Method for improving stability of micro-bridge structure of micro-bolometer, micro-bridge structure of micro-bolometer, micro-bolometer and micro-bolometer chip
By adjusting the ratio of bridge leg height to width to 1:3, the bridge leg structure was optimized, resolving the contradiction between high response rate and mechanical stability in the microbridge structure of the microbolometer, and achieving a balance between high response rate and high mechanical stability.
Patent Information
- Application Number
- CN202511977913.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-03-13
AI Technical Summary
Existing microbridge structures for microbolometers struggle to balance high response rate and high mechanical stability. Reduced bridge leg dimensions lead to decreased mechanical strength, making them prone to failure issues such as breakage or collapse.
Adjust the ratio of bridge leg height to bridge leg width to be greater than 1:3, and make the bridge leg height consistent with the bridge deck height. This increases the bridge leg height to compensate for the loss of mechanical strength caused by the reduction in width, thereby optimizing the cross-sectional area and mechanical strength of the bridge legs.
It significantly reduces thermal conductivity, improves the response rate of microthermometers, enhances mechanical stability, avoids structural failure, and improves manufacturing yield and long-term service reliability.
Smart Images
Figure CN121655704A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of microelectromechanical systems (MEMS) technology, and in particular to a method for improving the stability of a microbridge structure of a microbolometer, as well as the microbridge structure of the microbolometer, the microbolometer, and the microbolometer chip. Background Technology
[0002] As the core sensing unit of uncooled infrared imaging systems, microbolometers commonly employ a suspended microbridge structure design. The bridge surface of this structure is equipped with a thermistor material, while the main body of the microbridge is supported by bridge legs, forming an electrical and mechanical connection with the underlying circuitry. The bridge legs perform two core functions: firstly, to provide stable mechanical support, ensuring the structural integrity of the microbridge; and secondly, to achieve efficient thermal isolation, creating the necessary conditions for the bridge surface to absorb infrared radiation and generate a significant temperature rise.
[0003] An ideal infrared detector needs to balance high responsivity (high sensitivity) and high reliability (mechanical stability). Responsivity is directly related to the detector's thermal insulation performance (characterized by thermal conductivity G). The lower the thermal conductivity, the greater the temperature rise of the bridge surface after absorbing the same amount of infrared radiation, and the higher the detector's responsivity. Among various techniques for reducing thermal conductivity, reducing the cross-sectional area of the bridge legs (i.e., reducing the width and / or height) is the most direct and effective method. However, at the same time, reducing the size of the bridge legs significantly weakens their mechanical strength, leading to a significant decrease in the damage resistance of the microbridge structure. Especially in the subsequent packaging, testing, and practical application stages, when exposed to external vibrations, airflow impacts, or thermal stress caused by temperature fluctuations, the microbridge structure is highly susceptible to failure problems such as bridge leg breakage, overall collapse, or interface adhesion.
[0004] Existing technologies face a dilemma in optimizing the thermal and mechanical performance of detectors: strengthening thermal isolation design to improve responsivity often comes at the cost of structural stability; conversely, maintaining the structural strength of the bridge legs to ensure mechanical stability makes it difficult to overcome the limitation of thermal conductivity on responsivity improvement. Therefore, there is an urgent need for a solution that can significantly reduce thermal conductivity while ensuring sufficient mechanical stability of the microbridge structure. Summary of the Invention
[0005] In view of this, the purpose of this application is to provide a method for improving the stability of the microbridge structure of a microbolometer, as well as the microbridge structure, microbolometer, and microbolometer chip, to solve the technical bottleneck of existing microbridge structures that are difficult to balance thermal isolation and mechanical performance stability.
[0006] To achieve the above-mentioned technical objectives, this application provides a method for improving the stability of a microbridge structure of a microthermometer. The method involves simultaneously adjusting the height and width of the bridge legs to make the ratio of the height to the width of the bridge legs greater than 1:3, thereby obtaining a stable microbridge structure for the microthermometer.
[0007] Furthermore, the height of the bridge legs is consistent with the height of the bridge deck.
[0008] Furthermore, the bridge leg includes a passivation layer, an electrode connection layer, and a support layer arranged sequentially from top to bottom; when adjusting the height of the bridge leg, the height of the bridge leg is increased by increasing the height of the bridge leg support layer and / or the passivation layer.
[0009] Furthermore, the width of the bridge legs is 0.25μm~0.35μm, and the height of the bridge legs is 0.1μm~0.3μm.
[0010] This application provides a microbridge structure for a microthermometer, including a readout circuit substrate, a support pillar, and a bridge surface;
[0011] The support pillar is vertically disposed on the upper surface of the readout circuit substrate; the bridge surface includes bridge legs, which are disposed above the readout circuit substrate and connected to the support pillar through the bridge legs; the bridge surface, support pillar, and readout circuit substrate together constitute an optical resonant cavity; wherein, the ratio of bridge leg height to bridge leg width is greater than 1:3.
[0012] Furthermore, the width of the bridge legs is 0.25μm~0.35μm, and the height is 0.1μm~0.3μm.
[0013] Furthermore, the width of the bridge legs is 0.25μm~0.35μm, and the height is 0.2μm~0.3μm.
[0014] Furthermore, the height of the bridge deck is consistent with the height of the bridge legs, both being 0.2μm~0.3μm.
[0015] This application provides a microradiometer, including a microradiometer microbridge structure or a microradiometer microbridge structure prepared by a method for improving the stability of the microbridge structure of the microradiometer.
[0016] This application provides a microthermometry chip, including a microthermometry microbridge structure or a microthermometry chip.
[0017] In summary, this application provides a method for improving the stability of a microbridge structure in a microthermometer. While maintaining a constant leg length, the height and width of the legs are simultaneously adjusted to achieve a height-to-width ratio greater than 1:3. By reducing the leg width and simultaneously increasing the leg height, this application reduces the cross-sectional area of the legs, effectively lowering the thermal conductivity of the microbridge structure and significantly improving the responsivity of the microthermometer. Simultaneously, the increased leg height compensates for the loss of mechanical strength due to the reduced width, ultimately achieving the dual technical goals of high responsivity and high mechanical stability in the microthermometer.
[0018] This application provides a microbridge structure for a microthermometer, including a readout circuit substrate, support pillars, and a bridge surface. The support pillars are vertically disposed on the upper surface of the readout circuit substrate, and the bridge surface is disposed above the readout circuit substrate and connected to the support pillars via bridge legs. The bridge surface, support pillars, and readout circuit substrate together form an optical resonant cavity. The height-to-width ratio of the bridge legs is greater than 1:3. This application effectively reduces heat conduction efficiency and improves the mechanical strength of the microbridge structure through synergistic optimization of height and width.
[0019] Compared with the prior art, the microbridge structure of the microthermometer provided in this application breaks through the technical bottleneck of thermal conductivity barrier and mechanical performance being difficult to balance. Moreover, the microbridge structure of the microthermometer is compatible with the existing MEMS process flow and does not require the introduction of extremely complex or expensive equipment. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a schematic diagram of a microbridge structure provided in Embodiment 1 of this application;
[0022] Figure 2 Characterization diagram of the curling of the microbridge structure provided in Example 2 during chip fabrication;
[0023] Figure labels: 1. Readout circuit substrate, 2. Support pillar, 3. Bridge surface, 4. Bridge leg, 5. Resonant cavity. Detailed Implementation
[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.
[0025] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship shown, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0026] Unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" 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 in this application based on the specific circumstances.
[0027] The raw materials used in this invention are not particularly restricted in their source; they can be purchased on the market or prepared using conventional methods known to those skilled in the art.
[0028] This application provides a method for improving the stability of a microbridge structure in a microthermometry. While keeping the leg length constant, the height and width of the legs of the microbridge structure are adjusted simultaneously so that the ratio of the leg height to the leg width is greater than 1:3, thereby obtaining a stable microbridge structure for the microthermometry.
[0029] It should be noted that this application directly reduces heat conduction by decreasing the cross-sectional area of the bridge legs through narrowing the leg width; simultaneously increasing the leg height significantly improves the bending section modulus, effectively enhancing the structure's resistance to multi-directional bending moments and shear forces. Furthermore, the tall, narrow leg structure possesses a higher natural vibration frequency, effectively avoiding resonance coupling with low-frequency airflow disturbances in the environment and significantly reducing the risk of structural fatigue damage. In addition, this structure effectively buffers mechanical and thermal stresses generated during post-packaging processes and actual service, greatly suppressing failure modes such as collapse and fracture of the microbridge structure, thereby significantly improving product manufacturing yield and long-term service reliability. The microbridge structure can also optimize compatibility with existing microelectromechanical system (MEMS) standard processes through optimized surface micromachining, eliminating the need for extremely complex or high-cost specialized equipment, thus laying the technological foundation for large-scale mass production applications.
[0030] In some embodiments, the bridge leg includes a passivation layer, an electrode connection layer, and a support layer arranged sequentially from top to bottom; when adjusting the height of the bridge leg, the height of the electrode connection layer remains unchanged, and the height of the bridge leg is increased by increasing the height of the bridge leg support layer and / or the passivation layer.
[0031] In some embodiments, the width of the bridge leg is 0.25 μm to 0.35 μm, the height of the bridge leg is 0.1 μm to 0.3 μm, and the cross-sectional area of the bridge leg is 0.05 μm². 2 ~0.075μm 2 .
[0032] In some preferred embodiments, the width of the bridge leg is 0.25 μm to 0.35 μm, the height of the bridge leg is 0.2 μm to 0.3 μm, and the cross-sectional area of the bridge leg is 0.05 μm². 2 ~0.075μm 2 .
[0033] In some preferred embodiments, the height of the bridge legs is the same as the height of the bridge deck, both being 0.2μm~0.3μm.
[0034] In some preferred embodiments, the ratio of the bridge leg height to its width is 3:5 to 1.
[0035] This application provides a microbridge structure for a microthermometer, including a readout circuit substrate, a support pillar, and a bridge surface;
[0036] The support pillars are vertically positioned on the upper surface of the readout circuit substrate;
[0037] The bridge deck includes bridge legs, which are positioned above the readout circuit substrate and connected to the support pillars via the bridge legs. The bridge deck, support pillars, and readout circuit substrate together constitute an optical resonant cavity. The ratio of the bridge leg height to the bridge leg width is greater than 1:3.
[0038] In some embodiments, the bridge legs are centrally symmetrically distributed, with one end of the bridge leg fixedly connected to the bridge deck and the other end snapped into a support column.
[0039] In some preferred embodiments, the ratio of the bridge leg height to the bridge leg width is 3:5 to 1.
[0040] In some embodiments, the width of the bridge leg is 0.25μm to 0.35μm, and the height is 0.1μm to 0.3μm.
[0041] In some preferred embodiments, the width of the bridge leg is 0.25μm to 0.35μm, and the height of the bridge leg is 0.2μm to 0.3μm.
[0042] In some preferred embodiments, the height of the bridge deck is the same as the height of the bridge legs, both being 0.2μm~0.3μm.
[0043] This application provides a microradiometer, including a microradiometer microbridge structure or a microradiometer microbridge structure prepared by a method for improving the stability of the microbridge structure of the microradiometer.
[0044] This application provides a microthermometry chip, including a microthermometry microbridge structure or a microthermometry chip.
[0045] The applicant further provides the following specific embodiments to describe the present invention. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.
[0046] Example 1
[0047] See Figure 1 This embodiment provides a microbridge structure for a microthermometer. The microbridge structure adopts a single-layer structure design and specifically includes a readout circuit substrate, a support pillar, and a bridge surface.
[0048] The readout circuit substrate serves as a supporting base for the microbridge structure, providing a mounting reference for subsequent components.
[0049] The support pillars are vertically positioned on the upper surface of the readout circuit substrate to achieve a stable connection between the bridge legs and the substrate.
[0050] The bridge surface is located above the readout circuit substrate and together with the support pillar and the readout circuit substrate, it forms an optical resonant cavity. The bridge surface includes, from bottom to top, a support layer, a thermistor layer, a passivation layer, an electrode connection layer, and a passivation layer.
[0051] The bridge deck also includes two centrally symmetrically distributed bridge legs. From bottom to top, each bridge leg consists of a support layer, an electrode connection layer, and a passivation layer. One end of each bridge leg is fixedly connected to the bridge deck, while the other end is snapped into a support column, providing mechanical support for the bridge deck and also providing an electrical connection channel for the heat-sensitive layer of the bridge deck.
[0052] This embodiment provides a method for improving the stability of a microbridge structure in a microthermometer. While keeping the leg length constant, the leg width (W) and leg height (H) are adjusted simultaneously. In this embodiment, the parameters of the leg and the bridge surface are shown in Table 1.
[0053] Because the maximum stress of the microbridge structure is concentrated at the bend of the bridge leg under its own weight, the magnitude of the stress at the bend directly determines the mechanical stability of the microbridge structure. The smaller the stress on the microbridge structure, the higher its mechanical stability. To clarify the influence of different bridge leg parameters on mechanical performance, mechanical performance tests were conducted on the bridge legs in this embodiment. The test data are detailed in Table 1.
[0054] Microbolometer chip fabrication: The chip fabricated using the parameters of Example 7 exhibits superior bending resistance, while the chip fabricated using the parameters of Example 2 is more prone to warping during fabrication. See [link to example]. Figure 2 The neatly arranged patterns showed misalignment between rows and columns. Therefore, during chip fabrication, maintaining the same height between the bridge legs and the bridge surface is more beneficial for fabricating the microbolometer chip.
[0055] Examples 2 to 9
[0056] Examples 2 to 9 provide a method for improving the stability of a microbridge structure in a microthermometer. The difference between these methods and Example 1 is that the height and width of the bridge legs, the length, height, and width of the bridge deck are different, as shown in Table 1.
[0057] Table 1. Maximum mechanical stress on the microbridge structure of the microthermometry under different parameters
[0058]
[0059] Based on the data in Table 1, the following conclusions can be drawn: The data from Examples 1 and 2 show that, with other parameters remaining constant, reducing the width of the bridge legs leads to an increase in the stress on the microbridge structure; the data from Examples 1 and 6 show that, with a decrease in the width of the bridge legs and an increase in the weight of the bridge deck, the stress on the microbridge structure further increases; the data from Examples 2 and 6 show that, with other parameters remaining constant, an increase in the weight of the bridge deck increases the stress on the microbridge structure; the data from Examples 3-5 and Examples 6-8 show that, with other parameters remaining constant, an increase in the height of the bridge legs decreases the stress on the microbridge structure.
[0060] In summary, a narrower bridge leg width is not necessarily better. Excessively narrow legs are insufficient to support the bridge deck and are prone to collapse under external forces. Therefore, while considering the requirements of low thermal conductivity, high responsibility, and structural stability of the microbridge structure, the bridge legs need to be heightened. Specifically, this can be achieved by thickening the support layer at the bottom of the bridge leg and the passivation layer at the top, while keeping the height of the electrode connection layer unchanged.
[0061] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although this application has been described in detail with reference to examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for improving the stability of a microbridge structure in a microthermometer, characterized in that, The height and width of the bridge legs of the microbridge structure are adjusted synchronously so that the ratio of the bridge leg height to the bridge leg width is greater than 1:3, thereby obtaining a stable micro-bridge structure for the microthermometer.
2. The method for improving the stability of the microbridge structure of a microthermometer according to claim 1, characterized in that, The height of the bridge legs is the same as the height of the bridge deck.
3. The method for improving the stability of the microbridge structure of a microthermometer according to claim 1, characterized in that, The bridge leg includes a passivation layer, an electrode connection layer, and a support layer arranged sequentially from top to bottom; When adjusting the height of the bridge legs, the height of the bridge legs is increased by increasing the height of the bridge leg support layer and / or passivation layer.
4. The method for improving the stability of the microbridge structure of a microthermometer according to claim 1, characterized in that, The width of the bridge leg is 0.25μm to 0.35μm, and the height of the bridge leg is 0.1μm to 0.3μm.
5. A microbridge structure for a microthermometer, characterized in that, This includes the readout circuit substrate, support pillars, and bridge surface; The support pillar is vertically disposed on the upper surface of the readout circuit substrate; The bridge deck includes bridge legs, which are disposed above the readout circuit substrate and connected to the support column via the bridge legs; the bridge deck, the support column, and the readout circuit substrate together constitute an optical resonant cavity; wherein the ratio of the bridge leg height to the bridge leg width is greater than 1:
3.
6. The microbridge structure of the microthermometer according to claim 5, characterized in that, The width of the bridge legs is 0.25μm~0.35μm, and the height is 0.1μm~0.3μm.
7. The microbridge structure of the microthermometer according to claim 6, characterized in that, The width of the bridge legs is 0.25μm~0.35μm, and the height is 0.2μm~0.3μm.
8. The microbridge structure of the microthermometer according to claim 7, characterized in that, The height of the bridge deck is the same as the height of the bridge legs, both being 0.2μm~0.3μm.
9. A microradiometer, characterized in that, This includes a microthermometry microbridge structure obtained by the method for improving the stability of a microthermometry microbridge structure as described in any one of claims 1 to 4, or a microthermometry microbridge structure as described in any one of claims 5 to 8.
10. A microthermometry chip, characterized in that, This includes a microthermometry microbridge structure obtained by the method for improving the stability of a microthermometry microbridge structure as described in any one of claims 1 to 4, or a microthermometry microbridge structure as described in any one of claims 5 to 8, or a microthermometry as described in claim 9.