WO2022226913A1 - Piezoelectric mems silicon resonator and electronic device - Google Patents

Piezoelectric mems silicon resonator and electronic device Download PDF

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Publication number
WO2022226913A1
WO2022226913A1 PCT/CN2021/091099 CN2021091099W WO2022226913A1 WO 2022226913 A1 WO2022226913 A1 WO 2022226913A1 CN 2021091099 W CN2021091099 W CN 2021091099W WO 2022226913 A1 WO2022226913 A1 WO 2022226913A1
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doping concentration
silicon
temperature compensation
piezoelectric
layer
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PCT/CN2021/091099
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French (fr)
Chinese (zh)
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张孟伦
杨清瑞
宫少波
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天津大学
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Priority to PCT/CN2021/091099 priority Critical patent/WO2022226913A1/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details

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  • the invention relates to the technical field of resonators, in particular to a piezoelectric MEMS silicon resonator and electronic equipment.
  • the resonant frequency of the resonator drifts with temperature.
  • the sensitivity of the resonant frequency of the device to temperature changes can be represented by the temperature coefficient of frequency (TCF, temperature coefficient of frequency), which means the amount of change in the resonant frequency per degree change in temperature.
  • TCF temperature coefficient of frequency
  • the equivalent frequency temperature coefficient is the weighted average of the frequency temperature coefficients of each layer of materials, which can be expressed as:
  • ⁇ n is the composite equivalent frequency temperature coefficient
  • E i , t i are the Young's modulus and weight (eg thickness) of the i-th layer material, respectively. Therefore, the adjustment of the equivalent TCF of the composite structure can be realized by adjusting the weight ratio between the materials of each layer, the Young's modulus and the TCF of each order, so that it is zero or approximately zero in a certain temperature range, thereby improving the performance of the device. stability.
  • the TCF of the resonator can be adjusted by adjusting the thickness ratio between the layers and selecting the single crystal silicon phase.
  • the frequency temperature coefficient of single crystal silicon will change with the doping concentration, and the doping type can be p -type or n-type doping . It can control the frequency temperature coefficient of the entire resonator, and even change the frequency temperature coefficient of the resonator from negative to positive.
  • the Young's modulus and stiffness of single crystal silicon are different along different crystal directions, the frequency temperature coefficient of the single crystal silicon resonator can also be adjusted through the selection of crystal directions.
  • a resonator has a composite structure cantilever beam composed of an upper electrode, an AlN piezoelectric layer, a lower electrode, and a silicon temperature compensation layer, and the temperature coefficient of the first-order frequency of AlN is about -30ppm/K
  • the single crystal can be adjusted.
  • the doping concentration of silicon makes the temperature coefficient of the first-order frequency of the whole resonator close to 0ppm/K, and at the same time, the thickness ratio between the layers can be adjusted and the crystal orientation of single crystal silicon can be adjusted, so that the TCF is equal to or close to zero, so as to achieve Purpose of temperature compensation.
  • this method is difficult to take into account the high-order frequency temperature coefficient, and the quality factor and electromechanical coupling coefficient of the resonator may be deteriorated accordingly.
  • the present invention proposes a piezoelectric MEMS silicon resonator structure for fine temperature compensation, which can improve the performance and reliability of the resonator as a whole.
  • a first aspect of the present invention provides a piezoelectric MEMS silicon resonator.
  • the resonant structure in the device includes a stacked electrode layer, a piezoelectric layer, and a non-uniformly doped silicon temperature compensation layer, the non-uniformly doped silicon temperature compensation layer.
  • the complementary layer contains at least two different doping concentrations, and/or, at least two different doping elements.
  • the stress distribution in the piezoelectric layer and the doping concentration distribution of the silicon temperature compensation layer contains at least two different doping concentrations
  • the stress distribution in the piezoelectric layer and the doping concentration distribution of the silicon temperature compensation layer The following preset correspondence rules are satisfied between the two: when the resonant structure works in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than the thickness of the silicon temperature compensation layer, the piezoelectric layer in the The stress distribution is positively correlated with the doping concentration distribution of the silicon temperature compensation layer; when the resonant structure works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than the silicon temperature In the case of the thickness of the compensation layer, the stress distribution in the piezoelectric layer is negatively correlated with the doping concentration distribution of the silicon temperature compensation layer.
  • the resonance structure is a cantilever beam, a fixed beam, a simply supported beam or a diaphragm.
  • the resonance structure is a cantilever beam extending along a first direction
  • the cantilever beam includes the electrode layer, the piezoelectric layer and the non-uniformly doped silicon temperature stacked along the second direction.
  • the complementary layer wherein the first direction and the second direction are perpendicular to each other.
  • the doping concentration is the highest at the position of the first end face near the free end of the cantilever beam, and the doping concentration at the position of the second end face near the fixed end of the cantilever beam is the lowest, and the doping concentration is along the Gradient in the first direction.
  • the doping concentration is the lowest at the position of the first end face near the free end of the cantilever beam, and the doping concentration at the position of the second end face near the fixed end of the cantilever beam is the highest, and the doping concentration is along the Gradient in the first direction.
  • the doping concentration is the lowest at the position of the first center cut plane of the silicon temperature compensation layer, the position of the first end surface near the free end of the cantilever beam and the position near the fixed end of the cantilever beam.
  • the doping concentration is the highest at the position of the second end face, and the doping concentration is gradually graded from the first central cut surface to the first end face and the second end face, wherein the first central cut surface and the first end face and the second end face parallel and equidistant from both.
  • the doping concentration of the first side near the piezoelectric layer is the highest, the doping concentration of the second side far from the piezoelectric layer is the lowest, and the doping concentration is along the The gradient in the second direction is described.
  • the doping concentration of the first side near the piezoelectric layer is the lowest, and the doping concentration of the second side far from the piezoelectric layer is the highest, and the doping concentration is along the line.
  • the gradient in the second direction is described.
  • the doping concentration is the lowest at the second center tangent position of the silicon temperature compensation layer, which is close to the first side surface of the piezoelectric layer and the second side is far away from the piezoelectric layer.
  • the doping concentration at the side position is the highest, and the doping concentration is gradually graded from the second centering tangent to the first and second sides, wherein the second centering tangent is parallel to the first and second sides and The distance to both is equal.
  • the doping concentration is the highest at the second center tangent position of the silicon temperature compensation layer, which is close to the first side surface of the piezoelectric layer and the second side is far away from the piezoelectric layer.
  • the doping concentration at the side position is the lowest, and the doping concentration is gradually graded from the second centering tangent to the first and second sides, wherein the second centering tangent is parallel to the first and second sides and The distance to both is equal.
  • the center point of the silicon temperature compensation layer has the highest doping concentration, which is close to the first side of the piezoelectric layer and far away from the second side of the piezoelectric layer.
  • the first end face position near the free end of the cantilever beam and the second end face position near the fixed end of the cantilever beam have the lowest doping concentration, and the doping concentration is graded from the center point to the periphery.
  • the central point of the silicon temperature compensation layer has the lowest doping concentration, which is close to the first side of the piezoelectric layer and far away from the second side of the piezoelectric layer.
  • the first end face position near the free end of the cantilever beam and the second end face position near the fixed end of the cantilever beam have the highest doping concentration, and the doping concentration is graded from the center point to the periphery.
  • the doping concentration at the position with the highest doping concentration is greater than or equal to 10 19 cm -3 , or greater than or equal to 10 20 cm -3 .
  • a central region in the second direction has a first doping concentration, and other parts have a second doping concentration, and the first doping concentration is greater than the second doping concentration concentration.
  • a position close to the fixed end of the cantilever beam in the first direction has a first doping concentration, and other parts have a second doping concentration, and the first doping concentration is greater than the second doping concentration.
  • a region in the first direction close to the fixed end of the cantilever beam and in the center in the second direction has a first doping concentration, and the remaining parts have a second doping concentration,
  • the first doping concentration is greater than the second doping concentration.
  • the silicon temperature compensation layer has a first doping concentration at a fixed position, and a second doping concentration at other parts, and the first doping concentration is greater than the second doping concentration.
  • the first doping concentration is greater than or equal to 10 19 cm -3 , or greater than or equal to 10 20 cm -3 .
  • a second aspect of the present invention provides an electronic device, which is characterized by comprising the piezoelectric MEMS silicon resonator disclosed in the present invention.
  • an unevenly distributed doping scheme is adopted in the silicon structure of the resonator, and the corresponding doping scheme is designed according to the needs of different parts.
  • Doping concentration to achieve more accurate temperature compensation (such as full compensation of the temperature coefficient of each order frequency).
  • the distribution of the stiffness of the single crystal silicon is adjusted by the concentration distribution. When the stiffness distribution and the stress, strain or displacement field distribution reach a certain mutual match, the electromechanical coupling coefficient of the resonator will be improved.
  • FIG. 1 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a first embodiment of the present invention
  • FIG. 2 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a second embodiment of the present invention
  • FIG. 3 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a third embodiment of the present invention.
  • FIG. 4 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a fourth embodiment of the present invention.
  • FIG. 5 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a fifth embodiment of the present invention.
  • FIG. 6 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a sixth embodiment of the present invention.
  • FIG. 7 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a seventh embodiment of the present invention.
  • FIG. 8 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eighth embodiment of the present invention.
  • FIG. 9 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a ninth embodiment of the present invention.
  • FIG. 10 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a tenth embodiment of the present invention.
  • FIG. 11 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eleventh embodiment of the present invention.
  • FIG. 12 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a twelfth embodiment of the present invention.
  • FIG. 13 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a thirteenth embodiment of the present invention.
  • the resonant structure specifically includes stacked electrode layers, piezoelectric layers and a non-uniformly doped silicon temperature compensation layer, and the non-uniformly doped silicon temperature compensation layer includes at least two The different doping concentrations, and/or, contain at least two different doping elements.
  • the stress distribution in the piezoelectric layer and the doping concentration distribution of the silicon temperature compensation layer satisfy a preset correspondence rule .
  • the resonant structure in the device may be in the form of a cantilever beam, a fixed beam, a simply supported beam, or a diaphragm.
  • the preset corresponding rules may specifically include: (1) When the resonant structure works in the Lamé mode, or when the thickness of the piezoelectric layer is less than the thickness of the silicon temperature compensation layer, the stress distribution in the piezoelectric layer is different from the silicon temperature compensation layer.
  • the piezoelectric MEMS silicon resonator according to an embodiment of the present invention, wherein the resonance structure is a cantilever beam extending along a first direction, and the cantilever beam includes an electrode layer, a piezoelectric layer, and a non-uniformly doped silicon temperature stacked along a second direction.
  • the complementary layer wherein the first direction and the second direction are perpendicular to each other.
  • the piezoelectric layer-electrode layer stack can be located vertically above or vertically below or horizontally to the side of the silicon temperature compensation layer.
  • the number of electrode layers can be two, which are respectively arranged on both sides of the piezoelectric layer; the number of electrode layers can also be only one, the degenerate doped silicon temperature compensation layer is used as another electrode layer, and the silicon temperature compensation layer is connected with a single electrode layer. constitute the working electrode pair.
  • the first direction may be the horizontal direction and the second direction may be the vertical direction, or the first direction may be the x-axis direction in the horizontal plane and the second direction may be the y-axis direction in the horizontal plane, and so on.
  • the specific material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys.
  • non-metallic conductive materials such as doped silicon, can also be used.
  • Piezoelectric layer which can be selected from materials such as aluminum nitride, zinc oxide, and PZT, and includes a rare earth element doped material with a certain atomic ratio of the above materials.
  • Lower electrode same as 101.
  • the lower electrode is an optional structure.
  • the silicon temperature compensation layer is heavily doped or degenerately doped silicon, it can be used as the lower electrode.
  • Silicon temperature compensation layer the material can be selected from monocrystalline silicon, polycrystalline silicon, etc. The darker the color, the higher the doping concentration.
  • the buried oxide layer is an optional structure. If it is not a SOI wafer processing cantilever beam, this structure layer can also be omitted.
  • FIG. 1 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a first embodiment of the present invention.
  • the doping concentration is the highest at the position of the first end face near the free end of the cantilever beam (ie, the left end face in the figure), and the first end face near the fixed end of the cantilever beam has the highest doping concentration.
  • the position of the two end faces ie, the right end face in the figure
  • the doping concentration is graded along the first direction (ie, the horizontal direction in the figure).
  • the doping concentration is higher at the position closer to the free end of the cantilever beam, and the lower the doping concentration is at the position closer to the fixed end of the cantilever beam.
  • the temperature compensation occurs more at the free end with small stress and strain, and the fixed end with large stress and strain does not need too high doping concentration, thus avoiding the excessive change of the rigidity of the fixed end after high concentration doping. Resonant frequency drift. That is, the negative effects of doping are prevented while compensating for temperature.
  • the doping method of this embodiment is preferably selected for temperature compensation.
  • FIG 2 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a second embodiment of the present invention.
  • the doping concentration of the first end face near the free end of the cantilever beam ie the left end face in the figure
  • the doping concentration of the first end face near the fixed end of the cantilever beam is the lowest.
  • the position of the two end faces ie, the right end face in the figure
  • the doping concentration is graded along the first direction (ie, the horizontal direction in the figure).
  • the concentration distribution in the second embodiment is opposite to that in the first embodiment.
  • the heat distribution of the cantilever beam vibration heat generation is considered. Due to the larger stress and strain at the fixed end, more vibrational mechanical energy is converted into heat, so the temperature change at the fixed end is relatively more obvious. Corresponding temperature compensation according to the temperature distribution of each part can keep the resonant frequency of each part stable, and avoid the change of vibration mode due to the inconsistent change of resonant frequency between different parts.
  • the doping method of this embodiment is preferably selected for temperature compensation.
  • FIG. 3 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a third embodiment of the present invention.
  • the doping concentration of the first central tangential plane of the silicon temperature compensation layer is the lowest, and the position of the first end surface close to the free end of the cantilever beam (that is, the The left end face) and the position of the second end face near the fixed end of the cantilever beam shown (that is, the right end face in the figure) have the highest doping concentration, and the doping concentration is graded from the first centering cut to the first end face and the second end face respectively, wherein , the first central tangent plane is parallel to and equidistant from the first and second end faces.
  • the fixed end is designed with a higher doping concentration.
  • more temperature compensation is set near the free end.
  • the doping of this embodiment is preferred. method for temperature compensation.
  • the doping concentration is the highest at the position near the first side of the piezoelectric layer (ie, the top surface in the figure), and the doping concentration at the second side position far away from the piezoelectric layer (ie, the bottom surface in the figure) is the lowest.
  • the doping concentration is graded along the second direction (ie, the vertical direction in the figure).
  • the interface defects reciprocally slide with the vibration to generate thermal energy, so the temperature here changes greatly, and a higher temperature can be designed near the interface. doping concentration.
  • the frequency shift effect caused by the heat distribution is obvious, for example, when the cantilever beam works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer, the doping of this embodiment is preferred. method for temperature compensation.
  • FIG 5 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a fifth embodiment of the present invention.
  • the doping concentration near the first side of the piezoelectric layer that is, the top surface in the figure
  • the position ie, the bottom surface in the figure
  • the doping concentration is graded along the second direction (ie, the vertical direction in the figure).
  • the strain of the bottom surface of the silicon temperature compensation layer is larger than that of the top surface, so the temperature of the bottom surface varies greatly. Therefore, a higher doping concentration is required for the bottom surface.
  • the dopant of this embodiment is preferentially selected. Miscellaneous way to perform temperature compensation.
  • FIG. 6 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a sixth embodiment of the present invention.
  • the doping concentration of the second center section of the silicon temperature compensation layer is the lowest, which is close to the first side position of the piezoelectric layer ( That is, the top surface in the figure) and the second side position away from the piezoelectric layer (that is, the bottom surface in the figure) have the highest doping concentration, and the doping concentration is graded from the second centering cut to the first side and the second side respectively.
  • the second centering tangent is parallel to and equidistant from the first side and the second side.
  • the conditions of the fourth embodiment and the fifth embodiment are comprehensively considered, and the temperature changes of the silicon temperature compensation layer near the upper and lower surfaces are larger, so the required temperature compensation range is also larger.
  • the doping concentration near the upper and lower sides of the silicon temperature compensation layer is higher, and the concentration is lower at the middle position.
  • the doping concentration is the highest at the second center section of the silicon temperature compensation layer, which is close to the first side position of the piezoelectric layer (that is, the top in the figure). surface) and the second side position away from the piezoelectric layer (that is, the bottom surface in the figure), the doping concentration is the lowest, and the doping concentration is graded from the second center to the first side and the second side respectively, wherein the second center The cut plane is parallel to and equidistant from the first side and the second side.
  • the stiffness of the upper and lower sides where the stress is large is changed due to doping.
  • the concentration distribution is designed to be high in the middle and low on the upper and lower sides, so that the stiffness change in the large stress region is not obvious, thus avoiding the frequency drift caused by doping (stiffness change) while taking into account the overall temperature compensation.
  • the doping method of this embodiment is preferably selected for temperature compensation.
  • FIG 8 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eighth embodiment of the present invention.
  • the center point of the silicon temperature compensation layer has the highest doping concentration, which is close to the first side position of the piezoelectric layer (ie, the top surface in the figure).
  • the doping concentration is the lowest, and the doping concentration is gradually graded from the center point to the periphery.
  • the doping method of this embodiment is preferably selected for temperature compensation.
  • FIG. 9 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a ninth embodiment of the present invention.
  • the central point of the silicon temperature compensation layer has the lowest doping concentration, which is close to the first side of the piezoelectric layer (ie, the top surface in the figure).
  • the doping concentration is the highest, and the doping concentration is graded from the center point to the periphery.
  • the distribution of the doping concentration in the ninth embodiment is opposite to that in the eighth embodiment.
  • the doping method of this embodiment is preferentially selected to perform temperature compensation.
  • the doping type can be p-type or n-type doping, when the doping concentration is very high (for example, when the doping concentration is greater than or equal to a preset threshold ), which can control the frequency temperature coefficient of the entire resonator, and even change the frequency temperature coefficient from positive to negative or from negative to positive. Therefore, in the various embodiments shown in FIGS. 1 to 9 , in order to better achieve the temperature compensation effect, the doping concentration at the highest position of the doping concentration is greater than or equal to 10 19 cm ⁇ 3 , and further, the doping concentration is greater than or equal to 10 20 cm -3 .
  • FIG. 10 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a tenth embodiment of the present invention.
  • the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator only the central region in the second direction (ie, the central region in the vertical direction) has the first doping concentration, and the remaining parts have the second doping concentration impurity concentration, the first doping concentration is greater than the second doping concentration.
  • degenerate doping can be performed only in part of the region to achieve the purpose of temperature compensation for a specific position.
  • doping is performed only on the central axis surface of the silicon temperature compensation layer, since there is no strain on this surface, the frequency change caused by the introduction of impurities is avoided to the greatest extent.
  • the dopant of this embodiment is preferentially selected. Miscellaneous way to perform temperature compensation.
  • FIG. 11 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eleventh embodiment of the present invention.
  • the position close to the fixed end of the cantilever beam in the first direction has a first doping concentration, and the other parts have a second doping concentration.
  • the impurity concentration is greater than the second dopant concentration.
  • the eleventh embodiment due to the larger stress and strain at the fixed end, more vibrational mechanical energy is converted into heat, so the temperature change at the fixed end is relatively more obvious.
  • Corresponding temperature compensation according to the temperature distribution of each part can keep the resonant frequency of each part stable, and avoid the change of vibration mode due to the inconsistent change of resonant frequency between different parts.
  • the frequency shift effect caused by doping in the high stress region is smaller than that caused by the heat distribution, such as when the cantilever operates in Lamb mode or bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer
  • the doping method of this embodiment is preferably selected for temperature compensation.
  • FIG. 12 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a twelfth embodiment of the present invention.
  • the region close to the fixed end of the cantilever beam in the first direction and the central region in the second direction (that is, the right end and the vertical direction as shown in the figure)
  • the upper center position has a first doping concentration, and the remaining parts have a second doping concentration, and the first doping concentration is greater than the second doping concentration.
  • doping is only performed in the middle region near the fixed end, which is the region with the most obvious temperature change and the largest stress, and the effect of temperature compensation on this region is obvious.
  • the frequency shift effect caused by the heat distribution is obvious, for example, when the cantilever beam works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer, the doping of this embodiment is preferred. method for temperature compensation.
  • the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator has a first doping concentration at the position of the fixed end, and a second doping concentration at the other parts, and the first doping concentration is greater than the second doping concentration .
  • Doping at the position close to the fixed end of the cantilever beam can also achieve frequency and temperature compensation of the cantilever beam resonator through the mechanical coupling between the fixed end and the cantilever beam; at the same time, since the doping position is not on the cantilever beam, this method can Avoid negative effects caused by cantilever doping, such as Q reduction.
  • high-concentration doping is performed in the fixed region with large stress (here, the fixed region, not the cantilever beam region near the fixed end), increasing the carrier concentration means that the thermal conductivity increases, thus slowing down Temperature drift caused by vibration heat generation.
  • the frequency shift effect caused by the heat distribution is obvious, for example, when the cantilever beam works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer, the doping of this embodiment is preferred. method for temperature compensation.
  • the first doping concentration is greater than or equal to 10 19 cm ⁇ 3 , and further, the first doping concentration is greater than or equal to 10 20 cm -3 .
  • the electronic device includes any piezoelectric MEMS silicon resonator disclosed in the present invention.
  • an unevenly distributed doping scheme is adopted in the silicon structure of the resonator, and the corresponding doping scheme is designed according to the needs of different parts.
  • Doping concentration to achieve more accurate temperature compensation (such as full compensation of the temperature coefficient of each order frequency).
  • the distribution of the stiffness of the single crystal silicon is adjusted by the concentration distribution. When the stiffness distribution and the stress, strain or displacement field distribution reach a certain mutual match, the electromechanical coupling coefficient of the resonator will be improved.

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Abstract

Disclosed in the present invention are a piezoelectric MEMS silicon resonator and an electronic device. The piezoelectric MEMS silicon resonator comprises a cantilever beam provided in a first direction; and the cantilever beam comprises an electrode layer, a piezoelectric layer, and a silicon temperature compensation layer that are stacked in a second direction, wherein the first direction and the second direction are perpendicular to each other, and the silicon temperature compensation layer is made of a non-uniformly doped silicon material. In the present invention, according to parameters such as temperature distribution, stress distribution, and displacement amount distribution of the resonator in a resonant state, a non-uniform distribution doping scheme is used in a silicon structure in the resonator, and corresponding doping concentrations are designed according to requirements of different parts, so as to implement more accurate temperature compensation. In addition, the distribution of the rigidity of monocrystalline silicon is adjusted by means of the concentration distribution; and when the rigidity distribution of the monocrystalline silicon and the stress, strain, or displacement field distribution are matched with each other to a certain extent, an electromechanical coupling coefficient of the resonator is improved.

Description

压电MEMS硅谐振器以及电子设备Piezoelectric MEMS silicon resonators and electronic devices 技术领域technical field
本发明涉及谐振器技术领域，具体涉及一种压电MEMS硅谐振器以及电子设备。The invention relates to the technical field of resonators, in particular to a piezoelectric MEMS silicon resonator and electronic equipment.
背景技术Background technique
由于材料的热胀冷缩效应，谐振器的谐振频率会随温度变化发生漂移。器件的谐振频率对温度变化的灵敏程度可以由频率温度系数(TCF，temperature coefficient of frequency)表示，其涵义为温度每变化一度谐振频率的变化量。对于用多层不同材料构成的复合结构，其等效频率温度系数为每层材料频率温度系数的加权平均值，可表示为：Due to the thermal expansion and contraction effect of the material, the resonant frequency of the resonator drifts with temperature. The sensitivity of the resonant frequency of the device to temperature changes can be represented by the temperature coefficient of frequency (TCF, temperature coefficient of frequency), which means the amount of change in the resonant frequency per degree change in temperature. For a composite structure composed of multiple layers of different materials, the equivalent frequency temperature coefficient is the weighted average of the frequency temperature coefficients of each layer of materials, which can be expressed as:
Figure PCTCN2021091099-appb-000001
Figure PCTCN2021091099-appb-000001
其中，λ n是复合等效频率温度系数，
Figure PCTCN2021091099-appb-000002
是第i层材料的n阶频率温度系数，E i，t i分别是第i层材料的杨氏模量和权重(如厚度)。因此，可通过调节各层材料之间的权重比以及杨氏模量和各阶TCF实现对复合结构等效TCF的调节，使其在一定温度范围内为零或近似为零，从而提高器件的稳定性。 where λ n is the composite equivalent frequency temperature coefficient,
Figure PCTCN2021091099-appb-000002
is the n-order frequency temperature coefficient of the i-th layer material, E i , t i are the Young's modulus and weight (eg thickness) of the i-th layer material, respectively. Therefore, the adjustment of the equivalent TCF of the composite structure can be realized by adjusting the weight ratio between the materials of each layer, the Young's modulus and the TCF of each order, so that it is zero or approximately zero in a certain temperature range, thereby improving the performance of the device. stability.
现有技术中，可以通过调控各层之间的厚度比例以及选择单晶硅晶相来调节谐振器的TCF。一方面，单晶硅的频率温度系数会随着掺杂浓度而改变，掺杂类型可以是p型或者n型掺杂，当掺杂浓度很高时(例如大于等于10 19cm -3)，可以左右整个谐振器频率温度系数，甚至使谐振器的频率温度系数由负变正。另一方面，由于单晶硅在沿不同晶向的杨氏模量和刚度不同，因而也可以通过晶向的选择来调节单晶硅谐振器的频率温度系数。例如，某个谐振器中具有由上电极、AlN压电层、下电极、硅温补层构成的复合结构悬臂梁，AlN的一阶频率温度系数约为-30ppm/K，则可调节单晶硅的掺杂浓度使整个谐振器的一阶频率温度系数接近0ppm/K，同时还 可以调节各层之间的厚度比例及选择单晶硅的晶向，从而使TCF等于或接近零，从而达到温度补偿的目的。但是这种方法难以兼顾高阶频率温度系数，同时谐振器的品质因数和机电耦合系数可能因此恶化。 In the prior art, the TCF of the resonator can be adjusted by adjusting the thickness ratio between the layers and selecting the single crystal silicon phase. On the one hand, the frequency temperature coefficient of single crystal silicon will change with the doping concentration, and the doping type can be p -type or n-type doping . It can control the frequency temperature coefficient of the entire resonator, and even change the frequency temperature coefficient of the resonator from negative to positive. On the other hand, since the Young's modulus and stiffness of single crystal silicon are different along different crystal directions, the frequency temperature coefficient of the single crystal silicon resonator can also be adjusted through the selection of crystal directions. For example, if a resonator has a composite structure cantilever beam composed of an upper electrode, an AlN piezoelectric layer, a lower electrode, and a silicon temperature compensation layer, and the temperature coefficient of the first-order frequency of AlN is about -30ppm/K, the single crystal can be adjusted. The doping concentration of silicon makes the temperature coefficient of the first-order frequency of the whole resonator close to 0ppm/K, and at the same time, the thickness ratio between the layers can be adjusted and the crystal orientation of single crystal silicon can be adjusted, so that the TCF is equal to or close to zero, so as to achieve Purpose of temperature compensation. However, this method is difficult to take into account the high-order frequency temperature coefficient, and the quality factor and electromechanical coupling coefficient of the resonator may be deteriorated accordingly.
发明内容SUMMARY OF THE INVENTION
有鉴于此，本发明提出一种进行精细温度补偿的压电MEMS硅谐振器结构，能够整体提高谐振器的性能和可靠性。In view of this, the present invention proposes a piezoelectric MEMS silicon resonator structure for fine temperature compensation, which can improve the performance and reliability of the resonator as a whole.
本发明第一方面提出一种压电MEMS硅谐振器，器件中的谐振结构包括堆叠设置的电极层、压电层和非均匀掺杂的硅温补层，所述非均匀掺杂的硅温补层包含至少两种不同掺杂浓度，和/或，包含至少两种不同掺杂元素。A first aspect of the present invention provides a piezoelectric MEMS silicon resonator. The resonant structure in the device includes a stacked electrode layer, a piezoelectric layer, and a non-uniformly doped silicon temperature compensation layer, the non-uniformly doped silicon temperature compensation layer. The complementary layer contains at least two different doping concentrations, and/or, at least two different doping elements.
可选地，在所述非均匀掺杂的硅温补层包含至少两种不同掺杂浓度的情况下，所述压电层中应力分布情况与所述硅温补层的掺杂浓度分布情况二者之间满足如下预设对应规则：当所述谐振结构工作在Lamé拉梅模式，或者当所述压电层的厚度小于所述硅温补层厚度的情况下，所述压电层中应力分布情况与所述硅温补层的掺杂浓度分布情况二者呈正相关；当所述谐振结构工作在Lamb兰姆模式或弯曲模式，或者当所述压电层的厚度大于所述硅温补层厚度的情况下，所述压电层中应力分布情况与所述硅温补层的掺杂浓度分布情况二者呈负相关。Optionally, when the non-uniformly doped silicon temperature compensation layer contains at least two different doping concentrations, the stress distribution in the piezoelectric layer and the doping concentration distribution of the silicon temperature compensation layer The following preset correspondence rules are satisfied between the two: when the resonant structure works in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than the thickness of the silicon temperature compensation layer, the piezoelectric layer in the The stress distribution is positively correlated with the doping concentration distribution of the silicon temperature compensation layer; when the resonant structure works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than the silicon temperature In the case of the thickness of the compensation layer, the stress distribution in the piezoelectric layer is negatively correlated with the doping concentration distribution of the silicon temperature compensation layer.
可选地，所述谐振结构为悬臂梁、固支梁、简支梁或者振膜。Optionally, the resonance structure is a cantilever beam, a fixed beam, a simply supported beam or a diaphragm.
可选地，所述谐振结构为沿着第一方向延伸的悬臂梁，所述悬臂梁包括沿第二方向堆叠的所述电极层、所述压电层和所述非均匀掺杂的硅温补层，其中，所述第一方向与所述第二方向互相垂直。Optionally, the resonance structure is a cantilever beam extending along a first direction, and the cantilever beam includes the electrode layer, the piezoelectric layer and the non-uniformly doped silicon temperature stacked along the second direction. The complementary layer, wherein the first direction and the second direction are perpendicular to each other.
可选地，所述硅温补层中，靠近所述悬臂梁的自由端的第一端面位置掺杂浓度最高，靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最低， 掺杂浓度沿着所述第一方向渐变。Optionally, in the silicon temperature compensation layer, the doping concentration is the highest at the position of the first end face near the free end of the cantilever beam, and the doping concentration at the position of the second end face near the fixed end of the cantilever beam is the lowest, and the doping concentration is along the Gradient in the first direction.
可选地，所述硅温补层中，靠近所述悬臂梁的自由端的第一端面位置掺杂浓度最低，靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最高，掺杂浓度沿着所述第一方向渐变。Optionally, in the silicon temperature compensation layer, the doping concentration is the lowest at the position of the first end face near the free end of the cantilever beam, and the doping concentration at the position of the second end face near the fixed end of the cantilever beam is the highest, and the doping concentration is along the Gradient in the first direction.
可选地，所述硅温补层中，所述硅温补层的第一居中切面位置掺杂浓度最低，靠近所述悬臂梁的自由端的第一端面位置和靠近所示悬臂梁的固定端的第二端面位置掺杂浓度最高，掺杂浓度从所述第一居中切面向所述第一端面和第二端面分别渐变，其中，所述第一居中切面与所述第一端面和第二端面平行并且到二者距离相等。Optionally, in the silicon temperature compensation layer, the doping concentration is the lowest at the position of the first center cut plane of the silicon temperature compensation layer, the position of the first end surface near the free end of the cantilever beam and the position near the fixed end of the cantilever beam. The doping concentration is the highest at the position of the second end face, and the doping concentration is gradually graded from the first central cut surface to the first end face and the second end face, wherein the first central cut surface and the first end face and the second end face parallel and equidistant from both.
可选地，所述硅温补层中，靠近所述压电层的第一侧面位置掺杂浓度最高，远离所述压电层的第二侧面位置掺杂浓度最低，掺杂浓度沿着所述第二方向渐变。Optionally, in the silicon temperature compensation layer, the doping concentration of the first side near the piezoelectric layer is the highest, the doping concentration of the second side far from the piezoelectric layer is the lowest, and the doping concentration is along the The gradient in the second direction is described.
可选地，所述硅温补层中，靠近所述压电层的第一侧面位置掺杂浓度最低，远离所述压电层的第二侧面位置掺杂浓度最高，掺杂浓度沿着所述第二方向渐变。Optionally, in the silicon temperature compensation layer, the doping concentration of the first side near the piezoelectric layer is the lowest, and the doping concentration of the second side far from the piezoelectric layer is the highest, and the doping concentration is along the line. The gradient in the second direction is described.
可选地，所述硅温补层中，所述硅温补层的第二居中切面位置掺杂浓度最低，靠近所述压电层的第一侧面位置和远离所述压电层的第二侧面位置掺杂浓度最高，掺杂浓度从所述第二居中切面向所述第一侧面和第二侧面分别渐变，其中，所述第二居中切面与所述第一侧面和第二侧面平行并且到二者距离相等。Optionally, in the silicon temperature compensation layer, the doping concentration is the lowest at the second center tangent position of the silicon temperature compensation layer, which is close to the first side surface of the piezoelectric layer and the second side is far away from the piezoelectric layer. The doping concentration at the side position is the highest, and the doping concentration is gradually graded from the second centering tangent to the first and second sides, wherein the second centering tangent is parallel to the first and second sides and The distance to both is equal.
可选地，所述硅温补层中，所述硅温补层的第二居中切面位置掺杂浓度最高，靠近所述压电层的第一侧面位置和远离所述压电层的第二侧面位置掺杂浓度最低，掺杂浓度从所述第二居中切面向所述第一侧面和第二侧面分别渐变，其中，所述第二居中切面与所述第一侧面和第二侧面平行并 且到二者距离相等。Optionally, in the silicon temperature compensation layer, the doping concentration is the highest at the second center tangent position of the silicon temperature compensation layer, which is close to the first side surface of the piezoelectric layer and the second side is far away from the piezoelectric layer. The doping concentration at the side position is the lowest, and the doping concentration is gradually graded from the second centering tangent to the first and second sides, wherein the second centering tangent is parallel to the first and second sides and The distance to both is equal.
可选地，所述硅温补层中，所述硅温补层的中心点位置掺杂浓度最高，靠近所述压电层的第一侧面位置、远离所述压电层的第二侧面位置、靠近所述悬臂梁的自由端的第一端面位置以及靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最低，掺杂浓度从所述中心点向周围渐变。Optionally, in the silicon temperature compensation layer, the center point of the silicon temperature compensation layer has the highest doping concentration, which is close to the first side of the piezoelectric layer and far away from the second side of the piezoelectric layer. , The first end face position near the free end of the cantilever beam and the second end face position near the fixed end of the cantilever beam have the lowest doping concentration, and the doping concentration is graded from the center point to the periphery.
可选地，所述硅温补层中，所述硅温补层的中心点位置掺杂浓度最低，靠近所述压电层的第一侧面位置、远离所述压电层的第二侧面位置、靠近所述悬臂梁的自由端的第一端面位置以及靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最高，掺杂浓度从所述中心点向周围渐变。Optionally, in the silicon temperature compensation layer, the central point of the silicon temperature compensation layer has the lowest doping concentration, which is close to the first side of the piezoelectric layer and far away from the second side of the piezoelectric layer. , The first end face position near the free end of the cantilever beam and the second end face position near the fixed end of the cantilever beam have the highest doping concentration, and the doping concentration is graded from the center point to the periphery.
可选地，掺杂浓度最高位置的掺杂浓度大于等于10 19cm -3，或者，大于等于10 20cm -3。 Optionally, the doping concentration at the position with the highest doping concentration is greater than or equal to 10 19 cm -3 , or greater than or equal to 10 20 cm -3 .
可选地，所述硅温补层中，在第二方向上的居中区域具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。Optionally, in the silicon temperature compensation layer, a central region in the second direction has a first doping concentration, and other parts have a second doping concentration, and the first doping concentration is greater than the second doping concentration concentration.
可选地，所述硅温补层中，在第一方向上靠近所述悬臂梁的固定端的位置具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。Optionally, in the silicon temperature compensation layer, a position close to the fixed end of the cantilever beam in the first direction has a first doping concentration, and other parts have a second doping concentration, and the first doping concentration is greater than the second doping concentration.
可选地，所述从动层中，在第一方向上靠近所述悬臂梁的固定端并且在第二方向上的居中的区域具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。Optionally, in the driven layer, a region in the first direction close to the fixed end of the cantilever beam and in the center in the second direction has a first doping concentration, and the remaining parts have a second doping concentration, The first doping concentration is greater than the second doping concentration.
可选地，所述硅温补层中，在固定位置具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。Optionally, the silicon temperature compensation layer has a first doping concentration at a fixed position, and a second doping concentration at other parts, and the first doping concentration is greater than the second doping concentration.
可选地，所述硅温补层中，所述第一掺杂浓度掺大于等于10 19cm -3，或者，大于等于10 20cm -3。 Optionally, in the silicon temperature compensation layer, the first doping concentration is greater than or equal to 10 19 cm -3 , or greater than or equal to 10 20 cm -3 .
本发明第二方面提出一种电子设备，其特征在于，包括本发明公开的压电MEMS硅谐振器。A second aspect of the present invention provides an electronic device, which is characterized by comprising the piezoelectric MEMS silicon resonator disclosed in the present invention.
根据本发明的技术方案，依据谐振器在谐振状态下的温度分布、应力分布、位移量分布等参数，在谐振器中硅结构中采用不均匀分布掺杂方案，根据不同部位的需要设计相应的掺杂浓度，实现更精准的温度补偿(如各阶频率温度系数的全补偿)。另外，通过浓度分布调节单晶硅刚度的分布，当其刚度分布与应力、应变或位移场分布达到一定的相互匹配时，谐振器的机电耦合系数将得到提升。According to the technical scheme of the present invention, according to the temperature distribution, stress distribution, displacement distribution and other parameters of the resonator in the resonant state, an unevenly distributed doping scheme is adopted in the silicon structure of the resonator, and the corresponding doping scheme is designed according to the needs of different parts. Doping concentration to achieve more accurate temperature compensation (such as full compensation of the temperature coefficient of each order frequency). In addition, the distribution of the stiffness of the single crystal silicon is adjusted by the concentration distribution. When the stiffness distribution and the stress, strain or displacement field distribution reach a certain mutual match, the electromechanical coupling coefficient of the resonator will be improved.
附图说明Description of drawings
为了说明而非限制的目的，现在将根据本发明的优选实施例、特别是参考附图来描述本发明，其中：For purposes of illustration and not limitation, the present invention will now be described in accordance with preferred embodiments thereof, particularly with reference to the accompanying drawings, wherein:
图1为本发明第一实施例的压电MEMS硅谐振器的剖面示意图；1 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a first embodiment of the present invention;
图2为本发明第二实施例的压电MEMS硅谐振器的剖面示意图；2 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a second embodiment of the present invention;
图3为本发明第三实施例的压电MEMS硅谐振器的剖面示意图；3 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a third embodiment of the present invention;
图4为本发明第四实施例的压电MEMS硅谐振器的剖面示意图；4 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a fourth embodiment of the present invention;
图5为本发明第五实施例的压电MEMS硅谐振器的剖面示意图；5 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a fifth embodiment of the present invention;
图6为本发明第六实施例的压电MEMS硅谐振器的剖面示意图；6 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a sixth embodiment of the present invention;
图7为本发明第七实施例的压电MEMS硅谐振器的剖面示意图；7 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a seventh embodiment of the present invention;
图8为本发明第八实施例的压电MEMS硅谐振器的剖面示意图；8 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eighth embodiment of the present invention;
图9为本发明第九实施例的压电MEMS硅谐振器的剖面示意图；9 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a ninth embodiment of the present invention;
图10为本发明第十实施例的压电MEMS硅谐振器的剖面示意图；10 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a tenth embodiment of the present invention;
图11为本发明第十一实施例的压电MEMS硅谐振器的剖面示意图；11 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eleventh embodiment of the present invention;
图12为本发明第十二实施例的压电MEMS硅谐振器的剖面示意图；12 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a twelfth embodiment of the present invention;
图13为本发明第十三实施例的压电MEMS硅谐振器的剖面示意图。13 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a thirteenth embodiment of the present invention.
具体实施方式Detailed ways
下面结合实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明的一部分实施例，而并不是全部的实施例。基于本发明中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本发明保护的范围。The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art fall within the protection scope of the present invention.
根据本发明实施方式的压电MEMS硅谐振器，谐振结构具体包括堆叠设置的电极层、压电层和非均匀掺杂的硅温补层，非均匀掺杂的硅温补层包含至少两种不同掺杂浓度，和/或，包含至少两种不同掺杂元素。According to the piezoelectric MEMS silicon resonator according to the embodiment of the present invention, the resonant structure specifically includes stacked electrode layers, piezoelectric layers and a non-uniformly doped silicon temperature compensation layer, and the non-uniformly doped silicon temperature compensation layer includes at least two The different doping concentrations, and/or, contain at least two different doping elements.
其中，非均匀掺杂的硅温补层包含至少两种不同掺杂浓度的情况下，压电层中应力分布情况与硅温补层的掺杂浓度分布情况二者之间满足预设对应规则。其中，器件中的谐振结构可以为悬臂梁、固支梁、简支梁或者振膜等形式。预设对应规则具体可以包括：(1)当谐振结构工作在Lamé拉梅模式，或者当压电层的厚度小于硅温补层厚度的情况下，压电层中应力分布情况与硅温补层的掺杂浓度分布情况二者呈正相关；(2)当谐振结构工作在Lamb兰姆模式或弯曲模式，或者当压电层的厚度大于硅温补层厚度的情况下，压电层中应力分布情况与硅温补层的掺杂浓度分布情况二者呈负相关。其中，“正/负相关”是指：压电层某个局部位置应力越大，则硅温补层对应的局部位置掺杂浓度越高/越低。根据本发明实施方式的压电MEMS硅谐振器，其中谐振结构为沿着第一方向延伸的悬臂梁，悬臂梁包括沿第二方向堆叠的电极层、压电层和非均匀掺杂的硅温补层，其中，第一方向与第二方向互相垂直。Wherein, when the non-uniformly doped silicon temperature compensation layer contains at least two different doping concentrations, the stress distribution in the piezoelectric layer and the doping concentration distribution of the silicon temperature compensation layer satisfy a preset correspondence rule . Wherein, the resonant structure in the device may be in the form of a cantilever beam, a fixed beam, a simply supported beam, or a diaphragm. The preset corresponding rules may specifically include: (1) When the resonant structure works in the Lamé mode, or when the thickness of the piezoelectric layer is less than the thickness of the silicon temperature compensation layer, the stress distribution in the piezoelectric layer is different from the silicon temperature compensation layer. (2) When the resonant structure works in the Lamb mode or bending mode, or when the thickness of the piezoelectric layer is greater than the thickness of the silicon temperature compensation layer, the stress distribution in the piezoelectric layer There is a negative correlation between the situation and the doping concentration distribution of the silicon temperature compensation layer. Wherein, "positive/negative correlation" means that the greater the stress at a certain local position of the piezoelectric layer, the higher/lower the doping concentration at the corresponding local position of the silicon temperature compensation layer. The piezoelectric MEMS silicon resonator according to an embodiment of the present invention, wherein the resonance structure is a cantilever beam extending along a first direction, and the cantilever beam includes an electrode layer, a piezoelectric layer, and a non-uniformly doped silicon temperature stacked along a second direction. The complementary layer, wherein the first direction and the second direction are perpendicular to each other.
需要说明的是，该压电MEMS硅谐振器的具体结构可以灵活设计。例如：压电层-电极层组成的堆叠可以位于硅温补层的垂直上方或者垂直下方或者水平侧方。电极层数量可以为两个，分别设置在压电层两侧；电极层数量也可以为仅一个，将简并掺杂的硅温补层充当另一个电极层，硅温补层与单个电极层构成工作电极对。可以是第一方向为水平方向并且第二方向为垂直方向，也可以是第一方向为水平面中x轴方向并且第二方向为水平面中y轴方向等等。It should be noted that the specific structure of the piezoelectric MEMS silicon resonator can be flexibly designed. For example, the piezoelectric layer-electrode layer stack can be located vertically above or vertically below or horizontally to the side of the silicon temperature compensation layer. The number of electrode layers can be two, which are respectively arranged on both sides of the piezoelectric layer; the number of electrode layers can also be only one, the degenerate doped silicon temperature compensation layer is used as another electrode layer, and the silicon temperature compensation layer is connected with a single electrode layer. constitute the working electrode pair. The first direction may be the horizontal direction and the second direction may be the vertical direction, or the first direction may be the x-axis direction in the horizontal plane and the second direction may be the y-axis direction in the horizontal plane, and so on.
以下以说明书附图中的各部分结构及材料加以说明：The structures and materials of each part in the accompanying drawings are described below:
101：上电极，具体材料可选钼、钌、金、铝、镁、钨、铜，钛、铱、锇、铬或以上金属的复合或其合金。另外，也可以采用非金属导电材料，如掺杂硅等。101: Upper electrode, the specific material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or their alloys. In addition, non-metallic conductive materials, such as doped silicon, can also be used.
102：压电层，可选氮化铝、氧化锌、PZT等材料并包含上述材料的一定原子比的稀土元素掺杂材料。102: Piezoelectric layer, which can be selected from materials such as aluminum nitride, zinc oxide, and PZT, and includes a rare earth element doped material with a certain atomic ratio of the above materials.
103：下电极，同101。下电极为可选结构，当硅温补层为重掺杂或者简并掺杂硅时，其可作为下电极使用。103: Lower electrode, same as 101. The lower electrode is an optional structure. When the silicon temperature compensation layer is heavily doped or degenerately doped silicon, it can be used as the lower electrode.
104：硅温补层，材料可选单晶硅、多晶硅等。其中颜色越深表示掺杂浓度越大。104: Silicon temperature compensation layer, the material can be selected from monocrystalline silicon, polycrystalline silicon, etc. The darker the color, the higher the doping concentration.
105：埋氧层。埋氧层为可选结构，如果不是SOI晶圆加工悬臂梁，也可以无此结构层。105: Buried oxide layer. The buried oxide layer is an optional structure. If it is not a SOI wafer processing cantilever beam, this structure layer can also be omitted.
106：空腔。106: Cavity.
107：基底，材料同104。107: Substrate, the same material as 104.
图1为本发明第一实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，靠近悬臂梁的自由端的第一端面位置(即图示中的左端面)掺杂浓度最高，靠近悬臂梁的固定端的第二端面位置(即图示中的右端面)掺杂浓度最低，掺杂浓度沿着第一方向(即图示中的水平方向)渐变。FIG. 1 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a first embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the doping concentration is the highest at the position of the first end face near the free end of the cantilever beam (ie, the left end face in the figure), and the first end face near the fixed end of the cantilever beam has the highest doping concentration. The position of the two end faces (ie, the right end face in the figure) has the lowest doping concentration, and the doping concentration is graded along the first direction (ie, the horizontal direction in the figure).
具体地，第一实施例中在越靠近悬臂梁自由端位置掺杂浓度高，越靠近悬臂梁固定端掺杂浓度越低。使温度补偿更多的发生在应力、应变小的自由端，而应力、应变大的固定端不需要太高的掺杂浓度，因而避免了高浓度掺杂后由于固定端刚度变化过大导致的谐振频率漂移。即在温度补偿的同时防止了掺杂的负面效应。当高应力区域掺杂导致的频率偏移效应大于热量分布导致的频率偏移效应时，例如当悬臂梁工作在Lamé拉梅模式时，或者当压电层的厚度小于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the first embodiment, the doping concentration is higher at the position closer to the free end of the cantilever beam, and the lower the doping concentration is at the position closer to the fixed end of the cantilever beam. The temperature compensation occurs more at the free end with small stress and strain, and the fixed end with large stress and strain does not need too high doping concentration, thus avoiding the excessive change of the rigidity of the fixed end after high concentration doping. Resonant frequency drift. That is, the negative effects of doping are prevented while compensating for temperature. When the frequency shift effect caused by the doping of the high stress region is larger than that caused by the heat distribution, such as when the cantilever operates in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than that of the silicon temperature compensation layer, The doping method of this embodiment is preferably selected for temperature compensation.
图2为本发明第二实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，靠近悬臂梁的自由端的第一端面位置(即图示中的左端面)掺杂浓度最低，靠近悬臂梁的固定端的第二端面位置(即图示中的右端面)掺杂浓度最高，掺杂浓度沿着第一方向(即图示中的水平方向)渐变。2 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a second embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the doping concentration of the first end face near the free end of the cantilever beam (ie the left end face in the figure) is the lowest, and the doping concentration of the first end face near the fixed end of the cantilever beam is the lowest. The position of the two end faces (ie, the right end face in the figure) has the highest doping concentration, and the doping concentration is graded along the first direction (ie, the horizontal direction in the figure).
具体地，第二实施例中的浓度分布和第一实施例相反。这里考虑了悬臂梁振动产热的热量分布。在固定端由于应力应变较大因而有更多的振动机械能转化为热，因此在固定端温度变化相对更明显。根据各部分温度分布进行相应的温度补偿能够保持各部分谐振频率稳定，避免因为不同部位间谐振频率变化不一致而产生振动模式的改变。当高应力区域掺杂导致的频率偏移效应小于热量分布导致的频率偏移效应时，例如当悬臂梁工作在Lamb兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, the concentration distribution in the second embodiment is opposite to that in the first embodiment. Here, the heat distribution of the cantilever beam vibration heat generation is considered. Due to the larger stress and strain at the fixed end, more vibrational mechanical energy is converted into heat, so the temperature change at the fixed end is relatively more obvious. Corresponding temperature compensation according to the temperature distribution of each part can keep the resonant frequency of each part stable, and avoid the change of vibration mode due to the inconsistent change of resonant frequency between different parts. When the frequency shift effect caused by doping in the high stress region is smaller than that caused by the heat distribution, such as when the cantilever operates in Lamb mode or bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer When the thickness is selected, the doping method of this embodiment is preferably selected for temperature compensation.
图3为本发明第三实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，硅温补层的第一居中切面位置掺杂浓度最低，靠近悬臂梁的自由端的第一端面位置(即图示中的左端面)和靠近所示悬臂梁的固定端的第二端面位置(即图示中的右端面)掺杂浓度最高，掺杂浓度从第一居中切面向第一端面和第二端面分别渐变，其中，第一居中切面与第一端面和第二端面平行并且到二者距离相等。3 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a third embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the doping concentration of the first central tangential plane of the silicon temperature compensation layer is the lowest, and the position of the first end surface close to the free end of the cantilever beam (that is, the The left end face) and the position of the second end face near the fixed end of the cantilever beam shown (that is, the right end face in the figure) have the highest doping concentration, and the doping concentration is graded from the first centering cut to the first end face and the second end face respectively, wherein , the first central tangent plane is parallel to and equidistant from the first and second end faces.
具体地，第三实施例中考虑了固定端应力大产热多的情况因而固定端设计了较高的掺杂浓度。同时为避免了中间位置因掺杂导致刚度变化过大，因而将温度补偿更多的设置在自由端附近。当热量分布导致的频率偏移效应较明显时，例如当悬臂梁工作在兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the third embodiment, the situation that the fixed end has a large stress and generates a lot of heat is considered, so the fixed end is designed with a higher doping concentration. At the same time, in order to avoid the excessive change of stiffness in the middle position due to doping, more temperature compensation is set near the free end. When the frequency shift effect caused by the heat distribution is obvious, for example, when the cantilever beam works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer, the doping of this embodiment is preferred. method for temperature compensation.
图4为本发明第四实施例的压电MEMS硅谐振器的剖面示意图。如 图所示，靠近压电层的第一侧面位置(即图示中的顶表面)掺杂浓度最高，远离压电层的第二侧面位置(即图示中的底表面)掺杂浓度最低，掺杂浓度沿着第二方向(即图示中的垂直方向)渐变。4 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a fourth embodiment of the present invention. As shown in the figure, the doping concentration is the highest at the position near the first side of the piezoelectric layer (ie, the top surface in the figure), and the doping concentration at the second side position far away from the piezoelectric layer (ie, the bottom surface in the figure) is the lowest. , the doping concentration is graded along the second direction (ie, the vertical direction in the figure).
具体地，第四实施例中在振动过程中靠近硅温补层与下电极界面的位置，界面缺陷随着振动往复性滑动产生热能，因而此处温度变化较大，在界面附近可以设计较高的掺杂浓度。当热量分布导致的频率偏移效应较明显时，例如当悬臂梁工作在兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the fourth embodiment, at the position close to the interface between the silicon temperature compensation layer and the lower electrode during the vibration process, the interface defects reciprocally slide with the vibration to generate thermal energy, so the temperature here changes greatly, and a higher temperature can be designed near the interface. doping concentration. When the frequency shift effect caused by the heat distribution is obvious, for example, when the cantilever beam works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer, the doping of this embodiment is preferred. method for temperature compensation.
图5为本发明第五实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，靠近压电层的第一侧面位置(即图示中的顶表面)掺杂浓度最低，远离压电层的第二侧面位置(即图示中的底表面)掺杂浓度最高，掺杂浓度沿着第二方向(即图示中的垂直方向)渐变。5 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a fifth embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the doping concentration near the first side of the piezoelectric layer (that is, the top surface in the figure) is the lowest, and is far from the second side of the piezoelectric layer. The position (ie, the bottom surface in the figure) has the highest doping concentration, and the doping concentration is graded along the second direction (ie, the vertical direction in the figure).
具体地，第五实施例中在考虑应力分布的情况下，硅温补层的底表面较顶表面的应变更大，因而底表面温度变化较大。因此，底表面需要更高的掺杂浓度。当高应力区域掺杂导致的频率偏移效应较明显时，例如当悬臂梁工作在Lamé拉梅模式时，或者当压电层的厚度小于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the fifth embodiment, considering the stress distribution, the strain of the bottom surface of the silicon temperature compensation layer is larger than that of the top surface, so the temperature of the bottom surface varies greatly. Therefore, a higher doping concentration is required for the bottom surface. When the frequency shift effect caused by doping in the high stress region is obvious, for example, when the cantilever beam works in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than the thickness of the silicon temperature compensation layer, the dopant of this embodiment is preferentially selected. Miscellaneous way to perform temperature compensation.
图6为本发明第六实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，硅温补层中，硅温补层的第二居中切面位置掺杂浓度最低，靠近压电层的第一侧面位置(即图示中的顶表面)和远离压电层的第二侧面位置(即图示中的底表面)掺杂浓度最高，掺杂浓度从第二居中切面向第一侧面和第二侧面分别渐变，其中，第二居中切面与第一侧面和第二侧面平行并且到二者距离相等。6 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a sixth embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, in the silicon temperature compensation layer, the doping concentration of the second center section of the silicon temperature compensation layer is the lowest, which is close to the first side position of the piezoelectric layer ( That is, the top surface in the figure) and the second side position away from the piezoelectric layer (that is, the bottom surface in the figure) have the highest doping concentration, and the doping concentration is graded from the second centering cut to the first side and the second side respectively. , wherein the second centering tangent is parallel to and equidistant from the first side and the second side.
具体的，第六实施例中综合考虑了第四实施例和第五实施例的情况， 硅温补层靠近上下两表面的温度变化都较大，因而需要的温度补偿幅度也更大。在第六实施例中靠近硅温补层上下两侧的掺杂浓度较高，而在中间位置浓度较低。当高应力区域掺杂导致的频率偏移效应小于热量分布导致的频率偏移效应时，例如当悬臂梁工作在兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the sixth embodiment, the conditions of the fourth embodiment and the fifth embodiment are comprehensively considered, and the temperature changes of the silicon temperature compensation layer near the upper and lower surfaces are larger, so the required temperature compensation range is also larger. In the sixth embodiment, the doping concentration near the upper and lower sides of the silicon temperature compensation layer is higher, and the concentration is lower at the middle position. When the frequency shift effect caused by the doping of the high stress region is smaller than that caused by the heat distribution, such as when the cantilever operates in Lamb mode or bending mode, or when the thickness of the piezoelectric layer is greater than the thickness of the silicon temperature compensation layer , the doping method of this embodiment is preferentially selected to perform temperature compensation.
图7为本发明第七实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，硅温补层的第二居中切面位置掺杂浓度最高，靠近压电层的第一侧面位置(即图示中的顶表面)和远离压电层的第二侧面位置(即图示中的底表面)掺杂浓度最低，掺杂浓度从第二居中切面向第一侧面和第二侧面分别渐变，其中，第二居中切面与第一侧面和第二侧面平行并且到二者距离相等。7 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a seventh embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the doping concentration is the highest at the second center section of the silicon temperature compensation layer, which is close to the first side position of the piezoelectric layer (that is, the top in the figure). surface) and the second side position away from the piezoelectric layer (that is, the bottom surface in the figure), the doping concentration is the lowest, and the doping concentration is graded from the second center to the first side and the second side respectively, wherein the second center The cut plane is parallel to and equidistant from the first side and the second side.
具体地，第七实施例中为了降低硅温补层应变、应力大的上下两侧因为掺杂而导致的刚度变化。将浓度分布设计为中间高而上下两侧低，使得大应力区刚度变化不明显，从而在兼顾整体温度补偿的同时避免了因掺杂(刚度变化)导致的频率漂移。当高应力区域掺杂导致的频率偏移效应大于热量分布导致的频率偏移效应时，例如当悬臂梁工作在Lamé拉梅模式时，或者当压电层的厚度小于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the seventh embodiment, in order to reduce the strain of the silicon temperature compensation layer, the stiffness of the upper and lower sides where the stress is large is changed due to doping. The concentration distribution is designed to be high in the middle and low on the upper and lower sides, so that the stiffness change in the large stress region is not obvious, thus avoiding the frequency drift caused by doping (stiffness change) while taking into account the overall temperature compensation. When the frequency shift effect caused by the doping of the high stress region is larger than that caused by the heat distribution, such as when the cantilever operates in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than that of the silicon temperature compensation layer, The doping method of this embodiment is preferably selected for temperature compensation.
图8为本发明第八实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，硅温补层的中心点位置掺杂浓度最高，靠近压电层的第一侧面位置(即图示中的顶表面)、远离压电层的第二侧面位置(即图示中的底表面)、靠近悬臂梁的自由端的第一端面位置(即图示中的左端面)以及靠近悬臂梁的固定端的第二端面位置(即图示中的右端面)掺杂浓度最低，掺杂浓度从中心点向周围渐变。8 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eighth embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the center point of the silicon temperature compensation layer has the highest doping concentration, which is close to the first side position of the piezoelectric layer (ie, the top surface in the figure). , the second side position away from the piezoelectric layer (the bottom surface in the illustration), the first end face position close to the free end of the cantilever beam (the left end face in the illustration), and the second end face position close to the fixed end of the cantilever beam (ie the right end face in the figure) the doping concentration is the lowest, and the doping concentration is gradually graded from the center point to the periphery.
具体地，第八实施例中考虑到在大应力区因为掺杂导致刚度变化过大， 进而使谐振频率漂移。在上述实施例中提到，梁的固定端和硅温补层上下两侧为大应力区，因而在此区域掺杂浓度可适当降低，将梁的中心和靠近自由端位置掺杂浓度升高。特别地，对于固直梁，则只有中心位置为高掺杂浓度区域。当高应力区域掺杂导致的频率偏移效应大于热量分布导致的频率偏移效应时，例如当悬臂梁工作在Lamé拉梅模式时，或者当压电层的厚度小于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the eighth embodiment, it is considered that the change in stiffness is too large due to doping in the large stress region, thereby causing the resonant frequency to drift. As mentioned in the above embodiments, the fixed end of the beam and the upper and lower sides of the silicon temperature compensation layer are large stress regions, so the doping concentration in this region can be appropriately reduced, and the doping concentration at the center of the beam and near the free end is increased. . In particular, for a straight beam, only the central position is the region of high doping concentration. When the frequency shift effect caused by the doping of the high stress region is larger than that caused by the heat distribution, such as when the cantilever operates in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than that of the silicon temperature compensation layer, The doping method of this embodiment is preferably selected for temperature compensation.
图9为本发明第九实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，硅温补层的中心点位置掺杂浓度最低，靠近压电层的第一侧面位置(即图示中的顶表面)、远离压电层的第二侧面位置(即图示中的底表面)、靠近悬臂梁的自由端的第一端面位置(即图示中的左端面)以及靠近悬臂梁的固定端的第二端面位置(即图示中的右端面)掺杂浓度最高，掺杂浓度从中心点向周围渐变。9 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a ninth embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the central point of the silicon temperature compensation layer has the lowest doping concentration, which is close to the first side of the piezoelectric layer (ie, the top surface in the figure). , the second side position away from the piezoelectric layer (the bottom surface in the illustration), the first end face position close to the free end of the cantilever beam (the left end face in the illustration), and the second end face position close to the fixed end of the cantilever beam (ie the right end face in the figure) the doping concentration is the highest, and the doping concentration is graded from the center point to the periphery.
具体地，若考虑大应力区温度升高较多时，则第九实施例中掺杂浓度的分布和第八实施例相反。当高应力区域掺杂导致的频率偏移效应小于热量分布导致的频率偏移效应时，例如当悬臂梁工作在兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, if it is considered that the temperature of the large stress region increases more, the distribution of the doping concentration in the ninth embodiment is opposite to that in the eighth embodiment. When the frequency shift effect caused by the doping of the high stress region is smaller than that caused by the heat distribution, such as when the cantilever operates in Lamb mode or bending mode, or when the thickness of the piezoelectric layer is greater than the thickness of the silicon temperature compensation layer , the doping method of this embodiment is preferentially selected to perform temperature compensation.
如背景技术中陈述：单晶硅的频率温度系数会随着掺杂浓度而改变，掺杂类型可以是p型或者n型掺杂，当掺杂浓度很高时(例如大于等于预设阈值时)，可以左右整个谐振器频率温度系数，甚至将频率温度系数由正变负或由负变正。因此，图1至图9所示的多个实施例中，为了更好的实现温补效果，掺杂浓度最高位置的掺杂浓度大于等于10 19cm -3，进一步，掺杂浓度大于等于10 20cm -3。 As stated in the background art: the frequency temperature coefficient of single crystal silicon will change with the doping concentration, the doping type can be p-type or n-type doping, when the doping concentration is very high (for example, when the doping concentration is greater than or equal to a preset threshold ), which can control the frequency temperature coefficient of the entire resonator, and even change the frequency temperature coefficient from positive to negative or from negative to positive. Therefore, in the various embodiments shown in FIGS. 1 to 9 , in order to better achieve the temperature compensation effect, the doping concentration at the highest position of the doping concentration is greater than or equal to 10 19 cm −3 , and further, the doping concentration is greater than or equal to 10 20 cm -3 .
图10为本发明第十实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，仅在第二方向上的居中区域(即在垂直方向的居中区域)具有第一掺杂浓度，其余部位具有第二 掺杂浓度，第一掺杂浓度大于第二掺杂浓度。10 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a tenth embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, only the central region in the second direction (ie, the central region in the vertical direction) has the first doping concentration, and the remaining parts have the second doping concentration impurity concentration, the first doping concentration is greater than the second doping concentration.
具体地，可以只在部分区域进行简并掺杂以达到对特定位置进行温度补偿的目的。优选地，只在硅温补层的中轴面上进行掺杂，由于这一面上没有应变，因而最大限度的避免了因为杂质引入导致的频率变化。当高应力区域掺杂导致的频率偏移效应较明显时，例如当悬臂梁工作在Lamé拉梅模式时，或者当压电层的厚度小于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, degenerate doping can be performed only in part of the region to achieve the purpose of temperature compensation for a specific position. Preferably, doping is performed only on the central axis surface of the silicon temperature compensation layer, since there is no strain on this surface, the frequency change caused by the introduction of impurities is avoided to the greatest extent. When the frequency shift effect caused by doping in the high stress region is obvious, for example, when the cantilever beam works in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than the thickness of the silicon temperature compensation layer, the dopant of this embodiment is preferentially selected. Miscellaneous way to perform temperature compensation.
图11为本发明第十一实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，在第一方向上靠近悬臂梁的固定端的位置具有第一掺杂浓度，其余部位具有第二掺杂浓度，第一掺杂浓度大于第二掺杂浓度。11 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to an eleventh embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the position close to the fixed end of the cantilever beam in the first direction has a first doping concentration, and the other parts have a second doping concentration. The impurity concentration is greater than the second dopant concentration.
具体地，第十一实施例中在固定端由于应力应变较大因而有更多的振动机械能转化为热，因此在固定端温度变化相对更明显。根据各部分温度分布进行相应的温度补偿能够保持各部分谐振频率稳定，避免因为不同部位间谐振频率变化不一致而产生振动模式的改变。当高应力区域掺杂导致的频率偏移效应小于热量分布导致的频率偏移效应时，例如当悬臂梁工作在Lamb兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the eleventh embodiment, due to the larger stress and strain at the fixed end, more vibrational mechanical energy is converted into heat, so the temperature change at the fixed end is relatively more obvious. Corresponding temperature compensation according to the temperature distribution of each part can keep the resonant frequency of each part stable, and avoid the change of vibration mode due to the inconsistent change of resonant frequency between different parts. When the frequency shift effect caused by doping in the high stress region is smaller than that caused by the heat distribution, such as when the cantilever operates in Lamb mode or bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer When the thickness is selected, the doping method of this embodiment is preferably selected for temperature compensation.
图12为本发明第十二实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，在第一方向上靠近悬臂梁的固定端并且在第二方向上的居中的区域(即图示的靠右端并且垂直方向上居中的位置)具有第一掺杂浓度，其余部位具有第二掺杂浓度，第一掺杂浓度大于第二掺杂浓度。12 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a twelfth embodiment of the present invention. As shown in the figure, in the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator, the region close to the fixed end of the cantilever beam in the first direction and the central region in the second direction (that is, the right end and the vertical direction as shown in the figure) The upper center position) has a first doping concentration, and the remaining parts have a second doping concentration, and the first doping concentration is greater than the second doping concentration.
具体地，第十二实施例中只在靠近固定端的中间区域进行掺杂，这一区域是温度变化最明显、应力最大的区域，对这一区域进行温度补偿效果 明显。当热量分布导致的频率偏移效应较明显时，例如当悬臂梁工作在兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the twelfth embodiment, doping is only performed in the middle region near the fixed end, which is the region with the most obvious temperature change and the largest stress, and the effect of temperature compensation on this region is obvious. When the frequency shift effect caused by the heat distribution is obvious, for example, when the cantilever beam works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer, the doping of this embodiment is preferred. method for temperature compensation.
图13为本发明第十三实施例的压电MEMS硅谐振器的剖面示意图。如图所示，该压电MEMS硅谐振器的硅温补层中，在固定端的位置具有第一掺杂浓度，其余部位具有第二掺杂浓度，第一掺杂浓度大于第二掺杂浓度。在靠近悬臂梁的固定端位置掺杂，通过固定端和悬臂梁之间的机械耦合，同样可以实现悬臂梁谐振器的频率温度补偿；同时，由于掺杂位置不在悬臂梁上，这种方式可以避免悬臂梁掺杂带来的负面效应，如Q值降低等。13 is a schematic cross-sectional view of a piezoelectric MEMS silicon resonator according to a thirteenth embodiment of the present invention. As shown in the figure, the silicon temperature compensation layer of the piezoelectric MEMS silicon resonator has a first doping concentration at the position of the fixed end, and a second doping concentration at the other parts, and the first doping concentration is greater than the second doping concentration . Doping at the position close to the fixed end of the cantilever beam can also achieve frequency and temperature compensation of the cantilever beam resonator through the mechanical coupling between the fixed end and the cantilever beam; at the same time, since the doping position is not on the cantilever beam, this method can Avoid negative effects caused by cantilever doping, such as Q reduction.
具体地，第十三实施例中在具有较大大应力的固定区域(此处为固定区域，并非靠近固定端的悬臂梁区域)进行高浓度掺杂，增加载流子浓度即导热速率增加，因而减缓振动产热导致的温漂现象。当热量分布导致的频率偏移效应较明显时，例如当悬臂梁工作在兰姆模式或弯曲模式时，或者当压电层的厚度大于硅温补层厚度时，优先选取本实施例的掺杂方式进行温度补偿。Specifically, in the thirteenth embodiment, high-concentration doping is performed in the fixed region with large stress (here, the fixed region, not the cantilever beam region near the fixed end), increasing the carrier concentration means that the thermal conductivity increases, thus slowing down Temperature drift caused by vibration heat generation. When the frequency shift effect caused by the heat distribution is obvious, for example, when the cantilever beam works in the Lamb mode or the bending mode, or when the thickness of the piezoelectric layer is greater than that of the silicon temperature compensation layer, the doping of this embodiment is preferred. method for temperature compensation.
优选的，图10至图13所示的多个实施例中，为了更好的实现温补效果，第一掺杂浓度大于等于10 19cm -3，进一步，第一掺杂浓度大于等于10 20cm -3。 Preferably, in the embodiments shown in FIGS. 10 to 13 , in order to better achieve the temperature compensation effect, the first doping concentration is greater than or equal to 10 19 cm −3 , and further, the first doping concentration is greater than or equal to 10 20 cm -3 .
本发明实施方式的电子设备，包括本发明公开的任一种压电MEMS硅谐振器。The electronic device according to the embodiment of the present invention includes any piezoelectric MEMS silicon resonator disclosed in the present invention.
根据本发明的技术方案，依据谐振器在谐振状态下的温度分布、应力分布、位移量分布等参数，在谐振器中硅结构中采用不均匀分布掺杂方案，根据不同部位的需要设计相应的掺杂浓度，实现更精准的温度补偿(如各阶频率温度系数的全补偿)。另外，通过浓度分布调节单晶硅刚度的分布， 当其刚度分布与应力、应变或位移场分布达到一定的相互匹配时，谐振器的机电耦合系数将得到提升。According to the technical scheme of the present invention, according to the temperature distribution, stress distribution, displacement distribution and other parameters of the resonator in the resonant state, an unevenly distributed doping scheme is adopted in the silicon structure of the resonator, and the corresponding doping scheme is designed according to the needs of different parts. Doping concentration to achieve more accurate temperature compensation (such as full compensation of the temperature coefficient of each order frequency). In addition, the distribution of the stiffness of the single crystal silicon is adjusted by the concentration distribution. When the stiffness distribution and the stress, strain or displacement field distribution reach a certain mutual match, the electromechanical coupling coefficient of the resonator will be improved.
需要说明的是，以上为考虑一种或两种情况的掺杂浓度分布，也可以同时考虑多种因素进行掺杂浓度的设计。上述具体实施方式，并不构成对本发明保护范围的限制。本领域技术人员应该明白的是，取决于设计要求和其他因素，可以发生各种各样的修改、组合、子组合和替代。任何在本发明的精神和原则之内所作的修改、等同替换和改进等，均应包含在本发明保护范围之内。It should be noted that the above is the doping concentration distribution considering one or both cases, and the doping concentration can also be designed considering multiple factors at the same time. The above-mentioned specific embodiments do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (20)

  1. 一种压电MEMS硅谐振器，其特征在于，器件中的谐振结构包括堆叠设置的电极层、压电层和非均匀掺杂的硅温补层，所述非均匀掺杂的硅温补层包含至少两种不同掺杂浓度，和/或，包含至少两种不同掺杂元素。A piezoelectric MEMS silicon resonator, characterized in that the resonant structure in the device comprises stacked electrode layers, piezoelectric layers and a non-uniformly doped silicon temperature compensation layer, the non-uniformly doped silicon temperature compensation layer At least two different doping concentrations are included, and/or, at least two different doping elements are included.
  2. 根据权利要求1所述的压电MEMS硅谐振器，其特征在于，在所述非均匀掺杂的硅温补层包含至少两种不同掺杂浓度的情况下，所述压电层中应力分布情况与所述硅温补层的掺杂浓度分布情况二者之间满足如下预设对应规则：The piezoelectric MEMS silicon resonator according to claim 1, wherein when the non-uniformly doped silicon temperature compensation layer contains at least two different doping concentrations, the stress distribution in the piezoelectric layer The following preset correspondence rules are satisfied between the situation and the doping concentration distribution of the silicon temperature compensation layer:
    当所述谐振结构工作在Lamé拉梅模式，或者当所述压电层的厚度小于所述硅温补层厚度的情况下，所述压电层中应力分布情况与所述硅温补层的掺杂浓度分布情况二者呈正相关；When the resonant structure works in the Lamé mode, or when the thickness of the piezoelectric layer is smaller than the thickness of the silicon temperature compensation layer, the stress distribution in the piezoelectric layer is different from that of the silicon temperature compensation layer. The doping concentration distribution is positively correlated;
    当所述谐振结构工作在Lamb兰姆模式或弯曲模式，或者当所述压电层的厚度大于所述硅温补层厚度的情况下，所述压电层中应力分布情况与所述硅温补层的掺杂浓度分布情况二者呈负相关。When the resonant structure works in Lamb mode or bending mode, or when the thickness of the piezoelectric layer is greater than the thickness of the silicon temperature compensation layer, the stress distribution in the piezoelectric layer is related to the temperature of the silicon temperature. The doping concentration distribution of the complementary layer is negatively correlated.
  3. 根据权利要求1所述的压电MEMS硅谐振器，其特征在于，所述谐振结构为悬臂梁、固支梁、简支梁或者振膜。The piezoelectric MEMS silicon resonator according to claim 1, wherein the resonance structure is a cantilever beam, a fixed beam, a simply supported beam or a diaphragm.
  4. 根据权利要求1所述的压电MEMS硅谐振器，其特征在于，所述谐振结构为沿着第一方向延伸的悬臂梁，所述悬臂梁包括沿第二方向堆叠的所述电极层、所述压电层和所述非均匀掺杂的硅温补层，其中，所述第一方向与所述第二方向互相垂直。The piezoelectric MEMS silicon resonator according to claim 1, wherein the resonance structure is a cantilever beam extending along a first direction, and the cantilever beam includes the electrode layers stacked along the second direction, the The piezoelectric layer and the non-uniformly doped silicon temperature compensation layer, wherein the first direction and the second direction are perpendicular to each other.
  5. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，靠近所述悬臂梁的自由端的第一端面位置掺杂浓度最高，靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最低，掺杂浓度沿着所述第一方向渐变。The piezoelectric MEMS silicon resonator according to claim 4, wherein in the silicon temperature compensation layer, the doping concentration is the highest at the position of the first end face near the free end of the cantilever beam, and the doping concentration is the highest near the fixed cantilever beam. The position of the second end face of the end has the lowest doping concentration, and the doping concentration is graded along the first direction.
  6. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，靠近所述悬臂梁的自由端的第一端面位置掺杂浓度最低，靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最高，掺杂浓度沿着所述第一方向渐变。The piezoelectric MEMS silicon resonator according to claim 4, wherein in the silicon temperature compensation layer, the doping concentration is the lowest at the position of the first end face near the free end of the cantilever beam, and the doping concentration is the lowest near the fixed cantilever beam. The position of the second end face of the end has the highest doping concentration, and the doping concentration is graded along the first direction.
  7. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，所述硅温补层的第一居中切面位置掺杂浓度最低，靠近所述悬臂梁的自由端的第一端面位置和靠近所示悬臂梁的固定端的第二端面位置掺杂浓度最高，掺杂浓度从所述第一居中切面向所述第一端面和第二端面分别渐变，其中，所述第一居中切面与所述第一端面和第二端面平行并且到二者距离相等。The piezoelectric MEMS silicon resonator according to claim 4, wherein in the silicon temperature compensation layer, the doping concentration is the lowest at the first center tangent plane of the silicon temperature compensation layer, which is close to the free space of the cantilever beam. The first end face position of the end and the second end face position near the fixed end of the shown cantilever beam have the highest doping concentration, and the doping concentration is graded respectively from the first centering tangent to the first end face and the second end face, wherein the said The first central cut plane is parallel to and equidistant from the first and second end faces.
  8. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，靠近所述压电层的第一侧面位置掺杂浓度最高，远离所述压电层的第二侧面位置掺杂浓度最低，掺杂浓度沿着所述第二方向渐变。The piezoelectric MEMS silicon resonator according to claim 4, wherein, in the silicon temperature compensation layer, the doping concentration is the highest at the position near the first side of the piezoelectric layer, and the second side far from the piezoelectric layer has the highest doping concentration. The doping concentration at the two side surfaces is the lowest, and the doping concentration is graded along the second direction.
  9. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，靠近所述压电层的第一侧面位置掺杂浓度最低，远离所述压电层的第二侧面位置掺杂浓度最高，掺杂浓度沿着所述第二方向渐变。The piezoelectric MEMS silicon resonator according to claim 4, characterized in that, in the silicon temperature compensation layer, the doping concentration is the lowest at the position near the first side of the piezoelectric layer, and the second side far from the piezoelectric layer has the lowest doping concentration. The doping concentration at the two side surfaces is the highest, and the doping concentration is graded along the second direction.
  10. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，所述硅温补层的第二居中切面位置掺杂浓度最低，靠近所述压电层的第一侧面位置和远离所述压电层的第二侧面位置掺杂浓度最高，掺杂浓度从所述第二居中切面向所述第一侧面和第二侧面分别渐变，其中，所述第二居中切面与所述第一侧面和第二侧面平行并且到二者距离相等。The piezoelectric MEMS silicon resonator according to claim 4, characterized in that, in the silicon temperature compensation layer, the doping concentration is the lowest at the position of the second mid-section of the silicon temperature compensation layer, and the doping concentration near the piezoelectric layer is the lowest. The doping concentration is the highest at the position of the first side and the position of the second side far away from the piezoelectric layer, and the doping concentration is graded from the second center cut to the first side and the second side respectively, wherein the second The central cut plane is parallel to and equidistant from the first and second sides.
  11. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，所述硅温补层的第二居中切面位置掺杂浓度最高，靠近所述压电层的第一侧面位置和远离所述压电层的第二侧面位置掺杂浓度最 低，掺杂浓度从所述第二居中切面向所述第一侧面和第二侧面分别渐变，其中，所述第二居中切面与所述第一侧面和第二侧面平行并且到二者距离相等。The piezoelectric MEMS silicon resonator according to claim 4, characterized in that, in the silicon temperature compensation layer, the doping concentration is the highest at the position of the second center cut plane of the silicon temperature compensation layer, and the doping concentration near the piezoelectric layer is the highest. The first side position and the second side position far from the piezoelectric layer have the lowest doping concentration, and the doping concentration is graded respectively from the second center tangent to the first side and the second side, wherein the second The central cut plane is parallel to and equidistant from the first and second sides.
  12. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，所述硅温补层的中心点位置掺杂浓度最高，靠近所述压电层的第一侧面位置、远离所述压电层的第二侧面位置、靠近所述悬臂梁的自由端的第一端面位置以及靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最低，掺杂浓度从所述中心点向周围渐变。The piezoelectric MEMS silicon resonator according to claim 4, wherein in the silicon temperature compensation layer, the center point of the silicon temperature compensation layer has the highest doping concentration, and is close to the first part of the piezoelectric layer. The lateral position, the second lateral position away from the piezoelectric layer, the first end face position close to the free end of the cantilever beam, and the second end face position close to the fixed end of the cantilever beam have the lowest doping concentration, and the doping concentration is the lowest. The center point will gradually fade to the surroundings.
  13. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，所述硅温补层的中心点位置掺杂浓度最低，靠近所述压电层的第一侧面位置、远离所述压电层的第二侧面位置、靠近所述悬臂梁的自由端的第一端面位置以及靠近所述悬臂梁的固定端的第二端面位置掺杂浓度最高，掺杂浓度从所述中心点向周围渐变。The piezoelectric MEMS silicon resonator according to claim 4, wherein, in the silicon temperature compensation layer, the doping concentration is the lowest at the center point of the silicon temperature compensation layer, and is close to the first part of the piezoelectric layer. The lateral position, the second lateral position away from the piezoelectric layer, the first end face position close to the free end of the cantilever beam, and the second end face position close to the fixed end of the cantilever beam have the highest doping concentration, and the doping concentration is the highest. The center point will gradually fade to the surroundings.
  14. 根据权利要求5至13中任一项所述的压电MEMS硅谐振器，其特征在于，掺杂浓度最高位置的掺杂浓度大于等于10 19cm -3，或者，大于等于10 20cm -3。 The piezoelectric MEMS silicon resonator according to any one of claims 5 to 13, wherein the doping concentration at the position with the highest doping concentration is greater than or equal to 10 19 cm -3 , or greater than or equal to 10 20 cm -3 .
  15. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，在第二方向上的居中区域具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。The piezoelectric MEMS silicon resonator according to claim 4, wherein, in the silicon temperature compensation layer, a central region in the second direction has a first doping concentration, and other parts have a second doping concentration, The first doping concentration is greater than the second doping concentration.
  16. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，在第一方向上靠近所述悬臂梁的固定端的位置具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。The piezoelectric MEMS silicon resonator according to claim 4, wherein in the silicon temperature compensation layer, a position close to the fixed end of the cantilever beam in the first direction has a first doping concentration, and other parts have a first doping concentration A second doping concentration, the first doping concentration is greater than the second doping concentration.
  17. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所 述从动层中，在第一方向上靠近所述悬臂梁的固定端并且在第二方向上的居中的区域具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。The piezoelectric MEMS silicon resonator according to claim 4, wherein in the driven layer, a region in the first direction close to the fixed end of the cantilever beam and in the center in the second direction has a first A doping concentration, the remaining parts have a second doping concentration, and the first doping concentration is greater than the second doping concentration.
  18. 根据权利要求4所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，在固定位置具有第一掺杂浓度，其余部位具有第二掺杂浓度，所述第一掺杂浓度大于所述第二掺杂浓度。The piezoelectric MEMS silicon resonator according to claim 4, wherein the silicon temperature compensation layer has a first doping concentration at a fixed position, and a second doping concentration at other parts, and the first doping concentration The impurity concentration is greater than the second dopant concentration.
  19. 根据权利要求15至18中任一项所述的压电MEMS硅谐振器，其特征在于，所述硅温补层中，所述第一掺杂浓度掺大于等于10 19cm -3，或者，大于等于10 20cm -3。 The piezoelectric MEMS silicon resonator according to any one of claims 15 to 18, characterized in that, in the silicon temperature compensation layer, the first doping concentration is greater than or equal to 10 19 cm -3 , or, greater than or equal to 10 20 cm -3 .
  20. 一种电子设备，其特征在于，包括权利要求1至19任一项所述的压电MEMS硅谐振器。An electronic device, characterized by comprising the piezoelectric MEMS silicon resonator according to any one of claims 1 to 19.
PCT/CN2021/091099 2021-04-29 2021-04-29 Piezoelectric mems silicon resonator and electronic device WO2022226913A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070120625A1 (en) * 2005-11-30 2007-05-31 Larson John D Iii Film bulk acoustic resonator (FBAR) devices with temperature compensation
CN103053111A (en) * 2010-08-31 2013-04-17 太阳诱电株式会社 Acoustic wave device
CN109802646A (en) * 2018-12-26 2019-05-24 天津大学 Resonator, filter with temperature compensating layer
CN111010131A (en) * 2019-06-06 2020-04-14 天津大学 Bulk acoustic wave resonator with variable doping concentration, filter and electronic device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070120625A1 (en) * 2005-11-30 2007-05-31 Larson John D Iii Film bulk acoustic resonator (FBAR) devices with temperature compensation
CN103053111A (en) * 2010-08-31 2013-04-17 太阳诱电株式会社 Acoustic wave device
CN109802646A (en) * 2018-12-26 2019-05-24 天津大学 Resonator, filter with temperature compensating layer
CN111010131A (en) * 2019-06-06 2020-04-14 天津大学 Bulk acoustic wave resonator with variable doping concentration, filter and electronic device

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