KR101371149B1 - MEMS Based Gyroscope - Google Patents

Abstract

The present invention provides a highly productive MEMs-based gyroscope that drives in a vertical or lateral direction with respect to a wafer substrate and senses in a vertical or lateral direction. gyroscope, and a frame disposed parallel to the bottom wafer substrate; and, in an excitation mode, the frame is excited with one degree of freedom, and in a sensing mode, when an external angular velocity is input to the frame by a Coriolis force. A sensor mass detected at two degrees of freedom; and at least two sensing electrodes measuring each sensing displacement of two degrees of freedom by the sensor mass; And at least two sensor mass support springs connecting the sensor mass and the frame and allowing the sensor mass to have respective sensing displacements of two degrees of freedom.

Description

MEMS Based Gyroscope

The present invention uses the principle of driving in a vertical or lateral direction with respect to a bottom wafer substrate and sensing in a vertical or lateral direction, The manufacturing process is simple, and robust to microfabrication process and vacuum packaging process error (robust for micro fabrication and for vacuum packaging process error) relates to a high productivity MEMs-based gyroscope.

MEMS (micro electro-mechanical system) gyroscope is a sensor (angular velocity sensor) for measuring the angular velocity of a moving object in three-dimensional space, the degree of freedom (DOF) horizontal vibration system as shown in FIG. And a z-axis gyroscope configured as a 1 degree of freedom horizontal sensing system, or an xy axis gyroscope configured as a degree of freedom horizontal sensing system and a degree of freedom vertical sensing system as shown in FIG. 2.

Inside the MEMs-based gyroscope, there is a vibrating sensor proof mass, and when an angular velocity is applied around an axis (z or y) perpendicular to the direction of excitation (x) from the outside, the sensor mass The Coriolis force (Fc = 2mΩωAsinωt) acts in the third direction (y, or z) perpendicular to the plane formed by the direction (x) and its vertical axis (z, or y). Detect the size of the action. Where m is the mass of the sensor, Ω is the external angular velocity, ω (= 2πf) is the driving frequency for the sensor (i.e. mass + support spring), and A is For driving amplitude, and t is time. The performance sensitivity of MEMs-based gyroscopes is defined as the Coriolis force (Fc / Ω = 2πmfA) relative to the unit angular velocity, so that the mass m of the sensor at the design stage, or the excitation frequency f for the sensor, Alternatively, the excitation amplitude A must be increased.

In the conventional z-axis gyroscope as shown in FIG. 1 or the xy-axis gyroscope as shown in FIG. 2, the maximum driving peak amplitude A of the sensor is equal to the driving resonance frequency of the frequency response curve as shown in FIG. 3. As such, the driving frequency f for the sensor must match the resonance frequency fd of the sensor (f = fd). The sensing peak amplitude As of the sensor is the degree of frequency matching (fs ~ fd) that approximates how close the excited resonance frequency fd for the sensor is to the sensing resonance frequency fs of the sensor. Is determined by At this time, in order to electrically deform parasitic capacitance caused by the excitation voltage from the sensor output signal, fd must not coincide with fs (ie, fd ≠ fs).

Also, as shown in FIG. 3, the sensor excitation amplitude Ad is increased in proportion to the maximum amplitude factor Qd (Quality factor) for the static deformation of the mechanical excitation system, and the sensor detection amplitude As is the maximum amplitude ratio Qs for the static deformation of the mechanical detection system. It also increases in proportion to the quality factor, so it is operated after a hermetic sealing in vacuum environment for mechanical excitation / detection systems such as frames and sensors to increase these Qd or Qs simultaneously.

On the other hand, the magnitude of the movement of the sensor mass caused by the Coriolis force is calculated by measuring the variation of the electrical capacitance C (Capacitance) between the sensor mass and the fixed sensing electrode. In the sensing signal output from the fixed sensing electrode, the parasitic capacitance generated by the excitation voltage relatively higher than the sensing signal is inevitable.

Thus, the overall sensitivity of the gyroscope sensor, as shown in Fig. 1 (z-axis gyroscope) and Fig. 2 (xy-axis gyroscope), in which the excitation and detection systems each have one degree of freedom, as shown in Fig. 3, first, with respect to the sensor mass. Three parameters, namely the degree of frequency matching with the resonant frequency fd with the sensed resonant frequency fs, and the second, the maximum amplitude ratio Q for each of the excitation and sensing systems, and thirdly, the sensor's output signal. It is determined by the ratio between the noise by the parasitic capacitance and the signal to noise ratio (SNR).

In conclusion, as the excitation frequency fd of the sensor is closely matched to the detection resonance frequency fs, the overall sensitivity to the angular velocity can be maximized. However, attempting to approach fd near fs to obtain the maximum possible detection amplitude As is a problem in which the resonant frequencies fd with the sensing resonant frequencies fs are very sensitive to each other due to microfabrication process errors for MEMs-based gyroscope structures. As a result, the deviation of the sense amplitude As for the individual chips in the wafer during the manufacturing process increases, which in turn causes a significant drop in production yield.

Cenk Acar considers that the process error occurring in the micromachining step for the MEMS structure is inevitable, and as shown in FIG. 4, one sensor m is disposed in the xy plane with respect to the z-axis gyroscope. And the second mass (m₂) are separated into two degrees of freedom sensing mode with two sensing resonance frequencies (fs), and one excitation resonance frequency (fd) is flat between two sensing resonance frequencies (fs₁, fs₂). By designing to be in the flat region, a method of preventing a deviation from the flat region even though the resonant frequency or sensed resonant frequency due to a process error occurs is slightly changed (US 7,284,430).

C. The invention of Acar can be implemented in the form of a z-axis gyroscope by arranging a double horizontal sensing decoupled spring inside and outside the horizontal sensor. The gyroscope has a problem that it is very difficult to implement a plurality of vertical sensing non-coupled coupling springs inside and outside the sensor.

On the other hand, in the conventional xy-axis gyroscope as shown in FIG. 2, when the frame is horizontally moved in the x-axis direction in order to maintain the excitation amplitude A large, and the Coriolis force acts in the vertical direction (z) with respect to the bottom wafer substrate, the bottom wafer surface Using this as a sensing electrode, vertical change of sensor mass is detected. This detection method has the following disadvantages. First, it is very difficult to form a uniformly spaced electrode at a certain distance between the surface of the bottom wafer substrate and the sensor mass. Second, the parasitic capacitance is present between the sensing electrode on the bottom wafer substrate and the bottom wafer substrate. It becomes smaller, which reduces the performance sensitivity of the gyroscope.

Recently, Steven S. Nasiri, in the xy-axis gyroscope of Figure 2, integrates the excitation circuitry and sensing circuitry on the bottom wafer surface, and then applies a gyro wafer and cap wafer and wafer level vacuum packaging on it. An xy axis gyroscope with a link spring structure and a method of manufacturing the same have been invented (US 7,621,183; US 6,939,473). However, this technology stacks up to three wafers in sequence, which makes the process very complicated. In addition, low-yielding MEMS is integrated into a System on Chip (SoC) on high-yield CMOS integrated circuits, resulting in low overall yields and high manufacturing costs. The disadvantage is that you have to have.

Therefore, MEMs-based gyroscope structures and manufacturing techniques with high production yields are required. For xy-axis gyroscopes, any design or influence to reduce the origin of process errors for micromachining and vacuum packages from the design stage itself, or their effects No design has yet been realized to reduce this.

US 7,284,430; US 7,621,183; US6,939,473; US5,747,690; US5,349,855; US5,757,103; US6,067,858; US6,122,961; US 7,340,956; US8,035,176; US2002 / 0020219

The present invention has been devised in view of the above problems,

The first object of the present invention is designed to enable linear and rotational vibration for one sensor mass connected to a frame, so that the sensor is separated into two or more sensing resonance modes in close proximity to each other, and two or more sensing resonances in which the resonance frequencies of the sensors are close to each other. By always being placed between frequencies, MEMS xy-axis gyroscopes or z-axis gyroscopes are resistant to microfabrication manufacturing errors without separating the sensor mass into two.

Another second object of the present invention is to eliminate the parasitic capacitance inevitably generated when the bottom electrode of the wafer substrate is used as the sensor mass sensing electrode in a manner that the sensor has a vertical position with respect to the bottom wafer substrate and horizontally senses the sensor mass behavior. It is to provide an xy-axis gyroscope with an improved noise ratio (SNR).

Another third object of the present invention is to provide a MEMS xy-axis gyroscope or z-axis gyroscope that is robust to microfabrication process errors by designing the MEMs basic structures constituting one gyroscope in the same microfabrication process environment. do.

Another fourth object of the present invention is a MEMS xy-axis gyroscope or z-axis gyroscope that is robust to vacuum package processing errors by designing each individual gyroscope chip to be placed in the same vacuum package processing environment throughout one gyro wafer. To provide.

Another fifth object of the present invention is to implement the wiring between the inside and outside of the gyroscope by applying an interconnection method by a silicon through electrode (tsv), thereby producing a batch process from manufacturing to inspection to final package stage. MEMS xy-axis gyroscopes or z-axis gyroscopes are available.

In order to achieve the first object, the present invention proposes a special type of spring and the sensing electrode to which the linear sensing mode and the rotation sensing mode are simultaneously applied to one sensor mass. By such a configuration, the xy-axis gyroscope in the form of vertical driving or horizontal sensing as shown in FIG. 6 or the xy-axis gyroscope in the form of lateral driving vertical sensing, or FIG. A z-axis gyroscope in the form of lateral driving and lateral sensing may be implemented.

In order to achieve the above second object, the present invention proposes an x-y axis gyroscope configured to vertically frame the frame in the z direction and detect horizontal vibration of the sensor mass on the x-y plane as shown in FIG. 6. At this time, in order to have the frame 10 vertically, an n electrode or a p electrode doped with boron or phosphorus is formed in a predetermined region on the bottom substrate 60 to form the bottom electrodes 21, 22, 23, and 24. The gyroscope MEMs structure uses a SOI wafer with a simple microfabrication process with a bottom electrode doped with n or p on the substrate, and the overall package process involves bonding two SOI wafers and a cap wafer first to a gyroscope chip. After fabrication, the SiP (System-in-Package) method can be used.

In addition, in order to achieve the first object and the second object at the same time, in the first embodiment of the present invention, as shown in Figs. 8 and 12, it is applied through the bottom electrode 21, 23 of the bottom wafer 60 A torsional vibration caused by the antiphase electrostatic force, which inevitably includes a frame 10 having one pair of antiphase vertical velocity components, and a non-coupled structure with the frame 10 on the xy plane. Two sensor masses 30 and 32 connected to each other; When the angular velocity is input about one axis y on the xy plane to the frame 10, the sensor masses 30 and 32 are subjected to antiphase Coriolis forces in the direction of another axis x perpendicular to the axis y. Each support spring 36 which connects the sensor masses 30 and 32 to the frame 10 at four points 36a, 36b, 38a and 38b separated by a predetermined distance from the left and right on the x-axis so as to operate in opposite directions. , 38) and; Sensing electrodes 41a, 42a, 43a, 44a, which are arranged separately from left, right, up and down from the center of each sensor mass for sensing the linear vibrations of the respective sensor masses 30 and 32 and the respective movement displacements for the rotational vibrations, or An xy-axis gyroscope configured to include sensing electrodes 45a, 46a, 47a, and 48a, respectively.

In addition, in the second embodiment of the present invention, the sensor mass 30 and the sensor mass 32 are configured to operate in the z-axis direction while keeping parallel to the xy plane, respectively, and are twice as high as Coriolis force as compared with the first embodiment. We propose an xy-axis gyroscope that receives And, according to the second embodiment, a single axis gyroscope on the xy plane consisting of two independent frames and two sensor masses, and another two independent ones of the same size and shape as the single axis gyroscope When the single axis gyroscope on the xy plane, which consists of two frames and two sensor masses, is arranged in parallel with each other, it becomes a Memes-based two-axis gyroscope that can measure the angular velocity about two axes (xy axis) on the xy plane.

In the present invention, in order to achieve the third object, first, as shown in Fig. 16, the frame 10, the support springs 12, 14, 16, the sensor masses 31, 33, and the support spring 36 (38) Resonance frequency fd and sensing resonance frequency fs each composed of beam and hole having the same width and depth with respect to the gyro basic components Offer to desensitize. Because, as shown in Fig. 14, the resonance frequency for the one degree of freedom mode is fd = (1 / 2π) sqrt [Ktd / Jd], and in Fig. 15, the resonance frequency for the one degree of freedom detection mode is fs =. Since (1 / 2π) sqrt [Ks / Ms], each parameter between Ktd (frame torsional stiffness) and Jd (frame mass inertia moment), or Ks (sensor bending stiffness) and Ms (sensor mass) This is because the beam width and thickness of each spring and the ratio of the length of the beam and the etching hole constituting the frame and the sensor mass have a great influence on the resonance frequency.

Next, while using the gyro basic components of FIG. 16 as they are, as shown in FIG. 17, the beam widths and thicknesses of the frame 10 and the sensors 30 and 32 are equal to each other, and the frame support springs. It is proposed to arrange the beams 12, 14 and 16 of the beams and the beams 36a, 36b, 38a, and 38b of the sensor mass support springs in parallel with each other, and to add dummy springs 13 and 17 to the side of each support spring. do. By doing so, even if the two resonant frequencies are changed to maintain the same interval so as to have the same process error dependence each other.

In the present invention, in order to achieve the fourth object, as shown in Fig. 23, the air through hole through which the cap wafer 80 is completely drilled from the front side to the back side outside the vacuum sealing wall. hole) (83). By doing so, the vacuum processing conditions of the individual gyroscope chips for the entire wafer are uniform in the wafer level hermetic sealing step in the vacuum chamber for the SOI MEMS wafer 70 and the cap wafer 80. To be maintained. This keeps the chip-to-chip deviation of the maximum amplitude ratio Q value in each excitation / detection mode to a minimum.

In the present invention, in order to achieve the fifth object, as shown in FIGS. 22 and 23, after the wafer-to-wafer sealing (60, 70, 80) process, the back surface of the bottom wafer 60 and the bottom wafer front doping. Silicon through electrodes 21b, 22b, 23b, 24b for interconnection between the electrodes 21, 22, 23, 24; It is proposed to fabricate the silicon through electrodes 26b, 41b, 42b, 43b, 44b, 45b, 46b, 47b, 48b, respectively, for wiring connection between the bottom surface of the bottom wafer 60 and the MEMS SOI wafer 70 structure.

On the other hand, since the thickness of the bottom wafer 60 becomes thin so as to penetrate through silicon via (TSV; Through Silcon Via), as shown in FIG. 23, the vibration energy having the vertical vibration with respect to the frame 10 is transferred to the bottom wafer substrate 60 and the cap. In order to disperse the wafers 80, pillars 78 and 79 for bonding to the frame wafers 25 and 26 fixed to the bottom wafer substrate 60 are attached to the cap wafer 80 for the protection of the MEM structure. It may further include.

MEMS-based x-y or z-axis gyroscope according to the present invention,

First, because the designed resonant frequency (fd) for the sensor mass (30, 32) with one mass is designed to be in the frequency band between the two sensed resonance frequencies (fs₁, fs₂), micro machining process error for the gyro structure Nevertheless, the proximity Δfs between the resonant frequency and the sensed resonance frequency is maintained almost intact, so that there is almost no change in the sensed amplitude As of the sensor masses 30 and 32.

Second, the bottom electrode on the wafer substrate is used to vertically frame the frame 10, and the horizontal electrode is used to detect the linear and rotational vibrations of the sensor masses 30 and 32 to detect the wafer substrate electrodes 21 and 23. When using as an electrode, the problem that the signal-to-noise ratio (SNR) due to parasitic capacitance inevitably occurs can be improved. This method has a disadvantage in that the amplitude A of the sensor masses 30 and 32 becomes small due to the limitation of the geometric gap between the bottom wafer 60 and the gyro wafer 70, but this disadvantage is caused by increasing the excitation frequency. A solution is possible.

Third, the frame support springs 14 and 16 and the sensor mass body support springs 36 and 38 were arranged in parallel, and all beam widths and beam thicknesses were configured to be the same, and the frame 10 and the sensor mass bodies 30 and 32 were also arranged in parallel. ) Each plate is composed of beams of the same size and holes of the same size as the beam width of each support spring, so that despite the occurrence of micro-processing process error for the gyro structure, the excitation frequency and the detection of the sensor mass (30, 32) The proximity Δfs between the resonant frequencies is maintained as it is, and there is no change in the sensed amplitude As of the sensor masses 30 and 32.

Fourth, since the wafer wafer was sealed in the vacuum chamber by using the cap wafer 80 with the air through-hole 83 drilled on each individual gyro chip, the vacuum of the individual gyroscope chips is maintained almost uniform. As a result, the maximum amplitude ratio Q value in the sensor mass body 30 and 32 sensing mode was not changed.

Finally, not only the SOI wafer with a simple microfabrication process was used as the MEMS structure, but also the wiring between the inside and outside of the gyroscope using the tsv interconnection method by the silicon through electrode. It is possible to automate by batch process from manufacturing to inspection and final package stage, and the overall manufacturing cost is low.

1 is a view showing the operation principle of the z-axis gyroscope of the conventional one degree of freedom horizontal sensing mode having one degree of freedom.
2 is a view showing the operation principle of the xy-axis gyroscope of the conventional 1 degree of freedom horizontal sensing 1 degree of freedom vertical sensing mode.
FIG. 3 shows a frequency response curve for a z-axis gyroscope in a conventional 1 degree of freedom horizontal sensing mode and a xy axis gyroscope in a conventional 1 degree of freedom horizontal sensing mode. to be.
4 is a view showing the operation principle of the z-axis gyroscope in the conventional two degree of freedom horizontal sensing mode with one degree of freedom.
5 is a view showing the operation principle of the z-axis gyroscope of the two degrees of freedom horizontal sensing mode having a degree of freedom of the present invention.
6 is a view showing the operating principle of the xy-axis gyroscope of the two degrees of freedom horizontal sensing mode with one degree of freedom vertical.
FIG. 7 is a diagram illustrating a frequency response curve of an xy-axis gyroscope in a single degree of freedom vertical sensing two degree of freedom horizontal sensing mode of the present invention as shown in FIG. 6.
FIG. 8 is a view schematically showing a horizontal sensing xy-axis gyroscope plane with a vertical according to an embodiment of the present invention.
FIG. 9 schematically shows the frame 10 and support springs 12, 14, 16 in the xy-axis gyroscope of FIG. 8.
FIG. 10 is a view schematically showing the sensor masses 30 and 32, the support springs 36 and 38, and the sensing electrode in the xy-axis gyroscope of FIG.
FIG. 11 is a schematic cross-sectional view taken along line AA ′ of the xy-axis gyroscope of FIG. 8.
12 and 13 are diagrams schematically showing a state in which the forms of FIG. 11 move in operation.
14 is a schematic diagram of a mathematical model of the frame 10 and the support springs 12, 14, 16 in an xy-axis gyroscope according to an embodiment of the present invention.
FIG. 15 is a schematic diagram illustrating a mathematical model of sensor masses 30 and 32 and support springs 36a, 36b, 38a and 38b in an xy-axis gyroscope according to an exemplary embodiment of the present invention.
FIG. 16 is a schematic view of the frame 10 and the sensor masses 30 and 32 including an etching holl in the xy-axis gyroscope of FIG. 8.
FIG. 17 is a view schematically showing dummy beam springs 13 and 17 additionally attached to the frame support springs 14 and 16 in the xy-axis gyroscope of FIG. 8.
18 is a resonance frequency of a process mass of beam mass support springs 36 and 38 with respect to the xy-axis gyroscope according to an exemplary embodiment of the present invention in the case of the 1 degree of freedom and 1 degree of freedom horizontal sensing mode. And simulation results for the change in the sensed resonance frequency.
FIG. 19 illustrates resonance of an xy-axis gyroscope according to an embodiment of the present invention having a process error of the beam widths of the frame support springs 12, 14, and 16 in the case of the 1 degree of freedom and the 1 degree of freedom horizontal sensing mode. Simulation results for changes in frequency and sense resonant frequency.
FIG. 20 is a simulation result of the resonant frequencies and the sensed resonance frequencies of the sensor masses 30 and 32 according to the positional changes of the sensor springs 36 and 38 in FIGS. 14 and 15.
FIG. 21 shows the frame support springs 12, 14, 16, the sensor mass support springs 36, 38, the frame 10, and the sensor mass bodies 30, 32 in FIGS. 14 and 15. 16 and 17, it is a simulation result showing the excitation resonant frequency of the sensor masses 30 and 32 and the change in the sensed resonance frequency with respect to the process error percentage.
Fig. 22 shows n or p doping electrodes 21, 22, 23, 24, and dummy metal pads 21a, 22a, 23a, 24a on a bottom wafer substrate in an xy axis gyroscope according to an embodiment of the present invention. ), And a hermetic sealing wall 72, and a tsv interconnection.
FIG. 23 is a schematic sectional view taken along line BB 'of the xy-axis gyroscope of FIG.
24 is a diagram schematically illustrating a horizontally sensed xy-axis gyroscope plane according to another embodiment of the present invention.
25 and 26 are diagrams schematically showing a state in which the forms of FIG. 24 move in operation.
FIG. 27 schematically illustrates microfabrication processes for the bottom wafer 60 and the gyro wafer 70 in the xy-axis gyroscope according to an embodiment of the present invention.
FIG. 28 schematically illustrates microfabrication processes for the cap wafer 80 in the xy-axis gyroscope according to an embodiment of the present invention.
FIG. 29 schematically illustrates a wafer level vacuum package process for a gyro wafer 70 and a cap wafer 80 in an xy-axis gyroscope according to an embodiment of the present invention.
30 is a schematic view illustrating a manufacturing process for a TSV interconnection in an xy-axis gyroscope according to an embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

How it Works( Operation Fundamentals )

5 is a conceptual diagram illustrating a principle of driving a horizontal axis-type z-axis gyroscope according to an embodiment of the present invention, and FIG. 6 is an xy axis of a vertical-type horizontal sensing type according to another embodiment of the present invention. 7 is a conceptual diagram illustrating a gyroscope driving principle, and FIG. 7 is a graph illustrating a frequency response curve of the xy-axis gyroscope of FIG. 6.

As shown in FIG. 5, the horizontal sensing z-axis gyroscope or the vertical sensing xy-axis gyroscope of FIG. 6, the linear sensing mode and the rotation sensing mode are simultaneously applied to one sensor mass. A spring and a special type of sensing electrode were provided to enable 1 degree of freedom mode and 2 degree of freedom sensing mode. The principle of the present invention is applicable to all types of MEMs-based gyroscopes, including the vertical sensing x-y axis gyroscope.

FIG. 7 shows a frequency response curve for an x-y axis gyroscope having a 1 degree of freedom vertical excitation mode and a 2 degree of freedom horizontal sensing mode as shown in FIG. 6. Referring to FIG. 7, as shown in FIG. 6, two degrees of freedom sensor masses having variables x (t) and φ (t), respectively, are detected in a straight line (x) direction having two identical peak resonant frequencies fs₁ and fs₂. It has a frequency response curve for the mode and a frequency response curve for the sensing mode in the rotation (φ) direction. If the sensor mass of Fig. 6 is vertically propagated at the frequency fd with the maximum amplitude of amplitude Ad, the sensor mass is rotated with the linear amplitude x (t) having the maximum amplitude As_x and the maximum amplitude As_φ by the Coriolis force Fc in the x direction. The vibration φ (t) is linearly coupled to each other and vibrates. Accordingly, the output signal values at the two sensing electrodes Ra and the sensing electrode Rb of FIG. 6 are Ra_x (t) = x (t) + r₁φ (t), and Rb_x (t) = x (t), respectively. -r₂φ (t)

As such, for a z-axis gyroscope as shown in FIG. 5, or for an xy axis gyroscope as shown in FIG. 6, or for all other xy-axis or z-axis mem-based gyroscopes. By designing a support spring for the sensor mass to simultaneously operate the linear sensing mode (x) in the direction of force and the rotation sensing mode (φ) about the axis center perpendicular to the Coriolis force direction, two independent variables with two resonances Each frequency can be given.

FIG. 14 is a schematic diagram illustrating a one degree of freedom mathematical model for a frame 10 and support springs 12, 14, and 16 that are vertically excited in an x-y axis gyroscope according to an exemplary embodiment of the present invention. In FIG. 14, the frame 10 has an excitation such that the first sensor mass 30 and the second sensor mass 32 have anti-phase vibration components perpendicular to each other.

In FIG. 14, the vibration equation of the frame 10 is represented by Equation 1 below.

Where Jd is the mass moment of inertia for the entire frame 10 including the sensor masses 30 and 32, and kt₁ and kt₂ are the torsional stiffness of the beam relative to the support springs 12 and 14, respectively. torsional stiffness), and α denotes an interval ratio between the support springs 12, 14, and 16. The 2L₁Fes (t) term on the right side of the equation is the torque caused by the electrostatic force Fes (t) between the frame 10 and the bottom electrodes 21, 23, and Φ (t) is The rotation angle around the y axis.

The resonance frequency of the frame 10 calculated by the vibration equation of the frame 10 is expressed by Equation 2.

FIG. 15 schematically illustrates a mathematical model of sensor masses 30 and 32 and support springs 36 and 38 horizontally sensed in an x-y axis gyroscope according to an exemplary embodiment of the present invention.

Since the sensor masses 30 and 32 each have one mass, they have six degrees of freedom in three-dimensional space, and three linear (x, y, z) resonant frequencies and three rotations of different sizes. Direction (x, y, z) has a resonant frequency, respectively. In Fig. 15, two resonant frequencies related to the linear vibration (x) in the Coriolis force direction and the rotational vibration (φ) around the z-axis perpendicular to the Coriolis force are brought close to each other, and the other resonant frequencies are much higher or Alternatively, it can be designed to have a much lower resonance frequency.

In Figure 15, the vibration equation for the sensor mass (30, 32) is the same as the equation (3).

Where Js is the mass moment of inertia of the sensor masses 30 and 32, ms is the mass of the sensor masses 30 and 32, and k ₁ and k ₂ are the respective support springs 36a, 36b, 38a, Bending stiffness of 38b). s₁ and s₂ are the distance from the geometric center of each sensor mass (30,32) to the support springs (36a, 36b, 38a, 38b), and r₁ and r₂ are from the geometric center of each sensor mass (30,32) It means the distance to each intermediate point Ra of the differential sensing electrodes 41a, 43a; 45a, 47a, or each intermediate point Rb of the differential sensing electrodes 42a, 44a; 46a, 48a.

Fc (t) denotes the Coriolis force in the x direction, the variable x (t) denotes the linear vibration displacement of the sensor masses 30 and 32, and the variable φ (t) denotes the sensor mass bodies 30 and 32. The angle means the angle of rotation (). Accordingly, as shown in FIG. 15, the linear vibration amplitude in the x direction of the intermediate point Ra with respect to the differential sensing electrodes 45a and 47a of the sensor mass 32 is Ra_x in which the linear / rotation vibration mode of the sensor mass 32 is linearly coupled. (t) = x (t) + r₁φ (t), and the linear vibration amplitude in the x direction of the intermediate point Rb with respect to the differential sensing electrodes 46a and 48a of the sensor mass 32 is linear / Rb_x (t) = x (t)-r₂φ (t) combined with the linear vibration mode.

In FIG. 15, when the vibration equations for the sensor mass 30 or the sensor mass 32 are solved, the two sensed resonance frequencies fs ₁ and fs 2 for each sensor mass 30 and 32 on the xy plane are expressed by the following equation. It can be obtained as shown in 4.

Here, wx² = (k₁² + k₂²) / ms, wo² = (k₁s₁² + k₂s₂²) / Jc, K₁² = (k₁s₁-k₂s₂) / ms, and K₂² = (k₁s₁-k₂s₂) / Js.

If, in FIG. 15, the spring constant k₁, k₂ or distance s₁, s₂ values are approximated to each other, two sensing resonance frequencies (fs₁, fs₂) for each sensor mass (30, 32) on the xy plane are designed. You can adjust it accordingly.

On the other hand, in Fig. 15, the sensing resonance frequency of each sensor mass (30, 32) in the case of one degree of freedom detection system in which each sensor mass (30, 32) does not have a rotation sensing mode and only a linear sensing mode is fs = (1 / 2π) * sqrt (ks / ms). Where ks is the total spring stiffness in the linear direction, ks = 2 (k ₁ + k 2), and ms is the mass of the sensor mass (30, 32).

Thus, in Fig. 15, for the case of one degree of freedom sensing system in which each sensor mass 30,32 has only a linear sensing mode;

Fig. 18 shows the excitation resonance of the frame 10 when the etching process error (percentage) for the beam width 5um constituting the sensor mass support springs 36 and 38 varies from 97 [%] to 103 [%]. It is a Matlab simulation result showing the change of the frequency fd and the sensed resonance frequency fs of the sensor masses 30 and 32. Referring to Fig. 18, the detection resonance frequency fs changes abruptly even with the minute machining error of the beam width with respect to the sensor mass support springs 36 and 38. For example, a fine beamwidth processing error of 1% widens the excitation / detection resonance frequency difference to Δf = 240Hz (= fs-fd), and a 2% beamwidth processing error widens the excitation / detection resonance frequency difference to Δf = 500Hz. . Comparing this result with the frequency response curve of FIG. 3, at the same degree of vacuum, the detected amplitude As drops from about 30% to 10% relative to the peak value.

19 shows the excitation of the frame 10 when the etching process error (percentage) for the beam width 5um constituting the frame support springs 12, 14, 16 varies from 97 [%] to 103 [%]. Matlab simulation results showing the change in the resonance frequency fd and the sensing resonance frequency fs of the sensor masses 30 and 32 are shown. 19, it can be seen that the resonant frequency fd with respect to the fine processing error of the beam width with respect to the frame support springs 12, 14, and 16 is drastically changed. This phenomenon is as shown in FIG.

Fig. 20 shows the excitation / detection resonance frequencies (fs₁, fs₂) of the sensor according to the position s₁ variation of the sensor springs 36, 38 under k38 = k₂ and s₁ = s₂ conditions for the mathematical models of Figs. Matlab simulation results.

In FIG. 14, parameters Jd = 741.95e-17 [calculated for a system having one degree of freedom of the frame 10, with each beam width and thickness of the frame support springs 12, 14, and 16 being both 5um and 35um. kgm²], kt₁ = 1.62e-5 [Nm / rad] and kt₂ = 2.63e-5 [Nm / rad] are calculated by substituting the resonance frequency calculation formula of the frame 10, respectively. The beam widths and thicknesses of the springs 36 and 38 are also 5 μm and 35 μm, and the parameters Js = 50.52e-17 [kgm²] and ms = calculated for the two degree of freedom detection system of the sensor masses 30 and 32. 1.13e-8 [kg], k₁ = 0.506e3 [N / m], k₂ = 0.506e3 [N / m], s₁ = s₂ = 207 ~ 215 [um] are calculated by substituting the sensor resonance frequency The result is as shown in FIG. If the position of the sensor support spring (36,38) is s₁ = s₂ = 210 [um], the excited resonant frequency is fd = 15,007 [Hz], and the sensed resonant frequencies are fs₁ = 14,845 [Hz] and fs₂ = 15,163 [ Hz]. From the simulation results of FIG. 20, the spring positions s s and s 2, which take into account the optimum resonant frequency difference for the two degree of freedom sensing system of FIG. 15, can be obtained, respectively.

Fig. 21 is the same as the simulation case of Fig. 20 after the frame 10 and the sensor mass bodies 30 and 32 under the same conditions as those of Figs. 16 and 17 are formed for the mathematical models as shown in Figs. 14 and 15. For the case where the support springs 36,38 are s 조건 = s₂ = 210 [um] under design conditions; Matlab simulation results showing the variation of the sensing resonance frequency (fd) of the frame and the sensing resonance frequency (fs 공진, fs₂) of the frame when the etching process error (percentage) for each beam width varies from 97 [%] to 103 [%]. to be.

That is, as shown in Figure 21, the xy-axis gyroscope as in the present invention, as shown in Figure 15, one sensor mass as a two degree of freedom sensing system using a combination of linear / rotational sensing mode, the second frame and the support spring, And the gyro basic components such as the sensor and the support spring are composed of beams and holes having the same width, the same thickness, and the same length ratio, and the third beam width of the frame and the sensor are all the same size and arranged in parallel with each other. If the dummy beam springs with the same width are arranged at the same side of each support spring, the resonance frequency (fd) and the sense resonance are generated even if machining errors occur for all the basic components of the MEMs-based gyroscope. The frequency (fs₁, fs₂) will fluctuate and maintain a similar form where fd lies between fs₁, fs₂, as shown in Figure 21, and if so the sensor amplitude (As) There will be no change.

On the other hand, in the mathematical model of the sensor of FIG. 15, if the rigidity k₁, k₂ or position s₁, s₂ values of the support springs 36,38 are slightly different, the sensor becomes a slightly non-symmetric structure, leading to an x-direction Coriolis. Since not only the force Fc but also the rotation moment by Fc are applied together, linear and rotational vibrations occur simultaneously in the sensor masses 30 and 32. At this time, the differential sensing electrodes 41a, 42a, 43a, 44a, 45a, 46a, 47a, and 48a of the sensor masses 30 and 32 rotate with the linear vibration displacement x (t) of the sensor masses 30 and 32, respectively. The linear displacement r₁φ (t) due to the vibration is linearly coupled and outputs a signal x₁ (t) = x (t) + r₁φ (t), or x₂ (t) = x (t) + r₂φ (t).

Mechanical composition

8 shows a schematic structure of a horizontally sensed x-y-axis gyroscope with a vertical on the x-y plane according to one embodiment of the invention.

FIG. 9 shows, in the x-y-axis gyroscope of FIG. 8, a frame 10 being vertical, and a frame support spring 12 attached to the anchor 26 sidewall; Support springs 14 and 16 of double-sided up-and-down symmetrical double-link shape located at both end edges of the x-direction to enhance the vertical restoring force of the frame 10; A schematic representation of the symmetric double folded shape dummy spring 18 attached to the sidewall of the anchor 26 to suppress the x-direction bending deformation of the frame support spring 12. Drawing.

FIG. 10 is a linear vibration displacement and rotation vibration angle of the sensor masses 30 and 32 and the support springs 36a, 36b, 38a and 38b, and the sensor masses that are horizontally sensed in the xy-axis gyroscope of FIG. FIG. 4 is a diagram schematically illustrating double sensing electrodes 41a, 42a, 43a, and 44a; 45a, 46a, 47a, and 48a for differential sensing of angles simultaneously.

In the embodiment of FIG. 9,

The frame 10 is allowed to torsionally rotate about the y axis by two support springs 12 attached to the two anchor 26 sidewalls. In the x-y plane, the support spring 14 generates a restoring torque to help the both ends of the x direction of the frame 10 to be restored to their normal position after the torsional deformation of the frame 10. The support spring 16 serves as a link or rotation bearing connecting the frame 10 edge and the support spring 14. The planar link 15 is one link that mechanically connects the support spring 14 and the support spring 16. The dummy beam spring 18 having a double fold symmetrical double-folded shape is attached to both anchors 26 of the frame 10 so that the bending direction of the frame 10 by the support springs 12 and 14 may be changed. And the rotational movement of the frame 10 about the vertical axis (z) at the same time.

In the embodiment of FIG. 10,

Two pairs of sensor masses 30 and 32 are located at a distance apart from the left and right and up and down with respect to the y-axis so as to enable linear vibration in the Coriolis force (x) direction and rotational vibration about the center of the sensor masses 30 and 32, respectively. It is connected to the frame 10 by two pairs of support springs 36a, 36b, 38a and 38b. The Coriolis force direction (x) operation of the sensor masses 30 and 32 is the distance or area between the sensor masses 30 and 32 and the sensing electrodes 41a, 42a, 43a, 44a; 45a, 46a, 47a, 48a. It can be detected as a capacitance change according to the change. Each of the sensing electrodes 41a, 42a, 43a, 44a; 45a, 46a, 47a, 48a may use either a comb electrode or a plate electrode. The sensing electrodes 41a, 42a, 43a, 44a; 45a, 46a, 47a, 48a are attached to the sides of the anchors 41, 42, 43, 44; 45, 46, 47, 48 fixed to the wafer substrate, respectively.

In the embodiment of FIG. 11,

The x-y-axis gyroscope of FIG. 8 is in the interior space between the bottom wafer 60 and the cap wafer 80 surrounded by hermetic seal walls 72, 74, 76 of the gyro wafer 70. The support spring 12 allows rotational vibration of the frame 10 about the y-axis, and the support spring 14 serves to reinforce the vertical restoring force with respect to the end edge of the frame 10, and the support spring ( In (16), the torsional deformation in the center of the y-axis and the bending deformation in the x-axis direction occur at the same time and serve as a rotating bearing. And the support spring 14, the flat link 15 and the support spring 16 is a basic component of the double link device for mechanically connecting the frame edge and the anchor 25. There are bottom electrodes 21 and 23 for vertically moving the frame 10 on the bottom wafer 60 under the frame 10 and the sensor masses 30 and 32, respectively. There are bottom electrodes 22 and 24 for sensing a change in capacitance, respectively.

12 and 13 are diagrams schematically showing a state in which the forms of FIG. 11 move in operation.

In FIG. 12, the electrostatic force + Fes (t) in the z-axis + direction is generated by the bottom electrode 21, and the electrostatic force -Fes (t) in the z-axis-direction is generated by the bottom electrode 23. Occurs. Then, the frame 10 receives a rotational moment in a clockwise direction, the sensor mass 30 receives the x-axis-coriolis force -Fc (t) and operates in the -x axis, and the sensor mass 32 is the x-axis + It receives direction Coriolis force + Fc (t) and operates on the + x axis. In FIG. 13, the constant power −Fes (t) in the z-axis direction is generated by the bottom electrode 21, and the constant power + Fes (t) in the z-axis + direction is generated by the bottom electrode 23. At this time, the frame 10 receives a counterclockwise rotation moment, the sensor mass 30 receives the x-axis + direction Coriolis force + Fc (t) and operates in the + x axis, and the sensor mass 32 is the x-axis. Receives the -direction Coriolis force -Fc (t) and operates on the -x axis.

FIG. 16 shows a frame 10 including a beam and an etching hole having the same width and the same thickness as the support springs 14 and 16, and a multiple of the length in the xy-axis gyroscope of FIG. 8, and the sensor support. Figures schematically show the sensor masses 30 and 32 including beams and holes having the same width and the same thickness as the springs 36a, 36b, 38a, and 38b, and a multiple of the length. If the frame 10 and the support springs 12, 14, and 16 are composed of a beam 31 and an etching hole 33 having the same width, the same thickness, and the constant multiple lengths, the sensor mass 30, 32) a single xy-axis gyroscope chip if the support springs 36a, 36b, 38a, 38b are composed of a beam 31 having the same width, the same thickness, and the same length and the etching hole 33, respectively. Since the etching process environment for these is the same, it can be said that the process error occurs at about the same rate. That is, when the process errors for each spring and mass occur at the same ratio, the excitation resonant frequency fd of the frame 10 and the detection resonant frequencies fs₁, fs₂ of the sensor masses 30 and 32 are almost unchanged. will be.

In FIG. 17, in addition to the design conditions as shown in FIG. 16, first, the frame support springs 14, 16, the sensor support springs 36a, 36b, 38a, 38b, and the frame dummy beam springs 13, 17 are all the same. It has a beam thickness equal to the beam width, and then the respective beams constituting the frame and the sensor are all arranged in parallel, and finally, on the left and right sides of the support spring 14, the same size as the beam width of the support spring 14 Dummy beam springs 13 having a width equal to the beam width of the support spring 14 are spaced apart from each other and are attached between the double links 15 and the anchors 25, respectively. A dummy beam spring 17 is attached to the side of the support spring 16 with a width equal to the beam width of the support spring 16 at intervals equal to the beam width of the support spring 16. .

If, in addition to the design conditions as shown in Fig. 16, further conditions as shown in Fig. 17 are added, the xy-axis gyroscope basic components of the present invention are all composed of beams having the same width, thickness, and length ratio, and these The etching process errors occur at almost the same rate because all the etching process conditions are the same, and as shown in FIG. 21, the resonance frequency fd for the frame and the sensing resonance frequencies fs₁ and fs₂ for the sensor are almost the same according to the process error. They stay the same and change at the same rate.

FIG. 22 illustrates the n or p electrodes 21, 22, 23, and 24 on the front surface of the bottom wafer, and the dummy metal pads 21a on the front surface of the bottom wafer, for the xy-axis gyroscope according to the exemplary embodiment of FIG. 8. And 22a, 23a, 24a, and silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b, 43b, 44b, 45b, 46b, 47b, 48b, and the sealing wall 72 of the bottom wafer. A schematic plan view. And FIG. 23 schematically shows the BB 'cross section in the x-y-axis gyroscope of FIG.

22 and 23, the sealing wall 72 is one wall which cuts the inside and the outside for vacuum sealing to the x-y axis gyroscope. The bottom electrodes 21 and 23 are n or p doped electrodes for the vertical purpose of the frame 10 doped with boron or phosphorus on the wafer substrate, and the bottom electrodes 22 and 24. Is an n or p doping electrode for measuring the vertical gap variation of the frame 10. The silicon through electrode 26b of the bottom wafer 60 means a wiring connection for supplying power to the frame 10 and the sensor masses 30 and 32; The silicon through electrodes 41b, 42b, 43b, 44b; 45b, 46b, 47b, 48b of the bottom wafer 60 are detected by the sensor sensing electrodes 41a, 42a, 43a, 44a; 45a, 46a, 47a, 48a. Wiring for outputting a signal to the outside; The silicon through electrodes 21b and 23b of the bottom wafer are wirings for supplying power to the bottom electrodes 21 and 23; The silicon through electrodes 22b and 24b are wirings for sensing signals from the bottom electrodes 22 and 24. The dummy metal pads 21a, 22a, 23a, and 24a are one dummy metal pads deposited with conductive metal on the doping electrodes 21, 22, 23, and 24 connected out of the sealed wall, and the silicon through electrodes 21b, 22b, and 23b. And 24b and electrically connect the doping electrodes 21, 22, 23, and 24 to each other.

22 and 23, the air through hole 83 of the cap wafer 80 is a gas at the time of bonding the metal 76 in the wafer hermetic bonding process between the cap wafer 80 and the gyro wafer 70 in the vacuum chamber. It acts as a venting hole through which the gyroscope chip maintains a uniform vacuum over the entire wafer area. The air through hole 83 of the cap wafer 80 is also used for the purpose of depositing metal on the dummy metal pads 21a, 22a, 23a, and 24a outside the sealed wall 72.

In Fig. 23, in order to drill a silicon through electrode having a diameter of 20 to 30 μm in the bottom wafer 60, the thickness of the bottom wafer 60 is inevitably thinned to about 100 μm due to the high section ratio limit of the etching process. When the thickness of the bottom wafer 60 becomes thin, the frame support anchors 25 and 26 alone cannot absorb the vibration energy having the vertical direction with respect to the frame 10, and thus the pillar 78 between the cap wafer 80 and the gyro wafer 70 may be reduced. , 79) and the vibration energy of the frame 10 can be divided and divided into the bottom wafer 60 and the cap wafer 80, respectively.

While an embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and of course, the present invention may be embodied in various other forms within the scope of the technical idea.

Produce( Fabrication )

In a preferred embodiment, the x-y-axis gyroscope having the structure and operation is fabricated using semiconductor microfabrication process technology. Semiconductor microfabrication processes include two methods: surface micromachining, which produces a thin structure by repeating deposition and etching on a silicon substrate, and bulk micromachining, which forms a thick structure by processing a silicon substrate.

27, 28, 29, and 30 schematically illustrate exemplary manufacturing sequences suitable for manufacturing embodiments of the present invention.

FIG. 27 schematically illustrates a sequence of steps suitable for manufacturing the bottom wafer 60 and the gyro wafer 70.

In step S10 of FIG. 27, a high resistance silicon wafer 100 of about 10 to 20 [Ωcm] is used as the bottom wafer 60.

From step S10 to step S12 of FIG. 27, boron or phosphorus is infiltrated into the front surface of the bottom wafer 60 at a temperature of about 800 to 1,000 [° C.], so that the n doping electrode or the p doping is carried out. Electrodes 21, 22, 23 and 24 are made. The thermal expansion problem of the n or p electrode due to the high temperature process is solved by annealing. Since the n or p electrode is doped to the high resistance silicon wafer, the parasitic capacitance generated by the excitation voltage is relatively small.

From the step S12 to the step S13 of FIG. 27, a SiO 2 insulator having a thickness of 2 to 3 [um] at a temperature of about 800 to 1,000 [° C.] over the entire surface of the bottom wafer 60 and the doping electrodes 21, 22, 23, and 24. (74) is deposited.

From step S13 to step S14 of FIG. 27, a low resistance silicon wafer 100 of about 0.01 [Ωcm] is used as the gyro wafer 70, and the gyro wafer 70 is SiO 2 insulator at a temperature of about 600 [° C.]. Wafer bonding is performed on the 74, and then a thinning step is performed on the gyro wafer 70 having a thickness of about 500 [um] to a thickness of 35 to 40 [um] at room temperature. Thinning is a method by which conventional grinding and polishing are suitable. In this case, the gyro wafer 70 is the same as a silicon on insulator (SOI) wafer.

From step S14 to step S15 of FIG. 27, the metal wall 76 having a thickness of about 1 to 5 [um] for the hermetic sealing wall between the gyro wafers 70 is patterned. .

In step S15 to step S16 of FIG. 27, after PR lithography patterning on the gyro wafer 70, the etching is performed by deep reactive ion etching, that is, a deep reactive ion etching (RIE) method.

From step S16 to step S18 of FIG. 27, the SiO 2 insulator 74 between the bottom wafer 60 and the gyro wafer 70 is removed with some sacrificial layer.

FIG. 28 schematically illustrates microfabrication processes for a cap wafer 80 in an x-y-axis gyroscope according to an embodiment of the present invention.

In step S20 of FIG. 28, a high resistance silicon wafer 100 of about 10 to 20 [Ωcm] is used as the cap wafer 80.

Going from step S20 to step S22 of FIG. 28, the metal wall 77 having a thickness of 4 to 5 [um] for the sealing wall bonding between the wafers is patterned on the back side of the cap wafer 80.

While going from step S22 to step S24 of FIG. 28, the cavity 81 for protecting the MEMs structure is etched from the back of the cap wafer 80 by a deep RIE method.

Going from step S24 to step S26 of FIG. 28, an air through hole 83 having a size of about 150 × 150 [um 2] is etched from the front side of the cap wafer 80 by a deep RIE method.

From step S26 to step S28 of FIG. 28, oxygen (O) and nitrogen (N) adhere well to the cavity ceiling of the cap wafer 80 at a thickness of about 400 [nm] at a temperature of about 400 [° C.]. Getter 82 is deposited. The getter 82 has an effect of decreasing the degree of vacuum when the temperature rises.

29 is a schematic cross-sectional view of a wafer level vacuum package for an gyro wafer 70 and a cap wafer 80 in the form of an SOI in an xy axis gyroscope according to an embodiment of the present invention. to be.

In step S30 of FIG. 29, the vacuum degree in the vacuum chamber is maintained to be 1 to 3 [mTorr]. A relatively high temperature bonding process is required to bond the cap wafer 80 to the gyro wafer 70, which includes eutectic metal bonding, glass bonding, solder bonding, and gold eutectic bonding. (gold eutectic bonding), Si to SiO 2 fusion bonding (Si to SiO 2 fusion bonding), and Si to Si fusion bonding (Si to Si fusion bonding) are included. Any process may be used in the embodiment of the present invention.

Going from step S30 to step S32 of FIG. 29, the bottom wafer 60 is thinned from about 500 [um] to 100 [um] thick.

30 is a schematic diagram illustrating microfabrication processes for silicon through electrode wiring in an x-y-axis gyroscope according to an embodiment of the present invention.

In step S40 of FIG. 30, dummy metal pads 21 a, 22 a, 23 a, and 24 a on the front surface of the bottom wafer 60 are deposited outside the sealing wall 72. In step S40 of FIG. 30, the dummy metal pads 21a, 22a, 23a, and 24a serve as an etch stop.

Going from step S40 to step S42 of FIG. 30, the silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b, 43b, 44b, having a diameter Ø 20 to 30 [um] on the bottom wafer 60 back surface; 45b, 46b, 47b, 48b) are etched by the deep RIE method. At this time, the deep RIE process for the silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b, 43b, 44b, 45b, 46b, 47b, 48b is performed by dummy metal pads 21a, 22a, 23a, and 24a. And etching speed between the bottom wafer 60 and the dummy metal pads 21a, 22a, 23a and 24a and the insulator 74, and the dummy metal pads 21a, 22a, 23a and 24a and the gyro wafer 70. This is done using etch rate selectivity.

Going from step S42 to step S44 in FIG. 30, first, the entire back side of the bottom wafer 60 and the silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b, 43b, 44b, 45b, 46b, 47b, 48b) by depositing and stacking an insulator (SiO 2) on the side wall, and then the entire bottom surface of the bottom wafer 60 and the silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b, 43b, 44b, 45b, 46b, 47b, 48b When the oxide etched back the insulator (SiO 2) deposited on the bottom in the hole, the silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b 43b, 44b, 45b, 46b, 47b, 48b The insulator SiO 2 remains only in the side walls. Subsequently, a seed metal is deposited in holes of the silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b, 43b, 44b, 45b, 46b, 47b, and 48b. MEMS gyro by metal filling the silicon through electrodes 21b, 22b, 23b, 24b; 26b; 41b, 42b, 43b, 44b, 45b, 46b, 47b, 48b in an electroplating batch process. Internal and external wiring connections are completed.

Going from step S44 to step S46 in Fig. 30, the silicon through electrode outlets 21c, 22c, 23c, 24c; 26c; 41c, 42c, 43c, 44c, 45c, 46c, 47c, 48c on the bottom of the bottom wafer 60; Bumping after ball patterning.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements may be made by those skilled in the art using the basic concept of the present invention as defined in the following claims. It belongs to the scope of the present invention.

10: frame
12,14,16: frame support spring
18: frame dummy spring
25,26: frame anchor
26a: Anchor in front of bottom wafer for frame and sensor mass excitation
26b silicon through electrode on bottom wafer for frame and sensor mass excitation
26c back bumping ball of bottom wafer for frame and sensor mass excitation
21,22,23,24: n-electrode, or n + electrode on the bottom wafer front
21a, 22a, 23a, 24a: dummy metal pads on the front of the bottom wafer for n- or n + electrodes
21b, 22b, 23b, 24b: silicon through electrode of bottom wafer, for n-electrode or n + electrode
21c, 22c, 23c, 24c: back bumping ball of bottom wafer for n-electrode or n + electrode
30,32: sensor mass
36a, 36b, 38a, 38b: Sensor mass support spring
41,42,43,44,45,46,47,48: Anchor for sensor mass electrode
41a, 42a, 43a, 44a, 45a, 46a, 47a, 48a: flat electrode or comb electrode for sensor mass detection
41b, 42b, 43b, 44b, 45b, 46b, 47b, 48b: silicon through electrode of the bottom wafer for sensor mass detection
41c, 42c, 43c, 44c, 45c, 46c, 47c, 48c: Bottom Wafer Back Bumping Ball for Sensor Mass Detection
60: bottom wafer
70: Gyro Wafer
80: cap wafer

Claims (19)

A frame disposed parallel to the bottom wafer substrate;
In the excitation mode, the sensor mass is excited with one degree of freedom, and in the sensing mode, the sensor mass is sensed at two degrees of freedom by a Coriolis force when an external angular velocity is input to the frame;
At least two sensing electrodes for measuring each sensing displacement of two degrees of freedom by the sensor mass; And
At least two sensor mass support springs connecting the sensor mass and the frame and allowing the sensor mass to have respective sensing displacements of two degrees of freedom
Memes-based gyroscope made, including. The method of claim 1,
The sensing electrode has a constant distance from the center of the sensor mass to measure the linear vibration displacement in the Coriolis force direction with respect to the sensor mass and the rotational vibration angle of another axis center perpendicular to the Coriolis force direction. Arranged separately from one another
Memes-based gyroscope characterized by. The method of claim 1,
The support springs are separated from each other at a position away from the center of the sensor mass so that linear vibration in the Coriolis force direction and rotational vibration of another axis center perpendicular to the Coriolis force direction are simultaneously possible with respect to the sensor mass.
Memes-based gyroscope characterized by. The method of claim 3,
The sensor mass supporting spring is a beam-shaped spring capable of bending deformation or torsional deformation, respectively, to enable linear vibration in the Coriolis force direction and rotational vibration about another axis perpendicular to the Coriolis force direction.
Memes-based gyroscope characterized by. 5. The method according to any one of claims 1 to 4,
The frame is parallel to the xy plane and is vertically oscillated with respect to the bottom wafer substrate by at least one bottom electrode arranged on the bottom wafer substrate and at least one electrostatic force applied through the bottom electrode. Has a degree of freedom of one degree of freedom or has a degree of freedom of rotational oscillation (rotational oscillation) around one axis parallel to the bottom wafer substrate,
The sensor mass is a linear oscillation in the Coriolis force direction caused by an external angular velocity input to one axis center parallel to the bottom wafer substrate and a rotational vibration in the vertical axis center with respect to the Coriolis force direction. with two degrees of freedom sensing modes simultaneously performing rotational oscillation
Memes-based gyroscope characterized by. 5. The method according to any one of claims 1 to 4,
The frame is parallel to the xy plane and is horizontal in a direction parallel to the xy plane by at least one excitation electrode arranged in the frame lateral direction and at least one electrostatic force applied through the excitation electrode. Has a one degree of freedom mode that oscillates (lateral oscillation) or one degree of freedom mode that rotates (rotational oscillation) about the z-axis perpendicular to the xy plane,
The sensor mass has a linear oscillation in the Coriolis direction that operates in a vertical direction with the bottom wafer substrate by an external angular velocity input to one axis center parallel to the bottom wafer substrate and another axis center perpendicular to the Coriolis direction. With two degree of freedom sensing modes for simultaneously rotating vibrations
Memes-based gyroscope characterized by. 5. The method according to any one of claims 1 to 4,
The frame has a mode of one degree of freedom parallel to the xy plane and horizontally oscillates in a direction parallel to the bottom wafer substrate, or a mode of one degree of freedom that rotates about a z axis perpendicular to the xy plane. Has,
The sensor mass is a linear vibration in a Coriolis direction that operates horizontally on the bottom wafer substrate by an external angular velocity input to a z axis center perpendicular to the bottom wafer substrate and another axis center perpendicular to the Coriolis direction. With two degree of freedom sensing modes for simultaneously rotating vibrations
Memes-based gyroscope characterized by. The method of claim 1,
The frame is connected to the bottom wafer substrate by at least one frame support spring attached to the fixed anchor sidewall of the bottom wafer substrate,
The sensor mass support springs are arranged in parallel with each other while having a beam width of the same size as the frame support spring and a beam thickness of the same size,
The frame includes a beam having a width equal to a beam of the frame support spring and a predetermined multiple of length, and a hole having a width and a constant multiple of the same size as a beam of the frame support spring. Consisting of,
The sensor mass is composed of a beam having a width and a constant multiple of the same size as the beam of the sensor mass support spring, and a hole having a width and a constant multiple of the same size as the beam of the sensor mass support spring.
Memes-based gyroscope characterized by. The method of claim 1,
The frame is connected to the bottom wafer substrate by at least one frame support spring attached to the fixed anchor sidewall of the bottom wafer substrate,
It has the same width and the same thickness as the beam of the frame support spring, spaced at both sides of the frame support spring by the same width as the beam of the frame support spring, respectively on the side of the frame or the anchor Attached Dummy Beam Spring
MEMS-based gyroscope further comprising a. The method of claim 1,
Two bottom electrodes having the same area are separately disposed on the wafer substrate at regular intervals,
One frame parallel to the wafer substrate is tuned fork with rotational vibration caused by anti-phase vertical electrostatic forces applied through the two separate bottom electrodes, respectively. ) Has an antiphase vertical velocity component of
Two sensor masses having the same size are connected to each other in the form of a decoupled structure on the frame and the xy plane so as to necessarily operate in opposite directions by the rotational vibration of the frame,
Each support spring for the sensor mass has an antiphase Coriolis in the direction of another axis perpendicular to the angular velocity input axis of the two sensor masses connected to the frame when the angular velocity is input about an axis on an xy plane to the frame. Supporting the sensor masses on the frame so as to be operated in opposite directions by force
Memes-based gyroscope characterized by. 11. The method of claim 10,
A torsional spring in the form of a symmetric double link, which supports both end edges of the frame, respectively, and reinforces a restoring force in the vertical direction with respect to both end edges of the frame.
MEMS-based gyroscope further comprising a. 11. The method of claim 10,
For the purpose of suppressing bending deformation in the Coriolis bending direction with respect to the frame, the Coriolis bending direction stiffness of the frame is increased, and the torsional stiffness with respect to the other direction axis of the frame is increased. Is a small, bilaterally symmetric double folded dummy beam spring.
MEMS-based gyroscope further comprising a. The method according to any one of claims 1 and 8 to 12,
Two bottom electrodes having the same area are separately arranged at regular intervals on the bottom wafer substrate,
The two parallel frames parallel to the wafer substrate and separated from each other are in a posture parallel to the bottom wafer substrate by anti-phase electrostatic forces applied through the two separate bottom electrodes. Vertical vibration in the form of a tuning fork,
The two sensor masses having the same size are connected to each other in a decoupled structure on an xy plane with the two frames operating in opposite directions;
The two sensor mass support springs are subjected to antiphase Coriolis forces in different axial directions perpendicular to the angular velocity input axis when the angular velocity is input about one axis on the xy plane to the frame in opposite directions. Each sensor mass is connected to the frame to operate,
The sensing electrodes are arranged separately in the left and right or up and down directions of the center of the sensor mass in order to detect each movement displacement with respect to linear vibration and rotational vibration of the sensor mass.
Memes-based gyroscope characterized by. 13. The method according to any one of claims 10 to 12,
The two sensor masses,
When the anti-phase Coriolis force of the tuning fork type is applied in one axial direction on the xy plane in the frame, the first sensor mass pair composed of the two sensor masses is non-combined with the frame such that the first pair of sensor masses operates in opposite directions on the axis. A single axis gyroscope connected with a spring structure;
A second sensor composed of the other two sensor masses when the anti-phase coriolis force in the form of a tuning fork acts in another axial direction perpendicular to the axis on which the coriolis force acts in the frame of the monoaxial gyroscope on the xy plane Another uniaxial gyroscope connected by the frame and the non-coupled spring structure such that the pair of masses respectively operate in opposite directions to the axis on which the antiphase Coriolis force acts.
MEMS-based gyroscope further comprises a. 6. The method of claim 5,
The bottom wafer substrate is a silicon wafer substrate,
The bottom electrode may include at least one n electrode or p electrode doped with boron or phosphorus in a predetermined region on the silicon wafer substrate;
The MEMS-based gyroscope is manufactured by bulk micromachining a silicon on insulator (SOI) wafer bonded to one another silicon wafer after an insulator is deposited on the silicon wafer substrate;
In another silicon wafer, at least one cavity for the protection of the MEMs-based gyroscope is bulk processed into a cap wafer;
The bottom wafer substrate including the doping electrode, the MEMS SOI wafer including the MEMS-based gyroscope, and the cap wafer including the cavity are triple-layered in a vacuum chamber. For wafer level hermetic sealing
Memes-based gyroscope characterized by. 16. The method of claim 15,
In order to provide the same vacuum package processing environment for each gyroscope chip individually for the total area of the MEMS SOI wafer,
The MEMS SOI wafer comprises: at least one vacuum sealing wall for in-vacuum operation of the MEMS-based gyroscope; The bottom wafer substrate may include at least one doped electrode having electrical wires connected to each other inside and outside the sealing wall;
The cap wafer includes at least one hermetic sealing wall for maintaining a vacuum state of the MEMs-based gyroscope and a back side at the front side of the cap wafer outside the sealing wall. At least one air through hole completely through
MEMS-based gyroscope further comprising a. 16. The method of claim 15,
At least one through silicon via (TSV) for interconnection between a bottom surface of the bottom wafer substrate and a front doped electrode of the bottom wafer substrate; At least one silicon through electrode for interconnection between the back surface of the bottom wafer substrate and the MEMS wafer structure
MEMS-based gyroscope further comprising a. 18. The method of claim 17,
The triple wafer is hermetically bonded to the bottom wafer substrate, the MEMS SOI wafer and the cap wafer,
At least one dummy metal pad deposited on a surface of a front doped electrode of the bottom wafer substrate under an air through hole of the cap wafer,
A MEM-based gyroscope for etching the hole-shaped silicon through electrode using an etch rate selectivity between the bottom wafer substrate, the doping electrode, the insulator, and the MEMs SOI wafer. 16. The method of claim 15,
A frame anchor is fixed to the bottom wafer substrate in order to distribute the vibration energy having the perpendicularity with respect to the frame to the bottom wafer substrate and the cap wafer, respectively.
The cap wafer for protecting the MEMs-based gyroscope, the cap wafer further comprises at least one or more pillars, and bonded to the frame anchor using the one or more pillars.

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