JP3285971B2 - Semiconductor pressure sensor - Google Patents

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 for detecting a pressure difference applied to both sides of a diaphragm, and more particularly to an absolute pressure type semiconductor pressure sensor in which a reference pressure is vacuum.

[0002]

2. Description of the Related Art A semiconductor pressure sensor for applying a reference pressure and a pressure to be measured to both surfaces of a thin diaphragm portion, respectively, includes an absolute pressure sensor for setting a reference pressure to a vacuum and a gauge pressure sensor for setting a reference pressure to an atmospheric pressure. Are roughly divided into In a pressure sensor of this type, a sensor chip is housed in a metal can or a package and used in a stable state. When plastic is used as the package material, the absolute pressure sensor may have a structure as shown in FIG.

That is, a glass pedestal 2 is bonded to the center of a plastic package 1. A semiconductor pressure sensor chip 3 having a diaphragm structure is mounted on the pedestal 2, and a detection signal from the strain detecting element is guided to a lead 5 by a wire 4. The lower part of the sensor chip 3 is a vacuum chamber 6, which performs pressure measurement using this as a reference pressure. Since the lead 5 penetrates through the package 1, an adhesive is applied to keep the airtightness inside the package by applying an adhesive.
To form When the assembling of the internal structure is completed, a pressure medium introducing member 8 made of plastic is fitted over the assembling opening of the package 1 and the two are joined with an adhesive 9 to complete the absolute pressure sensor.

In this absolute pressure sensor, a pressure medium to be measured is introduced from a pressure medium introduction hole 10 formed in an introduction member 8, and the pressure is applied to the upper surface of a sensor chip 3.
Since the lower surface of the sensor chip 3 is vacuum, a strain corresponding to the absolute pressure of the pressure medium is applied to the sensor chip 3, and the strain, that is, the absolute value of the medium pressure is detected by the strain detecting element.

[0005]

The pressure sensor having the structure shown in FIG. 3 uses a package having a structure different from a plastic package of a normal gauge pressure sensor. That is,
The package for the gauge pressure sensor has a pressure medium introduction hole at the center, and has a structure in which the introduced medium passes through the pedestal and is directly applied to the lower surface of the sensor chip. However,
In the absolute pressure sensor, since the lower surface of the sensor chip is a vacuum chamber, a through hole for introducing medium pressure cannot be formed in the pedestal. For these reasons, a package and an introduction member peculiar to the absolute pressure sensor have been conventionally used, but this has a drawback that a mold cost, management cost, and the like are required, which leads to an increase in cost.

An object of the present invention is to make it possible to manufacture an absolute pressure sensor using a normal gauge pressure sensor package.

[0007]

In order to achieve the above object, a semiconductor pressure sensor according to the present invention comprises a package having a pressure medium introduction hole in a central portion, and a groove communicating with the pressure medium introduction hole formed on a bottom surface. a pedestal mounted on the inner surface of the packages designed, is mounted on the pedestal, a semiconductor pressure sensor chip to form a vacuum chamber to the base side, the vacuum chamber of the sensor chip to close the assembly opening of the package And a lid that forms a closed space into which the pressure medium is introduced on the opposite side.

[0008]

The package for a normal gauge pressure sensor has a pressure medium introduction hole. Therefore, when a conventional pedestal is mounted on the inner surface of the package, the introduction hole is closed, and the pressure medium cannot be introduced inside.
On the other hand, in the pedestal of the present invention, since the groove communicating with the introduction hole is formed, the pressure medium can be introduced inside. Therefore, according to the present invention, since the absolute pressure sensor can be configured using a normal gauge pressure sensor package, the cost can be reduced by using a common manufacturing process and parts.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional structural view of an absolute pressure sensor showing an embodiment of the present invention, 20 is a plastic package for a normal gauge pressure sensor, 21 is a plastic or aluminum lid for closing an assembly opening thereof, 22 is a lid. It is a groove for introducing a pressure medium formed on the lower surface of the glass pedestal 2.

The package 20 has a flat portion for mounting the pedestal at the center, and the pressure medium introduction chamber 23 is located above the flat portion and the pressure medium introduction hole 10 is located below the flat portion. Pedestal 3 is package 20
The groove 2 formed on the lower surface of the
2 communicates with the introduction hole 10, the pressure medium supplied from the outside is introduced into the introduction chamber 23, and is applied to the upper surface of the sensor chip 3 mounted on the upper surface of the pedestal 2. The portion where the detection signal from the sensor chip 3 is transmitted to the lead 5 via the wire 4 and the portion where the lead sealing portion 7 is formed with an adhesive are the same as those in FIG. When such internal assembly is completed, the assembly opening of the package 20 is closed with the lid 21 to complete the assembly.

FIG. 2 shows a semiconductor pressure sensor chip 3 and a pedestal 2.
(A) is a longitudinal sectional view,
(B) is a cross-sectional view, and (c) is a bottom view. As shown in FIG. 2B, the pressure medium introduced from the introduction hole 10 is:
Since the sensor chip 3 can reach the upper surface of the sensor chip 3 through the groove 22 of the pedestal 2, the sensor chip 3 can detect the pressure difference between the vacuum chamber 6 and the pressure medium, that is, the absolute pressure. Since the groove 22 can be easily formed by a dicing saw, it does not cause a cost increase.

The above-described absolute pressure sensor of the present invention uses the same package 20, lid 21, lead 5, and wire 4 as a normal gauge pressure sensor, so that not only the common use of parts but also the common use of the manufacturing process is achieved. I can do it. That is, the groove 22 is formed in advance on the package bonding surface of the pedestal 2, and the sensor chip 3 is bonded to the opposite surface. Chips joined in this way
The pedestal pairs 3 and 2 are assembled into the package 20 in the same process as a normal gauge pressure sensor, the lead sealing portion 7 is formed, and the lid 21 is bonded. This process, except for lead sealing,
It is the same as the gauge pressure sensor.

[0013]

As described above, according to the present invention, in a semiconductor pressure sensor using a semiconductor pressure sensor chip, an absolute pressure sensor can be manufactured using a normal gauge pressure sensor package. The cost can be reduced by using a common manufacturing process and parts.

[Brief description of the drawings]

FIG. 1 is a sectional structural view showing one embodiment of the present invention.

FIG. 2 is a structural view showing a pedestal of the present invention as a single body.

FIG. 3 is a sectional structural view of a conventional absolute pressure sensor.

[Explanation of symbols]

2 ... pedestal, 3 ... semiconductor pressure sensor chip, 4 ... wire,
Reference numeral 5: lead, 6: vacuum chamber, 7: lead sealing portion, 10: pressure medium introduction hole, 20: package for gauge pressure sensor, 2
1 ... lid, 22 ... pressure medium introduction groove.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 29/84 G01L 19/00

Claims (1)

(57) [Claims] A package having a pressure medium introduction hole in a central portion, a pedestal formed on a bottom surface with a groove communicating with the pressure medium introduction hole, and mounted on an inner surface of the package. A semiconductor pressure sensor chip mounted on the base to form a vacuum chamber on the pedestal side; and a closed space into which a pressure medium is introduced on a surface of the sensor chip opposite to the vacuum chamber by closing an assembly opening of the package. A semiconductor pressure sensor, comprising: a lid to be formed.