JPH0955515A - Manufacture of dynamical quantity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a dynamical quantity sensor wherein load is not applied to a flexible part. SOLUTION: An auxiliary substrate (fourth substrate) is bonded to a second substrate 2. Retaining members 21 and weight members 22 are cut out from the second substrate 2 to which the fourth substrate is bonded. A first substrate 1 is bonded to the second substrate 2, in the positional relation that a peripheral thick-walled part 15 is bonded to the retaining members 21, and a central thick- walled part 14 is bonded to the weight members 22 (c). The fourth substrate is removed from the second substrate 2 (d).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a manufacturing method for manufacturing a mechanical quantity sensor, particularly an acceleration sensor.

[0002]

2. Description of the Related Art Recently, a mechanical quantity sensor using a resistance element has been attracting attention, and in particular, an acceleration sensor for detecting the movement of an object has been actively developed.

A method of manufacturing the acceleration sensor is described in, for example, Japanese Patent Application Laid-Open No. 3-2535. Hereinafter, a conventional method for manufacturing an acceleration sensor, including this manufacturing method, will be briefly described.

First, the structure of a conventional acceleration sensor will be described with reference to FIG. As shown in the figure, the acceleration sensor is composed of three substrates, and the first substrate 1 includes an action portion (here, a thick center portion) 14 and a fixing portion (here, a peripheral thickness). 15) and a flexible part (here, thin part) 13 in which a plurality of resistance elements 11 are arranged at predetermined positions.
And The second substrate 2 is a single substrate at first, but a support for supporting the weight body 22 connected to the central thick portion 14 and the peripheral thick portion 15 by a separating step described later. It is separated into the body 21. Third substrate 3
Is a pedestal for restricting the movement of the weight body 22.

Then, as shown in FIG. 5, when a lateral acceleration is applied to the acceleration sensor, the weight 2
2 makes a rotational movement with the center of the upper surface of the central thick portion 14 as a reference, and the thin portion 13 is deformed accordingly. Each resistance element 11 embedded in the thin portion 13 changes its electrical resistance value according to the deformation. The acceleration sensor calculates the direction and magnitude of the acceleration by detecting the change in the electric resistance.

Further, as shown in FIG. 6, when vertical acceleration acts on the acceleration sensor, the weight body 22
Moves up and down, and the thin portion 13 is deformed accordingly.
The subsequent steps are as described above.

When excessive acceleration acts on the acceleration sensor, the movement of the weight body 22 is restricted by the first substrate 1 and the third substrate 3.

That is, with respect to the weight body 22, the first surface (hereinafter, the upper surface is referred to as the first surface and the lower surface is referred to as the second surface) is preliminarily scraped off to be thinner than the support body 21, As for the third substrate 3, a part of the first surface located below the weight body 22 is scraped off in advance. Further, the peripheral thick portion 15 slightly projects from the support 21 toward the center.

Therefore, the weight 22 has a thick peripheral portion 1
The first surface of itself contacts the second surface of 5, and the third substrate 3
The second surface of itself comes into contact with the first surface of the and its movement is restricted.

By limiting the movement of the weight body 22 in this manner, the thin portion 13 is not excessively deformed, so that the thin portion 13 can be prevented from being broken. Since the member strengths of the first substrate 1 and the third substrate 3 are relatively large, they will not be damaged by the contact of the weight body 22.

Next, a method of manufacturing the acceleration sensor will be described.

As shown in FIG. 7A, first, a plurality of resistance elements 11 are formed on the first surface of the first substrate 1 by an IC process.
Is formed at a predetermined position. Further, an etching mask 12 is formed on the second surface of the first substrate 1.

In FIG. 7B, the thin portion 13 is formed by etching the second surface of the first substrate. In FIG. 7C, the second substrate 2 having the cross-sectional shape as shown in FIG. 8 is bonded to the first substrate 1. In FIG. 7 (d), the bonded second
Dicing is performed from the second surface of the substrate 2 to cut out the weight body 22 and the support body 21. In FIG. 7E, the third substrate 3 is bonded to the second substrate 2. In FIG. 7F, the bonded three substrates are separated for each sensor.

Through these steps, the acceleration sensor shown in FIG. 4 is completed.

[0015]

A glass material is usually used for the second substrate 2 described above. The cutting resistance of the glass material is relatively large, but in the conventional manufacturing method, when the weight body 22 and the support body 21 are cut out from the glass material (see FIG.
(D) step), no consideration was given.

That is, in the conventional manufacturing method, the load and vibration are transmitted to the thin portion 13 when the glass material is cut. In particular, at the end of cutting, the weight of the weight body 22 was suddenly applied to the thin portion 13, and the impact was applied to the thin portion 13. The thin portion 13 is designed to detect weak acceleration.
It is particularly thin and requires careful handling.

In consideration of such problems, an object of the present invention is to provide a method for manufacturing a mechanical quantity sensor in which a load is not applied to a flexible portion.

[0018]

According to a first aspect of the present invention for achieving the above object, an action part and the action part are arranged so that the action part oscillates by a given mechanical amount. A flexible substrate supporting the flexible portion, a first substrate on which a fixed portion supporting the flexible portion is formed, a support body joined to the fixed portion, and a weight body joined to the acting portion. Second formed
A method for manufacturing a mechanical quantity sensor, which manufactures a mechanical quantity sensor using at least a substrate, wherein an auxiliary substrate is bonded to the second substrate, and the support and the weight are formed from the second substrate to which the auxiliary substrate is bonded. The body is cut out, and the first substrate and the second substrate are joined together in such a positional relationship that the fixing portion and the support body are joined together, and the acting portion and the weight body are joined together. A method of manufacturing a mechanical sensor is provided, wherein the auxiliary substrate is removed from the second substrate.

According to a second aspect of the present invention for achieving the above object, there is provided a method for manufacturing a mechanical quantity sensor according to the first aspect, wherein the auxiliary substrate is removed from the second substrate by etching. Provided.

According to a third aspect of the present invention for achieving the above object, in the second aspect, when the auxiliary substrate is removed from the second substrate, the first substrate is provided with the acting portion. There is provided a method for manufacturing a mechanical quantity sensor, characterized in that the flexible portion and the fixed portion are formed by the etching.

According to a fourth aspect of the present invention for achieving the above object, in the first, second or third aspect,
Provided is a method for manufacturing a mechanical quantity sensor, which comprises bonding a third board, which is a base of the mechanical quantity sensor, to a second board from which the auxiliary board has been removed.

According to a fifth aspect of the present invention for achieving the above object, in the first, second, third or fourth aspect,
A method of manufacturing a mechanical quantity sensor is provided, wherein the second substrate is a glass material.

According to a sixth aspect of the present invention for achieving the above object, in the first, second, third, fourth or fifth aspect, the mechanical quantity is acceleration. A method of manufacturing a quantity sensor is provided

[0024]

According to the present invention, the support body and the weight body are cut out from the second substrate to which the auxiliary substrate is joined, and then the first substrate and the second substrate are joined together. Mechanical load or vibration applied when cutting out the weight body is not transmitted to the flexible portion of the first substrate.

If etching is used for both the removal of the auxiliary substrate and the formation of the acting portion, the flexible portion, and the fixing portion, these can be carried out as a series of steps.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to manufacturing an acceleration sensor will be described below with reference to the drawings. Regarding the configuration of the target acceleration sensor,
Since it has already been described with reference to FIGS. 4 to 6, it is omitted here.

In manufacturing the acceleration sensor,
First, a silicon substrate is prepared, and an epitaxial layer of silicon is grown on the upper surface (hereinafter, the upper surface is the first surface and the lower surface is the second surface). Next, for example, a silicon nitride film is formed on both sides of the silicon substrate. The silicon nitride film on the second surface is
It is used in the etching process (process of FIG. 1B). An LP-CVD method (a low pressure chemical vapor deposition method) can be used for forming the silicon nitride film.

After that, the silicon nitride film on the epitaxial layer is peeled off to expose the epitaxial layer. For example, a silicon oxide film is grown on the exposed epitaxial layer. Then, this silicon oxide film is patterned by using photolithography, and a predetermined impurity is diffused into the epitaxial layer through the patterned silicon oxide film to form each resistance element (specifically, piezoresistor). Wiring of required metal wires is also performed at the same time. If the number and arrangement of the resistance elements are changed,
It becomes possible to detect the accelerations about the three axes arbitrarily.

On the other hand, a pattern of an etching mask is formed by photolithography on the silicon nitride film left on the second surface of the silicon substrate.

The silicon substrate which has undergone the above steps is shown in FIG.
This is shown in FIG. Since these steps are already well known, the description using the drawings is omitted, but the present embodiment is not limited to these steps. In addition,
The silicon substrate is hereinafter referred to as the first substrate 1. Further, in FIG. 1A, 11 is a resistance element and 12 is an etching mask. The boundary indicating the unit of the acceleration sensor is
It is indicated by a broken line in FIGS. 1 (a) to 1 (e).
The crystal plane of the first substrate (silicon substrate) 1 is (100)
(A plane parallel to the plane A shown in FIG. 1A).

Next, etching is performed from the second surface of the first substrate 1 with a strong alkaline aqueous solution (eg, potassium hydroxide aqueous solution) to advance the etching to the back side of the epitaxial layer in which the resistance element 11 is embedded. Figure 1 (b)
Shows that the etching is completed.
The substrate 1 is provided with an action portion (here, a thick portion in the center) 14, a fixed portion (here, a thick portion in the periphery) 15, and a flexible portion (here, a thin portion 13).

Subsequently, a glass substrate (hereinafter referred to as the second substrate 2) having a shape as shown in FIG. 8 is bonded to a silicon substrate (hereinafter referred to as the auxiliary substrate 4) as shown in FIG. For this bonding, for example, an anodic bonding method is used. The anodic bonding method is a method in which a predetermined voltage is applied between the members to be bonded to raise the temperature, and the members are bonded while being pressed. After joining the auxiliary substrate 4 to the second substrate 2, the second substrate 2 is cut along the guide grooves with a dicing blade. This disconnection
The weight body 22 and the support body 21 are completely separated on the auxiliary substrate 4. In addition, the support 21 becomes independent for each sensor by this dicing operation.

Regarding the second substrate 2, the support 21
The first surface of the weight body 22 (the central thick portion 14
(Excluding the joint portion with) is previously subjected to an etching treatment so as to be slightly lower. Further, the peripheral thick portion 15 is formed so as to slightly project from the support body 21 toward the center side when the first substrate 1 and the second substrate 2 are bonded together. Therefore, the upward movement of the weight body 22 is limited by the peripheral thick portion 15. By limiting the movement of the weight body 22 in this manner, the thin portion 13 is not excessively deformed, so that the thin portion 13 can be prevented from being broken. Since the member strengths of the first substrate 1 and the second substrate 2 are relatively large, the peripheral thick portion 1 of the first substrate 1
Even if the weight 5 and the weight body 22 of the second substrate 2 come into contact with each other, they are not damaged. The second substrate 2 is also preliminarily formed with the guide groove used in the above dicing work.

Next, the second substrate 2 to which the auxiliary substrate 4 is joined is joined to the first substrate 1. In the joining, the first surface of the support body 21 and the second surface of the peripheral thick portion 15 and the first surface of the weight body 22 and the second surface of the central thick portion 14 are joined together, respectively. Execute after positioning. The state where the second substrate 2 is bonded to the first substrate 1 is shown in FIG.

Subsequently, the auxiliary substrate 4 is removed from the second substrate 2. The removal is performed by etching with a strong alkaline aqueous solution (for example, potassium hydroxide aqueous solution). Even if the auxiliary substrate 4 is removed, since the weight body 22 and the support body 21 are already bonded to the first substrate 1, they do not scatter. The state where the removal process is completed is shown in Fig. 1.
This is shown in (d).

After that, as shown in FIG. 1E, a silicon substrate (hereinafter, referred to as a third substrate 3) is bonded to the second substrate 2.

After the first substrate 1, the second substrate 2, and the third substrate 3 are integrated in this way, they are separated for each acceleration sensor. The separation is performed, for example, by cutting the first substrate 1 and the third substrate 3 with a dicing blade,
Each of the first substrate 1 and the third substrate 3 is a silicon substrate and has a relatively small cutting resistance, and since it is not necessary to cut the second substrate 2 which is a glass material, an excessive load is not applied to each substrate. .

The third substrate 3 has its first surface etched in advance so that a space is formed below the weight body 22, and the weight body 22 is not moved downward. , Limited by the first surface of the third substrate 3.

Next, another embodiment of the present invention will be described with reference to FIG.

In the present embodiment, the etching for removing the auxiliary substrate 4 from the second substrate 2 and the etching for forming the central thick portion 14, the peripheral thick portion 15 and the thin portion 13 are continuously performed. are doing.

That is, after carrying out the step of FIG. 2A which is the same step as FIG. 1A, the auxiliary substrate 4 is connected to the second substrate 2, and the second substrate 2 on the auxiliary substrate 4 is Similarly to the above, the weight body 22 and the support body 21 are cut out. After this, FIG.
As shown in (b), the second substrate 2 is bonded to the first substrate. At this time, the weight body 22 is overlapped with the etching mask for leaving the central pressed portion 14 at the time of etching.
Further, the support 21 is aligned so as to overlap with the etching mask for leaving the peripheral pressure-reduced portion 15 at the time of etching, and these are joined.

Then, as shown in FIG. 2C, the auxiliary substrate 4 is removed by etching with a strong alkaline aqueous solution (eg, potassium hydroxide aqueous solution), and subsequently, as shown in FIG. 13, the central pressed portion 14 and the peripheral pressed portion 15 are respectively formed. As described above, in the present embodiment, the removal of the auxiliary substrate 4, the thin portion 13, the central pressed portion 14
Further, since the peripheral pressed portion 15 is formed by a series of etching processes, the manufacturing process can be further simplified.

Then, in FIG. 2 (e), the third substrate 3 is changed to the second substrate.
It is bonded to the substrate 2 and separated for each acceleration sensor in FIG. Regarding these steps, FIG.
Since it is the same as the step (f), detailed description thereof will be omitted.

Although the embodiment of the present invention has been described above, the present invention can be applied to a mechanical quantity sensor other than the acceleration sensor.

[0045]

According to the present invention, the support body and the weight body can be cut out from the second substrate without applying any load to the flexible portion.

[0046]

[Brief description of drawings]

FIG. 1 is an explanatory diagram related to each step of an embodiment when the present invention is applied to manufacturing an acceleration sensor.

FIG. 2 is an explanatory diagram regarding each step of another embodiment when the present invention is applied to manufacture of an acceleration sensor.

FIG. 3 is a second view used in the embodiment shown in FIGS. 1 and 2;
The block diagram of a board | substrate and an auxiliary board.

FIG. 4 is a sectional view of a conventional acceleration sensor.

FIG. 5 is an explanatory view (No. 1) of the operation of the conventional acceleration sensor.

FIG. 6 is an explanatory view (part 2) of the operation of the conventional acceleration sensor.

FIG. 7 is an explanatory diagram relating to a method of manufacturing a conventional acceleration sensor.

FIG. 8 is a configuration diagram of a second substrate of a conventional acceleration sensor.

[Explanation of symbols]

 1: 1st substrate, 2: 2nd substrate, 3: 3rd substrate, 4: 4th substrate, 11: resistance element, 12: etching mask, 13: thin part, 14: central thick part, 15: peripheral thickness Meat part, 21: support body, 22: weight body

Claims (6)

[Claims] 1. A working part, a flexible part that supports the working part so that the working part oscillates by a given mechanical amount, and a fixing part that supports the flexible part. Method for manufacturing a mechanical quantity sensor using at least a first substrate, a support body joined to the fixed portion, and a second substrate on which a weight body joined to the action portion is formed In, joining an auxiliary substrate to the second substrate, cutting out the support body and the weight body from the second substrate to which the auxiliary substrate is joined, the fixing portion and the support body are joined, and A mechanical quantity characterized by joining the first substrate and the second substrate in a positional relationship such that the acting portion and the weight body are joined, and removing the auxiliary substrate from the second substrate. Sensor manufacturing method. 2. The method for manufacturing a mechanical sensor according to claim 1, wherein the auxiliary substrate is removed from the second substrate by etching. 3. The method according to claim 2, wherein when the auxiliary substrate is removed from the second substrate, the acting portion, the flexible portion, and the fixing portion are formed on the first substrate by the etching. A method for manufacturing a mechanical quantity sensor characterized by the above. 4. The method for manufacturing a mechanical quantity sensor according to claim 1, 2 or 3, wherein a third substrate which is a base of the mechanical quantity sensor is joined to the second substrate from which the auxiliary substrate is removed. 5. The method for manufacturing a mechanical quantity sensor according to claim 1, 2, 3 or 4, wherein the second substrate is a glass material. 6. The method for manufacturing a mechanical quantity sensor according to claim 1, 2, 3, 4 or 5, wherein the mechanical quantity is acceleration.