JP2000022170A - Electronic component and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component that is made thinner and has strength improved with respect to external pressure such as atmospheric pressure. SOLUTION: This electronic component is provided with a sealed space 2c between a support substrate 1a and a lid substrate 1c, where the pressure is reduced to below atmospheric pressure. Sealed parts 8a, 9a, 11, 12 are housed in this sealed space 2c. At least one support body 13 is provided between the support substrate 1a and the lid substrate 1c in the sealed space 2c, and the two substrates support each other against the atmospheric pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic components such as an angular velocity sensor and an acceleration sensor formed by using a photo-etching technique, a semiconductor fine processing technique and the like.

[0002]

2. Description of the Related Art Conventionally, ultra-small electronic components such as angular velocity sensors, acceleration sensors, and pressure sensors have been manufactured using photoetching technology and semiconductor fine processing technology. Referring to FIGS. 10 and 11, an angular velocity sensor 20 will be described as a conventional electronic component.

[0003] Reference numeral 1a denotes a supporting substrate made of Pyrex glass, which has a concave portion 2 at the center. Depressions 2a, 2a are respectively formed in the center of one opposed inner wall of the recess 2. Upper surface 1a 'of this support substrate 1a and depression 2a
On the upper side of the concave portion 2 including the above, there are provided functional elements described below, all of which are formed by processing one silicon thin film 1b.

The upper surface 1 of the support substrate 1a on the side of the depressions 2a, 2a
Fixed electrodes 3 and 4 are respectively formed on a ′. Fixed comb electrodes 3a, 4a extending from the fixed electrodes 3, 4 in opposite directions are formed above the depressions 2a, 2a.

Further, fixed electrodes 5 and 6 are formed on the upper surface 1a 'of the support substrate 1a at the center of another opposed inner wall of the recess 2 respectively. Fixed beams 7, 7 are connected to the fixed electrodes 5, 6, respectively. U-shaped outer movable beams 8a, 8a are respectively connected to the fixed beams 7, 7 at their midpoints. The U-shaped tips of the outer movable beams 8a are connected to the outer corners of the rectangular vibration weights 11 and 12, respectively.

Further, outer movable beams 8 on both sides of the fixed beams 7, 7 are provided.
Inner movable beams 9a, 9a extending in opposite directions from a, 8a are connected to inner corners of the vibrating weights 11, 12, respectively.

[0007] The movable comb electrodes 11a extending from the vibrating weights 11 and 12 in a non-contact manner between the fixed comb electrodes 3a and 4a.
12a are respectively formed. These vibration weights 11,
Reference numeral 12 is supported by the fixed electrodes 5 and 6 via the outer movable beam 8a, the inner movable beam 9a and the fixed beam 7 so as to be freely vibrated.

An electrode 11b is formed on the bottom surface of the concave portion 2 below the vibration weight 11, and the vibration weight 11 and the electrode 11
and a capacitor is formed with the capacitor b.

Further, an electrode 12b is formed on the bottom surface of the concave portion 2 below the vibrating weight 12, and the vibrating weight 12 and the electrode 12 are formed.
and a capacitor is formed with the capacitor b.

Further, the supporting substrate 1a other than the fixed electrodes 3 to 6
Is covered with a silicon thin film 1b.
A slit is provided between the silicon thin film 1b and the fixed electrodes 3 to 6, and these are electrically insulated.

On the silicon thin film 1b formed on the upper surface 1a 'of the support substrate 1a, a lid substrate 1c of the same shape as that of the support substrate 1a and having the concave portion 2 including the depression 2a is formed.
Are joined to face each other.

As a result of this joining, a sealed space 2b is formed which includes an object to be sealed including movable parts such as the vibrating weights 11 and 12 and fixed parts such as the fixed comb electrodes 3a and 4a. This closed space 2b is normally reduced to 1 atm or less in order to reduce the air resistance of the movable parts such as the vibrating weights 11 and 12.

Next, the operation of the angular velocity sensor 20 will be described. An AC voltage is applied between the fixed electrode 3 (4) and the fixed electrode 5 (6) while being superimposed on a DC voltage. Then, the vibrating weights 11 and 12 vibrate at the frequency of the AC voltage in directions opposite to each other in the x-axis direction due to the electrostatic attraction force. This vibration is caused by the outer movable beam 8a and the inner movable beam 9a.
This is made possible by mutual bends. As described above, when the vibrating weights 11 and 12 are vibrating and the angular velocity sensor 20 is rotated about the y-axis connecting the fixed beams 7 and 7, the vibrating weights 11 and 12 receive Coriolis force due to the rotational force. T
Vibration also occurs in the up-down direction in the axial direction. Due to this vibration, the capacitance formed between the vibration weight 11 and the electrode 11b and the capacitance formed between the vibration weight 12 and the electrode 12b change differentially. Angular velocity can be obtained by utilizing the Coriolis force by voltage-converting and amplifying differentially the change capacitance of these capacitances. In order to take out the capacitance, the substrate 1a,
Means such as a via hole provided in 1c are used.

[0014]

However, the conventional angular velocity sensor 20 as an electronic component has a closed space 2 in order to reduce the air resistance of the movable portion and improve the detection sensitivity.
b is reduced to 1 atm or less. Thus, the closed space 2
When the pressure b is reduced, there is a concern that the supporting substrate 1a and the lid substrate 1c as the outer casing of the closed space 2b may be deformed or destroyed by being pushed by the atmospheric pressure indicated by the dashed arrow in FIG. The thickness of the lid substrate 1c has to be increased. For this reason, electronic components such as the angular velocity sensor 20 have become thicker and have a larger shape.

Therefore, the present invention aims to reduce the thickness and
An object of the present invention is to provide an electronic component having improved strength against external pressure such as atmospheric pressure.

[0016]

According to the first aspect of the present invention, there is provided an electronic component having a sealed space between two substrates, the sealed space being reduced to an atmospheric pressure or less, and an object to be sealed is accommodated in the sealed space. And at least one support for supporting the two substrates between the two substrates in the closed space.

According to the present invention, since the support for supporting at least one of the substrates is provided between the two substrates (the support substrate and the lid substrate) forming the closed space which is reduced in pressure, the external pressure such as the atmospheric pressure is provided. Accordingly, the one substrate does not dent into the closed space. Therefore, the present invention can reduce the thickness of at least one of the substrates constituting the external housing,
A thin electronic component can be realized, and the strength against external pressure can be improved.

The closed space in the present invention can be formed by providing a concave portion in one or both of the substrates. In addition, the sealing object is formed by processing a thin film member such as silicon interposed between two substrates with a functional element for detecting a physical quantity or a device for performing a functional operation, or by processing another material. Formed. The support is also formed of two substrates and a thin film member or another material.

The invention according to claim 2 is an electronic component,
A sealed space is formed by facing two recessed substrates with their recessed sides facing each other, and a functional element having at least a movable portion disposed in the sealed space is formed between the substrates, and between the bottom surfaces of the recessed portions of the two substrates. And at least one support for supporting the bottom surfaces of the two substrates at a position where the operation of the recess is not hindered.

In the present invention, the thickness of the bottom surface portion of the concave portion of at least one substrate is smaller than that of the other portion. Therefore, when the pressure in the closed space is reduced, the bottom surface of the concave portion tends to be recessed due to the atmospheric pressure. However, since the bottom surface portion is supported from the inside of the closed space by the support, it does not dent into the inside.

Further, when the pressure in the closed space is made equal to or lower than the atmospheric pressure, the viscous resistance of the air acting on the movable portion is reduced, and the operation of the movable portion becomes quick. The support is provided at a position that does not hinder the operation of the movable part, and the support may be planted at a site using a space provided in the surface of the movable part. Providing a plurality of supports increases the force for supporting the bottom surface of the concave portion.

The invention according to claim 3 is an electronic component according to the present invention,
The support is made of the same material as the substrate.

In the present invention, since the support is made of the same material as both substrates, when forming the recesses in both substrates, a part of the material of both substrates is left as the support. The support can support at least one substrate against external pressure such as atmospheric pressure.

According to a fourth aspect of the present invention, there is provided an electronic component comprising:
The support has a three-layer structure of glass, silicon and glass.

According to the present invention, when both substrates are glass and the functional element forming material is silicon, when forming the upper and lower support portions with the glass of both substrates and forming the movable portion with the functional element forming material silicon, A part of silicon is left as an intermediate support part, so that a support having a three-layer structure can be formed. The substrate can support the substrate against external pressure such as atmospheric pressure.

According to a fifth aspect of the invention, there is provided an electronic component manufacturing method, wherein a concave portion is formed in each of two substrates, and at least one supporting portion is respectively implanted on a bottom surface of the concave portion. A step of providing a thin film member on the surface of the substrate where the concave portion is formed, and processing the thin film member to form a functional element having a movable portion in the region of the concave portion,
A step of leaving a part of the thin film member on the distal end surface of the support portion, and a step of overlapping and joining the other substrate to the thin film member so that the concave portion and the support portion of the two substrates face each other. Things.

According to the present invention, when a thin film member such as silicon is bonded to one of the substrates, the thin film member is supported by the supporting portion and does not dent into the concave portion of the substrate, and can maintain a uniform flat surface. High-accuracy photolithography can be realized for element processing.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An angular velocity sensor 10 will be described below with reference to FIG. 1 as an embodiment of an electronic component according to the present invention.

Since the present embodiment relates to an improvement of the conventional angular velocity sensor 20 shown in FIG. 10, the same parts as those of the conventional angular velocity sensor 20 are denoted by the same reference numerals, and the description is used.

In FIG. 1 and FIG. 9, reference numeral 13b denotes an intermediate support formed on the lower support 13a.
It is made of the same silicon material as the silicon thin film 1b that forms the movable portions such as 1 and 12 and the fixed portions such as the fixed electrodes 3 to 6. As shown in FIG. 2, a plurality of lower support portions 13a are planted on the bottom surface of the concave portion 2 of the support substrate 1a, and the outer movable beam 8a, the inner movable beam 9a, and the vibrating weight 11,
12 and the like, which are provided so as not to contact the movable portion 10a. That is, it is formed in the space between the outer movable beam 8a and the inner movable beam 9a of the movable portion 10a or in the space between the vibrating weights 11 and 12.

In FIG. 2, seven lower support portions 1 are provided.
Although 3a are provided in a distributed manner, one may be provided at the center of the concave portion 2 which is most effective for supporting the external pressure. The lower support portion 13a may have any shape such as a cylinder, a prism, or a trapezoid as long as it does not deform under atmospheric pressure unless it comes into contact with the movable portion 10a.

The silicon thin film 1b formed on the surface 1a 'of the supporting substrate 1a including the concave portion 2 and the concave portion 2a shown in FIG.
A lid substrate 1c having the same shape as the support substrate 1a
However, as shown in FIG. 9, the concave portions 2 and 2 and the lower support portion 13a and the upper support portion 13c are joined to face each other.
Then, the closed space 2c that protects the movable portion 10a and the like is formed by the support substrate 1a and the concave portions 2 and 2 including the depressions 2a and 2a of the lid substrate 1c with the silicon thin film 1b interposed therebetween.

The lower support portion 13a formed in the concave portion 2, the upper intermediate support portion 13b, and the upper support portion 13c of the lid substrate 1c
Means that the support 13 has a three-layer structure. The support 13 is interposed between the support substrate 1a and the lid substrate 1c in the closed space 2c, and
c functions to support the support substrate 1a and the lid substrate 1c with each other so that c does not dent or deform into the interior due to external pressure such as atmospheric pressure. The support 13 shown in FIG. 9 is formed of a three-layer structure of glass, silicon, and glass as described above in a semiconductor microfabrication process of a semiconductor material.
Another structural material such as a single piece of silicon, glass, or metal may be formed by depositing or bonding on the bottom surface of the recess 2.

As the supporting substrate 1a and the lid substrate 1c, a material capable of highly airtight bonding can be appropriately selected from a glass substrate, an insulating material such as a silicon substrate, a conductive material such as a metal, and the like. Is also good.

The materials constituting the functional element include:
In addition to silicon, a metal or the like can be used, and any material can be used as long as it can form a movable portion that can be mechanically operated under reduced pressure. This is selected in consideration of the materials of the above-described support substrate 1a and lid substrate 1c.

The operation of the angular velocity sensor 10 of this embodiment is the same as that of the conventional angular velocity sensor 20 shown in FIGS.

Next, a method of manufacturing the angular velocity sensor 10 of the present embodiment will be described with reference to FIGS. In FIG. 3, a Pyrex glass substrate 2 having a thickness of 400 μm
Prepare 1 In FIG. 4, a Pyrex glass substrate 21 is processed by photoetching to form a support substrate 1a. As shown in FIG. 2, the support substrate 1a provides a free vibration space of the movable portion of the angular velocity sensor 10 at a central portion on the upper surface side.
It has a recess 2 of 0 μm. A plurality of lower support portions 13 a having a height from the bottom surface of 50 μm and a cross section of 200 μm are formed in the recess 2 by partially leaving the Pyrex glass substrate 21 when the recess 2 is formed.

Next, using a photolithography method,
Electrodes 11b and 12b made of a metal film such as aluminum (Al) or gold (Au) / chromium (Cr) are formed on the bottom surface of the recess 2 by a sputtering method, a vapor deposition method, or the like.

In FIG. 5, a silicon substrate 22 having the same size as the support substrate 1a and a thickness of 300 μm is prepared. Then, the upper surface 1a 'of the support substrate 1a on the concave portion 2 side and the tip surface of the lower support portion 13a are anodically bonded to the silicon substrate 22. In this anodic bonding, in an atmospheric pressure atmosphere of 1 atm, the substrate temperature of the support substrate 1a and the silicon substrate 22 is set to 400 ° C., the support substrate 1a is set to the cathode side, and the silicon substrate 22 is set to the anode side. This is performed by applying a DC voltage of When the temperature of the closed concave portion 2 formed by the anodic bonding returns to normal temperature, the pressure becomes 1 atm or less.

In FIG. 6, the silicon substrate 22 is etched with an aqueous solution of potassium hydroxide (KOH) to have a thickness of 2
It is processed into a thin film member such as a 0 μm silicon thin film 1b.
The silicon thin film 1b tries to be recessed into the recess 2 due to the atmospheric pressure, but is maintained by the lower support portion 13a without being recessed and maintains a uniform plane.

A positive photoresist is applied on the silicon thin film 1b. The photoresist is exposed and developed using a positive photomask having a planar shape of the functional element of the angular velocity sensor 10 shown in FIG.
A resist mask having the shape of the functional element shown in FIG.

As shown in FIG. 7, RIE is performed using the above-mentioned resist mask and sulfur hexafluoride (SF ₆ ) gas.
(Reactive ion etching), silicon thin film 1b
Is dry-etched. Then, the unnecessary resist mask is removed by oxygen O ₂ ashing to form the functional element of the angular velocity sensor 10 shown in FIG. That is, the movable portion 10a such as the outer movable beam 8a, the inner movable beam 9a, the movable weights 11 and 12, and the fixed portions such as the fixed electrodes 3 to 6 are formed, and at the same time, the silicon thin film 1b is formed on the upper end surface of the lower support portion 13a. The intermediate support portion 13b is formed leaving the portion.

In FIG. 8, a Pyrex glass substrate is processed by photoetching to form a lid substrate 1c having a concave portion 2, an upper support portion 13c, and the like so as to have a plane symmetrical shape with respect to the support substrate 1a. Then, the supporting substrate 1a and the lid substrate 1c face each other on the concave side, that is, the concave 2
The lid substrate 1c and the silicon thin film 1b are bonded by anodic bonding, with the lower support portion 13a and the upper support portion 13c facing each other. This anodic bonding is performed, for example, in a vacuum chamber having a degree of vacuum of 10 Pa in addition to the conditions for anodic bonding between the support substrate 1a and the silicon substrate 22.

In FIG. 9, the recess 2 of the supporting substrate 1a and the recess 2 of the lid substrate 1c are joined via the silicon thin film 1b by this anodic bonding, and the depressurized closed space 2c
Is formed. In the closed space 2c, a lower support 13a of the support substrate 1a, an intermediate support 13b which is a part of the silicon thin film 1b, and an upper support 1 of the lid substrate 1c.
A support 13 having a three-layer structure 3c is formed. The support 13 prevents the support substrate 1a or the lid substrate 1c from being recessed into the closed space 2c due to an external pressure such as the atmospheric pressure. The upper support portion 13c of the lid substrate 1c and the intermediate support portion 13b of the silicon thin film 1b are preferably joined, but may not be completely joined if they are in contact.

According to the present invention, the thickness of the angular velocity sensor 10 shown in FIG.
It can be 8 mm. The thickness of the conventional angular velocity sensor 20 shown in FIG. 11 needs to be 2.0 mm in order to maintain the strength against the atmospheric pressure. Therefore, the present invention
An electronic component having a thickness of about 40% as compared with a conventional electronic component can be realized.

[0046]

According to the invention relating to the electronic components according to the first to fourth aspects, the two substrates constituting the closed space are supported from the inside by the support, so that the two substrates as the outer casing are provided. At least one of them can be made thinner, so that the overall thickness and size can be reduced, and the strength against external pressure such as atmospheric pressure can be improved.

In particular, when the two substrates are a supporting substrate and a lid substrate, and the material of the support is a material of the supporting substrate and the lid substrate and a material for forming the object to be sealed, the supporting substrate, the lid substrate and the object to be sealed are formed. When an object is formed, each support portion serving as a support having a three-layer structure can be formed at the same time, thereby simplifying the process.

According to a fifth aspect of the present invention, when a thin film member such as silicon is bonded to one of the substrates, the thin film member is supported by the supporting portion and is depressed by atmospheric pressure. Since a uniform flat surface can be maintained without being depressed inward, highly accurate photolithography can be performed, and an electronic component having a fine structure can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view of a support substrate and a functional element of an angular velocity sensor according to an embodiment of the present invention, excluding a cover substrate.

FIG. 2 is a perspective view of a support substrate.

FIG. 3 is a cross-sectional view taken along the line XX of FIG. 1 illustrating a method of manufacturing an angular velocity sensor according to an embodiment of the electronic component of the present invention, and is a process chart for preparing a Pyrex glass substrate to be processed into a support substrate.

FIG. 4 is a process diagram of forming a support substrate by processing a Pyrex glass substrate.

FIG. 5 is a process diagram of anodically bonding a silicon substrate to an upper surface of a support substrate.

FIG. 6 is a process diagram for thinly polishing a silicon substrate.

FIG. 7 is a process diagram of etching a silicon substrate into a functional element shape of an angular velocity sensor.

FIG. 8 is a process chart of disposing a lid substrate processed into the same shape as the support substrate on a silicon thin film formed on the support substrate.

FIG. 9 is a cross-sectional view of the completed angular velocity sensor of the present embodiment obtained by anodically bonding the lid substrate and the silicon thin film.

FIG. 10 is a plan view of a supporting substrate and a functional element of the angular velocity sensor as a conventional electronic component, excluding a lid substrate.

11 is a sectional view taken along line YY of FIG.

[Explanation of symbols]

 1a Support substrate 1a 'Surface of support substrate including concave portion 1b Silicon thin film 2 Recess 2a Depressed 3-6 Fixed electrode 3a, 4a Fixed comb-tooth electrode 7 Fixed beam 8a Outer movable beam 9a Inner movable beam 10 Angular velocity sensor 10a Movable portion 11, DESCRIPTION OF SYMBOLS 12 Vibration weight 11a, 12a Movable comb-teeth electrode 11b, 12b Electrode 13 Support 13a Lower support 13b Intermediate support 13c Upper support 21 Pyrex glass substrate 22 Silicon substrate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F055 AA40 BB20 CC12 CC51 DD05 DD07 EE25 FF23 FF43 GG01 GG12 4M112 AA02 BA07 CA26 CA36 DA04 DA15 DA18 EA02 EA13

Claims (5)

[Claims] An airtight space is provided between two substrates, the airtightness being reduced to an atmospheric pressure or less, an object to be sealed is housed in the airtight space,
An electronic component, comprising: at least one support for supporting the two substrates between the two substrates in the closed space. 2. A closed space is formed by facing two recessed substrates with their recesses facing each other, and a functional element having at least a movable portion disposed in the closed space is formed between the substrates. An electronic component, comprising: at least one support that supports the bottom surfaces of the two substrates at a position between the bottom surfaces of the concave portions of the substrate that does not hinder the operation of the functional element. 3. The electronic component according to claim 1, wherein the support is formed of the same material as the substrate. 4. The electronic component according to claim 1, wherein the support has a three-layer structure of glass, silicon, and glass. 5. A step of forming a concave portion on each of two substrates and implanting at least one supporting portion on a bottom surface of each of the concave portions, and a step of providing a thin film member on a surface of the one substrate on which the concave portion is formed. And processing the thin film member to form a functional element having a movable portion in the region of the concave portion,
A step of leaving a part of the thin film member on the distal end surface of the support portion, and a step of overlapping and joining the other substrate to the thin film member so that the concave portion and the support portion of the two substrates face each other. Manufacturing method of electronic components.