JP3481399B2 - Pressure sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strain gauge type semiconductor pressure sensor. 2. Description of the Related Art Conventionally, as this type of pressure sensor, there is one disclosed in Japanese Utility Model Laid-Open No. 3-88137. As shown in FIG. 12, a silicon substrate A provided with a plate-shaped diaphragm A1 by locally forming a thin film as shown in FIG. 12 and a glass substrate bonded to the substrate A opposed to the diaphragm A1 ( A joining member) B, and the pressure change is detected by the amount of deflection of the diaphragm A1 due to the pressure from the opposite surface A3 opposite to the opposite surface A2 to the glass substrate B. Specifically, the diaphragm is A1, SiO ₂ film A4 is formed on the opposite surface A2 with its glass substrate B. [0003] Generally, this type of pressure sensor involves heating when the glass substrate B and the substrate A are joined, so that the heat is dissipated and the opposing space A5 between the glass substrate B and the diaphragm A1 is released.
Is reduced in pressure. Then, when the diaphragm A1 receives an external pressure from the opposite surface A3 during this joining, the diaphragm A1 easily bends toward the glass substrate B and joins with the glass substrate B, so that the pressure sensor cannot be manufactured. The diaphragm disclosed in Japanese Unexamined Patent Publication No. 3-88137 has a diaphragm.
Since the SiO ₂ film A4 is formed on the surface A2 of A1 facing the glass substrate B, the pressure sensor can be manufactured without bonding to the glass substrate B. In the conventional pressure sensor described above, the diaphragm A1 is, as described above,
Since the SiO ₂ film A4 is formed on the surface A2 facing the glass substrate B, the SiO ₂ film A4 is not bonded to the glass substrate B, so that a pressure sensor can be manufactured. However, since a relatively complicated process of forming the SiO ₂ film A4 on the surface A2 of the diaphragm A1 facing the glass substrate B is required, the production is troublesome. The present invention has been made in view of the above points, and an object of the present invention is to provide a pressure sensor which can be reliably manufactured without any trouble. [0007] In order to solve the above-mentioned problems, the present invention is characterized in that a silicon substrate provided with a plate-like diaphragm formed locally thinly is provided. An opposing member disposed opposing the diaphragm,
A package for accommodating the substrate together with the opposing member to be joined, wherein the pressure sensor detects a pressure change by a flexure amount of the diaphragm caused by receiving a pressure from a surface opposite to the opposing surface with the opposing member. At least one of the member and the package is provided with a communication hole communicating with an opposing space between the diaphragm and the diaphragm from an outer surface, and excessive pressure is transmitted to the opposing member to bend the diaphragm. and a configuration in which contact may protrusion is provided on its diaphragm <br/> by. Therefore, in the facing space between the facing member and the diaphragm, since a communication hole communicating with the facing space is provided through the facing member or the outer surface of the package, heating is performed when the facing member and the package are joined. Even with this, the opposed space is not decompressed with heat radiation, and even if the diaphragm receives an external pressure from the surface opposite to the opposed member, the diaphragm bends toward the opposed member and joins with the opposed member. Is eliminated, and it can be manufactured reliably. Moreover, it is not a comparatively complicated process of forming an SiO2 film on the surface of the diaphragm facing the glass substrate as in the conventional example, but rather providing a communicating hole from the outer surface to the facing space in the facing member or package. Since only a simple process is required, the production does not take much effort. Further, when excessive pressure is transmitted and the diaphragm bent toward the opposing member comes into contact with the opposing member via the protrusion, and when the deflection is regulated, the height of the protrusion provided on the opposing member is increased. By changing, the amount of deflection can be adjusted. A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. . Reference numeral 1 denotes an n-type silicon substrate having both sides polished and having a crystal orientation (100) plane. The bonding member 2 side described later is anisotropically etched with KOH or NaOH to form a bonding member 2. Opposing surface 1a that faces
Is provided on the bottom surface. The bottom of the recess 1b is a made of a diaphragm 1c described later, Si
O ₂ Is ion-implanted or thermally diffused by using as a mask, thereby providing a strain gauge resistor 1d. Also,
This substrate 1 is provided with a wiring pattern (not shown) and electrode pads 1e by vacuum evaporation of Al. The electrode pad 1e is connected to a wiring pattern provided on an external substrate (not shown) by wire bonding with an Au line or an Al line. Next, the bottom of the concave portion 1b is formed on the side opposite to the opposing surface 1a by using SiN or SiO ₂ as a mask.
The plate-shaped diaphragm 1c is formed by being locally thinned by etching with a 5% KOH aqueous solution. The diaphragm 1c has an SiO ₂ film (not shown) on an opposite surface 1f opposite to the opposite surface 1a.
Is coated. Note that a SiN film may be coated. Next, the substrate 1, the bonding member 2 and the pedestal 3, which will be described later, are bonded by anodic bonding. Specifically, the substrate 1 is used as an anode, the bonding member 2 and the pedestal 3 are used as negative electrodes, and
In a vacuum atmosphere of 0 ° C., a DC voltage of about 400 to
By applying 600 V, anodic bonding is performed. Thus, the diaphragm 1c of the substrate 1 faces the bonding member 2 with the facing space 1g therebetween. The joining member 2 is made of hard glass and has a thickness of about 0.1 mm.
A communication hole 2a formed to a thickness of 3 to 0.6 mm and communicating with an opposing space 1g between the diaphragm 1c and the diaphragm 1c is pierced by vibrating a pin. The reference pressure of the atmospheric pressure is applied to the facing surface 1a of the diaphragm 1c. As shown in FIGS. 1 and 2, the communication hole 2a of the joining member 2
It is provided at a place different from the place where it comes into contact with the diaphragm 1c. The pedestal 3 is a pressure sensor chip together with the substrate 1.
10. The hard glass is used to form about 0.1.
A pressure introducing hole 3a formed to a thickness of 5 to 2 mm and reaching the opposite surface 1f side of the substrate 1 is provided by a so-called ultrasonic machining method or an electric discharge machining method in which a pin is vibrated to form a hole. By introducing a gas or a liquid into the pressure introduction hole 3a,
Pressure is transmitted to the diaphragm 1c of the substrate 1. As described above, the diaphragm 1c is in a state where the reference pressure of the atmospheric pressure is applied to the opposed surface 1a, and the pressure is transmitted by introducing the gas or the liquid to the opposite surface 1f, and the diaphragm 1c is
Bends, the opposite surface 1f with its strain gauge resistance 1d
Can measure the pressure of the gas or liquid transmitted to it. When an excessive pressure is transmitted to the opposite surface 1f of the diaphragm 1c, the diaphragm 1c is bent as its opposite surface 1a contacts the joining member 2 as shown in FIG. Is regulated, so breakage due to excessive bending
Breakage is prevented. In such a pressure sensor, the joining member 2
The opposing space 1g between the diaphragm 1c and the
Since the communication hole 2a communicating with 1g is provided to penetrate from the outer surface of the joining member 2, even when heating is performed at the time of joining the joining member 2 and the substrate 1, the facing space 1g is decompressed with heat radiation. Even if the diaphragm 1c receives an external pressure from the opposite surface 1f opposite to the facing surface 1a between the joining member 2 and the diaphragm 1c, the diaphragm 1c may bend toward the joining member 2 and join with the joining member 2. It can be manufactured reliably. Moreover, unlike the conventional example, a relatively complicated process of forming an SiO ₂ film on the surface of the diaphragm 1c facing the glass substrate is not a relatively complicated process, but the connecting member 2 is provided with a communication hole 2a communicating from the outer surface to the facing space. It requires only a relatively simple process, so that production is not troublesome. Further, since the diaphragm 1c is coated with SiO ₂ on the opposite surface 1f opposite to the opposite surface 1a, even if pressure is transmitted by a corrosive fluid such as water, oil, gas, etc. You won't have to. Further, since the communication hole 2a is provided at a location different from the location at which the diaphragm 1c is in contact with the diaphragm 1c, the diaphragm 1c reliably contacts the joining member 2 when excessive pressure is transmitted and flexes. The contact is restricted in bending, so that destruction due to excessive bending is prevented. Next, a second reference example related to the present invention is shown in FIG.
This will be described below based on Incidentally, members having the first reference example substantially the same function are denoted by the same reference numerals, the first
Only the differences from the reference example will be described. In the first embodiment , the facing space 1g is formed by providing the recess 1b in the substrate 1, but in the present embodiment , the facing space 1g is formed by providing the recess 2b in the joining member 2. I have. More specifically, the concave portion 2b is provided in the bonding member 2 by mechanical polishing or chemical etching using hydrofluoric acid or the like. In such a pressure sensor, in addition to the effect of the first reference example , the joining member 2 is locally formed to be thin like the substrate 1 so that the plate-like diaphragm 1c is formed. Since it is not necessarily provided, it is not necessary to process it as carefully as when the concave portion 1b is provided in the substrate 1 to form the facing space 1g, and the production becomes easier than in the first reference example . Next, a third reference example related to the present invention is shown in FIG.
This will be described below with reference to FIG. Incidentally, members having the first reference example <br/> substantially the same function are denoted by the same reference numerals, it referred only differs from the first embodiment. In the first reference example , the surface 2c of the joining member 2 facing the diaphragm 1c is shown.
Is flat, but in the present reference example, the projection 2d is provided. More specifically, the joining member 2 is provided with a projection 2d having a substantially flat tip surface by chemical etching using hydrofluoric acid or the like. The start position of the chemical etching is indicated by a broken line in FIG. 4 which is a plan view of the pressure sensor chip. Therefore, the diaphragm 1c is exposed to excessive pressure.
Is transmitted and bent to abut on the protrusion 2d so that cracks and the like do not occur. Further, the projection 2d is provided at a position not opposed to the strain gauge resistor 1d so that even if the diaphragm 1c is bent and abuts on the projection 2d, the projection 2d does not abut on the strain gauge resistor 1d provided on the diaphragm 1c and is damaged. ing. Note that the protrusion 2d may be provided by mechanical polishing. In such a pressure sensor, in addition to the effect of the first reference example , a diaphragm 1c, which has received excessive pressure and is bent toward the joining member 2 side, is connected to the joining member 2 via a projection 2d. When the deflection of the diaphragm 1c is adjusted by changing the height of the projection 2d provided on the joining member 2, when the deflection of the diaphragm 1c is restricted by the contact with the second member 2, the deflection of the diaphragm 1c can be adjusted. Next, a fourth reference example relating to the present invention is shown in FIG.
This will be described below based on Incidentally, like reference numerals denote members having a third reference example substantially the same function, the third
Only the differences from the reference example will be described. In the third embodiment , the joining member 2 is made of hard glass, but in this embodiment, it is made of silicon. More specifically, the joining member 2 is provided with a recess 2b and a projection 2d substantially at the center of the recess 2b by anisotropic etching. The joining member 2 is provided with a communication hole 2a from an outer surface opposite to the opposing surface 2c by anisotropic etching, plasma etching RIE, or isotropic etching using an HF aqueous solution. This joining member 2 is
When heated to 1000 ° C. in a state of polymerization with
Joined to. The substrate 1 is bonded to the pedestal 3 by anodic bonding as described above. In such a pressure sensor, in addition to the effect of the third reference example , the diaphragm 1c is made of silicon so that an excessive pressure is transmitted and the elastic bonding member is made of silicon.
Since it comes into contact with the second protrusion 2d, the impact at the time of contact is buffered, and the diaphragm 1c is not damaged. Further, since the joining member 2 is made of silicon, it can be made thinner than in the third embodiment , so that the pressure sensor itself can be downsized. In this embodiment, the joining member 2 is formed as a projection.
Although 2d is provided, for example, when it is not necessary to adjust the durability of the diaphragm 1c, the projection 2d may not be provided, in which case the processing of the joining member 2 becomes easier. Become. Also, as described above, the projections
Even when 2d is not provided, since excessive pressure is transmitted to the diaphragm 1c and the diaphragm 1c comes into contact with the elastic joining member 2 because it is made of silicon, the shock at the time of contact is buffered. As a result, damage will not occur. Next, a fifth reference example relating to the present invention will be described with reference to FIG.
This will be described below based on Incidentally, like reference numerals denote members having a third reference example substantially the same function, the third
Only the differences from the reference example will be described. In the third reference example , a projection 2d is provided on the joining member 2, whereas in this reference example, a projection 1h is provided on the substrate 1. More specifically, when the concave portion 1b is provided by anisotropic etching, the substrate 1 is provided with a projection 1h substantially at the center of the concave portion 1b. In this pressure sensor, in addition to the effect of the third reference example , the diaphragm 1c receives the excessive pressure and transmits the elastic projection 1h because it is made of silicon. Therefore, the impact at the time of contact is buffered, and the diaphragm 1c is not damaged. Next, a sixth embodiment of the present invention will be described with reference to FIGS.
This will be described below based on Incidentally, like reference numerals denote members having a fifth reference example substantially the same function, the third
Only the differences from the reference example will be described. In the fifth reference example , the protrusion
1h is made of silicon, whereas in the present reference example, it is made of metal and has elasticity. More specifically, the substrate 1 is provided with projections 1h by plating or stud bumping. When the projection 1h is provided by a plating method, for example, Au, Cu or Al
Is plated on the substrate 1. In the case where the protrusion 1h is provided by the stud bump method, for example, wire bonding is performed using an Au wire, and as shown in FIG.
1 to form a pad portion 1j and a wire portion 1k following the pad portion 1j, and cut a boundary portion between the pad portion 1j and the wire portion 1k, that is, a so-called neck portion 1m, to thereby form a projection.
1h is provided. [0039] In the such pressure sensors, in addition to the effect that it is possible to adjust the amount of bending like the effect of the first reference example <br/> and third reference example, the diaphragm 1c is excessive
Since the pressure is transmitted and comes into contact with the joining member 2 via the metal elastic projection 1h, the impact at the time of the contact is buffered, and the diaphragm 1c is damaged. No more. Next, an embodiment of the present invention will be described with reference to FIGS.
This will be described below based on Incidentally, members having the first reference example substantially the same function are denoted by the same reference numerals, the first
Only the differences from the reference example will be described. In the first reference example , the substrate
1 is joined to the joining member 2, whereas in the present embodiment, it is configured to be housed by the opposing member 4 arranged facing the diaphragm 1 c and the package 5 joined to the opposing member 4. . In FIGS. 10 and 11, the strain gauge resistance provided on the diaphragm 1c is omitted. More specifically, the substrate 1 is mounted on the bottom of a package 5 to be described later by bonding the pedestal 3 with an adhesive 5a, and its electrode pads (not shown) and external connection through the package 5 are provided. Lead wire 5b is connected by wire bonding. And this board 1
Is sealed on its opposing surface 1a side with a gel-like silicon resin 1n. As will be described later in detail, the facing member 4 is covered by covering the opening of the package 5 so as to cover the opening.
It faces the diaphragm 1c via the silicon resin 1n, and forms a facing space 1g between the diaphragm 1c and the facing space.
A communication hole 4a communicating with 1g is provided to penetrate from the outer surface. The opposing member 4 has a projection 4b on an opposing surface opposing the diaphragm 1c. The package 5 is formed of a plastic such as PPS, PBT or the like in a box shape with one opening, and the opening is covered with the facing member 4 so that the pressure sensor chip 10 and the electrode pads 1e are connected to the outside. The wire bonding portion connecting to the connection lead wire 5b is mechanically protected from external force or the like. The package 5 is provided with a communication hole 5c communicating with the opposing space and a pressure introduction hole 5d reaching the opposite surface 1f side of the substrate 1. When an excessive pressure is transmitted to the opposite surface 1f of the diaphragm 1c, the diaphragm 1c is brought into contact with the projection 4b of the opposite member 4 by the opposing surface 1a as shown in FIG. Since the bending is restricted, destruction due to excessive bending is prevented. In such a pressure sensor, the opposing member 4
The opposing space 1g between the diaphragm 1c and the
The communication holes 4a and 5c communicating with 1g are the opposing member 4 and the package.
5 through the outer surface
Even when heating is performed by soldering, welding, or the like at the time of joining the package 4 and the package 5, the opposed space is not depressurized with heat radiation, and the diaphragm 1c is opposed to the opposed surface 1a of the opposed member 4 opposite to the opposed surface 1a. Even if external pressure from 1f is received,
It does not bend toward and is not joined to the opposing member 4, and it can be manufactured reliably. Moreover, it is not a relatively complicated process of forming an SiO ₂ film on the surface of the diaphragm 1c facing the glass substrate as in the conventional example, but is connected to the facing member 1 and the package 5 from the outer surface to the facing space 1g. Since only a relatively simple process of providing the communication holes 4a and 5c is required, the production is not troublesome. Further, the excessive pressure is transmitted and the opposing member 4
The diaphragm 1c bent to the side faces the opposing member 4 via the projection 4b.
When the deflection is regulated by contacting the
By changing the height of the protrusion 4b provided on the facing member 4, the amount of bending can be adjusted. In this embodiment, the communication holes 4a and 5c are
Although provided on the opposing member 4 and the package 5, the same effect can be obtained even if provided on one of them, and in that case, the trouble of providing the communication hole is reduced,
Processing becomes easier. According to the first aspect of the present invention, the opposed member and the die
The opposing space between the diaphragm and the diaphragm communicates with the opposing space.
The communication hole penetrates from the outer surface of the facing member or package.
Since it is provided, when joining the opposing member and the package
Even when heating is applied, the opposite space is decompressed with heat radiation
And the diaphragm is opposite the surface facing the opposing member.
Deflected toward the opposing member even when receiving external pressure from the opposite surface
Eliminates joining with opposing members, ensuring production
can do. Moreover, as in the conventional example, the diaphragm
A SiO ₂ film is formed on the ram facing the glass substrate
Rather than the relatively complicated process of
A communication hole is provided in the package from the outside to the facing space.
Only requires the relatively simple process of
You will not have to make it. In addition, excessive pressure
Is transmitted and the diaphragm bent toward the opposing member
Contact with the opposing member via
At least one of the diaphragm or the opposing member
By changing the height of the protrusion provided on one side,
The amount can be adjusted. [0051]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a first reference example related to the present invention . FIG. 2 is a cross-sectional view showing a state in which the diaphragm is bent. FIG. 3 is a sectional view of a second reference example related to the present invention . FIG. 4 is a sectional view of a third reference example related to the present invention. FIG. 5 is a plan view of the same pressure sensor chip. FIG. 6 is a sectional view of a fourth reference example related to the present invention. FIG. 7 is a sectional view of a fifth reference example related to the present invention. FIG. 8 is a sectional view of a sixth reference example related to the present invention . FIG. 9 is an explanatory view showing a procedure when the projection is provided by a stud bump method. FIG. 10 is a cross-sectional view of one embodiment of the present invention. FIG. 11 is a cross-sectional view showing a state in which the diaphragm is bent. FIG. 12 is a sectional view of a conventional example. [Description of Signs] 1 Substrate 1a Opposing surface 1c Diaphragm 1f Opposite surface 1g Opposing space 1h Projection 2 Joining member 2a Communication hole 2b Depression 2d Projection 4 Opposing member 4a Communication hole 4b Projection 5 Package 5c Communication hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-155971 (JP, A) JP-A-7-159432 (JP, A) JP-A-8-178776 (JP, A) JP-A 64-64 61641 (JP, A) JP-A-6-88762 (JP, A) JP-A-3-19940 (JP, U) JP-A-4-12436 (JP, Y2) JP-A-4-506257 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G01L 9/04

Claims (1)

(57) [Claims 1] A silicon substrate provided with a plate-shaped diaphragm by locally forming a thin film, an opposing member arranged opposite to the diaphragm, and an opposing member to be joined. A package for accommodating the substrate together with the member, wherein the pressure sensor detects a pressure change by the amount of deflection of the diaphragm by receiving a pressure from a surface opposite to the surface facing the facing member, wherein the facing member or the package At least one of
Said diaphragm communicating hole communicating with the opposing space between are provided to penetrate from the outside face, said the opposing member, <br/> its diaphragm by the diaphragm excessive pressure is transmitted to flex A pressure sensor provided with a protrusion capable of contacting the pressure sensor.