JPH06201504A - Manufacture of semiconductor dynamical amount sensor - Google Patents

Abstract

PURPOSE:To reduce the cost and to make the quality common by manufacturing semiconductor sensors of the same characteristics by a batch processing. CONSTITUTION:A sensor cover 102 is prepared by forming a recession 24 in a substrate and by forming a P-type diffused region 21 for an upper electrode on the surface wherein the recession 24 is formed. A sensor main body 100 is prepared by forming a P-type diffused layer 13 for wiring and a P-type diffused layer 12 for a lower electrode separately in the surface of a substrate 11 and by forming an oxide film 14 selectively on the upper side of these layers. Next, the sensor cover 102 and the sensor main body 100 are opposed to each other and bonded by a polysilicon layer 17, and after bonding, chip split is conducted for each sensor as a unit. By this method, a manufacturing process is simplified and thus the cost can be reduced, while it is made possible, by using polysilicon, to make the adhesion strong and the quality common.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor mechanical quantity sensor for measuring a mechanical quantity, for example, a pressure by changing a capacitance of a capacitor.

[0002]

2. Description of the Related Art As a pressure sensor of this type, for example, FIG.
The one shown in FIG.
-63826). In FIG. 4, the through hole 3 is formed in the upper surface of the metallic stem 2 integrated with the pressure introducing pipe 1.
The silicon pedestal 3 having a is bonded via the adhesive layer 4a, and the silicon diaphragm 5 cut out from the wafer is fixed to the upper surface of the silicon pedestal 3 via the adhesive layer 4b. A bending portion 5a that bends due to pressure is formed in the central portion of the silicon diaphragm 5, and a semiconductor strain gauge 6 that provides a resistance change corresponding to the bending amount is provided at a predetermined position on the bending portion 5a. . Further, a lead pin 7 is provided through the stem 2 in a hermetically sealed and insulated state by a hermetic seal 8, and the strain gauge 6 is connected via a bonding wire 9 and a lead pin 7. Is connected to an external circuit (not shown). Further, a metal cap 10 having a vent hole 10a on the top is connected to the stem 2 by electric discharge machining, soldering, etc., and the vent hole 10a is sealed with a solder 11 in a vacuum chamber to form a vacuum reference pressure chamber 12. obtain.
As described above, the absolute pressure sensor having the vacuum pressure as the reference pressure is manufactured.

When pressure is introduced into such a pressure sensor through the pipe 1, the bending portion 5a of the silicon diaphragm 5 bends in accordance with the pressure difference between the upper and lower sides, and the strain gauge 6 corresponding to the amount of the bending bends. The change in resistance value is input as an electric signal to an external circuit (not shown) via the bonding wire 9 and the lead pin 7, whereby the pressure is measured.

[0004]

However, in the above-mentioned pressure sensor, the diaphragm 5 formed on the semiconductor wafer is divided into chips and then the package of the package is formed.
Each chip is vacuum-mounted using a die or the like. That is,
Vent hole 10a provided in cap 10 after chip division
There is a problem in that the manufacturing cost is high because the vacuum reference pressure chamber 10 is formed by sealing the inside of the vacuum chamber with solder or the like in the vacuum chamber. Further, since the diaphragm 5 is manufactured by dividing the wafer into chips, the quality can be made common. On the other hand, when manufacturing the pressure sensor by vacuum-mounting the diaphragm 5, for example, the mounting position of the pipe 1 for pressure introduction, etc. Therefore, there is a problem in that the characteristics of the manufactured pressure sensor vary.

An object of the present invention is to provide a method for manufacturing a semiconductor dynamical quantity sensor in which cost reduction and quality standardization are achieved by manufacturing semiconductor sensors having the same characteristics by batch processing.

[0006]

[Means for Solving the Problems] FIGS.
The present invention will be described with reference to the first silicon substrate 20.
Forming a plurality of recesses 24 in each of the recesses 24 and forming the first electrode 21 from the inner peripheral surface to the peripheral edge of each recess 24; and forming the second electrodes 12 insulated from each other on the surface of the second silicon substrate 11. A region including the wiring layer 13 is formed in the same arrangement as the recess 24 of the first silicon substrate 20, an insulating layer 14 is formed on the upper surface of each region, and the insulating layer 14 is connected to the wiring layer 13. A first opening portion 14b and a second opening portion 14c for connecting the second electrode 12 and a third opening portion 14a for connecting to the second electrode 12, respectively;
a step of providing a first wiring part 16 connected to the wiring layer 13 in b and a second wiring part 15 connected to the second electrode 12 in the third opening 14a; Forming a polysilicon layer 17 having substantially the same shape as that on the insulating layer 14 so that a part of the polysilicon layer 17 is electrically connected to the wiring layer 13 through the second opening 14c; the first silicon substrate 20 and the second silicon substrate 20. Of the first recessed portion 24 and the polysilicon layer 17 are thermally bonded together in a predetermined pressure atmosphere, and the first silicon substrate 20 and the second bonded silicon substrate 11 are bonded together.
And the step of dividing the silicon substrate 11 of FIG.

[0007]

The first silicon substrate 20 on which the first electrode 21 is formed and the second silicon substrate 11 on which the second electrode 12 is formed are opposed to each other, and a plurality of silicon substrates formed on the first silicon substrate 20 are arranged. And the polysilicon layer 17 having substantially the same shape as the peripheral edge of the recess 24 formed in the second silicon substrate 11 are thermally bonded in a predetermined pressure atmosphere, and then both silicon substrates 11 and 20 are chip-by-chip unit. Since it is divided, a plurality of semiconductor dynamic quantity sensors can be simultaneously manufactured by thermally adhering both silicon substrates 11 and 20 in a predetermined pressure atmosphere before the division, and the vacuum mounting work which was conventionally indispensable becomes unnecessary. The process can be extremely simplified and an inexpensive semiconductor dynamic quantity sensor can be obtained. Further, since the polysilicon layer 17 is used for adhesion, it is possible to strengthen the adhesive force and standardize the quality.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a semiconductor pressure sensor 100 according to the present invention includes a sensor body 1 including a semiconductor substrate.
01 and a sensor cover 102 that is bonded to the upper surface of the sensor cover 102 to form a reference pressure chamber RR and is composed of a semiconductor substrate. The P type diffusion layer 12 for the lower electrode of the sensor body 101 and the upper electrode of the cover body 102 are provided. The P-type diffusion layer 21 and the reference pressure chamber R
They face each other across R and form a capacitor.

The sensor body 101 is an N type silicon substrate 1.
1, a wiring P-type diffusion layer 13 of the lower electrode P-type diffusion layer 12 and the upper electrode P-type diffusion layer 21, and an oxide film 14 formed on the surface of the N-type silicon substrate 11. . The end of the lower electrode P-type diffusion layer 12 is connected to the wiring 15 via the contact hole 14a, and the end of the wiring P-type diffusion layer 13 is also connected to the wiring 16 via the contact hole 14b. ing. These wirings 15 and 16 are used as signal lines for capacitors. A cover body 102 is provided on the oxide film 14 via a polysilicon layer 17.

The cover body 102 has an upper electrode P-type diffusion layer 21, a buried P-type diffusion layer 22, an N-type epitaxial layer 23, and a reference pressure chamber recess 2 on an N-type semiconductor substrate, as will be described later.
After forming 4, the N-type semiconductor substrate is removed by etching. Here, the N-type epitaxial layer 23 functions as a bending portion. The upper electrode P-type diffusion layer 21 is connected to the wiring P-type diffusion layer 13 via the polysilicon 17 provided in the contact hole 14c of the oxide film 14. The upper electrode P-type diffusion layer 21 is insulated from the lower electrode P-type diffusion layer 12 through the oxide film 14.

When such a pressure sensor 100 is arranged in a pressure atmosphere, the bending portion 25 of the cover body 102 bends in accordance with the pressure difference between this atmosphere pressure and the reference pressure in the reference pressure chamber RR, and as a result, the upper portion The electrostatic capacitance between the electrode P-type diffusion layer 21 and the lower electrode P-type diffusion layer 12 changes.
The atmospheric pressure is detected by detecting this change in capacitance. That is, the pressure sensor 100 having the above configuration
Can be made by bonding two substrates together in a vacuum before chip division, eliminating the need for vacuum mounting work for each chip, which was indispensable in the past, and greatly simplifying the manufacturing process and making it inexpensive. A semiconductor dynamic quantity sensor is obtained.

Next, the manufacturing process of this semiconductor dynamical quantity sensor will be described with reference to FIGS. Although FIGS. 2 and 3 show the structure of one semiconductor pressure sensor, a plurality of semiconductor pressure sensors having the structures of FIGS. 2 and 3 are actually formed on the semiconductor substrate. (A) As shown in FIG. 2A, a cover in which a P-type diffusion layer 22 is embedded and an N-type epitaxial layer 23 is formed.
An oxide film 31 is formed on the entire lower surface of the main body substrate 20 (made of, for example, an N-type silicon substrate having a plane orientation (100)) by thermal oxidation or CVD, and then the oxide films 31 at both ends are removed by photoetching or the like. (B) As shown in FIG. 2B, anisotropic etching is performed with an anisotropic etching solution such as hydrazine using the oxide film 31 as a mask, and the lower portions of both ends of the substrate 20 are removed to a predetermined depth. To form. (C) After removing the oxide film 31 on the lower surface of the convex portion 20a, the oxide film 32 is formed again on the entire lower surface of the substrate 20 by the above method, and the oxide film 32 at the center of the convex portion 20a is removed by photoetching (see FIG. 2 (c)). (D) As shown in FIG. 2D, the substrate 2 is etched with an anisotropic etching solution such as hydrazine using the oxide film 32 as a mask.
The center of the convex portion 20a of 0 is removed to a predetermined depth to form the concave portion 20b.
(24) is formed. This recess 20b is the reference pressure chamber RR.
To form. (E) The P-type diffusion layer 21 for the upper electrode is formed on the entire lower surface of the protrusion 20a by thermal diffusion of boron or ion implantation and annealing (FIG. 2 (e)).

(F) As shown in FIG. 3A, another substrate 11 made of N-type silicon having a plane orientation (100), for example.
The lower electrode P-type diffusion layer 12 and the wiring P are formed on the upper surface of the substrate by thermal diffusion of boron or ion implantation and annealing.
The type diffusion layer 13 is selectively formed. (G) As shown in FIG. 3B, after forming the oxide film 14 on the entire upper surface of the substrate 11, contact hole regions 14b and 14c for connecting upper electrodes and a contact hole region 14a for connecting lower electrodes are formed. The oxide film is removed by photoetching.

(H) As shown in FIG. 3 (c), the recess 2
A polysilicon layer 17 having substantially the same shape as the peripheral edge of 0b is formed in the contact hole region 14c and connected to the wiring P-type diffusion layer 13, and is formed on the oxide film 14 to form the lower electrode P-type diffusion layer 12. Insulate. Further, wirings 15 and 16 are formed in the contact hole regions 14a and 14b, respectively. Next, after the substrates 20 and 11 are both subjected to hydrophilic treatment, the substrate 11 and the substrate 20 are opposed to each other, and the polysilicon layer 17 of the substrate 11 and the peripheral edge of the recess 20b of the substrate 20 are provided in a predetermined clean environment. Contact and heat under pressure. As a result, the substrate 20 and the substrate 11 are adhered, and the recess 20b is formed.
Thus, the reference pressure chamber RR is formed. The above-mentioned predetermined pressure becomes the reference pressure in the reference pressure chamber RR, and this pressure is set to an appropriate value in advance. Further, the temperature at the time of heating is also set in advance to an appropriate value in consideration of adhesion strength and the like.

(I) As shown in FIG. 3 (d), the substrate 2
0 is etched to remove the regions other than the regions surrounded by the P-type diffusion layers 21 and 22 to form the cover body 102. Since the P-type diffusion layers 21 and 22 prevent excessive etching, the shape of the cover body 102 can be made uniform, and a pressure sensor having stable sensor characteristics can be obtained. (J) Finally, as shown in FIG.
The semiconductor pressure sensor shown in (d) is divided into chips.

In the above manufacturing process, each substrate 11, 20
The polysilicon used to bond the substrates together is the substrate 11, 20.
It has good adhesiveness to silicon, which is the material of, and a strong adhesive force can be obtained by heating. Also, the polysilicon layer 1
7 is formed by vapor deposition or the like, and its thickness can be arbitrarily controlled. Therefore, the distance between the upper electrode P-type diffusion layer 21 and the lower electrode P-type diffusion layer 12 can be made common to each pressure sensor. it can. Further, since polysilicon has excellent conductivity, the P-type diffusion layer 21 for the upper electrode and the P-type diffusion layer 22 for the wiring are formed.
And can be made to have substantially the same potential. Due to the characteristics of polysilicon as described above, the characteristics of each pressure sensor obtained by dividing a chip after manufacturing a plurality of pressure sensors having the structure of FIG. 1 on a semiconductor substrate become uniform. Further, according to the manufacturing method of the present invention, both the wiring 15 for the lower electrode and the wiring 16 for the upper electrode can be provided on the surface of the substrate 11, so that bonding or the like becomes easy.

Before the protrusion 20a and the substrate 11 are bonded together, the substrate 20 may be thinned by etching, mechanical polishing or the like within a range where mechanical strength is maintained.

The semiconductor mechanical quantity sensor manufactured by the manufacturing method of the above embodiment can be used not only as the pressure sensor described above but also as an acceleration sensor for detecting acceleration.

In the embodiment constructed as described above,
The substrate 20 is the first silicon substrate, the recess 24 is the recess,
The upper electrode P-type diffusion layer 21 is the first electrode, the substrate 11 is the second silicon substrate, the lower electrode P-type diffusion layer 12 is the second electrode, and the wiring P-type diffusion layer 13 is the wiring layer. First, the oxide film 14 serves as an insulating layer, the contact hole 14b serves as the first opening, the contact hole 14c serves as the second opening, the contact hole 14a serves as the third opening, and the wiring 16 serves as the first opening.
, The wiring 15 corresponds to the second wiring portion, and the polysilicon layer 17 corresponds to the polysilicon layer.

[0021]

According to the present invention, the first silicon substrate on which the first electrode is formed and the second silicon substrate on which the second electrode is formed are opposed to each other in a predetermined pressure atmosphere. Since two or more semiconductor dynamic quantity sensors are bonded at the same time, it is possible to bond both substrates in a vacuum before dividing them into chips, which eliminates the need for vacuum mounting for each chip, which was indispensable in the past. Thus, the manufacturing process can be extremely simplified, and an inexpensive semiconductor dynamic quantity sensor can be provided. Moreover, since both silicon substrates are adhered by the polysilicon layer, a strong adhesive force can be obtained. Furthermore, since the thickness of the polysilicon layer can be controlled arbitrarily, the distance between both silicon substrates can be made common to each semiconductor dynamical quantity sensor. Furthermore, since the polysilicon layer has excellent conductivity, the voltages of the first electrode and the second electrode can be accurately detected, the detection accuracy of the sensor is improved, and the first and second electrodes are formed on the surface of the second silicon substrate. Since the first wiring portion and the second wiring portion for taking out the second electrode can be formed, bonding and the like can be easily performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor dynamic quantity sensor manufactured by a method for manufacturing a semiconductor dynamic quantity sensor according to the present invention.

2A to 2C are views for sequentially explaining a manufacturing process of the semiconductor dynamical amount sensor shown in FIG.

FIG. 3 is a diagram for sequentially explaining the manufacturing process subsequent to FIG.

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

[Explanation of symbols]

 11 N-type semiconductor substrate 12 P-type diffusion layer for lower electrode 13 P-type diffusion layer for wiring 14 Oxide film 14a to 14c Contact holes 15, 16 Wiring 17 Polysilicon layer 21 P-type diffusion layer for upper electrode 22 Embedded P-type Diffusion layer 24 Recessed portion 25 Bent portion 101 Sensor body 102 Sensor cover RR Reference pressure chamber

Claims (1)

[Claims] 1. A step of forming a plurality of recesses in a first silicon substrate and forming a first electrode from an inner peripheral surface to a peripheral edge of each recess, and a surface of the second silicon substrate insulated from each other. A region including a second electrode and a wiring layer is formed in the same arrangement as the recess of the first silicon substrate, an insulating layer is formed on the upper surface of each region, and the insulating layer is connected to the wiring layer. A first opening and a second opening for connecting the second electrode and a third opening for connecting to the second electrode, and connecting the wiring layer to the first opening. And a second wiring part connected to the second electrode in the third opening, and a polysilicon layer having substantially the same shape as the peripheral edge of the recess, The insulating layer is formed so that a part thereof is electrically connected to the wiring layer through the second opening. A step of forming the first silicon substrate and a step of causing the first silicon substrate and the second silicon substrate to face each other, and thermally bonding the peripheral edge of the recess and the polysilicon layer in a predetermined pressure atmosphere; And a step of dividing the first silicon substrate and the second silicon substrate in units of the region.