KR20060124267A - The in-plane 3-axis inertia measurement systems with the exact alignment - Google Patents

Abstract

A flat type 3-axis inertia measurement system with an exact alignment are provided to simplify a packaging process, increase a yield, and minimize a size of a manufactured inertia sensor. A flat type 3-axis inertia measurement system with an exact alignment includes an x-axis accelerating system(100) for detecting a translation motion of the x-axis, a y-axis accelerating system for detecting a translation motion of the y-axis, and a z-axis accelerating system for detecting a rotation motion of the z-axis.

Description

The in-plane 3-axis inertia measurement systems with the exact alignment}

1A and 1B are schematic views of a conventional three axis inertial measurement system.

Figure 1c is a photograph of the conventional three-axis inertial measurement system shown in Figure 1b.

2A and 2B are a plan view and a perspective view of a three-axis inertial measurement system according to the present invention.

3A to 3F are cross-sectional views illustrating a process of fabricating a three-axis inertial measurement system according to the present invention on an SOI substrate.

4A to 4L are cross-sectional views illustrating a process of fabricating a triaxial inertial measurement system according to the present invention on a single crystal silicon substrate.

5A to 5F are cross-sectional views illustrating a process of fabricating a three-axis inertial measurement system according to the present invention on a silicon-on-glass substrate.

The present invention relates to a three-axis inertial measurement system that can detect the inertial force in each direction of the x-axis, y-axis and z-axis during the three-dimensional motion. The three-axis inertial measurement system according to the present invention is an x-axis accelerometer for detecting the translational motion of the x-axis on the single substrate, the y-axis accelerometer for detecting the translational motion of the y-axis, and the z-axis rotational motion for detecting the translational motion of the y-axis. An axial angular meter is formed.

MEMS technology uses a silicon process to form a specific part of the system by integrating it on a silicon substrate in a micrometer-specific shape. The MEMS technique is based on a semiconductor device manufacturing technique such as a thin film deposition technique, an etching technique, a photographing technique, an impurity diffusion and implantation technique.

Inertial sensors (ie, MEMS devices for detecting inertial forces), including acceleration sensors and angular velocity sensors, are typical devices manufactured by MEMS technology and can measure translational and rotational motions. Capacitive inertial sensors are widely used due to their simple manufacturing process, insensitive to temperature changes, and low nonlinearity. Inertial sensors are applied to various fields such as guidance and navigation, portable devices, camcorders, three-dimensional input devices, and games, and the application fields and demand are expected to explode.

The conventional three-axis inertial measurement system that can detect the inertial force in each direction of the x-axis, y-axis and z-axis during the three-dimensional motion, after separately manufacturing a single-axis inertial sensor that detects the inertia of one axis, Combination of three 1-axis inertial sensors. For example, as shown in FIG. 1A, three single-axis accelerometers are arranged in a planar manner, or as shown in FIG. 1B and FIG.

However, in the conventional three-axis inertial sensor system as described above, since the one-axis accelerometer or one-axis angular velocity meter is manufactured separately, these inertial sensors are aligned and assembled in the x-axis, y-axis, and z-axis. An error occurs, and therefore, the performance of the three-axis inertial measurement system is degraded and there is a limit to miniaturization.

The present invention has been made to solve the problems described above, in the three-axis inertial measurement system according to the present invention, an accelerometer and an angometer are formed on the same substrate at the same time to detect the inertia of each axis. Therefore, the alignment error between the three axes does not occur to prevent performance degradation, the packaging process is simpler than the conventional assembly method, the yield is increased, and the size can be minimized. In addition, it is manufactured by SBM (Sacrificial Bulk Micromachining) technology that can produce high aspect ratio structure with one mask, and completely solves the problem of residual stress, insulation and reliability caused by putting phenomenon, which is a problem of existing SOI or SOG process method. High performance and high reliability sensors can be manufactured.

It is therefore an object of the present invention to provide a three-axis inertial system without alignment errors.

The present invention relates to a three-axis inertial measurement system that can detect the inertial force in each direction of the x-axis, y-axis and z-axis during the three-dimensional motion.

More specifically, the present invention provides an x-axis accelerometer for detecting the translational motion of the x-axis, an y-axis accelerometer for detecting the translational motion of the y-axis, and a z-axis angular velocity detector for detecting the rotational motion of the z-axis on a single substrate. A three-axis inertial measurement system.

In the present invention, the x-axis accelerometer, y-axis accelerometer and z-axis accelerometer are formed on the same plane of a single substrate (for example, a single crystal silicon substrate, an SOI substrate, or a silicon-on-glass (SOG) substrate) It is preferable.

The three-axis inertial measurement system according to the present invention can be manufactured by simultaneously forming the x-axis accelerometer, the y-axis accelerometer and the z-axis angometer on a single substrate by a sacrificial bulk micromachining (SBM) process. Thus, the accelerometer and the angular velocity meter can be formed on the same plane without alignment error. In addition, since the space required for alignment is minimized, the size of the 3-axis inertial sensor can be minimized. In addition, since the three-axis inertial sensor can be packaged at the same time, the packaging process can be simplified and the yield can be increased.

The SBM process technology is a technique for fabricating a microstructure shape on a (111) single crystal silicon substrate, and etching the sacrificial layer with a basic aqueous solution to float the microstructure from the silicon substrate (Korean Patent Publication No. 1999-79113).

In the present specification, the accelerometer or the angular meter means a MEMS device capable of detecting acceleration or angular velocity by detecting a change in capacitance between an internal mass and a detection electrode during a translational or rotational movement.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited by the following examples.

2A and 2B are plan and perspective views, respectively, of a three-axis inertial measurement system according to the present invention.

As shown in the drawings, the three-axis inertial measurement system 10 according to the present invention includes an x-axis accelerometer 100 for detecting the x-axis translational motion, a y-axis accelerometer 101 for detecting the y-axis translational motion, And a z-axis angular tachometer 200 for detecting the rotational movement of the z-axis are formed on the same plane of a single substrate.

As the single substrate, any substrate composed of single crystal silicon, for example, a conventional single crystal silicon substrate, an SOI substrate, an SOG substrate, or the like can be used.

The accelerometer (100, 101) or angular tachometer (200) detects a change in capacitance between the mass (110, 215) and the detection electrodes (140, 141, 150, 151, 240, 250) in the translational or rotational motion To detect acceleration or angular velocity.

In general, the x-axis accelerometer 100 has an internal mass 110, a ground electrode 120 grounded as a reference voltage, and an electrode 130 applying a carrier wave to the internal mass 110, as shown in the drawing. 131, detection electrodes 140 and 141 for detecting positive direction acceleration, detection electrodes 150 and 151 for detecting negative direction acceleration, and the like.

When the 3-axis inertial measurement system according to the present invention accelerates on the x-axis, the x-axis accelerometer 100 also accelerates on the x-axis. At this time, the position of the internal mass 110 is changed, and the capacitance between the internal mass 110 and the detection electrodes 140, 141, 150, and 151 is changed by the displacement of the internal mass 110. The change in capacitance is detected by an external capacitance detector (not shown) to detect the x-axis translation of the internal mass. The capacitance detector includes a capacitance-voltage converter, and converts the capacitance change into a voltage value and outputs the converted voltage.

The structure and principle of the accelerometer are described in Ko, H., Kim, J., Park, S., Kwak, D., Song, T., Setiadi, D., Carr, W., Buss, J., and Cho, D., "A High-performance X / Y-axis Microaccelerometer Fabricated on SOI Wafer without Footing Using the Sacrificial Bulk Micromachining (SBM) Process," 2003 International Conference on Control, Automation and Systems (ICCAS 2003), pp. 2187-2191, Gyeongju, Korea, Oct. 2003, the detailed description of the micro-accelerometer will be omitted.

The y-axis accelerometer 101 rotates the x-axis accelerometer 100 by 90 ° on the same plane so as to detect the acceleration motion of the y-axis. The rest of the configuration is the same as that of the x-axis accelerometer 100.

As shown in the drawing, the z-axis angular tachometer 200 includes a driving mass 210 capable of oscillating in the left and right directions, a sensing mass 215 capable of oscillating in the up and down directions, and a ground grounded as a reference voltage. Positive direction for detecting vibrations of the electrode 120, the positive direction driving electrodes 230 and 231 and the negative direction driving electrodes 235 and 236 and the driving mass 210 to vibrate the driving mass 210. The driving test electrode 233 and the negative direction driving test electrode 237, the detection electrode 240 for detecting the positive angular velocity of the detection mass 215, the detection electrode 250 for detecting the negative angular velocity, and the like. It includes.

When the angular tachometer 200 rotates about the z axis while the driving mass 210 vibrates in the left and right directions (ie, the y axis), the detection mass 215 is perpendicular to the driving direction. Coriolis power. Therefore, the detection mass 215 vibrates in the up and down direction (ie, the x axis) with respect to the vibration direction of the driving mass 210. As such, when the angular tachometer 200 rotates, the position of the detection mass 215 is changed, and between the detection mass 215 and the detection electrodes 240 and 250 by the displacement of the detection mass 215. The capacitance of will change. The change in capacitance is detected by an external capacitance detector (not shown) to detect the rotational movement of the angular speedometer 200. The capacitance detector includes a capacitance-voltage converter, and converts the capacitance change into a voltage value and outputs the converted voltage. Therefore, the angular velocity (that is, the rotational speed with reference to the z-axis) can be measured using the z-axis angometer.

The structure and principle of the angular velocity meter are described in Lee, S., Park, S., Kim, J., Lee, S., and Cho, D., "Surface / Bulk Micromachined Single-crystalline Silicon Micro-gyroscope," IEEE / ASME Journal of Microelectromechanical Systems, vol. 9, no. 4, pp. 557-567, Dec. 2000, the detailed description of the microangular rate meter is omitted herein.

As used herein, the terms “positive direction” and “negative direction” are concepts for distinguishing the direction of movement of the accelerometer or angular meter (eg, forward / reverse, clockwise / counterclockwise).

Hereinafter will be described a method for manufacturing a three-axis inertial measurement system according to the present invention. The three-axis inertial measurement system according to the present invention can be manufactured by forming the x-axis accelerometer, the y-axis accelerometer, and the z-axis angometer in the same plane of the same substrate by a sacrificial bulk micromachining (SBM) process.

3A to 3F are cross-sectional views illustrating a process of manufacturing a 3-axis inertial measurement system according to the present invention on an SOI substrate.

First, an etching mask layer 320 is patterned on an SOI substrate 310 including single crystal silicon 312 and 314 and an insulating layer 316. Thereafter, the substrate 310 is etched to a predetermined depth by using the etching mask layer 320 (FIG. 3A). At this time, the step (thickness) of the microstructure (390 in FIG. 3F) floating from the bottom surface, such as the internal mass, is determined by the depth to be etched.

Subsequently, an insulating film is formed as the passivation layer 330 on the entire surface of the substrate, including the trench 380 formed by the etching (FIG. 3B).

Thereafter, the protective film existing on the top surface of the substrate and the bottom surface of the trench 380 is etched and removed (FIG. 3C). Therefore, the sidewalls of the trench 380 may be protected by the passivation layer 330.

Thereafter, the substrate 310 is further etched using the etching mask layer 320 and the passivation layer 330 to expose the insulating layer 316 of the SOI substrate 310 (FIG. 3D).

Thereafter, the substrate 310 is wet-etched with, for example, an aqueous alkali solution to form a cavity 370 on the bottom surface of the additionally etched trench 380. By forming the cavity 370 as described above, the microstructure 390 having a predetermined thickness is suspended from the bottom surface (FIG. 3E).

Thereafter, the sidewall passivation layer 330, the etching mask 320, and the insulating layer 316 on the bottom are removed (FIG. 3F).

Through this process, the microstructure 390 may be formed by floating from the bottom surface.

4A to 4L are cross-sectional views illustrating a process of fabricating a three-axis inertial measurement system according to the present invention on a single crystal silicon substrate.

First, the etch mask layer 425 is deposited on the single crystal silicon substrate 410, the etch mask 425 of the portion 440 on which the electrode is formed is patterned, and the substrate 410 is etched (FIG. 4A). .

Thereafter, a protective film (insulation film) 435 is deposited on sidewalls and top surfaces of the substrate (FIG. 4B).

Thereafter, the protective film 435 of the trench bottom surface of the substrate is etched so that the protective film 435 exists only on the sidewall (FIG. 4C).

Thereafter, the substrate 410 is wet-etched to etch portions of the sidewalls without the protective film 435 (FIG. 4D).

Thereafter, the etching mask layer 425 and the protective layer 435 are removed (FIG. 4E).

Thereafter, the sidewalls and the portions etched from the sidewalls are embedded with an insulator 450 (FIG. 4F). Accordingly, the portion where the electrode is formed and the silicon substrate 410 may be insulated from each other.

Thereafter, the process of forming the microstructure (490 of FIG. 4L) on the substrate 410 is similar to the process of FIGS. 3A to 3F.

That is, the etching mask layer 420 is patterned on the single crystal silicon substrate 410. Thereafter, the substrate 410 is etched to a predetermined depth by using the etching mask layer 420 (FIG. 4G). At this time, the level of the microstructure (490 of FIG. 4L) floating from the bottom surface, such as the internal mass, is determined by the depth to be etched.

Thereafter, the protective layer 430 is formed on the entire surface of the substrate, including the trench 480 formed by the etching (FIG. 4H).

Thereafter, the protective film existing on the upper surface of the substrate and the bottom surface of the trench 480 is etched and removed (FIG. 4I). Therefore, the sidewalls 480 of the trench may be protected by the passivation layer 430.

Thereafter, the substrate 410 is further etched to a predetermined depth by using the etching mask layer 420 and the passivation layer 430 (FIG. 4J).

Thereafter, the substrate 410 is wet-etched with, for example, an aqueous alkali solution to form a cavity 470 on the bottom surface of the additionally etched trench 480. By forming the cavity 470 in this manner, the microstructure 490 having a predetermined thickness is suspended from the bottom surface (FIG. 4K).

Thereafter, the sidewall passivation layer 430 and the etching mask 420 are removed (FIG. 4L).

Through this process, the microstructure 490 may be formed by floating from the bottom surface.

5A to 5F are cross-sectional views illustrating a process of manufacturing a triaxial inertial measurement system according to the present invention on an SOG substrate bonded to a silicon substrate and a glass substrate. The process of forming the microstructure on the substrate is also similar to the process of FIGS. 3A to 3F described above.

First, the silicon substrate 512 and the glass substrate 514 are bonded to form an SOG substrate 510, and then an etching mask layer 520 is patterned on the SOG substrate 510. Thereafter, the substrate 510 is etched to a predetermined depth by using the etching mask layer 520 (FIG. 5A). At this time, the level of the microstructure (590 of FIG. 5F) floating from the bottom surface, such as the internal mass, is determined by the depth to be etched.

Thereafter, the protective layer 530 is formed on the entire surface of the substrate, including the trench 580 formed by the etching (FIG. 5B).

Thereafter, the protective film existing on the top surface of the substrate and the bottom surface of the trench 580 is etched and removed (FIG. 5C). Therefore, the passivation layer 530 is present only on the sidewalls of the trench 580.

Subsequently, the substrate 510 is further etched using the etching mask layer 520 and the protective layer 530 to expose the glass substrate 514 of the substrate 510 (FIG. 5D).

Thereafter, the substrate 510 is wet-etched with, for example, an aqueous alkali solution to form a cavity 570 on the bottom surface of the additionally etched trench 580. By forming the cavity 570 in this way, the microstructure 590 having a predetermined thickness is suspended from the bottom surface (FIG. 5E).

Thereafter, the sidewall passivation layer 530 and the etching mask 520 are removed (FIG. 5F).

Through this process, the microstructure 590 may be formed by floating from the bottom surface.

In the 3-axis inertial measurement system manufactured by the SBM technology according to the present invention, the accelerometer and the angular meter, which are inertial sensors for each axis, are the same substrate regardless of the type of the substrate (SOI substrate, general substrate, or SOG substrate). Is formed simultaneously. Thus, no alignment error occurs between the three axes. In addition, the packaging process is simpler than the conventional assembly method, yield is increased, and the size of the manufactured inertial sensor can be minimized.

Claims (5)

A three-axis inertial measurement system having an x-axis accelerometer for detecting the x-axis translational motion, a y-axis accelerometer for detecting the y-axis translational motion, and a z-axis angular speedometer for detecting the z-axis rotational motion on a single substrate. The three-axis inertial measurement system according to claim 1, wherein the x-axis accelerometer, the y-axis accelerometer, and the z-axis angometer are formed on the same plane. The system of claim 1, wherein the single substrate is a single crystal silicon substrate, an SOI substrate, or a silicon-on-glass substrate. The three-axis inertial measurement system of claim 1, wherein the x-axis accelerometer, the y-axis accelerometer, and the z-axis accelerometer are formed by a sacrificial bulk micromachining (SBM) process. The three-axis inertial measurement system of claim 1, wherein the accelerometer or the angular velocity detector detects acceleration or angular velocity by detecting a change in capacitance between an internal mass and a detection electrode during a translational or rotational movement.

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