A MEMS micro-heater based on nickel metal heating and a preparation method thereof

Abstract

The application relates to the technical field of semiconductor devices, in particular to a MEMS micro-heater based on nickel metal heating and a preparation method thereof. In order to solve the problems of the existing MEMS micro-heater in the aspects of heat energy concentration and heating response, a new MEMS micro-heater based on nickel metal heating is provided, which comprises a Si substrate, the back surface of the Si substrate is deposited with a first SiO2 film layer, the front surface of the Si substrate is deposited with a second SiO2 film layer, the surface of the second SiO2 film layer is deposited with a metal heating unit, the metal heating unit comprises a plurality of heating electrode strips and two lead electrode strips which are distributed side by side, each heating electrode strip and lead electrode strip is composed of an adhesion layer, a seed layer and a Ni metal heating layer which are sequentially deposited on the surface of the second SiO2 film layer. The heat energy concentration and the heating response of the MEMS micro-heater are higher.

Description

Technical Field

[0001] This invention relates to the field of semiconductor device technology, and in particular to MEMS micro heaters, specifically a MEMS micro heater based on nickel metal heating and its fabrication method. Background Technology

[0002] With the continuous improvement of micro-nano manufacturing technology and the integration of electronic devices, various precision miniaturized systems are widely used in communication, sensing, security, and military fields. To meet specific functional requirements, many micro-systems often need to achieve rapid local heating, high-temperature triggering, or thermally driven operation, such as thermal response sensors, micro-ignition devices, information self-destruct modules, and thermally induced actuators. MEMS micro-heaters, as key components for achieving localized heat release and temperature control, have received widespread attention in recent years.

[0003] Common MEMS microheaters are typically based on the principle of resistance heating, which utilizes the Joule heat generated by an energized conductive material to heat a localized area. Existing MEMS microheaters usually employ metal heating bridges, spiral coils, or serpentine electrode layouts in their structural design, along with thermally insulating substrates (such as silicon dioxide or silicon nitride) to improve heating efficiency and reduce heat diffusion. However, their heat concentration and heating response still need improvement. Summary of the Invention

[0004] In order to address the shortcomings of existing MEMS microheaters in terms of heat concentration and heating response, this invention provides a novel MEMS microheater based on nickel metal heating and its fabrication method.

[0005] This invention is achieved using the following technical solution:

[0006] A MEMS micro heater based on nickel metal heating includes a Si substrate. A first SiO2 thin film layer is deposited on the back side of the Si substrate, and a second SiO2 thin film layer is deposited on the front side of the Si substrate. A metal heating unit is deposited on the surface of the second SiO2 thin film layer. The metal heating unit includes multiple heating electrode strips arranged side by side and two lead electrode strips arranged front and back. The multiple heating electrode strips are all located between the two lead electrode strips, and both ends of each heating electrode strip are connected to the two lead electrode strips respectively. Each heating electrode strip and lead electrode strip consists of an adhesion layer, a seed layer, and a Ni metal heating layer electroplated on the seed layer, which are sequentially deposited on the surface of the second SiO2 thin film layer.

[0007] Principle Explanation: The MEMS micro-heater described in this invention primarily utilizes a Ni metal heating layer within a metal heating unit. Ni maintains stable resistance over a wide temperature range and possesses a high melting point, good oxidation resistance, and moderate thermal conductivity. Therefore, in high-temperature, rapid-response scenarios, this nickel-based MEMS micro-heater offers significant advantages for rapid localized temperature rise. Furthermore, the unique layout of the metal heating unit structure in this invention provides excellent heat concentration and heating responsiveness, making it well-suited for applications in micro-thermal drive systems, information self-destruct devices, or micro-ignition devices. In use, connecting the two lead electrode strips to an external circuit energizes the metal heating unit, enabling the MEMS micro-heater to perform its heating function. Temperature control of the MEMS micro-heater can be achieved by controlling the energizing current.

[0008] Furthermore, the width of the portion of the multiple heating electrode strips corresponding to the local area to be heated is narrower than the width of the rest. The thinner the portion of the heating electrode strip, the better the heat concentration and heating response.

[0009] Furthermore, each heating electrode strip is dumbbell-shaped with wide ends and narrow middle in a top view, which is suitable for occasions where rapid local heating is required in the middle.

[0010] Furthermore, the width of each heating electrode strip is 12 μm at both ends and 6 μm in the middle, with a spacing of 206 μm between the middle sections of two adjacent heating electrode strips. This structure is specific and standardized, which not only improves the thermal energy concentration and heating response of the MEMS micro heater, but also avoids the risk of breakage in the thinner parts of the heating electrode strip when the temperature is too high (because the thinner the heating electrode strip, the better the thermal energy concentration and heating response of the MEMS micro heater, but if the heating electrode strip is too thin, it will generate excessively high current density during operation, thereby aggravating local electromigration, interface oxidation and thermal stress concentration of the heating electrode strip, which can easily lead to local hot spots, voids or film fractures in the heating electrode strip).

[0011] Furthermore, the thickness of both the first SiO2 thin film layer and the second SiO2 thin film layer is 500 nm, the thickness of the Si substrate is 500 μm, the thickness of the adhesion layer is 10 nm, the thickness of the seed layer is 50 nm, and the thickness of the Ni metal heating layer is 1050 nm.

[0012] Furthermore, the adhesion layer is a Ti metal thin film layer.

[0013] Furthermore, the seed layer is a Ni metal thin film layer.

[0014] Furthermore, the two lead electrode strips are 12240 μm long and 400 μm wide.

[0015] The method for fabricating a MEMS microheater based on nickel metal heating, as described above, includes the following steps:

[0016] (a) The Si substrate is cleaned and dried with nitrogen gas, and a first SiO2 thin film layer and a second SiO2 thin film layer are deposited on the back side and the front side of the Si substrate, respectively.

[0017] (b) An adhesion layer and a seed layer are sequentially deposited on the surface of the second SiO2 thin film using a magnetron sputtering process;

[0018] (c) Spin-coating photoresist onto the surface of the seed layer;

[0019] (d) Place the mask containing the metal heating unit pattern on the photoresist, and then expose and develop it;

[0020] (e) An electroplating process is used to electroplat a Ni metal heating layer on the surface of the seed layer after exposure and development;

[0021] (f) Clean the remaining photoresist;

[0022] (h) The seed layer and adhesion layer with non-electroplated Ni metal heating layer are etched by etching process to complete the fabrication of MEMS micro heater.

[0023] Further, in step (e), the electroplating process uses an electroplating solution comprising 44 g / L NiCl2·6H2O, 35 ml / L boric acid, 1.5 g / L saccharin, and 0.4 g / L sodium dodecyl sulfate, with a current density of 5 mA / cm² during electroplating. 2 The electroplating time was 2 minutes and the electroplating rate was 500 nm / min.

[0024] The beneficial effects of this invention are as follows: The MEMS micro heater described in this invention effectively improves the thermal energy concentration and heating response of the MEMS micro heater by optimizing the geometric layout and thermal field distribution design of the metal heating unit, thereby improving the temperature uniformity and stability of the local area to be heated. Moreover, the structure is simplified, the manufacturing process is simple, the yield is high, and the manufacturing cost is low. In addition, as a high-temperature resistant actuator, this MEMS micro heater based on nickel metal heating has both a high melting point (1455℃) and oxidation resistance, making it suitable for functional scenarios such as micro thermal drive, information protection, and thermal triggering, providing an effective technical means for applications that require rapid high-temperature or localized heating. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of the MEMS microheater fabrication method described in this invention;

[0028] Figure 2 This is a schematic diagram of the metal heating unit in the MEMS micro heater described in this invention;

[0029] Figure 3 This is an enlarged structural schematic diagram of the heating electrode strip in the metal heating unit of the present invention;

[0030] Figure 4 This is a schematic diagram of the temperature response curves of the MEMS micro heater described in this invention under different driving currents (0.8A–1.8A);

[0031] Figure 5 This is a schematic diagram showing the voltage variation trend across the MEMS micro heater described in this invention under different driving currents (0.8A–1.8A).

[0032] Figure 6 Infrared thermal images of the surface of the MEMS micro heater described in this invention under different driving currents (0.8A–1.8A);

[0033] Figure 7 This is a schematic diagram of the temperature response curve of the MEMS micro heater under a driving current of 3A after replacing the electroplated Ni metal heating layer in the MEMS micro heater of the present invention with an Al metal heating layer.

[0034] Figure 8 This is a schematic diagram illustrating the explosion process of a porous silicon energetic chip triggered by the MEMS micro heater described in this invention after being activated by power.

[0035] In the diagram: 1-Heating electrode strip, 2-Lead electrode strip. Detailed Implementation

[0036] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0037] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0038] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0039] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] like Figure 2 and Figure 3 As shown, a MEMS micro heater based on nickel metal heating includes a Si substrate. A first SiO2 thin film layer is deposited on the back side of the Si substrate, and a second SiO2 thin film layer is deposited on the front side of the Si substrate. A metal heating unit is deposited on the surface of the second SiO2 thin film layer. The metal heating unit includes multiple heating electrode strips 1 arranged side by side and two lead electrode strips 2 arranged front to back. The multiple heating electrode strips 1 are all located between the two lead electrode strips 2, and both ends of each heating electrode strip 1 are respectively connected to the two lead electrode strips 2. Each heating electrode strip 1 and lead electrode strip 2 is composed of an adhesion layer, a seed layer and a Ni metal heating layer electroplated on the seed layer, which are sequentially deposited on the surface of the second SiO2 thin film layer.

[0041] Principle Explanation: The MEMS micro-heater of this invention primarily utilizes a Ni metal heating layer within a metal heating unit. Ni maintains stable resistance over a wide temperature range and possesses a high melting point, good oxidation resistance, and moderate thermal conductivity. Therefore, in high-temperature, rapid-response scenarios, this nickel-based MEMS micro-heater offers significant advantages for rapid localized temperature rise. Furthermore, the unique layout of the metal heating unit structure in this invention provides excellent heat concentration and heating responsiveness, making it well-suited for applications in micro-thermal drive systems, information self-destruct devices, or micro-ignition devices. In use, connecting the two lead electrode strips 2 to an external circuit energizes the metal heating unit, enabling the MEMS micro-heater to perform its heating function. Temperature control of the MEMS micro-heater can be achieved by controlling the energizing current.

[0042] In practice, the width of the portion of the multiple heating electrode strips 1 corresponding to the local area to be heated is narrower than the width of the rest. The thinner the heating electrode strips 1, the better the heat energy concentration and heating response of the heater.

[0043] In practice, each heating electrode strip 1 is dumbbell-shaped with wide ends and narrow middle in a top view, which is suitable for occasions where local rapid heating is required in the middle.

[0044] In specific implementation, the width of each heating electrode strip 1 is 12 μm at both ends and 6 μm in the middle, and the distance between the middle of two adjacent heating electrode strips 1 is 206 μm. The structure is specific and standardized, which not only improves the thermal energy concentration and heating response of the MEMS micro heater, but also avoids the breakage of the thinner part of the heating electrode strip 1 when the temperature is too high (because the thinner the heating electrode strip 1, the better the thermal energy concentration and heating response of the MEMS micro heater, but if the heating electrode strip 1 is too thin, it will generate excessively high current density during the power-on operation, thereby aggravating the local electromigration, interface oxidation and thermal stress concentration of the heating electrode strip 1, which can easily cause local hot spots, voids or film fractures in the heating electrode strip 1).

[0045] In this specific embodiment, the thickness of both the first and second SiO2 thin film layers is 500 nm, the thickness of the Si substrate is 500 μm, the thickness of the adhesion layer is 10 nm, the thickness of the seed layer is 50 nm, and the thickness of the Ni metal heating layer is 1050 nm. In this specific embodiment, the adhesion layer is a Ti metal thin film layer, and the seed layer is a Ni metal thin film layer. The length of the two lead electrode strips 2 is 12240 μm, and the width is 400 μm.

[0046] The above describes a method for fabricating a MEMS microheater based on nickel metal heating, such as... Figure 1 As shown, it includes the following steps:

[0047] (a) The Si substrate was cleaned and dried with nitrogen gas. The first SiO2 thin film layer and the second SiO2 thin film layer were deposited on the back side and the front side of the Si substrate respectively by PECVD.

[0048] (b) A 10 nm thick Ti metal thin film and a 50 nm thick Ni metal thin film were sequentially deposited on the surface of the second SiO2 thin film using a magnetron sputtering process;

[0049] (c) Spin-coating AZ6130 positive photoresist onto the surface of the Ni metal thin film layer;

[0050] (d) Place the mask containing the metal heating unit pattern on the photoresist, using a positive mask, and then expose and develop it at an exposure dose of 200 mJ / cm².2 The development was performed for 28 seconds using a developer solution of TMAH and water at a volume ratio of 1:13.

[0051] (e) An electroplating process was used to electroplat a Ni metal heating layer on the surface of the exposed and developed Ni metal thin film. The electroplating solution consisted of 44 g / L NiCl2·6H2O, 35 ml / L boric acid, 1.5 g / L saccharin, and 0.4 g / L sodium dodecyl sulfate. The current density during electroplating was 5 mA / cm². 2 The electroplating time was 2 minutes and the electroplating rate was 500 nm / min.

[0052] (f) Clean the remaining photoresist;

[0053] (h) The Ni metal thin film layer and Ti metal thin film layer with non-electroplated Ni metal heating layer are etched by ion beam etching process. The energy of Ar ions is set to 500eV, the gas flux is set to 5sccm, and the ion beam etching rate is 20nm / min, thereby completing the fabrication of MEMS micro heater.

[0054] To verify the performance of the MEMS microheater described above, it was tested, and the test process is as follows:

[0055] Step S1: The fabricated microheater is powered on using a programmable constant current source, with current values ​​of 0.8A, 1.0A, 1.2A, 1.4A, 1.6A and 1.8A applied sequentially.

[0056] Step S2: Monitor the temperature change of the surface of the MEMS micro heater described in this invention under different currents and the infrared thermal imaging results in real time using thermocouples and infrared thermal imagers, and record the output voltage under each current setting.

[0057] like Figure 4 The figure shows the corresponding curves of temperature change on the surface of the MEMS micro heater described in this invention under different currents, as monitored in real time by thermocouples. Figure 4 It can be seen that as the input current gradually increases, the heating rate of the MEMS micro-heater accelerates significantly, and the maximum temperature increases substantially. Under the maximum driving current of 1.8A, the device temperature rises rapidly to approximately 600℃, demonstrating excellent high-temperature response capability. Simultaneously, the temperature drops rapidly after 60 seconds of power-on interruption, reflecting the device's good thermal response dynamics and heat dissipation performance. Furthermore, the temperature change curves under different current input conditions show consistent trends, further indicating that the device possesses good structural consistency and thermal stability.

[0058] like Figure 5The graph shows the trend of a stable increase in the output voltage of the MEMS micro-heater described in this invention with the energizing time under different current input conditions. This is because, under constant current drive, the resistance of the metal electrode gradually increases with increasing temperature, resulting in a corresponding increase in voltage. Figure 5 As can be seen, the voltage increases significantly with the increase of current and maintains a continuous and smooth change curve throughout the entire test range, without any sudden changes or failures, indicating that the device remains stable under different drive currents. At the same time, the relationship between current and voltage is close to linear, reflecting that the device has good electrothermal conversion characteristics and predictable electrical response. In addition, under a current drive condition of 1.8A, the voltage steadily rises to about 17V, further demonstrating that the device has reliable electrical stability and drive controllability.

[0059] like Figure 6 The image shown is an infrared imaging result of the surface of the MEMS microheater described in this invention under different current input conditions. The thermal field characteristics of the microheater under different driving current conditions were analyzed using an infrared thermal imager. Figure 6 It can be seen that under various test current levels, the heat of the micro heater is concentrated in the metal heating unit area, exhibiting a high heat concentration effect, and the overall thermal field shows a uniform symmetrical distribution pattern, which effectively proves the symmetry of the device and the rationality of the heat conduction path.

[0060] Therefore, the MEMS micro heater based on nickel metal heating proposed in this embodiment has good thermal energy concentration and heating response, which can meet the requirements of local temperature control and thermal activation. It is suitable for various application scenarios such as micro thermal drive devices, information protection systems, MEMS thermal triggering devices and information self-destruct modules.

[0061] Meanwhile, to further highlight and verify the performance of the MEMS microheater based on nickel metal heating described in this invention, the electroplated Ni metal heating layer was replaced with an Al metal heating layer, and it was found that its performance was poor, such as... Figure 7 As shown, under a 3A current drive, the device temperature only rises to 362.36℃ after 45s, indicating that its thermal energy is insufficient and its heating response is also poor.

[0062] Furthermore, to further verify the performance of the MEMS microheater described in this invention, it was applied to a thermal triggering functional unit. The specific test procedure is as follows:

[0063] Step S1: Integrate and fix the MEMS micro heater prepared in this invention with a porous silicon chip filled with energetic material on the experimental platform to ensure that the local area to be heated is in full contact with the energetic material;

[0064] Step S2: Apply a driving current to the MEMS micro heater prepared in this invention through a programmable constant current source to make it work in the set heating power state;

[0065] Step S3: Use a high-speed camera to acquire real-time images of the porous silicon energetic chip's response during the heating process, capturing the complete process of its thermal activation and energy release, such as... Figure 8 As shown.

[0066] Figure 8 The response images recorded by a high-speed camera demonstrate the entire process of the MEMS microheater fabricated in this invention igniting a porous silicon energetic chip. By applying a set driving current, the MEMS microheater can rapidly achieve localized high-temperature output and successfully ignite the energetic material, exhibiting obvious luminescence and violent combustion phenomena, accompanied by flame ejection and debris splashing. The entire reaction process is clear and stable, verifying that the microheater has the ability to drive a significant thermal reaction in energetic materials. This result indicates that the MEMS microheater described in this invention has good adaptability and output characteristics in terms of thermal driving and localized energy excitation, and can meet the application requirements of functional devices in scenarios such as thermal triggering, information protection, and microsystem self-destruction.

[0067] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A MEMS microheater based on nickel metal heating, characterized in that, The substrate includes a Si substrate, on the back side of which a first SiO2 thin film layer is deposited, and on the front side of which a second SiO2 thin film layer is deposited. A metal heating unit is deposited on the surface of the second SiO2 thin film layer. The metal heating unit includes multiple heating electrode strips (1) arranged side by side and two lead electrode strips (2) arranged front to back. The multiple heating electrode strips (1) are located between the two lead electrode strips (2), and both ends of each heating electrode strip (1) are connected to the two lead electrode strips (2) respectively. Each heating electrode strip (1) and lead electrode strip (2) consists of an adhesion layer, a seed layer and a Ni metal heating layer electroplated on the seed layer, which are deposited sequentially on the surface of the second SiO2 thin film layer. The width of the portion of the multiple heating electrode strips (1) corresponding to the local area to be heated is narrower than the width of the rest.

2. The MEMS microheater based on nickel metal heating according to claim 1, characterized in that, Each heating electrode strip (1) is dumbbell-shaped with wide ends and narrow middle in a top view.

3. A MEMS microheater based on nickel metal heating according to claim 2, characterized in that, Each heating electrode strip (1) has a width of 12 μm at both ends and 6 μm in the middle. The distance between the middle parts of two adjacent heating electrode strips (1) is 206 μm.

4. A MEMS microheater based on nickel metal heating according to claim 3, characterized in that, The thickness of both the first and second SiO2 thin film layers is 500 nm, the thickness of the Si substrate is 500 μm, the thickness of the adhesion layer is 10 nm, the thickness of the seed layer is 50 nm, and the thickness of the Ni metal heating layer is 1050 nm.

5. A MEMS microheater based on nickel metal heating according to claim 4, characterized in that, The adhesion layer is a Ti metal thin film layer.

6. A MEMS microheater based on nickel metal heating according to claim 5, characterized in that, The seed layer is a Ni metal thin film layer.

7. A MEMS microheater based on nickel metal heating according to claim 6, characterized in that, The length of the two lead electrode strips (2) is 12240μm and the width is 400μm.

8. A method for fabricating a MEMS microheater based on nickel metal heating as described in any one of claims 1 to 7, characterized in that, Includes the following steps: (a) The Si substrate is cleaned and dried with nitrogen gas, and a first SiO2 thin film layer and a second SiO2 thin film layer are deposited on the back side and the front side of the Si substrate, respectively. (b) An adhesion layer and a seed layer are sequentially deposited on the surface of the second SiO2 thin film using a magnetron sputtering process; (c) Spin-coating photoresist onto the surface of the seed layer; (d) Place the mask containing the metal heating unit pattern on the photoresist, and then expose and develop it; (e) An electroplating process is used to electroplat a Ni metal heating layer on the surface of the seed layer after exposure and development; (f) Clean the remaining photoresist; (h) The seed layer and adhesion layer with non-electroplated Ni metal heating layer are etched by etching process to complete the fabrication of MEMS micro heater.

9. The method for fabricating a MEMS microheater based on nickel metal heating according to claim 8, characterized in that, In step (e), the electroplating solution used in the electroplating process comprises 44 g / L NiCl2·6H2O, 35 ml / L boric acid, 1.5 g / L saccharin, and 0.4 g / L sodium dodecyl sulfate, and the current density during electroplating is 5 mA / cm². 2 The electroplating time was 2 minutes and the electroplating rate was 500 nm / min.

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