阅读说明：本技术 基于周期性弹性波反射结构的静电式谐振器 (Electrostatic resonator based on periodic elastic wave reflection structure ) 是由 贾倩倩 杨晋玲 袁泉 陈泽基 刘文立 杨富华 于 2020-12-31 设计创作，主要内容包括：本公开提供了一种基于周期性弹性波反射结构的静电式谐振器,包括：谐振单元；电极,与谐振单元电连接；介质层,设于谐振单元与电极之间；支撑结构,支撑结构的一端与谐振单元相连,支撑结构的另一端固定在基底上；基底包括至少一个层状结构；周期性弹性波反射结构,设置在基底上；其中,周期性弹性波反射结构包括至少一个最小重复单元,最小重复单元为孔状结构。本公开的周期性弹性波反射结构能够在谐振器基底形成阻带,从而进一步降低谐振器锚点损耗,大幅度稳定提升谐振器品质因子。该谐振器具有普适性,解决了MEMS谐振器高频下保持较高的品质因子的瓶颈问题。(The present disclosure provides an electrostatic resonator based on a periodic elastic wave reflection structure, including: a resonance unit; an electrode electrically connected to the resonance unit; the dielectric layer is arranged between the resonance unit and the electrode; one end of the supporting structure is connected with the resonance unit, and the other end of the supporting structure is fixed on the substrate; the substrate comprises at least one layered structure; a periodic elastic wave reflection structure disposed on the substrate; wherein the periodic elastic wave reflection structure comprises at least one minimum repeating unit, and the minimum repeating unit is a porous structure. The periodic elastic wave reflection structure can form a stop band on the substrate of the resonator, so that anchor point loss of the resonator is further reduced, and quality factors of the resonator are greatly and stably improved. The resonator has universality and solves the bottleneck problem of keeping a higher quality factor under the high frequency of the MEMS resonator.)

1. An electrostatic resonator based on a periodic elastic wave reflective structure, comprising:

a resonance unit;

an electrode electrically connected to the resonance unit;

the dielectric layer is arranged between the resonance unit and the electrode;

one end of the supporting structure is connected with the resonance unit, and the other end of the supporting structure is fixed on the substrate; the substrate comprises at least one layered structure;

a periodic elastic wave reflective structure disposed on the substrate;

wherein the periodic elastic wave reflective structure includes at least one minimal repeating unit, and the minimal repeating unit is a hole-like structure.

2. The electrostatic resonator of claim 1, wherein the aperture-like structure is one or more of square, circular or cross-shaped in shape.

3. The electrostatic resonator of claim 1, wherein the minimal repeating unit is arranged in a shape of a planar line, a polygon, or a combination thereof.

4. The electrostatic resonator of claim 1, wherein the minimal repeating unit is disposed on each of the layered structures, respectively, and the minimal repeating unit axes on adjacent layered structures do not coincide.

5. The electrostatic resonator of claim 1, wherein the minimal repeating unit is completely or partially filled with at least two materials having a distinct difference in acoustic impedance.

6. The electrostatic resonator according to any of claims 1 to 5, wherein the resonant cell, the support structure and the substrate are in the same plane or form an interlayer interconnection from top to bottom in sequence.

7. The electrostatic resonator according to claim 1, wherein the resonance unit vibration mode is any one of an in-plane tensile mode, an in-plane shear mode, an in-plane bending mode, an out-of-plane shear mode, or an out-of-plane torsional mode.

8. The electrostatic resonator of claim 1, wherein the support structure is one or more of a straight beam structure, an arc beam structure, or a frame beam structure.

9. The electrostatic resonator according to claim 1, wherein the electrodes are provided at a side, upper surface and/or lower surface of the resonance unit.

10. The electrostatic resonator of any one of claims 1 to 5, wherein the dielectric layer has a thickness in the range of 1nm to 1000nm, the dielectric layer being partially or completely filled with a solid dielectric material.

Technical Field

The present disclosure relates to radio frequency micro-electromechanical systems, and more particularly, to an electrostatic high quality factor resonator based on a periodic elastic wave reflective structure.

Background

In the future, wireless communication systems show development trends of integration, miniaturization, low power consumption, high frequency and multiple modes, and the radio frequency front end receiving and transmitting system has a function of preprocessing radio frequency signals and is an important component of the wireless communication systems. The radio frequency resonance devices adopted by the traditional radio frequency front end receiving and transmitting system mainly comprise a quartz crystal oscillator, a Surface Acoustic Wave (SAW) filter, a Film Bulk Acoustic Resonator (FBAR), a ceramic filter, an LC resonance circuit and the like. However, the conventional radio frequency device has many limiting factors in the aspects of volume, performance, power consumption and the like, for example, the resonant frequency of the FBAR is determined by the thickness, the multi-resonant mode is difficult to realize, and the film thickness is difficult to accurately control; the quartz crystal oscillator has low resonant frequency, needs an additional frequency doubling circuit and has larger power consumption. The MEMS resonant device has the advantages of high linearity, high Q value, low power consumption, small size, integration, low cost and the like, is one of ideal choices of a future wireless communication system, and has great application potential.

MEMS resonators can be classified into electrothermal, electromagnetic, piezoelectric, and electrostatic types according to their driving methods. Compared with other three driving modes, the electrostatic resonator has the characteristics of simple structure, low process difficulty, compatibility with an IC (integrated circuit) process, low power consumption, quick response and high Q value, and has wide application prospect in the aspect of realizing a full-silicon integrated monolithic radio frequency system.

High frequency, high Q-factor is one of the main goals for MEMS resonator performance optimization. The high Q value can reduce the insertion loss of the device and relax the gain requirement of the back-end circuit, thereby reducing the power consumption of the system; high frequencies can meet the frequency band requirements of wireless communication systems. It is known that during the electromechanical conversion process of the resonator, a large amount of sound waves are propagated through the support beam to the substrate, resulting in a severe energy loss, which is referred to as anchor point loss. The anchor point loss can significantly reduce the device Q value, thereby severely limiting the practical application of the electrostatic MEMS resonator. The conventional electrostatic resonator reduces the geometric dimension of a device supporting structure to reduce anchor point loss and improve quality factors. However, at higher frequencies, the device geometry is smaller, and to achieve higher quality factors, the size of the support structure needs to be further reduced, which is limited by the precision of the lithography process. The current realization of maintaining a high quality factor at high frequencies remains a bottleneck problem in the development of MEMS resonators. Therefore, there is a strong need to develop an electrostatic MEMS resonator with high frequency, high quality factor and without process accuracy limitation.

Disclosure of Invention

Technical problem to be solved

The present disclosure provides an electrostatic high quality factor resonator based on a periodic elastic wave reflection structure to at least solve the above-mentioned problems in the prior art.

(II) technical scheme

To achieve the above object, the present disclosure provides an electrostatic resonator based on a periodic elastic wave reflection structure, including: the device comprises a resonance unit, electrodes, a dielectric layer, a support structure and a periodic elastic wave reflection structure. Wherein the electrode is electrically connected with the resonance unit; the dielectric layer is arranged between the resonance unit and the electrode; one end of the supporting structure is connected with the resonance unit, and the other end of the supporting structure is fixed on the substrate; the substrate comprises at least one layered structure; the periodic elastic wave reflective structure is disposed on the substrate, wherein the periodic elastic wave reflective structure includes at least one minimum repeating unit, and the minimum repeating unit is a hole-like structure.

Optionally, the shape of the hole-like structure is one or more of a square, a circle or a cross.

Optionally, the arrangement shape of the minimal repeating unit is planar linear, polygonal or a combination thereof.

Optionally, the minimal repeating unit is respectively arranged on each layered structure, and the minimal repeating unit axes on adjacent layered structures are not coincident.

Optionally, the minimal repeating unit is completely or partially filled with at least two materials with distinct differences in acoustic impedance.

Optionally, the resonant unit, the support structure and the substrate are in the same plane or sequentially form an interlayer interconnection from top to bottom.

Optionally, the resonant unit vibration mode is any one of an in-plane tensile mode, an in-plane shear mode, an in-plane bending mode, an out-of-plane shear mode, or an out-of-plane torsion mode.

Optionally, the support structure is one or more of a straight beam structure, an arc beam structure or a frame beam structure.

Optionally, the electrodes are arranged at the sides, upper surface and/or lower surface of the resonator element.

Optionally, the thickness of the dielectric layer ranges from 1nm to 1000nm, and the dielectric layer is partially or completely filled with a solid dielectric material.

(III) advantageous effects

According to the technical scheme, the beneficial effects of the disclosure are as follows:

(1) the periodic elastic wave reflection structure can form a stop band on the substrate of the resonator, so that anchor point loss of the resonator is further reduced, and quality factors of the resonator are greatly and stably improved. The resonator has universality and solves the bottleneck problem of keeping a higher quality factor under the high frequency of the MEMS resonator.

(2) The resonator disclosed by the invention is small in size and has a high quality factor, the limitation of photoetching precision is effectively avoided, the processing is easy, the yield is improved, the large-scale batch production of devices is realized, the cost is obviously reduced, and the practical process of the MEMS resonator is promoted.

Drawings

FIG. 1 is a schematic diagram of an electrostatic resonator structure based on a periodic elastic wave reflective structure according to an embodiment of the present disclosure;

fig. 2 is a schematic diagram of a resonance mode of the resonance unit of fig. 1.

[ notation ] to show

1: a resonance unit;

2: an electrode;

3: a dielectric layer;

4: a substrate;

5: a support structure;

6: a minimal repeating unit;

7: a periodic elastic wave reflective structure.

Detailed Description

The present disclosure provides an electrostatic resonator based on a periodic elastic wave reflection structure, which includes a resonance unit, an electrode, a dielectric layer, a substrate, a support structure, and a periodic elastic wave reflection structure. The periodic elastic wave reflection structure is formed by arranging the minimum repeating unit on the substrate, so that a stop band is formed on the resonator substrate, the anchor point loss of the resonator is further reduced, and the quality factor of the resonator is greatly and stably improved. In addition, the resonator is small in size and has a high quality factor, the limitation of photoetching precision is effectively avoided, the processing is easy, the yield is improved, the large-scale batch production of devices is realized, the cost is reduced remarkably, the practical process of the MEMS resonator is promoted, the universality is realized, and the bottleneck problem that the high quality factor is kept under the high frequency of the existing MEMS resonator is solved.

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings. This disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity, and like reference numerals designate like elements throughout.

As shown in fig. 1, the present embodiment provides an electrostatic resonator based on a periodic elastic wave reflection structure, and as shown in fig. 1, the electrostatic resonator based on the periodic elastic wave reflection structure includes: a resonant cell 1, two electrodes 2, two dielectric layers 3, a substrate 4 and a support structure 5.

The following describes each component of the electrostatic resonator based on the periodic elastic wave reflection structure and the connection relationship thereof in detail.

The resonance unit 1 is electrically connected with the two electrodes 2, and the two electrodes 2 are respectively arranged on two opposite side surfaces of the resonance unit 1, so that the electrodes 2 and the resonance unit 1 form two gaps, and the two dielectric layers 3 are respectively arranged in the two gaps. The supporting structure 5 is a straight beam structure and serves as a supporting anchor point of the resonance unit 1, one end of the supporting structure is connected with the resonance unit 1, and the other end of the supporting structure is fixed on the substrate 4, so that the resonance unit 1 is arranged in a suspended mode.

The vibration mode of the resonance unit 1 is an in-plane shear mode, and the material thereof is polysilicon. The material of the electrode 2 is monocrystalline silicon. The dielectric layer 3 between the electrode 2 and the resonance unit 1 is made of hafnium oxide, and the thickness of the hafnium oxide is 70 nm.

The resonance unit 1, which is the main body of the resonator, is used to generate mechanical vibrations.

The electrode 2 and the resonance unit 1 constitute a transduction assembly for applying a driving excitation to the resonator and performing the extraction of the resonance signal.

The substrate 4 is a layered structure, and is used as an anchoring structure of the resonant unit on the chip substrate, and a minimal repeating unit 6 is disposed thereon, as shown in fig. 1, the minimal repeating unit 6 is a cross-shaped through hole, and a portion of the through hole is filled with silicon dioxide, which forms a periodic elastic wave reflection mechanism 7 by a planar rectangular and linear arrangement manner. The periodic elastic wave reflection mechanism 7 is used for forming an acoustic wave transmission stop band within a specific frequency range, covering the working frequency of the resonator, and suppressing the diffusion of elastic waves in the stop band in the substrate 4, so that the energy carried by the elastic waves is reflected back to the resonance unit 1.

Fig. 2 is a schematic diagram of the resonant mode of the resonant unit 1 in the first embodiment, that is, a modal redistribution effect of the resonant unit 1 after the periodic elastic wave reflection structure 7 is introduced. In fig. 2, dark portions indicate small displacements, and light portions indicate large displacements. As can be seen from fig. 2, when the substrate 4 is introduced into the periodic elastic wave reflection structure 7, the displacement distribution changes, the mode is redistributed, and the energy distribution is more concentrated.

The quality factor of the electrostatic resonator can be improved by 3-5 times compared with the quality factor of the conventional resonator, and the electrostatic resonator can be applied to but not limited to oscillators or filter devices.

In conclusion, the present disclosure provides an electrostatic resonator based on a periodic elastic wave reflection structure, which has a high quality factor, and effectively avoids the limitation of the photolithography precision level in the prior art, so that the electrostatic resonator is easy to process, has a high yield, and can implement large-scale mass production.

It should also be noted that directional terms, such as "upper", "lower", "front", "rear", "left", "right", and the like, used in the embodiments are only directions referring to the drawings, and are not intended to limit the scope of the present disclosure. Throughout the drawings, like elements are represented by like or similar reference numerals. In the event of possible confusion for understanding of the present disclosure, conventional structures or configurations will be omitted, and the shapes and sizes of the components in the drawings do not reflect actual sizes and proportions, but merely illustrate the contents of the embodiments of the present disclosure.

Unless otherwise indicated, the numerical parameters set forth in the specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. In particular, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Generally, the expression is meant to encompass variations of ± 10% in some embodiments, 5% in some embodiments, 1% in some embodiments, 0.5% in some embodiments by the specified amount.

The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify a corresponding element does not by itself connote any ordinal number of the element or any ordering of one element from another or the order of manufacture, and the use of the ordinal numbers is only used to distinguish one element having a certain name from another element having a same name.

In addition, unless steps are specifically described or must occur in sequence, the order of the steps is not limited to that listed above and may be changed or rearranged as desired by the desired design. The embodiments described above may be mixed and matched with each other or with other embodiments based on design and reliability considerations, i.e., technical features in different embodiments may be freely combined to form further embodiments.

The above-mentioned embodiments are intended to illustrate the objects, aspects and advantages of the present disclosure in further detail, and it should be understood that the above-mentioned embodiments are only illustrative of the present disclosure and are not intended to limit the present disclosure, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present disclosure should be included in the scope of the present disclosure.