JP3441961B2 - 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 pressure sensor for detecting a pressure of a fluid, particularly to a structure of a pressure sensor used for controlling an engine of an automobile, etc., and a manufacturing method of the sensor using a semiconductor fine processing technique. is there.

[0002]

2. Description of the Related Art As a conventional pressure sensor, for example, there are pressure sensors described in JP-B-62-502645 and JP-B-6-252420.

The pressure sensor disclosed in Japanese Patent Publication No. 62-502645 is a semiconductor substrate, a central portion which is deformable through a gap on the substrate, a peripheral portion which is joined to the substrate, and an etch channel portion which extends to the central portion through the peripheral portion. We propose a structure and manufacturing method of a pressure sensor that is composed of a solid material having and a material that seals the etch channel.

The pressure sensor described in Japanese Patent Publication No. 6-252420 is a first electrode formed by doping the surface of a semiconductor substrate, and a doped and conductive polycrystalline silicon diaphragm disposed above the first electrode. The second electrode by
It has a cavity formed between the first and second electrodes, and a cavity sealing plug selectively deposited in an opening formed through the diaphragm layer. The second electrode, which is a diaphragm, is displaced due to the difference, and this capacitance change is detected.

[0005]

However, as a problem when manufacturing a semiconductor type pressure sensor on the surface of a semiconductor substrate,
Since the diaphragm sealing method is complicated, it cannot be manufactured at low cost, and the diaphragm that displaces in response to pressure elastically deforms due to its own residual stress. There are things that cannot be obtained.

An object of the present invention is to provide a pressure sensor which can inexpensively seal a diaphragm with a small number of steps.

[0007]

The above object is to provide a semiconductor substrate.
And a scaffolding portion fixed to the surface of the semiconductor substrate,
With a diaphragm that displaces in response to changes in force
In the conductor type pressure sensor, the semiconductor substrate surface and the
Almost constant between 0.1 and 1.3 μm between the diaphragm
And the thickness deposited by the LPCVD method is 1.
With the silicon oxide film smaller than 9 μm,
This is achieved by hermetically sealing. Also, the above purpose
Is a semiconductor substrate and a scaffold that is fixed to the surface of the semiconductor substrate.
A diaphragm that has a portion and that displaces in response to changes in pressure
Of the semiconductor substrate surface and the diaphragm
The space between them is 0.1 to 1.3 μm, which is almost constant.
With the silicon oxide film deposited by the CVD method,
The air gap is hermetically sealed, and a step structure is formed on the diaphragm.
A semiconductor pressure sensor having a structure, the step structure
Are arranged radially toward the outer periphery of the diaphragm.
Will be achieved. Moreover, the above-mentioned purpose is a semiconductor substrate.
A plate, and a scaffold portion fixed to the semiconductor substrate surface,
With a diaphragm that displaces in response to changes in pressure,
There is no 0.1 between the surface of the semiconductor substrate and the diaphragm.
The LPCVD method has an approximately constant 1.3 μm void.
The deposited silicon oxide film is used to clean the voids.
Tightly sealed, and the diaphragm was provided with a step structure.
A semiconductor pressure sensor, wherein the step structure is substantially
Achieved by arranging parallel to the outer circumference of the diaphragm
It

[0008]

1 is a sectional view of a first embodiment in which the present invention is applied to a capacitance type pressure sensor, and FIG.
Shown in.

In this embodiment, the scaffold 10, the diaphragm sealing portion 20, the connecting portion 30, the void 50, the semiconductor substrate 110, the dielectric 120, the fixed electrode 130, the diaphragm wiring 130.
c, barrier layer 140, diaphragm structure 150, LPC
The VD silicon oxide film 160 is used.

A medium to be measured, such as air, applies a pressure to the diaphragm structure 150 through the LPCVD silicon oxide film 160, and the diaphragm structure 1 is adjusted according to the magnitude of the pressure.
50 is displaced. The magnitude of the displacement is proportional to the difference between the pressure in the air gap 50 and the pressure in the air. The air gap 50 is approximately equal to a vacuum when depositing the LPCVD silicon oxide film 30.
Since it is sealed in a vacuum state of Pa to 120 Pa,
This sensor can be used as an absolute pressure sensor. Although not shown, at least the surface of the diaphragm structure 150 on the fixed electrode 130 side or the entire diaphragm structure 150 is made conductive by impurity doping. Therefore, the electrostatic capacitance between the fixed electrode 130 and the diaphragm structure 150 changes according to the pressure of air, and the pressure can be detected.

The semiconductor substrate 110 is a single crystal silicon substrate generally used for semiconductors, that is, SOI (Silicon on I).
nsulator) substrate, an epitaxial substrate, etc. can be used. C- which is known to be highly integrated at low cost
When the MOS device and the pressure sensor of the present invention are formed on the same substrate, an n-type or p-type single crystal CZ substrate having a resistivity of about 8 to 12 Ωcm is used.

The dielectric 120 is a thermal oxide film, a CVD (Chemical Vapor Deposition) oxide film, and C on the semiconductor substrate 110.
It can be formed of a VD nitride film or the like. Considering that the relative permittivity of the silicon oxide film is about 3 to 4 and the CVD nitride film is about 7, the fixed electrode 130 and the semiconductor substrate 110.
The stray capacitance between them is less for the silicon oxide film, which is advantageous. A thermal oxide film (field oxide film) can be used as the dielectric 120 when it is simultaneously formed with a C-MOS device, which leads to a reduction in the number of steps, and thus a more inexpensive pressure sensor can be provided. .

Since the fixed electrode 130 is formed on the semiconductor substrate 110, it has a structure in which it is not displaced by pressure. The fixed electrode 130 is most preferably a polycrystalline silicon film made conductive by impurity doping, and it is inexpensive to process the fixed electrode 130 together with the gate wiring of the CMOS device by the same member. Similarly,
The diaphragm wiring 130c is also formed of the same member as the fixed electrode 130, and plays a role of drawing a wiring from the diaphragm structure 150. If both the fixed electrode 130 and the fixed electrode wiring 130a are conductive films, they can be substituted.
A silicide thin film is also suitable.

The connecting portion 30 has a structure in which the barrier layer 140 on the diaphragm wiring 130c is partially removed to obtain an electrical contact between the diaphragm structure 150 and the diaphragm wiring 130c.

The barrier layer 140 is a diaphragm structure 150.
When it is overloaded, it is prevented from coming into contact with the fixed electrode 130 and electrically short-circuiting, and reducing the surface leak current between the diaphragm structure 150 and the fixed electrode 130. Further, the barrier layer 140 also plays a role of an etching barrier when the void 50 is removed and formed by etching the sacrifice layer of the separation layer 170.

The void 50 determines the capacitance interval between the fixed electrode 130 and the diaphragm structure 150, and is 0.1 to 1.3.
It is obtained by etching away the separation layer 170 deposited with a substantially uniform thickness of μm. Therefore, the void 50
Are kept at a constant interval of approximately 0.1 to 1.3 μm.

Although not shown in the drawing because it is removed by etching, a silicon oxide film such as PSG can be used as an example of the separation layer 170. The scaffold 10 has a diaphragm structure 150 and a semiconductor substrate 1
It is a part that is mechanically fixed to 10. The scaffold 10 is obtained by photolithographically masking the isolation layer 170, followed by partial etching and subsequent formation of the diaphragm structure 150.

Polycrystalline silicon is most suitable for the diaphragm structure 150 in this embodiment, but a pressure sensor having the diaphragm structure 150 hermetically sealed by a conductive or insulating film made of another material can be obtained. I can.
Since the diaphragm structure 150 is deposited on the separation layer 170 deposited with a substantially uniform thickness of 0.1 to 1.3 μm, the diaphragm structure 150 is formed at a substantially uniform distance from the underlying layer after the separation layer 170 is etched.

The diaphragm sealing portion 20 is an end portion of the diaphragm structure 150, and the LPCVD silicon oxide film 16 is formed.
It is a part for hermetically sealing the diaphragm structure 150 by using 0. The shape of the diaphragm sealing portion 20 depends on the manufacturing conditions of the LPCVD silicon oxide film 160 and the amount of the void 50.

Regarding the pressure sensor of the present invention, the condition of the sealing material to be considered when hermetically sealing the void 50 is to have a dense film quality in order to maintain the hermeticity of the void 50 for a long time, and the pressure of the diaphragm structure 150. The void 50 that does not substantially prevent the deformation is formed in the fixed electrode 130 and the diaphragm structure 150.
That is, it has a space between them, is a vacuum in the void 50 to serve as a reference pressure of the pressure sensor, and has an insulating property to prevent charge accumulation and current leakage of the diaphragm structure 150. In the present invention, LPCVD (Low Pressure Chemical Vapor Deposition) is used as a material satisfying all of these conditions.
position) Silicon oxide film is adopted. Since the LPCVD silicon oxide film is deposited at a high temperature (about 700 to 800 ° C.) by thermal energy, the silicon oxide film has a dense film quality as compared with another film formed by the plasma CVD method formed at about 400 ° C. Have. Further, since the surface of the semiconductor substrate has a stepped surface due to the sensor structure, it is necessary to consider step coverage, which is the degree of attachment of the film to the surface of the substrate and the surface perpendicular to the substrate. With the LPCVD silicon oxide film, a deposited film having a thickness of 80% or more can be formed on the side surface portion with respect to the thickness of the surface portion. Another possible material is LPCVD nitride film, but the residual stress of the film during deposition (measured value of about 1.5 Gpa) is much larger than that of silicon oxide film (measured value of 0.15 Gpa), so about 2500 Å or more is deposited. Then, there is a defect that cracks occur due to the residual stress of the film itself.

In the present embodiment, the LPCVD silicon oxide film 160 is manufactured under the following conditions: deposition temperature 720-780 ° C., deposition pressure 30-120 Pa, deposition gas ethyl silicate (TEO).
S: Tetraethylorthosilicate) + oxygen (O ₂ ) was adopted.

FIG. 8 shows an experimental result of a region where the LPCVD silicon oxide film 160 under the above manufacturing conditions can hermetically seal the void 50. A LPCVD silicon oxide film 160 is deposited on a sample having a void amount d of 0.3 to 2.0 μm until the void 50 is hermetically sealed. Next, a cross section of the above sample is taken by SEM (Scan
The minimum film thickness a and the amount of effective voids g required for hermetically sealing the voids were measured by observing with an electron scanning electron microscope. The minimum film thickness a required for hermetically sealing the void is the diaphragm structure 1
It is the thickness from the semiconductor substrate 110 at the place where the void 50 is completely sealed near the end face portion of 50. The effective void amount g is the interval of voids at a point 10 μm inside from the measurement point of a. The minimum film thickness a required for hermetically sealing the voids increased as the void amount d increased as shown by the line a. The effective void amount g also increases as the void amount d increases, as shown by the g line.

When the LPCVD silicon oxide film 160 is deposited to a film thickness of 1.9 to 2.0 μm or more, cracks occur.
This is because the residual stress (thermal stress + true stress) generated when the LPCVD silicon oxide film 160 is deposited is LPCVD.
It is said that this is because the breaking strength of the silicon oxide film 160 itself is exceeded. Such cracks cause dust and reduce the yield of semiconductors. For this reason,
The substantially effective maximum void amount d is limited to 1.3 μm or less. When the void amount d is 0.1 μm or less, LP
The CVD silicon oxide 160 penetrates into the void 50, and the effective void amount is substantially eliminated, which hinders the displacement of the diaphragm structure 150 and thus does not function as a pressure sensor. Therefore, the effective void amount d is 0.1 μm or more. With the above configuration, 0.1
A pressure sensor that can be airtightly sealed in a vacuum state of about 30 Pa to about 120 Pa in a smaller number of steps with a void 50 of ~ 1.3 μm in a smaller number of steps, is inexpensive, has good characteristics because of a small stray capacitance, and is stable and highly reliable for automobiles Can be provided.

Further, since it can be manufactured by using a general IC manufacturing process, it becomes possible to form one chip with the circuit section.
It enables downsizing and price reduction.

FIG. 2A shows a circular diaphragm structure 1
50 and scaffold 10 arrangement, FIG. 2B is a plan view showing the arrangement of the rectangular diaphragm structure 150, the divided fixed electrode 130, and the divided scaffold 10.

In FIG. 2A, the diaphragm structure 150 and the fixed electrode 130 have a perfect circular shape so that the elastic deformation due to the pressure and the residual stress of the diaphragm structure 150 does not occur, and the scaffold 10 has an outer peripheral portion of the diaphragm structure 150. It is an example of dividing and arranging on a concentric circle. The spacing and the number of the scaffolds 10 need to be arranged so as not to affect the etching of the separation layer 170.

The fixed electrode wiring 130a leads the wiring of the fixed electrode 130 to the outside of the diaphragm structure 150. The dummy wiring 130b cancels out the asymmetry of the diaphragm structure 150 caused by the fixed electrode wiring 130a.
The fixed electrode wiring 130a is arranged in point symmetry.

FIG. 2B shows an example in which the diaphragm structure 150 and the fixed electrode 130 are divided into squares so as to prevent unevenness in elastic deformation due to pressure applied to the diaphragm structure 150 or residual stress of the diaphragm structure 150 itself. Is. The scaffold 10 is arranged so as to equally divide the diaphragm structure 150. Also in this case, as in the case of FIG. 2A, the dummy wiring 130b is arranged and the diaphragm structure 15 is formed.
The symmetry of 0 can be maintained.

With the above-described structure, the nonuniformity of the deformation of the diaphragm structure 150 can be reduced, so that the measurement error of the pressure sensor can be reduced.

A sectional view of a second embodiment in which the present invention is applied to a capacitance type pressure sensor is shown in FIG. 3, and a plan view thereof is shown in FIG.

In this embodiment, the scaffold 10, the diaphragm sealing portion 20, the connecting portion 30, the step structure 40, the void 50, the semiconductor substrate 110, the dielectric 120, the fixed electrode 130, the barrier layer 1 are used.
40, a diaphragm structure 150, and an LPCVD silicon oxide film 160.

The difference between FIG. 3 and FIG. 1 is that the step structure 40 is formed in the diaphragm structure 150 by providing a step in the dielectric material 120. After forming the step of the dielectric 120
Since the barrier layer 140 and the separation layer 170 deposited by CVD have almost uniform thickness, the void 50 is kept substantially constant through the diaphragm structure 150 even if the step structure 40 is formed. Although the residual stress generated in the diaphragm structure 150 causes the diaphragm structure 150 itself to be curved and deformed, the displacement amount of the diaphragm structure 150 itself can be reduced due to the effect of reducing the curved deformation of the step structure 40.

When the diaphragm structure 150 is polycrystalline silicon, it is deposited by LPCVD at about 560 ° C. to 680 ° C. In this case, it is known that the residual stress is generated by the thermal stress generated when the deposition temperature is returned to room temperature and the true stress inherent in the film itself. The thermal stress is due to the difference in thermal expansion coefficient between the semiconductor substrate 110 and polycrystalline silicon.
It is known that the true stress varies greatly depending on the manufacturing conditions of polycrystalline silicon, but it occurs due to the difference in the degree of crystallization, and has a stress distribution in the film thickness direction. Since the step structure 40 functions as a rib, the diaphragm structure 150 is prevented from being deformed by this residual stress. The same effect is obtained not only by the concave step structure 40 but also by the fixed electrode 13
It can be achieved by a convex structure with zeros. Another advantage of this step structure is the diaphragm structure 150.
Is that it is possible to limit the direction of deformation due to residual stress. When the rib is formed in a concave shape, the deformation can be limited to the lower side, and when the rib is convex, the deformation can be limited to the upper side.

With the above structure, since the diaphragm structure 150 has the step structure 40 as a means for reducing the deformation due to the residual stress, it is possible to prevent the initial displacement from deviating from a predetermined value and to change the deformation direction. Since it becomes possible to control, the error of the pressure sensor can be reduced.

FIG. 4 shows the plane arrangement of the step structure. Figure 4
FIG. 4A shows a state in which the step structure 40 is concentrically arranged in the circular diaphragm structure 150, and FIG. 4B shows a state in which the step structure 40 is arranged in the radial direction in the circular diaphragm structure 150. 4A shows a structure effective in the presence of a bending moment because the residual stress in the diaphragm structure 150 has a distribution in the thickness direction, and FIG. 4B shows the diaphragm structure 150 having a residual stress in the planar direction. This is an effective structure in some cases.

With the above-mentioned structure, since the diaphragm structure has the step structure which is the means for reducing the deformation due to the residual stress, the measurement error can be reduced and the pressure sensor having the excellent characteristics for the automobile can be provided.

The manufacturing process of the pressure sensor of the present invention is shown in FIG.

The dielectric 1 is formed on the semiconductor substrate 110 for IC manufacture.
20 is formed by thermal oxidation of the semiconductor substrate 110 (FIG. 5).
(A)). Next, the step structure 40 is obtained on the dielectric 120 by masking it by photolithography and then performing dry etching on a predetermined portion (FIG. 5B). The first embodiment can be manufactured by a common process except that FIG. 5B is deleted. FIG. 5C shows a state in which the fixed electrode 130 and the diaphragm wiring 130c are collectively processed from conductive polycrystalline silicon or the like by a photo-etching process.

As a perfect alternative to the steps of FIGS. 5A to 5C, there is a method of simplifying the steps by making the field oxide film of the MOS device and the dielectric 120, the gate wiring and the fixed electrode 130 common. is there. In this case, FIG.
(C) can be replaced with the well-known steps described below. First, a nitride film is formed on the semiconductor substrate 110, and only a portion of the nitride film where a field oxide film is desired to be formed is removed. Next, thermal oxidation is performed to selectively form a field oxide film, and then the nitride film is removed. The gate wiring is formed of a doped polycrystalline silicon film, a silicide film, or the like, and at the same time, the fixed electrode 130 and the diaphragm wiring 130c are collectively processed on the field oxide film.

In FIG. 5D, after the barrier layer 140 of the LPCVD nitride film is deposited, the connection 3 between the diaphragm wiring 130c and the diaphragm structure 150 is formed by a photo-etching process.
It shows how 0 is processed. FIG. 6E shows a state in which the scaffold 10 with the semiconductor substrate 110 of the diaphragm structure 150 is processed by a photo-etching process after depositing the separation layer 170. The thickness of the separation layer 170 is specified to be 0.1 to 1.3 μm. A silicon oxide film is often used for the separation layer 170, and PSG having a high etching rate is used with an HF-based etching solution in this embodiment.

FIG. 6F shows a separation layer 1 obtained by processing the scaffold 10.
After being deposited on 70, the separation layer 170 is used as a base for photo
The diaphragm structure 150 is formed by etching. In order to make the diaphragm structure 150 conductive, there is a method of doping the diaphragm structure 150 with impurities.
As a method of impurity doping, there is a method of performing phosphorus treatment which is solid phase diffusion or ion implantation after depositing polycrystalline silicon as the diaphragm structure 150. Alternatively, there is a method of depositing doped polycrystalline silicon by mixing impurities during the deposition of polycrystalline silicon. When PSG containing a high concentration of p-type or n-type impurities is used for the separation layer 170, the impurities in the PSG are diffused in the solid layer into the polycrystalline silicon by annealing after the deposition of the polycrystalline silicon to conduct the polycrystalline silicon. There is also a way to make it.

FIG. 6G shows a state where the formed separation layer 170 is removed by etching. In the case of the combination of the barrier layer 140 of LPCVD nitride film and the separation layer 170 of PSG, wet etching can be performed with an HF-based etching solution, but in the present embodiment, depending on the side etching amount of the separation layer 170 and the selection ratio of the barrier layer 140. The diameter of the diaphragm structure 150 can be up to about 400 μm.

FIG. 6H shows the LPCVD silicon oxide film 1.
A state in which the diaphragm structure 150 is hermetically sealed by 60 is shown.

The manufacturing conditions of the LPCVD silicon oxide film 160 in this embodiment are as follows: the deposition temperature is 720 to 780 ° C., the deposition pressure is 30 to 120 Pa, and the deposition gas is ethyl silicate (TEO).
S: Tetraethylorthosilicate) + oxygen (O ₂ ) was adopted. Therefore, the void 50 is formed in the LPCVD silicon oxide film 1.
It is possible to hermetically seal in a substantially vacuum state of about 30 Pa to about 120 Pa, which is the pressure at the time of deposition of 60.

By this manufacturing process, a semiconductor type pressure sensor integrated with the CMOS circuit on the same substrate can be manufactured,
Further, it is possible to provide a small-sized and inexpensive pressure sensor that is not easily affected by the residual stress of the diaphragm structure 150.

Although the embodiment in which the present invention is applied to the capacitance type pressure sensor has been described above, the present invention can also be applied to a piezoresistive type pressure sensor having a different detection principle.

FIG. 7 shows a sectional view of a third embodiment in which the present invention is applied to a piezoresistive pressure sensor.

In this embodiment, the scaffold 10, the diaphragm sealing portion 20, the connecting portion 30, the void 50, the semiconductor substrate 110, the dielectric 120, the diaphragm wiring 130c, and the barrier layer 14 are used.
0, diaphragm structure 150, LPCVD silicon oxide film 160, piezoresistive element 200, and conductor 210.

The pressure of air, which is the medium to be measured, is LPCV.
Diaphragm structure 15 via D silicon oxide film 160
Distort 0. The piezoresistive element 200 installed at the place where the strain of the diaphragm structure 150 is maximum changes its resistance value according to this strain. The change in strain resistance is connected to the detection circuit via the conductor 210, the connecting portion 30, and the diaphragm wiring 130c. Therefore, the piezo resistance value changes according to the pressure of the air, and the pressure can be detected. In this embodiment as well, as in the first embodiment, the void 50 of 0.1 to 1.3 μm can be vacuum-sealed, so that it can be used as an absolute pressure sensor.

As is well known, the piezoresistive element 200 is an element having the effect of changing the specific resistance due to strain. When the diaphragm structure 150 is formed of polycrystalline silicon, it is possible to form a piezoresistive element by forming a part of the diaphragm structure 150 itself into a p-type or n-type impurity layer.

The conductor 210 electrically connects the piezoresistive element 200 and the diaphragm wiring 130c.

With the above structure, 0.1
A void 50 of ~ 1.3 μm can be hermetically sealed in a vacuum state of about 30 Pa to 120 Pa in a smaller number of steps, and the diaphragm is completely covered with a silicon oxide film deposited by the LPCVD method. It is possible to provide a stable and highly reliable pressure sensor with good characteristics even for use. Further, the step structure 40, which is a means for reducing the deformation due to residual stress, is attached to the diaphragm structure 150.
Since the initial displacement can be prevented from deviating from a predetermined value and the direction of deformation can be controlled, the error of the pressure sensor can be reduced.

Further, since the semiconductor type pressure sensor integrated with the CMOS circuit on the same substrate can be manufactured, it is possible to form one chip with the circuit portion, and it is possible to reduce the size and cost.

[0054]

According to the present invention, the diaphragm can be sealed at a low cost with a small number of steps.

[Brief description of drawings]

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

FIG. 2 is a plan view of the first embodiment of the present invention.

FIG. 3 is a sectional view of a second embodiment of the present invention.

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

FIG. 5 is a manufacturing process diagram of the present invention.

FIG. 6 is a manufacturing process diagram of the present invention.

FIG. 7 is a sectional view of the third embodiment of the present invention.

FIG. 8 shows conditions under which the pressure sensor of the present invention can be hermetically sealed.

[Explanation of symbols]

10 ... Scaffold, 20 ... Diaphragm sealing part, 30 ... Connection part, 40 ... Step structure, 50 ... Void, 110 ... Semiconductor substrate, 120 ... Dielectric material, 130 ... Fixed electrode, 130a ... Fixed electrode wiring, 130b ... Dummy wiring , 130c ... Diaphragm wiring, 140 ... Barrier layer, 150 ... Diaphragm structure, 160 ... LPCVD silicon oxide film, 170 ... Separation layer, 200 ... Piezoresistive element, 210 ... Conductor, a ... Minimum required for airtight sealing of voids. Film thickness, d ... void amount, g ... effective void amount.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Ichikawa 2477 Takaba, Hitachinaka City, Ibaraki Prefecture Hitachi Car Engineering Co., Ltd. (72) Inventor Seiji Kurio 2477 Takaba, Hitachinaka City, Ibaraki Hitachi Car Engineering Co., Ltd. 72) Inventor Satoshi Shimada 7-1, 1-1 Omika-cho, Hitachi City, Ibaraki Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Akihiko Saito 7-1 Omika-cho, Hitachi City, Ibaraki Hitachi Research Co., Ltd. Hitachi, Ltd. In-house (72) Inventor Keiji Hanzawa 2477 Takaba, Hitachinaka City, Ibaraki Hitachi Car Engineering Co., Ltd. (56) References JP-A-6-252420 (JP, A) JP-A-4-278464 (JP, A) Special Kaihei 6-50986 (JP, A) JP 64-13773 (JP, A) JP 63 -25982 (JP, A) JP 62-232171 (JP, A) JP 10-70287 (JP, A) Special table 62-502645 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) H01L 29/84 G01L 9/04

Claims (6)

(57) [Claims] 1. A semiconductor pressure sensor, comprising: a semiconductor substrate; and a diaphragm having a scaffolding portion fixed to the surface of the semiconductor substrate, the diaphragm being displaced according to a change in pressure, the semiconductor substrate surface and the diaphragm. Between 0.1
To 1.3 μm, and the thickness deposited by LPCVD is less than 1.9 μm.
The semiconductor type pressure sensor, wherein the void is hermetically sealed by the silicon oxide film. 2. The semiconductor pressure sensor according to claim 1, wherein the diaphragm has a step structure. 3. A semiconductor substrate and a scaffolding portion fixed to the surface of the semiconductor substrate,
A diaphragm that is displaced according to a change, and a distance between the surface of the semiconductor substrate and the diaphragm is 0.1.
To 1.3 μm, and a silicon oxide film deposited by the LPCVD method is used.
To hermetically seal the gap, and further to provide a semiconductor type pressure sensor having a step structure on the diaphragm.
A force sensor, wherein the step structure is arranged radially toward substantially the outer circumference of the diaphragm. 4. A semiconductor substrate having a scaffold portion fixed to the semiconductor substrate surface, the pressure
A diaphragm that is displaced according to a change, and a distance between the surface of the semiconductor substrate and the diaphragm is 0.1.
To 1.3 μm, and a silicon oxide film deposited by the LPCVD method is used.
To hermetically seal the gap, and further to provide a semiconductor type pressure sensor having a step structure on the diaphragm.
A semiconductor pressure sensor , wherein the step structure is arranged substantially parallel to the outer circumference of the diaphragm. 5. The claim 1-4, semiconductor pressure sensor, which is a capacitance type
Sa. 6. The claim 1-4, semiconductor pressure sensor, which is a piezoresistive
Sa.