JPH09133594A - Semiconductor pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and inexpensive semiconductor pressure sensor which is insusceptible to parasitic capacity and external field and can detect the pressure accurately. SOLUTION: The semiconductor pressure sensor comprises a sensor chip 6 where a silicon substrate 1 having a diaphragm part 2 deformable with the pressure to be measured is bonded to a glass substrate 3 having a fixed electrode 4, a cap part 13 having a through hole 12, and a base 19 having a region metallized through plating. The sensor chip 6 and an IC chip 20 are disposed in the metallized region of the base 19.

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 used for pressure detection in automobiles, pressure detection in home appliances and the like.

[0002]

2. Description of the Related Art A pressure sensor shown in FIG. 2 is generally known as an electrostatic capacitance type pressure sensor of this type. The illustrated pressure sensor is a capacitance type pressure sensor, in which a diaphragm portion 2 that deforms in response to pressure is formed on a silicon substrate 1, and a fixed electrode 4 is formed on a glass substrate 3. As shown in the figure, the silicon substrate 1 and the glass substrate 3 are joined together at a part thereof, so that the cavity portion 5 is formed below the diaphragm portion 2.

A sensor chip 6 is constituted by the silicon substrate 1 and the glass substrate 3, and the sensor chip 6 is adhered onto the pedestal 27 by the glass substrate 3. Further, a passage 8 for introducing atmospheric pressure or introducing a pressure to be compared with the measured pressure is formed in the pedestal 27 on which the glass substrate 3 constituting the sensor chip 6 and the sensor chip 6 are arranged. A lead terminal 29, which is also formed at the time of molding, is arranged on the pedestal 27, and the lead terminal 29 and the fixed electrode 4 are electrically connected by the lead wire 10.

The sensor chip 6 is provided with a lateral hole so that the fixed electrode 4 can be pulled out to the outside. After that, in order to separate the cavity 5 and the area outside the sensor chip,
The lateral holes are sealed with the sealing agent 11. And pedestal 2
7 and a cap 13 of a molding material as a cover member having a through hole 12 for introducing the measured pressure are sealed by ultrasonic welding to form a mold package 36.

The mold package 36 is installed on a hybrid integrated circuit substrate (hereinafter referred to as HIC substrate) 37. And a board built-in case 35 that houses the entire HIC board 37
The structure is covered with.

In the illustrated capacitance type pressure sensor, when pressure is applied to the diaphragm portion 2, the diaphragm portion 2 is deformed according to the magnitude of the pressure. Due to the deformation of the diaphragm portion 2, the gap between the diaphragm portion 2 and the fixed electrode 4 changes. Here, there is a relationship between the diaphragm portion 2 and the fixed electrode 4 as shown in Expression 1 below. Note that c is capacitance, ξ is the permittivity of air, A is the electrode area, and d is the inter-electrode gap.

[0007]

(Equation 1)

Therefore, the capacitance changes due to the change in the gap, and since there is a certain correlation between the force and the gap, it is possible to know the pressure by detecting the capacitance. it can.

[0009]

In the conventional electrostatic capacitance type pressure sensor, the electrostatic capacitance which changes depending on the pressure to be detected is as small as 1 pF to 2 pF and is easily affected by the parasitic capacitance, so that it is not the pressure to be detected. It was impossible to detect an accurate pressure due to the large influence of. Further, there is a problem that even if the measurement position of the pressure sensor is changed, the electric field in the external field changes and the detected pressure changes.

Further, in this configuration, the board built-in case 35,
The number of parts such as the HIC board 37 and the mold package 36 is large, which is unsuitable for downsizing and low cost.

An object of the present invention is to reduce the influence of parasitic capacitance and external electric field and to perform accurate pressure detection.
Moreover, it is to provide a small-sized and low-cost semiconductor pressure sensor.

[0012]

According to the present invention, a detection element portion having a silicon substrate having a diaphragm portion that is deformed by a pressure to be measured, an upper outer case having a pressure inflow through hole, and a wiring pattern by plating. In a semiconductor pressure sensor composed of a lower outer case having a metal-bonded region and an electronic component, an IC chip in which the detection element section and a detection circuit for detecting the detection element section are integrated. A semiconductor pressure sensor is obtained which is installed in a region of the lower outer case where metal is attached.

[0013]

According to the present invention, the sensor chip and the electronic components are directly mounted on the sealing resin body which is formed by resin molding patterned by plating, so that the HIC substrate and the case are unnecessary, and the size and cost can be reduced. . In addition, since a shield pattern is formed on the sealing body by plating and the sensor chip and IC are mounted on it, parasitic capacitance and external electric field are shielded so that they are not affected and accurate pressure detection can be performed. it can.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a semiconductor pressure sensor according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the structure of a semiconductor pressure sensor of the present invention. The semiconductor pressure sensor includes a silicon substrate 1 having a diaphragm portion 2 forming a movable electrode that is deformed by a pressure to be measured and a cavity portion 5 provided below the diaphragm portion 2, and a fixed electrode 4.
And a glass substrate 3 having a through-hole 8 for introducing a pressure for introducing atmospheric pressure or for comparing a pressure to be measured, and a sensor chip 6 functioning as a detection element portion.

In the sensor chip 6, a lateral hole is formed between the silicon substrate 1 and the glass substrate 3 so that the fixed electrode 4 can be pulled out. This lateral hole is sealed with a sealant 11 in order to isolate the cavity 5 from the outside of the sensor chip. The sensor chip 6 is formed on a pedestal 19 as a lower outer case made of resin and is fixed by an adhesive on a conductor pattern 18 which also serves as a shield material. The conductor pattern 18 is a wiring pattern formed on the pedestal 19 and is grounded to GND. The fixed electrode 4 and the IC chip 20 are electrically connected by the lead wire 10. The lead terminal 14 is integrally molded with the pedestal 19 with resin. The conductor pattern 18 provided below the sensor chip 6 functions as a shield material, reduces the parasitic capacitance between the silicon substrate 1 and the fixed electrode 4 of the sensor chip 6, and removes the influence of external electric field noise. do.

The pedestal 19 and the through hole 1 for introducing the measured pressure.
Mold material cap 1 as a cover member provided with 2
3 is sealed by ultrasonic welding to form a mold package 16. Normally, the sensor chip 6 is installed in the mold package 16, and the mold package 16 is mounted on the hybrid IC substrate (HIC substrate) on which the detection circuit is mounted. However, between the silicon substrate 1 of the sensor chip 6 and the fixed electrode 4. In order to reduce the parasitic capacitance that enters, the detection circuit is formed as a one-chip IC in the mold package 16 together with the sensor chip 6. The sensor chip 6 and the IC chip 20 are mounted on the mold package 16 and adhered onto the conductor pattern 18 on the pedestal 19 by an adhesive. IC chip 20 and sensor chip 6
Is connected by a connecting lead wire 10 so as to be short so that there is almost no parasitic capacitance due to routing. Also, conductor pattern 1
When 8 is grounded to GND through the lead terminal 14, the influence of the parasitic capacitance due to the dielectric constant of the resin of the pedestal 19 can be eliminated, and the effect of shielding the external electric field can be obtained. Resistors and other electronic components 22 are mounted on the conductor pattern 23 formed by plating on the pedestal 19. Here, the connection between the signal line and the lead terminal is omitted. A resin molded cap (hereinafter, referred to as a cap portion) 13 as a cover member (upper outer case) having a passage 12 for introducing a measured pressure is sealed with a pedestal 19 by ultrasonic welding. Then, silicon gel (or silicon oil) 21 is injected from the through hole 12 of the cap portion 13,
The deterioration of the lead wire 10, the pads of the sensor chip 6 and the IC chip 20 and the conductor pattern 18 is prevented.

[0017]

According to the present invention, the lower outer case (base) patterned by plating and made of resin molding
Further, by directly mounting the sensor chip and the electronic components, the HIC substrate and the case with a built-in substrate, which have been conventionally required, are not required, and the size and cost can be reduced.

Further, a shield pattern is formed by plating on the inner surface of the lower outer case, and the sensor chip and the I
Since C is mounted, the parasitic capacitance and the external electric field are shielded, so that the parasitic capacitance and the external electric field are not affected,
Accurate pressure detection can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a semiconductor pressure sensor of the present invention.

FIG. 2 is a sectional view showing an embodiment of a conventional semiconductor pressure sensor.

[Explanation of symbols]

 1 Silicon Substrate 2 Diaphragm Part 3 Glass Substrate 4 Fixed Electrode 5 Cavity Part 6 Sensor Chip 8, 12 Through Hole 10 Lead Wire 11 Sealant 13 Cap Part 14, 29 Lead Terminal 16 Mold Package 18, 23 Conductor Pattern 19, 27 Pedestal 20 IC chip 21 Silicon gel

Claims (1)

[Claims] 1. A detection element portion having a silicon substrate having a diaphragm portion that is deformed by a pressure to be measured, an upper outer case having a pressure inflow through hole, a wiring pattern formed by plating, and a region to which a metal is adhered is formed. In a semiconductor pressure sensor including a lower outer case and an electronic component, an IC chip having the detection element section and a detection circuit for detecting the detection element section formed as an IC is attached to the lower outer case by metal. A semiconductor pressure sensor characterized by being installed in an area.