MEMS heater based on flexible circuit board and preparation method thereof

Abstract

The invention discloses an MEMS heater based on a flexible circuit board and a preparation method thereof, the MEMS heater based on the flexible circuit board comprises the flexible circuit board, and an application-specific integrated circuit chip and a heating plate which are arranged on the flexible circuit board, the heating plate comprises a plurality of MEMS heaters, and the application-specific integrated circuit chip and the heating plate are both connected with the flexible circuit board; the preparation method comprises the following steps: preparing the heating plate, the flexible circuit board and the special integrated circuit chip; and mounting the special integrated circuit chip and the heating plate patch on the flexible circuit board. According to the embodiment of the invention, the application scene of the MEMS heater is expanded, large-scale production is facilitated, and the MEMS heater can be widely applied to the technical field of microelectronics.

Description

Technical Field

[0001] The invention relates to the field of microelectronic technology, and in particular to a MEMS heater based on a flexible circuit board and a preparation method thereof. Background Art

[0002] Micro heaters based on microelectromechanical systems (MEMS) have the advantages of small size, fast response speed, low power consumption, etc., and have great potential in gas sensing, pressure sensing, humidity sensing, flow measurement, infrared light source, micro-area heating and other MEMS applications. Existing MEMS micro heaters usually use hard printed circuit boards, and their application scenarios are limited. Summary of the invention

[0003] In view of this, in order to solve one of the above problems, an object of an embodiment of the present invention is to provide a MEMS heater based on a flexible circuit board and a preparation method thereof, so as to expand the application scenarios of the MEMS heater.

[0004] On the one hand, an embodiment of the present invention provides a MEMS heater based on a flexible circuit board, including a flexible circuit board and a dedicated integrated circuit chip and a heating plate arranged on the flexible circuit board, the heating plate containing a plurality of MEMS heaters, and the dedicated integrated circuit chip and the heating plate are both connected to the flexible circuit board.

[0005] Optionally, the heating plate further comprises a substrate, and a positive electrode, a negative electrode and a plurality of wires arranged on the substrate, and each of the MEMS heaters is respectively connected to the positive electrode and the negative electrode via wires.

[0006] Optionally, the MEMS heater includes a substrate layer, a transition layer, a device layer, a protective layer, a heating electrode and a heating winding structure, wherein the heating electrode and the heating winding structure are arranged on the surface of the device layer, and the protective layer protects the heating electrode and the heating winding structure.

[0007] Optionally, the heating winding structure includes a Hilbert-third-order curve winding structure.

[0008] Optionally, the material of the substrate layer includes silicon.

[0009] Optionally, the material of the transition layer includes silicon dioxide or silicon nitride.

[0010] Optionally, the material of the device layer includes silicon or silicon nitride.

[0011] Optionally, the MEMS heater further includes an anti-oxidation layer, and the anti-oxidation layer is arranged on a preset surface of the heating electrode.

[0012] On the other hand, an embodiment of the present invention provides a method for preparing a MEMS heater based on a flexible circuit board, comprising:

[0013] Prepare a heating plate, a flexible circuit board, and a dedicated integrated circuit chip; the heating plate includes a plurality of MEMS heaters;

[0014] The dedicated integrated circuit chip and the heating plate patch are mounted on the flexible circuit board.

[0015] Optionally, the preparation method of the MEMS heater is as follows:

[0016] Providing a substrate layer, and preparing a transition layer and a device layer on the substrate layer;

[0017] Photolithography is performed on the device layer to pattern the heating electrode and the heating winding structure, and a conductive layer is prepared on the device layer to form the heating electrode and the heating winding structure;

[0018] Preparing a protective layer on the surface of the device layer, the heating electrode and the heating winding structure, and opening a window at a preset position of the heating electrode;

[0019] A protective layer, a device layer, a transition layer and a substrate layer are etched at a preset position between the heating electrode and the heating winding structure to form a suspended heating platform.

[0020] The implementation of the embodiments of the present invention includes the following beneficial effects: the MEMS heater based on the flexible circuit board in the embodiment includes a flexible circuit board and a dedicated integrated circuit chip and a heating plate arranged on the flexible circuit board, the heating plate includes a plurality of MEMS heaters, the dedicated integrated circuit chip and the heating plate are both connected to the flexible circuit board, the dedicated integrated circuit chip controls the heating of the MEMS heater through the flexible circuit board, and the MEMS micro heater is combined with the flexible circuit board, which can be applied to flexible smart wearable heating devices, micro-area heating applications, etc., expanding the application scenarios of the MEMS micro heater. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural schematic diagram of a MEMS heater based on a flexible circuit board provided by an embodiment of the present invention;

[0022] Figure 2 is a structural schematic diagram of a heating plate provided by an embodiment of the present invention;

[0023] Figure 3 is a schematic structural diagram of a single MEMS heater provided by an embodiment of the present invention;

[0024] Figure 4It is a temperature schematic diagram of a MEMS heater based on a flexible circuit board under different voltages provided by an embodiment of the present invention;

[0025] Figure 5 It is a schematic flow chart of the steps of a method for preparing a MEMS heater based on a flexible circuit board provided by an embodiment of the present invention;

[0026] Figure 6 It is a flow chart of another method for preparing a MEMS heater based on a flexible circuit board provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0028] like Figure 1 As shown, Figure 1 (a) shows a top view of a MEMS heater based on a flexible circuit board. Figure 1 (b) shows a side view of a MEMS heater based on a flexible circuit board. An embodiment of the present invention provides a MEMS heater based on a flexible circuit board, comprising a flexible circuit board (1) and a dedicated integrated circuit chip (2) and a heating plate (3) arranged on the flexible circuit board (1), wherein the heating plate (3) comprises a plurality of MEMS heaters, and the dedicated integrated circuit chip (2) and the heating plate (3) are both connected to the flexible circuit board (1).

[0029] Flexible printed circuit board, referred to as FPC, is a circuit board made of a flexible substrate, which has the advantages of being bendable, light weight and thin.

[0030] The dedicated integrated circuit chip stores a control program to control the MEMS heater. The flexible circuit board includes a plurality of wire links. The dedicated integrated circuit chip is connected to the MEMS heater through the wire links of the flexible circuit board.

[0031] The implementation of the embodiments of the present invention includes the following beneficial effects: the MEMS heater based on the flexible circuit board in the embodiment includes a flexible circuit board and a dedicated integrated circuit chip and a heating plate arranged on the flexible circuit board, the heating plate includes a plurality of MEMS heaters, the dedicated integrated circuit chip and the heating plate are both connected to the flexible circuit board, the dedicated integrated circuit chip controls the heating of the MEMS heater through the flexible circuit board, and the MEMS micro heater is combined with the flexible circuit board, which can be applied to flexible smart wearable heating devices, micro-area heating applications, etc., expanding the application scenarios of the MEMS micro heater.

[0032] Optionally, see Figure 2 The heating plate (3) further comprises a substrate (31) and a positive electrode (33), a negative electrode (34) and a plurality of wires (35 / 36) arranged on the substrate (31), and each MEMS heater (32) is connected to the positive electrode (33) and the negative electrode (34) respectively via the wires (35 / 36).

[0033] The MEMS heaters are arranged in an array, and the specific arrangement is determined according to the actual application, and this embodiment does not make any specific restrictions, such as a square array or a rectangular array. The number of MEMS micro heaters varies according to the heating area.

[0034] In a specific embodiment, 3×3 MEMS microheaters (32) are arranged on a substrate (31), and there are positive electrodes (33) and negative electrodes (34) on the upper and lower sides of the substrate (31). The positive electrodes (33) and the negative electrodes (34) are connected to each MEMS microheater (32) through wires (35 / 36), respectively. After voltage is applied, each MEMS microheater (32) can generate the same temperature. In another embodiment, the positive electrode among the positive electrodes (33) and the negative electrodes (34) is regarded as an array set of positive electrodes corresponding to each heater, and the wires 35 and 36 are regarded as buses. Each MEMS microheater (32) can be individually applied with voltage, and different voltages can be applied to each MEMS microheater (32) to obtain different temperatures in different areas, which can be applied to micro-area heating applications that require different regional temperatures. At the same time, the MEMS microheater (32) has a fast response speed, and the temperature can be changed by quickly changing the voltage.

[0035] Optionally, see Figure 3 , Figure 3 (a) shows the top view of the MEMS heater. Figure 3 (b) shows a cross-sectional view of the MEMS heater, which includes a substrate layer (326), a transition layer (325), a device layer (324), a protective layer (323), a heating electrode (321) and a heating winding structure (322). The heating electrode (321) and the heating winding structure (322) are arranged on the surface of the device layer (324), and the protective layer (323) protects the heating electrode (321) and the heating winding structure (322).

[0036] It should be noted that the thickness and material of each layer in the MEMS heater are determined according to the actual application, and this embodiment does not impose any specific restrictions. The position of the heating winding structure (322) is determined according to the actual application, and this embodiment does not impose any specific restrictions. For example, the heating winding structure (322) is located at the center of the MEMS heater structure.

[0037] The MEMS microheater has a suspended structure. The suspended heating platform is the main heating temperature zone with the highest temperature. The heating platform is slightly larger than the heater winding structure. The larger the area of ​​the heating winding structure and the suspended heating platform, the lower the temperature will be.

[0038] Optionally, the heating winding structure includes a Hilbert-third-order curve winding structure.

[0039] It should be noted that the heating winding structure is determined according to actual application and is not specifically limited in this embodiment.

[0040] Optionally, the material of the substrate layer includes silicon.

[0041] Optionally, the material of the transition layer includes silicon dioxide or silicon nitride.

[0042] Optionally, the material of the device layer includes silicon or silicon nitride.

[0043] The substrate structure of the MEMS microheater is preferably a silicon-on-insulator structure, and the silicon dioxide buried layer or the upper silicon layer may also be replaced by an insulating material such as silicon nitride.

[0044] The material of the protection layer includes but is not limited to insulating materials such as silicon dioxide or silicon nitride.

[0045] Optionally, the MEMS heater further includes an anti-oxidation layer, and the anti-oxidation layer is disposed on a preset surface of the heating electrode.

[0046] The electrode material and the heating winding structure material of the MEMS microheater are preferably Ag material, and other metal materials can be replaced according to the required temperature, including but not limited to Au, Ag, Al, W, Ti, Cr, Pt, Cu, etc. For anti-oxidation metals, there is no need to add an extra anti-oxidation layer.

[0047] In a specific embodiment, the material of the heater electrode (321) and the heating winding structure (322) of the heater is 200nm thick Ag. The line width of the heating winding structure (322) is 20μm, the winding pitch is 10μm, and it is located at the center of the MEMS heater structure. The structure of the MEMS heater includes a 300μm thick silicon substrate layer (326), a 2μm thick silicon dioxide transition layer (325), a 5μm thick silicon device layer (324), and a 2μm thick protective silicon dioxide layer (323). The electrode (321) and the heating winding structure (322) are located on the silicon device layer (324) and are wrapped and protected by the silicon dioxide layer (323). The substrate area of ​​the MEMS microheater is 1200μm×1200μm, the heating winding structure (322) is located on a suspended heating platform, the heating platform area is 270μm×270μm, the heating platform is supported by cantilever beams on the left and right sides, the cantilever beams are 100μm long and 50μm wide, and the electrodes (321) are located on the left and right sides, with an area of ​​300μm×800μm. The MEMS microheater adopts a suspended structure to increase the temperature of the heater. At the same time, the thickness of the heating platform is thinner, and the narrower or longer the cantilever beam is, the higher the temperature of the heater can be. Considering the structural stability, it is necessary to design appropriate structural parameters and sacrifice certain heating temperature performance.

[0048] The FPC-based MEMS microheater proposed in the embodiment of the present invention adopts a new winding structure, which increases the temperature of the heater and reduces the size of the heater. Through array arrangement, the voltage on each heater can be changed to change different temperatures in a small area, so that the target can have different temperatures in different areas, and the target can exhibit special performance in micro-area heating applications. At the same time, the same voltage can be applied to all heaters to maintain the same temperature in different small areas. Since the MEMS microheater has a fast response speed, the temperature can be changed by quickly changing the voltage, and combined with the flexible circuit board FPC, the application scenarios of the MEMS microheater are expanded.

[0049] See also Figure 4 , Figure 4 The maximum temperature and average temperature of the MEMS microheater under different voltages are shown. The results are obtained by software simulation, and the structural parameters adopt the above-mentioned related parameters. Under voltages of 0.5V, 1V, 1.5V, 2V, 2.5V and 3V, the maximum temperature and average temperature generated by the MEMS microheater are 317.21K, 369.42K, 455.97K, 576.85K, 730.94K, 916.44K and 316.11K, 365.01K, 446.08K, 559.31K, 703.65K, 877.40K respectively. Figure 4The designed MEMS microheater has excellent heating temperature, low power consumption, and good temperature uniformity. In addition, the MEMS microheater also has good response and heating rate, which can respond within 1-2 seconds and reach the target temperature within 3-5 seconds.

[0050] See also Figure 5 The embodiment of the present invention provides a method for preparing a MEMS heater based on a flexible circuit board, comprising:

[0051] S100, preparing a heating plate, a flexible circuit board, and a dedicated integrated circuit chip; the heating plate includes a plurality of MEMS heaters;

[0052] S200, installing the dedicated integrated circuit chip and the heating plate patch on the flexible circuit board.

[0053] First, the heating plate, the flexible circuit board, and the dedicated integrated circuit chip are prepared according to their respective processes, and then the dedicated integrated circuit chip and the heating plate patch are installed on the flexible circuit board according to the preset positions.

[0054] In a specific embodiment, the MEMS micro heater is mounted in an array on a substrate, which can be a hardware board and a flexible board, and the assembled heating plate and flexible circuit board patch are mounted on the flexible circuit board. In some applications, such as wearable devices, a special structure can be designed at the edge so that the two ends of the heater are connected to form a ring structure as another implementation method.

[0055] Optionally, the preparation method of the MEMS heater is as follows:

[0056] S101, providing a substrate layer, and preparing a transition layer and a device layer on the substrate layer;

[0057] S102, photolithography on the device layer to pattern the heating electrode and the heating winding structure, and preparing a conductive layer on the device layer to form the heating electrode and the heating winding structure;

[0058] S103, preparing a protective layer on the surface of the device layer, the heating electrode and the heating winding structure, and opening a window at a preset position of the heating electrode;

[0059] S104, etching the protection layer, the device layer, the transition layer and the substrate layer at a preset position between the heating electrode and the heating winding structure to form a suspended heating platform.

[0060] See also Figure 6In a specific embodiment, the preparation method of the MEMS heater is as follows: (a) preparing an SOI silicon wafer that meets the parameter requirements, including a 300 μm thick silicon substrate layer (326), a 2 μm thick silicon dioxide layer (325), and a 5 μm thick silicon device layer (324), and completing pre-processes such as cleaning; in addition, a 2 μm thick silicon dioxide layer and a 5 μm thick silicon device layer can be grown on the 300 μm thick silicon wafer by plasma enhanced chemical vapor deposition (PECVD) and epitaxial growth; (b) performing photolithography on the SOI silicon wafer to pattern the electrode (321) and the heater structure (322), and then sputtering and depositing Deposit a 10nm thick adhesion layer metal, which can be Ti or Cr, and then deposit a 200nm thick Ag thin film layer, which is then peeled off to leave an electrode (321) and a heater structure (322); (c) deposit a 2μm thick silicon dioxide protective layer (323) by PECVD, then open a window at the electrode by photolithography and etching, and deposit a 10nm thick anti-oxidation metal, including Ti, Pt, etc.; (d) etch the 2μm thick silicon dioxide protective layer, 5μm thick silicon device layer, and 2μm thick silicon dioxide layer in sequence; (e) perform back etching of a 300μm thick silicon substrate layer to obtain a corresponding suspended heating platform.

[0061] The preparation process of MEMS heaters is compatible with semiconductor processes, the process is mature, the cost is low, and it is easy to prepare on a large scale.

[0062] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A MEMS heater based on a flexible circuit board, characterized in that: It comprises a flexible circuit board, a dedicated integrated circuit chip and a heating plate arranged on the flexible circuit board, the heating plate comprises a plurality of MEMS heaters, and the dedicated integrated circuit chip and the heating plate are both connected to the flexible circuit board.

2. The heater according to claim 1, characterized in that The heating plate further comprises a substrate, and a positive electrode, a negative electrode and a plurality of wires arranged on the substrate, and each of the MEMS heaters is respectively connected to the positive electrode and the negative electrode through a wire.

3. The heater according to claim 2, characterized in that The MEMS heater comprises a substrate layer, a transition layer, a device layer, a protective layer, a heating electrode and a heating winding structure. The heating electrode and the heating winding structure are arranged on the surface of the device layer, and the protective layer protects the heating electrode and the heating winding structure.

4. The heater according to claim 3, characterized in that The heating winding structure includes a Hilbert-third-order curve winding structure.

5. The heater according to claim 3, characterized in that The material of the substrate layer includes silicon.

6. The heater according to claim 3, characterized in that The material of the transition layer includes silicon dioxide or silicon nitride.

7. The heater according to claim 3, characterized in that The material of the device layer includes silicon or silicon nitride.

8. The heater according to claim 3, characterized in that The MEMS heater further includes an anti-oxidation layer, and the anti-oxidation layer is disposed on a predetermined surface of the heating electrode.

9. A method for preparing a MEMS heater based on a flexible circuit board, characterized in that: include: Prepare a heating plate, a flexible circuit board, and a dedicated integrated circuit chip; the heating plate includes a plurality of MEMS heaters; The dedicated integrated circuit chip and the heating plate patch are mounted on the flexible circuit board.

10. The preparation method according to claim 9, characterized in that: The preparation method of the MEMS heater is as follows: Providing a substrate layer, and preparing a transition layer and a device layer on the substrate layer; Photolithography is performed on the device layer to pattern the heating electrode and the heating winding structure, and a conductive layer is prepared on the device layer to form the heating electrode and the heating winding structure; Preparing a protective layer on the surface of the device layer, the heating electrode and the heating winding structure, and opening a window at a preset position of the heating electrode; A protective layer, a device layer, a transition layer and a substrate layer are etched at a preset position between the heating electrode and the heating winding structure to form a suspended heating platform.

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