Micro hot plate and manufacturing method thereof

Abstract

The invention belongs to the technical field of gas sensors of micro-electro-mechanical systems (MEMS), and particularly relates to a micro hot plate and a manufacturing method thereof.The micro hot plate comprises a substrate, an insulating layer is arranged on the top face of the substrate, a plurality of hollow-out structures are formed in the substrate in the circumferential direction at equal intervals, a cantilever beam is formed between every two adjacent hollow-out structures, the hollow-out structures penetrate through the insulating layer, and the cantilever beam penetrates through the insulating layer. A heating electrode, a gear shaping electrode and a temperature measuring electrode are integrated on the top surface of the insulating layer, the heating electrode, the gear shaping electrode and the temperature measuring electrode are all located on the outer sides of the multiple hollow structures, and pins of the heating electrode, the gear shaping electrode and the temperature measuring electrode pass through the multiple cantilever beams and are located on the inner sides of the multiple hollow structures; the corners of the hollow structure are arranged to be round corners. The micro hot plate is high in response speed, low in power consumption, stable in structure, long in service life and high in tolerance.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas sensors of micro-electromechanical systems (MEMS), and in particular relates to a micro-hot plate and a manufacturing method thereof. Background Art

[0002] Micro-electromechanical systems (MEMS) technology, with its miniaturization and easy integration, is considered one of the most influential technologies in the 21st century. With the continuous advancement of silicon-based semiconductor technology, the design of gas sensor structures has also undergone significant changes. The traditional ceramic tube heating structure has been replaced by a new type of micro-hotplate gas sensor.

[0003] Micro-hotplate heating structure has been widely used in the field of gas detection due to its advantages of small size, high sensitivity, low power consumption, fast response speed and low energy consumption. At present, MEMS micro-hotplate structure sensors have gradually become a major structural form in this field, but the existing micro-hotplate design has many disadvantages:

[0004] 1. The micro-hotplate has poor thermal insulation and is prone to thermal crosstalk; 2. The uniformity of the micro-hotplate is too poor and the heating area is not concentrated; 3. The micro-hotplate has low mechanical strength, is easily damaged by thermal stress, and has a short lifespan.

[0005] To this end, a micro hot plate and a manufacturing method thereof are proposed. Summary of the invention

[0006] The object of the present invention is to provide a micro hot plate and a manufacturing method thereof to solve the above problems.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A micro-hotplate comprises: a substrate, an insulating layer is arranged on the top surface of the substrate, a plurality of hollow structures are circumferentially evenly spaced on the substrate, a cantilever beam is formed between two adjacent hollow structures, the hollow structure passes through the insulating layer, a heating electrode, a tooth electrode and a temperature measuring electrode are integrated on the top surface of the insulating layer, the heating electrode, the tooth electrode and the temperature measuring electrode are all located on the outside of the plurality of hollow structures, the pins of the heating electrode, the tooth electrode and the temperature measuring electrode pass through the plurality of cantilever beams and are located on the inside of the plurality of hollow structures respectively, and the corners of the hollow structure are set as rounded corners.

[0009] Preferably, the material of the substrate is one of zirconium oxide, aluminum oxide or silicon dioxide.

[0010] Preferably, the material of the insulating layer is silicon dioxide.

[0011] Preferably, the width of the cantilever beam is one of 14 μm, 28 μm and 42 μm.

[0012] Preferably, the fillet angle is 0.005 μm-0.020 μm.

[0013] Preferably, the heating electrode, the tooth electrode and the temperature measuring electrode are made of platinum electrode material.

[0014] Preferably, the thickness of the heating electrode, the tooth electrode and the temperature measuring electrode is 1 μm-3 μm.

[0015] Preferably, the heating electrode, the tooth electrode and the temperature measuring electrode are located on the same horizontal plane.

[0016] A method for making a micro-hotplate, used for making the micro-hotplate, comprises the following steps: selecting a substrate of set specifications, depositing an insulating layer on the top surface of the substrate, etching and depositing a heating electrode, a tooth electrode and a temperature measuring electrode on the top surface of the insulating layer, using a micro-spraying film-forming method to attach a gas-sensitive film to the tooth electrode for coating a gas-sensitive material, and laser etching a hollow structure according to the shapes of the heating electrode, the tooth electrode, the temperature measuring electrode and the hollow structure to obtain the micro-hotplate.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects:

[0018] In the present invention, the heating electrode, the tooth electrode and the temperature measuring electrode are located in the same plane and are cross-distributed, so that the temperature increases faster, so that the tooth electrode can better receive heat, so that the gas sensor can respond faster and operate with lower power consumption; the heating electrode, the tooth electrode and the temperature measuring electrode do not contact each other, avoiding the influence of circuit crosstalk between the electrodes of the laminated micro-hot plate;

[0019] An insulating layer is provided above the substrate, which separates the substrate from the heating electrode, the tooth electrode and the temperature measuring electrode, and can prevent current leakage and short circuit, ensuring the electrical safety of the micro-hotplate; it has good thermal insulation performance, which helps to maintain the temperature stability of the micro-hotplate during operation, reduce heat loss, and provide mechanical protection to enhance the life of the micro-hotplate;

[0020] By setting up the hollow structure, cantilever beam and rounded corners, the heat conduction area is reduced to reduce thermal stress, and the life of the cantilever beam is enhanced, which effectively avoids the micro-hotplate from cracking due to stress accumulation under the action of thermal stress, improves the reliability and stability of the micro-hotplate structure, and enables the micro-hotplate to be used efficiently in various occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0022] Figure 1 It is a front view of the micro-hotplate of the present invention;

[0023] Figure 2 is a bottom view of the micro-hotplate of the present invention;

[0024] Figure 3 The simulated thermal distribution diagram of the micro-hotplate of the present invention;

[0025] Figure 4 It is a simulated thermal stress diagram of the micro-hotplate of the present invention;

[0026] Figure 5 The micro-hotplate electrode pattern 1 of the present invention;

[0027] Figure 6 The second electrode pattern of the micro-hotplate of the present invention;

[0028] Among them, 1. heating electrode; 2. tooth electrode; 3. cantilever beam; 4. insulating layer; 5. temperature measuring electrode; 6. fillet; 7. substrate; 8. hollow structure. DETAILED DESCRIPTION

[0029] 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.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Reference Figure 1 to Figure 2The present invention discloses a micro-hotplate, comprising: a substrate 7, an insulating layer 4 is arranged on the top surface of the substrate 7, a plurality of hollow structures 8 are circumferentially evenly spaced on the substrate 7, a cantilever beam 3 is formed between two adjacent hollow structures 8, the hollow structure 8 penetrates the insulating layer 4, a heating electrode 1, a tooth electrode 2 and a temperature measuring electrode 5 are integrated on the top surface of the insulating layer 4, the heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 are all located on the outside of the plurality of hollow structures 8, the pins of the heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 pass through the plurality of cantilever beams 3 and are located on the inside of the plurality of hollow structures 8, and the corners of the hollow structure 8 are set as rounded corners 6.

[0032] The number of the hollow structures 8 is preferably four;

[0033] The substrate 7 provides physical support for the micro-hotplate to maintain the shape and dimensional stability of the device; it has good chemical stability to ensure that chemical reactions are not likely to occur during device processing and use.

[0034] The insulating layer 4 is grown on the substrate 7, separating the heating electrode 1, the tooth electrode 2, and the temperature measuring electrode 5 from the substrate 7, which can prevent the circuit from short-circuiting and reduce the heat loss to the substrate. It also has two major characteristics: insulation and heat insulation;

[0035] The cantilever beam 3, as a structural feature, supports the micro-hotplate, reduces the heat conduction area and thus reduces thermal stress;

[0036] Fillet 6 is used to reduce thermal stress;

[0037] The heating electrode 1 is a thin-film resistor made of metal, which uses the Joule heating effect of the current to release heat and provide the required heat for the loaded gas-sensitive material to work;

[0038] The tooth electrode 2 is in direct contact with the metal oxide semiconductor gas-sensitive material to detect the change in resistance of the gas-sensitive material when it is exposed to the gas to be measured or exposed to the air. The presence of the gas to be measured and the concentration of the gas can be detected through the change in resistance.

[0039] The temperature measuring electrode 5 is used to monitor the temperature of the micro-hotplate so as to accurately control the temperature of the micro-hotplate through a feedback control mechanism to maintain a specific operating temperature required by applications such as MEMS sensors.

[0040] The thickness of the micro-hotplate is 50-100 μm, the side length is 0.5 mm-0.8 mm, and the side length of the central heat source area is 0.2 mm-0.3 mm;

[0041] The heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 are all made by magnetron sputtering technology. Specifically, the metal target is loaded into the sputtering chamber, and then evacuated to a high vacuum state to avoid interference from gas molecules. Argon gas is introduced into the sputtering chamber to generate plasma. A negative bias is applied to the substrate 7 to attract the sputtered metal atoms. At the same time, a magnetic field is applied near the target to form magnetron sputtering. The magnetic field causes electrons to form a closed trajectory near the target, increasing the density and sputtering rate of the plasma. Argon ions collide with the metal target, sputtering the metal atoms and depositing them on the substrate 7 to form a metal film to obtain the desired electrode.

[0042] In a feasible solution, the material of the substrate 7 is one of zirconium oxide, aluminum oxide or silicon dioxide.

[0043] Zirconia, alumina or silica offer superior mechanical properties, excellent thermal insulation and low thermal conductivity, as well as chemical inertness, making them more efficient;

[0044] In a feasible solution, the material of the insulating layer 4 is silicon dioxide.

[0045] Silicon dioxide can prevent current leakage and short circuit, ensuring the electrical safety of the micro hotplate; it has good thermal insulation properties, which helps to maintain the temperature stability of the micro hotplate during operation and reduce heat loss, while providing mechanical protection and enhancing the life of the micro hotplate.

[0046] In a feasible solution, the width of the cantilever beam 3 is one of 14 μm, 28 μm, and 42 μm.

[0047] In a feasible solution, the angle of the rounded corner 6 is 0.005 μm-0.020 μm.

[0048] In a feasible solution, the heating electrode 1 , the tooth electrode 2 and the temperature measuring electrode 5 are made of platinum electrode material.

[0049] In a feasible solution, the thickness of the heating electrode 1 , the tooth electrode 2 and the temperature measuring electrode 5 is 1 μm-3 μm.

[0050] In a feasible solution, the heating electrode 1 , the tooth electrode 2 and the temperature measuring electrode 5 are located on the same horizontal plane.

[0051] A method for making a micro-hotplate is used to make the above-mentioned micro-hotplate, and the steps are as follows: select a substrate 7 of set specifications, deposit an insulating layer 4 on the top surface of the substrate 7, etch and deposit a heating electrode 1, a tooth electrode 2 and a temperature measuring electrode 5 on the top surface of the insulating layer 4, use a micro-spraying film-forming method to attach a gas-sensitive film to the tooth electrode 2 for coating a gas-sensitive material, and laser-etch a hollow structure 8 according to the shape of the heating electrode 1, the tooth electrode 2, the temperature measuring electrode 5 and the hollow structure 8 to obtain a micro-hotplate.

[0052] Example 1

[0053] The length × width of the micro-hotplate is 0.6 mm × 0.6 mm, the thickness is 70 μm, and the size of the central heat source area is 0.22 mm × 0.22 mm;

[0054] The material of the substrate 7 is zirconium oxide, the insulating layer 4 is silicon dioxide, the width of the cantilever beam 3 is 28 μm, the angle of the fillet 6 is 0.005 μm, the thickness of the heating electrode 1, the tooth electrode 2, and the temperature measuring electrode 5 are all 2 μm, the tooth electrode 2 includes a tooth and a gas sensitive film covering the tooth, and the gas sensitive film is a metal oxide. The electrode width of the heating electrode 1 is 0.014 mm, the electrode spacing is 0.0325 mm, the middle electrode length is 0.109 mm, the spacing between the heating electrode 1 and the tooth electrode 2 is 0.014 mm, and the heating electrode 1 and The spacing between the temperature measuring electrodes 5 is 0.0065mm; the electrode width of the tooth electrode 2 is 0.005mm, the electrode spacing is 0.004mm, and the electrode lengths are 0.135mm, 0.130mm and 0.1515mm; the electrode widths of the temperature measuring electrode 5 are 0.005mm and 0.0065mm, the electrode spacing is 0.004mm and 0.0065mm, and the electrode lengths are 0.1526mm, 0.133mm, 0.1145mm, 0.1015mm, 0.100mm and 0.095mm.

[0055] Example 2

[0056] The difference between this embodiment and embodiment 1 is that the micro-hotplate has a thickness of 100 μm, the cantilever beam 3 has a width of 14 μm, the fillet 6 has an angle of 0.015 μm, and the distribution states of the heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 are as follows: Figure 5 As shown;

[0057] Example 3

[0058] The difference between this embodiment and embodiment 1 is that the thickness of the micro-hotplate is 100 μm, the width of the cantilever beam is 14 μm, the angle of the fillet 6 is 0.010 μm, and the distribution states of the heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 are as follows: Figure 6 As shown;

[0059] In the present invention, the heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 are located in the same plane and are cross-distributed, so that the temperature increases faster, so that the tooth electrode 2 can better receive heat, so that the gas sensor can respond faster and operate with lower power consumption; the heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 do not contact each other, avoiding the influence of circuit crosstalk between the electrodes of the laminated micro-hot plate;

[0060] An insulating layer 4 is provided above the substrate 7, and the insulating layer 4 separates the substrate 7 from the heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5, which can prevent current leakage and short circuit, and ensure the electrical safety of the micro-hotplate; it has good thermal insulation performance, which helps to maintain the temperature stability of the micro-hotplate during operation, reduce heat loss, and provide mechanical protection, thereby enhancing the life of the micro-hotplate;

[0061] By setting the hollow structure 8, the cantilever beam 3 and the rounded corner 6, the heat conduction area is reduced to reduce the thermal stress, and the life of the cantilever beam 3 is enhanced, which effectively avoids the phenomenon that the micro-hot plate is broken due to stress accumulation under the action of thermal stress, improves the reliability and stability of the micro-hot plate structure, and enables the micro-hot plate to be used efficiently in various occasions;

[0062] The substrate 7 is made of zirconium oxide material, which has a low thermal expansion coefficient, helps to reduce thermal stress caused by temperature changes, improves the thermal shock resistance of the micro-hotplate, and has good chemical stability, is not easily damaged in a variety of environments, and improves the tolerance of the micro-hotplate;

[0063] A hollow structure 8 is provided on the substrate 7, which helps to slow down the rapid loss of heat, thereby increasing the heating speed of the heating unit and reducing energy consumption;

[0064] The heating electrode 1, the tooth electrode 2 and the temperature measuring electrode 5 are located on the same horizontal plane, and the electrodes are led out by two pins respectively. By changing the electrode arrangement pattern, electrode width and electrode spacing and other conditions, the temperature uniformity and stress distribution of the micro-hotplate are improved.

[0065] The present invention designs a micro-hotplate structure. By selecting the material of the substrate 7, adjusting the width of the cantilever beam 3 and the structural angle of the fillet 6, and changing the electrode distribution pattern, a hollow micro-hotplate structure with low power consumption, high efficiency, good temperature uniformity and stress distribution is obtained. The micro-hotplate is mass-produced, which provides great help on the road of integration, miniaturization and high efficiency of MEMS gas sensors. The production and use efficiency of MEMS gas sensors is improved.

[0066] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0067] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A micro hot plate, characterized in that: include: A substrate (7), wherein an insulating layer (4) is arranged on the top surface of the substrate (7), and a plurality of hollow structures (8) are arranged circumferentially and evenly spaced on the substrate (7), a cantilever beam (3) is formed between two adjacent hollow structures (8), the hollow structure (8) passes through the insulating layer (4), a heating electrode (1), a tooth electrode (2) and a temperature measuring electrode (5) are integrated on the top surface of the insulating layer (4), the heating electrode (1), the tooth electrode (2) and the temperature measuring electrode (5) are all located outside the plurality of hollow structures (8), the pins of the heating electrode (1), the tooth electrode (2) and the temperature measuring electrode (5) respectively pass through the plurality of cantilever beams (3) and are located inside the plurality of hollow structures (8), and the corners of the hollow structures (8) are configured as rounded corners (6).

2. A micro hot plate according to claim 1, characterized in that: The material of the substrate (7) is one of zirconium oxide, aluminum oxide or silicon dioxide.

3. A micro hot plate according to claim 1, characterized in that: The material of the insulating layer (4) is silicon dioxide.

4. A micro hot plate according to claim 1, characterized in that: The width of the cantilever beam (3) is one of 14 μm, 28 μm and 42 μm.

5. A micro-hotplate according to claim 1, characterized in that: The angle of the fillet (6) is 0.005 μm-0.020 μm.

6. A micro-hotplate according to claim 1, characterized in that: The heating electrode (1), the tooth electrode (2) and the temperature measuring electrode (5) are made of platinum electrode material.

7. A micro-hotplate according to claim 1, characterized in that: The thickness of the heating electrode (1), the tooth electrode (2) and the temperature measuring electrode (5) is 1 μm-3 μm.

8. A micro-hotplate according to claim 1, characterized in that: The heating electrode (1), the tooth-inserting electrode (2) and the temperature measuring electrode (5) are located on the same horizontal plane.

9. A method for manufacturing a micro-hotplate, used for manufacturing the micro-hotplate according to any one of claims 1 to 8, characterized in that: The steps are as follows: selecting a substrate (7) of set specifications, depositing an insulating layer (4) on the top surface of the substrate (7), etching and depositing a heating electrode (1), a tooth electrode (2) and a temperature measuring electrode (5) on the top surface of the insulating layer (4), using a micro-spraying film-forming method to attach a gas-sensitive film to the tooth electrode (2) for coating a gas-sensitive material, and laser etching a hollow structure (8) according to the shapes of the heating electrode (1), the tooth electrode (2), the temperature measuring electrode (5) and the hollow structure (8) to obtain a micro-hotplate.

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