JPH11337432A - Semiconductor pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor pressure sensor with satisfactory temperature characteristics capable of accurate pressure measurement. SOLUTION: A semiconductor pressure sensor is formed by supporting and housing a semiconductor pressure sensor chip 1 with a diaphragm 11, which is formed in a thin-walled shape by the formation of a recessed part, in the recessed part of a package 3 via a supporting substrate 20 by solder 6. In the semiconductor pressure sensor, metal thin films 21 and 32 are formed on one surface of the supporting substrate 20 and the side wall 33 of the recessed part of the package 3, the one surface of the supporting substrate 20 is joined to the side wall 33 of the recessed part of the package 3 by solder 6, and the other surface of the supporting substrate 20 is joined to the side surface of the semiconductor pressure sensor chip 1. By this, the semiconductor pressure sensor chip 1 is supported and housed in the recessed part of the package 3 via the supporting substrate 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor pressure sensor in which a semiconductor pressure sensor chip having a diaphragm is housed in a package via a support substrate.

[0002]

2. Description of the Related Art In general, a semiconductor pressure sensor measures a pressure in a minute pressure region. As shown in FIG. 4, a semiconductor pressure sensor has a diaphragm 11 formed in a thin shape by forming a concave portion in a silicon substrate. Semiconductor pressure sensor chip 1
Is joined to one surface of the supporting substrate 2 forming a pedestal by anodic bonding or the like, and the other surface of the supporting substrate 2 is
The semiconductor pressure sensor chip 1 is supported and housed in a concave portion of the package 3 by being joined to a plastic package 3 on which the semiconductor package 1 is disposed.

The support substrate 2 serves to relieve the stress applied from the package 3 and the like to the semiconductor pressure sensor chip 1, and a glass or silicon substrate having a thermal expansion coefficient close to that of a silicon substrate is used.

The bonding between the support substrate 2 and the package 3 is performed by solder 6. In order to improve the joint with the solder 6,
A plating layer 32 made of a material which is easily eutectic bonded to the solder 6 is formed on a bonding surface of the package 3 with the support substrate 2.
A metal thin film layer 21 made of a material that can be easily eutectic-bonded to the solder 6 is formed on the bonding surface of the support substrate 2 with the package 3.

The electrode pads on the surface of the semiconductor pressure sensor chip 1 and the leads 4 are connected by gold or aluminum wires 5. A plurality of piezoresistors 12 are formed on the surface of the semiconductor pressure sensor chip 1 by diffusion, and a plurality of piezoresistors 12 are connected to each other to form a Wheatstone bridge circuit. A current or the like is supplied from the lead 4 to the Wheatstone bridge circuit, and the piezoresistor 12
By detecting the change in the resistance value as a change in voltage, a change in pressure transmitted through the pressure introducing pipe 31 can be extracted as a change in an electric signal.

[0006]

However, in the above-described semiconductor pressure sensor, it is necessary to perform the bonding with the solder 6 at a temperature higher than the melting point of the solder 6. At this temperature, the solder 6, the package 3, the support substrate 2, and the semiconductor pressure sensor chip 1 do not exert any stress on each other, but are at a temperature higher than the melting point (generally higher than 200 ° C.). Therefore, as the semiconductor pressure sensor cools down to the temperature at which it is used, solder 6
Since the physical characteristics of the semiconductor substrate and the support substrate 2 to which the semiconductor pressure sensor chip 1 is bonded are different, forces are exerted on each other.

In general, the thermal expansion coefficient of the solder 6 is larger than that of the semiconductor pressure sensor chip 1 and the supporting substrate 2, and the solder 6 is at a room temperature level.
And the support substrate 2 is more contracted. Further, the solder 6 rises due to the shrinkage and exerts a force to push up the support substrate 2 to which the semiconductor pressure sensor chip 1 is joined from below,
A part of this force acts on the semiconductor pressure sensor chip 1 to distort the piezoresistor 12 formed on the diaphragm 11.

As a result, the semiconductor pressure sensor is used in a state of receiving a stress from a medium other than the pressure medium to be detected, and accurate pressure detection is not performed. There is a problem that the temperature characteristics of the sensor are distorted (reduced linearity).

The present invention has been made in view of the above points, and an object of the present invention is to provide a semiconductor pressure sensor capable of accurately measuring pressure and having good temperature characteristics.

[0010]

According to the first aspect of the present invention,
A semiconductor pressure sensor chip having a diaphragm formed in a thin shape by forming a concave portion, a semiconductor pressure sensor that is supported and housed in a concave portion of a package by solder through a support substrate, and one side of the support substrate A metal thin film is formed on the side wall of the concave portion of the package, and one surface of the support substrate and the side wall of the concave portion of the package are joined by soldering, and the other surface of the support substrate is joined with the side surface of the semiconductor pressure sensor chip. Thus, the semiconductor pressure sensor chip is supported and housed in the recess of the package via the support substrate.

According to a second aspect of the present invention, in the first aspect of the invention, at least one of the metal thin films formed on one surface of the support substrate and a side wall of the concave portion of the package is formed in a slit shape. It is characterized by the following.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the semiconductor pressure sensor according to the first embodiment of the present invention. The semiconductor pressure sensor according to the present embodiment includes one of two support substrates 20 each forming a pedestal on both side surfaces of a semiconductor pressure sensor chip 1 having a diaphragm 11 formed thin by forming a recess in a silicon substrate. The surfaces are joined by anodic joining or the like. The other surface of the support substrate 20 is joined to the inner surface of the side wall 33 forming the recess of the plastic package 3 in which the pressure introducing tube 31 is disposed at the center, so that the semiconductor pressure sensor chip 1 It is supported and stored.

The support substrate 20 serves to relieve the stress applied from the package 3 or the like to the semiconductor pressure sensor chip 1, and a glass or silicon substrate having a thermal expansion coefficient close to that of the silicon substrate is used.

The bonding between the support substrate 20 and the side wall 33 of the package 3 is performed by the solder 6. In order to improve the bonding with the solder 6, a plating layer 32 as a metal thin film made of a material that can be easily eutectic bonded to the solder 6 is formed on the bonding surface (the inner surface of the side wall 33) of the package 3 with the supporting substrate 20. And
A metal thin film layer 21 made of a material that can be easily eutectic-bonded to the solder 6 is formed on a surface of the support substrate 20 to be bonded to the package 3. As a structure that can be easily soldered, for example, when Au—Si solder is used as the solder 6,
Au is used as the material of the metal thin film layer 21. Au plating is also applied to the plating layer 32 formed on the inner surface of the side wall 33 of the package 3.

If the metal thin film layer 21 is composed of a plurality of metal films, the adhesion between the solder 6 and the support substrate 20 is improved, and the metal 6 is hardly peeled off.

The electrode pads on the surface of the semiconductor pressure sensor chip 1 and the leads 4 are connected by gold or aluminum wires 5. A plurality of piezoresistors 12 are formed on the surface of the semiconductor pressure sensor chip 1 by diffusion, and a plurality of piezoresistors 12 are connected to each other to form a Wheatstone bridge circuit. A current or the like is supplied from the lead 4 to the Wheatstone bridge circuit, and the piezoresistor 12
By detecting the change in the resistance value as a change in voltage, a change in pressure transmitted through the pressure introducing pipe 31 can be extracted as a change in an electric signal.

According to the present embodiment, even when the solder 6 is thermally contracted due to a temperature change, since the bonding portion by the solder 6 exists in the side direction of the semiconductor pressure sensor chip 1, the supporting substrate 20 can be lifted. No force acts and the stress on the piezoresistor 12 is reduced. Therefore, the occurrence of distortion (decrease in linearity) in the temperature characteristics of the semiconductor pressure sensor due to a temperature change is reduced, and the semiconductor pressure sensor chip 1
Temperature characteristics are improved. FIG. 2 is a sectional view of a semiconductor pressure sensor according to the second embodiment of the present invention. The semiconductor pressure sensor according to this embodiment is the same as the semiconductor pressure sensor according to the first embodiment, except that the metal thin film layer 2 formed on the support substrate 20 is formed.
1 is a slit-shaped metal thin film layer 22 formed by utilizing an etching technique.

According to this embodiment, when the solder 6 is thermally contracted due to a temperature change, the solder 6 is absorbed by the slit portion of the metal thin film layer 22, so that the influence of the stress from the side of the semiconductor pressure sensor chip 1 is reduced. Further, the temperature characteristics of the semiconductor pressure sensor chip 1 are further improved, and the temperature characteristics of the semiconductor pressure sensor chip 1 are further improved.

FIG. 3 is a sectional view of a semiconductor pressure sensor according to a third embodiment of the present invention. The semiconductor pressure sensor according to the present embodiment is different from the semiconductor pressure sensor according to the first embodiment in that the plating layer 32 formed on the inner surface of the side wall 33 of the package 3 is formed by using a plating pattern forming technique. This is the layer 33.

According to the present embodiment, when the solder 6 is thermally contracted due to a temperature change, it is absorbed by the slit portion of the plating layer 33, so that the influence of the stress from the side of the semiconductor pressure sensor chip 1 is further increased. As a result, the temperature characteristics of the semiconductor pressure sensor chip 1 are further improved.

In the second and third embodiments, either the metal thin film layer 21 or the plating layer 32 is formed in a slit shape, but it goes without saying that both may be formed in a slit shape. No.

[0022]

As described above, according to the first aspect of the present invention, a semiconductor pressure sensor chip having a diaphragm formed thin by forming a concave portion is packaged by soldering via a supporting substrate. In the semiconductor pressure sensor supported and housed in the concave portion, a metal thin film is formed on one surface of the support substrate and the side wall of the concave portion of the package, and the one surface of the support substrate and the side wall of the concave portion of the package are soldered. And the other surface of the support substrate is joined to the side surface of the semiconductor pressure sensor chip, so that the semiconductor pressure sensor chip is supported and housed in the recess of the package via the support substrate. Even when the heat-shrinkage occurs, the joint portion by solder exists in the side direction of the semiconductor pressure sensor chip, so that the support substrate can be lifted. Force does not act, the stress on the diaphragm is relaxed. Therefore, it is possible to provide a semiconductor pressure sensor in which the occurrence of distortion of the temperature characteristic (reduction in linearity) due to a temperature change is reduced and the temperature characteristic of the semiconductor pressure sensor chip is improved.

According to a second aspect of the present invention, in the first aspect of the invention, at least one of the metal thin films formed on one surface of the support substrate and the side wall of the concave portion of the package is formed in a slit shape. When the solder is thermally contracted due to the temperature change, the solder is absorbed by the slit portion of the metal thin film, so that the influence of the stress from the side direction of the semiconductor pressure sensor chip is further reduced.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a semiconductor pressure sensor according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a semiconductor pressure sensor according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a semiconductor pressure sensor according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor pressure sensor chip 2, 20 Support substrate 3 Package 4 Lead 5 Wire 6 Solder 11 Diaphragm 12 Piezoresistor 21 Metal thin film layer 22 Slit-shaped metal thin film layer 31 Pressure introduction pipe 32 Plating layer 33 Side wall 34 Slit-shaped plating layer

Claims (2)

[Claims] 1. A semiconductor pressure sensor comprising a semiconductor pressure sensor chip having a diaphragm formed in a thin shape by forming a concave portion and being supported and housed in a concave portion of a package by solder via a supporting substrate. A metal thin film is formed on one surface of the package and the side wall of the concave portion of the package, and one surface of the support substrate and the side wall of the concave portion of the package are joined by soldering. Wherein the semiconductor pressure sensor chip is supported and housed in a concave portion of the package via a support substrate by bonding to the side surface of the semiconductor pressure sensor chip. 2. The semiconductor pressure sensor according to claim 1, wherein at least one of the metal thin films formed on one surface of the support substrate and a side wall of the concave portion of the package is formed in a slit shape.