WO2013185417A1 - 半球谐振式微机械陀螺仪及其加工工艺 - Google Patents

半球谐振式微机械陀螺仪及其加工工艺 Download PDF

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WO2013185417A1
WO2013185417A1 PCT/CN2012/080825 CN2012080825W WO2013185417A1 WO 2013185417 A1 WO2013185417 A1 WO 2013185417A1 CN 2012080825 W CN2012080825 W CN 2012080825W WO 2013185417 A1 WO2013185417 A1 WO 2013185417A1
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hemispherical
layer
silicon
electrode
resonant
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PCT/CN2012/080825
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English (en)
French (fr)
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郭述文
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苏州文智芯微系统技术有限公司
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Priority claimed from CN201210231285.0A external-priority patent/CN103528576B/zh
Application filed by 苏州文智芯微系统技术有限公司 filed Critical 苏州文智芯微系统技术有限公司
Priority to US14/408,177 priority Critical patent/US20170038208A1/en
Publication of WO2013185417A1 publication Critical patent/WO2013185417A1/zh
Priority to US15/814,399 priority patent/US10132632B2/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
    • G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
    • G01C19/567—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode
    • G01C19/5691—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially three-dimensional vibrators, e.g. wine glass-type vibrators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes

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  • the invention relates to a hemispherical resonance micromachined gyroscope and a processing technology based on silicon micromachining.
  • Silicon micromachined gyroscope has wide application prospects in the field of inertial measurement because of its small size, low cost, low power consumption, high impact resistance and high reliability.
  • the accuracy of MEMS gyro products is far lower than that of fiber optic gyros and laser gyros, mainly because the sensitivity of most MEMS resonant gyros depends on the amplitude of the gyro, and the noise signal becomes larger as the amplitude increases, which limits the signal noise. Better than the improvement. Due to its low sensitivity, its application area is greatly limited.
  • the traditional hemispherical resonant gyroscope is made of quartz, and its working principle is based on the theory of cup vibration developed by Professor Brian of Cambridge University more than one hundred years ago.
  • the theory states that when the hemispherical cup rotates around the centerline of the cup, its four-wave abdominal vibration pattern will deflect.
  • the signal of the angular acceleration is obtained by detecting the phase change of the deflection vibration pattern.
  • the hemispherical resonator gyro has a very accurate scale factor and satisfactory random drift and bias stability.
  • the gain and scale factor of the gyro are independent of the material, but only a function of the stress wave oscillation mode generated on the thin shell.
  • the hemispherical resonant gyro is recognized by the inertial technology industry as one of the best performing gyro products, and its accuracy is higher than that of fiber optic gyros and laser gyros. In addition, it has the advantages of high resolution, wide measuring range, anti-overload, anti-radiation and anti-interference.
  • the traditional hemispherical resonator gyro is processed by molten quartz, which is difficult to process, high in cost, and has a price of several hundred thousand to one million dollars, so it cannot be widely used.
  • its volume is also large, and the current minimum size diameter also reaches 20 mm. Therefore, the development of a new generation of miniature low-cost hemispherical resonator gyro naturally becomes a new goal of the inertial technology industry.
  • the object of the present invention is to provide a novel MEMS hemispherical resonance gyroscope based on phase detection principle with high precision, small volume and low cost, and a processing technology based on silicon micromachining.
  • an aspect of the present invention provides a hemispherical resonant micromachined gyroscope including a resonant layer including a hemispherical spherical shell, a plurality of silicon spherical electrodes disposed around the hemispherical spherical shell, and a silicon spherical electrode including a driving electrode,
  • the force balance electrode, the signal detection electrode, and the plurality of shield electrodes, the shield electrode separates the drive electrode, the force balance electrode and the signal detection electrode, the shield electrode meets at one point and the junction point is an anchor point of the hemisphere spherical shell, the hemisphere ball
  • the shell forms a plurality of capacitors with a plurality of silicon spherical electrodes surrounding it; the hemispherical spherical shell is made of polysilicon or silicon dioxide or silicon nitride or diamond.
  • the silicon spherical electrodes are 20 or 24, which include 8 shielding electrodes, and the shielding electrodes are evenly distributed in the circumferential direction of the hemispherical spherical shell.
  • the radius of the hemispherical spherical shell is 600-1800 ⁇ m, preferably 800-1200 ⁇ m; the thickness of the hemispherical spherical shell is 0.5-2.5 ⁇ m, preferably 1.5-2.0 ⁇ m.
  • the working resonant mode of the hemispherical spherical shell that is, the lowest resonant mode is a four-wave abdominal mode, and the resonant frequency is 2000-15000 Hz, preferably 6000-8000 Hz.
  • a side of the resonant layer adjacent to the hemispherical spherical shell is bonded with a first capping layer
  • a side of the resonant layer adjacent to the silicon spherical electrode is bonded with a second capping layer
  • the first capping layer is a glass piece or a silicon wafer having a silicon dioxide layer, a second capping layer made of a glass material containing through-hole glass or a silicon material containing through-hole silicon, and a through-hole glass or a through-hole silicon guiding the silicon spherical electrode to a hemispherical resonant micromachined gyroscope The surface of the instrument.
  • Another aspect of the present invention provides a processing technique of the above-described hemispherical resonance type micromachined gyroscope, which comprises the following steps:
  • a layer of silicon dioxide is formed on the inner surface of the hemispherical pit to form a thermal oxide layer, and a hemispherical spherical shell layer is deposited on the outer side of the thermal oxide layer;
  • the hemispherical spherical shell layer is a polysilicon layer or a silicon dioxide layer or nitrogen Silicon layer or diamond film;
  • a silicon spherical electrode surrounding the hemispherical spherical shell layer is etched on the other side of the silicon wafer, and the thermal oxide layer serves as a barrier layer during etching; after etching, the thermal oxide layer is etched away, and the hemispherical spherical shell layer forms a hemispherical sphere The shell is suspended on the anchor point, and the hemispherical spherical shell forms a plurality of capacitors with the plurality of silicon spherical electrodes surrounding the hemispherical spherical shell;
  • a deep trench is formed on the silicon wafer by photolithography and DRIE deep etching to form a silicon spherical electrode, and a V-groove plate is used for etching, and the width of the deep trench is silicon.
  • the thickness of the wafer is proportional.
  • the hemispherical pit is etched by isotropic etching, and the isotropic etching method comprises dry etching and wet etching;
  • the removal of the thermal oxide layer and the polysilicon layer described in the step (3) is performed by mechanical polishing.
  • the thermal oxidation layer is etched away by gaseous hydrofluoric acid.
  • the thickness of the thermal oxide layer is 1-2 ⁇ m.
  • the first capping layer is bonded to the side of the silicon wafer close to the hemispherical spherical shell.
  • the bonding method includes: when the second capping layer is made of glass, using an anodized silicon-glass bonding method, in the second The surface of the capping layer bonded to the resonant layer is provided with a shallow groove, and a getter film layer is deposited in the shallow groove and then bonded; when the second capping layer is made of silicon, silicon is used. Silicon direct bonding.
  • the present invention has the following advantages over the prior art:
  • the sensitivity of the hemispherical resonant micromachined gyroscope of the present invention does not depend on its amplitude, and its driving voltage is low, which can greatly reduce the output noise, and its accuracy can be higher than that of the existing gyroscope products;
  • the hemispherical resonant micromachined gyroscope of the present invention adopts a process based on silicon microfabrication to make it smaller in size, can reduce production cost, and has mass production capacity.
  • FIG. 1 is a schematic view showing the distribution of silicon spherical electrodes of a hemispherical resonator type micromachined gyroscope of the present invention.
  • FIG. 2 is a schematic view showing a shield electrode supporting hemispherical spherical shell of the hemispherical resonant micromachined gyroscope of the present invention.
  • FIG. 3 is a flow chart showing the processing of the hemispherical resonator type micromachined gyroscope of the present invention.
  • FIG. 4 is a window diagram of a hemispherical resonant micromachined gyroscope of the present invention for forming a silicon spherical electrode by etching a deep trench.
  • FIG. 5 is a schematic cross-sectional view showing a silicon wafer of a hemispherical resonant micromachined gyroscope of the present invention.
  • Figure 6 is a schematic view of the hemispherical resonant micromachined gyroscope of the present invention when the second capping layer is not bonded.
  • Figure 7 is a schematic view showing the operation of the hemispherical resonance type micromachined gyroscope of the present invention.
  • Figure 8 is a four-wave belly mode analysis diagram of the hemispherical resonator type micromachined gyroscope of the present invention.
  • Figure 9 is a three-wave belly mode analysis diagram of the hemispherical resonator type micromachined gyroscope of the present invention.
  • Figure 10 is a five-wave belly mode analysis diagram of the hemispherical resonator type micromachined gyroscope of the present invention.
  • Figure 11 is a diagram showing the pendulum resonance mode analysis of the hemispherical resonator type micromachined gyroscope of the present invention.
  • Embodiment 1 A hemispherical resonant micromachined gyroscope comprising a resonant layer 1, a first capping layer 9 and a second capping layer respectively bonded to the two sides of the resonant layer 1. See Figure 1 and Figure 2 for details.
  • the resonant layer 1 includes a hemispherical spherical shell 2 and a plurality of silicon spherical electrodes disposed around the hemispherical spherical shell 2.
  • the hemispherical spherical shell 2 is made of polycrystalline silicon or silicon dioxide or silicon nitride or diamond. In the present embodiment, polycrystalline silicon is used.
  • the silicon spherical electrode is formed by etching a plurality of deep trenches 3 on a silicon wafer, the material of which is highly doped single crystal silicon.
  • the number of silicon spherical electrodes is 20 or 24, and includes a driving electrode 4, a force balancing electrode 5, a signal detecting electrode 6, and a shield electrode 7.
  • shield electrodes 7 which are evenly distributed in the circumferential direction around the hemispherical spherical shell 2, and the shield electrode 7 separates the drive electrode 4 and the force balance electrode 5 from the signal detecting electrode 6, thereby reducing the driving.
  • the coupling coefficient between the electrode 4 and the signal detecting electrode 6 reduces the quadrature error and noise.
  • the shield electrodes 7 meet at one point and the junction is the anchor point of the hemispherical sphere shell 2, so that the shield electrode 7 can function to support the hemispherical sphere shell 2.
  • the hemispherical spherical shell 2 forms a plurality of capacitances with a plurality of silicon spherical electrodes surrounding it.
  • the radius of the hemispherical spherical shell 2 is 600-1800 ⁇ m, preferably 800-1200 ⁇ m; and the hemispherical spherical shell 2 has a thickness of 0.5-2.5 ⁇ m, preferably 1.5-2.0 ⁇ m.
  • the first cover layer 9 is a glass piece or a silicon wafer having a silicon dioxide layer.
  • the second capping layer is made of a glass material containing through-hole glass or silicon containing through-hole silicon, and the through-hole glass or through-hole silicon leads the silicon spherical electrode to the surface of the hemispherical resonant micromachined gyroscope.
  • the above-described hemispherical resonant micromachined gyroscope employs a processing process based on silicon microfabrication technology.
  • the process includes the following steps:
  • a hemispherical pit 10 having a radius of 800-1200 ⁇ m is etched on the silicon wafer by an isotropic etching method (including dry etching and wet etching), and the etching surface is smooth as a mirror;
  • thermal oxide layer 8 having a thickness of about 1-2 ⁇ m is grown on the inner surface of the hemispherical pit 10, the thermal oxide layer 8 is a silicon dioxide layer, and a layer of LPCVD polysilicon is deposited on the outer side of the thermal oxide layer 8. Layer, the hemispherical shell;
  • the deep trench 3 is etched on the other side of the silicon wafer by photolithography and DRIE dry deep etching to form a silicon spherical electrode surrounding the hemispherical spherical shell 2, and the thermal oxide layer is sacrificed to form the resonant layer 1.
  • the thermal oxide layer 8 serves as a barrier layer during etching. Referring to FIG. 4 and FIG. 5, a V-groove lithography plate is used for etching, and the width of the deep trench 3 is proportional to the thickness of the silicon wafer.
  • the thermal oxide layer 8 grown thereon is also spherical, from top to bottom ("upper” and “lower” as shown in FIG. In the upper and lower directions), when etching the deep trench 3, the etching rate is proportional to the window width of the deep trench 3.
  • the thinner silicon wafer may have penetrated and the thicker silicon wafer has not been etched. .
  • the above-described V-groove lithographic plate pattern is employed, that is, the width of the window near the deep groove 3 at the anchor point is narrow, and the width of the deep groove 3 near the edge of the hemispherical spherical shell 2 is wide.
  • the deep groove 3 which is present on the silicon wafer is substantially "V" shaped from the anchor point toward the edge of the hemispherical spherical shell 2.
  • VAPOR gaseous hydrofluoric acid
  • HF atomic layer etching
  • the conventional quartz hemisphere gyroscope adopts a metal coating method, and the transverse cross section between the electrodes is small, and the signal coupling coefficient between each other is also small.
  • the electrode of the hemispherical resonant micromachined gyroscope of the present invention adopts a highly doped single crystal silicon spherical electrode, and has a large transverse section and a large coupling coefficient between each other, which is easy to generate noise interference.
  • the shieldable electrode 7 is added, not only the hemispherical spherical shell 2 but also the noise interference can be minimized;
  • the second capping layer is vacuum bonded to the side of the resonant layer 1 adjacent to the silicon spherical electrode so that the hemispherical spherical shell 2 is completely enclosed in a vacuum.
  • the second capping layer is made of glass or silicon and contains through-hole glass or via silicon, and through-hole silicon or via glass connects the respective silicon spherical electrodes to the surface of the gyroscope.
  • the second capping layer is made of glass
  • an anodic silicon oxide-glass bonding method is adopted, and in order to increase the Q value as much as possible, a shallow groove is formed on the surface of the second capping layer bonded to the resonant layer 1, and A layer of getter film is deposited in the shallow groove and then bonded;
  • the second cap layer is made of silicon
  • the silicon-silicon direct bonding method is adopted, and because of high temperature bonding, the airtightness is good. Therefore, it is not necessary to deposit a getter film layer.
  • Photolithing is performed on the bonded second capping layer, and the metal electrode is sputter deposited and sliced to complete the processing.
  • the hemispherical spherical shell 2 generates a Coriolis effect when the resonator rotates around the central axis, and the vibration wave pattern thereof is precessed in the circumferential relative hemispherical spherical shell 2.
  • the measurement object of the hemispherical resonant gyroscope is actually the measurement of the phase of the resonant mode, which is different from the silicon micromechanical resonant gyroscope which usually measures amplitude.
  • MEMS gyros are based on measuring the amplitude of the resonance, the sensitivity depends on the amplitude, and the noise signal becomes larger as the amplitude increases, which limits the improvement of the signal-to-noise ratio.
  • the sensitivity of the hemispherical resonant gyro does not depend on the amplitude, and the driving voltage can be low, which can greatly reduce the output noise.
  • the accuracy of silicon MEMS hemispherical resonant gyroscopes is therefore one to three orders of magnitude higher than current MEMS comb-toothed gyro products.
  • the resonant mode of the hemispherical spherical shell 2 can be obtained by finite element analysis.
  • Figures 8 to 11 are typical resonant modes including four-wave abdominal resonant mode, three-wave abdominal resonant mode, and five-wave abdominal resonant mode. State and pendulum resonant mode.
  • the working resonant mode of the hemispherical spherical shell 2, that is, the lowest resonant mode is a four-wave abdominal mode, and its resonant frequency is 2000-15000 Hz, preferably 6000-8000 Hz.
  • the operational stability of low-resonance modes is generally more stable than that of higher-order resonant modes.
  • the invention proposes that the silicon hemispherical resonance type gyroscope is fabricated by an isotropic etching process, and the three-dimensional spherical lithography and the bulk silicon manufacturing process, the diameter of the hemispherical spherical shell 2 is about 2 mm or less, and the thickness of the hemispherical spherical shell 2 is obtained. It is 1-2 ⁇ m.
  • the invention proposes that the silicon hemispherical resonance type gyroscope realizes the wafer level packaging by using the MEMS micro-machining technology, has the capability of mass production, can greatly reduce the cost, and retains the high precision of the hemisphere gyro, etc., which may be possible A revolution in the field of inertial technology will make future navigation systems a universal, low-cost navigation system.

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Abstract

一种半球谐振式微机械陀螺仪，包括谐振层（1），该谐振层（1）包括半球球壳（2）和环绕半球球壳（2）设置的多个硅球面电极。该半球球壳（2）采用多晶硅或二氧化硅或氮化硅或金刚石材质，并具有内凹的内表面及与内表面相对的外表面，半球球壳（2）的顶点为其锚点。硅球面电极包括驱动电极（4）、力平衡电极（5）、信号检测电极（6）、屏蔽电极（7），其中屏蔽电极（7）将驱动电极（4）、力平衡电极（5）与信号检测电极(6）分隔开，该半球球壳（2）与环绕其的多个硅球面电极形成多个电容。该半球谐振式微机械陀螺仪采用基于硅微细加工的工艺，其尺寸较小，生产成本较低，具有批量生产能力的同时，其灵敏度不取决于其振幅，驱动电压较低，可大大减小输出噪声，精度可比现有的陀螺仪产品高。

Description

半球谐振式微机械陀螺仪及其加工工艺
技术领域
本发明涉及一种半球谐振微机械陀螺仪及其采用的基于硅微细加工的加工工艺。
背景技术
硅微机械陀螺仪由于具有体积小、成本低、功耗低、抗冲击、可靠性高等优点，在惯性测量领域有着广泛的应用前景。然而目前MEMS陀螺产品的精度远低于光纤陀螺和激光陀螺，主要是因为大多数MEMS谐振式陀螺的灵敏度取决于其振幅的大小，而噪声信号随振幅增加而变大，这就限制了信噪比的改善。由于灵敏度低，因此大大限制了其应用领域。
传统的半球谐振陀螺仪是由石英加工而成，其工作原理是根据一百多年前剑桥大学布瑞安教授关于杯体振动理论研制成功的。该理论指出半球型的杯体绕着杯的中心线旋转时，其四波腹振动图案将发生偏转。通过对偏转振动图样的相位变化的检测从而得到角加速度的信号。半球谐振子陀螺仪具有很精确的比例因子和令人满意的随机漂移及偏置稳定性，陀螺的增益和比例因子与材料无关，而仅仅是薄壳体上产生的应力波振荡模的函数，对外界环境（加速度、振动、温度等）不敏感，甚至不用温度补偿，所以半球谐振陀螺被惯性技术界公认的目前性能最好的陀螺产品之一，其精度比光纤陀螺和激光陀螺还要高，此外其还有分辨率高，测量范围宽，抗过载，抗辐射，抗干扰等优点。
然而，传统的半球谐振陀螺是由融熔石英加工而成，加工难度大，成本高，价格高达几十万到一百万美元，因此无法得到广泛的应用。另外其体积也较大，目前最小尺寸直径也达到20毫米。因此，研制新一代微型低成本半球谐振陀螺自然成为惯性技术界的新的目标。
发明内容
本发明的目的是提供一种精度高、体积小、成本低的基于相位检测原理的新型MEMS半球谐振式陀螺仪及其采用的基于硅微细加工的加工工艺。
为达到上述目的，本发明一方面提供一种半球谐振式微机械陀螺仪，其包括谐振层，谐振层包括半球球壳、环绕半球球壳设置的多个硅球面电极，硅球面电极包括驱动电极、力平衡电极、信号检测电极、多个屏蔽电极，屏蔽电极将驱动电极、力平衡电极与信号检测电极分隔开，屏蔽电极交汇于一点且该交汇点即为半球球壳的锚点，半球球壳与环绕其的多个硅球面电极形成多个电容；半球球壳采用多晶硅或二氧化硅或氮化硅或金刚石材质。
优选的，硅球面电极为20个或24个，其包括8个屏蔽电极，屏蔽电极在半球球壳的周向上均匀分布。
优选的，半球球壳的半径为600-1800μm，优选值为800-1200μm；半球球壳的厚度为0.5-2.5μm，优选值为1.5-2.0μm。
优选的，半球球壳的工作谐振模态，即最低谐振模态为四波腹模态，其谐振频率为2000-15000Hz，优选值为6000-8000Hz。
优选的，谐振层的靠近半球球壳的一侧键合有第一封盖层，谐振层的靠近硅球面电极的一侧键合有第二封盖层；第一封盖层为玻璃片或长有二氧化硅层的硅片，第二封盖层采用含有通孔玻璃的玻璃材质或含有通孔硅的硅材质，通孔玻璃或通孔硅将硅球面电极引到半球谐振式微机械陀螺仪的表面。
本发明另一方面提供一种上述半球谐振式微机械陀螺仪的加工工艺，其包括如下步骤：
（1）在硅晶圆的一面腐蚀一个半球坑；
（2）在半球坑的内表面的生长一层二氧化硅形成热氧化层，再在热氧化层外侧淀积一层半球球壳层；半球球壳层为多晶硅层或二氧化硅层或氮化硅层或金刚石薄膜；
（3）去除半球坑的内表面以外部分的热氧化层及半球球壳层；
（4）在硅晶圆的另一面刻蚀出环绕半球球壳层的硅球面电极，热氧化层作为刻蚀时的阻挡层；刻蚀后腐蚀掉热氧化层，半球球壳层形成半球球壳悬于锚点上，半球球壳与环绕其的多个硅球面电极形成多个电容；
（5）在硅晶圆的表面淀积金属并光刻完成金属化，最终加工形成谐振层。
优选的，步骤（4）中，在硅晶圆上通过光刻及DRIE深度刻蚀法刻蚀出深槽形成硅球面电极，刻蚀时采用V形槽光刻板图，深槽的宽度与硅晶圆的厚度呈正比。
优选的，步骤（1）中，采用各向同性腐蚀法腐蚀出半球坑，各向同性腐蚀法包括干法腐蚀和湿法腐蚀；
步骤（3）中所述的去除热氧化层及多晶硅层采用机械抛光法完成。
步骤（4）中，采用气态氢氟酸腐蚀掉热氧化层。
优选的，热氧化层的厚度为1-2μm。
优选的，去除半球坑的内表面以外部分的热氧化层及半球球壳层后，在硅晶圆的靠近半球球壳的一侧键合第一封盖层。
在硅晶圆的靠近硅球面电极的一侧键合第二封盖层，键合的方法包括：当第二封盖层采用玻璃材质时，采用阳极氧化硅-玻键合方式，在第二封盖层的与谐振层相键合的表面开设浅槽，并在浅槽中淀积一层吸气剂膜层，再进行键合；当第二封盖层采用硅材质时，采用硅-硅直接键合方式。
由于上述技术方案运用，本发明与现有技术相比具有下列优点：
1、本发明的半球谐振式微机械陀螺仪的灵敏度不取决于其振幅，其驱动电压较低，可大大减小输出噪声，其精度可比现有的陀螺仪产品高；
2、本发明的半球谐振式微机械陀螺仪采用基于硅微细加工的工艺，使其尺寸较小，可以降低生产成本，具有批量生产能力。
附图说明
附图1为本发明的半球谐振式微机械陀螺仪的硅球面电极的分布示意图。
附图2为本发明的半球谐振式微机械陀螺仪的屏蔽电极支撑半球球壳的示意图。
附图3为本发明的半球谐振式微机械陀螺仪的加工工艺流程图。
附图4为本发明的半球谐振式微机械陀螺仪通过刻蚀深槽形成硅球面电极的窗口图。
附图5为本发明的半球谐振式微机械陀螺仪的硅晶圆的截面示意图。
附图6为本发明的半球谐振式微机械陀螺仪在未键合第二封盖层时的示意图。
附图7为本发明的半球谐振式微机械陀螺仪的工作原理图。
附图8为本发明的半球谐振式微机械陀螺仪的四波腹模态分析图。
附图9为本发明的半球谐振式微机械陀螺仪的三波腹模态分析图。
附图10为本发明的半球谐振式微机械陀螺仪的五波腹模态分析图。
附图11为本发明的半球谐振式微机械陀螺仪的摆式谐振模态分析图。
以上附图中：1、谐振层；2、半球球壳；3、深槽；4、驱动电极；5、力平衡电极；6、信号检测电极；7、屏蔽电极；8、热氧化层；9、第一封盖层；10、半球坑。
具体实施方式
下面结合附图所示的实施例对本发明作进一步描述。
实施例一：一种半球谐振式微机械陀螺仪，其包括谐振层1、分别键合于谐振层1两侧的第一封盖层9和第二封盖层。参见附图1和附图2所示。
谐振层1包括半球球壳2、环绕半球球壳2设置的多个硅球面电极。半球球壳2采用多晶硅或二氧化硅或氮化硅或金刚石材质，在本实施例中，选用多晶硅。硅球面电极通过在硅晶圆上刻蚀多条深槽3形成，其材料为高掺杂单晶硅。硅球面电极的个数为20个或24个，其包括驱动电极4、力平衡电极5、信号检测电极6、屏蔽电极7。在本实施例中，具有8个屏蔽电极7，其在环绕半球球壳2的周向上均匀分布，屏蔽电极7将驱动电极4、力平衡电极5与信号检测电极6分隔开，从而降低驱动电极4与信号检测电极6之间的耦合系数，降低了正交误差和噪声。屏蔽电极7相交汇于一点且该交汇点为半球球壳2的锚点，这样屏蔽电极7可以起到支撑半球球壳2的作用。半球球壳2与环绕其的多个硅球面电极形成多个电容。半球球壳2的半径为600-1800μm，优选值为800-1200μm；而半球球壳2的厚度为0.5-2.5μm，优选值为1.5-2.0μm。
第一封盖层9为玻璃片或长有二氧化硅层的硅片。第二封盖层采用含有通孔玻璃的玻璃材质或含有通孔硅的硅材质，通孔玻璃或通孔硅将硅球面电极引到半球谐振式微机械陀螺仪的表面。
参见附图3所示，上述半球谐振式微机械陀螺仪采用基于硅微细加工技术的加工工艺。该工艺包括如下步骤：
（1）采用各向同性腐蚀方法（包括干法腐蚀和湿法腐蚀）在硅晶圆片上腐蚀出一个半径为800-1200μm的半球坑10，腐蚀面要光滑如镜；
（2）在半球坑10的内表面的生长一层厚度约为1-2μm的热氧化层8，该热氧化层8为二氧化硅层，再在热氧化层8外侧淀积一层LPCVD多晶硅层，即半球球壳层；
（3）采用机械抛光法去除半球坑10的内表面以外部分具有的热氧化层8及多晶硅层，仅在半球坑10的内表面上保留热氧化层8和多晶硅层；在硅晶圆的靠近多晶硅层的一侧采用阳极氧化法与一块玻璃片进行硅-玻键合，或是与一块长有一层二氧化硅层的硅片直接键合，即键合第一封盖层9；
（4）在硅晶圆的另一侧通过光刻及DRIE干法深度刻蚀法刻蚀出深槽3形成环绕半球球壳2的硅球面电极，并牺牲掉热氧化层形成谐振层1。热氧化层8作为刻蚀时的阻挡层。参见附图4和附图5所示，刻蚀时采用V形槽光刻板图，深槽3的宽度与硅晶圆的厚度呈正比。由于半球坑10的存在使硅晶圆的截面厚度不均，生长于其上的热氧化层8也呈球面，在由上至下（“上”、“下”指如附图4中所示的上、下方向）刻蚀深槽3时，刻蚀速率与深槽3的窗口宽度呈正比，硅晶圆较薄之处可能已经穿透而硅晶圆较厚之处还未刻蚀结束。为了防止这种现象的发生，采用上述V形槽光刻板图，即靠近锚点处深槽3的窗口宽度较窄，而靠近半球球壳2的边缘处深槽3的窗口宽度较宽。这样，在硅晶圆上呈现出的深槽3由锚点向半球球壳2的边缘方向大致呈“V”形。在刻蚀时，靠近锚点位置的刻蚀速率较小，而靠近半球球壳2的边缘处的刻蚀速率较大，这样即可保证刻蚀到达阻挡层的时间接近一致，从而避免刻蚀尚未结束时就已在某些区域出现穿透的现象。硅球面电极刻蚀后，采用气态氢氟酸（VAPOR HF）腐蚀掉热氧化层8，这样半球球壳层形成半球球壳2并悬于锚点上，半球球壳2与环绕其的多个硅球面电极形成多个电容。传统的石英半球陀螺仪采用金属镀膜法，电极之间的横向截面很小，相互之间的信号耦合系数也小。而本发明的半球谐振式微机械陀螺仪的电极采用高掺杂单晶硅球面电极，其横向截面较大，相互之间的耦合系数也较大，容易产生噪声干扰。增加可屏蔽电极7后，不仅可以支撑半球球壳2，还可把噪声干扰降至最低；
（5）在上述做完热氧化层牺牲释放的硅晶圆表面淀积金属并光刻完成金属化最终加工形成谐振层1，参见附图6所示。在谐振层1的靠近硅球面电极的一侧真空键合第二封盖层，使半球球壳2完全封闭于真空中。第二封盖层采用玻璃或硅材质并含有通孔玻璃或通孔硅，通孔硅或通孔玻璃将各个硅球面电极连接到陀螺仪的表面。当第二封盖层采用玻璃材质时，采用阳极氧化硅-玻键合方式，为了尽可能提高Q值，在第二封盖层的与谐振层1相键合的表面开设浅槽，并在浅槽中淀积一层吸气剂膜层，再进行键合；当第二封盖层采用硅材质时，采用硅-硅直接键合方式，由于是高温键合，气密性较好，因此无需淀积吸气剂膜层。在键合完的第二封盖层上光刻打孔，并溅射淀积金属电极，切片，完成加工工艺。
参见附图7至附图11所示。其工作原理为：半球球壳2作为谐振子绕中心轴旋转时产生哥氏效应而使其振动波型在环向相对半球球壳2进动。当半球球壳2绕中心轴转过ϕ角时，振动波型相对半球球壳2反向转过θ角，且有θ=Kϕ，其中K为进动因子。只要精确测出振动波型相对半球球壳2转过的角度θ 就可以测出半球球壳2绕中心轴转过的角度ϕ，对转动角ϕ微分便可求得角速率Ω，Ω＝ｄϕ／ｄｔ。所以半球谐振式陀螺仪的测量对象实际上就是对谐振模态的相位的测量，这不同于通常通过测量振幅的硅微机械谐振式陀螺。目前绝大多数MEMS陀螺是基于测量谐振振幅大小的，其灵敏度取决于振幅的大小，而噪声信号随振幅增加而变大，这就限制了信噪比的改善。而半球谐振陀螺的灵敏度不取决于振幅，驱动电压可以很低，这样可以大大减小输出噪声。硅MEMS半球谐振陀螺仪精度因此比目前的MEMS梳齿式陀螺产品提高一至三个数量级。
半球球壳2的谐振模态可通过有限元分析得到，附图8至附图11是典型的几个谐振模态，包括四波腹谐振模态、三波腹谐振模态、五波腹谐振模态以及摆式谐振模态。上述半球球壳2的工作谐振模态，即最低谐振模态为四波腹模态，其谐振频率为2000-15000Hz，优选值为6000-8000Hz。低谐振模态的工作稳定性通常比高次谐振模态更稳定。
本发明提出硅半球谐振式陀螺仪是采用各向同性腐蚀工艺制作，再加上三维球面光刻和体硅制作工艺，半球球壳2的直径在2mm左右或更小，半球球壳2的厚度为1-2μm。本发明提出硅半球谐振式陀螺仪由于采用的是MEMS微细加工技术，实现了晶圆级封装，具有批量生产的能力，可以大大降低成本，并保留了半球陀螺高精度等优点，其将有可能在惯性技术领域带来的一场革命，将使得未来的导航系统成为通用的、低价的导航系统。
上述实施例只为说明本发明的技术构思及特点，其目的在于让熟悉此项技术的人士能够了解本发明的内容并据以实施，并不能以此限制本发明的保护范围。凡根据本发明精神实质所作的等效变化或修饰，都应涵盖在本发明的保护范围之内。

Claims (14)

1. 一种半球谐振式微机械陀螺仪，包括谐振层，所述的谐振层包括：
半球球壳，其材质为多晶硅或二氧化硅或氮化硅或金刚石；
环绕半球球壳设置的多个硅球面电极，所述的硅球面电极包括驱动电极、力平衡电极、信号检测电极、多个屏蔽电极，所述的屏蔽电极将驱动电极、力平衡电极与信号检测电极分隔开，屏蔽电极交汇于一点且该交汇点即为半球球壳的锚点，半球球壳与多个硅球面电极形成多个电容。
2. 根据权利要求1所述的半球谐振式微机械陀螺仪，其中，硅球面电极为20个或24个，包括8个屏蔽电极，屏蔽电极沿半球球壳的一截面圆周均匀分布。
3. 根据权利要求1或2所述的半球谐振式微机械陀螺仪，其中，半球球壳的半径为600-1800μm，优选为800-1200μm。
4. 根据权利要求1或2所述的半球谐振式微机械陀螺仪，其中，半球球壳的厚度为0.5-2.5μm，优选为1.5-2.0μm。
5. 根据权利要求1或2所述的半球谐振式微机械陀螺仪，其中，半球球壳的工作谐振模态，即最低谐振模态为四波腹模态，其谐振频率为2000-15000Hz，优选值为6000-8000Hz。
6. 根据权利要求1或2所述的半球谐振式微机械陀螺仪，其中，谐振层的两侧分别键合有第一封盖层和第二封盖层，第一封盖层靠近半球球壳，所述第一封盖层为玻璃片或长有二氧化硅层的硅片，第二封盖层靠近硅球面电极，第二封盖层采用含有通孔玻璃的玻璃材质或含有通孔硅的硅材质，通孔玻璃或通孔硅将硅球面电极引到半球谐振式微机械陀螺仪的表面。
7. 一种如权利要求1所述的半球谐振式微机械陀螺仪的加工工艺，包括如下步骤：
（1）在硅晶圆的一面腐蚀一个半球坑；
（2）在半球坑的内表面生长一层二氧化硅形成热氧化层，再在所述的热氧化层外侧淀积一层半球球壳层，所述的半球球壳层为多晶硅层或二氧化硅层或氮化硅层或金刚石薄膜；
（3）去除半球坑的内表面以外部分的热氧化层及半球球壳层；
（4）在硅晶圆的另一面刻蚀出环绕半球球壳层的硅球面电极，热氧化层作为刻蚀时的阻挡层，刻蚀后腐蚀掉热氧化层，半球球壳层形成半球球壳悬于锚点上，半球球壳与所述的多个硅球面电极形成多个电容；
（5）在硅晶圆的表面淀积金属并光刻完成金属化，最终加工形成谐振层。
8. 根据权利要求7所述的半球谐振式微机械陀螺仪的加工工艺，其中，步骤（4）中，在硅晶圆上通过光刻及DRIE深度刻蚀法刻蚀出深槽形成硅球面电极，刻蚀时采用V形槽光刻板图，深槽的宽度与硅晶圆的厚度呈正比。
9. 根据权利要求7或8所述的半球谐振式微机械陀螺仪的加工工艺，其中，步骤（1）中，采用各向同性腐蚀法腐蚀出半球坑，各向同性腐蚀法包括干法腐蚀和湿法腐蚀。
10. 根据权利要求7或8所述的半球谐振式微机械陀螺仪的加工工艺，其中，步骤（3）中所述的去除热氧化层及多晶硅层采用机械抛光法完成。
11. 根据权利要求7或8所述的半球谐振式微机械陀螺仪的加工工艺，其中，步骤（4）中，采用气态氢氟酸腐蚀掉热氧化层。
12. 根据权利要求7或8所述的半球谐振式微机械陀螺仪的加工工艺，其中，热氧化层的厚度为1-2μm。
13. 根据权利要求7或8所述的半球谐振式微机械陀螺仪的加工工艺，其中，在步骤（3）中所述的去除半球坑的内表面以外部分的热氧化层及半球球壳层后，在硅晶圆的靠近半球球壳的一侧键合第一封盖层。
14. 根据权利要求7或8所述的半球谐振式微机械陀螺仪的加工工艺，其中，在硅晶圆的靠近硅球面电极的一侧键合第二封盖层，键合方式为：当所述的第二封盖层采用玻璃材质时，采用阳极氧化硅-玻键合方式，在第二封盖层的与谐振层相键合的表面开设浅槽，并在浅槽中淀积一层吸气剂膜层，再进行键合；当第二封盖层采用硅材质时，采用硅-硅直接键合方式。
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US10393525B2 (en) 2015-05-22 2019-08-27 Georgia Tech Research Corporation Micro-hemispherical resonators and methods of making the same
CN104913773A (zh) * 2015-05-29 2015-09-16 上海交通大学 半球形微陀螺封装结构及其制备方法
CN109115243A (zh) * 2018-09-20 2019-01-01 北方电子研究院安徽有限公司 基于离子注入的球面电极微半球谐振陀螺仪的制备方法
CN109115243B (zh) * 2018-09-20 2021-06-25 北方电子研究院安徽有限公司 基于离子注入的球面电极微半球谐振陀螺仪的制备方法
CN114562989A (zh) * 2021-12-09 2022-05-31 华中光电技术研究所（中国船舶重工集团公司第七一七研究所） 一种基于光胶连接方式的半球谐振陀螺

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