JPH07318445A - Capacitance type pressure sensor and manufacture thereof - Google Patents

Abstract

PURPOSE:To stably manufacture a pressure sensor with an excellent yield so that dispersion of sensor sensitivity can be restrained within a narrow range by uniformizing a thickness of a thin part within a narrow range. CONSTITUTION:An insulating film 2 is formed on a surface of a silicon substrate 1, and a silicon layer 3 is formed on it. A lower electrode 4, a signal processing circuit part 5 and connecting wiring 6 are formed on the silicon layer 3. The silicon substrate 1 is selectively etched, and a thin part 7 and a thick part 8 are formed. Recessed parts 12 and 13 are formed on an upper glass plate 11, and an upper electrode 14 is formed in the recessed part 12. The upper glass plate 11 and the silicon layer 3 are stuck together by a positive electrode joining method. The thin part 7 is composed of the insulating film 2 and the silicon layer 3, and constitutes a pressure sensitive part. Since a thickness of the thin part 7 can be determined by polishing the silicon layer, a thickness of the thin part is restrained within a narrow dispesion range, and sensor sensitivity can be uniformized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type pressure sensor using a silicon substrate and a manufacturing method thereof.

[0002]

2. Description of the Related Art A pressure sensor using silicon is a pressure-sensitive diaphragm obtained by etching a part of a silicon substrate.
A glass plate provided with an electrode is provided in a portion facing the pressure-sensitive portion, a capacitor is formed between the diaphragm and the electrode, and a change in capacitance due to a pressure change is detected.

[0003] Conventional pressure sensors, and two pressure P ₀ when none of the two pressure P ₀ and P ₁ is not a fixed value P
A relative pressure sensor that measures the differential pressure of ₁ and two pressures P
Two pressures P ₀ when _one of ₀ and P ₁ is a fixed value
There are two types of absolute pressure sensor that measures the pressure difference P ₁ and.

FIG. 6 is a sectional view of an example of a conventional capacitance type pressure sensor.

For the diaphragm 51 of this pressure sensor, a single-conductivity type (p-type or n-type) single-crystal silicon substrate is etched to form a thin portion 52 and a thick portion 53 on one surface,
In the structure in which the concave portion 54 is formed on the other surface to form a pressure sensitive portion, the lower electrode 55 is provided in the concave portion 54, and the signal processing circuit portion 56 is provided next to the pressure sensitive portion including the thin portion 52 and the thick portion 53. Has become. The signal processing circuit unit 56 is configured by providing an element region 58 in a well 57 of a conductivity type (n type or p type) opposite to that of a silicon substrate, and connecting an electrode 59 to the element region 58.

On the upper glass plate 61, an upper electrode 62 and a connecting wiring (not shown) for connecting the upper electrode 62 to the signal processing circuit section 56 are formed in a region of the diaphragm 51 facing the lower electrode 55, and a signal is provided. A concave portion 63 is formed in a region facing the processing circuit portion 56, and a space for protecting the signal processing circuit portion 56 from being damaged is formed.

An upper glass plate 61 is placed on the diaphragm 51.
Then, the lower electrode 55 and the upper electrode 62 are aligned with each other, and they are bonded by an anodic bonding method in which they are heated to about 400 ° C. and a DC voltage of 600 to 1000 V is applied.

By bonding the diaphragm 51 and the upper glass plate 61 together, a sealed space 64 is formed between the recess 54 of the diaphragm 51 and the upper glass plate 61. The pressure in this space 64 is P ₀ . The pressure P ₀ is a constant value and serves as a reference value. If the external pressure is P ₁ ,
The pressure sensor, the pressure difference to a reference value of pressure P ₀ (P
₁₋ P ₀ ) is detected. The signal processing circuit unit 56 calculates the absolute pressure from this value. Space 64 in the upper glass plate 61
When a pressure P ₂ of another gas is introduced into the space 64 to measure the pressure difference (P ₁ −P ₂ ), this pressure sensor measures the relative pressure (P ₁ −P ₂ ) to the pressure P ₂ . P ₂ )
Will be measured.

7A to 7C are sectional views showing the method of manufacturing the diaphragm of FIG. 6 in order of steps for explaining the method.

First, as shown in FIG. 7 (a), a single crystal having a major surface whose crystal orientation is [100] is of one conductivity type (p).
Type or n-type) silicon substrate 71 is provided with a resist mask 72 such as SiO ₂ and an opening is formed in the resist mask 72 in a region where a lower electrode is formed. Type or p-type) impurities are introduced by ion implantation or diffusion to form the opposite conductivity type region 73.

Next, as shown in FIG. 7B, the resist mask 72 is removed, a new resist mask is provided, an opening is formed, and an impurity is introduced into the well 57 of the opposite conductivity type by a usual method. Conductive element region 58, electrode 5
9. An insulating film 74 is formed.

Next, as shown in FIG. 7C, a resist mask 75 is provided on the surface of the silicon substrate 71 to protect it.
Resist masks 76 and 77 having different etching resistances are provided on the back surface of the silicon substrate 71. SiO ₂ and Si ₃ N ₄ are suitable as materials for such a resist mask.
An opening is formed in the resist mask 77 where the thin portion is to be formed, and the resist mask 76 is etched leaving the resist mask 76 where the thick portion 53 is to be formed to form the opening. To expose the back surface of the silicon substrate 71. TMAH the silicon substrate 71 through the opening
(Tetramethylammonium hydroxide, (C
H ₃ ) ₄ NOH) and the like are anisotropically etched to form the recess 78.
To form. The depth of the concave portion 78 is the same as the thin portion 52 and the thick portion 5
The difference in thickness from 3 is used.

Next, as shown in FIG. 7D, the resist mask 76 in the opening of the resist mask 77 is removed, and the silicon substrate 71 is etched by TMAH. This etching is performed until the thin portion 52 has a predetermined thickness. At this time, the thick portion 53 is also etched, and the thick portion 53
The lower surface of the silicon substrate 71 is recessed from the lower surface of the silicon substrate 71.

Next, as shown in FIG. 7E, the lower surface of the silicon substrate 71 and the surfaces of the resist masks 76 and 77 are covered with a resist mask 79 such as photoresist to form the recess 54.
An opening is formed in the resist mask 75 above the region where the mask is to be formed. The silicon substrate 71 is etched through this opening to form the recess 54. At this time, the opposite conductivity type region 73 is also etched to form the lower electrode 55.

Next, as shown in FIG. 7F, the resist masks 75 to 77 and 79 are removed to obtain the diaphragm 51.

FIGS. 8A to 8C are sectional views showing the method of manufacturing the upper glass plate of FIG. 6 in order of steps for explaining the method.

First, as shown in FIG. 8A, a resist mask 8 is formed on both surfaces of the upper glass plate 61 with photoresist or the like.
1, 82, and an opening 83 is provided in the resist mask 81. The upper glass plate 61 is etched through the opening 83 with a hydrofluoric acid-based etching solution to form a recess 63.

Next, as shown in FIG. 8B, the resist mask 82 is removed, a new resist mask 84 is provided, and the resist mask 84 in the region where the upper electrode 62 is formed is formed.
An opening 85 is formed in the.

Next, as shown in FIG. 8C, a metal film 86 is formed on the resist mask 84 by vapor deposition or sputtering.

Next, as shown in FIG. 8D, the resist mask 84 is removed together with the metal film 86 thereon. The metal film 86 at the opening 85 remains, and the upper electrode 47 is formed. In this way, the upper glass plate 61 of FIG. 6 is obtained.

Diaphragm 5 manufactured in this way
1 and the upper glass plate 61 are overlapped with each other, and the lower electrode 55 and the upper electrode 62 of the diaphragm 51 are aligned with each other, and about 40
The pressure sensor shown in FIG. 6 is manufactured by heating at 0 ° C. and bonding by an anodic bonding method in which a DC voltage of 600 to 1000 V is applied.

[0022]

In the manufacture of the conventional pressure sensor described above, in order to keep the sensitivity of the pressure sensor within the range of narrow variation, the thickness of the thin portion which is the pressure sensitive portion of the diaphragm varies widely. Must be within the range of. In the past, the thickness of the thin portion was controlled by controlling the composition of the etching solution, the temperature, and the etching time. However, the thickness of the thin portion has a variation of about ± 3 μm. Was very difficult. Therefore, there is a problem that the yield of the pressure sensor having the sensitivity within a narrow range is low and the cost is high.

An object of the present invention is to have a structure in which it is easy to make the thickness of the thin portion within a narrow range of variation and to easily set the sensitivity of the sensor within a narrow range of variation.
An object of the present invention is to provide an electrostatic capacitance type pressure sensor and a manufacturing method thereof that can stably manufacture products with uniform sensitivity with good yield.

[0024]

A capacitance type pressure sensor according to the present invention comprises a single conductivity type single crystal silicon layer provided on a silicon substrate via an insulating film and a surface of the silicon layer. A diaphragm having a lower electrode provided and a thin portion formed by selectively removing a region of the silicon substrate facing the lower electrode, and a diaphragm attached to an upper surface of the diaphragm and facing the lower electrode with a space therebetween. An upper glass plate having an upper electrode, and a signal processing circuit unit provided on the surface of the silicon layer for calculating a pressure value by receiving signals from the lower electrode and the upper electrode are provided.

The present invention is characterized in that the thin portion comprises the insulating film and the silicon layer.

The present invention is characterized in that the thin portion is composed of only the silicon layer.

The present invention is characterized in that a thick portion which is formed of a part of the silicon substrate and is thicker than the thin portion is provided in a central portion of the thin portion.

The present invention is characterized in that the thick portion is in contact with the silicon layer through the insulating film.

According to the present invention, a part of the silicon substrate is selectively removed by insulation to form an island of silicon, an opening formed by selectively removing the insulating film in contact with the island, and the signal through the opening. It is characterized by including a connection wiring for connecting the input / output section of the processing circuit section and the island.

The method of manufacturing a capacitance type pressure sensor according to the present invention comprises: (A) a step of forming an insulating film of a predetermined thickness on the surface of a silicon substrate, and a single crystal of one conductivity type on the insulating film. A step of providing the silicon layer, a step of adjusting the silicon layer to a predetermined thickness, and a step of forming a lower electrode and a signal processing circuit section connected to the lower electrode at a predetermined position on the surface of the silicon layer. A step of forming a thin portion by selectively removing a region of the silicon substrate facing the lower electrode, and (B) providing an etching resistant resist mask on both surfaces of the glass plate, A step of forming an opening in a resist mask in a region facing the lower electrode and the signal processing circuit section; and etching the glass through the opening to expose the lower electrode and the signal processing circuit section. Forming a recess in the fit region,
An upper part including a step of removing the resist mask, a step of forming an upper electrode in a recess facing the lower electrode, and a step of forming a connection wiring for connecting the upper electrode to the signal processing circuit section. Glass plate forming step, (C) The upper glass plate is aligned and bonded on the upper surface of the diaphragm so that the lower electrode and the upper electrode face each other, and at the same time, the connection wiring is connected to the signal processing circuit unit. And a step of performing.

According to the present invention, the step of forming the thin portion includes
It is characterized in that it is a step of selectively removing and forming only the silicon substrate.

According to the present invention, the step of forming the thin portion includes
It is characterized in that it is a step of selectively removing and forming the silicon substrate and the insulating film.

The present invention is characterized by including a step of selectively removing a part of the silicon substrate at a central portion of the thin portion to form a thick portion.

According to the present invention, a portion of the periphery of the silicon substrate is selectively removed until reaching the insulating film to form an island of silicon that is insulated and separated, and the insulating film in contact with the island is selectively removed. The method may further include connecting an input / output unit of the signal processing circuit unit to the island.

[0035]

In the present invention, the silicon substrate and the silicon layer are bonded together via the insulating film, the lower electrode is provided on the surface of the silicon layer, and the region of the silicon substrate facing the lower electrode is selectively removed to form a thin portion. This constitutes the diaphragm. Then, an upper glass plate having an upper electrode facing the lower electrode of the diaphragm is joined onto the diaphragm to form a capacitance type pressure sensor. The thickness of the thin portion that becomes the pressure sensitive portion is determined by the thickness of the silicon layer and the insulating film. Although the thickness of the silicon layer is adjusted by polishing, the polishing of the silicon layer can be controlled with considerably high accuracy, and the thickness of the silicon layer is set within a target range within a narrow variation. Further, the thickness of the insulating film can be controlled within a range of variation narrower than that of the silicon layer. Therefore, the thickness of the thin portion can be kept within a range of variation that is narrower by one digit than the conventional one.

The thin portion is formed by selectively etching a silicon substrate, and at that time, the insulating film functions as an etch stopper. Therefore, if etching is performed so that the insulating film is exposed, the thickness of the thin portion is determined by the thickness of the silicon layer and the insulating film, and the thickness of the thin portion may vary due to insufficient etching or excessive etching. Absent.

In order to increase the sensitivity of the pressure sensor, it is preferable that the thin portion has a small thickness. Therefore, remove the insulating film,
The sensitivity of the pressure sensor can be increased by forming the thin portion only with the silicon layer to reduce the thickness of the thin portion. Since the insulating film functions as an etch stopper, the insulating film is removed after the selective etching of the silicon substrate is completed.

The pressure-sensitive portion of the pressure sensor can be composed of only the thin-walled portion, but when a large pressure is applied, the thin-walled portion bends in an arc shape and the upper electrode and the diaphragm are not parallel to each other. Capacity conversion becomes complicated. In order to prevent this and maintain parallelism between the upper electrode and the diaphragm, a thick portion is provided in the central portion of the thin portion. The thick part is usually thicker than the thin part and thinner than the silicon substrate,
The thickness may be the same as that of the silicon substrate.

Since the thick portion is formed by selectively etching a part of the silicon substrate, the thick portion is in contact with the silicon layer via the insulating film.

In the pressure sensor of this invention, the silicon substrate and the silicon layer are completely insulated by the insulating film, and all electric signals are taken out from the silicon layer. This shows that no matter where the silicon substrate is attached, the silicon layer is always insulated and is not affected by the place of attachment, which is a great advantage. However, when the pressure sensor is mounted on the printed circuit board, it is often the case that the silicon substrate of the pressure sensor is mounted on the wiring or land of the printed circuit board and the input / output signals of the pressure sensor are sent to the wiring of the printed circuit board. In such a case, if the input / output section of the signal processing circuit section of the pressure sensor is connected to the silicon substrate, the input / output signal of the pressure sensor can be sent by simply attaching the pressure sensor to the wiring or land of the printed circuit board. It is convenient because it can be fed to the wiring. In order to enable such a thing, a part of the silicon substrate is selectively removed to provide an island of insulation-isolated silicon, the insulating film in contact with this island is selectively removed, and an opening is formed. The input / output section of the signal processing circuit section and the island are connected by connection wiring.

In the method of manufacturing the pressure sensor of the present invention, the step of forming the insulating film to a predetermined thickness and the step of adjusting the silicon layer to a predetermined thickness are important. Although polishing is used for adjusting the thickness of the silicon layer, the thickness of the silicon layer can be brought to a target value with considerably high accuracy by polishing. The thickness of the insulating film can be controlled more than the control of the thickness of the silicon layer. Therefore, if the thin portion serving as the pressure sensitive portion is configured by the insulating film and the silicon layer, the thickness of the thin portion can be set within a narrow variation range, and a pressure sensor having uniform sensitivity characteristics can be provided. It can be stably manufactured with a high yield.

As described above, when the thin portion which becomes the pressure sensitive portion is composed of the insulating film and the silicon layer, the thin portion can be formed in the step of selectively removing only the silicon substrate.

In order to increase the sensitivity of the pressure sensor, it is preferable that the thin portion has a small thickness. Therefore, the thin portion is composed of only the silicon layer and the insulating film is removed. Since the insulating film functions as an etch stopper, the insulating film is removed after the selective etching of the silicon substrate is completed.

In order to prevent the thin portion from bending in an arc shape and to maintain the parallelism between the upper electrode and the diaphragm, the thick portion is provided in the central portion of the thin portion. The thick portion is a part of the silicon substrate. Is selectively removed to form a thick portion.

One of the advantages of the pressure sensor of the present invention is that the silicon layer in which the signal processing circuit portion is formed is completely insulated from the silicon substrate by the insulating film.
It may be convenient to connect the signal processing circuit section to the silicon substrate. In order to achieve this, a part of the silicon substrate is selectively removed until it reaches the insulating film to form an island of isolated silicon, and the insulating film in contact with this island is selectively removed to perform the signal processing circuit. Connect the input / output section of the section to the island.
Since the island is isolated from the rest of the silicon substrate, it does not electrically affect the rest of the silicon substrate.

[0046]

1 is a sectional view of a first embodiment of the present invention.

The silicon substrate 1 has a crystal orientation of [100].
It is composed of a single crystal silicon substrate having a main surface of. An insulating film 2 is formed on the surface of the silicon substrate 1, and a silicon layer 3 of one conductivity type is formed on the insulating film 2. Impurities of opposite conductivity type are diffused into the silicon layer 3 to a high concentration to form a lower electrode 4 having high conductivity, a signal processing circuit section 5 is formed in a region adjacent to the lower electrode 4, and connection wiring is formed by diffusion of impurities of opposite conductivity type. 6 is formed, and the lower electrode 4 and the signal processing circuit unit 5 are connected. The thin portion 7 and the thick portion 8 are formed by selectively etching the silicon substrate 1. The thin portion 7 is composed of the insulating film 2 and the silicon layer 3 and constitutes a pressure sensitive portion. This constitutes a diaphragm.

The thick-walled portion 8 is not always necessary, but has an effect of preventing the thin-walled portion 7 from bending in an arc shape when a large pressure is applied, and keeping the parallelism between the upper electrode 14 and the diaphragm stable. Therefore, it is better to provide the thick portion 8. The thick portion 8 is usually thicker than the thin portion 7 and thinner than the silicon substrate 1, but may be the same thickness as the silicon substrate 1.

The upper glass plate 11 has a thin portion 7 and a thick portion 8
A concave portion 12 is formed in a region facing the pressure-sensitive portion consisting of
The recess 13 is formed in a region facing the signal processing circuit unit 5, and the recess 12 is formed by forming an upper electrode 14 and a connection wiring (not shown) connecting the upper electrode 14 and the signal processing circuit unit 5. .

The upper glass plate 11 is placed on the upper surface of the silicon layer 3, the lower electrode 4 and the upper electrode 14 are aligned so that they face each other, and they are bonded by the anodic bonding method, and at the same time the connection wiring is connected to the signal processing circuit section 5. Connect to.

2A to 2D are cross-sectional views showing the method of manufacturing the diaphragm of FIG. 1 in order of steps for explaining the method.

First, as shown in FIG. 2 (a), the surface of a single crystal silicon substrate 1 having a main surface with a crystal orientation of [100] is thermally oxidized to a thickness of about 0.5-1 μm of SiO 2.
₂ insulating film 2 is provided. The insulating film 2 can be formed quite accurately and can be formed to a desired thickness with an accuracy of ± 0.01 μm or less. One conductivity type single crystal silicon plate 2
1 is separately prepared and placed on the insulating film 2 of the silicon substrate 1.

Next, as shown in FIG. 2B, a silicon plate 21 is superposed on the insulating film 2 and the temperature is about 1000 ° C. to 1 ° C.
The pieces are heated and bonded in a N ₂ atmosphere at 200 ° C. for about 1 hour. No particular pressure or voltage is applied between the silicon substrate 1 and the silicon plate 21.

Next, as shown in FIG. 2 (c), the silicon plate 21 is polished to prepare a thin silicon layer 3 having a thickness of about 15 to 25 μm. This adjustment is important because it determines the thickness of the thin portion 7. This polishing can be performed fairly accurately, and the desired thickness can be obtained with an accuracy within ± 0.5 μm. It is desirable that the silicon plate 21 be polished so that the sum of the thicknesses of the silicon layer 3 and the insulating film 2 is about 20 μm. A well 22, an element region 23, an insulating film 24 are formed by a usual method of providing a mask such as SiO _{2 on} the surface of the silicon layer 3, opening a window, and diffusing impurities.
The electrode 25 is formed to form the signal processing circuit unit 5. Similarly, a lower electrode 4 having a conductivity type opposite to that of the silicon layer 3 and a connection wiring 6 are formed.

Next, as shown in FIG. 2D, the surface of the silicon layer 3 is covered with a resist mask 26, and the back surface of the silicon substrate 1 is covered with a resist mask 2 having different etching resistance.
7 and 28 are provided. For example, if the resist mask 27
O ₂ and Si ₃ N ₄ are used for the resist mask 28. A window is opened in the resist mask 28 in the region where the thin portion 7 is formed,
Leaving the resist mask 27 in the region where the thick portion 8 is formed,
The resist mask 27 in the region where the thin portion 7 is formed is removed by etching.

Next, as shown in FIG. 2E, TMAH
(Tetramethylammonium hydroxide, (C
H ₃ ) ₄ NOH) is used for anisotropic etching to form the recess 29.
To form. TMAH etches silicon with little etching of SiO ₂ and is therefore superior to KOH for etching silicon when using SiO ₂ as a mask.

Next, as shown in FIG. 2 (f), the thick portion 8
The resist mask 27 in the region for forming
Anisotropic etching is again performed with H to form a recess 29 reaching the insulating film 2. At this time, the silicon substrate 21 not covered with the resist mask 27 is also etched to form the thick portion 8. The insulating film 2 serves as a stopper against the etching agent, and has a great effect that the thickness of the thin portion 7 composed of the insulating film 2 and the silicon layer 3 is maintained at the thickness set in FIG. 2C. There is. Conventionally, the thickness of the thin portion 7 was controlled by controlling the composition of the etching solution and the etching time, so it was difficult to keep the thickness of the thin portion 7 within a narrow allowable range. Since the stopper serves as a stopper and is not further etched, the thickness of the thin portion 7 can be accurately controlled. After the etching is completed, the resist masks 26, 27 and 28 are removed. As a result, the diaphragm shown in FIG. 1 is manufactured.

FIG. 3 is a sectional view showing the order of steps for explaining the method for manufacturing the upper glass of FIG.

First, as shown in FIG. 3A, the thickness is about 5
Photoresist masks 31 and 32 are provided on the upper surface and the lower surface of the glass plate 11 of 00 μm, and a window 33 is opened in a region where the recess 13 is formed to expose the surface of the glass plate 11. Although various materials can be used for the glass plate 11, Pyrex glass or the like is suitable.

Next, as shown in FIG. 3B, the opening 33 is formed.
Etching is performed to form the concave portion 13.

Next, as shown in FIG. 3C, the mask 3
1, 32 are removed, and a new photoresist mask 34,
35 is provided. At this time, the recess 13 is covered. A window 36 is opened in the area where the recess 12 is formed.

Next, as shown in FIG. 3D, etching is performed through the window 36 to a depth of about 2 to 3 μm to form the recess 1
Form 2.

Next, as shown in FIG. 3E, after removing the photoresist masks 34 and 35, the upper electrode 14 and the connection wiring 15 are formed by vapor deposition and selective removal of metal.
Thereby, the upper glass plate 11 shown in FIG. 1 is obtained.

Upper glass plate 1 obtained as described above
1 is placed on the silicon layer 3 of the diaphragm, the upper electrode 14 and the lower electrode 4 are aligned, and they are airtightly bonded by an anodic bonding method in which a DC voltage of 600 to 1000 V is applied at a temperature of about 400 ° C. The glass on the recess 13 is removed, a metal wire is connected, and the signal processing circuit unit 5 is pulled out to the outside. As a result, the pressure sensor of the first embodiment is obtained.

FIG. 4 is a sectional view of the second embodiment of the present invention.

In the second embodiment, the insulating film 2 of the thin portion 7 is removed and the thin portion 7 is formed only by the silicon layer 3. The thick portion 8 is in contact with the silicon layer 3 via the insulating film 2. In this way, even with a small pressure, the thin portion 7
Can be easily bent, and the detection sensitivity can be increased. Since the silicon layer 3 is hardly attacked by the etching agent that removes the insulating film 2, the thickness of the thin portion 7 is maintained at the thickness when the silicon plate 21 is polished. The other points are the same as in the first embodiment.

In the first and second embodiments, the silicon substrate 1 is completely insulated from the silicon layer 3 by the insulating film 2 and all electric signals are taken out from above the silicon layer 3. This shows that no matter where the silicon substrate 1 is attached, the silicon layer 3 is always insulated and has a great advantage that it is not affected by the place of attachment.

However, when the pressure sensor is mounted on the printed circuit board, the silicon substrate 1 of the pressure sensor is attached to the wiring or land of the printed circuit board, and the input / output signals of the pressure sensor are sent to the wiring of the printed circuit board. There are many. In such a case, if the input / output section of the signal processing circuit section of the pressure sensor is connected to the silicon substrate, the input / output signal of the pressure sensor can be sent by simply attaching the pressure sensor to the wiring or land of the printed circuit board. It is convenient because it can be fed to the wiring.

FIG. 5 is a bottom view and a sectional view taken along the line AA 'of the third embodiment of the present invention.

The third embodiment is a pressure sensor devised to meet the above demand. Under the signal processing circuit portion 5, the silicon substrate 1 is etched to a depth reaching the insulating film 2 to form a groove 41, and a plurality of truncated pyramidal silicon islands 4 are formed.
2a, 42b, 42c are formed. Silicon Island 42
Metal films 45, 46 are formed on the lower surfaces of a, 42b, 42c and the lower surface of the silicon substrate 1 so that they can be soldered to the wiring of the printed circuit board. These silicon islands 42a, 42b and 42c are completely insulated from the rest of the silicon substrate 1. Silicon island 42a,
Holes 43a, 43b, in the insulating film 2 above 42b, 42c,
Open 43c. One of the element regions 23 of the signal processing circuit unit 5 is connected to the silicon island 4 through the hole 43b by the connection wiring 44b.
Connect to 2b. Other silicon islands 42a and 42c are similarly connected to other element regions of the signal processing circuit unit 5. By soldering these silicon islands 42a, 42b, 42c to the wiring of the printed circuit board, the input / output signals of the pressure sensor can be passed to the wiring of the printed circuit board.

Although three silicon islands are provided in the above embodiment, the silicon islands may be provided in a necessary number, and the number is not limited to three. Other than the above, it is the same as the first embodiment. It is obvious that the structure having the silicon islands can be applied to the second embodiment.

[0072]

As described above, according to the present invention, the silicon substrate and the silicon layer are bonded together via the insulating film,
Since the thickness of the thin portion is determined by polishing the silicon layer with high accuracy and adjusting the thickness, it is possible to keep the thickness of the thin portion within the range of narrow variation, and pressure with uniform sensitivity. The sensor can be manufactured with high yield and stably.

Further, in the present invention, since the silicon layer including the lower electrode and the signal processing circuit portion is insulated and separated from the silicon substrate by the insulating film, the electric portion including the lower electrode and the signal processing circuit portion is insulated and separated from the silicon substrate. , The degree of freedom of the mounting location of the pressure sensor is increased.

Furthermore, according to the present invention, a part of the silicon substrate is selectively removed to form an insulated island, and the input / output section of the signal processing circuit section can be connected to this island. The input / output portion of the pressure sensor can be electrically connected to the wiring of the printed circuit board only by attaching the to the wiring or land of the printed circuit board.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the present invention.

2A to 2D are cross-sectional views showing the method of manufacturing the diaphragm in FIG. 1 in order of steps for explaining the method.

3A to 3C are cross-sectional views showing the method of manufacturing the upper glass in FIG. 1 in order of steps for explaining the method.

FIG. 4 is a sectional view of a second embodiment of the present invention.

FIG. 5 is a bottom view and AA ′ of the third embodiment of the present invention.
It is a line sectional view.

FIG. 6 is a cross-sectional view of an example of a conventional capacitance type pressure sensor.

7A to 7C are cross-sectional views showing the method of manufacturing the diaphragm in FIG. 6 in order of steps for explaining the method.

8A to 8C are cross-sectional views showing the method of manufacturing the upper glass plate in FIG. 6 in order of steps for explaining the method.

[Explanation of symbols]

 1 Silicon Substrate 2 Insulating Film 3 Silicon Layer 4 Lower Electrode 5 Signal Processing Circuit Section 6 Connection Wiring 7 Thin Section 8 Thick Section 11 Upper Glass Plate 12, 13 Recess 14 Upper Electrode

Claims (11)

[Claims] 1. A single-conductivity-type single-crystal silicon layer provided on a silicon substrate via an insulating film, a lower electrode provided on the surface of the silicon layer, and the silicon substrate facing the lower electrode. A diaphragm having a thin portion formed by selectively removing the region, an upper glass plate having an upper electrode attached to the upper surface of the diaphragm and facing the lower electrode at a distance, and a surface of the silicon layer. An electrostatic capacitance type pressure sensor, comprising: a signal processing circuit unit that is provided to calculate a pressure value by receiving signals from the lower electrode and the upper electrode. 2. The capacitance type pressure sensor according to claim 1, wherein the thin portion is composed of the insulating film and the silicon layer. 3. The capacitance type pressure sensor according to claim 1, wherein the thin portion is composed of only the silicon layer. 4. The capacitance type according to claim 1, wherein the thin portion has a thick portion which is formed of a part of the silicon substrate and is thicker than the thin portion, in a central portion of the thin portion. Pressure sensor. 5. The capacitance type pressure sensor according to claim 4, wherein the thick portion is in contact with the silicon layer through the insulating film. 6. A silicon island isolated by isolation by selectively removing a part of the silicon substrate, an opening formed by selectively removing the insulating film in contact with the island, and the signal processing circuit through the opening. 2. The capacitance type pressure sensor according to claim 1, further comprising a connection wiring that connects the input / output section of the section and the island. 7. (A) a step of forming an insulating film having a predetermined thickness on the surface of a silicon substrate; a step of providing a monoconducting single-crystal silicon layer on the insulating film; A step of adjusting a predetermined thickness, a step of forming a lower electrode and a signal processing circuit section connected to the lower electrode at a predetermined position on the surface of the silicon layer, and a region of the silicon substrate facing the lower electrode. A diaphragm forming step including a step of selectively removing to form a thin portion; (B) providing an etching resistant resist mask on both surfaces of the glass plate to form a region facing the lower electrode of the diaphragm and the signal processing circuit section; Forming an opening in the resist mask; etching the glass through the opening to form a recess in a region facing the lower electrode and the signal processing circuit section; Upper glass plate including a step of removing the mask mask, a step of forming an upper electrode in a recess facing the lower electrode, and a step of forming a connection wiring for connecting the upper electrode to the signal processing circuit section. Forming step, (C) step of aligning and bonding the upper glass plate on the upper surface of the diaphragm so that the lower electrode and the upper electrode face each other, and at the same time connecting the connection wiring to the signal processing circuit unit And a method of manufacturing an electrostatic capacitance type pressure sensor. 8. The method of manufacturing an electrostatic capacitance type pressure sensor according to claim 7, wherein the step of forming the thin portion is a step of selectively removing and forming only the silicon substrate. 9. The manufacturing method of an electrostatic capacitance type pressure sensor according to claim 7, wherein the step of forming the thin portion is a step of selectively removing the silicon substrate and the insulating film. Method. 10. The capacitance type according to claim 7, further comprising the step of selectively removing a part of the silicon substrate at a central portion of the thin portion to form a thick portion. Manufacturing method of pressure sensor. 11. A portion of the periphery of the silicon substrate is selectively removed until reaching the insulating film to form an island of insulatingly separated silicon, and the insulating film in contact with the island is selectively removed to remove the signal. The method of manufacturing an electrostatic capacitance type pressure sensor according to claim 7, further comprising the step of connecting an input / output section of a processing circuit section to the island.