KR101064285B1 - Single-axis acceleration detection element and sensor using the same - Google Patents

Abstract

The present invention relates to a single-axis acceleration measuring device and an acceleration measuring sensor using the same. The uniaxial accelerating device and sensor formed of a mechanical structure cannot be used for small components due to their large size, and are formed by a micromachining method. In order to solve the problem that the manufacturing method is complicated and difficult, relates to a uniaxial acceleration measuring device and sensor having a simple structure that can be easily processed using a general process of forming a semiconductor device.

Description

Single-axis acceleration measuring device and acceleration measuring sensor using same {SINGLE-AXIS ACCELERATION DETECTION ELEMENT AND SENSOR USING THE SAME}

1 is a plan view showing a uniaxial acceleration measuring device according to the present invention.

FIG. 2 is a cross sectional view taken along line AA ′ of FIG. 1; FIG.

FIG. 3 is a cross-sectional view taken along the line BB ′ of FIG. 1. FIG.

4 is a schematic diagram illustrating an acceleration measurement sensor according to the present invention.

The present invention relates to a uniaxial acceleration measuring device and an acceleration measuring sensor using the same. The uniaxial acceleration measuring device and sensor formed of a mechanical structure cannot be used for small components due to their large size, and are formed by a micro machining method. In order to solve the problem that the fabrication method is complicated and difficult, the present invention relates to a uniaxial acceleration measuring device and a sensor having a simple structure that can be easily processed using a general process of forming a semiconductor device.

Uniaxial accelerometers are devices that are used in all parts of the industry such as automotive airbags. The uniaxial acceleration sensor consists of a component that recognizes physical motion and a circuit that converts it into an electrical signal.

Since the uniaxial acceleration measuring device according to the prior art is formed of a mechanical structure and bulky, and a separate circuit part must be added, its configuration and forming process are complicated. In addition, there is a limitation in detecting the response to the fine signal and there is a disadvantage in that the reaction speed is also slow.

Therefore, the method of manufacturing the uniaxial acceleration sensor using a microfabrication technique is used, but there are many limitations due to the difficulty in performing a precise process.

In order to solve the problems as described above, the present invention forms a fine acceleration measurement device using a semiconductor device process. The acceleration element may be formed to form a mass part and a movable part capable of recognizing an operation in a single flat plate structure to serve as an electrode of a capacitor, thereby manufacturing an acceleration measurement sensor without configuring a separate complicated circuit.

The present invention is to achieve the above object, the uniaxial acceleration measuring device according to the present invention

A first mass part of the rhombus;

A rhombic movable part provided along an outer edge of the first mass part and sharing one vertex with the first vertex of the first mass part;

A second mass part connected to a first vertex of the movable part;

A fixing part connected to a third vertex facing the first vertex of the movable part and attached to a semiconductor substrate; And

And a line type capacitor electrode connected to each of the second and fourth vertices of the movable part in a flat structure.

In addition, the uniaxial acceleration measurement sensor according to the present invention

First, second, and third uniaxial acceleration measurement elements of a plate structure; And

A reference capacitor connected to a lower portion of the second uniaxial acceleration measuring element and a second electrode connected to the lower fixed portions of the first and third uniaxial acceleration measuring elements on both sides of the second uniaxial acceleration measuring element; ,

The first, second and third uniaxial acceleration measuring elements are respectively

A first mass part of the rhombus;

A rhombic movable part provided along an outer edge of the first mass part and sharing one vertex with the first vertex of the first mass part;

A second mass part connected to a first vertex of the movable part;

A fixing part connected to a third vertex facing the first vertex of the movable part and attached to a semiconductor substrate; And

Line type capacitor electrodes connected to the second and fourth vertices of the movable part, respectively.

Equipped with

The first, second and third uniaxial acceleration measuring elements are arranged on the same plane so that the linear capacitor electrodes face each other.

Hereinafter, the uniaxial acceleration measuring device and the uniaxial acceleration measuring sensor formed using the same will be described in detail with reference to the accompanying drawings.

1 is a plan view illustrating a uniaxial acceleration measuring device according to the present invention.

Referring to FIG. 1, the uniaxial acceleration measuring element of the flat plate structure according to the present invention includes a rhombus first mass part 110, a rhombus movable part 100, a second mass part 120, and a semiconductor substrate. A uniaxial acceleration measurement element having a fixed portion 130 and a line type capacitor electrode 140 attached to (not shown) in a planar structure is shown. Here, the movable part 100 is provided along the outer periphery of the first mass part 110, and the second mass part 120 shares one vertex with the first vertex of the first mass part and the first of the movable part 100. Connected to the vertex. In addition, the fixing part 130 is connected to the third vertex opposite to the first vertex of the movable part 100 and the line type capacitor electrode 140 is connected to the second and fourth vertices of the movable part 100, respectively. The fixing unit 130 includes a support 135 for fixing the uniaxial acceleration measurement element to the lower semiconductor substrate.

In addition, the first and second mass parts 110 and 120 may include at least one or more openings. This is to form the sacrificial oxide layer in order to smoothly etch the sacrificial oxide layer in the process of forming the uniaxial acceleration measurement element. Therefore, according to the use of the acceleration measuring element of the mass part, a predetermined mass material may be further provided on the first and second mass parts 110 and 120, respectively.

In the above method of forming the uniaxial acceleration measurement element, first, a planarized sacrificial oxide layer is formed on a semiconductor substrate, and a contact hole is formed in the sacrificial oxide layer to form a support in the region where the fixed portion of the uniaxial acceleration measurement element is to be formed. At this time, it is preferable to etch a predetermined depth so that the semiconductor substrate is not exposed.

Next, a conductive polysilicon layer or a metal layer is formed on the sacrificial oxide layer, and the sacrificial oxide layer below the first and second mass parts is removed by a wet etching process using a mask having a shape as shown in FIG. 1. do. At this time, the etching solution flows into the openings provided in the regions where the first and second mass parts are to be formed so that the sacrificial oxide layer underneath can be completely removed.

Here, the support is naturally formed while the polysilicon layer or the metal layer is filled in the contact hole formed in the sacrificial oxide layer, and the sacrificial oxide layer between the support and the semiconductor substrate is not completely removed in the wet etching process so that the support remains in the semiconductor substrate. To be fixed to the

The acceleration measuring element formed as described above has a line connected to the second and fourth vertices while the lengths of the diagonals with respect to the first and third vertices of the movable portion increase or decrease when a force is applied to the first and second mass portions. The spacing between the capacitor capacitor and the capacitor electrode of the adjacent acceleration measurement elements is changed.

FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1.

Referring to FIG. 2, a state in which the second mass part 120 and the linear capacitor electrode 140 are suspended in the air is disposed on the semiconductor substrate 150. Although it is preferable that all of the lower sacrificial oxide layer 115 is removed by wet etching, some residual material may remain, but this does not affect the operation of the acceleration measuring device according to the present invention.

3 is a cross-sectional view illustrating a cross section taken along line BB ′ of FIG. 1.

Referring to FIG. 3, the fixing part 130 is fixed to the semiconductor substrate 150 by the remaining sacrificial oxide layer 115 and the support 135. Since the first and second mass parts (not shown) include openings, all of the lower sacrificial oxide layers are removed in the wet etching process. However, since the fixing part 130 does not have openings, the lower sacrificial oxide layers 115 are not included. This is not removed and remains. In this case, the sacrificial oxide layer 115 is combined with the support 135 of the fixing part 130 to fix the semiconductor layer 150 to the semiconductor substrate 150. An acceleration measurement including the fixing part 130 from the semiconductor substrate 150 is performed. It serves to electrically insulate the line capacitor electrode 140 of the device.

Figure 4 is a schematic diagram showing a flat acceleration sensor using the acceleration measurement device of Figure 1 according to the present invention.

Referring to FIG. 4, the linear capacitor electrodes 140 of the first, second and third uniaxial acceleration measurement elements of the plate structure are arranged in a line on the same plane so as to face each other. Here, when the uniaxial acceleration measurement element located at the center is called the second uniaxial acceleration measurement element, those located at both sides become the first or third uniaxial acceleration measurement element, respectively. In this case, one electrode of the reference capacitor 160 is connected to the fixing unit 130 of the second uniaxial acceleration measurement element, and the other electrode is simultaneously connected to the first and third uniaxial acceleration measurement elements.

In the above structure, each of the first, second and third uniaxial acceleration measuring elements serves as one capacitor electrode. Accordingly, a change occurs in the spacing between the linear capacitor electrodes 140 facing each other according to the expansion and contraction of each acceleration measuring element, and a change occurs in the capacitance value. The uniaxial acceleration measurement sensor according to the present invention can measure the acceleration by measuring the change amount of the capacitance value and comparing it with a reference capacitor.

In addition, the uniaxial acceleration measurement sensor according to the present invention can be easily manufactured by using a general semiconductor process, such as a method of wet etching the sacrificial oxide layer, as well as vibration and shock detection devices for trains or automobiles, as well as sensors for protecting hard disks. It can be easily applied to sensors that require fine size.

As described above, the uniaxial acceleration measuring device and the sensor according to the present invention have a finer size, a simpler forming process, and a higher reaction speed than the sensor used as a mechanical structure.

It will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible, and that various modifications, additions and substitutions are possible, within the spirit and scope of the appended claims. As shown in Fig.

Claims (4)

A first mass part of the rhombus; A rhombic movable part provided along an outer edge of the first mass part and sharing one vertex with the first vertex of the first mass part; A second mass part connected to a first vertex of the movable part; A fixing part connected to a third vertex facing the first vertex of the movable part and attached to a semiconductor substrate; And And a linear capacitor electrode connected to the second and fourth vertices of the movable portion, respectively. First, second, and third uniaxial acceleration measurement elements of a plate structure; And A reference capacitor connected to a lower portion of the second uniaxial acceleration measuring element and a second electrode connected to the lower fixed portions of the first and third uniaxial acceleration measuring elements on both sides of the second uniaxial acceleration measuring element; , The first, second and third uniaxial acceleration measuring elements are respectively A first mass part of the rhombus; A rhombic movable part provided along an outer edge of the first mass part and sharing one vertex with the first vertex of the first mass part; A second mass part connected to a first vertex of the movable part; A fixing part connected to a third vertex facing the first vertex of the movable part and attached to a semiconductor substrate; And A line capacitor electrode connected to the second and fourth vertices of the movable part, respectively, And said first, second and third uniaxial acceleration measurement elements are arranged on the same plane such that the linear capacitor electrodes face each other. The method of claim 2, And the first and second mass parts include at least one or more openings. The method of claim 2, The fixed part uniaxial acceleration measurement sensor, characterized in that it comprises a support connected to the lower semiconductor substrate.

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