JP2000340804A - Manufacture of semiconductor acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method of manufacturing a semiconductor acceleration sensor by which a cantilever can be prevented from being broken and an assembling work can be done easily. SOLUTION: A bridge 28 made of an aluminum wire is formed between an aluminum thin film 7 and a pad 14' on the surface of a mass part 5 by an aluminum wire bonding across a slit 10. This aluminum wire bonding is carried out before allowing the slit 10 to penetrate to prevent the breaking of a cantilever 4. The bridge 28 is formed while its thickness is being adjusted, so as to be fused when a current flows. After separating into respective sensor chips 1 through dicing, a terminal connected with a power source such as a probe or the like abuts against a pad for applying voltage 16 of the sensor chip, then the current is passed through the bridge 28 so as to fuse the bridge 28 by applying the voltage between the both pads 16 for applying voltage, and the cantilever 4 is made operatable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor acceleration sensor.

[0002]

2. Description of the Related Art FIGS. 13 and 14 are diagrams showing the configuration of an example of a conventional semiconductor acceleration sensor. In the semiconductor acceleration sensor, a gauge resistor 6 is formed on a sensor chip 1, and a thin support (also referred to as a cantilever or beam, hereinafter referred to as a cantilever) 4 supporting a mass portion 5 which is a weight is provided on the back surface of the gauge resistor 6. Are formed.

When an acceleration α is applied in a direction perpendicular to the sensor chip 1, a force F = mα is generated in the mass portion 5.

[0004] The force F causes the cantilever 4 to bend, causing distortion on the surface. The distortion changes the value of the gauge resistor 6. Four gauge resistors 6 are arranged on the cantilever 4, and these are connected in a bridge to obtain a voltage signal proportional to the acceleration, thereby detecting the acceleration.

A semiconductor acceleration sensor having such a structure is generally called a cantilever type semiconductor acceleration sensor.

A conventional semiconductor acceleration sensor is manufactured as follows. First, a silicon single crystal wafer having a (100) crystal plane is oxidized to form an oxide film 8, and then the oxide film 8 in a region where the cantilever 4 and the mass portion 5 are to be formed in the future.
Is removed by photolithography in a shape close to a U-shape. Next, silicon is etched using the oxide film 8 as an etching mask. The etching depth is generally about 6 μm to 30 μm. Then, oxidation is performed again, and a P + diffusion layer is formed to make contact with aluminum. Subsequently, two diffusion gauge resistors (hereinafter referred to as “gauge resistors”) 6 are formed on the two cantilevers 4 by ion implantation so as to form a bridge with each other.

Finally, an aluminum wiring 13 is connected to a P + diffusion wiring 11 connected to the gauge resistor 6 at a contact portion 12, and this aluminum wiring 13 is formed around the sensor chip 1 for wire bonding. Pad 1
4, and a power supply wiring of an external terminal and an output wiring are connected to the pad 14 by wire bonding. 1
Reference numeral 5 denotes a wiring wire.

Further, as a protective film for the aluminum wiring 13,
Passivation with nitride film. Subsequently, an aluminum thin film 7 to be joined to the upper glass stopper 2 is formed, and the aluminum thin film 7 is passivated with a nitride film. Then, the cantilever 4 is made thinner from the back surface of the sensor chip 1 by alkali anisotropic etching and penetrated around the mass portion 5 to form a slit 10 having a substantially U-shape.

After that, the aluminum thin film 1 to be bonded to the aluminum wiring 13, the bonding pad 14, and the glass stopper 2
3 is removed. In the figure, reference numeral 9 denotes a remaining nitride film.

The glass stoppers 2 and 3 are joined to the upper and lower sides of the cantilever 4 thus formed and the mass 5 serving as a weight by anodic bonding to form an air damping structure. The space in the upper and lower glass stoppers 2 and 3 is called a cavity.

[0011]

In the method of manufacturing a silicon semiconductor acceleration sensor as described above, the cantilever 4 is used.
Once formed, it is very difficult to handle, cleaning with chemicals or pure water, wafer transfer, glass stopper bonding,
In the process of dicing a wafer, die bonding to a substrate, wire bonding, and the like, vibration is often applied to the cantilever 4 and the cantilever 4 is often damaged. And the yield was quite low. Therefore, the cost is extremely high, and it has not been possible to manufacture an inexpensive and highly sensitive small-sized semiconductor acceleration sensor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a semiconductor acceleration sensor which can be easily assembled without causing breakage of the cantilever during the manufacturing process. It is to provide a manufacturing method.

[0013]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the object,
According to the first aspect of the present invention, the mass portion, the sensor chip provided so as to surround the mass portion via the slit, and the sensor chip and the mass portion are connected by an elastic beam to form the mass portion. In a method for manufacturing a semiconductor acceleration sensor in which a supporting body to be supported, a gauge resistor formed on the supporting body, and a glass stopper on each side of the sensor chip, at least one outer periphery of the mass portion, To
The sensor chip is fixed with a bridge of a low-resistance metal wire formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for flowing a current through the low-resistance metal wire is provided on the sensor chip. After joining the stopper, the individual sensor chips are diced, and after the dicing, current is supplied to the low-resistance metal wire by applying the current to both ends of the low-resistance metal wire to blow the low-resistance metal wire. And the support is made movable.

According to a second aspect of the present invention, in the first aspect of the present invention, the low-resistance metal wire is an aluminum wire.

According to a third aspect of the present invention, in the first aspect, the low-resistance metal wire is a gold wire.

According to the fourth aspect of the present invention, the mass portion, the sensor chip provided so as to surround the mass portion via the slit, and the sensor chip and the mass portion are connected by an elastic beam. In a method of manufacturing a semiconductor acceleration sensor in which a support supporting the mass portion, a gauge resistor formed on the support, and a glass stopper on each side of the sensor chip, at least one outer periphery of the mass portion, The sensor chip is fixed with a thin-film bridge of a low-resistance metal thin film formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for flowing a current through the thin-film bridge is provided in the sensor chip. After bonding glass stoppers to both sides of the chip, individual sensor chips are diced, and after the dicing, voltage is applied to both ends of the thin film bridge via current paths. The blown a thin film bridge by applying a current to the thin film bridge, characterized in that the support and movable.

According to a fifth aspect of the present invention, in the fourth aspect, the thin film bridge is made of an aluminum thin film.

According to a sixth aspect of the present invention, in the fourth aspect, the thin film bridge is made of a gold thin film.

According to a seventh aspect of the present invention, in the fourth aspect, the thin-film bridge is formed by a two-layer structure of a gold thin film and an aluminum thin film.
It is characterized by applying heat of 0 ° C. or more.

According to the invention of claim 8, the mass portion, the sensor chip provided so as to surround the mass portion through the slit, and the sensor chip and the mass portion are connected by an elastic beam. In a method of manufacturing a semiconductor acceleration sensor in which a support supporting the mass portion, a gauge resistor formed on the support, and a glass stopper on each side of the sensor chip, at least one outer periphery of the mass portion, The sensor chip is fixed with a bridge made of a polysilicon resistive thin film formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for flowing current through the bridge is provided in the sensor chip. After the glass stoppers are bonded to both sides of the bridge, the individual sensor chips are diced. The blown the bridge by applying a current to the bridge, characterized in that the support and movable.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

(Embodiment 1) FIG. 1 is a plan view of a chip sensor 1 of the present embodiment before a glass stopper is joined.

In manufacturing the semiconductor acceleration sensor of this embodiment, a silicon single crystal wafer having a (100) crystal plane is first oxidized to form an oxide film in the same manner as in the above-mentioned conventional example, and then a cantilever 4 is formed. Then, only the oxide film in the region where the mass portion 5 is to be formed is removed by a photolithography technique in a shape close to a U-shape. Next, silicon is etched using the oxide film as an etching mask. The etching depth is generally about 6 μm to 30 μm. Then, oxidation is performed again, and a P + diffusion layer is formed to make contact with the aluminum wiring. Subsequently, two gauge resistors 6 each composed of a diffusion gauge resistor are formed on the two cantilevers 4 by ion implantation so as to form a bridge with each other.

Next, aluminum sputtering and sintering (about 450 ° C.) are performed to form an aluminum wiring 13, a wire bonding pad 14, and a voltage application pad 1.
6, 16 and a pad 14 'for wire bonding are formed on the upper surface of the mass section 5.

At this time, an aluminum wiring 13 is connected to the P + diffusion wiring 11 connected to the gauge resistor 6 by a contact portion 12, and the aluminum wiring 13 is formed on the periphery of the sensor chip 1 of the semiconductor acceleration sensor by wire bonding. Connected to the pad 14.

Further, an aluminum thin film 7 to be joined to an upper glass stopper (not shown) is simultaneously formed on the oxide film and the nitride film which are the insulating protective films on the P + diffusion wiring 11.

The aluminum thin film 7 and the pad 14 'on the upper surface of the mass portion 5 are bonded by aluminum wire bonding to form a bridge 28 made of aluminum wire.
Is formed at a position corresponding to the part. The aluminum wire bonding is performed before the slit 10 is formed to prevent the cantilever 4 from being broken.

The bridge 28 is formed by adjusting the thickness so as to be blown when an electric current is applied. Here, the fusing current of the aluminum wire is, for example, about 0.
3A. This aluminum wire bridge 28
One or more slits 10 may be provided.

One end of the aluminum wire bridge 28 is connected to the voltage applying pad 16 through the aluminum thin film 7 joined to the upper glass stopper (not shown), and the other end is connected to the aluminum wiring 13 by the aluminum wiring 13. P + which is connected to the contact portion 12 on the upper surface of the substrate 5 and further passes from the contact portion 12 on the cantilever 4 and below the aluminum thin film 7 joined to the upper glass stopper (insulated from the P + diffusion wiring 11). It is connected to another voltage applying pad 16 via the diffusion wiring 11, the contact part 12, and the aluminum wiring 13.

A resist is passivated on each aluminum portion, and thereafter, the cantilever 4 is thinned by alkali anisotropic etching from the back surface of the sensor chip 1 and the periphery of the mass portion 5 is penetrated, thereby forming a U-shape. A slit 10 having a shape is formed.

Thereafter, aluminum wiring 13, pad 14 for wire bonding, upper glass stopper (not shown)
The resist formed on each of the aluminum thin film 7 and the aluminum wire bridge 28 to be bonded to the aluminum thin film 7 is removed by a plasma asher, an organic solvent or the like. The upper and lower glass stoppers (not shown) are joined by anodic bonding to the cantilever 4 thus formed and the upper and lower sides of the mass portion 5 serving as a weight.
Form an air damping structure. The bridge 28 prevents the cantilever 4 from being broken (broken) due to excessive acceleration.

Next, dicing is performed to divide into individual sensor chips 1. Then, the substrate is die-bonded with an adhesive, and the wire bonding pad 14 is electrically connected to the terminal of the substrate.

Finally, a terminal such as a probe connected to a power supply is brought into contact with the voltage applying pads 16 of the sensor chip 1 to apply a voltage between the two voltage applying pads 16, thereby forming a current path. A current is caused to flow through the aluminum wire bridge 28 through the bridge, and the bridge 28 is blown.

The bridge 28 may be blown at least in the process after the upper and lower glass stoppers (not shown) have been anodically bonded to the sensor chip 1. The closer to the final process, the more vibration, impact, etc. It is needless to say that the effect is small and the yield is improved.

Further, the voltage may be applied to the voltage applying pads 16 of the sensor chip 1 by wire bonding, and the voltage may be applied through the terminals of the substrate.

Although the wiring 11 is shown by a solid line in FIG. 1, it is hidden by an oxide film and a nitride film, which are insulating protective films, and cannot be seen. The same applies to the drawings of the following embodiments.

(Embodiment 2) In the first embodiment, the bridge 28 is formed by an aluminum wire. However, in the present embodiment, a bridge 29 is formed by a gold wire as shown in FIG. It is designed to eliminate destruction.

Since the process steps of the semiconductor acceleration sensor of this embodiment are the same as those of the fourth embodiment, the description is omitted here. However, the bridge 29 made of a gold wire formed so as to span (straddle) the slit 10 is It is formed by adjusting the thickness so as to be blown when an electric current is applied. The fusing current of this gold wire is, for example, about 0.
5A. The fusing method is performed by applying a voltage to the voltage application pads 16, 16 as in the fourth embodiment.

The gold wire bridge 29 is excellent in corrosion resistance. Therefore, it can be etched with an acid such as hydrofluoric acid to form the slit 10, and is corroded and broken even in a process such as removal of an oxide film. There is nothing.

(Embodiment 3) FIG. 3 is a plan view of this embodiment. In manufacturing a semiconductor acceleration sensor of this embodiment, first, as in the above-described conventional example, the crystal plane is (100). After the silicon single crystal wafer is oxidized to form an oxide film, only the oxide film in the region where the cantilever 4 and the mass portion 5 are to be formed in the future is removed by photolithography in a shape close to a U-shape. Next, silicon is etched using the oxide film as an etching mask. The etching depth is generally about 6 μm to 30 μm. Then, oxidation is performed again, and a P + diffusion layer is formed to make contact with the aluminum wiring. Subsequently, two gauge resistors 6 each composed of a diffusion gauge resistor are formed on the two cantilevers 4 by ion implantation so as to form a bridge with each other.

Next, aluminum sputtering and sintering (about 450 ° C.) are performed to form an aluminum wiring 13, a pad 14 for wire bonding, and a pad 1 for voltage application.
Aluminum thin films to be the thin film bridges 17 are formed at portions corresponding to slits 6 and 16 and slits described later.

At this time, an aluminum wiring 13 is connected to the P + diffusion wiring 11 connected to the gauge resistor 6 by a contact portion 12, and this aluminum wiring 13 is formed on the periphery of the sensor chip 1 of the semiconductor acceleration sensor by wire bonding. Connected to the pad 14.

Further, an aluminum thin film 7 joined to an upper glass stopper (not shown) is simultaneously formed on the oxide film and the nitride film, which are insulating protective films on the P + diffusion wiring 11.

The aluminum thin film bridge 17 formed at the position corresponding to the slit 10 is thin and thin so that it is blown when an electric current is applied. Since the current density of the aluminum is ^{1 × 10 5 A / cm 2} , if it for example by a thickness of about 5000 Å, the number μm~ about 10μm width, can be blown in only by applying a voltage of several 10V.
The aluminum thin film bridge 17 may be provided at one or more locations. Both ends of the aluminum thin film bridge 17 are connected between the voltage application pads 16 through the aluminum wiring 13 and the P + diffusion wiring 11. The aluminum wiring 13 and the P + diffusion wiring 11 are connected by a contact portion 12.

Next, a nitride film or a resist is passivated on the aluminum portion. Then, the cantilever 4 is thinned by alkali anisotropic etching from the back surface of the sensor chip 1 of the semiconductor acceleration sensor, and the mass 5
A slit 10 having a shape close to a U-shape is formed by penetrating the periphery.

At this time, a thin film bridge 17 made of aluminum is formed as shown in FIG. 4 so as to span (straddle) the slit 10.

Thereafter, a nitride film or a resist formed on each of the aluminum wiring 13, the wire bonding pad 14, the aluminum thin film 7 to be bonded to the glass stopper 2, and the aluminum thin film bridge 17 is coated with a plasma asher, Remove with buffered hydrofluoric acid, organic solvent, etc. The upper and lower glass stoppers are joined to the cantilever 4 thus formed and the upper and lower sides of the mass portion 5 by anodic bonding to form an air damping structure. And thin film bridge 1
Numeral 7 prevents breakage (breaking) due to excessive acceleration applied to the cantilever 4.

Next, dicing is performed to divide into individual sensor chips 1. Then, the substrate is die-bonded with an adhesive, and the wire bonding pad 14 is electrically connected to the terminal of the substrate.

Finally, a terminal such as a probe connected to a power supply is brought into contact with the voltage applying pads 16 of the sensor chip 1 to apply a voltage between the two voltage applying pads 16, thereby forming a current path. Through the aluminum thin film bridge 1
7, a current is passed through the thin film bridge 17 to blow it. Here, when a voltage is applied between the voltage applying pads 16 of the chip sensor 1 to blow the thin film bridge 17, at least the steps after the upper and lower glass stoppers (not shown) are anodic-bonded to the sensor chip 1. However, it goes without saying that the closer to the final step, the less the effects of vibration, impact, etc., and the better the yield.

The voltage may be applied to the voltage applying pads 16 of the sensor chip 1 by wire bonding and the voltage may be applied through the terminals of the substrate. (Embodiment 4) FIGS. 5 and 6 show this embodiment.
The process steps before the aluminum spatter are substantially the same as those in the first embodiment, and the description of the subsequent steps, which are substantially the same steps and structures, will be omitted.

As shown in FIG. 5, the aluminum thin film bonded to the upper glass stopper 2 shown in FIG. 6 is formed by two electrically separated regions 7a and 7b in a state of being diced and divided into individual chips. I do. Also, an aluminum thin film bridge 17 is formed so as to span (straddle) the slit 10,
One end of the thin film bridge 17 is connected to the aluminum thin film 7b joined to the upper glass stopper 2 by the aluminum wiring 13, and the other end is connected to the P + diffusion wiring 11 (or the aluminum wiring 1).
According to 3), the aluminum thin film 7a to be joined to the upper glass stopper 2 is connected via the contact portion 12.

The upper glass stopper 2 and the sensor chip 1
The aluminum thin films 7a and 7b formed on the wafer surface are bonded by an anodic bonding method. At this time, aluminum is laminated on the scribe lane on the outer periphery of the sensor chip 1, and the aluminum thin films 7a and 7b is electrically connected at the time of anodic bonding, and has the same potential even when a high temperature (about 400 ° C.) and a high voltage of about 600 V to 800 V are applied in the anodic bonding step. Is not blown. When the scribe lane is cut in the dicing in the next step, the aluminum thin films 7a and 7b are electrically separated.

The upper glass stopper 2 is so formed that a part of the surface of the aluminum thin films 7a and 7b to be joined thereto is exposed.
Notch portions 19 for voltage application are provided.

In the final step of the assembling process, a voltage is applied between the notch portions for voltage application 19, 19, so that a current flows to the aluminum thin film bridge 17 formed in the slit 10 through the current path, and Fuse bridge 17,
The cantilever 4 is made movable. (Embodiment 5) In Embodiment 3, the thin film bridge 17 made of an aluminum thin film is formed in the slit 10, but in this embodiment, as shown in FIG. 7, the thin film bridge 20 made of a gold thin film is formed by sputtering or vapor deposition. Slit 10
The wiring passing in the vicinity is referred to as a gold wiring 21. Then, after dicing the individual chips, a voltage is applied to the thin film bridge 17 in the slit 10 from the voltage applying pad 16, the thin film bridge 20 is blown, and the cantilever 4 is made movable.

In the process of the semiconductor acceleration sensor according to the present embodiment, the cantilever 4 is thinned by alkali anisotropic etching from the back surface of the sensor chip 1 and the periphery of the mass portion 5 is penetrated so as to have a substantially U-shape. After forming the slit 10 having the shape, the aluminum wiring 13 and the gold wiring 2 are formed.
1, a bonding pad 14, a voltage applying pad 16, an aluminum thin film 7 bonded to an upper glass stopper (not shown), and a nitride film or a resist formed on a thin film bridge 20 of a gold thin film. Remove with Asher, buffered hydrofluoric acid, organic solvent, etc.

The anisotropically etched portion of the cantilever 4 was further etched isotropically with a hydrofluoric acid to a depth of several μm or less to make the cantilever 4 thinner. In order to improve the strength of the cantilever 4, the aluminum thin film bridge is eroded by the hydrofluoric acid, but the gold thin film bridge 20 is not corroded by the hydrofluoric acid.
(See FIG. 4).

In addition, since the gold wiring 21 has excellent corrosion resistance, even if moisture enters the cavity of the air damping structure to which the upper and lower glass stoppers (not shown) are joined, it corrodes. There is nothing.

(Embodiment 6) In Embodiments 3 to 5, the thin film bridge 17 or 20 made of an aluminum thin film or a gold thin film is formed to eliminate breakage during the assembling process of the cantilever 4. In this embodiment, as shown in FIGS. 8 and 9, a two-layer thin film bridge 25 made of aluminum and gold is formed so as to extend over the slit 10 and is blown.

In manufacturing the semiconductor acceleration sensor of this embodiment, a silicon single crystal wafer having a (100) crystal plane is first oxidized to form an oxide film as in the first embodiment, and then a cantilever is formed in the future. Only the oxide film in the region where the mass 4 and the mass portion 5 are to be formed is formed by the photolithography technique.
Remove in a shape close to a U-shape. Next, silicon is etched using the oxide film as an etching mask. The etching depth is generally about 6 μm to 30 μm. Then, oxidation is performed again, and a P + diffusion layer is formed to make contact with the aluminum wiring. Subsequently, two gauge resistors 6 each composed of a diffusion gauge resistor are formed on the two cantilevers 4 by ion implantation so as to form a bridge with each other.

Next, aluminum sputtering and sintering (about 450 ° C.) are performed to form an aluminum wiring 13, a wire bonding pad 14, and a voltage application pad 1.
Bridges 25a made of an aluminum thin film are formed at portions corresponding to the slits 6, 6 and 16 described later. This bridge 25a is a lower layer of the thin-film bridge 25 having a two-layer structure.

At this time, the aluminum wiring 13 is connected to the contact portion 12 with respect to the P + diffusion wiring 11 connected to the gauge resistor 6.
Connected by The other end of the aluminum wiring 13 is connected to a wire bonding pad 1 formed around the sensor chip 1.
4 is connected.

The aluminum thin film 7 to be joined to the upper glass stopper (not shown) is formed on an oxide film and a nitride film which are insulating protective films on the P + diffusion wiring 11. Then, gold is sputtered or vapor-deposited, and a bridge 25b is formed of a gold thin film at a portion corresponding to the gold wiring 21 and the slit 10.
The bridge 25b is an upper layer of the thin-film bridge 25 having a two-layer structure.

Here, the bridge 25a made of an aluminum thin film
Are formed to have a small thickness and a small width so that they are melted when a current is applied. Since the current density of the aluminum is 1 × 10 ⁵ A / cm ² as described above, thereby for example a thickness of about 5000 Å, the number μm~ about 10μm width
In this case, the fusing can be performed only by applying a voltage of several tens of volts between both ends. This aluminum thin film bridge 25a may be provided at one or more locations.

Next, a nitride film or a resist is passivated on the aluminum portion. Then, the cantilever 4 is removed from the back surface of the sensor chip 1 by alkali anisotropic etching.
And a slit 10 having a shape close to a U-shape is formed as shown in FIG. At this time, the thin film bridge 25 formed by the bridges 25a and 25b is formed so as to span (straddle) the slit 10.

Thereafter, the aluminum wiring 13, the wire bonding pad 14, the voltage applying pad 16, the aluminum thin film 7 bonded to the upper glass stopper (not shown), the nitride film or the resist formed on the aluminum thin film bridge 25a. Is removed with a plasma asher, buffered hydrofluoric acid, an organic solvent or the like. Upper and lower glass stoppers (not shown) are joined to the cantilever 4 thus formed and the upper and lower sides of the mass portion 5 by anodic bonding to form an air damping structure. Here, the thin film bridge 25 is broken (broken) due to excessive acceleration applied to the cantilever 4.
To prevent

Next, dicing is performed to divide into individual sensor chips 1. Then, the substrate is die-bonded with an adhesive to electrically connect the wire bonding pads 14 to the terminals of the substrate.

Finally, the sensor chip 1 is heated to about 150 ° C. or more. The heating time is, for example, 24 hours or more.

Then, in the thin film bridge 25 of gold and aluminum, a brittle intermetallic compound is formed at the bonding interface between gold and aluminum. Then, a terminal such as a probe connected to a power supply is brought into contact with the voltage application pads 16, 16 of the sensor chip 1, and a voltage is applied between the pads 16, 16 so that the voltage is applied to the gold via the conduction path. Aluminum thin film bridge 25
When the current flows through the thin film bridge 25, the thin film bridge 25 is easily blown, and the cantilever 4 is made movable by the blow. Here, when a voltage is applied to the voltage application pads 16 of the sensor chip 1 and the thin film bridge 25 is blown, at least the upper and lower glass stoppers (not shown) are used for the sensor chip 1.
It is sufficient that the process be performed after the anodic bonding, but it goes without saying that the closer to the final process, the less the effects of vibration, impact, etc., and the better the yield.

The voltage may be applied to the voltage application pad 16 of the sensor chip 1 by wire bonding via a terminal of the substrate.

One end of the thin film bridge 25 is connected to one of the voltage applying pads 16 through the aluminum thin film 7 joined to the upper glass stopper, and the other end is connected to the cantilever 4 from the upper surface of the mass portion 5 by a gold wire 21. Through the P + diffusion wiring 11 and below the aluminum thin film 7 joined to the upper glass stopper (insulated from the P + diffusion wiring 11) and connected to the other voltage application pad 16 I have.

(Embodiment 7) This embodiment corresponds to Embodiment 3
A thin film bridge 17 made of an aluminum thin film is formed in the same manner as described above to prevent the destruction of the cantilever 4 in the assembling process. In this embodiment, however, one end of the thin film bridge 17 is connected as shown in FIG. Aluminum thin film 7 and aluminum wiring 13 joined to upper glass stopper (not shown)
And the other end thereof is connected to one of the voltage applying pads 16 and the other end is contacted with the Si bulk of the mass section 5 by P + diffusion.
The third embodiment differs from the third embodiment in that it is connected to the other voltage application pad 16 contacted through the second contact.

Since the manufacturing process and the like are basically the same as those of the third embodiment, in the drawings, components having the same functions are denoted by the same reference numerals and symbols, and description thereof is omitted.

In this embodiment, too, dicing is performed to divide the sensor chips into individual sensor chips 1 and then die-bonded to the substrate with an adhesive to electrically connect the wire bonding pads 14 and the terminals of the substrate. Connecting.

Finally, a terminal such as a probe connected to a power supply is brought into contact with the voltage applying pads 16 of the sensor chip 1 to apply a voltage between the two voltage applying pads 16, thereby forming a current path. A current is caused to flow through the aluminum wire bridge 28 through the bridge, and the bridge 28 is blown. Here, the bridge 28 may be blown at least in the process after the upper and lower glass stoppers (not shown) are anodically bonded to the sensor chip 1. It goes without saying that the influence is small and the yield is improved.

Further, the voltage may be applied to the voltage applying pads 16 of the sensor chip 1 by wire bonding via the terminals of the substrate.

(Embodiment 7) In Embodiments 1 to 6, a bridge made of an aluminum or gold wire which can be easily blown off by an electric current or a thin film formed using a thin film or both of them is formed so as to extend over the slit 10. In this embodiment, the destruction of the cantilever 4 in the assembling process is eliminated. However, in the present embodiment, the polysilicon resistor thin film shown in FIG. The bridge 23 is formed so as to extend over the slit 10.

The manufacturing process of this embodiment is basically the same as that of each of the above embodiments.
After oxidizing the silicon single crystal wafer of 0) to form an oxide film, only the oxide film in a region where a cantilever and a mass portion are to be formed in the future is removed by a photolithography technique in a shape close to a U-shape. Next, silicon is etched using the oxide film as an etching mask. The etching depth is
Generally, it is about 6 μm to 30 μm. Oxidation is performed again, and a P + diffusion layer is formed to make contact with the aluminum wiring. Subsequently, two diffusion gauge resistors are formed on the two cantilevers 4 by ion implantation so as to form a bridge with each other.

Next, on the oxide film and the nitride film, which are insulating protective films on the P + diffusion wiring, a poly-junction bonded to an upper glass stopper (not shown) bonded to an upper glass stopper (not shown). A bridge 23 is formed by a poly-Si thin-film resistor at a position corresponding to the Si thin film 24 and the slit 10.
The thickness of the poly-Si thin film constituting the bridge 23 is about 5
Reduced pressure CVD method at a temperature of 600 to 650 ° C at 000 ° C (100% SiH ₄ is decomposed at a gas pressure of 20 to 200 Pa)
Formed by The poly-Si thin film resistor is
A thin film is formed by doping B or As. Other than this poly Si thin film, single crystal Si or alpha moss Si may be used.

Further, aluminum sputtering, sintering (about 450 ° C.) is performed to form an aluminum wiring 13, a wire bonding pad 14, and a voltage application pad 16. At this time, an aluminum wiring 13 was connected to a P + diffusion wiring 11 connected to a diffusion gauge resistance (hereinafter referred to as a gauge resistance) 6 at a contact portion 12, and this aluminum wiring 13 was formed on the periphery of the sensor chip 1. It is connected to the pad 14 for wire bonding.

The bridge 23 made of a poly-Si resistive thin film is
It is formed to have a small thickness and a small width so that it is melted when a current is applied. The resistivity of this bridge 23 is 2
It is from × 10 ⁻³ Ω · cm to 5 × 10 ⁻³ Ω · cm. From this, the thickness and width are designed. Bridge 23 is 1
It is sufficient to provide more than the number of places.

Next, a nitride film or a resist is passivated on the aluminum portion. Then, the cantilever 4 is made thinner by alkali anisotropic etching from the back surface of the sensor chip 1 and penetrates around the mass portion 5 to form a slit 10 having a substantially U-shape. At this time, a bridge 23 made of a poly-Si resistance thin film is formed so as to span (straddle) the slit 10.

Here, one end of the bridge 23 is connected to the voltage applying pad 16 through a poly-Si thin film 24 joined to an upper glass stopper (not shown), and the other end is connected to the Si bulk of the mass portion 5 and the P + It is contacted by diffusion and is connected to a voltage application pad 16 that has contacted another Si bulk.

After that, a poly-Si thin film to be joined to an aluminum wiring, a bonding pad, a glass stopper, a poly-S
The nitride film or the resist formed on the bridge 23 of the i-resistance thin film is removed with a plasma asher, buffered hydrofluoric acid, an organic solvent, or the like. The upper and lower glass stoppers (not shown) are joined to the cantilever thus formed and the upper and lower sides of the mass portion 5 by anodic bonding.
Form an air damping structure. Here bridge 23
Prevents the cantilever 4 from being broken (broken) due to excessive acceleration.

Next, dicing is performed to divide the individual sensor chips 1. Then, the substrate is die-bonded with an adhesive to electrically connect the wire bonding pads 14 to the terminals of the substrate.

Finally, by applying a voltage to the voltage application pads 16 of the sensor chip 1 by contacting the terminals of a probe or the like connected to a power supply, a bridge of the poly-Si resistance thin film is formed through a current path. An electric current is applied to the bridge 23 to blow the bridge 23.

Here, when the voltage is applied to the voltage application pads 16 of the sensor chip 1 to blow the bridge 23, at least the upper and lower glass stoppers (not shown)
May be any process after the anodic bonding to the sensor chip 1, but it goes without saying that the closer to the final process, the less the effects of vibration, impact, etc., and the better the yield.

The voltage may be applied to the voltage applying pad 16 by wire bonding, and the voltage may be applied via the terminal of the substrate.

(Embodiment 8) In this embodiment, a thin film bridge 17 made of an aluminum thin film is formed in the same manner as in Embodiment 3,
Although the destruction of the cantilever 4 in the assembling process is eliminated, the feature is that an aluminum wiring 13 ′ is provided on the inclined surface of the mass portion 5 in order to apply a voltage to the thin film bridge 17.

The manufacturing process of this embodiment is similar to that of the third embodiment. First, a silicon single crystal wafer having a (100) crystal plane is oxidized to form an oxide film, and then a cantilever 4 and a mass portion 5 are formed in the future. Only the oxide film in the region to be removed is removed by photolithography in a shape close to a U-shape. Next, silicon is etched using the oxide film as an etching mask. Etching depth is generally 6 μm to 30 μm
m. Then, oxidation is performed again, and a P + diffusion layer is formed to make contact with the aluminum wiring. Subsequently, two gauge resistors 6 each composed of a diffusion gauge resistor are formed on the two cantilevers 4 by ion implantation so as to form a bridge with each other.

Next, from the front side of the wafer, aluminum sputtering and sintering (about 450 ° C.) were performed to form an aluminum wiring 13, a wire bonding pad 14, voltage application pads 16, 16, and a thin film bridge 17. An aluminum thin film is formed.

At this time, an aluminum wiring 13 is connected to the P + diffusion wiring 11 connected to the gauge resistor 6 by a contact portion 12, and the aluminum wiring 13 is formed by a wire bonding formed around the sensor chip 1 of the semiconductor acceleration sensor. Connected to the pad 14.

Further, an aluminum thin film 7 joined to the upper glass stopper 2 is simultaneously formed on the oxide film and the nitride film which are the insulating protective films on the P + diffusion wiring 11.

The aluminum thin film serving as the thin film bridge 17 formed at a position corresponding to the slit 10 is formed to have a small thickness and a small width so that the aluminum thin film is melted when an electric current is applied. As described above, the current density of aluminum is 1 × 10 ⁵ A
/ Cm ² , so that the thickness is about 50
If the width is set to several μm to about 10 μm, fusing can be performed only by applying a voltage of several tens of volts. This thin film bridge 1
The aluminum thin film 7 may be provided at one or more locations.

Next, a nitride film or a resist is passivated on the aluminum portion. Then, the cantilever 4 is thinned by alkali anisotropic etching from the back surface of the sensor chip 1 of the semiconductor acceleration sensor, and the mass 5
A slit 10 having a shape close to a U-shape is formed by penetrating the periphery. At this time, a thin film bridge 17 made of an aluminum thin film is formed as shown in FIG.

Next, from the back side of the wafer, aluminum sputtering is performed to join the aluminum thin film 7 to the lower glass stopper 3.
An aluminum wiring 13 ′ connected to the thin film bridge 17 is formed on the back surface of the cantilever 4 and the inclined surface of the mass portion 5.

Thereafter, the nitride film 9 formed on the aluminum wiring 13, 13 ', the pad 14 for wire bonding with the wire 15, the aluminum thin film 7 bonded to the glass stopper 2, and the aluminum thin film bridge 17, Is removed with a plasma asher, buffered hydrofluoric acid, an organic solvent, or the like. Glass stoppers 2 and 3 are joined to the cantilever 4 thus formed and the upper and lower sides of the mass portion 5 by anodic bonding to form an air damping structure. Here, the thin film bridge 17 prevents breakage (breaking) due to excessive acceleration applied to the cantilever 4.

A metallized through wiring 26 is formed on the front and back surfaces of the lower glass stopper 3 with a metal such as aluminum, gold, Ti or Ni. The electrode pad 16 'for applying a voltage is formed at both ends of the thin film bridge 17 formed so as to extend over the slit 10. The metallized through wiring 26 of the lower glass stopper 3 is electrically connected to the lower glass bonding aluminum thin film 7 on the back surface of the wafer.

Next, dicing is performed to divide into individual sensor chips 1. Then, the substrate is die-bonded with an adhesive, and the wire bonding pad 14 is electrically connected to the terminal of the substrate by a wire 15.

Finally, the terminal 27 of the substrate connected to the electrode pad 16 ′ for voltage application of the lower glass stopper 3 is
A voltage is applied to cause a current to flow through the thin film bridge 17 to blow the thin film bridge 17. Here, the time when the thin film bridge 17 is blown is determined by at least the upper and lower glass stoppers 2,
The step 3 may be any step after the anodic bonding to the sensor chip 1, but it goes without saying that the closer to the final step, the less the influence of vibration and impact, and the better the yield.

Further, the voltage may be applied through the terminals of the substrate by wire bonding to the voltage application pads 16 of the sensor chip 1.

[0101]

According to the first aspect of the present invention, a mass portion, a sensor chip provided so as to surround the mass portion via a slit, and the sensor chip and the mass portion are connected by an elastic beam. In a method of manufacturing a semiconductor acceleration sensor in which a support for supporting a mass portion and a gauge resistor formed on the support and a glass stopper on each surface of the sensor chip are provided, at least one outer periphery of the mass portion And the sensor chip are fixed with a bridge of a low-resistance metal wire formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for flowing a current through the low-resistance metal wire is provided in the sensor chip. After bonding the glass stoppers to both surfaces of the sensor chip, the individual sensor chips are diced, and after the dicing, voltage is applied to both ends of the low-resistance metal wire via current paths. As a result, a current is caused to flow through the low-resistance metal wire to blow the low-resistance metal wire, so that a glass stopper is joined and a current is applied to the low-resistance metal wire in the final assembly state in which a damping structure is formed. Can be cut, so that in the assembling process, the cantilever can be moved without being damaged, and as a result, the assembling process becomes easier, and the yield is improved,
As a result, it is possible to provide a very small, high-sensitivity semiconductor acceleration sensor at a low cost, and furthermore, because it is fusing by an electric current, it does not generate flying objects or particles, There is an effect that no dust is generated.

According to the second aspect of the present invention, in the first aspect of the present invention, since the low-resistance metal wire is an aluminum wire,
In addition to the effects of the first aspect, the manufacturing cost is reduced.

According to the third aspect of the present invention, since the low-resistance metal wire is a gold wire in the first aspect of the invention, in addition to the effect of the first aspect of the present invention, the low resistance metal wire has excellent corrosion resistance. There is no rupture due to corrosion in the process such as film removal.

According to the fourth aspect of the present invention, the mass portion, the sensor chip provided so as to surround the mass portion through the slit, and the sensor chip and the mass portion are connected by an elastic beam. In a method of manufacturing a semiconductor acceleration sensor in which a support supporting the mass portion, a gauge resistor formed on the support, and a glass stopper on each side of the sensor chip, at least one outer periphery of the mass portion, The sensor chip is fixed with a thin-film bridge of a low-resistance metal thin film formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for flowing a current through the thin-film bridge is provided in the sensor chip. After bonding glass stoppers to both surfaces of the chip, individual sensor chips are diced, and after the dicing, voltage is applied to both ends of the thin film bridge via current paths. Blown the thin film bridge by applying a current to the thin film bridge, since the support and movable,
In the final assembly state where the glass stopper is joined and the damping structure is formed, the thin-film bridge of the low-resistance metal thin film can be cut by electric current, so that the cantilever can be moved without being damaged in the assembly process. , Resulting in easier assembly process, higher yield,
As a result, it is possible to provide a very small and highly sensitive semiconductor acceleration sensor at low cost, and furthermore, because it is fusing by electric current, it does not generate scattered objects or particles, or There is an effect that no dust is generated.

According to the fifth aspect of the present invention, in the fourth aspect of the present invention, the thin film bridge is made of an aluminum thin film. It can be used and the manufacturing cost is low.

According to the sixth aspect of the present invention, in the fourth aspect of the present invention, the thin film bridge is made of a gold thin film. There is no rupture due to corrosion.

According to a seventh aspect of the present invention, in the fourth aspect, the thin film bridge is formed by a two-layer structure of a gold thin film and an aluminum thin film.
Since the heat of 0 ° C. or more is applied, the effect of the invention of claim 4 is obtained.

According to the eighth aspect of the present invention, the mass portion, the sensor chip provided so as to surround the mass portion via the slit, and the sensor chip and the mass portion are connected by an elastic beam. In a method of manufacturing a semiconductor acceleration sensor in which a support supporting the mass portion, a gauge resistor formed on the support, and a glass stopper on each side of the sensor chip, at least one outer periphery of the mass portion, The sensor chip is fixed with a bridge made of a polysilicon resistive thin film formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for flowing current through the bridge is provided in the sensor chip. After the glass stoppers are bonded to both sides of the bridge, the individual sensor chips are diced, and after the dicing, voltage is applied to both ends of the bridge via current paths. A current is caused to flow through the bridge to blow the bridge and make the support movable, so that the bridge made of the polysilicon resistive thin film is cut by the current in the final assembly state where the glass stopper is joined and the damping structure is formed. Therefore, in the assembling process, the cantilever can be made movable without being damaged, and as a result, the assembling process is facilitated, and the yield is improved.
As a result, it is possible to provide a very small, high-sensitivity semiconductor acceleration sensor at a low cost, and furthermore, because it is fusing by an electric current, it does not generate flying objects or particles, There is an effect that no dust is generated.

[Brief description of the drawings]

FIG. 1 is a top view of a sensor chip according to a first embodiment of the present invention.

FIG. 2 is a top view of a sensor chip according to a second embodiment of the present invention.

FIG. 3 is a top view of a sensor chip according to Embodiment 3 of the present invention.

FIG. 4 is an enlarged sectional view of a main part of the above.

FIG. 5 is a top view of a sensor chip according to a fourth embodiment of the present invention.

FIG. 6 is a top view of the sensor chip after the upper glass stopper is bonded thereto.

FIG. 7 is a top view of a sensor chip according to a fifth embodiment of the present invention.

FIG. 8 is a top view of a sensor chip according to Embodiment 6 of the present invention.

FIG. 9 is an enlarged sectional view of a main part of the above.

FIG. 10 is a top view of a sensor chip according to a seventh embodiment of the present invention.

FIG. 11 is a top view of a sensor chip according to Embodiment 8 of the present invention.

FIG. 12 is a sectional view of Embodiment 9 of the present invention.

FIG. 13 is a sectional view of a conventional example.

FIG. 14 is a top view of the same sensor chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor chip 4 Cantilever 5 Mass part 6 Gauge resistance 7 Aluminum thin film 10 Slit 11 P + Diffusion layer wiring 12 Contact part 13 Aluminum wiring 14, 14 'Wire bonding pad 16 Voltage application pad 28 Aluminum wire bridge

Claims (8)

[Claims] 1. A mass part, a sensor chip provided so as to surround the mass part via a slit, and an elastic beam connecting the sensor chip and the mass part to support the mass part. In a method for manufacturing a semiconductor acceleration sensor in which a support, a gauge resistor formed on the support, and a glass stopper are bonded to both surfaces of the sensor chip, at least one outer periphery of the mass portion and the sensor chip, The sensor chip is fixed with a bridge of a low-resistance metal wire formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for flowing a current through the low-resistance metal wire is provided on the sensor chip. After joining the stopper, the individual sensor chips are diced, and after the dicing, the low-resistance metal wires are applied to both ends of the low-resistance metal wires through current-carrying paths. The method of manufacturing a semiconductor acceleration sensor, characterized in that by applying a current to the anti-metal wire to blow the low-resistance metal wire, the support and movable. 2. The method according to claim 1, wherein the low resistance metal wire is an aluminum wire. 3. The method according to claim 1, wherein the low-resistance metal wire is a gold wire. 4. A mass part, a sensor chip provided so as to surround the mass part via a slit, and an elastic beam connecting the sensor chip and the mass part to support the mass part. In a method for manufacturing a semiconductor acceleration sensor in which a support, a gauge resistor formed on the support, and a glass stopper are bonded to both surfaces of the sensor chip, at least one outer periphery of the mass portion and the sensor chip, The sensor chip is fixed with a thin-film bridge of a low-resistance metal thin film formed so as to extend over a slit between the mass portion and the sensor chip, and an electric current path for flowing a current through the thin-film bridge is provided on the sensor chip. After joining the stopper, the individual sensor chips are diced, and after the dicing, the thin film bridges are applied to both ends of the thin film bridge through current paths. The method of manufacturing a semiconductor acceleration sensor blown the thin film bridge by applying a current, characterized in that the support and movable. 5. The method according to claim 4, wherein the thin film bridge is made of an aluminum thin film. 6. The method according to claim 4, wherein the thin film bridge is made of a gold thin film. 7. The thin film bridge is formed by a two-layer structure of a gold thin film and an aluminum thin film, and heat of about 150 ° C. or more is applied when fusing the thin film bridge.
A manufacturing method of the semiconductor acceleration sensor according to the above. 8. A mass part, a sensor chip provided so as to surround the mass part via a slit, and an elastic beam connecting the sensor chip and the mass part to support the mass part. In a method for manufacturing a semiconductor acceleration sensor in which a support, a gauge resistor formed on the support, and a glass stopper are bonded to both surfaces of the sensor chip, at least one outer periphery of the mass portion and the sensor chip, The sensor chip is fixed with a bridge made of a polysilicon resistive thin film formed so as to extend over a slit between the mass portion and the sensor chip, and a current path for supplying current to the bridge is provided on the sensor chip. After bonding, the individual sensor chips are diced, and after the dicing, voltage is applied to both ends of the bridge via current-carrying paths. The method of manufacturing a semiconductor acceleration sensor, characterized in that by supplying a flow blown to the bridge, the support and movable.