JPH10281862A - Vibration type infrared sensor and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an infrared sensor having high sensitivity, high accuracy and low cost by providing a plate-like conductive vibration gate, a shell covering the gate and held in vacuum therein, and infrared condenser lens of infrared ray provided on an outer surface of the shell. SOLUTION: A first vibration gate 66 is thermally expanded by absorbing infrared ray to the gate 66, and a resonance frequency of a beam is changed by generating a strain between the plate 66 and a base plate 11. This change of the natural frequency is taken out, and hence a value of the ray M can be sensed. An accurate infrared ray incident amount can be measured without influence of temperature fluctuation of a measuring environment by a differential calculation of resonance frequency of the gate 66 and a vibration gate 76. And, the gates 66 and 76 are held in vacuum. Then, the ray passed through a first shell 67 is passed through a space held in high vacuum and efficiently absorbed to the gate 66.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-sensitivity, high-precision, inexpensive vibration-type infrared sensor and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventional infrared thermal sensors are classified into two types: a bolometer type and a pyroelectric type. The pyroelectric type requires a chopper in order to obtain a continuous signal because the signal is obtained by differentiation of heat, and the system becomes complicated.

[0003] Further, in the bolometer, cooling is required in order to increase the sensitivity, which also complicates the system. In addition, both sensors require a technology such as sealcap to perform thermal insulation in an assembly process after the production of a sensor chip.

FIG. 7 is an explanatory view showing the basic structure of a conventional example of a vibrating transducer generally used in the prior art, in which the vibrating transducer is used as a pressure sensor.
For example, it is disclosed in JP-A-7-30128.

The silicon substrate 1 has, for example, a conduction type of n
The electrode 2 is fixed here, and the electrode 2 is connected to the common potential point COM. This silicon substrate 1
A source S is formed by diffusing a p-type impurity on the upper surface of the substrate, and an electrode 3 for extracting the potential of the source S is formed here. A pressure P _M to be measured is applied to the lower surface of the silicon substrate 1.

Also, at a predetermined distance W from the source S, a p-type impurity is similarly diffused into the upper surface of the silicon substrate 1 to form a drain D, where the drain D is formed.
The electrode 4 for extracting the potential of the electrode 4 is formed.

[0007] Above the portion of the predetermined distance W of the silicon substrate 1, the convex portions 5 and 6 are formed apart x _1, impurity functions as has been plate-shaped vibrator conductivity is imparted conductive diffusion Both ends of the vibration gate 7 (for the sake of convenience, a symbol G is sometimes used) are fixed to these convex portions 5 and 6.

That is, the vibration gate 7 and the silicon substrate 1 are arranged apart from each other by x ₁ except for both ends, and the silicon substrate 1 corresponding to the vibration gate 7 has a drain D and a source S (not shown). A channel CNN1 is formed therebetween.

A resistor R1 and a DC power supply E1 are connected in series between the electrode 4 and the common potential point COM, and the potential of the drain D is maintained at a negative potential with respect to the common potential point COM. In addition, a DC power supply E2 is connected to the oscillation gate 7 so as to have a negative potential with respect to the common potential point COM.

FIG. 8 is an explanatory diagram for explaining the operation of FIG. The configuration includes a cross section of the silicon substrate 1 viewed from the longitudinal direction of the vibration gate 7. Since a negative potential is applied from the DC power supply E2 to the vibrating gate 7 functioning as a gate, electrons are transferred from the lower surface of the vibrator 7 to the inside of the silicon substrate 1 (in FIG. ), And conversely, the holes become attracted to the surface.

The channel CNN1 which is a thin P-type conductive layer is formed on the surface by the attracted holes (P-type) and connects the source S (P-type) and the drain D (P-type) with the P-type. Therefore, a current _id1 flows between the source S and the drain D.

The drain D generated by the current _id1
Is subjected to a phase shift by the drain resistance R _D and the capacitance C _D formed between the drain and the silicon substrate 1, and the potential change resulting from the phase shift causes the oscillation gate 7 and the drain D to pass through. changing the electrostatic attraction between changing the distance x _1.

The change in the interval x ₁ causes the channel CNN to change.
1, thereby changing the current _id1 ;
This causes a change in the potential of the drain. Although oscillates by repeating this, the oscillation drain resistance R _D and the drain D and the capacitance C _D and the product of the oscillation angular velocity ω of the oscillation between the silicon substrate 1 (.omega.R _D C _D) is compared to the 1 Continue by choosing to be extremely large.

[0014] In a state where the self oscillation as described above is maintained, the pressure P _M in the silicon substrate 1 is applied as shown, the through projections 5 and 6 for fixing the vibrating gate 7 joined the distortion vibrating gate 7 by the pressure P _M, this corresponds natural frequency changes. Therefore, by taking out a change in the natural frequency, it is possible to detect the value of pressure P _M.

FIG. 9 is a perspective view showing the structure of the specific embodiment of FIG. 7, and FIG. 10 is a sectional view of the vicinity of the center. However, a shell portion and a diaphragm portion covering the vibration gate are omitted. FIG. 11 is an overall side sectional view of a central portion of the vibration gate.

9, FIG. 10, and FIG. 11, a silicon substrate 11 is formed, for example, with an n-type conduction type, and a p-type impurity is diffused on the upper surface of the silicon substrate 11 to form a source S. , wherein an aluminum electrode 12 for taking out the potential of the source S is formed through the wiring portion W _S shown by a dotted line. Further, the pressure P _M is not shown on the lower surface is to be measured here is formed on the diaphragm recessed a silicon substrate 11 is applied.

Also, at a predetermined distance from the source S, a p-type impurity is diffused into the upper surface of the silicon substrate 11 to form a drain D, where the drain D is formed.
Aluminum electrodes 13 for taking out the potential of the are formed through the wiring portion W _D shown by a dotted line.

[0018] Above the silicon substrate 11, the fixed end 14, 15 are spaced apart by a gap x _2, both ends of the polysilicon plate-shaped vibrating gate 16 which impurities are diffused conductivity is imparted, These fixed ends 14 and 15 are integrally fixed. The beam length of the vibration gate 16 is L.
The vibrating gate 16 is connected to the aluminum electrode 1.
Are connected via a wiring portion W _G indicated by 7 and dotted.

That is, the vibration gate 16 and the silicon substrate 1
1 is spaced apart by a gap x ₂ except across the channel CNN2 is formed between the drain D and the source S of the silicon substrate 11 corresponding to the vibration gate 16.

On the drain D, the channel CNN2 and the source S formed on the upper surface of the silicon substrate 11, a protective film 1 having high corrosion resistance to hydrofluoric acid (HF) is formed.
8, for example, _{S i3 N 4, S i C} x N y, S i C, and the like AL ₂ O _3, 2-layer structure film 21 made of an oxide film 19. is formed. The protection film 18 is an insulator similar to the oxide film 19.

A gap is provided between the two-layer structure film 21 and the vibration gate 16 so that the vibration gate 16 can vibrate up and down with the fixed ends 14 and 15 as nodes.
The vibration gauge 22 is configured as described above. 23
Is a shell, and 24 is a diaphragm.

In the description so far, the point that the vibration type infrared sensor is constructed by combining the vibration gauge and the electronic circuit as shown in FIG. 9 has been described. Next, a method of manufacturing the vibration gauge 22 as a component of such a vibration transducer will be described with reference to manufacturing process diagrams shown in FIGS.

Although the manufacturing process shown in FIG. 13 is continuous with the manufacturing process shown in FIG. 12, it is divided into two for convenience of explanation. In the configuration shown in FIG. 9, a portion of the vibration gate 16 and fixed ends 14, 15 for fixing the same at both ends are provided.
Since the cross-sectional structure produced in the course of the manufacturing process is different from the above-mentioned portion, these are separately illustrated in the same process but separated into right and left.

The figure on the left shows the sectional structure of the central part of the vibration gate 16 and the figure on the right shows the sectional structure of the fixed end 14. The fixed end 15 has the same structure as the fixed end 14 and will not be described.

Step 1 shows a gate oxide film forming step. A gate oxide film 31 is formed on an n-type silicon single crystal substrate 30 to a thickness of, for example, about 500 angstroms. In this step, the cross-sectional structures at the center and the fixed end of the vibration gate are formed to be the same. Thereafter, the process proceeds to step 2. Thereafter, each step proceeds according to the step number.

Step 2 shows an ion implantation step. Here, boron is ion-implanted into a predetermined region as a p-type impurity. Thus, corresponding to W _D of (W corresponds to _S in FIG. 9) and the drain part 33 (FIG. 9 source unit 32 of p-type at a predetermined interval W _N plan to form a channel CCN in the central portion of the vibrating gate ), And a p-type gate lead portion 34 (corresponding to _WG in FIG. 9) is formed at the fixed end.

Step 3 shows a channel forming step.
Here, the channel CCN is located at the center of the oscillation gate.
Are formed at predetermined intervals W _N of the channel portions 34 (CC
N2) is ion-implanted with boron at a shallow depth. Thereby, the resistance between the source and the drain can be controlled to a predetermined value. In this case, there is no change at the fixed end.

Step 4 shows a nitride film forming step. In this step, for hydrofluoric acid used in the subsequent step (HF), in order to protect the gate oxide film 31, as a strong resistance insulating film 35 against the hydrofluoric acid, for example S _i C _x N _y
A film is formed on the gate oxide film 31 to a thickness of about 1000 angstroms.

Step 5 shows a first sacrificial layer oxide film forming step. In this step, first, CVD is performed as a lower sacrificial layer for finally forming a void around the oscillation gate 16.
An oxide film 36 is formed on the insulating film 35 to a thickness of about 5000 angstroms by a (Chemical Vapor Deposition) method.
To form

Next, for the fixed end portion, a portion of the gate oxide film 31, the insulating film 35, and the oxide film 36 where the fixed end 14 is to be formed by photolithography is used as an opening 37. Open.

Step 6 shows a polysilicon film forming step. This step is a pre-step for finally forming the vibration gate 16 and the fixed end 14. First, a polysilicon 38 is formed on the oxide film 36 and the opening 37 with a thickness of, for example, about 1 μm. Thereafter, boron is doped to impart conductivity.

Next, a portion corresponding to the vibrating gate 16 and a portion corresponding to the opening 37 are masked by photolithography, and then RIE (Reactive Ion Etching).
A plate-shaped beam 39 which finally becomes a vibration gate by etching the polysilicon 38 into a predetermined shape, and an opening 37
, A Y-shaped support 40 is formed.

Step 7 shows a second sacrificial layer oxide film forming step. In this step, the oxide film 36, the beam 39, and the support post 40 are finally formed to have a thickness of about 5000 angstroms by a CVD method as a sacrificial layer except for the lower side for forming a gap around the vibration gate 16 finally. An oxide film 41 is formed thereon.

Step 8 shows an oxide film etching step. First, the vicinity of the beam 39 is masked at the center of the vibrating gate by photolithography, and the vicinity of the column 40 and the portion of the column 40 except for the Y-shaped central portion 42 are masked at the fixed end. The films 36 and 41 are etched with hydrofluoric acid to form gap corresponding portions 43 and 44.

Step 9 shows a film forming process corresponding to the gap. In this step, an oxide film 45 as a sacrificial layer for introducing an etchant used in a later step is formed by almost 500 times.
The insulating film 35 and the gap corresponding portions 43 and 44 are formed on the entire surface by a CVD method to a thickness of about Å. Thereafter, the oxide film 45 on the Y-shaped central portion 42 is removed by etching using photolithography.

Step 10 shows a shell corresponding portion forming step. 1 is formed on the oxide film 45 formed in Step 9 and the like.
The polysilicon 46 is formed to a thickness of about μm. Thereafter, the stress remaining in the polysilicon of the shell and the vibration gate is removed by heat treatment for a short time by RTA (Rapid Thermal Aneal) to prevent them from being deformed.

Thereafter, masking is performed using photolithography, the polysilicon 46 is etched by RIE, and a shell corresponding portion 47 is formed in a range of a size covering the vibration gate.
To form

Step 11 shows an etching gap forming step. In this step, in order to form a vibration gate and a shell, the oxide film 45 is etched using hydrofluoric acid and removed to form an introduction hole 48, and then a gap is formed through the introduction hole 48. The corresponding parts 43 and 44 are also removed. In this way, the vibration gate 16, the fixed end 14,
And a shell 49 is formed.

Step 12 shows a vacuum sealing step. In this step, the shell 49, the introduction hole 48, the insulating film 3
5 is formed of polysilicon 50 to a thickness of about 5000 angstroms, and the inside of the shell 49 is kept in a vacuum.

Step 13 shows a contact hole forming step. The gate oxide film 31, the insulating film 35, and the polysilicon 50 over the source portion 32 and the drain portion 33.
Are opened using photolithography and RIE to form contact holes 51 and 52. Similarly, a contact hole 54 can be formed in the gate portion.

Step 14 shows a diaphragm forming step. Using a potassium hydroxide (KOH) solution, the bottom of the silicon single crystal substrate 30 is etched so that the central portion is thin and the peripheral portion is thick, so that the diaphragm 5
Form 3

Step 15 shows a bonding process.
Electrode 1 made of aluminum in contact holes 51 and 52
3 and 12 are formed. The above is the manufacturing method of forming the diaphragm by covering the vibration gauge of the vibration type transducer with the shell.

[0043]

However, using such a fine processing technique (micromachining),
The structural type transducer formed on the semiconductor substrate has the following problems.

(1) If the vibration type infrared sensor is used as it is, the sensitivity is not sufficient. (2) In the step of manufacturing a structure such as the vibration gate 16,
Since the silicon oxide films 36 and 41 are used for the sacrificial layer, it is necessary to perform etching with hydrofluoric acid for a long time in the step of removing the silicon oxide films 36 and 41. At this time, a film which is provided on the silicon substrate 11 side and which is not desired to be etched, such as a gate oxide film 19 necessary as an insulating film, is a fluorine-resistant film such as a silicon nitride film 18 which is an insulator similar to the gate oxide film 19. Although it is necessary to protect the protective film 18 having a high acidity of hydrogen hydride, sufficient corrosion resistance has not been obtained.

The present invention solves this problem. An object of the present invention is to provide an inexpensive vibration-type infrared sensor with high sensitivity, high accuracy, and a method of manufacturing the same.

[0046]

In order to achieve this object, the present invention provides: (1) measuring the resonance frequency of a vibrating gate having both ends fixed to a substrate to reduce the infrared radiation applied to the vibrating gate; Vibration type infrared sensor for measuring strain based on
A semiconductor substrate having a conduction type of the above, a channel formed on a surface of the substrate and having a second conduction type opposite to the conduction type and sandwiched by a drain and a source, and a gate oxide formed on the surface of the substrate An insulating film which covers the film and the gate oxide film and has a high resistance to hydrofluoric acid; and polysilicon, both ends of which are fixed to the substrate while maintaining a gap from the surface of the insulating film so as to be displaceable. A plate-shaped conductive vibrating gate which is disposed over the drain, source and channel and is displaced by electrostatic force generated between the drain by self-excited oscillation; and A vibrating infrared sensor comprising a detection unit including a shell and an infrared condenser lens provided on an outer surface of the shell. (2) A vibration-type infrared sensor for measuring distortion based on infrared rays applied to the vibration gate by measuring the resonance frequency of the vibration gate having both ends fixed to the substrate.
A first substrate made of a semiconductor having a first conduction type and a channel formed on a surface of the first substrate and sandwiched between a drain and a source having a second conduction type opposite to the first conduction type, and the first substrate A gate oxide film formed on the surface of the gate oxide film and an insulating film covering the gate oxide film and having high resistance to hydrofluoric acid and a polysilicon, and holding a gap from the surface of the insulating film so as to be displaceable. A plate-shaped conductive vibrating gate and a vibrating gate, both ends of which are fixed to the substrate and are disposed so as to cover the drain, the source, and the channel and are displaced by electrostatic force generated between the drain and the self-oscillation, A detection unit including a shell whose inside is held in a vacuum and an infrared condensing lens provided on an outer surface of the shell; a second semiconductor substrate having a first conductivity type; Form on the surface of the board A channel sandwiched between a drain and a source having a second conductivity type opposite to the conductivity type, a gate oxide film formed on a surface of the second substrate, and a fluoride covering the gate oxide film. Both ends are fixed to the substrate while maintaining a gap from the surface of the insulating film so as to be displaceable, and are disposed so as to cover the drain, the source, and the channel. A plate-shaped conductive vibrating gate displaced by electrostatic force generated between the drain by self-excited oscillation, a shell covering the vibrating gate, and having a vacuum inside, and an infrared reflection provided on the outer surface of the shell And a reference unit having a film. (3) A vibration-type infrared sensor for measuring distortion based on infrared rays applied to the vibration gate by measuring the resonance frequency of the vibration gate having both ends fixed to the substrate.
A semiconductor substrate having a second conduction type formed on a surface of the substrate and having a second conduction type opposite to the conduction type.
A first channel sandwiched between the drain and the first source, a gate oxide film formed on the surface of the substrate, an insulating film covering the gate oxide film and having a high resistance to hydrofluoric acid; Both ends are fixed to the substrate while holding a gap from the surface of the insulating film so as to be displaceable so as to be displaceable, and are disposed to cover the first drain, the first source, and the first channel, and are self-excited. A plate-shaped conductive first vibrating gate displaced by electrostatic force generated between the first drain due to oscillation, a first shell covering the first vibrating gate, and having a vacuum maintained inside; A detection unit comprising: an infrared condenser lens provided on an outer surface of the first shell;
A second conductive type formed on the surface of the semiconductor substrate having the first conductive type and having a second conductive type opposite to the conductive type;
A second channel sandwiched between the drain and the second source, a gate oxide film formed on the surface of the substrate, and an insulating film covering the gate oxide film and having high resistance to hydrofluoric acid. Both ends are fixed to the substrate while maintaining a gap from the surface of the insulating film so as to be displaceable and made of polysilicon, and are disposed over the second drain, the second source, and the second channel, and are self-excited. A plate-shaped conductive second vibrating gate displaced by an electrostatic force generated between the second drain due to the oscillation, a second shell covering the second vibrating gate and holding the inside thereof in a vacuum; A reference unit having an infrared reflective film provided on an outer surface of the second shell. (4) A method for manufacturing a vibration type infrared sensor for measuring the strain applied to both ends of the vibration gate by measuring the resonance frequency of the vibration gate having both ends fixed to the substrate, comprising the following steps. A method for manufacturing a vibration type infrared sensor. (A) A gate oxide film forming step of forming a gate oxide film on a semiconductor substrate having a first conductivity type. (B) an ion implantation step of ion-implanting impurities of the second conductivity type into predetermined regions corresponding to the source, drain and gate leads. (C) forming a polysilicon protective film on the gate oxide film; (D) forming a first sacrificial layer oxide film on the polysilicon protective film. (E) forming a polysilicon film on the first sacrificial layer oxide film; Thereafter, an impurity that becomes the second conductivity type is doped to impart conductivity. A beam forming step of etching the polysilicon film to form a beam corresponding to the vibration gate. (F) forming a second sacrificial layer oxide film on the first sacrificial layer oxide film and the beam; (G) a gap corresponding portion forming step of forming the gap corresponding portion by etching the first and second sacrificial layer oxide films. (H) A gap-forming film forming step of forming a gap-forming oxide film as a sacrificial layer on the entire surface including the polysilicon protective film and the gap-forming portion. (I) forming a polysilicon film on the oxide film corresponding to the gap; Forming a shell corresponding portion by etching the polysilicon film. (J) An etching gap forming step of etching the gap-corresponding oxide film to form an introduction hole, and removing the gap corresponding portion through the introduction hole. (K) A vacuum sealing step of forming a film of a polysilicon film on the shell corresponding portion, the introduction hole, and the polysilicon protective film in a vacuum, and keeping the inside of the shell at a vacuum. (L) forming a heat transfer preventing portion by etching a bottom of the semiconductor substrate having the first conduction type to form a heat transfer preventing portion; (M) forming an infrared condenser lens on the outer surface of the shell corresponding portion; (5) A method for manufacturing a vibration type infrared sensor for measuring the strain applied to both ends of the vibration gate by measuring the resonance frequency of the vibration gate having both ends fixed to the substrate, comprising the following steps. A method for manufacturing a vibration type infrared sensor. (A) A gate oxide film forming step of forming a gate oxide film on a semiconductor substrate having a first conductivity type. (B) an ion implantation step of ion-implanting impurities having the second conductivity type into predetermined regions corresponding to the first and second sources, the first and second drains, and the lead portions of the gate. (C) forming a polysilicon protective film on the gate oxide film; (D) forming a first sacrificial layer oxide film on the polysilicon protective film. (E) forming a polysilicon film on the first sacrificial layer oxide film; Thereafter, an impurity that becomes the second conductivity type is doped to impart conductivity. A beam forming step of etching the polysilicon film to form two beams corresponding to the first and second vibration gates. (F) forming a second sacrificial layer oxide film on the first sacrificial layer oxide film and the beam; (G) etching the first and second sacrificial layer oxide films to obtain 2
A gap corresponding portion forming step of forming a plurality of gap corresponding portions. (H) A gap-forming film forming step of forming a gap-forming oxide film as a sacrificial layer on the entire surface including the polysilicon protective film and the gap-forming portion. (I) forming a polysilicon film on the oxide film corresponding to the gap; Forming a shell corresponding portion by etching the polysilicon film to form two shell corresponding portions. (J) An etching gap forming step of etching the gap-corresponding oxide film to form an introduction hole, and removing the gap corresponding portion through the introduction hole. (K) A vacuum sealing step of forming a film of a polysilicon film on the shell corresponding portion, the introduction hole, and the polysilicon protective film in a vacuum, and keeping the inside of the shell at a vacuum. (L) forming a heat transfer preventing portion by etching a bottom of the semiconductor substrate having the first conduction type to form a heat transfer preventing portion; (M) an infrared reflecting film forming step of forming an infrared reflecting film on the outer surfaces of the two shell corresponding portions, respectively; (N) an infrared light condensing lens forming step of forming an infrared light condensing lens by etching away one of the reflection films. It is what constituted.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a main part of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. In the figure, the configuration of the same symbol as FIG. 11 represents the same function. Hereinafter, only differences from FIG. 11 will be described.

Reference numeral 11 denotes a semiconductor substrate having the first conduction type. In this case, an n-type semiconductor substrate is used. 61 is formed on the surface of the substrate 11 and
A first channel sandwiched between a first drain 62 and a first source 63 having a conduction type opposite to that of the first conduction type. In this case, a p-type semiconductor is used.

Reference numeral 64 denotes a gate oxide film formed on the surface of the substrate 11. An insulating film 65 covers the gate oxide film 64 and has high resistance to hydrofluoric acid. In this case, polysilicon is used.

Reference numeral 66 denotes polysilicon, and both ends are fixed to the substrate 11 while maintaining a gap from the surface of the insulating film 65 so as to be displaceable, and the first drain 62, the first source 63, and the first And a first conductive gate in the form of a plate which is displaced by electrostatic force generated between itself and the first drain 62 by self-excited oscillation.

Reference numeral 67 denotes a first shell which covers the first vibration gate 66 and has an inside kept at a vacuum. Reference numeral 68 denotes an infrared condenser lens provided on the outer surface of the first shell 67. With the above configuration, the detection unit 60 is configured.

Reference numeral 71 denotes a second substrate formed on the surface of the semiconductor substrate 11 and having a conduction type opposite to the conduction type of the substrate 11.
Between the drain 72 and the second source 73
Channel. 74 is a gate oxide film formed on the surface of the substrate 11.

An insulating film 75 covers the gate oxide film 74 and has high resistance to hydrofluoric acid. In this case, polysilicon is used. Numeral 76 is made of polysilicon, and both ends are fixed to the substrate 11 while maintaining a gap from the surface of the insulating film 75 so as to be displaceable, and the second drain 72, the second source 73, and the second channel 71 are formed. And the second drain 7 by self-oscillation.
2 is a plate-shaped conductive second vibration gate which is displaced by an electrostatic force generated between the second vibration gate and the second vibration gate.

Reference numeral 77 denotes a second shell that covers the second vibration gate 76 and has the inside kept at a vacuum. Reference numeral 78 denotes an infrared reflection film provided on the outer surface of the second shell 77. With the above configuration, the reference unit 70 is configured.

In other words, as a configuration of the entire sensor, there are two vibrators 66 and 76 of exactly the same shape with shells 67 and 77, and one vibrator 76 has an infrared reflecting film 78 for the incidence of infrared light. Is added, and another vibrator 66
Is provided with an infrared condenser lens 68 for incident infrared light.

In the above configuration, since a negative potential is applied from the DC power supply E2 to the oscillation gate 66.76 functioning as a gate, electrons are emitted from the oscillation gate 66.76.
From the lower surface to the inside of the silicon substrate 11,
Conversely, holes become attracted to the surface.

Channels 61 and 71, which are thin P-type conductive layers, are formed on the surface by the attracted holes (P-type), and sources 63 and 73 (P-type) and drains 62 and 72 (P-type).
Form) is connected with a P-type.
Current i _d2 flows between the 3,73 and the drain 62 and 72.

This current i_d2Drain 6 caused by
The voltage of 2,72 is the drain resistance R _DAnd the drain and
Capacitance C formed between recon substrate 11_DBy
Phase shift, and the potential change
Oscillating gate 66.76 and drains 62 and 72
Change the electrostatic attraction force during the interval x_TwoTo change.

The change in the interval x ₂ causes the channels 61,
The thickness of 71 is changed, thereby changing the current _id2 , which causes a change in drain potential. This oscillation is repeated, and this oscillation is caused by the capacitance C between the drain resistance R _D and the drains 62 and 72 and the silicon substrate 11.
_The selection is continued so that the product (ωR _D C _D ) of _D and the oscillation angular velocity ω of oscillation becomes extremely large as compared with 1.

In the state where the self-sustained pulsation is maintained as described above, the infrared light that has entered through the infrared condenser lens 68 passes through the first shell 67 and is self-excited.
The (boron) -doped first oscillation gate 66 absorbs it.

The infrared absorption coefficient of the first vibrating gate 66 doped with B (boron) is as large as 200 to 300, and there is no wavelength dependence in the infrared region in the 1 μm to 10 μm band.

When the infrared light is absorbed by the first vibration gate 66, the first vibration gate 66 thermally expands, and distortion occurs between the first vibration gate 66 and the substrate 11.
The resonance frequency of the beam changes. Therefore, the value of the infrared ray M can be detected by extracting the change in the natural frequency.

By performing the differential operation of the resonance frequency with the first vibration gate 66 and the second vibration gate 76, it is possible to accurately measure the amount of incident infrared rays without being affected by the temperature fluctuation of the measurement environment. Can be.

The first vibration gate 66 and the second vibration gate 76 are kept in a vacuum. The degree of vacuum is an important parameter because it affects the magnitude of oscillation of the resonance frequency and the adiabatic effect. The higher the degree of vacuum, the higher the Q, the less the oscillation, and the greater the adiabatic effect. And the first shell 6
The infrared light transmitted through 7 passes through a space maintained at a high degree of vacuum and is efficiently absorbed by the first vibration gate 66.

As a result, (1) Since the sensitivity of the vibrator type infrared sensor is proportional to the gauge factor, the shape such as the length and thickness of the vibrator is controlled, and the degree of vacuum is increased and Q is increased. By lowering the frequency fluctuation, it is possible to obtain a high-sensitivity, high-precision vibration type infrared sensor capable of obtaining a sensitivity higher than that of a commercially available bolometer belonging to the same thermal sensor.

(2) By utilizing a semiconductor process,
Reference oscillator 7 having the same size as detection oscillator 66
6 can be easily formed in one chip. By setting the resonance frequencies of the two vibrators 66 and 76 to be differential, highly accurate infrared detection can be performed without being affected by temperature fluctuations in the measurement environment.

(3) As in the conventional example, the system as a sensor is simplified, for example, a chopper is not required. Therefore, a vibration-type infrared sensor that can reduce the manufacturing cost can be obtained.

(4) Since the sealcaps 67 and 77 are originally provided in the sensor chip, there is no need to perform a sealcap after the sensor is manufactured as in the conventional example. Therefore, the steps in the assembly are simplified and the cost is reduced. Therefore, a vibration type infrared sensor that can further reduce the manufacturing cost can be obtained.

(5) In addition, the insulating films 65 and 75 formed on the outermost surface of the structure of the substrate 11 have sufficient corrosion resistance to the hydrofluoric acid aqueous solution. When the sacrificial layer is etched, the gate oxide film 64,
74 is not exposed to the hydrofluoric acid aqueous solution, and the element structure is not destroyed.

In the above-described embodiment, the substrate 11
Although it has been described above that the detection unit 60 and the reference unit 70 are manufactured, the present invention is not limited to this. The detection unit 60 and the reference unit 70 may be separately manufactured, and output characteristics may be reduced. Of course, only the detection unit 60 may be manufactured.

Next, a manufacturing method for manufacturing only the detection unit 60 as a component of such a vibration type infrared sensor as a single unit will be described in the order of steps with reference to manufacturing process diagrams shown in FIGS.

(1) Step 1 shows a gate oxide film forming step. On an n-type silicon single crystal substrate 101,
The gate oxide film 102 is formed to a thickness of, for example, about 500 angstroms.

(2) Step 2 shows an ion implantation process. Here, boron is used as a p-type impurity,
3. Ions are implanted into predetermined regions corresponding to the drain 104 and the lead portion of the gate.

(3) In step 3, if necessary, the resistance between the source 103 and the drain 104 can be controlled by ion-implanting boron into the channel portion 105 at a shallow depth. is there.

(4) Step 4 shows a step of forming a polysilicon protective film. In this step, the gate oxide film 10 has high resistance to hydrofluoric acid (HF) used in a later step.
The polysilicon protective film 106, which serves as a protective film of No. 2 and is a stable film, is formed on the gate oxide film 102 to a thickness of about 5000 angstroms.

(5) Step 5 shows a first sacrificial layer oxide film forming step. In this step, first, as a lower sacrificial layer for forming a gap around the vibration gate 66, the polysilicon protective film 106 is formed to a thickness of about 5000 angstroms by, for example, a CVD (Chemical Vapor Deposition) method. A first sacrificial layer oxide film 107 is formed thereon.

(6) Step 6 shows a vibration gate forming step. This step is a pre-step for finally forming the vibration gate 16. First, a polysilicon film 108 (not shown) is formed on the first sacrificial oxide film 107 by, for example,
The film is formed with a thickness of about μm. Thereafter, boron is doped to impart conductivity.

Next, a portion corresponding to the vibration gate 16 is masked by photolithography,
Polysilicon 1 by IE (Reactive Ion Etching)
08 (not shown) is etched into a predetermined shape to form a plate-shaped vibration gate 109 that will eventually become the vibration gate 16.

(7) Step 7 shows a step of forming a second sacrificial layer oxide film. In this step, first, the first sacrificial layer is oxidized to a thickness of about 5000 angstroms by, for example, a CVD method as a sacrificial layer of a portion excluding the lower side for finally forming a gap around the oscillation gate 16. On the film 107 and the beam 109, a second sacrificial layer oxide film 111 is formed.

(8) Step 8 shows a gap corresponding portion forming step. First, the vicinity of the oscillation gate 109 is masked at the center of the oscillation gate 16 by the photolithography technique, and then the first sacrificial layer oxide film 107 and the second sacrificial layer oxide film 111 around these are removed by hydrofluoric acid. To form a gap corresponding portion 112.

(9) Step 9 shows a gap-forming film forming step. In this step, a gap corresponding oxide film 113 serving as a sacrificial layer for introducing an etchant, which is used in a later step, is formed with a thickness of about 500 Å on the polysilicon protective film 106 and the gap corresponding part 112. It is formed on the entire surface by the CVD method.

(10) Step 10 shows a shell corresponding portion forming step. A polysilicon film 114 (not shown) is formed on the gap corresponding oxide film 113 formed in Step 9 so as to have a thickness of about 1 μm.

Thereafter, masking is performed using a photolithography technique, the polysilicon film 114 is etched by RIE, and a shell corresponding portion 115 is formed in a range of a size covering the vibration gate 16.

(11) Step 11 shows an etching gap forming step. In this step, in order to form the vibration gate 16 and the shell corresponding portion 115, while etching the gap corresponding oxide film 113 using hydrofluoric acid,
This is removed to form the introduction hole 116, and then the gap corresponding portion 112 is also removed through the introduction hole 116. Thus, the vibration gate 16 and the shell corresponding portion 115 are formed.

(12) Step 12 shows a vacuum sealing step. In this step, the shell corresponding portion 115, the introduction hole 116, and the polysilicon protective film 106 are formed with a polysilicon film 117 to a thickness of about 1 μm in a vacuum, and the inside of the shell 23 is kept in a vacuum. I do.

(13) Step 13 shows a step of forming a heat transfer preventing section. Using potassium hydroxide (KOH) solution,
So that the center is thin and the periphery is thick
Etching the bottom of the silicon single crystal substrate 101,
The heat transfer preventing portion 118 is formed. Heat transfer prevention part 118
Is to prevent the heat generated by the measured infrared ray from escaping to the base, for example, to which the vibrator-type infrared sensor is mounted, and to end the heat.

(14) Step 14 shows a step of forming an infrared condenser lens. An infrared condenser lens 119 is formed on the outer surface of the shell corresponding portion 115. In this case, it is formed by applying an organic resin. .

According to the manufacturing method of the present invention as described above, a highly sensitive, highly accurate and inexpensive vibration type infrared sensor having only the detection unit 60 can be manufactured inexpensively and reliably using the conventional semiconductor process. A method of manufacturing a vibrating infrared sensor that can be obtained can be obtained.

Next, a method of manufacturing the detection unit 60 and the reference unit 70 as components of such a vibration type infrared sensor on the substrate 201 will be described with reference to a manufacturing process diagram shown in FIG. .

(1) Step 1 shows a gate oxide film forming step. On an n-type silicon single crystal substrate 201,
The gate oxide film 202 is formed to a thickness of, for example, about 500 angstroms.

(2) Step 2 shows an ion implantation step. Here, boron is used as a p-type impurity in the first and second p-type impurities.
Sources 203 and 204, and first and second drains 20
Ions are implanted into predetermined regions corresponding to 5, 206 and the gate lead.

(3) In step 3, if necessary, boron is ion-implanted into the first and second channel portions 207 and 208 at a shallow depth, so that the source-drain region 203-205, It is possible to control the resistance value between 204 and 206.

(4) Step 4 shows a step of forming a polysilicon protective film. In this step, the gate oxide film 20 has high resistance to hydrofluoric acid (HF) used in a later step.
A polysilicon protective film 209 which functions as a protective film of No. 2 and is a stable film is formed on the gate oxide film 202 with a thickness of about 5000 Å.

(5) Step 5 shows a step of forming a first sacrificial layer oxide film. In this step, first, as a lower sacrificial layer for forming a void around the vibrating gates 66 and 76, for example, a CVD (Chemical Vapor Depositio) is used.
The first sacrificial oxide film 211 is formed on the polysilicon protective film 209 to a thickness of about 5000 angstroms by the n) method.
To form

(6) Step 6 shows a vibration gate forming step. This step is a pre-step for finally forming the vibration gates 66 and 76. First, the first sacrificial layer oxide film 2
11, a polysilicon film 210 (not shown) is formed to a thickness of, for example, about 1 μm. Thereafter, boron is doped to impart conductivity.

Next, after masking the portions corresponding to the vibrating gates 66 and 76 by photolithography, the polysilicon 210 (not shown) is formed into a predetermined shape by RIE (Reactive Ion Etching). Etching is performed to form first and second plate-shaped vibration gates 212 and 213 that will eventually become the vibration gates 66 and 76.

(7) Step 7 shows a second sacrificial layer oxide film forming step. In this step, first, as a sacrifice layer except for the lower side for forming a gap around the vibration gates 66 and 76, 5000 is formed by, for example, the CVD method.
The first sacrificial layer oxide film 21 is formed to a thickness of about angstrom.
A second sacrificial layer oxide film 214 is formed on the first, second and first plate-shaped vibration gates 212 and 213.

(8) Step 8 shows a gap corresponding portion forming step. First, by the photolithography technique, the vibration gate 212,
After masking the vicinity of 213, the first sacrifice layer oxide film 211 and the second sacrifice layer oxide film 214 around them are etched with hydrofluoric acid to form gap corresponding portions 215 and 216.

(9) Step 9 shows a gap forming film forming step. In this step, the gap corresponding oxide film 217 as a sacrificial layer for introducing an etching solution, which is used in a later step, is formed to a thickness of about 500 Å, and the polysilicon protective film 209 and the gap corresponding parts 215, 2 are formed.
16 is formed on the entire surface including the upper surface by the CVD method.

(10) Step 10 shows a shell corresponding portion forming step. A polysilicon film 218 (not shown) is formed on the gap corresponding oxide film 217 formed in Step 9 so as to have a thickness of about 1 μm.

Thereafter, masking is performed using a photolithography technique, the polysilicon film 218 is etched by RIE, and shell corresponding portions 219 and 221 are formed in a range of a size covering the vibration gates 66 and 76.

(11) Step 11 shows an etching gap forming step. In this step, the vibration gates 66, 7
6 and the shell corresponding portions 219 and 221 are formed by etching the gap corresponding oxide film 217 using hydrofluoric acid while removing the gap corresponding oxide film 217 to form the introduction hole 222.
Next, the gap corresponding portions 215, 2
16 is also removed. In this way, the vibration gate 66,
76 and shell corresponding parts 219 and 221 are formed.

(12) Step 12 shows a vacuum sealing step. In this step, the shell corresponding parts 219, 22
1, the introduction hole 222, the polysilicon protective film 209,
The polysilicon film 223 is formed to a thickness of about 1 μm, and the inside of the shells 67 and 77 is kept at a vacuum.

(13) Step 13 shows a step of forming a heat transfer preventing portion. Using potassium hydroxide (KOH) solution,
So that the center is thin and the periphery is thick
Etching the bottom of the silicon single crystal substrate 201,
A heat transfer prevention part 224 is formed. Heat transfer prevention part 224
Is to prevent the heat generated by the measured infrared ray from escaping to the base, for example, to which the vibrator-type infrared sensor is mounted, and to end the heat.

(14) Step 14 shows a step of forming an infrared reflective film. An infrared reflecting film 225 is formed on outer surfaces of the shell corresponding portions 219 and 221. In this case, it is formed of vapor-deposited aluminum. .

(15) Step 15 shows a step of forming an infrared condenser lens. One of the reflection films 225 is etched away to form an infrared condenser lens 226. In this case, it is formed by applying an organic resin. .

According to the manufacturing method of the present invention as described above, the high-sensitivity, high-accuracy, inexpensive detection unit 60 and the reference unit 70 are combined with the conventional vibration-type infrared sensor manufactured on the substrate 201 by the conventional method. It is possible to obtain a method of manufacturing a vibration type infrared sensor which can be manufactured inexpensively and reliably using a semiconductor process.

[0108]

As described above in detail with the embodiments, according to the first aspect of the present invention, (1) the sensitivity of the vibrator type infrared sensor is proportional to the gauge factor, Vibration type infrared that can control the shape of length, thickness, etc., and increase the degree of vacuum and increase Q to reduce frequency fluctuations, thereby obtaining a sensitivity higher than that of a commercially available bolometer belonging to the same thermal sensor. A sensor is obtained.

(2) By using a semiconductor process,
A reference oscillator having the same size as the detection oscillator can be easily formed in one chip. (3) As in the conventional example, the system as a sensor is simplified, for example, a chopper is not required. Therefore, a vibration-type infrared sensor that can reduce the manufacturing cost can be obtained.

(4) Since the sealcap is originally included in the sensor chip, there is no need to perform the sealcap after the sensor is manufactured as in the conventional example. Therefore, the steps in the assembly are simplified and the cost is reduced. Therefore,
A vibration type infrared sensor that can reduce the manufacturing cost is obtained.

(5) In addition, the insulating film formed on the outermost surface of the substrate structure has sufficient corrosion resistance of the hydrofluoric acid aqueous solution, and during the manufacturing process of the vibration gate, the gate oxide is formed during the etching of the sacrificial layer. The device structure is not destroyed by exposing the film to the hydrofluoric acid aqueous solution.

According to the second aspect of the present invention, by setting the resonance frequency of the two vibrators to be differential, it is possible to perform highly accurate infrared detection which is not affected by the temperature fluctuation of the measurement environment.

According to the third aspect of the present invention, since the detection unit and the reference unit can be formed simultaneously on the same substrate by using a semiconductor process, the formation conditions can be made the same and the same shape can be obtained. Since the detection unit and the reference unit can be formed, disturbances such as a measurement environment can be canceled more accurately by differential calculation, and a highly accurate vibration type infrared sensor can be obtained.

According to the fourth aspect of the present invention, a vibrating infrared sensor having a high sensitivity, high accuracy, and a low-cost detection unit alone can be manufactured at a low cost and reliably using a conventional semiconductor process. A method for manufacturing an infrared sensor can be obtained.

According to the fifth aspect of the present invention, a high-sensitivity, high-accuracy, inexpensive detection unit and a reference unit are provided by using a vibration type infrared sensor manufactured on the same substrate by using a conventional semiconductor process. Thus, it is possible to obtain a method of manufacturing a vibration type infrared sensor which can be manufactured inexpensively and reliably.

Therefore, according to the present invention, it is possible to realize an inexpensive vibration-type infrared sensor with high sensitivity, high precision, and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an illustration of a method of manufacturing a vibration type infrared sensor having only a detection unit.

FIG. 4 is a diagram illustrating a method of manufacturing a vibration type infrared sensor having only a detection unit.

FIG. 5 is a diagram illustrating a method of manufacturing a vibration type infrared sensor in which a detection unit and a reference unit are manufactured on the same substrate.

FIG. 6 is a diagram illustrating a method of manufacturing a vibration type infrared sensor in which a detection unit and a reference unit are manufactured on the same substrate.

FIG. 7 is an explanatory diagram showing the basic configuration of a conventional example generally used in the related art.

FIG. 8 is an operation explanatory diagram of FIG. 7;

FIG. 9 is a perspective view showing a configuration of a specific example of FIG. 7;

FIG. 10 is a cross-sectional view near the center of FIG. 9;

11 is an overall side sectional view of a central portion of the vibration gate 16 of FIG.

FIG. 12 is an explanatory view of the manufacturing process in FIG. 9;

FIG. 13 is an explanatory view of the manufacturing process in FIG. 9;

[Explanation of symbols]

 Reference Signs List 11 silicon substrate 60 detection unit 61 first channel 62 first drain 62 63 first source 64 gate oxide film 65 insulating film 66 first vibration gate 67 first shell 68 infrared condenser lens 70 reference unit 72 Second drain 73 Second source 74 Gate oxide film 75 Insulating film 76 Second vibrating gate 77 Second shell 78 Infrared reflecting film 101 Substrate 102 Gate oxide film 103 Source 104 Drain 105 Channel section 106 Polysilicon protective film 107 first sacrificial layer oxide film 108 polysilicon film 109 vibration gate 111 second sacrificial layer oxide film 112 gap corresponding portion 113 gap corresponding oxide film 114 polysilicon film 115 shell corresponding portion 116 introduction hole 117 polysilicon film 118 heat transfer preventing portion 119 Condensing lens 201 for external line 201 Substrate 202 Gate oxide film 203 First source 204 Second source 205 First drain 206 Second drain 207 First channel section 208 Second channel section 210 Polysilicon film 209 Polysilicon Protective film 211 First sacrifice layer oxide film 212 First oscillating gate 213 Second oscillating gate 214 Second sacrifice layer oxide film 215 Gap corresponding portion 216 Gap corresponding portion 217 Gap corresponding oxide film 218 Polysilicon film 219 Shell corresponding portion 221 Shell corresponding part 222 Introducing hole 223 Polysilicon film 224 Heat transfer preventing part 225 Infrared reflecting film 226 Infrared condensing lens

Claims (5)

[Claims] 1. A vibration type infrared sensor for measuring a strain based on infrared rays applied to a vibration gate by measuring a resonance frequency of a vibration gate having both ends fixed to a substrate, wherein the semiconductor has a first conduction type. A substrate, a channel formed on the surface of the substrate, sandwiched between a drain and a source having a second conductivity type opposite to the conduction type, a gate oxide film formed on the surface of the substrate, and the gate oxide film An insulating film that covers the surface of the substrate and is made of polysilicon having a high resistance to hydrofluoric acid, and is fixed to both sides of the insulating film so as to be displaceable while maintaining a gap from the surface of the insulating film. And a plate-shaped conductive vibrating gate displaced by electrostatic force generated between the drain by self-excited oscillation and a shell covered with the vibrating gate and kept inside vacuum. A vibration type infrared sensor, comprising: a detection unit including an infrared condenser lens provided on an outer surface of the shell. 2. A vibration type infrared sensor for measuring distortion based on infrared rays applied to a vibration gate by measuring a resonance frequency of a vibration gate having both ends fixed to a substrate, wherein the semiconductor has a first conduction type. A first substrate formed on a surface of the first substrate and a channel formed on a surface of the first substrate and having a second conduction type opposite to the conduction type and sandwiched by a drain and a source; A gate oxide film and an insulating film which covers the gate oxide film and has a high resistance to hydrofluoric acid, and a polysilicon, which is displaceable, holds a gap from the surface of the insulating film and has both ends of the substrate. And a plate-shaped conductive vibrating gate displaced by electrostatic force generated between the drain due to self-excited oscillation and disposed over the drain, source and channel, and a vacuum covering the vibrating gate and covering the inside. A detection unit including a held shell and an infrared condensing lens provided on an outer surface of the shell; a second semiconductor substrate having a first conductivity type; and a detection unit formed on a surface of the second substrate. A channel sandwiched between a drain and a source having a second conductivity type opposite to the conductivity type, a gate oxide film formed on a surface of the second substrate, and a fluoride covering the gate oxide film. Both ends are fixed to the substrate while maintaining a gap from the surface of the insulating film so as to be displaceable, and are disposed so as to cover the drain, the source, and the channel. A plate-shaped conductive vibrating gate displaced by electrostatic force generated between the drain by self-excited oscillation, a shell covering the vibrating gate, and having a vacuum inside, and an infrared reflection provided on the outer surface of the shell With membrane And a reference unit comprising: a vibration type infrared sensor. 3. A vibrating infrared sensor for measuring a distortion based on an infrared ray applied to a vibrating gate by measuring a resonance frequency of a vibrating gate having both ends fixed to a substrate, wherein the semiconductor has a first conduction type. A first channel formed between a first drain and a first source formed on a surface of the substrate and having a second conduction type opposite to the conduction type formed on the surface of the substrate; and a first channel formed on the surface of the substrate. A gate oxide film and an insulating film which covers the gate oxide film and has a high resistance to hydrofluoric acid, and a polysilicon, which is displaceable, holds a gap from the surface of the insulating film and has both ends of the substrate. And a plate-shaped conductive material which is disposed to cover the first drain, the first source, and the first channel and is displaced by electrostatic force generated between the first drain by self-pulsation. 1
A detection unit comprising: a vibrating gate, a first shell that covers the first vibrating gate, the inside of which is kept in a vacuum, and an infrared condenser lens provided on an outer surface of the first shell. A second conductive type formed on the surface of the semiconductor substrate having the first conductive type and having a second conductive type opposite to the conductive type;
A second channel sandwiched between the drain and the second source, a gate oxide film formed on the surface of the substrate, and an insulating film covering the gate oxide film and having high resistance to hydrofluoric acid. Both ends are fixed to the substrate while maintaining a gap from the surface of the insulating film so as to be displaceable and made of polysilicon, and are disposed over the second drain, the second source, and the second channel, and are self-excited. A plate-shaped conductive second vibrating gate displaced by an electrostatic force generated between the second drain due to the oscillation, a second shell covering the second vibrating gate and holding the inside thereof in a vacuum; A reference unit having an infrared reflecting film provided on an outer surface of the second shell; and a vibration type infrared sensor. 4. A method of manufacturing a vibration type infrared sensor for measuring a strain applied to both ends of a vibration gate by measuring a resonance frequency of a vibration gate having both ends fixed to a substrate, comprising the following steps: A method for manufacturing a vibration infrared sensor. (A) A gate oxide film forming step of forming a gate oxide film on a semiconductor substrate having a first conductivity type. (B) an ion implantation step of ion-implanting impurities of the second conductivity type into predetermined regions corresponding to the source, drain and gate leads. (C) forming a polysilicon protective film on the gate oxide film; (D) forming a first sacrificial layer oxide film on the polysilicon protective film. (E) forming a polysilicon film on the first sacrificial layer oxide film; Thereafter, an impurity that becomes the second conductivity type is doped to impart conductivity. A beam forming step of etching the polysilicon film to form a beam corresponding to the vibration gate. (F) forming a second sacrificial layer oxide film on the first sacrificial layer oxide film and the beam; (G) a gap corresponding portion forming step of forming the gap corresponding portion by etching the first and second sacrificial layer oxide films. (H) A gap-forming film forming step of forming a gap-forming oxide film as a sacrificial layer on the entire surface including the polysilicon protective film and the gap-forming portion. (I) forming a polysilicon film on the oxide film corresponding to the gap; Forming a shell corresponding portion by etching the polysilicon film. (J) An etching gap forming step of etching the gap-corresponding oxide film to form an introduction hole, and removing the gap corresponding portion through the introduction hole. (K) A vacuum sealing step of forming a film of a polysilicon film on the shell corresponding portion, the introduction hole, and the polysilicon protective film in a vacuum, and keeping the inside of the shell at a vacuum. (L) forming a heat transfer preventing portion by etching a bottom of the semiconductor substrate having the first conduction type to form a heat transfer preventing portion; (M) forming an infrared condenser lens on the outer surface of the shell corresponding portion; 5. A method of manufacturing a vibration type infrared sensor for measuring a strain applied to both ends of a vibration gate by measuring a resonance frequency of a vibration gate having both ends fixed to a substrate, comprising the following steps: A method for manufacturing a vibration infrared sensor. (A) A gate oxide film forming step of forming a gate oxide film on a semiconductor substrate having a first conductivity type. (B) an ion implantation step of ion-implanting impurities having the second conductivity type into predetermined regions corresponding to the first and second sources, the first and second drains, and the lead portions of the gate. (C) forming a polysilicon protective film on the gate oxide film; (D) forming a first sacrificial layer oxide film on the polysilicon protective film. (E) forming a polysilicon film on the first sacrificial layer oxide film; Thereafter, an impurity that becomes the second conductivity type is doped to impart conductivity. A beam forming step of etching the polysilicon film to form two beams corresponding to the first and second vibration gates. (F) forming a second sacrificial layer oxide film on the first sacrificial layer oxide film and the beam; (G) etching the first and second sacrificial layer oxide films to obtain 2
A gap corresponding portion forming step of forming a plurality of gap corresponding portions. (H) A gap-forming film forming step of forming a gap-forming oxide film as a sacrificial layer on the entire surface including the polysilicon protective film and the gap-forming portion. (I) forming a polysilicon film on the oxide film corresponding to the gap; Forming a shell corresponding portion by etching the polysilicon film to form two shell corresponding portions. (J) An etching gap forming step of etching the gap-corresponding oxide film to form an introduction hole, and removing the gap corresponding portion through the introduction hole. (K) A vacuum sealing step of forming a film of a polysilicon film on the shell corresponding portion, the introduction hole, and the polysilicon protective film in a vacuum, and keeping the inside of the shell at a vacuum. (L) forming a heat transfer preventing portion by etching a bottom of the semiconductor substrate having the first conduction type to form a heat transfer preventing portion; (M) an infrared reflecting film forming step of forming an infrared reflecting film on the outer surfaces of the two shell corresponding portions, respectively; (N) an infrared light condensing lens forming step of forming an infrared light condensing lens by etching away one of the reflection films.