KR19990039351A - High Sensitivity Circuit Integrated Micro Gyroscope and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a microgyroscope for detecting an inertial angular velocity of an object, and a method of manufacturing the same, wherein a signal sensing circuit and a microgyroscope structure are integrated in a direction perpendicular to the substrate on a single substrate by combining micromachining technology and IC technology. By integrating, the micro gyroscope structure and the signal sensing circuit are combined without any external wiring as well as minimizing the size of the device, thereby fundamentally blocking the noise inflow path.

Description

High Sensitivity Circuit Integrated Micro Gyroscope and Manufacturing Method Thereof

The present invention relates to a micro gyroscope for detecting an inertial angular velocity of an object and a method of manufacturing the same. Specifically, a micro gyroscope and an IC technology are integrated by combining a micro gyroscope and a signal sensing circuit to substantially reduce the effects of noise. The present invention relates to a highly sensitive circuit-integrated microgyroscope that does not receive and a method of manufacturing the same.

1 is a vertical cross-sectional view of a conventional standalone microgyroscope. As shown, the stand-alone microgyroscope has an anchor portion 12 formed of primary polysilicon on a silicon substrate 15 on which a Si ₃ N ₄ insulating layer 14 and a SiO ₂ insulating layer 3 are sequentially applied. And a movable structure 11 formed of secondary polysilicon so as to be engaged with it. Such a standalone microgyroscope requires wiring between the external circuit and the microgyroscope because signal processing is performed in an external circuit. Therefore, such a structure has a problem of unprotected exposure to noise inflow through the wiring.

2 is a conventional circuit integrated micro sensor. As shown, the conventional single micro acceleration sensor and the signal processing circuit are integrated in the horizontal direction on the same substrate. That is, one substrate includes a DAC circuit region 17, an ECL to CMOS circuit region 18, a LATCH circuit region 19, a preamp circuit region 20, an integrator circuit region 22, and the like. Is divided into a circuit area and a micro sensor area (16, 21). This structure reduces the noise significantly due to the shorter wiring than the stand-alone type, but has a big limitation in reducing the area of the sensor system as it is integrated horizontally with respect to the substrate. In addition, the unit of the signal detected by the micro-sensor is about femto farad (fF, that is, ^10-15 F), whereas the capacitance between the wirings 23 connecting the circuits integrated on the substrate is about femto farad. There are many cases where the micro-sensor signal cannot be distinguished from the noise flowing along the wiring.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a high-sensitivity circuit-integrated microgyroscope with a high signal sensitivity and an integrated density of devices by eliminating wiring between the microgyroscope and its signal processing circuits. have.

1 is a cross-sectional view of a conventional gyroscope not integrated circuit,

2 is a plan view of a conventional circuit-integrated micro gyroscope,

3A and 3B are respectively a perspective plan view of a high sensitivity circuit integrated microgyroscope according to the present invention;

3A is a perspective plan view of a depletion mode MOSFET integrated microgyroscope,

3B is a perspective plan view of an enhancement mode MOSFET integrated microgyroscope,

4 is a vertical cross-sectional view of the circuit integrated microgyroscope of FIG. 3A;

5A to 5G are vertical cross-sectional views after a step-by-step process of fabricating the highly sensitive integrated microgyroscope of FIG. 3A.

5A and 5B illustrate a manufacturing process of a signal sensing FET, FIG. 5A is a vertical cross-sectional view after a diffusion or implantation process for operating a MOSFET in a depletion mode, and FIG. 5B illustrates drain and source layer formation. Vertical cross-sectional view after the diffusion or implantation process for

5C to 5F are vertical cross-sectional views after a step-by-step process of manufacturing a pure microgyroscope.

<Description of Symbols for Main Parts of Drawings>

1. Silicon Substrate 2. MOSFET Active Area

3. drain and source area of MOSFET 4. polysilicon moving plate

5. Polysilicon anchor plate 6.Polysilicon anchor plate

7.PSG Sacrificial Layer

8. Poly silicone

9. PSG (for polysilicon doping and polysilicon etch mask)

10.SiO ₂ 11.Secondary Poly Silicon

12. Primary polysilicon 13. SiO ₂

14.Si ₃ N ₄ 15. Silicon substrate

16.Micro Sensor Area 17.DAC Circuit Area

18. ECL to CMOS Circuit Area 19. LATCH Circuit Area

20. Preamp circuit area 21. Micro sensor area

22. Integrator Circuit Area

In order to achieve the above object, a high-sensitivity circuit integrated microgyroscope according to the present invention includes a high sensitivity circuit including a micro gyroscope having a movable structure and a signal processing circuit for processing signals generated by the micro gyroscope. In the integrated microgyroscope, the microgyroscope and the signal processing circuit are arranged so as to overlap up and down.

In the present invention, it is preferable that the movable structure is disposed directly above a channel of the input terminal transistor such that the movable structure is used as an input transistor gate of the signal processing circuit, and the transistor has a capacitance corresponding to an amount of position change by the angular velocity of the movable structure. It is desirable to detect the change as a conversion amount of current or voltage.

In order to achieve the above object, a method of manufacturing a high-sensitivity circuit integrated microgyroscope according to the present invention includes the steps of: (a) forming an active region for a transistor by doping a first impurity on a silicon substrate; (B) forming an insulating layer having a predetermined pattern on the substrate on which the active region is formed, and forming a source and a drain region by doping a second impurity in the active region using the insulating layer as a mask; (C) forming a sacrificial layer having a predetermined thickness on the substrate on which the source and drain are formed; (D) forming openings in the sacrificial layer for forming anchors of the microgyroscope; (E) depositing a polysilicon layer to form a fixed plate and a movable plate of a microgyroscope on the sacrificial layer and the insulating layer exposed by the opening; (F) forming a mask on the polysilicon layer and then etching the polysilicon layer to form the fixed plate and the movable plate; And (g) etching and removing the mask on the sacrificial layer and the polysilicon layer.

In the present invention, the step (a) may include a sub-step of forming a mask by depositing and etching silicon dioxide on the silicon substrate; And a sub step of doping the first impurity using the mask. In the step (b), the insulating layer is formed of silicon dioxide, and in the step (c), the sacrificial layer is formed of PSG. In the step (bar), the mask is preferably formed of PSG.

Hereinafter, a high-sensitivity circuit integrated microgyroscope and a manufacturing method thereof according to the present invention will be described with reference to the accompanying drawings.

The high-sensitivity circuit integrated microgyroscope according to the present invention has a structure in which the input terminal FETs of the signal sensing circuit of the microgyroscope structure and the microgyroscope structure are vertically integrated on a single substrate. This will be described with reference to Examples.

3A and 3B are respectively a perspective plan view of a high sensitivity circuit integrated micro gyroscope according to the present invention, respectively, of a depletion mode MOSFET integrated micro gyroscope and an enhancement mode MOSFET integrated micro gyroscope, respectively. A perspective plan view is shown. As shown, the high-sensitivity circuit-integrated microgyroscope according to the present invention is doped with a first impurity in the silicon substrate 1 to form the active region 2 for the MOSFET and doped with a second impurity in the source 3a. ) And a drain 3b to form a conduction channel therebetween (in the depletion mode), or insert a conduction channel and doping a second impurity on both sides to form the source 3c and the drain 3d. Next, in the case of the reinforcement mode, the movable plate 4 and the fixed plate 5, 6 are formed on both sides of the movable plate 4 with polysilicon 4, 5, 6 on the upper side thereof. . To examine this in more detail, a vertical cross-sectional view of the depletion mode MOSFET integrated microgyroscope of FIG. 3A taken along the line A-A 'is shown in FIG. 4.

That is, referring to FIG. 4, in the depletion mode MOSFET integrated microgyroscope, an active region 2 (p-well) is formed by doping a p-type first impurity into the silicon substrate 1, and an n ⁺ type inside thereof. Dopants are doped to form a source 3a and a drain 3b (wherein, when the first impurity is n-type, the second impurity is p ⁺ -type), and SiO ₂ is formed as an insulating layer thereon. 10 is stacked, and a movable plate 4 of a microgyroscope is formed as a gate thereon, and fixed plates 5 and 6 are formed at the same time. As described above, in the high-sensitivity circuit integrated microgyroscope according to the present invention, the microgyroscope and its signal processing circuit are disposed so as to overlap up and down, and the movable plate 4 of the microscope is used as the gate of the input terminal transistor of the signal processing circuit. It is characterized by being formed just above the channel of the input transistor. Therefore, the input terminal transistor detects the change in capacitance corresponding to the position change amount due to the angular velocity of the movable plate 4 as a change amount of current or voltage and detects the angular velocity, thus having high sensitivity. Since this structure does not require any wiring at all, there is an advantage that the influence of external noise can be suppressed to the maximum. That is, the operating principle of the circuit-integrated micro gyroscope is that when the movable plate 4 vibrates in the vertical direction due to the Coliolis force, the capacitance between the movable plate 4 and the conduction channel of the FET changes. Since the electrical conductivity of the conducting channel of the lower FET varies, the current flowing through the channel of the FET changes. Since the magnitude of this current is proportional to the vibration displacement of the structure, the magnitude and direction of the angular velocity can be detected from the magnitude of this current.

On the other hand, the manufacturing method of the high-sensitivity circuit-integrated microgyroscope with the above structure is as follows.

First, as shown in FIG. 5A, a first impurity (p-type or n-type impurity) is doped on the silicon substrate 1 to form the active region 2 for the transistor. This step is accomplished by depositing and etching silicon dioxide on the silicon substrate 1 to form a mask 10 and then doping the first impurities using the mask 10.

Next, as shown in FIG. 5B, silicon dioxide is deposited on the substrate 1 on which the active region 2 is formed to form an insulating layer, and the insulating layer is patterned to form a mask 10 ′. The source 3a and the drain 3b are formed by doping the second impurity (n ⁺ type or p ⁺ ) into the active region 2 using the mask 10 '.

Next, as shown in FIG. 5C, a sacrificial layer 7 having a predetermined thickness is formed on the substrate 1 on which the source 3a and the drain 3b are formed. This sacrificial layer 7 is formed of PSG.

Next, as shown in FIG. 5D, the openings 7a and 7b for forming the fixing plates (anchors) of the microgyroscope are formed in the sacrificial layer 7, and then the sacrificial layer 7 and the openings 7a and 7b are formed. The polysilicon layer 8 and the PSG layer 9, which will form the stationary plate and the movable plate of the microgyroscope, are sequentially deposited on the insulating layer 10 'exposed by the &lt; RTI ID = 0.0 &gt;

Next, as shown in FIG. 5E, the PSG layer 9 is patterned to form a mask 9 ′, and then the polysilicon layer 8 is etched to fix the microgyroscopic fixing plates 5 and 6 and move. The plate 4 is formed.

Next, as shown in FIG. 5F, the sacrificial layer 7 and the mask 9 ′ on the polysilicon layer are etched away to complete a high sensitivity circuit integrated microgyroscope.

As described above, the circuit-integrated microgyroscope according to the present invention has a circuit fabricated in a standard integrated circuit process on a lower substrate, and a microstructure is fabricated in a standard micromachining process thereon.

As described above, the high-sensitivity circuit-integrated microgyroscope according to the present invention integrates micromachining technology and IC technology and integrates a microgyroscope and a signal sensing circuit together in a high vacuum package, thereby having the following advantages.

1) By integrating signal processing IC circuit in the vertical direction of the lower substrate of the micro gyroscope structure, the cost saving effect is greatly increased due to the smallest area of the device.

2) By integrating signal processing IC circuits vertically on the lower substrate of the micro gyroscope structure, single chip integration is realized in a standard process without modification of the structure fabrication process or the integrated circuit fabrication process.

3) The manufacturing process is easier and simpler than the prior art, which can speed up the time of commercialization.

Claims (8)

A high sensitivity circuit-integrated microgyroscope having a microgyroscope having a movable structure and a signal processing circuit for processing signals generated by the microgyroscope, And the microgyroscope and the signal processing circuit are arranged so as to overlap up and down. The method of claim 1, And the movable structure is disposed directly above a channel of the input transistor so that the movable structure is used as an input transistor gate of the signal processing circuit. The method of claim 2, And the transistor detects a capacitance change corresponding to the position change amount due to the angular velocity of the movable structure as a change amount of current or voltage. (A) doping the first impurity on the silicon substrate to create an active region for the transistor; (B) forming an insulating layer having a predetermined pattern on the substrate on which the active region is formed, and forming a source and a drain region by doping a second impurity in the active region using the insulating layer as a mask; (C) forming a sacrificial layer having a predetermined thickness on the substrate on which the source and drain are formed; (D) forming openings in the sacrificial layer for forming anchors of the microgyroscope; (E) depositing a polysilicon layer to form a fixed plate and a movable plate of a microgyroscope on the sacrificial layer and the insulating layer exposed by the opening; (F) forming a mask on the polysilicon layer and then etching the polysilicon layer to form the fixed plate and the movable plate; And (G) etching and removing the mask on the sacrificial layer and the polysilicon layer; A method of manufacturing a high sensitivity circuit integrated microgyroscope, comprising: The method of claim 4, wherein Step (a), Depositing and etching silicon dioxide on the silicon substrate to form a mask; And Sub-doping a first impurity using the mask; A method of manufacturing a high sensitivity circuit integrated microgyroscope, comprising: The method of claim 4, wherein In the step (b), wherein the insulating layer is formed of silicon dioxide. The method of claim 4, wherein In the step (c), the sacrificial layer is formed of PSG. The method according to claim 4 or 7, And in the step (f), the mask is formed of PSG.