JPH09126920A - Semiconductor pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor pressure sensor with a relatively small packaging space. SOLUTION: In a sensor body 1, a glass pedestal 25 is joined to a sensor chip 20 where a strain gauge 22 is formed on a diaphragm 24. Then, a bump 29 which is electrically connected to the strain gauge 22 protrudes from one surface of the sensor chip 20 where the strain gauge 22 is formed. The bump 29 is packaged on a circuit pattern 32 being formed on a circuit substrate 30 by face-down bonding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small semiconductor pressure sensor utilizing the piezoresistive effect, and more particularly to a vehicle-mounted semiconductor pressure sensor suitable for engine control, transmission control, suspension control, brake control and the like. .

[0002]

2. Description of the Related Art Many semiconductor pressure sensors conventionally provided have a shape in which a terminal pin or a lead piece projects from a package or a shape in which a lead wire is pulled out from the package. For example, there are provided a TO-5 type package in which the terminal pins are projected from the lower surface, and a DIP-shaped package in which the lead pieces 11 are projected on both side surfaces of the package 10 as shown in FIG. .

The semiconductor pressure sensor shown in FIG. 12 has a package 10 made of synthetic resin which is molded integrally with a lead frame 12, and portions of the lead frame 12 protruding from both side surfaces of the package 10 are lead pieces 11. Used as. A recess 13 having an open bottom surface is formed on the package 10, and a chip storage recess 14 is formed on the inner bottom surface of the recess 13. A cylindrical introducing cylinder 15 is projected on the upper surface of the package 10, and a pressure introducing hole 16 for communicating the inside and outside of the package 10 is formed in a portion extending from the introducing cylinder 15 to the chip accommodating recess 14.

A part of the lead frame 12 is the package 1
It functions as a bonding pad exposed on the inner bottom surface of the recess 13 at 0 and connected to a sensor chip 20 described later through a bonding wire 21 made of gold or aluminum. Further, a step portion 18 is formed near the opening of the recess 13, and the recess 13 of the package 10 is closed by a cover plate 19 whose peripheral portion abuts on the step 18. The lid plate 19 is hermetically sealed to the package 10 using an adhesive.

By the way, as the sensor chip 20, a plurality of (generally four for forming a bridge circuit) strain gauges 22 formed on a silicon single crystal semiconductor substrate 23 is used. Each strain gauge 22 is formed by diffusing impurities in the semiconductor substrate 23 and converts a change in stress into a change in electric resistance. Further, the strain gauge 22 is formed at a portion of the diaphragm 24 which is formed thinner in the semiconductor substrate 23 than other portions, and the diaphragm 2
When 4 is bent due to the pressure difference between the front and back sides, the strain gauge 22 converts a change in stress associated with the change into a change in electrical resistance, thereby converting a change in pressure into a change in electrical resistance.

The sensor chip 20 formed as described above
Is bonded to the pedestal 25 of insulating material by using a bonding method such as an anodic bonding method to form the sensor body 1.
The pedestal 25 of the sensor body 1 is airtightly fixed to the bottom surface of the chip accommodating recess 14 using an adhesive. The pedestal 25 is formed with pressure introducing holes 26 penetrating to the front and back, and the pressure introducing holes 26 communicate with the pressure introducing holes 16 formed in the package 10. Therefore, the pressure outside the package 10 acts on the upper surface of the diaphragm 24 formed on the sensor chip 20. On the other hand, the pedestal 25 is airtightly fixed to the package 10, and the lid plate 19 is attached to the package 10.
Package 1 is hermetically sealed to
Since an airtight pressure reference chamber 27 is formed inside 0,
A substantially constant pressure inside the pressure reference chamber 27 acts on the lower surface of the diaphragm 24. Therefore, when the pressure outside the package 10 changes, a pressure difference occurs between the front and back of the diaphragm 24, and as a result, the change in external pressure can be detected.

By the way, the sensor chip 20 is connected to the lead frame 12 via the bonding wire 21 as described above.
And is connected to an external circuit via the lead piece 11 which is a part of the lead frame 12. The lead piece 11 is bent in the thickness direction of the package 10 (upward or downward), and the circuit pattern 32 is made of a thin conductive material.
An external circuit is formed by being inserted into a socket 31 mounted on a circuit board (for example, a board forming a hybrid integrated circuit) 30 on which a thin plate is attached, a thin film is attached, a conductive paste is applied, or the like. Connected. Here, the lead frame 12 is formed using a band plate material (hoop material), and each lead piece 11 is separated by cutting the tie bar after the package 10 is molded. Therefore, the lead piece 11 is packaged after the tie bar is cut. Bend in the thickness direction of 10.

[0008]

As described above, in the conventional semiconductor pressure sensor, the bonding wire 21 is used to connect the sensor chip 20 to the lead piece 11, and the lead piece 11 of the package 10 is used. Since it projects on both side surfaces, there arises a problem that the mounting area and mounting volume increase. That is, in order to connect the lead frame 12 and the sensor chip 20 via the bonding wire 21, the lead frame 12 is connected to the sensor chip 2.
Since the lead frames 12 are arranged side by side on the side of 0 and the lead frame 12 projects laterally from the package 10, the mounting area is significantly increased as compared with the width of the sensor chip 20. Furthermore, when the socket 31 is used as described above, the socket 31 has to be mounted on the circuit board 30 in advance, which requires a lot of time and effort for mounting work and leads to an increase in cost due to an increase in the number of parts. In addition, the presence of the socket 31 further increases the mounting area and increases the height from the circuit board 30, resulting in a large mounting volume.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a semiconductor pressure sensor which has a relatively small mounting space and can be mounted at low cost without using a socket. It is in.

[0010]

In order to achieve the above object, the invention of claim 1 has a diaphragm which is formed thinner than other parts and which bends under pressure. The sensor body is mounted on the surface together with the plate-shaped sensor body in which the convex electrodes that are electrically connected to each other protrude on one surface, and the circuit pattern of the thin conductive material is formed on the surface of the base material and the electronic components that form the peripheral circuits. A circuit board is provided, and electrode pads arranged so as to match the array of the convex electrodes of the sensor body are formed on the circuit pattern, and the convex electrodes are joined to the electrode pads by face down bonding. It is characterized by

According to this structure, the alignment between the sensor body and the electrode pad becomes easier as compared with the case where the sensor body is joined to the terminal pin. In particular, when the convex electrodes are mounted by solder, the sensor body does not move out of position and fall from the terminal pins when the solder melts, unlike when mounting the sensor body on the terminal pins. The main body is automatically positioned (self-alignment) and mounted at a desired position according to the position of the electrode pad. Moreover, since it can be surface-mounted on the circuit board together with the electronic components forming the peripheral circuit, workability and productivity are improved. Further, as compared with the case where the terminal pins are used, the dimension of protrusion from the circuit board at the time of mounting is small and the pressure sensor as a whole including the peripheral circuit can be downsized. Furthermore, the distance between the electronic components that form the peripheral circuit and the sensor body is reduced, and it is less susceptible to noise, so the sensitivity can be improved. Further, since the convex electrodes are used for mounting on the circuit board and the contact area with the circuit board is relatively small, and the convex electrodes can be deformed to some extent, the difference in the coefficient of thermal expansion between the sensor body and the circuit board is large. It is possible to obtain a semiconductor pressure sensor that can alleviate the thermal stress due to (3) and have excellent temperature characteristics (the offset temperature characteristics are stable and the hysteresis with respect to temperature is small).

According to a second aspect of the present invention, in the sensor body according to the first aspect, the sensor chip has a bottom wall of the recess as a diaphragm by opening the recess at the center of one surface of the semiconductor substrate in the thickness direction. And a pedestal airtightly joined to the one surface of the sensor chip so as to form a space between the recess and the recess. According to this configuration, by forming a space between the sensor chip and the pedestal, it is possible to detect the absolute pressure when the space is evacuated, and the pressure to be measured is introduced into this space to make the sensor main body. It is also possible to detect the relative pressure with respect to the ambient pressure.

According to a third aspect of the present invention, in the second aspect of the present invention, the convex electrode is provided on the other surface of the sensor chip so that at least the strain gauge and the convex electrode of the sensor body are connected to the circuit board. A second case is provided, which is fixed to the circuit board so as to surround the second case, and a part of the peripheral wall of the case is bent under pressure.
Is provided, and the space surrounded by the case and the circuit board is filled with an inert liquid that transmits the pressure change received by the second diaphragm to the diaphragm of the sensor main body and protects the strain gauge and the convex electrode from corrosion. It is characterized by

According to this structure, since the strain gauge and the convex electrode are immersed in the inert liquid, the strain gauge and the convex electrode do not come into contact with air, corrosion is prevented, and durability is improved. . The invention of claim 4 is characterized in that, in the invention of claim 2, a case fixed to the circuit board is provided so as to surround the sensor main body with the circuit board.

According to this structure, since the sensor main body is surrounded by the circuit board and the case, a package for accommodating the entire circumference of the sensor main body is unnecessary, and the package cost can be reduced. In the invention of claim 5,
In the invention of claim 4, the pedestal provided on the sensor body is fixed to the inner peripheral surface of the case.

According to this structure, since the sensor body is fixed to the case and the case is fixed to the circuit board, the fixing strength of the sensor body is higher than that when the sensor body is bonded to the circuit board only by the convex electrodes. Can be improved. Further, if elastic materials are used for the fixing parts of the sensor body and the case and the case and the circuit board, the stress acting on the convex electrodes can be dispersed and relaxed at the fixing parts, and the contact state of the convex electrodes can be stabilized. Can be kept. Further, by appropriately setting the height dimension of the case from the circuit board, it is possible to stabilize the connection state of the convex electrode to the circuit board by pressing the sensor body against the circuit board side by the case.

According to a sixth aspect of the present invention, in the second aspect of the present invention, the sensor chip is formed of a first conductivity type semiconductor, and the sensor chip is provided with a high concentration second type semiconductor in a peripheral portion of the diaphragm. Second conductive path is formed on the pedestal, and the pedestal is electrically connected to the first conductive path by applying metallization to the inner circumference of the through hole penetrating the portion corresponding to the first conductive path. A conductive path is formed, and a strain gauge provided on the sensor chip and a convex electrode protruding from one surface of the pedestal are electrically connected via a first conductive path and a second conductive path. To do.

In this structure, since the convex electrode is provided on the surface of the sensor body opposite to the surface on which the strain gauge is provided, the stress from the convex electrode to the sensor body hardly acts on the diaphragm. It enables stable and highly accurate pressure measurement. Further, since the strain gauge is exposed on the surface of the sensor body opposite to the surface facing the circuit board, the probe for conductivity inspection is brought into contact with the strain gauge side so that the convex electrodes and the circuit board are mounted after mounting the sensor body. It is also possible to inspect the connection state with and to further adjust the characteristics of the strain gauge after mounting the sensor body by trimming the strain gauge with laser light or the like.

According to a seventh aspect of the present invention, there is provided a plate having a diaphragm which is formed thinner than other portions and which is bent by receiving pressure so that a convex electrode electrically connected to a strain gauge on the diaphragm is projected on one surface. -Shaped sensor body, a circuit board on which a circuit pattern made of a thin conductive material is formed on the surface of a base material that is thicker than the sensor body, and electronic components that form peripheral circuits are mounted, and a circuit board that penetrates in the thickness direction of the circuit board. The first lid plate fixed to the circuit board so as to close one opening surface of the housing hole with the sensor main body housed in the provided housing hole fixed to one surface, and the other opening surface of the housing hole. The second cover plate is fixed to the circuit board so as to be closed, and a part of the circuit pattern is arranged so as to extend into the opening of the housing hole and match the array of the convex electrodes of the sensor body. Forming a lead piece It is convex electrode against, characterized in that it is joined from the inside of the receiving hole.

According to this structure, since the sensor body is mounted within the thickness of the circuit board, the mounting space of the sensor body can be significantly reduced. Further, since the sensor body is fixed to one of the lid plates that closes the storage hole, if a material having a coefficient of thermal expansion close to that of the sensor body is selected as the material forming the lid plate, the thermal stress on the sensor body is reduced. This enables stable pressure measurement. Further, since the lead piece is provided so as to project inside the accommodation hole, the stress acting on the convex electrode due to the elasticity of the lead piece can be relieved. In addition, by covering the storage hole with the cover plate, it is possible to mount circuit components on the cover plate as needed, and the mounting efficiency including the peripheral circuits is increased.

According to the invention of claim 8, in the invention of claim 7, at least a part of the gap formed between the inner peripheral surface of the housing hole and the outer peripheral surface of the sensor body is filled with a gel-like stress relaxation material. It is characterized by being. According to this configuration,
By filling the periphery of the sensor body with a gel-like stress relaxation material, it is possible to reduce vibrations and impacts on the sensor body.

According to a ninth aspect of the invention, in the first aspect of the invention, the sensor body is a sensor chip in which a cavity is provided inside a semiconductor substrate to form a diaphragm on a part of a peripheral wall of the cavity. . With this configuration, it is not necessary to join the pedestal to the sensor chip, and the material cost can be reduced.

According to a tenth aspect of the present invention, in the first aspect of the present invention, the sensor body is a sensor chip in which the bottom wall of the recess is a diaphragm by opening the recess in the center of one surface of the semiconductor substrate in the thickness direction. There is a conductive path that penetrates in the thickness direction of the sensor body around the diaphragm of the sensor chip, and a convex shape electrically connected to the strain gauge through the conductive path is formed on the one surface of the sensor chip. Electrodes are projected, and a stress relaxation material is filled between the peripheral part of the sensor chip and the circuit board to hermetically seal the space between the recess and the circuit board and to relieve the stress of the convex electrodes. It is characterized by being.

According to this structure, the same structure and operation as those of the sixth aspect of the invention are provided, and in addition, the stress relief material is filled between the peripheral portion of the sensor chip and the circuit board to form the recess. Since the airtight space is formed with the circuit board, it is not necessary to join the pedestal to the sensor chip, and the material cost can be reduced. Moreover, the stress relaxation material supports the convex electrode to increase the fixing strength of the sensor chip to the circuit board, and relaxes the stress acting on the sensor chip to enable stable and accurate pressure measurement.

According to an eleventh aspect of the present invention, in the first aspect of the present invention, the sensor body is a sensor chip in which the bottom wall of the recess is a diaphragm by opening the recess in the center of one surface of the semiconductor substrate in the thickness direction. Then, a conductive path penetrating in the thickness direction of the sensor body is formed in the peripheral portion of the sensor chip surrounding the diaphragm, and a convex portion electrically connected to the strain gauge through the conductive path is formed on the one surface of the sensor chip. Shaped electrodes are provided in a protruding manner, and the sensor chip is fixed with a cover plate having a thickness smaller than the protruding size of the convex electrodes from the sensor chip and hermetically sealing the recess.

In this structure, the same structure and operation as those of the sixth aspect are provided, and in addition, since the cover plate is provided within the projecting size of the convex electrode, the thickness size of the sensor main body is compared with the case where the pedestal is provided. Can be made smaller. Moreover, even if the convex electrode is deformed during mounting, the protruding dimension of the convex electrode from the sensor body does not become smaller than the thickness of the cover plate, so the contact area of the convex electrode with the circuit board is small. Therefore, the effect of stress relaxation due to the convex electrode can be maintained.

According to a twelfth aspect of the invention, in the tenth or eleventh aspect of the invention, the sensor chip is formed of a first conductivity type semiconductor, and the conductive path is formed of a high concentration second conductivity type semiconductor. Is characterized by. With this configuration, the conductive path can be formed by a semiconductor manufacturing process, and thus the manufacturing is easy.

According to a thirteenth aspect of the invention, in the tenth aspect or the eleventh aspect of the invention, the conductive path is provided with metallization on the inner peripheral surface of the through hole penetrating the semiconductor substrate forming the sensor chip via an insulating layer. It is characterized in that it is formed by applying. In this structure, compared with the structure of the twelfth aspect of the invention, the current leakage can be reduced by the insulating layer, and the conductivity of the conductive path can be increased by the metallized metal. As a result, the sensitivity of pressure measurement is increased and the measurement accuracy is improved.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 is a sectional view of this embodiment. The sensor chip 20 has the same structure as that described in the related art, and the sensor body 1 is formed by being bonded to a pedestal 25 made of heat-resistant glass (trade name: Pyrex) by an anodic bonding method. Here, in the anodic bonding method, a pedestal 25 of heat-resistant glass having a thermal expansion coefficient similar to that of the sensor chip 20 made of silicon single crystal is used, and smooth surfaces of the opening side of the recess of the sensor chip 20 and the pedestal 25 are And a method of applying a negative voltage of about 500 V to the pedestal 25 in a state of being heated to 300 to 400 ° C. and applying a large Coulomb force to the interface between the sensor chip 20 and the pedestal 25. Chip 20
This is a method of joining the sensor chip 20 and the pedestal 25 by causing a chemical bond at the interface between the pedestal 25 and the pedestal 25.

In the state where the sensor chip 20 and the pedestal 25 are joined, an airtight pressure reference chamber 27 is formed between the sensor chip 20 and the pedestal 25. That is, the sensor chip 20 has a recess opening in the center of one surface and the bottom wall of the recess serves as the diaphragm 24. By closing the recess with the pedestal 25, the interior of the recess becomes the pressure reference chamber 27. . By the way, since the sensor chip 20 and the pedestal 25 are heated at the time of joining, the internal pressure of the pressure reference chamber 27 becomes about 0.4 to 0.5 at room temperature when they are joined under atmospheric pressure. On the other hand, in order to measure the absolute pressure, the pressure reference chamber 27 needs to be evacuated, and the sensor chip 20 and the pedestal 25 must be joined in vacuum. in this case,
Since there is no heat conduction in a vacuum, the heater is arranged so as to surround the sensor chip 20 and the pedestal 25 so that the radiant heat is mainly used for heating.

The upper surface of the sensor chip 20, which is the opening side of the recess, is bonded to the pedestal 25 as described above, and the sensor chip 2
Wiring pattern 2 for connecting to the external circuit on the bottom surface of 0
8 are formed. A bump 29 as a convex electrode is fixed to the wiring pattern 28, and the bump 29 is joined to the circuit pattern 32 on the circuit board 30 by face-down bonding. The bumps 29 are solder, gold,
It is formed using various metals such as tin and copper and conductive synthetic resins.

In this embodiment, the bumps 29 are formed using solder. Since the wiring pattern 28 of the sensor chip 20 is made of aluminum and has low solder wettability, an intermediate layer of a metal film is formed on the surface of the wiring pattern 28 in order to improve the solder wettability. The intermediate layer basically consists of two layers of metal film, and the layer on the side of the wiring pattern 28 is made of chromium, which has a high bonding strength with aluminum, and the bump 2
Copper having a high bonding strength with solder is used for the layer on the 9 side. Also,
The intermediate layer is formed by a method such as sputtering or vapor deposition. The solder material used for the bumps 29 is, for example, one having a tin: lead ratio of 60:40 or 5:95.
The metal film serving as an intermediate layer is deposited on the wiring pattern 28 by a method such as vapor deposition using a metal mask or plating using a photoresist mask. After that, reflow is performed in an atmosphere of an inert gas (rare gas or nitrogen gas), and it is melted into a hemispherical shape due to surface tension.

When gold is used to form the bump 29, a ball having a diameter of 50 to 200 μm is formed at the tip of a thin wire similar to the bonding wire, and this ball is mounted on a capillary and ultrasonic waves are applied. The ball is bonded to the wiring pattern 28 of the sensor chip 20 by applying, and then only the ball is separated from the wire by laterally shifting the capillary. When the bumps 29 are formed using a conductive synthetic resin, a conductive paste (silver paste or copper paste) is used as the conductive synthetic resin, and the surface of the wiring pattern 28 is applied in a hemispherical shape and then heated. Go and cure. As described above, the bumps 29 can be formed of tin or copper, but various known methods can be applied to the method of forming the bumps 29, and thus the description thereof will be omitted.

The bump 29 formed as described above
If it is formed of solder, it can be bonded to the circuit pattern 32 of the circuit board 30 by a reflow furnace together with the mounting of electronic components constituting the peripheral circuit.
The bump 29 can be connected to the circuit pattern 32 on the circuit board 30 by using a conductive adhesive (conductive paste such as silver paste or copper paste), indium alloy, or solder depending on the material. When a conductive adhesive is used, the conductive adhesive is cured by heating at 100 to 200 ° C. after bonding.

A case 40 is fitted on the sensor body 1 with the sensor body 1 bonded to the circuit board 30. The case 40 is made of metal (Kovar, nickel, nickel silver, iron, etc.) in a bottomed tubular shape with one surface open, and the opening edge of the case 40 is soldered, welded, or bonded with a thermosetting synthetic resin. The circuit board 30 is sealed to the circuit board 30.
A space for accommodating the sensor chip 20 is formed between and.
In the case of soldering or welding, a pattern is formed on the circuit board 30 over substantially the entire circumference of the portion in contact with the case 40. However, this pattern is insulated from the circuit pattern 32, and the case 40 is also insulated from the circuit pattern 32.

A thin diaphragm 41 made of stainless steel or the like is integrally provided at the center of the bottom wall (upper wall in FIG. 1) of the case 40. Therefore, an airtight space is formed between the case 40 and the circuit board 30, and the sensor chip 20 and the pedestal 25 are housed in this airtight space. An airtight space formed between the circuit board 30 and the case 40 is filled with an inert liquid 42 made of silicone oil and having an insulating property. The inert liquid 42 is applied to the circuit board 30.
Alternatively, it is introduced into the airtight space from an introduction hole formed in a part of the case (portion excluding the diaphragm 41) 40, and the introduction hole is sealed by soldering or welding after filling the inert liquid 42.

With the above-described structure, the sensor chip 20 is immersed in the inert liquid 42 and shielded from the outside air, so that the deterioration is reduced and stable electrical and mechanical characteristics can be maintained for a long period of time. it can. On the other hand, the pressure acting on the diaphragm 41 from the outside of the case 40 is transmitted to the diaphragm 24 of the sensor chip 20 via the inert liquid 42. The pressure sensor having the above structure is called a double diaphragm system because it has two diaphragms 24 and 41.

As described above, the sensor chip 2 is used in this embodiment without using the lead frame unlike the conventional structure.
Circuit pattern 3 of the circuit board 30
Since it is directly attached by face down bonding to No. 2, a socket is not required for connection with an external circuit, and the width of the case 40 is significantly smaller than that of the case where a lead frame is used, and the width of the sensor chip 20 is about the same. It becomes possible to miniaturize. That is, the mounting area and the mounting height are reduced. In addition, it is small and inert liquid 4
Since the filling amount of 2 is small, it is relatively lightweight despite the use of the double diaphragm system, and the change in internal pressure due to the thermal expansion of the inert liquid 42 is small. Further, although the circuit board 30 or the circuit pattern 32 and the sensor chip 20 have different coefficients of thermal expansion, the circuit pattern 32 and the sensor chip 20 have the bumps 2
9 and the contact surfaces of the circuit pattern 32 and the bump 29 and the sensor chip 20 and the bump 29 are very small, about 50 to 200 μm.
The strain due to the difference in the coefficient of thermal expansion is hard to be transmitted, and in this respect also, the influence of the ambient temperature on the sensor chip 20 is small.

(Embodiment 2) In Embodiment 1, since the pressure sensor is mounted by face-down bonding on the circuit board 30 on which the electronic components forming the peripheral circuit are mounted, the distance between the electronic component and the pressure sensor is compared. It becomes close to the target, the electric path can be shortened to reduce noise, and the temperature difference between the electronic component and the pressure sensor can be reduced to facilitate temperature compensation. In the present embodiment, the temperature difference between the electronic component and the pressure sensor is further reduced as compared with the first embodiment, and as shown in FIG. The space surrounded by the case 40 and the circuit board 30 is filled with the inert liquid 42. Also, the case 40
A diaphragm 41 is provided on a part of the
The pressure acting on the sensor body 1 passes through the inert liquid 42.
Of the diaphragm 24. That is, this embodiment also employs the double diaphragm system.

In this structure, the electronic parts 2 constituting the peripheral circuit and the sensor body 1 are housed in one case 40,
Moreover, since the case 40 is filled with the inert liquid 42, heat is conducted through the inert liquid 42 more quickly than in the air, and as a result, the temperature difference between the electronic component 2 and the sensor body 1 is reduced. Get smaller. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3) In the present embodiment, the entire sensor chip 20 and the pedestal 25 are not immersed in the inert liquid 42, but as shown in FIG. By immersing only the peripheral portion of 29 in the inert liquid 42, the corrosion of the electric circuit portion is prevented.

The basic structure is the same as that of the first embodiment,
The pressure reference chamber 27 is formed between the sensor chip 20 and the pedestal 25 by joining the pedestal 25 to the sensor chip 20, a wiring pattern (not shown) is formed on the lower surface side of the sensor chip 20, and the wiring pattern is formed. Bumps 29 are projected on the. The bump 29 is joined to the circuit pattern 32 of the circuit board 30 by face down bonding. The case 40 has a tubular shape with both ends open, and the height from the circuit board 30 when the sensor chip 20 is mounted on the circuit board 30 is set to the same level as the sensor chip 20. In addition, the upper end of the case 40 and the sensor chip 2
A space between 0 and the pedestal 25 is sealed by a seal 45. Silicone resin or low melting point glass is used for the seal 45. A diaphragm 41 is formed on a part of the peripheral wall of the case 40, and is surrounded by the case 40, the circuit board 30, and the seal 45 in order to transmit the pressure acting on the diaphragm 41 to the diaphragm 24 of the sensor chip 20. The airtight space is filled with the inert liquid 42. That is, this embodiment also employs the double diaphragm system. With this inert liquid 42, the sensor chip 2
The strain gauge 22, the wiring pattern 28, and the bumps 29 formed at 0 are not exposed to the air, and corrosion of these due to oxidation can be prevented.

(Fourth Embodiment) In the first embodiment, the case 40 is used.
However, as shown in FIG. 4, instead of the case 40, a silicone rubber seal 46 that hermetically seals between the peripheral portion of the sensor chip 20 and the circuit board 30 may be provided. In this case, since the case 40 provided with the diaphragm 41 that receives the pressure to be detected does not exist, the circuit board 3
A through hole 38 is formed in a part of 0, and a diaphragm 41 is provided so as to close the through hole 38. Since the inert liquid 42 is filled in the airtight space surrounded by the sensor chip 20, the circuit board 30, and the seal 46, and the through hole 38 is formed so as to communicate with this airtight space, the pressure acting on the diaphragm 41 is increased. Are transmitted to the diaphragm 24 of the sensor chip 20 via the inert liquid 42. That is, the configuration of this embodiment is also a double diaphragm system. Other configurations and operations are the same as those in the first embodiment, and in this embodiment as well as in the third embodiment, it is possible to prevent the corrosion of the conductive paths of the sensor chip 20 while minimizing the amount of the inert liquid 42. .

(Embodiment 5) In this embodiment, as shown in FIG. 5, the diaphragm 2 formed on the sensor chip 20.
A fluid, which is a pressure detection target, is introduced into a space between the base 4 and the pedestal 25, and the space surrounded by the circuit board 30 and the case 40 serves as a pressure reference chamber 27. That is, the sensor chip 20 has the same configuration as that of the first embodiment, and is bonded to the pedestal 25 made of heat-resistant glass by the anodic bonding method. Bumps 29 are formed on the sensor chip 20, and the bumps 29 are bonded to the circuit patterns 32 formed on the circuit board 30. Further, as in the first embodiment, the bottomed cylindrical case 40
Is sealed to the circuit board 30 so as to cover the sensor chip 20 and the pedestal 25.

By the way, in this embodiment, the sensor chip 2
In order to introduce a fluid whose pressure is to be detected into the space between the zero diaphragm 24 and the pedestal 25, the pedestal 25 is formed with pressure introducing holes 26 penetrating the front and back in the thickness direction using an ultrasonic drill or the like. To be done. Further, the pedestal 25 is airtightly adhered to the inner bottom surface of the case 40 by using silicone resin or the like except for the portion of the pressure introducing hole 26. Therefore, the transmission of the external force from the case 40 to the sensor body 1 is relieved by the adhesive portion. Further, by appropriately setting the height dimension of the case 40, the bump 29 can be pressed against the circuit pattern 32 by fitting the case 40 on the sensor body 1 and fixing the case 40 to the circuit board 30.
As a result, the reliability of the electrical connection of the bump 29 can be improved. In the case 40, the introduction cylinder 15 having the pressure introduction hole 16 communicating with the pressure introduction hole 26 is projected on the upper surface. In FIG. 5, the fluid to be pressure-detected is introduced through the tube 43 connected to the introduction cylinder 15.

Since the pedestal 25 is hermetically bonded to the case 40, the sensor chip 20 and the pedestal 25 are attached.
The space surrounded by the circuit board 30 and the case 40 is separated from the pressure introducing holes 16 and 26, but a vent hole 44 is formed in a part of the bottom wall (upper wall in FIG. 5) of the case 40. As a result, the inside of the pressure reference chamber 27 is maintained at approximately atmospheric pressure. However, the airtightness may be maintained without forming the ventilation hole 44, and an appropriate gas such as air, nitrogen, or a rare gas (mainly argon) may be sealed in the pressure reference chamber 27 at a desired pressure.

The circuit board 30 includes a thick film ceramic, a silicon wafer, a polyimide resin / epoxy resin / polyphenylene sulfide resin (PPS) / liquid crystal polymer (LC).
A synthetic resin such as P), glass, a metal such as copper, Kovar, and aluminum can be used. However, when metal is used for the circuit board 30, insulation is necessary between the circuit board 32 and the circuit pattern 32. Therefore, glass epoxy or the like is applied as an insulating layer on the surface of the metal. Further, the board material of these circuit boards 30 is not particularly limited, and only generally available materials are listed. These board materials can also be used for the circuit board 30 in the embodiments described below.

Other structures and effects are the same as those of the first embodiment. Since the bumps 29 provided on the sensor chip 20 are joined to the circuit pattern 32 of the circuit board 30 by face down bonding, a lead frame is used. The size is small and the mounting space is smaller than the conventional configuration. (Embodiment 6) In the present embodiment, as shown in FIG. 6, the diaphragm 24 and the sensor chip 20 of the sensor chip 20.
A pressure reference chamber 27 is provided between the pedestal 25 and the pedestal 25. That is, the sensor chip 20 and the pedestal 25 have the same configuration as that of the first embodiment.

On the other hand, the container for accommodating the sensor chip 20 and the pedestal 25 is formed by the circuit board 30 and a pair of cover plates 33, 34 attached to both surfaces in the thickness direction of the circuit board 30. That is, the sensor chip 2 is mounted on the circuit board 30.
The thickness of the circuit board 30 is larger than the total thickness of 0 and the pedestal 25, and a part of the circuit board 30 has a storage hole 35 penetrating in the thickness direction. Also, the circuit board 30
The conductor forming the circuit pattern 32 on one surface is thick enough to form the lead piece 17 described later. The lid plates 33 and 34 described above cover the circuit board 30 by closing the storage hole 35.
It is fixed in an airtight manner with an adhesive. Circuit board 3
The cover plate 33 fixed to one surface of the circuit pattern 32 on which the circuit pattern 32 is not formed is flat and
The lid plate 34 fixed to the one surface on which is formed is formed with a recess 36 having an opening that substantially coincides with the storage hole 35. An adhesive is used to fix the cover plates 33 and 34 to the circuit board 30, but soldering or welding may be performed when a metal material is used. In particular, if the cover plate 33 is made of Kovar, the difference in the coefficient of thermal expansion from the pedestal 25 is small, so that the stress due to the thermal expansion of the circuit board 30 is less likely to act on the pedestal 25, and the pressure measurement is highly accurate and stable. Can be done. Then, the circuit board 3
0 is formed in a shape in which a part of the circuit pattern 32 is projected to the inner peripheral side of the storage hole 35 along the opening surface of the storage hole 35,
The protruding portion of the circuit pattern 32 functions as the lead piece 17. That is, the sensor chip 2 is attached to the lead piece 17.
The bumps 29 protruding from 0 are joined from the inside of the storage hole 35, and the lid plate 33 that closes the storage hole 35 is fixed to the pedestal 25 joined to the sensor chip 20 with an adhesive. With this structure, the mechanical stress acting on the bumps 29 is relieved by the elasticity of the lead pieces 17, and stress is less likely to be applied to the sensor body 1. A stress relaxation material 37 made of an insulating material is filled between the outer peripheral surface of the pedestal 25 and the inner peripheral surface of the storage hole 35. A gel material such as a silicone resin is used for the stress relaxation material 37, and the stress relaxation material 37 can reduce external force such as vibration and impact. Of course, the stress relaxation material 37 does not necessarily have to be provided when used in an environment where an external force hardly acts.

After fixing the cover plate 33, the recess 36 is formed in the storage hole 35.
If the cover plate 34 is airtightly fixed to the circuit board 30 in such a manner as to match with the above, a case for housing the sensor chip 20 is formed by the circuit board 30 and the cover plates 33 and 34. That is, the sensor chip 20 and the pedestal 25 are mechanically protected. Moreover, the sensor chip 20 and the pedestal 25
Will be accommodated within the range of the thickness of the circuit board 30, and the mounting space can be significantly reduced. Here, the pressure introducing hole 16 is formed in the cover plate 34, and the pressure of the fluid introduced from the pressure introducing hole 16 acts on the diaphragm 24 of the sensor chip 20 so that the pressure can be detected. In other words, the pressure sensor having this configuration can measure the pressure by disposing the circuit board 30 in the fluid to be measured.

In the above embodiment, the lead piece 17 is formed by extending a part of the circuit pattern 32, but a separately provided conductive small piece (beam lead) is formed on the circuit pattern 32 around the storage hole 35. It is also possible to connect the lead piece 1 by connecting it or connecting a thin metallized polyimide film (TAB film) to the circuit pattern 32.
7 can be formed. In this case, the circuit pattern 32 need not be thick enough to form the lead piece 17, and may be thin. Although the pedestal 25 is adhered to the lid plate 33 with an adhesive, the pedestal 25 is omitted and the lid plate 33 is made of a glass material, so that the sensor chip 20 is joined to the pedestal 25 by the anodic bonding method. Good. Other configurations and effects are similar to those of the first embodiment.

(Embodiment 7) In each of the above embodiments, the sensor chip 20 is joined to the pedestal 25, but in this embodiment, as shown in FIG. 7, a cavity 51 is formed inside the sensor chip 20. As a result, the structure in which the upper portion of the cavity 51 functions as the diaphragm 24 is adopted.

More specifically, the central portion of the upper surface of the semiconductor substrate 23 made of n-type single crystal silicon is nitrided into a square shape to form a silicon nitride film (Si ₃ N ₄ ).
An etching hole 52 is formed in an appropriate place around the silicon nitride film, and an etching solution is introduced from the etching hole 52 to perform anisotropic etching, thereby forming an inverted pyramidal cavity 51 on the back surface side of the silicon nitride film. Of. With this structure, the silicon nitride film on the upper surface side of the cavity 51 can be used as the diaphragm 24. After the cavity 51 is formed, the etching solution is washed to remove the cavity 51.
Is exhausted and a film is formed by plasma CVD to seal the etching hole 52. That is, the cavity 51 forms the vacuum pressure reference chamber 27. The strain gauge 2 is formed on the upper surface of the diaphragm 24 formed as described above.
2 is formed, and the strain gauge 22 is connected to a wiring pattern 28 made of an aluminum thin film.

By the way, the circuit pattern 3 of the circuit board 30
The bump 29 connected to 2 is provided on the lower surface side of the sensor chip 20 so as to project. On the other hand, since the wiring pattern 28 is formed on the upper surface of the semiconductor substrate 23 as described above, in order to electrically connect the wiring pattern 28 and the bump 29, the conductive path 53 is provided inside the semiconductor substrate 23 in this embodiment. Is formed. That is, the conductive path 53 is formed of a p ^{+ type} semiconductor, and the conductive path 53 is formed by the thermomigration method. That is, aluminum is vapor-deposited on the upper surface of the n-type semiconductor substrate 23, and the semiconductor substrate 23 is heated to about 1000 ° C.
A temperature gradient of about 50 ° C./cm is applied so that the lower surface of the sample 3 has a higher temperature than the upper surface thereof. If you heat in this way,
Aluminum melts and advances to the lower surface while melting silicon in the semiconductor substrate 23, and p ⁺ containing aluminum is added.
That is, the conductive semiconductor is recrystallized to form the conductive path 53. The surface of the p ^{+ type} semiconductor exposed on the back surface of the semiconductor substrate 23 is metallized to form a metal thin film such as copper, and the bumps 29 are formed on the surface of this metal thin film.

After forming the bumps 29, the circuit board 3
The circuit pattern 32 of 0 is joined by face down bonding. That is, the circuit pattern 30 is assembled on the circuit board 30 together with other parts, and the circuit pattern 32
Connect to In this configuration, the circuit board 3 is in a bare chip state.
Since it is mounted at 0, the mounting space can be made very small. In addition, the circuit board 30 of the sensor body 1
Since the wiring pattern 28 is exposed on the surface (upper surface in the figure) opposite to the surface opposite to the surface of the sensor main body 1, the probe for conductivity inspection is brought into contact with the wiring pattern 28 and the circuit pattern 32. The connection state to the circuit pattern 32 can be easily inspected. Furthermore, strain gauge 2
Since 2 is exposed on the upper surface, it is possible to adjust the operation characteristics by performing laser trimming or the like. Such easiness of inspection and easiness of adjusting operation characteristics are also realized in the following embodiments. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 8) As shown in FIG. 8, this embodiment uses a sensor chip 20 having a thin diaphragm 24 formed in the central portion, as in the sensor chip 20 shown in the first embodiment. . However, the pedestal 25 is not provided, and the thickened portion of the peripheral portion of the sensor chip 20 is used in the seventh embodiment.
It has a conductive path 53 formed by a method similar to. That is, the strain gauge 22 is formed on the upper surface of the diaphragm 24, and the wiring pattern 28 made of aluminum is formed on the upper surface of the sensor chip 20. Further, the bump 29 is formed on the lower surface of the thick portion of the sensor chip 20, and the p ^{+ type} conductive path 5 is provided between the wiring pattern 28 and the bump 29.
It conducts at 3.

The bare-chip pressure sensor formed as described above is mounted on the circuit board 30 together with other components by bonding the bumps 29 to the circuit pattern 32 of the circuit board 30 by the face-down bonding method. Here, since the presence of the bump 29 forms a gap between the circuit board 30 and the sensor chip 20, the gap is filled with the stress relaxation material 54 of synthetic resin. For example, if a liquid silicone resin or epoxy resin is applied to the vicinity of the gap using a dispenser or the like, it penetrates into the gap due to surface tension, and if it is subsequently heat-cured, an elastic stress relaxation material 54 is formed. can do. As the synthetic resin forming the stress relieving material 54, a photo-curing type (ultraviolet curing type, visible light curing type) synthetic resin can be used as well as a heat curing type. Stress relaxation material 5
4 is formed over the entire circumference of the sensor chip 20, and an airtight pressure reference chamber 27 sealed by a stress relaxation material 54 is formed between the lower surface side of the sensor chip 20 and the circuit board 30. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 9) In this embodiment, as shown in FIG. 9, the sensor chip 20 is joined to the pedestal 25 as in Embodiment 1. That is, the pressure reference chamber 27 is formed between the sensor chip 20 and the pedestal 25. Similar to the eighth embodiment, the sensor chip 20 has a thin diaphragm 24 formed in the central portion thereof and a p ^{+ -type} semiconductor conductive path 53 formed in the thick portion of the peripheral portion. Where bump 29
Since it is formed on the lower surface of the pedestal 25, it is necessary to form a conductive path 55 inside the pedestal 25 in order to electrically connect the conductive path 53 and the bump 29. So pedestal 2
5, a through hole 56 is formed, and metallization is applied to the inner peripheral surface of the through hole 56 and the surface of the conductive path 53 exposed on the lower surface of the sensor chip 20.
To form Of course, the through hole 56 formed in the pedestal 25 is aligned with the conductive path 53 formed in the sensor chip 20.

The through holes 56 are formed by performing electric discharge machining or laser machining. The electrical discharge machining adopted here is called electrolytic electrical discharge machining, and the pedestal 25 before the sensor chip 20 is joined is machined. That is, the pedestal 25 is immersed in a 35% sodium hydroxide aqueous solution, and a DC voltage of 40 to 50 V is applied between the platinum electrode provided in the aqueous solution and the metal needle in contact with the pedestal 25 to cause discharge. The pedestal 25 is etched by the heat generated by the electric discharge. Further, at the time of laser processing, the property that the laser beam (wavelength 10.6 μm) of the carbon dioxide gas is transmitted through the silicon and absorbed by the glass is used, and the laser beam is applied to the pedestal 25 with the sensor chip 20 bonded. Through irradiation, the through holes 56 can be selectively formed in the pedestal 25.

The metallization is chrome,
By depositing or sputtering copper, gold, aluminum or the like, the formed metal thin film is the conductive path 55.
Function as Further, a land 57 continuous with the conductive path 55 is formed on the lower surface of the pedestal 25 by metallization, and a bump 29 is formed on this land 57. When aluminum is used for metallization, bumps 29 are formed of gold or conductive synthetic resin, and when other metals are used, solder can be used in addition to the above materials. Further, as described in the first embodiment, if the structure in which the intermediate metal layer is formed between the aluminum and the solder is adopted, even if the conductive path 55 is aluminum, the land 57 is used as the intermediate metal layer for the solder. The bumps 29 can be formed. Other configurations are similar to those of the seventh embodiment, and the bump 29 is formed on the circuit pattern 32 of the circuit board 30 in a bare chip state in which the sensor chip 20 is joined to the pedestal 25.
To join. The land 57 need not be formed if it is unnecessary.

(Embodiment 10) This embodiment has the same structure as that of Embodiment 8 as shown in FIG. 10, but a p ^{+ type} semiconductor is used as the conductive path 53 formed in the sensor chip 20. Instead of the conductive path 55 formed on the pedestal 25 of the ninth embodiment, the through hole 5 is formed in the sensor chip 20.
6 is formed, and the conductive path 53 is formed by applying metallization to the inner peripheral surface of the through hole 56. The upper end of the conductive path 53 is continuous with the wiring pattern 28, and the lower end of the conductive path 53 is continuous with the electrode pad 57 formed on the lower surface of the sensor chip 20. Here, in order to prevent current leakage from the conductive path 53 to the semiconductor substrate 23, the inner peripheral surface of the through hole 56 is oxidized to form an insulating layer of silicon oxide, and the conductive layer is formed on the silicon oxide layer. The path 53 is formed. Therefore, as compared with the case of using the p ^{+ type} semiconductor described above, the current leakage is small, and the current capacity is large because the conductive path 53 is made of the metal film. As a result, the error due to current leakage is small and the pressure measurement accuracy is high.

To form the through hole 56, laser processing, focused ion beam processing, or the like is used. In laser processing,
For example, laser light of YAG laser (wavelength 1.06 μm)
Is irradiated on the sensor chip 20. In the focused ion beam processing, the focused ion beam is applied in a chlorine gas atmosphere. Molten gallium is used as the ion source for the focused ion beam.

The metal used for metallization is gold,
A thin film of tungsten, chromium, aluminum or the like is formed by vapor deposition or sputtering, and the thin film is used as the conductive path 53. The conductive path 53 is formed by applying metallization to the inner peripheral surface of the through hole 56 as described above, or by filling the through hole 56 with a conductive synthetic resin or a conductive paste (silver paste or the like). Good. Other configurations and operations are
Similar to the eighth embodiment, after the bumps 29 are face-down bonded to the circuit pattern 32 of the circuit board 30, the stress relaxation material 54 that seals the gap between the circuit board 30 and the sensor chip 20 over the entire circumference. To form. In this way, the airtight pressure reference chamber 27 is formed between the circuit board 30 and the sensor chip 20. The stress relaxation material 54 is formed of the same synthetic resin as that of the eighth embodiment or low melting point glass.

In the present embodiment, the electrode pads 57 are soldered (Pb-Sn based, A-based) without forming the bumps 29.
It may be bonded to the circuit pattern 32 of the circuit board 30 by using a u-Si system or the like) or a conductive paste (silver paste, nickel paste, copper paste, etc.). (Embodiment 11) In Embodiment 8, the stress relaxation material 5 is provided in the gap between the sensor chip 20 and the circuit board 30 over the entire circumference.
Although the airtight pressure reference chamber 27 was formed between the sensor chip 20 and the circuit board 30 by filling 4 with 4 in this embodiment, as shown in FIG. The pressure reference chamber 27 is formed between the diaphragm 24 and the cover plate 63 by joining the flat plate-shaped cover plate 63. The lid plate 63 is formed of glass such as heat-resistant glass, and the peripheral portion of the lid plate 63 is the sensor chip 2
0 is joined by the anodic joining method. Bump 29
As in the eighth embodiment, the sensor chip 20 is provided on the lower surface of the sensor chip 20, so that the sensor chip 20 is provided with the conductive path 53. Further, since the lid plate 63 is bonded to the lower surface of the sensor chip 20, the protrusion amount of the bump 29 is set to be larger than the thickness of the lid plate 63. With this configuration, even if the bumps 29 are crushed, the thickness does not become smaller than the thickness dimension of the cover plate 63, the contact area with the circuit pattern 32 can be kept small, and some of the bumps 29 are crushed. It is also possible to prevent the sensor body 1 from tilting due to excess.

In the above embodiment, the lid plate 63 is formed at a position displaced from the bump 29, but the positional relationship is such that a part of the lid plate 63 overlaps the bump 29, and the bump 29 passes through. A through hole may be formed in the cover plate 63.

[0066]

According to the first aspect of the present invention, the convex electrode, which is formed thinner than other portions and has a diaphragm that bends under pressure, is electrically connected to the strain gauge on the diaphragm. And a circuit board on which the sensor main body is surface-mounted together with electronic components that form a peripheral circuit by forming a circuit pattern of a thin conductive material on the surface of the base material. The electrode pads are formed so as to match the array of the convex electrodes of the above, and the convex electrodes are joined to the electrode pads by face down bonding. Since it can be surface-mounted on the substrate, there is an advantage that workability and productivity are improved.
Further, when the convex electrode is mounted on the circuit board, the sensor main body is automatically positioned at the position of the electrode pad by the surface tension of the solder, which also has the effect of facilitating the mounting work. Further, since the sensor body is mounted on the circuit board by face-down bonding, there is an advantage that the mounting area at the time of mounting and the protruding size from the circuit board are small and the pressure sensor as a whole including peripheral circuits can be downsized. is there. In addition, the distance between the electronic components that make up the peripheral circuits and the sensor body is reduced, making it less susceptible to noise, which improves sensitivity, and the convex electrodes are used to mount the circuit board. Since the contact area with the substrate is relatively small and the convex electrode can be deformed to some extent, the thermal stress due to the difference in the coefficient of thermal expansion between the sensor body and the circuit board can be relaxed, and a semiconductor with excellent temperature characteristics can be relaxed. There is an advantage that a pressure sensor can be obtained.

According to a second aspect of the present invention, a space is provided between the sensor chip having a diaphragm whose bottom wall is a diaphragm by opening the recess at the center of one surface of the semiconductor substrate in the thickness direction, and the recess. Since the sensor main body is composed of the pedestal that is airtightly bonded to the one surface of the sensor chip so as to be formed, by forming a space between the sensor chip and the pedestal, if this space is evacuated, The absolute pressure can be detected, and the pressure to be measured can be introduced into this space to detect the relative pressure with the ambient pressure of the sensor body.

According to the third aspect of the present invention, the convex electrode is provided on the other surface of the sensor chip so as to be fixed to the circuit board so as to surround at least the strain gauge and the convex electrode of the sensor body with the circuit board. And a second diaphragm that bends when pressure is applied to a part of a peripheral wall of the case, and a sensor detects a change in pressure received by the second diaphragm in a space surrounded by the case and the circuit board. It is filled with an inert liquid that transmits to the diaphragm of the main body and protects the strain gauge and the convex electrode from corrosion.Since the strain gauge and the convex electrode are immersed in the inert liquid, the strain gauge and the convex electrode are The electrode does not come into contact with air and corrosion is prevented, so that durability is improved.

According to the fourth aspect of the invention, since the case fixed to the circuit board is provided so as to surround the sensor body with the circuit board, a package for accommodating the entire circumference of the sensor body is unnecessary. There is an advantage that the package cost can be reduced. In the invention of claim 5, since the pedestal provided in the sensor body is fixed to the inner peripheral surface of the case, the sensor body is fixed to the case, and the case is fixed to the circuit board. Therefore, only the convex electrode is provided. Therefore, there is an advantage that the fixing strength of the sensor body can be improved as compared with the case where the sensor body is bonded to the circuit board.

In the invention of claim 6, the sensor chip is the first
The sensor chip is formed of a conductive semiconductor, and a first type semiconductor of high concentration is formed on the periphery of the diaphragm of the sensor chip.
Second conductive path is formed, and the pedestal has a second conductive path electrically connected to the first conductive path by applying metallization to the inner circumference of the through hole penetrating the portion corresponding to the first conductive path.
The conductive path is formed, and the strain gauge provided on the sensor chip and the convex electrode protruding on one surface of the pedestal are electrically connected via the first conductive path and the second conductive path,
Since the convex electrode is provided on the surface of the sensor body opposite to the surface on which the strain gauge is provided, stress from the convex electrode to the sensor body is unlikely to act on the diaphragm, enabling stable and highly accurate pressure measurement. Has the advantage that Further, since the strain gauge is exposed on the surface of the sensor body opposite to the surface facing the circuit board, the probe for conductivity inspection is brought into contact with the strain gauge side so that the convex electrodes and the circuit board are mounted after mounting the sensor body. There is an advantage that it is possible to inspect the connection state with and the characteristics of the strain gauge can be adjusted after mounting the sensor main body by trimming the strain gauge with laser light.

According to a seventh aspect of the present invention, there is provided a plate having a diaphragm which is formed thinner than other portions and which is bent by receiving pressure so that a convex electrode electrically connected to a strain gauge on the diaphragm is projected on one surface. -Shaped sensor body, a circuit board on which a circuit pattern made of a thin conductive material is formed on the surface of a base material that is thicker than the sensor body, and electronic components that form peripheral circuits are mounted, and a circuit board that penetrates in the thickness direction of the circuit board. The first lid plate fixed to the circuit board so as to close one opening surface of the housing hole with the sensor main body housed in the provided housing hole fixed to one surface, and the other opening surface of the housing hole. The second cover plate is fixed to the circuit board so as to be closed, and a part of the circuit pattern is arranged so as to extend into the opening of the housing hole and match the array of the convex electrodes of the sensor body. Forming a lead piece On the other hand, the convex electrode is joined from the inside of the housing hole, and the sensor body is mounted within the thickness of the circuit board, so the mounting space of the sensor body can be greatly reduced. There is.
Also, since the lead piece is projected inside the storage hole,
By the elasticity of the lead piece, the stress acting on the convex electrode can be relieved, and by covering the storage hole with the lid plate, it is possible to mount circuit components on the lid plate as necessary. There is an advantage that the mounting efficiency including the peripheral circuits is increased.

In the invention of claim 8, since at least a part of the gap formed between the inner peripheral surface of the housing hole and the outer peripheral surface of the sensor main body is filled with the gel-like stress relaxation material, the sensor main body is filled. There is an advantage that it is possible to reduce the vibration and shock to the. According to the invention of claim 9, since the sensor chip has the cavity formed inside the semiconductor substrate to form the diaphragm on a part of the peripheral wall of the cavity, the sensor body is used.
There is an advantage that the pedestal need not be joined to the sensor chip and the material cost can be reduced.

In the tenth aspect of the present invention, the sensor chip is formed by opening the recess in the center of one surface of the semiconductor substrate in the thickness direction, so that the bottom wall of the recess serves as the diaphragm, and the sensor body is used. A conductive path penetrating in the thickness direction of the sensor body is formed in the peripheral portion, and a convex electrode electrically connected to the strain gauge through the conductive path is provided on the one surface of the sensor chip so as to project. A stress relieving material that hermetically seals the space between the recess and the circuit board and relieves the stress of the convex electrode is filled between the peripheral portion and the circuit board. By providing the same effect as that of the sixth aspect of the invention, and by forming the airtight space between the recess and the circuit board by filling the stress relaxation material between the peripheral portion of the sensor chip and the circuit board,
There is an advantage that the pedestal need not be joined to the sensor chip and the material cost can be reduced. Moreover, the stress relaxation material increases the fixing strength of the sensor chip to the circuit board by supporting the convex electrode, and relaxes the stress acting on the sensor chip to enable stable and accurate pressure measurement. There are advantages.

According to the eleventh aspect of the present invention, the sensor body has a sensor body whose bottom wall is formed as a diaphragm by forming a recess at the center of one surface of the semiconductor substrate in the thickness direction. A conductive path penetrating in the thickness direction of the sensor body is formed in the surrounding portion, and a convex electrode electrically connected to the strain gauge through the conductive path is provided on the one surface of the sensor chip so as to project. A cover plate, which has a thickness smaller than the protruding size of the convex electrode from the sensor chip and which hermetically seals the recess, is fixed to, and has the same effect as that of claim 6. By providing the cover plate within the projecting dimension of the convex electrode, there is an advantage that the thickness dimension of the sensor body can be reduced as compared with the case where the pedestal is provided. Also, even if the convex electrode is deformed during mounting, the protruding dimension of the convex electrode from the sensor body does not become smaller than the thickness of the lid plate, so the contact area of the convex electrode with the circuit board is small. Therefore, there is an advantage that the effect of stress relaxation due to the convex electrode can be maintained.

According to the twelfth aspect of the present invention, the sensor chip is formed of the first conductivity type semiconductor, and the conductive path is formed of the high concentration second semiconductor.
Since the conductive path is formed of the conductive semiconductor, the conductive path can be formed by the semiconductor manufacturing process, which is advantageous in that the manufacturing is easy. According to the thirteenth aspect of the present invention, the conductive path is formed by applying metallization to the inner peripheral surface of the through hole penetrating the semiconductor substrate forming the sensor chip via the insulating layer. There is the advantage that the leakage can be reduced and the conductivity of the conductive path can be increased by the metallized metal, which results in an increase in the sensitivity of the pressure measurement and an increase in the measurement accuracy.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment.

FIG. 2 is a cross-sectional view showing a second embodiment.

FIG. 3 is a sectional view showing a third embodiment.

FIG. 4 is a cross-sectional view showing a fourth embodiment.

FIG. 5 is a cross-sectional view showing a fifth embodiment.

FIG. 6 is a sectional view showing a sixth embodiment.

FIG. 7 is a cross-sectional view showing a seventh embodiment.

FIG. 8 is a sectional view showing an eighth embodiment.

FIG. 9 is a cross-sectional view showing a ninth embodiment.

FIG. 10 is a cross-sectional view showing Embodiment 10.

FIG. 11 is a sectional view showing an eleventh embodiment.

FIG. 12 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 Sensor Main Body 2 Electronic Component 17 Lead Piece 20 Sensor Chip 22 Strain Gauge 24 Diaphragm 25 Pedestal 29 Bump 30 Circuit Board 32 Circuit Pattern 33 Cover Plate 34 Cover Plate 35 Storage Hole 37 Stress Relief Material 40 Case 41 Diaphragm 42 Inert Liquid 51 Cavity 53 Conductive Path 54 Stress Relief Material 55 Conductive Path 56 Through Hole 63 Cover Plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigenori Takami 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd. (72) Takamasa Sakai, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works Co., Ltd.

Claims (13)

[Claims] 1. A plate-shaped sensor body, which has a diaphragm formed thinner than other portions and which bends when receiving pressure, and a convex electrode electrically connected to a strain gauge on the diaphragm protrudes over one surface. , A circuit board on which a sensor body is surface-mounted together with electronic components that form a peripheral circuit by forming a circuit pattern of a thin conductive material on the surface of the base material, and the circuit pattern has an array of convex electrodes of the sensor body. A semiconductor pressure sensor, wherein electrode pads arranged so as to coincide with each other are formed, and convex electrodes are joined to the electrode pads by face-down bonding. 2. The sensor body forms a space between a sensor chip having a diaphragm on the bottom wall of the recess by opening the recess at the center of one surface of the semiconductor substrate in the thickness direction, and the recess. 2. A pedestal that is hermetically joined to the one surface of the sensor chip as described above.
A semiconductor pressure sensor according to claim 1. 3. The convex electrode is provided so as to protrude from the other surface of the sensor chip, and has a case fixed to the circuit board so as to surround at least the strain gauge and the convex electrode of the sensor body with the circuit board. A second diaphragm that bends under pressure is provided on a part of the peripheral wall of the case, and the pressure change received by the second diaphragm is transmitted to the diaphragm of the sensor body in the space surrounded by the case and the circuit board. The semiconductor pressure sensor according to claim 2, wherein the strain gauge and the convex electrode are filled with an inert liquid that prevents corrosion. 4. The semiconductor pressure sensor according to claim 2, further comprising a case fixed to the circuit board so as to surround the sensor body with the circuit board. 5. The semiconductor pressure sensor according to claim 4, wherein a pedestal provided on the sensor body is fixed to an inner peripheral surface of the case. 6. The sensor chip is formed of a first conductivity type semiconductor, a first conductive path made of a high concentration second type semiconductor is formed in a peripheral portion of a diaphragm of the sensor chip, and a first base is formed on a pedestal. The second conductive path electrically connected to the first conductive path is formed by applying metallization to the inner circumference of the through hole penetrating the portion corresponding to the conductive path, and strain applied to the sensor chip is formed. 3. The semiconductor pressure sensor according to claim 2, wherein the gauge and the convex electrode projectingly provided on one surface of the pedestal are electrically connected to each other through the first conductive path and the second conductive path. 7. A plate-shaped sensor main body having a diaphragm formed thinner than other portions and bent under pressure to electrically connect a convex electrode electrically connected to a strain gauge on the diaphragm to one surface. , A circuit board on which a circuit pattern made of a thin conductive material is formed on the surface of a base material that is thicker than the sensor body, and electronic components that form peripheral circuits are mounted, and a storage hole that penetrates in the thickness direction of the circuit board. A first lid plate fixed to the circuit board so as to close one opening surface of the housing hole with the sensor main body being fixed to one surface, and a circuit so as to close the other opening surface of the housing hole. Second fixed to the substrate
Part of the circuit pattern that extends into the opening of the housing hole and forms a lead piece that is arranged so as to match the array of the convex electrodes of the sensor body. A semiconductor pressure sensor characterized in that a convex electrode is joined from the inside of a housing hole. 8. The gel stress relieving material is filled in at least a part of a gap formed between the inner peripheral surface of the housing hole and the outer peripheral surface of the sensor body. Semiconductor pressure sensor. 9. The semiconductor pressure sensor according to claim 1, wherein the sensor body is a sensor chip in which a cavity is provided inside a semiconductor substrate to form a diaphragm on a part of a peripheral wall of the cavity. 10. The sensor body is a sensor chip in which a bottom wall of the recess serves as a diaphragm by opening the recess in the center of one surface of the semiconductor substrate in the thickness direction. Is formed with a conductive path penetrating in the thickness direction of the sensor body, and a convex electrode electrically connected to the strain gauge through the conductive path is projectingly provided on the above-mentioned one surface of the sensor chip, and with the peripheral portion of the sensor chip. 2. A stress relaxation material for airtightly sealing a space between the recess and the circuit board and relaxing stress of the convex electrode is provided between the circuit board and the circuit board. Semiconductor pressure sensor. 11. The sensor body is a sensor chip in which a bottom wall of the recess serves as a diaphragm by opening the recess in a central portion of one surface of the semiconductor substrate in the thickness direction, and a peripheral portion of the sensor chip surrounding the diaphragm. Is formed with a conductive path penetrating in the thickness direction of the sensor body, and a convex electrode electrically connected to the strain gauge through the conductive path is provided on the one surface of the sensor chip so as to project. 2. The semiconductor pressure sensor according to claim 1, wherein the thickness of the electrode is smaller than the protruding size of the sensor chip from the sensor chip, and a cover plate that hermetically seals the recess is fixed. 12. The semiconductor pressure sensor according to claim 10, wherein the sensor chip is formed of a first conductivity type semiconductor, and the conductive path is formed of a high concentration second conductivity type semiconductor. . 13. The conductive path is formed by applying metallization to the inner peripheral surface of a through hole penetrating the semiconductor substrate forming the sensor chip via an insulating layer. The semiconductor pressure sensor according to claim 11.