Low-power-consumption MEMS constant-temperature crystal oscillator based on diamond heat conduction layer

Abstract

The invention discloses a low-power-consumption MEMS constant-temperature crystal oscillator based on a diamond heat conduction layer, and relates to the crossing field of a micro electro mechanical system and a frequency control device. Comprising an MEMS resonator containing a diamond heat conduction layer and a heating element, the MEMS resonator containing the diamond heat conduction layer comprises a resonator chip and the diamond heat conduction layer, and the resonator chip and the diamond heat conduction layer are metallurgically bonded through a wafer-level bonding process. The area of the diamond heat conduction layer is matched with the heating area of the resonator chip; and the heating element is arranged in an area close to the diamond heat conduction layer and is used for outputting heat required by temperature rise of the resonator chip. The constant-temperature crystal oscillator is used for solving the technical bottlenecks that an existing constant-temperature crystal oscillator based on an MEMS resonator is too long in preheating time, high in power consumption, limited in frequency stability due to temperature gradient and the like.

Description

Technical Field

[0001] This application relates to the cross-technical field of microelectromechanical systems (MEMS) and frequency control devices, and in particular to a low-power MEMS temperature-controlled crystal oscillator based on a diamond thermal conductive layer. Background Technology

[0002] Oven-controlled crystal oscillators (OCXOs) are high-precision frequency sources that rely on placing the resonator in a constant temperature environment to counteract the effects of ambient temperature fluctuations on the resonant frequency. They are core components in fields such as communications, test and measurement, and aerospace. With the miniaturization, portability, and low power consumption of electronic devices, MEMS-based oven-controlled crystal oscillators (MEMS-CCXOs) are gradually replacing traditional quartz oven-controlled crystal oscillators due to their advantages such as small size, light weight, and mass production capabilities. However, existing MEMS-CCXOs and quartz OCXOs still face the following key technological bottlenecks:

[0003] First, the preheating time is too long, failing to meet the requirements for immediate startup. Traditional temperature-controlled crystal oscillators rely on low thermal conductivity materials such as silicon and ceramics to transfer heat between the resonator and the heating element, resulting in significantly high thermal resistance. This makes it difficult for heat to quickly penetrate to the core resonant region of the resonator. In existing technologies, the preheating time of MEMS-type temperature-controlled crystal oscillators is typically long, while the preheating time of quartz-based temperature-controlled crystal oscillators is even longer, making it difficult to meet the requirements of scenarios such as 5G communication base stations and portable emergency testing equipment that require immediate response to startup.

[0004] Secondly, power consumption is high. During the preheating stage, the heater needs to output a high peak power to overcome high thermal resistance and achieve rapid temperature rise. During the steady-state isothermal stage, due to large heat loss and lag in temperature compensation response, a certain amount of maintenance power needs to be continuously output. For battery-powered portable devices (such as handheld spectrum analyzers and field monitoring terminals), this power consumption level will significantly shorten the device's battery life, severely restricting the expansion of its practical application scenarios.

[0005] Third, temperature gradients limit frequency stability. In traditional structures, there is a significant temperature gradient (up to 5-10℃ / mm) inside the resonator chip, which causes thermal stress deformation, making it difficult for the short-term stability of the resonant frequency to meet the frequency accuracy requirements of high-end communication equipment.

[0006] In the prior art, in order to improve heat conduction efficiency, researchers have tried to use copper film, aluminum nitride (AlN) film and other materials as heat conduction media (such as the structure disclosed in CN108736152A). However, the thermal conductivity of such materials is still limited and cannot fundamentally reduce thermal resistance. Another approach is to increase the heating power to shorten the preheating time (such as CN110247879B), but this approach will further aggravate the power consumption problem. Summary of the Invention

[0007] The purpose of this application is to provide a low-power MEMS thermostatic crystal oscillator based on a diamond thermal conductive layer, thereby solving the aforementioned key technical bottlenecks of existing thermostatic crystal oscillators based on MEMS resonators.

[0008] To achieve the above objectives, this application adopts the following technical solution:

[0009] This application provides a low-power MEMS temperature-controlled crystal oscillator based on a diamond thermally conductive layer, comprising a MEMS resonator containing a diamond thermally conductive layer and a heating element, wherein:

[0010] The MEMS resonator containing a diamond thermal conductive layer includes a resonator chip and a diamond thermal conductive layer. The resonator chip and the diamond thermal conductive layer are metallurgically bonded by a wafer-level bonding process. The area of ​​the diamond thermal conductive layer is matched with the heat-generating area of ​​the resonator chip.

[0011] The heating element is positioned in the region adjacent to the diamond thermally conductive layer and is used to output the heat required to heat up the resonator chip.

[0012] Optionally, the heating area of ​​the heating element is matched with the area of ​​the diamond thermally conductive layer.

[0013] Optionally, the diamond thermal conductive layer is prepared using a chemical vapor deposition process and is a single-crystal diamond thin film.

[0014] Optionally, the heating element employs an integrated power transistor for heating.

[0015] Optionally, it also includes a thermistor and a temperature control module, wherein:

[0016] The sensing end of the thermistor is connected to the diamond thermal conductive layer to collect the real-time temperature of the resonator chip and feed it back to the temperature control module.

[0017] The temperature control module is used to dynamically compare the real-time temperature with the preset temperature, calculate the temperature difference and the rate of change, and output a drive signal to dynamically adjust the power of the heating element, so as to achieve adaptive adjustment of rapid heating and precise heat preservation.

[0018] Optionally, the sensing end of the thermistor is connected to the diamond thermally conductive layer via a highly thermally conductive adhesive.

[0019] Optionally, a constant temperature bath is also included, wherein:

[0020] The MEMS resonator containing a diamond thermal conductive layer, heating element, thermistor, and temperature control module are compactly placed in a constant temperature bath.

[0021] Optionally, the constant temperature bath adopts a lightweight composite heat-insulating cavity structure.

[0022] Optionally, the cavity wall of the constant temperature bath adopts a double-layer collaborative design, with the inner layer focusing on efficient heat conduction blocking and the outer layer taking into account both structural compactness and support reliability.

[0023] Optionally, the core resonant region of the MEMS resonator containing the diamond thermal conductive layer is fabricated using a refined process to ensure stable operating frequency characteristics.

[0024] Based on the above technical solution, this application can achieve the following technical effects:

[0025] By introducing a high thermal conductivity diamond material layer at the bottom of the MEMS resonator structure, an efficient heat conduction path is constructed. This significantly shortens the preheating cycle of the isothermal MEMS resonator, fully meeting the requirements of instantaneous response scenarios with stringent start-up speed requirements. Simultaneously, it significantly reduces system energy consumption, effectively controlling both instantaneous power consumption during preheating and maintenance power consumption during steady-state operation, making it suitable for low-power applications. By optimizing the internal temperature distribution of the resonator chip and reducing the temperature gradient, the impact of thermal stress is effectively reduced, thereby improving short-term frequency stability. Furthermore, this solution fully retains the inherent miniaturization advantages of MEMS devices and is highly compatible with existing wafer-level mass production processes, requiring no additional production line modifications. This helps reduce industrialization costs and achieves synergistic optimization of thermal conductivity, energy consumption control, size integration, and mass production feasibility. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the system principle of a low-power MEMS thermostatic crystal oscillator based on a diamond thermal conductive layer, provided in one embodiment of this application.

[0027] Figure 2 This is a schematic diagram of the manufacturing process of a MEMS resonator chip containing a diamond thermal conductive layer provided in an embodiment of this application. Detailed Implementation

[0028] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present application will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not to scale, and are only used to facilitate and clarify the illustration of the embodiments of the present application.

[0029] It should be noted that, in order to clearly illustrate the content of this application, several embodiments are provided to further explain the different implementations of this application. These embodiments are enumerated rather than exhaustive. Furthermore, for the sake of brevity, content mentioned in the preceding embodiments is often omitted in the following embodiments. Therefore, content not mentioned in the following embodiments can be referred to in the preceding embodiments.

[0030] Example 1

[0031] like Figure 1 The diagram shown is a schematic representation of a low-power MEMS thermostatic crystal oscillator based on a diamond thermally conductive layer, as provided in this embodiment. Figure 2 The diagram shows a schematic of the manufacturing process of the MEMS resonator chip with a diamond thermal conductive layer provided in this embodiment.

[0032] In this embodiment, the temperature-controlled crystal oscillator includes a MEMS resonator containing a diamond thermally conductive layer and a heating element, wherein:

[0033] A MEMS resonator containing a diamond thermal conductive layer includes a resonator chip and a diamond thermal conductive layer. The resonator chip and the diamond thermal conductive layer are metallurgically bonded through a wafer-level bonding process, and the area of ​​the diamond thermal conductive layer is matched with the heat-generating area of ​​the resonator chip.

[0034] In one embodiment, the diamond thermal conductive layer is prepared by chemical vapor deposition and is a single-crystal diamond thin film.

[0035] This ensures a reliable heat conduction path. Simultaneously, it achieves comprehensive heat coverage, efficiently dissipating the heat generated during chip operation, helping the resonator maintain a stable temperature environment and guaranteeing its frequency performance.

[0036] The heating element is positioned in the area adjacent to the diamond thermal conductive layer to output the heat required for the resonator chip to heat up.

[0037] In one embodiment, the heating area of ​​the heating element is matched to the area of ​​the diamond thermally conductive layer. The heating element employs an integrated power transistor for heating.

[0038] Based on this, through the close-range layout and area matching design with the diamond thermal conductive layer, the heat generated by the heating element can be quickly and evenly conducted to the MEMS resonator chip through the diamond thermal conductive layer, which efficiently helps the resonator to heat up to the target operating temperature quickly. At the same time, it provides stable energy support for temperature maintenance during the constant temperature stage. Together with the temperature control system, it can achieve precise control of the resonator temperature, ensuring that the resonator always works in a stable temperature range, thereby maintaining the consistency of its frequency performance.

[0039] In one embodiment, the system further includes a thermistor and a temperature control module. The thermistor's sensing end is connected to the diamond thermally conductive layer and is used to acquire the real-time temperature of the resonator chip and feed it back to the temperature control module. The temperature control module dynamically compares the real-time temperature with a preset temperature, calculates the temperature difference and rate of change, and outputs a drive signal to dynamically adjust the power of the heating element, achieving adaptive adjustment between rapid heating and precise temperature maintenance. The thermistor's sensing end is connected to the diamond thermally conductive layer via a highly thermally conductive adhesive.

[0040] Based on this, the thermistor enables the temperature control module to promptly monitor the resonator's temperature status, providing a reliable basis for dynamic adjustment of heating power and ensuring the resonator remains within a stable operating temperature range, thereby guaranteeing the accuracy and stability of its frequency performance. Utilizing the ultra-high thermal conductivity of the diamond thermal layer and its close-proximity arrangement, the temperature control module rapidly and evenly conducts heat to the resonator, offsetting interference from environmental fluctuations and heat loss, stabilizing its optimal temperature range, and ensuring the crystal oscillator's frequency accuracy, stability, and environmental adaptability from the source, providing a reliable frequency reference.

[0041] In one embodiment, the system further includes a thermostatic bath, in which a MEMS resonator containing a diamond thermally conductive layer, a heating element, a thermistor, and a temperature control module are compactly placed. The thermostatic bath employs a lightweight composite thermal insulation cavity structure. The cavity wall adopts a double-layer collaborative design, with the inner layer focusing on efficient heat conduction insulation and the outer layer balancing structural compactness and support reliability.

[0042] Based on this, by optimizing the internal environment to suppress energy loss caused by heat convection, a closed, stable, and controlled thermal environment can be built for the core components, effectively isolating external temperature fluctuations and significantly reducing the power consumption for constant temperature maintenance, which perfectly meets the design requirements of miniaturization and low power consumption of crystal oscillators.

[0043] In summary, the core concept of the low-power MEMS thermostatic crystal oscillator based on a diamond thermal conductive layer disclosed in this embodiment is as follows: Addressing the fundamental problem of low heat transfer efficiency, it introduces diamond (λ≥1000W / m·K, up to 2000W / m·K), with a thermal conductivity far exceeding that of traditional materials, as a dedicated thermal conductive layer. This constructs a low-resistance thermal path from the heating element to the diamond layer and then to the resonator chip. Simultaneously, combined with wafer-level integration technology, it achieves synergistic optimization of heat conduction efficiency, power consumption, and size, resolving multiple contradictions in existing technologies. Compared with existing technologies, it possesses the following significant advantages:

[0044] The preheating time is significantly reduced: the high thermal conductivity of the diamond thermal conductive layer allows heat to penetrate to the core area of ​​the resonator without delay. The thermal time constant is ≤10 seconds, and the preheating time is reduced from 2 to 5 minutes in the traditional solution to 15 to 30 seconds, which meets the instant start-up requirements of 5G communication and portable devices.

[0045] Significantly reduced power consumption: During the preheating stage, the low-resistance thermal path reduces peak power consumption to 0.1-0.5W (compared to 1-5W in traditional solutions), resulting in a power consumption reduction of ≥60%; During the steady-state stage, due to uniform temperature distribution and rapid temperature control response, the power consumption is maintained at ≤0.1W (compared to 0.5-2W in traditional solutions), extending the battery life by 2-5 times, making it suitable for battery-powered scenarios.

[0046] Significantly improved frequency stability: The diamond thermal conductive layer, with its excellent uniform thermal conductivity, significantly optimizes the temperature distribution inside the resonator chip, greatly reducing the temperature gradient compared to traditional solutions and effectively minimizing deformation caused by thermal stress. This characteristic results in a substantial improvement in both the short-term and long-term frequency stability of the resonator, achieving a leap in stability performance compared to traditional solutions and fully meeting the stringent frequency accuracy requirements of high-end communications, test and measurement, and other fields.

[0047] Compact and highly compatible: This design boasts a compact structure and strong compatibility. The diamond thermal conductive layer is integrated with the MEMS wafer using a bonding process. Its ultra-thin design does not occupy additional space, effectively maintaining the miniaturization advantage of the device. The bonding process is highly compatible with existing silicon-based MEMS mass production processes, requiring no additional modifications to the production line. This helps control industrialization costs, balancing structural compactness and process adaptability, thus facilitating industrialization.

[0048] Improved reliability: Diamond material itself has excellent high temperature resistance, wear resistance and excellent chemical stability. This material advantage can significantly enhance the device's adaptability to harsh environments (such as high temperature, humidity fluctuations, etc.), effectively extend the device's working life, greatly improve the overall operational reliability of the temperature-controlled crystal oscillator, and provide a solid guarantee for its stable application under complex working conditions.

[0049] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A low-power MEMS temperature-controlled crystal oscillator based on a diamond thermally conductive layer, characterized in that, Includes a MEMS resonator with a diamond thermal conductive layer and a heating element, wherein: The MEMS resonator containing a diamond thermal conductive layer includes a resonator chip and a diamond thermal conductive layer. The resonator chip and the diamond thermal conductive layer are metallurgically bonded by a wafer-level bonding process. The area of ​​the diamond thermal conductive layer is matched with the heat-generating area of ​​the resonator chip. The heating element is positioned in the region adjacent to the diamond thermally conductive layer and is used to output the heat required to heat up the resonator chip.

2. The isothermal crystal oscillator according to claim 1, characterized in that, The heating element's heating area is matched with the area of ​​the diamond thermally conductive layer.

3. The isothermal crystal oscillator according to claim 1, characterized in that, The diamond thermal conductive layer is prepared by chemical vapor deposition and is a single-crystal diamond thin film.

4. The isothermal crystal oscillator according to claim 1, characterized in that, The heating element uses an integrated power transistor for heating.

5. The isothermal crystal oscillator according to claim 1, characterized in that, It also includes a thermistor and a temperature control module, among which: The sensing end of the thermistor is connected to the diamond thermal conductive layer to collect the real-time temperature of the resonator chip and feed it back to the temperature control module. The temperature control module is used to dynamically compare the real-time temperature with the preset temperature, calculate the temperature difference and the rate of change, and output a drive signal to dynamically adjust the power of the heating element, so as to achieve adaptive adjustment of rapid heating and precise heat preservation.

6. The isothermal crystal oscillator according to claim 5, characterized in that, The sensing end of the thermistor is connected to the diamond thermally conductive layer through a highly thermally conductive adhesive.

7. The isothermal crystal oscillator according to claim 5, characterized in that, It also includes a constant temperature bath, in which: The MEMS resonator containing a diamond thermal conductive layer, heating element, thermistor, and temperature control module are compactly placed in a constant temperature bath.

8. The isothermal crystal oscillator according to claim 7, characterized in that, The constant temperature bath adopts a lightweight composite heat-insulating cavity structure.

9. The isothermal crystal oscillator according to claim 7, characterized in that, The cavity wall of the constant temperature bath adopts a double-layer collaborative design, with the inner layer focusing on efficient heat conduction blocking and the outer layer taking into account both structural compactness and support reliability.

10. The isothermal crystal oscillator according to claim 1, characterized in that, The core resonant region of the MEMS resonator containing a diamond thermal conductive layer is fabricated using a refined process to ensure stable operating frequency characteristics.

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