JPH10104262A - Semiconductor acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the bonding strength between a stopper and a support part by fixing the stopper by a wiring part formed of aluminum. SOLUTION: A first stopper 5 is fixed to one surface side of a support part 4 in the state closely fitted to each of a wiring part 7 formed of aluminum thin film, a fixing part and a bonding part 43 formed by evaporation or sputtering without providing a diffusion window in a silicon oxide film 44, and bonded to the support part 4. When an acceleration is applied to a weight part 1, a distortion part 2 is distorted, and a piezo resistor is also distorted to convert the acceleration into an electric signal. The weight part 1 makes contact with the first contact surface 51 of the first stopper in the application of an excessive acceleration, and with the second contact surface 61 of a second stopper 6 in case of the reverse acceleration. Namely, the first and second stoppers 5, 6 prevent the distortion of the distortion part 2 from being a prescribed value or more. The first stopper 5 has a high bonding strength with the support part 4 and is never peeled therefrom since it is closely fixed to not only the bonding part 43 but also the wiring part 7 and the fixing part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor acceleration sensor used for automobiles, home electric appliances and the like.

[0002]

2. Description of the Related Art Conventionally, there is a semiconductor acceleration sensor of this type having a configuration shown in FIG. This device converts the acceleration into an electric signal based on the weight portion A, a bending portion B having one end connected to the weight portion A so that the weight portion A bends when acceleration is applied thereto, and the bending of the bending portion B. A sensor portion C formed in the flexible portion B and a plurality of electrode pads D1 connected to the terminals are provided on one surface side, and the outer peripheral edge of the weight portion A is provided and surrounded by a space D2, and the other end of the flexible portion B is provided. And a stopper fixed to a joining portion D3 formed on one surface side of the supporting portion D and having a contact surface with which the weight portion A can contact, and one surface side of the supporting portion D Both ends are sensor part C
And a plurality of wiring portions F respectively connected to the electrode pads D1.

More specifically, the wiring portion F is formed of a P-type diffusion layer in which boron is diffused in a silicon semiconductor, has a higher specific resistance than metal, and has an electric signal obtained by converting acceleration from the sensor portion C. Is attenuated and the sensitivity deteriorates, so that the width of the diffusion layer is widened to reduce the wiring resistance.

The bonding portion D3 has a substantially rectangular support portion D in a state where the wiring portion F is covered with a thin film of aluminum.
Is formed on one side to fix the stopper. The stopper prevents the bending portion B from being broken by the weight portion A coming into contact with the contact surface when an excessive acceleration is applied.

[0005]

In the above-described conventional semiconductor acceleration sensor, when an excessive acceleration is applied, the stopper prevents the deflected portion B from being destroyed, and the sensor portion C detects the deflected portion B based on the deflected portion B. Thus, the acceleration can be detected by converting the acceleration into an electric signal.

However, since the wiring portion F is formed by a diffusion layer, a diffusion window is formed by removing a silicon oxide film of a silicon semiconductor, and then boron is diffused, the bonding portion D3 and the wiring portion F are formed. And a gap is formed between them so that they do not adhere to each other. Therefore, even if the stopper is fixed to the bonding portion D3, the connection between the bonding portion D3 and the wiring portion F is not fixed, so that there is a problem that the bonding strength with the supporting portion is eventually low.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor acceleration sensor having an improved bonding strength between a stopper and a support.

[0008]

According to a first aspect of the present invention, there is provided a flexure having a weight portion and a flexure having one end connected to the weight portion so that the weight portion flexes when acceleration is applied to the weight portion. A sensor unit formed on the flexure so as to convert the acceleration into an electric signal based on the flexure of the flexure,
A plurality of electrode pads to be connected to the terminals are provided on one side, and a supporting portion that supports the other end of the bending portion by providing a space around the outer peripheral edge of the weight portion and a contact surface where the weight portion can contact. A semiconductor having a stopper formed on one surface of the support portion and fixedly attached thereto, and a plurality of wiring portions having both ends connected to the sensor portion and the electrode pad on the one surface side of the support portion, respectively. In the acceleration sensor, the wiring portion wired with aluminum has a configuration in which the stopper is fixed.

According to a second aspect of the present invention, in the first aspect, a fixing portion for fixing the stopper is provided between the wiring portions in an island shape separated from the wiring portion. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 1 denotes a weight portion, which is formed in a substantially square shape by a thin silicon semiconductor, is cantilevered, and is displaced when acceleration is applied. Reference numeral 2 denotes a bending portion, which is formed by cutting the silicon semiconductor into a trapezoidal cross section from the other surface side with a thin silicon semiconductor, and having one end connected to the weight portion 1 so as to bend when an acceleration is applied to the weight portion 1. It is connected.

Reference numeral 3 denotes a sensor unit, and four sensor units 2 are formed by a piezoresistor made of a semiconductor so as to form a bridge circuit.
And converts the acceleration into an electric signal based on the bending of the bending portion 2 and outputs the electric signal.

Reference numeral 4 denotes a support portion, which is formed in a substantially rectangular shape by a thin silicon semiconductor and surrounds an outer peripheral edge of the weight portion 1 by providing a space 41 to support the other end of the bending portion 2. A plurality of electrode pads 42 that are wire-bonded to wires and connected to terminals (not shown) are provided on one surface side.
Further, two sets of joints 43 made of aluminum thin film
Are provided on one side with a substantially U-shaped pattern formed of a central portion 43a and both opposing portions 43b, and a plurality of printed resistors 44 are provided, which are used for balance adjustment of the bridge circuit of the sensor unit 3. .

Reference numeral 5 denotes a first stopper, which is formed in a substantially square shape by Pyrex glass, and has a first contact surface 51 at a substantially central portion with which the weight portion 1 can contact.
A gap 52 is formed between the weight 1 and the weight 1, and is joined to the support 4 on one surface side of the support 4. This will be described later in detail.

Reference numeral 6 denotes a second stopper, which is formed of a substantially square Pyrex glass and has a second contact surface 61 at a substantially central portion with which the weight portion 1 can contact.
A gap 62 is provided between the weight 1 and the weight 1, and is joined to the support 4 on the other surface side of the support 4.

Reference numeral 7 denotes a wiring portion, which is formed of a thin film of aluminum on the one surface side of the supporting portion 4 at a position opposite to the weight portion 1 with respect to the bending portion 2 without providing a diffusion window. It is formed along the central portion 43a and both opposing portions 43b of the support portion 4 by vapor deposition or sputtering, and both ends are connected to the sensor portion 3 and the electrode pad 42, respectively.

Reference numeral 8 denotes a fixing portion, which is provided between the wiring portions 7 and is separated from the wiring portions 7 by a thin film of aluminum, and a plurality of islands are provided on one surface side of the supporting portion 4.
5 along the central portion 43a and two along the opposite portions 43b, a total of 10 are formed by vapor deposition or sputtering without providing a diffusion window.

Here, the first stopper 5 is in close contact with each of the silicon oxide film 44 of the wiring portion 7, the fixing portion 8 and the bonding portion 43 without providing a diffusion window, without forming a gap. It is fixed on one surface side of the support portion 4,
It is joined to the support 4.

The operation of the above will be described. When an acceleration is applied to the weight 1, the weight 1 is displaced in a direction opposite to the direction in which the acceleration is applied, and the flexure 2 flexes, and the piezoresistor, which is the sensor unit 3 formed on one surface of the flexure 2, becomes When it is bent, the resistance value of the piezoresistor changes and converts the acceleration into an electric signal. Then, acceleration is detected by measuring a change in an electric signal output from both ends of the bridge circuit.

When an excessive acceleration is applied, the weight portion 1 is placed on the first contact surface 51 of the first stopper 5, and when an opposite acceleration is applied, the weight 1 is brought into contact with the second stopper 6 of the second stopper 6.
It contacts the contact surface 61. That is, the first stopper 5 and the second stopper 6 prevent the flexure of the flexure 2 from becoming a predetermined value or more, and prevent the flexure 2 from being damaged. At this time, since the first stopper 5 is fixed not only to the bonding portion 43 but also to the wiring portion 7 and the fixing portion 8, the first stopper 5 has a high bonding strength with the support portion 4 and does not peel off.

In this semiconductor acceleration sensor, as described above, since the wiring portion 7 wired with aluminum fixes the first stopper 5, the first stopper 5 is not only connected to the bonding portion 43 but also to the wiring portion 7. The first stopper 5 and the support portion 4 are fixed on one surface of the support
And the electric resistance from the sensor section 3 is transmitted to the electrode pad 42 without attenuating the electric signal from the sensor section 3 and the acceleration is highly sensitive. Can be detected.

Further, since the fixing portion 8 is separated from the wiring portion 7, that is, insulated and provided in an island shape between the wiring portions 7, the first stopper 5 is provided together with the bonding portion 43 and the wiring portion 7. However, the first stopper 5 and the support portion 4 are fixed.
And the gap between the wiring portions 7 between the first stopper 5 and the support portion 4 is reduced to prevent dust or moisture from entering, thereby preventing a short circuit between the wiring portions 7. be able to.

In this embodiment, the fixing portion 8 is provided between the wiring portions in an island shape, and the first stopper 5 is fixed. However, the bonding strength between the first stopper 5 and the support portion 4 is determined by the bonding strength between the wiring portion 7 and the bonding portion. When it can be secured only by the portion 43, the fixing portion 8 need not be provided, and there is no limitation.

In this embodiment, the second stopper 6 is provided and fixed to the other surface of the support portion 4. However, when there is no possibility that a reverse excessive acceleration is applied, the second stopper 6 is provided. It does not have to be and is not limited.

[0025]

According to the first aspect of the present invention, the stopper is fixed to the wiring portion 7 wired with aluminum.
The stopper is fixed to one side of the support part in a state of being in close contact with the wiring part as well as the joint part, so that the bonding strength between the stopper and the support part can be improved, and the wiring part can be compared with the conventional one. Since the specific resistance is low, the electric signal from the sensor unit can be transmitted to the electrode pad without attenuating, and the acceleration can be detected with high sensitivity.

According to the second aspect of the invention, in addition to the effect of the first aspect, the fixing portion is separated from the wiring portion, that is, insulated and provided in an island shape between the wiring portions.
By fixing the stopper with the fixing portion together with the joining portion and the wiring portion, the joining strength between the stopper and the supporting portion can be further improved, and the gap between the wiring portion between the stopper and the supporting portion is reduced, so that dust or moisture is reduced. Intrusion can be prevented, and a short circuit between the wiring portions can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a plan view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Weight part 2 Flexure part 3 Sensor part 4 Support part 41 Space 42 Electrode pad 43 Joining part 5 1st stopper 51 1st contact surface 7 Wiring part 8 Fixing part

Claims (2)

[Claims] A weight portion, a bending portion having one end connected to the weight portion to bend when acceleration is applied to the weight portion, and a bending portion for converting acceleration into an electric signal based on bending of the bending portion. The formed sensor portion, a plurality of electrode pads connected to the terminals are provided on one surface side, and a supporting portion that surrounds the outer peripheral edge of the weight portion with a space and supports the other end of the bending portion, A stopper having a contact surface that can be contacted and fixed to a joint formed on one surface of the support portion, and a plurality of wirings both ends of which are connected to the sensor portion and the electrode pad on one surface of the support portion, respectively. A semiconductor acceleration sensor comprising: a wiring portion wired with aluminum; and the stopper is fixed to the wiring portion. 2. The semiconductor acceleration sensor according to claim 1, wherein a fixing portion for fixing the stopper is provided between the wiring portions in an island shape separated from the wiring portion.