are arranged at the periphery of the through hole. Electrode holes are opened at specific positions on both sides of the passivation structure layer, so that the electrode structure layer on the electrode hole forms an electrical interconnection with the resistor strip in the heating structure layer to provide power signal input and output.

[0016] A method for preparing a high-performance MEMS thermal conductivity gas sensor comprises the following steps: S1: Etching a cavity with a plurality of supporting pillars at the center of the bottom silicon; S2: forming a buried oxide layer and a top silicon layer on the upper surface of the bottom silicon through bonding and thinning processes; S3: growing a support structure layer on the top silicon by a plasma enhanced chemical vapor deposition process; S4: processing a heating structure layer through photolithography, sputtering, and etching processes; S5: growing a passivation structure layer on the heating structure layer by a plasma enhanced chemical vapor deposition process, and etching electrode holes on the passivation structure layer; S6: The electrode structure layer is processed on the passivation structure layer and forms a good connection with the heating structure layer at the electrode hole position; S7: The front dielectric material is removed to release a plurality of through holes, and the support columns are supported under the cantilever beams between adjacent through holes.

[0017] A method for preparing a high-performance MEMS thermal conductivity gas sensor comprises the following steps: S1: growing a support structure layer on the bottom silicon by plasma enhanced chemical vapor deposition process; S2: Processing a heating structure layer through photolithography, sputtering and etching processes; S3: growing a passivation structure layer on the heating structure layer by a plasma enhanced chemical vapor deposition process, and etching electrode holes on the passivation structure layer; S4: The electrode structure layer is processed on the passivation structure layer and forms a good connection with the heating structure layer at the electrode hole position; S5: forming a plurality of through holes and cavities through photolithography and etching processes.

[0018] The specific beneficial effects of the present invention include: 1. The drum-shaped suspension beam reduces the concentrated stress at the center of the suspension beam. The rounded corners of the supporting column, the drum-shaped suspension beam and the triangular through-hole make the sensor more stable. It is also small, low power, compatible with CMOS technology and can be mass-produced. 2. Use supporting columns to assist the supporting structure to improve the warping of the cantilever beam, and the comprehensive stress compensation design of the structure enables the device to have stronger working stability and life; 3. It has better performance in gas detection range, working stability and response characteristics, and is not limited by aerobic or anaerobic conditions; 4. The design of the resistor strip greatly improves the uniformity of temperature distribution in the thermal conductivity working area, thereby improving the device response characteristics and sensitivity; 5. The present invention can realize the monitoring application of various gases and has great commercial and academic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0020] Figure 1 It is a schematic diagram of Example 1 of the present invention; Figure 2 A top view of the heating layer of Example 1 of the present invention; Figure 3 This is a schematic diagram of the manufacturing process of Example 1 of the present invention; Figure 4 This is a comparison chart of power consumption between cantilever beam sensor and suspended membrane sensor at the same voltage; Figure 5 This is a temperature comparison diagram of the cantilever beam sensor and the suspended membrane sensor under the same voltage; Figure 6 It is a schematic diagram of Example 2 of the present invention; Figure 7 This is a schematic diagram of the manufacturing process of Example 2 of the present invention; Figure 8 It is a schematic diagram of Example 3 of the present invention.

[0021] Description of Figure Numbers: 1. Base structure layer; 2. Support structure layer; 3. Heating the structural layer; 4. Passivating the structural layer; 5. Electrode hole; 6. Electrode structure layer; 7. Through hole; 8. Cantilever beam; 101, bottom silicon; 102, supporting column; 103, cavity; 104, buried oxide layer; 105, top silicon; 301, adhesion layer; 302, resistor strip. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Embodiment 1, a high-performance MEMS thermal conductivity gas sensor, comprising a base structure layer 1, a supporting structure layer 2, a heating structure layer 3, a passivation structure layer 4, and an electrode structure layer 6 arranged in sequence from bottom to top, wherein the base structure layer 1 comprises a bottom silicon 101 provided with a cavity 103, and the supporting structure layer 2, the heating structure layer 3, and the passivation structure layer 4 are each provided with a plurality of through holes 7, wherein the through holes 7 are connected to the cavity 103, and a cantilever beam 8 between at least two through holes 7 is drum-shaped.

[0024] Specifically, the number of the through holes 7 can be four, six, eight, etc. Preferably, Figure 2 As shown, there are eight through holes 7, which are shaped like a triangle, and each corner of the through hole 7 is rounded, which effectively compensates for the stress of the main support beam. Preferably, the bottom side length of the base structure layer 1 is 500-1000 μm.

[0025] On the basis of the above embodiment, support columns 102 are provided below the suspension beam 8 , and the support columns 102 are all in the cavity 103 .

[0026] Specifically, the orthographic projection area of ​​the cavity 103 is greater than the sum of the orthographic projection areas of the through holes 7 .

[0027] Specifically, the cantilever beam 8 formed between the right-angled sides of adjacent through holes 7 is drum-shaped, and the two sides of the cantilever beam protrude toward the inside of the through hole 7. The cantilever beam 8 formed between the oblique sides of adjacent through holes 7 is straight. The cantilever beam 8 is combined with the supporting column 102 to enhance the working stability of the sensor, while greatly reducing the power consumption of the sensor and improving the sensitivity of the sensor. The working principle of the sensor in the present application is that the resistance bar of the heating structure layer 3 generates Joule heat energy under the action of the working voltage, and the Joule heat energy is conducted to the gas to be measured. The resistance value of the resistance bar changes with the concentration change of the gas to be measured, and the concentration of the gas to be measured is detected by analyzing the change of the electrical signal. This part of the energy is dissipated through conduction with the gas, through the solid structure of the device, through thermal radiation, and through convection. The proportion of energy dissipated by gas conduction can be increased by reducing the heat capacity of the device, thereby reducing the energy lost due to the solid structure, thereby improving the sensitivity of the device and reducing power consumption. Figure 4 As shown in , under the same voltage, the cantilever beam sensor has a lower thermal capacity than the suspended film sensor, and therefore exhibits lower power consumption; Figure 5 As shown, under the same voltage, the cantilever beam sensor has a higher heating temperature than the suspended membrane sensor, so the device output changes more and the reaction sensitivity of the detected gas is higher.

[0028] Specifically, the shape of the supporting pillars 102 can be a cylinder, a rectangle or other shapes, and their number can be less than or equal to the number of cantilever beams 8. A cavity 103 is opened inside the base structure layer 1 of the sensor, and pillars 102 are processed in the cavity 103 and under the cantilever beams 8, which alleviates the adverse effects of concentrated stress and warping of the suspended film on the stability of the device and greatly improves the reliability of the device.

[0029] On the basis of the above implementation, a buried oxide layer 104 and a top silicon layer 105 are sequentially arranged on the bottom silicon 101 from bottom to top.

[0030] On the basis of the above-mentioned implementation manner, the support structure layer 2 and the passivation structure layer 4 both include silicon dioxide material and silicon nitride material.

[0031] Specifically, the support structure layer 2 is composed of a combination of low-stress silicon dioxide and silicon nitride materials, with a stack thickness of 1 to 6 μm; in order to protect the entire thermal conductive device, a passivation layer 4 is grown on the heating layer 3, and the passivation structure layer 4 is a single layer of silicon nitride, silicon dioxide or a composite layer of the two.

[0032] On the basis of the above embodiment, the heating structure layer 3 includes a resistor bar 302 in a ring-shaped series connection. The resistor bar 302 is connected to the supporting structure layer 2 through an adhesion layer 301. The adhesion layer 301 serves to enhance the adhesion between the heating layer material and the dielectric layer. The material may be titanium, chromium, tantalum or a combination of multiple materials. The resistor bar 302 may be made of metals such as platinum, tungsten, and titanium nitride. The thickness of the heating structure layer 3 is 200~300nm.

[0033] Based on the above implementation, the width of the resistor bar 302 gradually decreases from the center of the ring to the outer periphery of the ring. Figure 2 As shown, the resistor strip is designed to be annular in series, and the resistor strip adopts a gradient size design, and the width of the annular center resistor strip is greater than the width of the annular peripheral resistor strip, so as to achieve extremely high temperature distribution uniformity. Compared with the serpentine or spiral resistor design in the prior art, the annular series resistor strip has better performance in terms of heating peak temperature and temperature distribution uniformity, achieving a higher peak temperature under the same power consumption, and a more uniform heating temperature distribution, thereby improving the device response characteristics and sensitivity.

[0034] Specifically, the resistor bars 302 are arranged along the circumference of the semicircle and are arranged toward the center of the semicircle in sequence. The width of the resistor bars 302 located near the center of the circle is greater than the width of the resistor bars located at the outer circumference of the circle. The arranged resistor bars 302 are circular.

[0035] Based on the above implementation, the upper and lower surfaces of the resistor bar 302 are both provided with an adhesion layer 301, and the adhesion layer on the upper surface of the resistor bar, the resistor bar, and the adhesion layer on the lower surface of the resistor bar form a sandwich structure. The adhesion layer 301 also adopts the same design as the resistor bar 302, and the adhesion layer 301 and the resistor bar 302 are covered between the support structure layer 2 and the passivation structure layer 4.

[0036] On the basis of the above-mentioned embodiment, the passivation structure layer 4 is symmetrically provided with electrode holes 5, and the electrode holes 5 are provided at the periphery of the through hole 7. Electrode holes 5 are provided at specific positions on both sides of the passivation structure layer 4, so that the electrode structure layer 6 on the electrode hole 5 forms an electrical interconnection with the heating structure layer 3 for power signal input and output, and the material of the electrode structure layer 6 is aluminum, gold, etc.

[0037] A method for preparing a high-performance MEMS thermal conductivity gas sensor comprises the following steps: S1: Etching a cavity 103 with a plurality of supporting pillars 102 at the center of the bottom silicon 101; S2: forming a buried oxide layer 104 and a top silicon layer 105 on the upper surface of the bottom silicon layer 101 through bonding and thinning processes; S3: growing a support structure layer 2 on the top silicon 105 by a plasma enhanced chemical vapor deposition process (PECVD); S4: processing the heating structure layer 3 by photolithography, sputtering and etching processes, which may also be replaced by evaporation and stripping processes; S5: growing a passivation structure layer 4 on the heating structure layer 3 by a plasma enhanced chemical vapor deposition process, and etching electrode holes 5 on the passivation structure layer 4; S6: The electrode structure layer 6 is processed on the passivation structure layer 4 and forms a good connection with the heating structure layer 3 at the position of the electrode hole 5. The geometric parameters of the electrode structure layer 6 can be adjusted according to the device size and actual test needs; S7: removing the front dielectric material to release and form a plurality of through holes 7 , and the support columns 102 are supported under the suspension beams 8 between adjacent through holes 7 .

[0038] Example 2, as a preferred implementation, is different from Example 1 in that a high-performance MEMS thermal conductivity gas sensor includes a base structure layer 1, a support structure layer 2, a heating structure layer 3, a passivation structure layer 4, and an electrode structure layer 6 arranged in sequence from bottom to top, the base structure layer 1 includes a bottom silicon 101 provided with a cavity 103, and the support structure layer 2, the heating structure layer 3, and the passivation structure layer 4 are each provided with a plurality of through holes 7, the through holes 7 are connected to the cavity 103, and the cantilever beam 8 between at least two through holes 7 is drum-shaped.

[0039] Specifically, the number of the through holes 7 can be four, six, eight, etc. Preferably, Figure 2 As shown, there are eight through holes 7, which are shaped like a triangle. Each corner of the through hole 7 is rounded, which effectively compensates for the stress of the main support beam. Preferably, the bottom side length of the base structure layer 1 is 500~1000μm.

[0040] On the basis of the above embodiment, support columns 102 are provided below the suspension beam 8 , and the support columns 102 are all in the cavity 103 .

[0041] Specifically, the orthographic projection area of ​​the cavity 103 is greater than the sum of the orthographic projection areas of the through holes 7 .

[0042] Specifically, the cantilever beam 8 formed between the right-angled sides of adjacent through holes 7 is drum-shaped, and the two sides of the cantilever beam protrude toward the inside of the through hole 7. The cantilever beam 8 formed between the oblique sides of adjacent through holes 7 is straight. This design structure enhances the working stability of the sensor, while greatly reducing the power consumption of the sensor and improving the sensitivity of the sensor. The working principle of the sensor in the present application is that the resistance bar of the heating structure layer 3 generates Joule heat energy under the action of the working voltage, and the Joule heat energy is transmitted to the gas to be measured. The resistance value of the resistance bar changes with the concentration change of the gas to be measured, and the concentration of the gas to be measured is detected by analyzing the change of the electrical signal. This part of the energy is dissipated through conduction with the gas, through the solid structure of the device, through thermal radiation, and through convection. The proportion of energy lost by gas conduction can be increased by reducing the heat capacity of the device, thereby reducing the energy lost by the solid structure, thereby improving the sensitivity of the device and reducing power consumption. Figure 4 As shown in , under the same voltage, the cantilever beam sensor has a lower thermal capacity than the suspended film sensor, and therefore exhibits lower power consumption; Figure 5 As shown, under the same voltage, the cantilever beam sensor has a higher heating temperature than the suspended membrane sensor, so the device output changes more and the reaction sensitivity of the detected gas is higher.

[0043] On the basis of the above implementation, a buried oxide layer 104 and a top silicon layer 105 are sequentially arranged on the bottom silicon 101 from bottom to top.

[0044] On the basis of the above-mentioned implementation manner, the support structure layer 2 and the passivation structure layer 4 both include silicon dioxide material and silicon nitride material.

[0045] Specifically, the support structure layer 2 is composed of a combination of low-stress silicon dioxide and silicon nitride materials, with a stack thickness of 1 to 6 μm; in order to protect the entire thermal conductive device, a passivation layer 4 is grown on the heating layer 3, and the passivation structure layer 4 is a single layer of silicon nitride, silicon dioxide or a composite layer of the two.

[0046] On the basis of the above-mentioned embodiment, the heating structure layer 3 includes a resistor bar 302 in a ring-shaped series connection, and the resistor bar 302 is connected to the supporting structure layer 2 through an adhesive layer 301. The adhesive layer 301 plays a role in enhancing the adhesion between the heating layer material and the dielectric layer, and the material can be titanium, chromium, tantalum or a combination of multiple materials, and the resistor bar 302 can be made of metals such as platinum, tungsten, and titanium nitride.

[0047] On the basis of the above-mentioned implementation, the width of the resistor bar 302 gradually decreases from the center of the ring to the outer periphery of the ring, and the resistor bar 302 is designed to be a ring series connection. The resistor bar 302 adopts a gradient size design, and the width of the resistor bar in the center of the ring is greater than the width of the resistor bar in the outer periphery of the ring, so as to achieve extremely high temperature distribution uniformity. Compared with the serpentine or spiral resistor design in the prior art, the resistor bar in the ring series connection has better performance in terms of heating peak temperature and temperature distribution uniformity, achieving a higher peak temperature under the same power consumption, and the heating temperature distribution is more uniform, which improves the device response characteristics and sensitivity.

[0048] Specifically, the resistor bars 302 are arranged along the circumference of the semicircle and are arranged toward the center of the semicircle in sequence. The width of the resistor bars 302 located near the center of the circle is greater than the width of the resistor bars located at the outer circumference of the circle. The arranged resistor bars 302 are circular.

[0049] Based on the above implementation, the upper and lower surfaces of the resistor bar 302 are both provided with an adhesion layer 301, and the adhesion layer on the upper surface of the resistor bar, the resistor bar, and the adhesion layer on the lower surface of the resistor bar form a sandwich structure. The adhesion layer 301 also adopts the same design as the resistor bar 302, and the adhesion layer 301 and the resistor bar 302 are covered between the support structure layer 2 and the passivation structure layer 4.

[0050] On the basis of the above embodiment, the passivation structure layer 4 is symmetrically provided with electrode holes 5, and the electrode holes 5 are provided at the periphery of the through hole 7. Electrode holes 5 are provided at specific positions on both sides of the passivation structure layer 4, so that the electrode structure layer 6 on the electrode hole 5 is electrically interconnected with the heating structure layer 3 to provide power signal input and output.

[0051] A method for preparing a high-performance MEMS thermal conductivity gas sensor comprises the following steps: S1: growing a support structure layer 2 on the bottom silicon 101 by a plasma enhanced chemical vapor deposition process (PECVD); S2: Processing the heating structure layer 3 by photolithography, sputtering and etching processes, which may also be replaced by evaporation and stripping processes; S3: growing a passivation structure layer 4 on the heating structure layer 3 by a plasma enhanced chemical vapor deposition process (PECVD), and etching electrode holes 5 on the passivation structure layer 4; S4: The electrode structure layer 6 is processed on the passivation structure layer 4 and forms a good connection with the heating structure layer 3 at the position of the electrode hole 5; S5: The front dielectric material is removed to release a plurality of through holes 7, a cavity 103 is etched at the center of the bottom silicon 101, and cantilever beams 8 are formed between adjacent through holes 7. The drum-shaped rounded cantilever beam 8 compensation structure is used to alleviate the influence of concentrated stress on the stability of the device. The process is simpler and is the same as Example 1. It has a design of a heating structure layer 3, and compared with the prior art, higher response characteristics and sensitivity are achieved.

[0052] Example 3, as a preferred embodiment, is different from Example 1 in that Figure 8 As shown, the cantilever beams 8 formed between the right-angled sides and the oblique sides of the adjacent through holes 7 are all drum-shaped, and the two sides of the cantilever beams 8 protrude toward the inside of the through hole 7. The cantilever beams 8 are combined with the supporting columns 102 to enhance the working stability of the sensor, while greatly reducing the power consumption of the sensor and improving the sensitivity of the sensor. The working principle of the sensor in the present application is that the resistance bar of the heating structure layer 3 generates Joule heat energy under the action of the working voltage, and the Joule heat energy is conducted to the gas to be measured. The resistance value of the resistance bar changes with the concentration change of the gas to be measured, and the concentration of the gas to be measured is detected by analyzing the change of the electrical signal. This part of the energy is dissipated through conduction with the gas, through the solid structure of the device, through thermal radiation, and through convection. The energy lost due to gas conduction can be increased by reducing the heat capacity of the device, thereby reducing the energy lost due to the solid structure, thereby improving the sensitivity of the device and reducing power consumption, such as Figure 4 As shown in , under the same voltage, the cantilever beam sensor has a lower thermal capacity than the suspended film sensor, and therefore exhibits lower power consumption; Figure 5 As shown, under the same voltage, the cantilever beam sensor has a higher heating temperature than the suspended membrane sensor, so the device output changes more and the reaction sensitivity of the detected gas is higher.

[0053] The details not described in detail in the present invention are all conventional technical means known to those skilled in the art.

[0054] The above content shows and describes the basic principles, main features and beneficial effects of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high performance MEMS thermal conductivity gas sensor, characterized in that: The invention comprises a base structure layer (1), a support structure layer (2), a heating structure layer (3), a passivation structure layer (4), and an electrode structure layer (6) which are arranged in sequence from bottom to top, wherein the base structure layer (1) comprises a bottom silicon (101) provided with a cavity (103), and the support structure layer (2), the heating structure layer (3), and the passivation structure layer (4) are all provided with a plurality of through holes (7), wherein the through holes (7) are connected to the cavity (103), and the cantilever beam (8) between at least two through holes (7) is in a drum shape.

2. The high performance MEMS thermal conductivity gas sensor according to claim 2, characterized in that: Support columns (102) are arranged below the suspension beam (8), and the support columns (102) are all inside the cavity (103).

3. The high performance MEMS thermal conductivity gas sensor according to claim 1 or 2, characterized in that: A buried oxide layer (104) and a top silicon (105) are sequentially arranged above the bottom silicon (101) from bottom to top.

4. The high performance MEMS thermal conductivity gas sensor according to claim 1 or 2, characterized in that: The supporting structure layer (2) and the passivation structure layer (4) both comprise silicon dioxide material and silicon nitride material.

5. The high performance MEMS thermal conductivity gas sensor according to claim 1 or 2, characterized in that: The heating structure layer (3) comprises a series of resistor bars (302) in a ring shape, and the resistor bars (302) are connected to the supporting structure layer (2) via an adhesive layer (301).

6. The high performance MEMS thermal conductivity gas sensor according to claim 5, characterized in that: The width of the resistor strip (302) gradually decreases from the center of the ring to the outer periphery of the ring.

7. The high performance MEMS thermal conductivity gas sensor according to claim 6, characterized in that: The upper surface and the lower surface of the resistor bar (302) are both provided with an adhesion layer (301).

8. The high performance MEMS thermal conductivity gas sensor according to claim 1, characterized in that: Electrode holes (5) are symmetrically arranged on the passivation structure layer (4), and the electrode holes (5) are arranged on the periphery of the through hole (7).

9. A method for preparing a high-performance MEMS thermal conductivity gas sensor, characterized in that: The high performance MEMS thermal conductivity gas sensor according to any one of claims 1 to 8 is prepared by the following steps: S1: etching a cavity (103) provided with a plurality of supporting pillars (102) at the center of the bottom silicon (101); S2: forming a buried oxide layer (104) and a top silicon layer (105) on the upper surface of the bottom silicon layer (101); S3: growing a support structure layer (2) on the top silicon (105); S4: processing a heating structure layer (3); S5: growing a passivation structure layer (4) on the heating structure layer (3), and providing electrode holes (5) on the passivation structure layer (4); S6: The electrode structure layer (6) is processed on the passivation structure layer (4) and forms a good connection with the heating structure layer (3) at the position of the electrode hole (5); S7: a plurality of through holes (7) are provided, and the supporting columns (102) are supported under the suspension beams (8) between adjacent through holes (7).

10. A method for preparing a high-performance MEMS thermal conductivity gas sensor, characterized in that: The high performance MEMS thermal conductivity gas sensor according to any one of claims 1 to 8 is prepared by the following steps: S1: growing a support structure layer (2) on the bottom silicon (101); S2: Processing a heating structure layer (3); S3: growing a passivation structure layer (4) on the heating structure layer (3), and providing electrode holes (5) on the passivation structure layer (4); S4: the electrode structure layer (6) is processed on the passivation structure layer (4) and forms a good connection with the heating structure layer (3) at the electrode hole (5); S5: providing a plurality of through holes (7) and cavities (103).

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