MEMS resonator and adjustment method based on modal redistribution

Abstract

The present disclosure provides a MEMS resonator based on modal redistribution, comprising: a substrate; a support structure, one end of which is fixed on the substrate; a resonance unit, provided with an adjustment device, the resonance unit being connected to the other end of the support structure; an electrode, electrically connected to the resonance unit, the electrode being arranged on the side, upper surface and / or lower surface of the resonance unit. The present disclosure is aimed at different application requirements of wireless communication systems, and its structure can be flexibly arranged, thereby achieving optimization of its performance, effectively getting rid of the limitations of the existing lithography precision process level. The MEMS resonator has the advantages of small size, easy processing, and space saving, which is conducive to integration and miniaturization, and promotes the high-end application of MEMS resonators in the field of intelligent sensing.

Description

Technical Field

[0001] The present disclosure relates to a radio frequency micro-electromechanical system, and in particular to a MEMS resonator based on modal redistribution and a method for adjusting the same. Background Art

[0002] Future wireless communication systems will show a development trend of integration, miniaturization, low power consumption, high frequency, and multi-mode. The RF front-end transceiver system has the function of pre-processing RF signals and is an important part of the wireless communication system. The RF resonant devices used in traditional RF front-end transceiver systems mainly include quartz crystal oscillators, surface acoustic wave (SAW) filters, film bulk acoustic wave resonators (FBAR), ceramic filters, LC resonant circuits, etc. However, there are many limiting factors in terms of volume, performance, power consumption, etc. MEMS resonant devices have the advantages of high linearity, high Q value, low power consumption, small size, integration, and low cost. They are one of the ideal choices for future wireless communication systems and have great application potential.

[0003] The frequency stability of traditional MEMS resonant devices is greatly affected by the geometric size of the resonant mode: the smaller the size of the MEMS resonant device, the higher its resonant frequency. However, due to the limitations of the existing photolithography precision process level, the size of the MEMS resonant device that can be manufactured is limited, resulting in many problems such as low frequency, unstable device structure and large space in existing MEMS resonant devices. Therefore, it is urgent to develop a new type of MEMS resonant device with flexible frequency and quality factor adjustment characteristics, which can provide a more flexible design space for MEMS resonant devices, better adapt to processing technology requirements, and better meet the needs of actual applications. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The present disclosure provides a MEMS resonator based on modal redistribution and a frequency and Q value adjustment method thereof, so as to at least solve the above problems existing in the prior art.

[0006] (II) Technical solution

[0007] To achieve the above-mentioned objectives, the present disclosure provides a MEMS resonator based on modal redistribution, comprising: a substrate, a support structure, a resonance unit and an electrode, wherein an adjustment device is provided on the resonance unit, the electrode is arranged on the side, upper surface and / or lower surface of the resonance unit, the resonance unit is electrically connected to the electrode, one end of the support structure is fixed on the substrate, and the other end of the support structure is connected to the resonance unit.

[0008] Optionally, the adjustment device is a load structure, and the number of the load structures is at least one; by adding the load structure, the frequency of the MEMS resonator is reduced, and the Q value of the MEMS resonator is reduced;

[0009] Wherein, the load structure covers the surface of the resonant unit;

[0010] Wherein, the load structure is a graphic structure of a single layer or a multi-layer film; the graphic structure is one or more of a diamond, a circle, a rectangle or a fan.

[0011] Optionally, the adjustment structure is a hole structure, and the number of the hole structures is at least one; by adding the hole structure, the frequency of the MEMS resonator is reduced, and the Q value of the MEMS resonator is reduced;

[0012] The hole structure is a through hole, and its shape includes one or more of diamond, circle, rectangle or fan shape.

[0013] Optionally, the hole structure is partially or completely filled with silicon dioxide or silicon nitride material.

[0014] Optionally, the adjustment device is an angular structure, and the number of angular structures is at least one; by adding the angular structure, the frequency of the MEMS resonator is increased, and the Q value of the MEMS resonator is increased;

[0015] The corner structure is a chamfer, rounded corner or cut corner of the edge of the resonance unit.

[0016] Optionally, the material of the electrode is a semiconductor material or a metal material, the semiconductor material is single crystal silicon or polycrystalline silicon, and the metal material is chromium gold.

[0017] Optionally, the material of the resonance unit is a semiconductor material or a metal material, and the semiconductor material is any one of single crystal silicon, polycrystalline silicon and silicon dioxide, or a composite material of a combination of at least two of these materials.

[0018] Optionally, the energy conversion mode between the resonance unit and the electrode includes electrostatic, piezoelectric, thermoelectric, piezoresistive and electromagnetic.

[0019] Optionally, the support structure is one or more of a straight beam structure, an arc beam structure or a frame beam structure, and the material of the support structure is a semiconductor or metal material, such as single crystal silicon, polycrystalline silicon, silicon dioxide or a composite material composed of at least two of them.

[0020] The present invention also provides a method for adjusting the above-mentioned MEMS resonator based on modal redistribution, including: changing the geometric shape, size, distribution position and material properties of the adjustment device, controlling the modal redistribution effect, so as to adjust the frequency and Q value of the MEMS resonator based on modal redistribution to the desired frequency and Q value. When the hole structure is added to the resonance unit, the frequency of the MEMS resonator decreases, and the Q value of the MEMS resonator decreases; when the angular structure is added to the resonance unit, the frequency of the MEMS resonator increases, and the Q value of the MEMS resonator increases; after the load structure is set in the resonance unit, the frequency of the MEMS resonator decreases, and the Q value of the MEMS resonator decreases.

[0021] (III) Beneficial effects

[0022] It can be seen from the above technical solution that the beneficial effects of the present invention are:

[0023] (1) The present invention discloses a MEMS resonator based on modal redistribution. The structure of the MEMS resonator can be flexibly set to meet the different application requirements of wireless communication systems, thereby optimizing its performance and effectively breaking away from the limitations of existing photolithography precision process levels. The MEMS resonator has the advantages of small size, easy processing, and space saving, which is conducive to integration and miniaturization, and promotes the high-end application of MEMS resonators in the field of intelligent sensing.

[0024] (2) The present invention discloses a method for adjusting the frequency and Q value of a MEMS resonator based on modal redistribution. The method adjusts the internal device size of the MEMS resonator to adjust its frequency and Q value, thereby overcoming the disadvantage that the resonator frequency is limited by the geometric size, achieving fine-tuning of a certain device size to cover a larger frequency range, shortening the device R&D cycle, significantly reducing the device development cost, and improving the market competitiveness of the MEMS resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of a MEMS resonator;

[0026] Figure 2 It is a schematic diagram of the modal redistribution of the resonant unit.

[0027]

Explanation of symbols

[0028] 1-Resonance unit;

[0029] 2-pore structure;

[0030] 3-Rounded corner structure;

[0031] 4-Electrode;

[0032] 5- Support structure;

[0033] 6-Substrate. DETAILED DESCRIPTION

[0034] The present disclosure provides a MEMS resonator based on modal redistribution and an adjustment method thereof. The MEMS resonator based on modal redistribution includes a substrate, a support structure, a resonance unit and an electrode, wherein one end of the support structure is connected to the resonance unit, and the other end is fixed on the substrate, so as to support the resonance unit so that it can be suspended; the electrode is electrically connected to the resonance unit, and the electrode is distributed on the side, upper surface and / or lower surface of the resonance unit; the resonance unit is suspended above the substrate, and an adjustment structure is provided on the resonance unit, and the frequency and Q value of the MEMS resonator can be adjusted by controlling the size and number of the adjustment structure.

[0035] The adjustment structure includes one or more of a hole structure, an angle structure or a load structure covering the surface of the resonance unit.

[0036] For example: the adjustment structure includes a hole structure and an angle structure, or includes a hole structure and a load structure, or includes an angle structure and a load structure, or includes a hole structure, an angle structure and a load structure, or includes only a hole structure, or only includes an angle structure, or only includes a load structure.

[0037] The hole structure is partially or completely filled with silicon dioxide or silicon nitride material. The hole structure is a through hole, and its shape can be selected from one or more of diamond, circle, rectangle or fan.

[0038] The corner structure can be obtained by chamfering, rounding or cutting the resonant unit.

[0039] The load structure is a graphic structure of a single layer or a multilayer thin film, and the graphic structure includes one or more of diamond, circle, rectangle or fan shape, and its growth mode can be selected from one or more of evaporation, sputtering, coating, deposition or electrochemistry.

[0040] The electrode material, the resonance unit material and the support structure material of the MEMS resonator can be selected from semiconductor or metal materials, such as single crystal silicon, polycrystalline silicon or chrome gold.

[0041] The resonance unit is made by micromachining technology, and the energy conversion modes between the resonance unit and the electrode include electrostatic, piezoelectric, thermoelectric, piezoresistive and electromagnetic.

[0042] The supporting structure is one or more of a straight beam structure, an arc beam structure or a frame beam structure.

[0043] The present disclosure also provides a method for adjusting the frequency and Q value of the above-mentioned MEMS resonator based on modal redistribution, the steps of which include: when a hole structure is added in the resonance unit, the frequency of the MEMS resonator is reduced, and the Q value of the MEMS resonator is reduced; when an angle structure is added in the resonance unit, the frequency of the MEMS resonator is increased, and the Q value of the MEMS resonator is increased; after a load structure is set in the resonance unit, the frequency of the MEMS resonator is reduced, and the Q value of the MEMS resonator is reduced.

[0044] The structure of the above-mentioned MEMS resonator based on modal redistribution can be flexibly set to meet the different application requirements of wireless communication systems, thereby optimizing its performance and effectively getting rid of the limitations of existing lithography precision process levels. The MEMS resonator has the advantages of small size, easy processing, and space saving, which is conducive to integration and miniaturization, and promotes the high-end application of MEMS resonators in the field of intelligent sensing.

[0045] In order to make the purpose, technical scheme and advantages of the present disclosure more clear, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. However, the present disclosure can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and fully convey the scope of the present disclosure to those skilled in the art. In the accompanying drawings, for clarity, the sizes and relative sizes of layers and regions may be exaggerated, and the same reference numerals represent the same elements throughout.

[0046] Embodiment 1:

[0047] The present disclosure provides a MEMS resonator based on modal redistribution, such as Figure 1 As shown, the MEMS resonator based on modal redistribution includes:

[0048] A resonance unit 1 , two electrodes 4 , two support structures 5 and two substrates 6 .

[0049] Among them, the substrate 6 is the anchoring structure of the resonance unit 1 on the chip; the material of the electrode 4 is chrome gold, and the electrode 4 is arranged on two opposite sides of the resonance unit 1 to apply driving excitation to the MEMS resonator; one end of the support structure 5 is connected to the resonance unit 1, and the other end is fixed on the substrate 6 to support the resonance unit 1 in suspension; the material of the resonance unit 1 is polycrystalline silicon, and the resonance unit 1 is obtained by a micromachining process, and its vibration mode is a surface tensile mode. The resonance unit 1 and the electrode 4 constitute a transducer structure, and its transducer mode is electrostatic.

[0050] The resonance unit 1 is provided with a hole structure 2 and a rounded corner structure 3 .

[0051] The hole structure 2 is a rectangular through hole.

[0052] The rounded corner structure 3 is obtained by rounding the four corners of the resonance unit 1 .

[0053] The support structure 5 is a straight beam structure, and the support structure 5 is made of polycrystalline silicon semiconductor material.

[0054] Figure 2 Schematic diagram of the modal redistribution of the resonance unit 1 in the first embodiment, that is, a diagram showing the modal redistribution effect of the resonance unit 1 after the hole structure 2 and the rounded structure 3 are introduced. Figure 2 The darker part indicates a small displacement, and the lighter part indicates a large displacement. Figure 2 It can be seen that after the hole structure 2 and the rounded corner structure 3 are introduced into the resonance unit 1, the displacement distribution changes, the mode is redistributed, and its energy distribution is more concentrated.

[0055] The modes of the MEMS resonator in the first embodiment are redistributed, and the energy is concentrated in the middle of the resonance unit 1, which effectively gets rid of the limitation of the existing photolithography precision process level, and has the advantages of small size, easy processing, and space saving.

[0056] Embodiment 2:

[0057] The present disclosure also provides a method for determining the frequency and Q value of a MEMS resonator based on modal redistribution in Embodiment 1, comprising the following steps:

[0058] When a hole structure is added to the resonance unit, the frequency of the MEMS resonator decreases and the Q value of the MEMS resonator decreases; when an angular structure is added to the resonance unit, the frequency of the MEMS resonator increases and the Q value of the MEMS resonator increases; after a load structure is set in the resonance unit, the frequency of the MEMS resonator decreases and the Q value of the MEMS resonator decreases.

[0059] The above-mentioned adjustment method adjusts the frequency and Q value of the MEMS resonator by adjusting the internal device size of the MEMS resonator, thereby overcoming the disadvantage that the resonator frequency is limited by the geometric size, achieving fine-tuning of a certain device size to cover a larger frequency range, shortening the device R&D cycle, significantly reducing the device development cost, and improving the market competitiveness of the MEMS resonator.

[0060] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure, and the shapes and sizes of the components in the drawings do not reflect the actual size and proportion, but only illustrate the contents of the embodiments of the present disclosure.

[0061] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0062] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A MEMS resonator based on modal redistribution, comprising: substrate; A support structure, one end of which is fixed on the substrate; A resonance unit connected to the other end of the support structure; The resonance unit is provided with an adjustment device, wherein the adjustment device includes at least one of a load structure, a hole structure, and an angle structure; An electrode electrically connected to the resonance unit; the electrode is arranged on the side, upper surface and / or lower surface of the resonance unit; Wherein, when the adjustment device includes the load structure, the number of the load structure is at least one; by adding the load structure, the frequency of the MEMS resonator is reduced and the Q value of the MEMS resonator is reduced; Wherein, the load structure covers the surface of the resonance unit; Wherein, the load structure is a graphic structure of a single layer or a multi-layer thin film; the graphic structure is one or more of a diamond, a circle, a rectangle or a fan; Wherein, in the case where the adjustment device includes the hole structure, the number of the hole structure is at least one; by adding the hole structure, the frequency of the MEMS resonator is reduced, and the Q value of the MEMS resonator is reduced, and the hole structure is a through hole, and its shape includes one or more of a rhombus, a circle, a rectangle or a fan; Wherein, when the adjustment device includes an angle structure, the number of the angle structure is at least one; by adding the angle structure, the frequency of the MEMS resonator is increased and the Q value of the MEMS resonator is increased, and the angle structure is a chamfer, fillet or cut corner of the edge of the resonance unit.

2. A MEMS resonator based on modal redistribution according to claim 1, wherein: The hole structure is partially or completely filled with silicon dioxide or silicon nitride material.

3. A MEMS resonator based on modal redistribution according to claim 1, wherein: The material of the electrode is a semiconductor material or a metal material, the semiconductor material is single crystal silicon or polycrystalline silicon, and the metal material is chromium gold.

4. A MEMS resonator based on modal redistribution according to claim 1, wherein: The material of the resonance unit is a semiconductor material or a metal material, and the semiconductor material is any one of single crystal silicon, polycrystalline silicon and silicon dioxide, or a composite material of at least two of them.

5. A MEMS resonator based on modal redistribution according to claim 1, wherein: The energy conversion modes between the resonance unit and the electrode include electrostatic, piezoelectric, thermoelectric, piezoresistive and electromagnetic.

6. A MEMS resonator based on modal redistribution according to claim 1, wherein: The support structure is one or more of a straight beam structure, an arc beam structure or a frame beam structure. The material of the support structure is a semiconductor or a metal material. The semiconductor material is any one of single crystal silicon, polycrystalline silicon and silicon dioxide or a composite material of a combination of at least two of these materials.

7. A method for adjusting a MEMS resonator based on modal redistribution as claimed in any one of claims 1 to 6, comprising: The geometric shape, size, distribution position and material properties of the adjustment device are changed to control the modal redistribution effect, so as to adjust the frequency and Q value of the MEMS resonator based on modal redistribution to the desired frequency and Q value.

Images