JPH01187426A - Manufacture of semiconductor pressure sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a semiconductor pressure sensor that converts pressure into an electrical signal by utilizing the piezoresistance effect of a semiconductor single crystal such as silicon, and particularly relates to The present invention relates to a method for manufacturing a semiconductor pressure sensor that improves the bonding method for bonding a sensor chip, a glass substrate, and a metal support.

<Prior art> Fig. 4 shows the structure of a conventional semiconductor pressure sensor. f
It is an r-plane view.

Reference numeral 10 denotes a sensor chip made of n-type silicon single crystal, which has a concave portion 11, and further includes a strain-generating portion 12 in which the thickness of the single crystal is reduced due to the formation of the concave portion 11, and a fixed portion 1 around it.
3.

The strain-generating part 12 is a (100) plane of a single crystal, and on the strain-generating part 12, for example, a shear type gauge 14 is placed near the boundary with the fixed part 13 in the <100> direction of the crystal axis passing through the center of the single crystal. is formed as a P-type.

The shear type gauge 14 has a pair of power supply ends in its longitudinal direction, to which a power supply voltage is applied, and a pair of output ends formed approximately at the center in the longitudinal direction from which an output voltage is obtained.

The sensor chip 10 has a fixing portion 13 formed on a glass substrate 1 such as Pyrex glass having a pressure guiding hole 15 in the center.
6, and this glass substrate 16 has a pressure guiding hole 17 in the center.
It is fixed to a metal support stand 18 with a holder.

In the above configuration, when the measurement pressure P is applied to the strain-generating portion 12, a shear stress τ is generated in the shear type gauge 14, and a corresponding output voltage is obtained at the output end.

By the way, such a sensor chip 10 and a glass substrate 16
When attempting to realize a semiconductor pressure sensor by anodic bonding between the metal support bases 18, the sensor chip 10 is connected to the glass substrate 16 as shown in FIG.
1 to maintain a positive potential, and a metal support 18 to the glass substrate 16 is held to a positive potential by a power source E2 to perform anodic bonding.

<Problems to be Solved by the Invention> However, in such a conventional manufacturing method of a semiconductor pressure sensor, the negative potential sides of the power supplies E1 and E2 are connected to the glass substrate 16.
The voltage must be applied to the electrode 19 provided on the side surface of the electrode. When voltage is applied in this manner, the electric field within the glass substrate 16 becomes uneven locally, which causes a problem in that the bonding strength between the sensor chip 10 and the support base 18 with respect to the glass substrate 16 is uneven. .

<Means for Solving the Problems> In order to solve the above problems, the present invention forms a conductive silicon film on one side of a first glass substrate, and what is the first glass substrate of this conductive silicon film? A second glass substrate is placed on the opposite side, and the second glass substrate is placed at a negative potential and the conductive silicon film is placed at a positive potential for anodic bonding. Next, a sensor chip on which a diaphragm having a piezoresistive element is formed and a metal Support stands are placed on both sides of the first and second glass substrates, and these glass substrates are held at a positive potential and anodic bonded to the conductive silicon film.

Function> A conductive silicon film is formed on one side of the first glass substrate, a second glass substrate is anodically bonded onto this conductive silicon film, and sensors are placed on each of the first and second glass substrates. By arranging and anodic bonding the chip and the metal support, a uniform electric field is formed in the first and second glass substrates, and as a result, the bonding strength between the sensor chip and the support on both sides of the glass substrate is increased. Stably obtained.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

Note that parts having the same functions as those in the prior art are given the same symbols, and the explanation thereof will be omitted as appropriate.

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

20 is a polydinocon film, and this polysilicon film 20
It is doped with phosphorus to make it conductive. 21
．． 22 are glass substrates bonded to the polysilicon film 20, respectively.

A fixing portion 13 of the sensor chip 10 on which a shear gauge 14 is formed is bonded onto the glass substrate 21 .

A metal support 18 having a thermal expansion coefficient close to that of the glass substrates 21 and 22 is bonded to the bottom of the glass substrate 22. The other end of the support base 18 is fixed to, for example, a pressure vessel.

FIG. 2 is a process diagram showing a joining process for joining the semiconductor pressure sensor shown in FIG. 1.

In the process of FIG. 2(a), a wafer-shaped glass substrate 22W
This figure shows a step of forming a wafer-shaped conductive polysilicon film 20W on the film by sputtering.

In the process of FIG. 2(b), the polysilicon film 20 is
A wafer-shaped glass substrate 21W is placed on the glass substrate 22W on which W is formed, and a voltage is applied between the polysilicon WA 20W and the glass substrate 21W with the polysilicon M2OW side at a positive potential to form the polysilicon film 20W. Anodic bonding is performed with the glass substrate 21W.

In the step of FIG. 2(C), for example, sensor chips IOA, IOB, and 10C are mounted on the glass substrate 21W, and support stands 18A, 18B, and 18C are mounted on the glass substrate 22W.
The sensor chips 10A, 10b, 10C and the support bases 18A, 1 are arranged on the sides corresponding to the sensor chips 10A, IOB, 10C, respectively, and then the sensor chips 10A, 10b, 10C and the support stands 18A, 1 are placed on the polysilicon film 20W.
Power supply E4, so that 8B and 18C have positive potential, respectively.
By applying E5, these are anodic-bonded all at once.

Thereafter, the wafer-shaped glass substrate is diced to produce the semiconductor pressure sensor shown in FIG.

The bonding process shown in FIG. 3 is almost the same as that shown in FIG. 1, but as shown in FIG. The difference is that the silicon substrate 23 is anodically bonded.

Anodic bonding is performed under predetermined environmental conditions using a power source E6 with the silicon substrate 23W side as a positive electrode and the glass substrate 22W side as a negative electrode.

3(B) and 3(C) correspond to FIGS. 2(B) and 2(C), except that the silicon substrate 23V is different.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, a silicon chip and a support stand are arranged on the front and back sides of a glass substrate with a conductive silicon film interposed therebetween. Since anodic bonding is used, the electric field distribution becomes -like, and stable bonding strength can be obtained on both sides of the glass substrate. Furthermore, since the electric field distribution is uniform, a plurality of sensor chips and the support base can be bonded at the same time, making mass production possible and reducing costs. In addition, by using this type of bonding method, glass and metal can be directly bonded, and there is no need to interpose an intermediate wheel with a different coefficient of thermal expansion between them, so there is no output drift or zero. Offset can also be effectively suppressed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a semiconductor pressure sensor manufactured according to the present invention, FIG. 2 is a process diagram showing a joining method for joining the semiconductor pressure sensor shown in FIG. 1, and FIG. 3 is a joining method shown in FIG. 2. A process diagram showing a bonding force -7= method different from the method, Fig. 4 is a vertical cross-sectional view showing the configuration of a conventional semiconductor pressure sensor, and Fig. 5 shows a bonding method for assembling the semiconductor pressure sensor shown in Fig. 4. FIG. 10, IOA, IOB, IOC...sensor chip, 1
2... Strain generating part, 13... Fixed part, 14... Shear type gauge, 16.21.22.21W, 22W... Glass substrate, 18... Support stand, 20.20W...・Polysilicon film. Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] forming a conductive silicon film on one side of the first glass substrate;
A second glass substrate is placed on the opposite side of the conductive silicon film to the first glass substrate, and anodic bonding is performed with the second glass substrate at a negative potential and the conductive silicon film at a positive potential;
Next, a sensor chip on which a diaphragm having a piezoresistive element is formed and a metal support are placed on both sides of the first and second glass substrates, and these glass substrates are placed against the conductive silicon film. A method for manufacturing a semiconductor pressure sensor, characterized in that it is held at a positive potential and anodic bonded.