JPH06324077A - Semiconductor acceleration sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a semiconductor acceleration sensor, wherein a movable electrode (overlapped part) can be arranged in a sealed space with the relatively simple constitution, and the manufacturing method thereof. CONSTITUTION:Aluminum is applied on the entire upper surface of a glass plate 10 by vapor deposition, and a fixed electrode 11 is formed. A thin glass layer 12 is provided on the upper surface of the fixed electrode 11 by sputtering. One side of the glass layer 12 is cut in the slender strip shape. The fixed electrode 11 is exposed at the cup-out part. A lead wire 14 is connected. A silicon plate 15 is arranged on the upper surface of the glass layer 12. The lower surface of an approximately square-shaped frame body 16 and the glass layer 12 are brought into contact as the screen, and the airtightness is maintained. A glass plate 20 is arranged at the upper part of the silicon plate 15. The surface contact is provided with the upper surface of the frame body and bonding is performed. An overlapped part 18 of the silicon plate 15 and a movable electrode 19 are positioned in a sealing space, which is automatically formed by the manufacture of a sensor.

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 and a method of manufacturing the same, and more particularly to improvement of a mounting structure of electrode leads.

[0002]

2. Description of the Related Art In a capacitance type semiconductor acceleration sensor used for vehicle body control or engine control of an automobile, glass plates 2 are arranged on both upper and lower sides of a silicon plate 1 which generally constitutes a movable electrode, as shown in FIG. To do. At this time, a predetermined gap is formed between the movable electrode and the facing surface of the glass plate 2,
The movable electrode is allowed to swing. And this glass plate 2
The fixed electrode is formed by aluminum vapor deposition or the like on a predetermined position of the inner surface of, i.e., the surface facing the movable electrode. When the movable electrode swings as described above, the gap between the movable electrode and the fixed electrode changes, and the electrostatic capacitance generated between both electrodes changes.

In order to detect such a change in capacitance, it is necessary to lead out the wiring (electrode lead) connected to both electrodes to the outside. However, such a lead-out should be continuous on the fixed electrode side, for example. To form the aluminum wiring 3 on the upper surface of the glass plate 2. Then, a predetermined portion of the silicon plate 1 is cut off to expose the end portion 3a of the aluminum wiring 3 to be a pad for taking out, and a portion corresponding to the aluminum wiring 3 on the lower surface side of the silicon plate 1 is a concave groove 1a. Is formed, and the lower surface of the glass plate 2 other than the concave groove 1a is joined to the lower glass plate 2.

[0004]

However, in the above-mentioned conventional configuration, it is difficult to match the shape of the concave groove 1a formed in the silicon plate 1 with the outer shape of the aluminum wiring, and therefore the concave groove 1a is formed. The width and the depth are set to be larger than the width and the height of the aluminum wiring 3 by one or more, respectively, and a gap is created between the two as shown in the figure. Therefore, there is a possibility that dust or the like may enter the inside through the gap, causing a failure. Therefore, it is necessary to fill the gap with resin or the like and seal the gap after manufacturing, which makes the work complicated.

Further, since the pressure of air changes depending on the temperature, it is preferable to depressurize and seal the inside of the sensor. However, in the above sensor, the inside of the sensor is in communication with the outside through the gap formed between the aluminum wiring 3 and the groove 1a of the silicon plate 1, and even if the inside of the sensor is sealed after manufacturing as described above, The pressure cannot be reduced, and air is present in the sensor, which reduces the accuracy of the sensor under the influence of the air.

The present invention has been made in view of the above background, and an object thereof is to bring a bonding surface of a semiconductor substrate such as silicon having a movable electrode and another plate material connected thereto into surface contact. A semiconductor acceleration sensor and a method of manufacturing the same, in which a movable electrode (a swinging weight portion) can be arranged in a hermetically sealed space with a relatively simple structure and the pressure in the sealed space can be reduced. To provide.

[0007]

In order to achieve the above object, in a semiconductor acceleration sensor according to the present invention, a metallic fixed electrode is provided on a substrate, and the fixed electrode and, if necessary, the substrate is exposed. The bonding glass layer was provided so as to cover the portion, and the semiconductor substrate having the movable electrode facing the fixed electrode was bonded to the bonding glass layer, and the bonding portion was endless.

Further, a metallic fixed electrode having a predetermined shape and a metallic wiring for the movable electrode are provided on the substrate so as to be separated from the fixed electrode, and the fixed electrode, the wiring and the exposed portion of the substrate are provided. Provide a glass layer for bonding so as to cover,
A semiconductor substrate having a movable electrode facing the fixed electrode is bonded to the bonding glass layer, and
The joining portion is endless, and a window hole is formed at a predetermined position inside the joining portion of the joining glass layer so that a part of the wiring can be exposed, and is formed on the semiconductor substrate through the window hole. The end face of the pad that is electrically connected to the movable electrode may be brought into contact with a part of the wiring.

In the method of manufacturing the sensor having the above structure, a metal such as aluminum is vapor-deposited on a substrate to form the fixed electrode, and then the fixed electrode is glass-coated to cover the fixed electrode. The region is removed to form a bonding glass layer, and then a semiconductor substrate having a movable electrode of a predetermined shape formed in another step is bonded onto the bonding glass layer.

Further, a metal such as aluminum is vapor-deposited on the substrate,
A predetermined portion of the vapor-deposited metal is cut off to form wirings for the fixed electrode and the movable electrode, and then glass coating is performed so as to cover the fixed electrode and the wiring, and a predetermined portion of the glass coating on the wiring is formed. The bonding glass layer is formed by removing the part to form the bonding glass layer with the window, and then having a movable electrode having a predetermined shape formed in a separate step and having the pad at a predetermined position. You may make it join on a layer.

[0011]

[Function] The silicon plate is bonded only to the bonding glass layer,
Moreover, since the joint portion is endless, it is completely sealed. Since the sensor is automatically sealed by manufacturing, no special sealing process is required after manufacturing. Further, if the manufacturing is performed in, for example, a depressurized atmosphere, the inside of the sensor can be in a depressurized state, and the movable electrode located inside the joint is located in the depressurized inside. Highly accurate detection can be achieved with minimal suppression.

[0012]

Preferred embodiments of a semiconductor acceleration sensor and a method of manufacturing the same according to the present invention will be described below in detail with reference to the accompanying drawings. 1 and 2 show a first embodiment of the present invention. As shown in the figure, a rectangular glass plate 10 serving as a substrate
The fixed electrode 11 is formed on the upper surface of the. This fixed electrode 1
In this example, 1 is formed by vapor deposition of aluminum so as to have substantially the same planar shape as the glass plate 10, that is, to cover the entire upper surface of the glass plate 10.

A thin glass layer 12 is formed so as to cover the upper surface of the fixed electrode 11. This glass layer 12 is
As shown in FIG. 2, one side of the fixed electrode 11 has a rectangular shape that is cut into an elongated strip shape with respect to the planar shape of the fixed electrode 11, and covers almost the entire surface of the fixed electrode 11. Then, a pad 13 is formed on the surface of the fixed electrode 11 which is exposed without forming the glass layer 12, and the lead wire 14 is connected to the pad 13.

Further, a silicon plate 15 is arranged on the upper surface of the glass layer 12. The silicon plate 15 has a shape in which a weight portion 18 is swingably formed on the inner surface of a substantially rectangular frame 16 via a beam portion 17, and the lower surface of the weight portion 18 serves as a movable electrode 19. Then, the outer shape of the frame body 16 and the outer shape of the glass layer 12 are substantially matched. As a result, the lower surface of the frame body 16 comes into contact only with the glass layer 12, and the joint surfaces thereof are flush with each other, so that the airtightness at the surface-contacted joint portion is improved. Since this joint portion is formed over the entire surface of the frame body 16, it is endlessly positioned over the entire circumference, and the joint surface between the silicon plate 15 and the glass layer 12 is completely sealed. An electrostatic capacitance is generated between the movable electrode 19 and the fixed electrode 11.

Furthermore, since the glass plate 20 is disposed above the silicon plate 15 and the joint surface between the silicon plate 15 and the glass plate 20 is also in surface contact over the entire circumference, the joint surface is airtight. . As a result, the weight portion 18,
The movable electrode 19 is located in the sealed space, and since this sealing structure is automatically performed by manufacturing the sensor,
It is also possible to reduce the pressure in the sealed space, and in such a case, it is possible to suppress the influence on the temperature. Like the glass layer 12, the glass plate 20 has a rectangular shape (provided that the inside of the frame body 16 is cut off in a strip shape on one side of the planar shape of the silicon plate 15 located therebelow. It is larger than the shape) and covers almost the entire surface of the silicon plate 15. Then, a pad 21 is formed at a predetermined position on the surface of the frame body 16 of the silicon plate 15 which is exposed without forming the glass plate 20, and the lead wire 22 is connected to the pad 21.

That is, in this example, glass plates are arranged on the upper and lower sides of a silicon plate having a movable electrode, which is a conventional general semiconductor acceleration sensor, and at least one of the glass plates has a silicon plate. The fixed electrode and its wiring were formed by aluminum vapor deposition on the plate facing surface at a predetermined position (with the glass plate (which is anodically bonded) and the aluminum vapor deposition wiring being located on the bonding surface with the silicon plate) as a reference, The glass layer 12 for joining is arranged between the aluminum vapor deposition forming the fixed electrode and the wiring and the silicon plate, and only the glass layer is positioned on the joining surface with the silicon plate to improve the airtightness. There is.

In this example, aluminum is used as the glass plate 10.
Since the fixed electrode 11 was formed by vapor deposition on the entire upper surface of the above, strictly speaking, a part of the fixed electrode 11 is
It also serves as the conventional wiring.

Further, although aluminum is vapor-deposited on the entire surface in this example, it may be patterned like a fixed electrode and a wiring having a conventional predetermined pattern. In that case, the glass layer covers both the upper surface of the aluminum vapor deposition (fixed electrode) having a predetermined pattern and the exposed surface of the glass plate, and in any case, the bonding with the silicon plate takes place. It comes to be done through a glass layer.

Further, in this embodiment, the fixed electrode 11 is formed on the lower side, but, although not specifically shown, on the contrary, on the lower surface of the upper glass plate 20, the whole surface or a predetermined pattern as described above. It is, of course, possible to form a fixed electrode made of and to arrange the glass layer so as to cover the fixed electrode.

Furthermore, as shown in FIG. 3, fixed electrodes 11 and 24 may be formed on both surfaces of the upper and lower glass plates 10 and 20, respectively. That is, the glass layer 25 is formed so as to further cover the lower surface of the fixed electrode 24 formed by aluminum vapor deposition on the lower surface of the glass plate 20. And the weight part 1
The upper surface of 8 is the movable electrode 26, and electrostatic capacitance is exerted between the movable electrode 26 and the fixed electrode 24. Further, a lead wire 28 is formed on the exposed surface of the fixed electrode 24 via the pad 27, and the silicon plate 1
5, a pad 29 connected to the movable electrode 26 and a lead wire 30 are formed at predetermined positions. The lower glass plate 10 side is the same as in the first embodiment described above, so the same reference numerals are given and its description is omitted.

Next, the manufacturing method of the above embodiment will be described with reference to FIG. First, a glass plate 10 serving as a substrate is prepared, aluminum is vapor-deposited on its upper surface to manufacture a fixed electrode 11, and a glass layer is formed on the upper surface by glass coating (or sputtering, vapor deposition, etc.) (-).
Then, glass etching is performed to cut out a predetermined position of the formed glass layer to form the glass layer 12 ().

Then, the silicon plate 15 having a predetermined shape manufactured in a separate step is placed on the glass layer 12 and is anodically bonded to be integrated (). Then, the glass plate 20 provided with the aluminum vapor deposition (fixed electrode 24) glass-coated with the glass layer 25 manufactured by the steps similar to the above is prepared, and the glass layer 25 side faces down on the silicon plate 15. Place it on and anodic-bond it to integrate (). Then, wire bonding is performed at a predetermined position on the exposed surface to form lead wires and the like, and the manufacturing is finished ().

Although this example is a manufacturing process for a structure in which fixed electrodes are arranged on both sides shown in FIG. 3, if only the glass plate 20 is bonded to the upper surface of the silicon plate 15 in the above process, This is a process for manufacturing the semiconductor acceleration sensor of the first embodiment shown in FIG.

5 and 6 show a second embodiment of the present invention. In this example, unlike the first embodiment described above, the movable electrode lead-out 24 is taken out from the fixed electrode side, that is, the glass plate side. That is, the lower glass plate 1
A fixed electrode 11 'having a predetermined shape is formed on the upper surface of 0 by aluminum vapor deposition. Further, a wiring 31 for a movable electrode is formed by aluminum vapor deposition at a predetermined position on the upper surface of the glass plate 10 at a position separated from the fixed electrode 11 '.

On the other hand, as in the first embodiment, the fixed electrode 1
1'and the glass layer 1 so as to cover the wiring 31
2'is formed by sputtering or the like. Further, one side of the glass layer 12 'is also cut out in a strip shape to expose a part of the glass plate 10. Then, at the exposed portion, the end portion 11'a of the fixed electrode 11 'and one end 31 of the wiring 31 are formed.
a is arranged and used as a pad for taking out.

Further, in this example, a window hole 12'a penetrating vertically is formed at a predetermined position of the glass layer 12 ', that is, at a position facing the other end 31b of the wiring 31, and the other end 31b of the wiring 31 is formed. I'm trying to expose it.

A silicon plate 15 'provided with a movable electrode 19 is arranged above the glass layer 12', and the silicon plate 15 'is movable on a lower surface of the silicon plate 15' so as to face the window hole 12'a. An aluminum pad 32 that is electrically connected to the electrode 19 is provided, and when the silicon plate 15 ′ is mounted on the glass layer 12 ′, the lower end of the aluminum pad 32 is the window hole 1
It passes through the inside of 2'a and is crimped to the other end 31b of the wiring 31. As a result, the movable electrode 19 and the wiring 30 are brought into conduction, and can be taken out to the outside through the one end 31a of the wiring 31.
The rest of the configuration and operation are the same as those of the first embodiment described above, so description thereof will be omitted.

Also in the type of the second embodiment, the movable electrodes 19 'are formed on both sides of the weight portion 17' of the silicon plate 15 ', as in the modification of the first embodiment (shown in FIG. 3). , 26 'and fixed electrodes 11', 24 'may be provided at predetermined positions on the facing surfaces of both glass plates 10, 12. That is, the fixed electrode 24 'formed on the lower surface of the upper glass plate 12 at a predetermined position is not formed on the entire lower surface of the glass plate 12 but has a predetermined shape, and the wiring 33 for the movable electrode is formed on the non-arranged portion. The movable electrode 26 'formed on the upper surface of the silicon plate 15' at a predetermined position on the upper surface thereof.
A window hole 25'a formed by forming an aluminum pad 35 that conducts to
The inside is inserted and arranged, and the upper end thereof is crimped to the other end 33b of the wiring 33. The rest of the configuration and operation are the same as those of the above-described embodiments and modifications, and the description thereof will be omitted.

FIG. 7 shows a manufacturing process of the acceleration sensor of the second embodiment. As shown in the figure, after aluminum is vapor-deposited on the entire upper surface of the glass plate 10, patterning is performed at predetermined positions to remove a part of the vapor-deposited aluminum.
As a result, the fixed electrode and the wiring as shown in FIG. 5 are formed ('-').

Then, the aluminum vapor deposition parts (11 ',
31) and glass coating on the exposed upper surface of the glass plate 10 to make the surface flush. Then, a predetermined portion of the glass layer coated with glass (the strip-shaped portion on one side and the window hole 12'a) is removed by glass etching (','). Then, an aluminum pad is formed at a predetermined position manufactured in another step. Three
A silicon plate 15 'having a predetermined shape provided with 2, 35 is placed on the glass layer 12' and anodically bonded to integrate ('). Then, a glass plate 2 having an aluminum vapor deposition (fixed electrode, wiring) glass-coated with a glass layer 25 'manufactured by the same steps as the above-mentioned steps
0 is prepared, and the silicon plate 1 is placed with the glass layer 25 'side facing down.
It is placed on 5'and anodically bonded to integrate ('). Then, wire bonding is performed at a predetermined position on the exposed surface to form lead wires and the like, and the manufacturing is completed (').

Although this example is a manufacturing process for a structure in which fixed electrodes are arranged on both sides shown in FIG. 3, only the glass plate 20 is bonded to the upper surface of the silicon plate 15 in the above process. By using the silicon plate 15 'with the aluminum pad only on the lower surface side,
This is a process for manufacturing the semiconductor acceleration sensor of the first embodiment shown in FIG.

The present invention is not limited to the above-described embodiment. For example, in the case of a type in which fixed and movable electrodes are provided on both sides, one uses the structure of the first embodiment and the other uses the structure of the second embodiment. You may make it use a structure. Furthermore, although the fixed electrodes and wirings are formed by aluminum vapor deposition in each of the above-described embodiments, other metals may of course be used.

[0033]

As described above, in the semiconductor acceleration sensor and the method of manufacturing the same according to the present invention, the fixed electrode (and the wiring) is not located on the bonding surface of the semiconductor substrate such as silicon but covers the surface thereof. Since the bonded glass layer thus formed and the semiconductor substrate are bonded to each other, the bonded portion is in surface contact with the airtightness. Further, since the airtightness is automatically performed by manufacturing the sensor, no special sealing process is required, and the manufacturing can be easily performed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of a semiconductor acceleration sensor according to the present invention.

FIG. 2 is a perspective view showing a main part thereof.

FIG. 3 is a sectional view showing a modification thereof.

FIG. 4 is a diagram showing a manufacturing process of the acceleration sensor.

FIG. 5 is a sectional view showing a second embodiment of the semiconductor acceleration sensor according to the present invention.

FIG. 6 is a perspective view showing a main part thereof.

FIG. 7 is a sectional view showing a modification thereof.

FIG. 8 is a diagram showing a manufacturing process of the acceleration sensor.

FIG. 9 is a diagram showing an example of a conventional semiconductor acceleration sensor.

[Explanation of symbols]

 10 Glass Plate (Substrate) 11, 11 'Fixed Electrode 12, 12' Glass Layer (Glass Layer for Bonding) 15, 15 'Silicon Plate (Semiconductor Substrate) 19 Movable Electrode

Claims (5)

[Claims] 1. A metal fixed electrode is provided on a substrate, a bonding glass layer is provided so as to cover the fixed electrode and, if necessary, an exposed portion of the substrate, and the bonding glass layer is provided with the bonding glass layer. A semiconductor acceleration sensor, characterized in that a semiconductor substrate having a movable electrode facing a fixed electrode is bonded, and the bonding portion is endless. 2. A fixed metal electrode having a predetermined shape and a metal wiring for a movable electrode are provided on the substrate so as to be separated from the fixed electrode, and the fixed electrode, the wiring and the exposed portion of the substrate are provided. A bonding glass layer is provided so as to cover, and a semiconductor substrate having a movable electrode facing the fixed electrode is bonded to the bonding glass layer, and the bonding site is endless, and A window hole that allows a part of the wiring to be exposed is provided at a predetermined position inside the bonding portion of the bonding glass layer, and the end surface of the pad that is electrically connected to the movable electrode formed on the semiconductor substrate through the window hole is described above. A semiconductor acceleration sensor characterized by being brought into contact with part of wiring. 3. A take-out pad is formed by cutting out a predetermined portion on the outer peripheral side of the joining portion of the joining glass layer to expose at least a part of the fixed electrode.
Alternatively, the semiconductor acceleration sensor described in 2. 4. A metal such as aluminum is vapor-deposited on a substrate to form the fixed electrode, and then glass coating is performed so as to cover the fixed electrode, and a predetermined portion of the coating is removed to form a bonding glass layer. A method of manufacturing a semiconductor acceleration sensor, comprising forming and then bonding a semiconductor substrate having a movable electrode having a predetermined shape, which is formed in a separate step, onto the bonding glass layer. 5. A metal such as aluminum is vapor-deposited on a substrate, predetermined portions of the vapor-deposited metal are cut off to form wirings for the fixed electrode and the movable electrode, and then the fixed electrode and wiring are covered. As described above, the glass coating is performed, and the predetermined portion of the glass coating on the wiring is removed to form the glass layer for bonding with the window hole, and then, the movable electrode having a predetermined shape is formed in another step. At the same time, a method of manufacturing a semiconductor acceleration sensor, wherein a semiconductor substrate having the pad at a predetermined position is bonded onto the bonding glass layer.