Preparation method of a micro heater

Abstract

The present invention discloses a preparation method of a micro heater, which includes a substrate having an etching groove; a composite support layer covering the entire substrate; a heating layer deposited on the upper surface of the composite support layer; a protective layer covering the heating structure; a passivation layer covering the heating layer and the protective layer; a metal heat dissipation layer disposed inside the passivation layer; the method includes: forming a composite support layer on the upper surface of the substrate; depositing a heating layer on the upper surface of the composite support layer; depositing a protective layer for covering the heating structure on the heating structure of the heating layer; depositing a passivation layer on the upper surface of the composite support layer; depositing a metal heat dissipation layer on the upper surface of the passivation layer; continuously depositing the passivation layer to a predetermined thickness to wrap the metal heat dissipation layer; etching a window in the passivation layer, and depositing a Pad layer on the upper surface of the exposed connection electrode; etching the substrate to form an etching groove. The thin film structure of this micro heater is stable, has good heat dissipation performance, and short thermal response time, solving the problem that traditional micro heaters cannot balance the thermal response rate and structural stability.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS, and particularly to a method for fabricating a micro heater. Background Art

[0002] A MEMS Heater is a micro heating element based on MEMS (Micro-Electro-Mechanical Systems) technology, which is widely used in advanced technology fields such as gas sensors, microfluidic systems, environmental monitoring, and broadband infrared emission. They have become an indispensable component in modern technology due to their advantages such as small size, fast response, and low power consumption. By integrating a micro-resistance heating element, MEMS Heater can achieve precise temperature control and efficient thermal management. In recent years, with the continuous progress of MEMS technology, the design and performance of these heaters have been significantly improved, showing excellent performance not only in traditional application fields but also in emerging broadband infrared emission applications.

[0003] In the design of MEMS Heater, there are two existing mature structural modes, namely the void structure and the cantilever beam structure. The void structure uses a complete support film and designs a thermal insulation air cavity under the film. This design provides effective thermal insulation through the air cavity, reducing heat conduction to the substrate and thus improving the heating efficiency. The cantilever beam structure connects the heating area to the silicon substrate through several cantilever beams, and uses deep silicon etching (DSI) technology to remove materials on the back of the silicon substrate to reduce heat dissipation through the substrate.

[0004] Currently, the void-type micro heater has problems of more heat loss and longer thermal response time. The cantilever beam-type micro heater has defects of fragile film structure and poor device stability. Although the improved cantilever beam-type micro heater usually uses a thicker silicon dioxide deposited on the upper layer to protect the film structure, this also introduces problems such as extended heat dissipation time and increased thermal stress. The thicker silicon dioxide layer can provide physical protection, but it affects the heat dissipation speed, resulting in a longer cooling response time, and at the same time increases the thermal stress in the structure, which also has a negative impact on the stability of the micro heater. Summary of the Invention

[0005] Aiming at the above-mentioned defects existing in the prior art, one of the present inventions provides a micro heater to solve the problem that traditional micro heaters cannot balance the thermal response rate and structural stability.

[0006] One of the present inventions is realized by the following technical solutions:

[0007] A micro heater, comprising:

[0008] A substrate having an etching groove;

[0009] A composite support layer covering the upper surface of the substrate;

[0010] A heating layer having a heating structure deposited on the upper surface of the composite support layer and connecting electrodes led out;

[0011] A protective layer for covering the heating structure of the heating layer;

[0012] A passivation layer for covering the heating layer and the protective layer;

[0013] A metal heat dissipation layer disposed inside the passivation layer.

[0014] Further, the composite support layer is made of silicon dioxide material and aluminum nitride material, and the protective layer is made of aluminum nitride material.

[0015] Further, the heating structure is made of molybdenum material.

[0016] Further, the metal heat dissipation layer is made of molybdenum material.

[0017] Further, the heating structure is a double heating electrode, and each heating electrode includes a plurality of arc portions and a plurality of connecting portions configured to connect the arc portions, and the double heating electrodes are combined into a circular structure.

[0018] Further, the connecting portion includes a transverse connecting portion and a longitudinal connecting portion that are vertically connected. One end of the transverse connecting portion away from the longitudinal connecting portion and one end of the longitudinal connecting portion away from the transverse connecting portion are respectively connected with a connecting electrode. One side of the transverse connecting portion and the longitudinal connecting portion are both connected with a first arc portion formed in an arc shape, a first connecting portion bent inward toward the center of the circle at one end of the first arc portion, a second arc portion formed in an arc shape and extending from the end of the first connecting portion and spaced inward from the first arc portion. The other side of the transverse connecting portion and the longitudinal connecting portion are both connected with a third arc portion formed in an arc shape, a second connecting portion bent inward toward the center of the circle at one end of the third arc portion, a fourth arc portion formed in an arc shape and extending from the end of the second connecting portion and spaced inward from the third arc portion. The arc lengths of the first arc portion, the second arc portion, the third arc portion, and the fourth arc portion gradually decrease from the outside to the inside.

[0019] Further, it further includes a Pad layer. The passivation layer is provided with a window exposing the connecting electrode of the heating layer, and the Pad layer is used to cover the connecting electrode of the heating layer from the window.

[0020] The second aspect of the present invention provides a method for manufacturing a micro heater, which can improve the structural stability and thermal response rate of the micro heater, and also reduce the manufacturing cost.

[0021] The second aspect of the present invention is realized by the following technical solutions:

[0022] A method for manufacturing a micro heater, including the above-mentioned micro heater, the steps are as follows:

[0023] S10. Deposit and form a composite support layer on the upper surface of the substrate;

[0024] S20. Deposit a heating layer on the upper surface of the composite support layer, and then pattern-etch the heating structure of the heating layer;

[0025] S30. Deposit and form a protective layer on the heating structure of the heating layer to cover the heating structure;

[0026] S40. Deposit and form a passivation layer on the upper surface of the composite support layer to completely cover the heating layer and the protective layer;

[0027] S50. Deposit and form a metal heat dissipation layer on the upper surface of the passivation layer;

[0028] S60. Continuously deposit the upper surface of the passivation layer to a predetermined thickness to wrap the metal heat dissipation layer inside the passivation layer;

[0029] S70. Etch a window on the passivation layer to expose the connection electrode of the heating layer, and deposit and form a Pad layer on the upper surface of the exposed connection electrode;

[0030] S80. Etch the substrate from the lower surface along its thickness direction to form an etching groove to expose the composite support layer.

[0031] Further, in step S10, the method for generating the composite support layer is as follows: First, generate an upper isolation layer and a lower isolation layer on the upper surface and the lower surface of the substrate by a thermal oxidation method, and then continue to deposit and generate a composite support upper layer on the upper surface of the upper isolation layer by a plasma-enhanced chemical vapor deposition method. The upper isolation layer (12) and the composite support upper layer together constitute the composite support layer.

[0032] Further, the thickness of the deposited composite support upper layer is the same as the thickness of the deposited protective layer.

[0033] Compared with the prior art, the beneficial effects of the present invention at least include:

[0034] (1) The micro - heater of the present invention adds multiple heat - dissipation structures to the thin - film structure of the traditional micro - heater, namely a composite support layer, a protective layer, and a metal heat - dissipation layer. The added composite support layer, protective layer, and metal heat - dissipation layer not only further thicken the thin - film structure, enhance the stability of the micro - heater, but also accelerate the heat - dissipation time, have good heat - dissipation performance, short thermal response time, and improve the thermal response rate. The composite support layer and the protective layer not only play a role in heat dissipation, but also can act as thermal stress protection, effectively reducing the stress problem caused by thermal expansion of the heating layer and further improving the structural stability.

[0035] (2) The micro - heater of the present invention selects non - traditional micro - heater materials such as molybdenum and aluminum nitride. On the premise of enhancing the structural stability, it has the effect of improving the thermal response rate, and at the same time reduces power consumption and cost.

[0036] (3) The micro - heater of the present invention uses a double - electrode structure for heating, and the double - electrode structure is made of molybdenum material, which can improve the thermal efficiency and response speed, ensure that the heater can achieve excellent performance under various working conditions, and thus meet higher application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is an exploded view of the micro - heater of the embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of the heating pattern of the heating structure of the embodiment of the invention;

[0039] Figure 3 is a schematic diagram of generating the upper isolation layer and the lower isolation layer in the preparation method of the micro - heater of the embodiment of the invention;

[0040] Figure 4 is a schematic diagram of generating the upper composite support layer in the preparation method of the micro - heater of the embodiment of the invention;

[0041] Figure 5 is a schematic diagram of generating the heating layer in the preparation method of the micro - heater of the embodiment of the invention;

[0042] Figure 6 is a schematic diagram of generating the protective layer in the preparation method of the micro - heater of the embodiment of the invention;

[0043] Figure 7 is a schematic diagram of generating the passivation layer and the metal heat - dissipation layer in the preparation method of the micro - heater of the embodiment of the invention;

[0044] Figure 8 is a schematic diagram of continuously depositing the passivation layer in the preparation method of the micro - heater of the embodiment of the invention;

[0045] Figure 9Schematic diagrams of steps 70 and 80 in the preparation method of the micro heater according to the invention embodiment;

[0046] In the figure: 1, substrate; 11, etching groove; 12, upper isolation layer; 13, lower isolation layer; 14, composite support upper layer; 2, composite support layer; 3, heating layer; 31, heating structure; 3100, transverse connection part; 3101, longitudinal connection part; 3102, first arc part; 3103, first connection part; 3104, second arc part; 3105, third arc part; 3106, second connection part; 3107, fourth arc part; 32, connection electrode; 4, protective layer; 5, passivation layer; 51, window; 6, metal heat dissipation layer; 7, Pad layer. Detailed implementation manners

[0047] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this invention will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals in the figures denote the same or similar structures, and thus their repetitive description will be omitted.

[0048] In the present invention, the words expressing position and direction are described with reference to the accompanying drawings as examples, but can be changed as needed, and all changes made are included in the protection scope of the present invention.

[0049] As Figure 1 and Figure 2 shown, a micro heater provided by the present invention includes:

[0050] A substrate 1 having an etching groove 11;

[0051] A composite support layer 2 covering the upper surface of the substrate 1;

[0052] A heating layer 3 having a heating structure 31 deposited on the upper surface of the composite support layer 2 and a lead-out connection electrode 32;

[0053] A protective layer 4 for covering the heating structure 31 of the heating layer 3;

[0054] A passivation layer 5 for covering the heating layer 3 and the protective layer 4;

[0055] A metal heat dissipation layer 6 provided inside the passivation layer 5.

[0056] In this embodiment, by providing an etching groove 11 in the substrate 1, the heat generated by the heating layer 3 can be locally concentrated, significantly reducing heat dissipation and improving energy efficiency, and showing better thermal performance in applications requiring precise temperature control. The composite support layer 2 covers the upper surface of the substrate 1, can stably support the upper structure, and can play a role in heat dissipation. At the same time, the composite support layer 2 can also play a role in thermal stress protection. Therefore, the composite support layer 2 can be used as the bottom heat dissipation structure and thermal stress protection structure. The protective layer 4 covers the heating structure 31 of the heating layer 3 and can play a role in heat dissipation as the middle heat dissipation structure. The metal heat dissipation layer 6 is disposed inside the passivation layer 5. Since the passivation layer 5 has a relatively thick layer thickness, resulting in poor heat dissipation performance, a metal heat dissipation layer 6 is added in the middle of the passivation layer 5 as the top heat dissipation structure. Since the metal heat dissipation layer 6 is wrapped by the passivation layer 5, it can maintain the chemical stability and electrical insulation of the material, preventing oxidation or other environmental effects of the metal heat dissipation layer 6. Therefore, the metal heat dissipation layer 6 as an additional heat dissipation structure can compensate for the problem of the longer thermal response time caused by the thicker passivation layer 5.

[0057] Therefore, the micro-heater of the present invention adds multiple heat dissipation structures in the thin film structure of the traditional micro-heater, namely the composite support layer 2, the protective layer 4 and the metal heat dissipation layer 6. The added composite support layer 2, protective layer 4 and metal heat dissipation layer 6 not only further thicken the thin film structure, enhance the stability of the micro-heater, but also accelerate the heat dissipation time, improve the heat dissipation effect, and have a short thermal response time, improving the thermal response rate. The composite support layer 2 and the protective layer 4 not only act as heat dissipation structures together, but also can act as thermal stress protection, effectively reducing the stress problem caused by thermal expansion of the heating layer 3 and further improving the stability of the structure.

[0058] As a preferred embodiment, the composite support layer 2 is made of silicon dioxide and aluminum nitride, and the protective layer 4 is made of aluminum nitride.

[0059] In this embodiment, the composite support layer 2 is made of silicon dioxide and aluminum nitride. Since aluminum nitride has good thermal conductivity, heat can be conducted more efficiently, and at the same time, the effect of thermal stress management can be improved.

[0060] As a preferred embodiment, the heating structure 31 is made of molybdenum.

[0061] The composite support upper layer 14 and the protective layer 4 made of aluminum nitride in this embodiment covering the heating structure 31 made of molybdenum exhibit better functions compared to traditional silicon nitride materials. Specifically, it is manifested in that: molybdenum not only has a lower cost and good thermal conductivity, but also can maintain better stability and consume lower power under high-temperature conditions. Compared with the heating materials of traditional micro heaters, without losing thermal stability, it also reduces power consumption and manufacturing costs. In addition, the thermal expansion coefficients of aluminum nitride and molybdenum are similar at high temperatures, which makes the entire micro heater more stable and reliable, and is particularly suitable for high-performance applications that require efficient thermal management. Although molybdenum is an uncommon resistance material, its thermal expansion coefficient does not match that of common MEMS materials such as silicon, which may cause stress during the thermal cycle, resulting in material layer peeling or structural failure. At the same time, molybdenum is prone to oxidation at high temperatures and is not suitable as a high-temperature heating material. However, the advantages of molybdenum are also obvious. Molybdenum has a high melting point and high enough thermal stability. Its resistivity and temperature resistance coefficient are higher than those of traditional resistance materials, and the power consumption is smaller. At the same time, the manufacturing cost of molybdenum is relatively low, effectively controlling the overall cost of the device. The present invention makes full use of the advantages of molybdenum materials and effectively compensates for their disadvantages.

[0062] As a preferred embodiment, the metal heat dissipation layer 6 is made of molybdenum.

[0063] In the present invention, the main function of the metal heat dissipation layer 6 is to dissipate heat from the passivation layer 5 to shorten the thermal response time. Molybdenum has a high melting point and high enough thermal stability. Its resistivity and temperature resistance coefficient are higher than those of traditional resistance materials, and the power consumption is smaller. At the same time, the manufacturing cost of molybdenum is relatively low, effectively controlling the overall cost of the device. Of course, the metal heat dissipation layer 6 can also be replaced by any metal or material with good heat dissipation performance, such as platinum, tungsten, etc. The shape of the metal heat dissipation layer 6 and the shape of the protective layer 4 in this embodiment are preferably circular, so as to match and cover the heating electrodes of the circular structure. Of course, in other embodiments, the shapes of the metal heat dissipation layer 6 and the protective layer 4 can also be designed into different shapes as long as the purpose of the present invention is achieved.

[0064] As a preferred embodiment, the heating structure 31 is a double heating electrode, and each heating electrode includes a plurality of arc portions and a plurality of connecting portions configured to connect the arc portions, and the double heating electrodes are combined into a circular structure.

[0065] In this embodiment, the heating structure 31 is a double heating electrode. Through the optimized design of the structure of the double heating electrode, compared with the traditional electrode that mostly uses a single resistor and has a spiral shape, the double heating electrode of the present invention has a circular structure, and the circular structure is composed of a plurality of arc portions and a plurality of connecting portions. The arc portions increase the heating area, enabling the micro-heater to obtain a large-area and high-quality uniform temperature region during operation, with higher reliability, reducing the phenomenon of local overheating caused by current concentration, and thus extending the device life. Therefore, the heating structure 31 of the double heating electrode of the present invention can improve the thermal efficiency and response speed, significantly enhancing the performance of the micro-heater, ensuring that the heater can achieve excellent performance under various working conditions, and thus meeting higher application requirements.

[0066] As a preferred embodiment, the connecting portion includes a horizontal connecting portion 3100 and a vertical connecting portion 3101 that are vertically connected. One end of the horizontal connecting portion 3100 away from the vertical connecting portion 3101 and one end of the vertical connecting portion 3101 away from the horizontal connecting portion 3100 are respectively connected to a connecting electrode 32. One side of the horizontal connecting portion 3100 and the vertical connecting portion 3101 are both connected to a first arc portion 3102 formed in an arc shape, a first connecting portion 3103 that bends inward toward the center of the circle at one end of the first arc portion 3102, and a second arc portion 3104 formed in an arc shape that extends from the end of the first connecting portion 3103 and is spaced inward from the first arc portion 3102. The other side of the horizontal connecting portion 3100 and the vertical connecting portion 3101 are both connected to a third arc portion 3105 formed in an arc shape, a second connecting portion 3106 that bends inward toward the center of the circle at one end of the third arc portion 3105, and a fourth arc portion 3107 formed in an arc shape that extends from the end of the second connecting portion 3106 and is spaced inward from the third arc portion 3105. The arc lengths of the first arc portion 3102, the second arc portion 3104, the third arc portion 3105, and the fourth arc portion 3107 gradually decrease from the outside to the inside.

[0067] In this embodiment, by providing the first arc portion 3102, the second arc portion 3104, the third arc portion 3105 and the fourth arc portion 3107, and connecting the above-mentioned arc portions through the horizontal connecting portion 3100, the vertical connecting portion 3101, the first connecting portion 3103 and the second connecting portion 3106, and the arc lengths of the above-mentioned arc portions gradually decrease from outside to inside, the first arc portion 3102 and the second arc portion 3104 are arranged at intervals, the third arc portion 3105 and the fourth arc portion 3107 are arranged at intervals, and the double heating electrodes are combined to form a circular structure with multiple circles arranged at intervals that expands from inside to outside, so that a more uniform current distribution can be provided, a more uniform heating effect can be achieved, and the uniformity of the heating temperature can be ensured. The shapes of the double heating electrodes are the same, which is convenient for the two to have the same heat generation amount and ensure the uniformity of the temperature.

[0068] As a preferred embodiment, it further includes a Pad layer 7. The passivation layer 5 is provided with a window 51 exposing the connection electrode 32 of the heating layer 3, and the Pad layer 7 is used to cover the connection electrode 32 of the heating layer 3 from the window 51.

[0069] In this embodiment, the passivation layer 5 is etched to form the window 51 to expose the connection electrode 32 of the heating layer 3, which is convenient for connecting metal leads during testing. Using the Pad layer 7 to cover the exposed connection electrode 32 can prevent the oxidation of the heating layer 3. At the same time, the Pad layer 7 can seal the heating layer 3 and isolate oxygen to prevent the oxidation of the molybdenum material at high temperatures, thereby effectively compensating for the disadvantages of the molybdenum material. The Pad layer 7 is preferably made of gold. Of course, in other embodiments, the Pad layer 7 can also be made of other materials that isolate oxygen.

[0070] As Figures 3 - 9 shown, a preparation method of a micro heater according to the present invention has the following steps:

[0071] S10. Deposit and form a composite support layer 2 on the upper surface of the substrate 1;

[0072] S20. Deposit a heating layer 3 on the upper surface of the composite support layer 2, and then pattern the heating structure 31 of the heating layer 3;

[0073] S30. Deposit and form a protective layer 4 on the heating structure 31 of the heating layer 3 to cover the heating structure 31;

[0074] S40. Deposit and form a passivation layer 5 on the upper surface of the composite support layer 2 to completely cover the heating layer 3 and the protective layer 4;

[0075] S50. Deposit and form a metal heat dissipation layer 6 on the upper surface of the passivation layer 5;

[0076] S60. Continuously deposit a predetermined thickness on the upper surface of the passivation layer 5 to wrap the metal heat dissipation layer 6 inside the passivation layer 5;

[0077] S70. Etch a window 51 in the passivation layer 5 to expose the connection electrode 32 of the heating layer 3; deposit and form a Pad layer 7 on the upper surface of the exposed Pad portion;

[0078] S80. Etch the substrate 1 from the lower surface along its thickness direction to form an etching groove 11 and expose the composite support layer 2.

[0079] In the present invention, in step S10, an upper isolation layer 12 and a lower isolation layer 13 are simultaneously formed on the upper surface and the lower surface of the substrate 1 by a thermal oxidation method, and then a composite support upper layer 14 is continuously deposited on the upper surface of the upper isolation layer 12 by a plasma enhanced chemical vapor deposition method. The upper isolation layer 12 and the composite support upper layer 14 together constitute the composite support layer 2. Among them, the upper isolation layer 12 and the lower isolation layer 13 are made of silicon dioxide material. In this way, the composite support layer 2 integrates a composite support structure composed of silicon dioxide and aluminum nitride. The composite support layer 2 provides mechanical stability, and at the same time has the functions of accelerating heat dissipation and thermal stress protection. Therefore, the composite support layer 2 serves as a bottom layer heat dissipation structure and a thermal stress protection structure. The design of this layer ensures the stability of the micro-heater in a high-temperature working environment and effectively reduces the influence of thermal stress on the device performance and service life. The lower isolation layer 13 can thicken the substrate 1 to enhance the structural stability of the entire micro-heater.

[0080] In step S20, a heating layer 3 is deposited on the upper surface of the composite support upper layer 14 by a plasma enhanced chemical vapor deposition method. Among them, the heating structure 31 of the heating layer 3 can be patterned by a wet etching method or a dry etching method. Finally, the heating structure 31 plays a role in heating up. Among them, the heating structure 31 of the heating layer 3 is preferably made of molybdenum material. The protective layer 4 of the aluminum nitride material composite support upper layer 14 wraps the molybdenum material heating structure 31. The aluminum nitride combined with the molybdenum material heating layer 3 shows better functions compared with the traditional silicon nitride material. Aluminum nitride has good thermal conductivity, enabling heat to be conducted more efficiently, and at the same time can improve the effect of thermal stress management. In addition, the thermal expansion coefficients of aluminum nitride and molybdenum are similar at high temperatures, which makes the entire micro-heater more durable and is particularly suitable for high-performance applications that require efficient thermal management.

[0081] The material of the heating structure 31 of the present invention is molybdenum. Molybdenum is an uncommon resistive material, and its coefficient of thermal expansion does not match that of common MEMS materials such as silicon, which may cause stress during the thermal cycle, resulting in delamination of the material layer or structural failure. At the same time, molybdenum is prone to oxidation at high temperatures and is not suitable as a high-temperature heating material. However, the advantages of molybdenum are also relatively obvious. Molybdenum has a high melting point and sufficient high thermal stability. Its resistivity and temperature coefficient of resistance are higher than those of the resistive materials of traditional micro heaters, and the power consumption is smaller. At the same time, the manufacturing cost of molybdenum is relatively low, which makes the economy of molybdenum in micro heaters more attractive. Therefore, the present invention makes full use of the advantages of molybdenum and effectively compensates for its disadvantages. As the heating layer 3, molybdenum not only has a low cost and good thermal conductivity, but also can maintain better stability and consume lower power under high-temperature conditions.

[0082] In step S30, the protective layer 4 is made of aluminum nitride. The protective layer 4 is deposited on the heating structure 31 by plasma-enhanced chemical vapor deposition. The protective layer 4 only covers the heating structure 31, and the protective layer 4 serves as a thermal stress protection structure and a heat dissipation structure for the middle layer. Among them, the shape of the protective layer 4 is not limited to the circular shape provided by the present invention. The larger the area of the protective layer 4, the better the heat dissipation. However, the problems to be considered are: if the heat dissipation is too large, it will cause the maximum temperature during heating to decrease and the heating time to increase. Therefore, the area of the protective layer 4 should not be too large or too small.

[0083] In step S40, a passivation layer 5 is deposited on the upper surface of the composite support layer 2 by plasma-enhanced chemical vapor deposition. Among them, the passivation layer 5 can be made of silicon dioxide. Of course, in other embodiments, the passivation layer 5 can also be any other common protective material. The passivation layer 5 in this step completely covers the heating layer 3 and the protective layer 4.

[0084] In step S50, a metal heat dissipation layer 6 is formed on the upper surface of the passivation layer 5 generated in step S40 by plasma enhanced chemical vapor deposition. In step S60, the passivation layer 5 is deposited on the basis of step S50 to reach a predetermined thickness, so as to protect the surface structure and thicken the entire thin film layer. In this step S60, the passivation layer 5 completely covers the metal heat dissipation layer 6, the heating layer 3 and the protective layer 4. The metal heat dissipation layer 6 is wrapped by the passivation layer 5, which can maintain the chemical stability and electrical insulation of the material, prevent the oxidation of the metal heat dissipation layer 6 or other environmental influences. At the same time, due to the relatively thick thickness of the passivation layer 5, the heat dissipation performance is poor. Therefore, adding the metal heat dissipation layer 6 in the middle of the passivation layer 5 can improve the thermal response time. Therefore, the metal heat dissipation layer 6 as the top heat dissipation structure can make up for the problem of the lengthened thermal response time caused by the relatively thick passivation layer 5. In addition, in order to improve the heat dissipation effect, the metal heat dissipation layer 6 should be made of a material with good heat dissipation performance. The metal heat dissipation layer 6 is preferably made of molybdenum. In other embodiments, the metal heat dissipation layer 6 can also be replaced by any metal or material with good heat dissipation performance, such as platinum, tungsten, etc.

[0085] In step S70, the passivation layer 5 is etched to expose the connection electrode 32 of the heating layer 3. A Pad layer 7 is formed on the upper surface of the exposed connection electrode 32 by sputtering. The Pad layer 7 covers the exposed connection electrode 32, thereby preventing the oxidation of the heating layer 3. The Pad layer 7 in this embodiment is preferably made of gold. The gold material has good electrical conductivity and better oxygen isolation effect, preventing the oxidation of the heating layer 3 at high temperature, thus effectively making up for the shortcomings of the molybdenum material.

[0086] In step 80, deep silicon etching is performed on the substrate 1 to etch an etching groove 11 on the substrate 1, exposing the composite support layer 2, and the upper layer structure is isolated and protected by the composite support layer 2. Among them, the etching groove 11 can be of any shape, and the larger the area, the better the heat dissipation performance.

[0087] As a preferred embodiment, the deposition thickness of the composite support upper layer 14 is the same as the deposition thickness of the protective layer 4.

[0088] In this embodiment, in order to ensure the corresponding stress relationship between the heating layer 3 and the composite support upper layer 14 and the protective layer 4, the deposition thicknesses of the composite support upper layer 14 and the protective layer 4 are the same. In this way, the heat dissipation effect can be further improved, and at the same time, the thin film can be thickened to enhance the structural stability.

[0089] In summary, the micro heater of the present invention adds multiple heat dissipation structures to the thin film structure of the traditional micro heater, namely the composite support upper layer 14, the protective layer 4 and the metal heat dissipation layer 6. The added heat dissipation structures not only further thicken the thin film structure and enhance the stability of the micro heater, but also accelerate the heat dissipation time due to the heat conduction performance of the structural materials, and the thermal response rate is significantly improved. In addition, the composite support upper layer 14 and the protective layer 4 not only serve as heat dissipation structures, but also as thermal stress protection structures, reducing the stress problem caused by thermal expansion of the heating layer 3 and further improving the structural stability. The heating layer 3 is made of molybdenum, and the protective layer 4 and the composite support upper layer 14 are made of aluminum nitride. Compared with the materials used in traditional micro heaters, it has the effects of enhancing heat dissipation performance and improving thermal response time on the premise of enhancing structural stability, while also reducing power consumption and cost.

[0090] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Without departing from the principle and purpose of the present invention, those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a micro heater, characterized in that: The steps are: S10, depositing a composite support layer (2) on the upper surface of the substrate (1); the method for generating the composite support layer (2) is as follows: firstly generating an upper isolation layer (12) and a lower isolation layer (13) on the upper surface and the lower surface of the substrate (1), respectively, and then depositing a composite support upper layer (14) on the upper surface of the upper isolation layer (12), wherein the upper isolation layer (12) and the composite support upper layer (14) together constitute the composite support layer (2), wherein the composite support upper layer (14) is made of aluminum nitride material, and the upper isolation layer (12) is made of silicon dioxide material; S20, depositing a heating layer (3) on the upper surface of the composite support upper layer (14), and then patterning the heating structure (31) of the heating layer (3); the heating structure (31) is a double heating electrode, each of the heating electrodes comprises a plurality of arc-shaped portions and a plurality of connecting portions configured to connect the arc-shaped portions, and the double heating electrodes are combined into a circular structure; S30, depositing a protective layer (4) on the heating structure (31) of the heating layer (3) to cover the heating structure (31), wherein the protective layer (4) is made of aluminum nitride; S40, depositing a passivation layer (5) on the upper surface of the composite support upper layer (14) to fully cover the heating layer (3) and the protective layer (4); S50, depositing a metal heat dissipation layer (6) on the upper surface of the passivation layer (5), wherein the metal heat dissipation layer (6) is made of molybdenum; S60, the upper surface of the passivation layer (5) continues to be deposited to a predetermined thickness, so as to wrap the metal heat dissipation layer (6) inside the passivation layer (5); S70, etching a window (51) on the passivation layer (5) to expose the connection electrode (32) of the heating layer (3), and depositing a Pad layer (7) on the upper surface of the exposed connection electrode (32); S80, etching the substrate (1) from the lower surface of the substrate (1) along the thickness direction thereof to form an etching groove (11), exposing the upper isolation layer (12).

2. The method for preparing the micro heater according to claim 1, characterized in that: In step S10, the upper isolation layer (12) and the lower isolation layer (13) are generated by a thermal oxidation method, and the composite support upper layer (14) is generated by a plasma enhanced chemical vapor deposition method.

3. The method for preparing the micro heater according to claim 1, characterized in that: The thickness of the composite support upper layer (14) deposited is the same as the thickness of the protective layer (4) deposited.

4. The method for preparing a micro heater according to claim 1, characterized in that: The heating structure (31) is made of molybdenum.

5. The method for preparing a micro heater according to claim 1, characterized in that: The connecting portion comprises a transverse connecting portion (3100) and a longitudinal connecting portion (3101) which are vertically connected, wherein one end of the transverse connecting portion (3100) away from the longitudinal connecting portion (3101) and one end of the longitudinal connecting portion (3101) away from the transverse connecting portion (3100) are respectively connected to a connecting electrode (32), and one side of each of the transverse connecting portion (3100) and the longitudinal connecting portion (3101) is connected to a first arc-shaped portion (3102) formed in an arc shape, a first connecting portion (3103) which is bent at one end of the first arc-shaped portion (3102) to extend toward the inner side of the center of the circle, and a first arc-shaped portion (3103) which is formed in an arc shape to extend from an end of the first connecting portion (3103) and from the first arc-shaped portion (3102) is a second arc portion (3104) spaced inwardly from the second arc portion (3102), the other sides of the transverse connecting portion (3100) and the longitudinal connecting portion (3101) are connected to a third arc portion (3105) formed in an arc shape, a second connecting portion (3106) bent at one end of the third arc portion (3105) to extend inwardly toward the center of the circle, and a fourth arc portion (3107) formed in an arc shape to extend from the end of the second connecting portion (3106) and spaced inwardly from the third arc portion (3105), and the arc lengths of the first arc portion (3102), the second arc portion (3104), the third arc portion (3105) and the fourth arc portion (3107) gradually decrease from the outside to the inside.

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