JPH10206455A - Manufacture for pressure-reduced sealed electronic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a pressure-reduced sealed electronic part whereby a degree of vacuum can be adjusted, by projecting laser beams to a getter film. SOLUTION: A supporting substrate 11 and a sealing substrate 12 are anodically bonded, thereby forming a cavity 14 storing a function part 10, a gutter chamber 15 where a gutter film 17 is formed and a channel 16 connecting the cavity and gutter chamber. A laser beam 18 is projected from outside of the supporting substrate 11 and sealing substrate 12 to the gutter film 17. As a result, the gutter film 17 is heated and evaporated, and at the same time reacts to be oxidized with a residual gas. The residual gas in the cavity 14 is accordingly reduced, whereby a degree of vacuum is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a vacuum-sealed electronic component, such as an acceleration sensor, an angular velocity sensor, and a vacuum manometer, in which a functional section must be maintained under reduced pressure.

[0002]

2. Description of the Related Art In a conventional method of manufacturing a pressure-reduced sealed electronic component such as an angular velocity sensor, Sensors and Ac
The vacuum sealing method described in tuators A. 43 (1994) 243-248) will be described with reference to FIGS.

In FIG. 7, a silicon substrate 21 is thinned to form a diaphragm 21a having a strain gauge as a functional part and a vacuum chamber 21b. Further, a gas vent hole 21c is formed in the silicon substrate 21. The gas vent hole 21c is connected to a vacuum chamber 21b through a channel 21d.

On the other hand, 22 is a Pyrex glass substrate,
Bonded to the silicon substrate 21 by anodic bonding. Next, in a sealing step performed in the vacuum chamber, the gas in the vacuum chamber 21b is discharged from the gas vent hole 21c into the vacuum chamber. Thereafter, the gas vent hole 21c is sealed with a metal such as aluminum 23 by CVD (chemical vapor deposition), vapor deposition, or the like, and the vacuum chamber 21b is sealed at a predetermined degree of vacuum.

In the vacuum sealing method shown in FIG. 8, similarly to the vacuum sealing method shown in FIG. 7, the silicon substrate 24 is thinned to form a functional portion comprising a diaphragm 24a and a vacuum chamber 24b. A getter chamber 24c is formed which communicates with the vacuum chamber 24b via the channel 24d. Then, with the non-evaporable solid getter material 25 sealed in the getter chamber 24c, the silicon substrate 24 and the Pyrex glass substrate 26 are anodically bonded. During this anodic bonding, oxygen gas is generated from the bonding surface, and a part thereof is
Flows into. The getter material 25 is activated at a temperature of about 400 ° C. during anodic bonding, adsorbs the gas flowing into the vacuum chamber 24b, and seals the vacuum chamber 24b under reduced pressure.

[0006]

However, according to the conventional method for manufacturing a reduced-pressure sealed electronic component shown in FIG. 7, the gas vent hole 21c provided in the silicon substrate 21 is formed by ultrasonic processing, sand blasting, or the like. The unevenness of the inner wall surface becomes large, and a thin film formed by CVD or vacuum deposition cannot be completely and reliably sealed. Further, the decompression-sealed electronic component manufactured by the conventional manufacturing method has a drawback that the shape becomes large because it has the gas vent hole 21c having a structure for sealing from the outside.

Furthermore, in the conventional method for manufacturing a vacuum sealed electronic component shown in FIG. 8, a getter chamber for accommodating a solid getter material of several mm square is provided, so that the size of the manufactured electronic component becomes large. . In addition, there is a concern that the support substrate and the sealing substrate may be bonded poorly due to dust from the getter material.

Accordingly, an object of the present invention is to provide a method of manufacturing a vacuum sealed electronic component capable of adjusting the degree of vacuum by irradiating a getter film with a laser beam.

[0009]

According to a first aspect of the present invention, at least one of a concave portion and a functional portion is formed in at least one of a support substrate and a sealing substrate for sealing the support substrate. A cavity for forming a getter film on at least one of the support substrate and the sealing substrate, joining the support substrate and the sealing substrate, and storing the functional unit and the getter film by the recess. And heating and evaporating the getter film with a laser beam passing through at least one of the supporting substrate and the sealing substrate, and reacting the getter film with a residual gas to seal the cavity under reduced pressure.

According to the present invention, a getter film made of an active metal formed in a cavity is irradiated with a laser beam from the outside to heat and evaporate the getter film. During this evaporation, the atoms of the getter film react with the residual gas to generate a compound, and in particular, react with oxygen gas to generate an oxidized compound. Thus, the getter film is evaporated by the irradiation of the laser beam and reacts with the residual gas in the cavity to reduce the residual gas in the cavity. Thereby, the degree of vacuum in the cavity is increased. The compound generated by the evaporation of the getter film adheres to the inner wall of the cavity or the functional part. The functional unit may be formed of an element such as a strain gauge which is less affected even if a compound accompanying evaporation is attached, and which is not likely to be short-circuited by being covered with a passivation film or the like.

According to a second aspect of the present invention, at least one of a supporting substrate and a sealing substrate on which a functional portion is formed has a plurality of concave portions partitioned by partition walls.
Forming a groove connecting the recesses, forming a getter film on at least one of the support substrate and the sealing substrate, joining the support substrate and the sealing substrate, and providing the function Forming a cavity for accommodating a portion and a getter chamber provided with the getter film, forming a channel communicating between the cavity and the getter chamber by the groove, and forming at least one of the support substrate and the sealing substrate. The getter film is heated and evaporated with a laser beam passing through the substrate, and is reacted with a residual gas to seal the cavity under reduced pressure.

According to the present invention, a getter film formed of an active metal formed in a getter chamber is irradiated with a laser beam from the outside to heat and evaporate the getter film. During this evaporation, the atoms of the getter film react with the residual gas to generate a compound, and in particular, react with oxygen gas to generate an oxidized compound. As described above, the getter film is evaporated by the irradiation of the laser beam, combines with the residual gas in the cavity, and reduces the residual gas in the cavity. Thereby, the degree of vacuum in the cavity is increased. The compound generated as the getter film evaporates adheres to the inner wall surface of the getter chamber. Since the cavity is separated from the getter chamber by a partition wall, the flying of the compound due to the evaporation does not reach the cavity. Therefore, even if the functional unit has the movable part, it does not affect the operation.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for manufacturing a vacuum sealed electronic component according to the present invention will be described with reference to the drawings.

In FIG. 1A, reference numeral 12 denotes a sealing substrate made of Pyrex glass.
, Two concave portions 14a and 15a are formed. A groove 16a having a width and a depth of several μm to several tens μm, each of which communicates the recesses 14a and 15a, is provided on the back surface of one base of the partition wall 13. Also,
A getter film 17 made of an easily oxidizable active metal such as titanium (Ti) or barium (Ba) is formed in a plane shape by vapor deposition or the like on the top surface of the concave portion 15a and away from the groove 16a. .

In FIG. 1B, reference numeral 11 denotes a support substrate made of silicon, and an angular velocity sensor 10 is provided on one side of its surface.
It is formed using semiconductor fine processing technology. Next,
The angular velocity sensor 10 will be described with reference to FIG.

The angular velocity sensor 10 detects the Coriolis force to detect the angular velocity. Reference numeral 1 denotes a rectangular plate-shaped vibrating body, and movable handles 2a and 3a extend at right angles and in both directions from both ends in the longitudinal direction. This movable pattern 2
One ends of the U-shaped support beams 6a and 7a are connected to the tips of a and 3a, and the other ends are connected to the fixing portions 6 and 7.
On the outer surfaces of the movable handles 2a, 3a, a plurality of parallel movable comb-tooth electrodes 2b, 3b (point set portions) are formed at right angles. The movable comb electrodes 2b, 3b
A plurality of fixed comb-teeth electrodes 2c and 3c forming a capacitor in opposition to the fixed comb-teeth electrodes 2c and 3c, and fixed electrodes 2d and 3d (white background portions) coupled to these fixed comb-teeth electrodes 2c and 3c at right angles.
It is formed on a substrate (not shown). The movable comb electrode 2b and the fixed comb electrode 2c on the left side of the vibrator 1 and the movable comb electrode 3b and the fixed comb electrode 3c on the right side form the drive electrode units 2 and 3, respectively.

The movable comb electrodes 2b, 3 of the drive electrode sections 2, 3
Since b and the vibrating body 1 are integrally formed of silicon using the semiconductor fine processing technology, their vibration displacements are the same.

A plurality of movable handles 4a, 5a extend in a direction perpendicular to both sides of the vibrating body 1, and movable comb electrodes 4b, 5b (point set portions) are formed on both sides thereof. . In addition, fixed comb-teeth electrodes 4c, 5c forming capacitors in opposition to the movable comb-teeth electrodes 4b, 5b
(White background), fixed patterns 4d, 5 connected to these
d and the fixed electrodes 4e, 5e,
And these extraction electrodes 4f and 5f are formed on a substrate (not shown).

The movable comb electrode 4 on the upper side of the vibrating body 1
b and the fixed comb electrode 4c, and the lower movable comb electrode 5b and the fixed comb electrode 5c constitute detection electrode portions 4 and 5, respectively. Note that the vibrating body 1, the movable patterns 2a, 3
a, 4a, 5a, the U-shaped support beams 6a, 7a, and the movable comb electrodes 2b, 3b, 4b, 5b can freely vibrate while floating from a substrate (not shown).

Next, the operation of the angular velocity sensor 10 shown in FIG. 4 will be described. The movable comb electrode 2b of the drive electrode unit 2
For example, between the movable comb electrode 3b and the fixed comb electrode 3c of the drive electrode section 3 and between the fixed comb electrode 3c and the fixed comb electrode 2c, an AC voltage having a peak value of 0V and a reverse polarity of 5V is applied. Then, the movable comb electrodes 2b and 3b are alternately attracted to the fixed electrodes 2d and 3d by the electrostatic force so as to increase the area of opposition to the fixed comb electrodes 2c and 3c by the electrostatic force, and the vibrating body 1 is moved by X.
Vibrates in the axial direction.

As described above, if the angular velocity sensor 10 rotates about the center axis perpendicular to the paper surface while the vibrating body 1 is vibrating in the X-axis direction, vibration due to Coriolis force appears in the Y-axis direction. Thus, the vibrating body 1 also vibrates in the Y-axis direction. Then, the detection electrode units 4 and 5 on both sides of the vibrating body 1
On the one hand increases and the other decreases. By subjecting the increased / decreased capacitance to voltage conversion and differential amplification, the vibration component in the X-axis direction is removed, the vibration component due to the Coriolis force in the Y-axis direction is extracted, and the rotational angular velocity and its integration are integrated. The angle can be determined.

Next, the joining of the support substrate 11 and the sealing substrate 12 will be described with reference to FIGS.

As shown in FIG. 1, the sealing substrate 12 is superimposed on the supporting substrate 11 so that the angular velocity sensor 10 formed on the supporting substrate 11 is covered by the concave portion 14a of the sealing substrate 12. Then, anodic bonding is performed in a reduced pressure atmosphere of a vacuum chamber. By this anodic bonding, most of the four sides of the sealing substrate 12 and the back surface of the partition wall 13 are bonded to the support substrate 11.

As shown in FIGS. 2 and 3, the angular velocity sensor 1 is formed by a concave portion 14a formed in the sealing substrate 12.
0 is formed, and the cavity 1 is formed.
A getter chamber 15 is formed by 5a, and a channel 16 is formed by a groove 16a formed in the partition wall 13. The channel 16 allows gas to flow into and out of the cavity 14 and the getter chamber 15. Oxygen flows into the cavity 14 and the like due to the anodic bonding, and the degree of vacuum is reduced from the degree of vacuum in the vacuum chamber to about several hundreds to several thousands Pa.

Next, referring to FIG.
4. A method for reducing the residual gas in the getter chamber 15 and the channel 16 (hereinafter, referred to as the cavity 14) will be described.

As described above, the laser beam 18 is applied to the getter film from the outside of the sealing substrate 12 of the reduced-pressure sealed electronic component in which the cavity 14 and the like have a pressure of several hundreds to several thousands Pa by the anodic bonding performed in the reduced-pressure atmosphere. Irradiation is performed on the getter film 17 to heat and evaporate a part of the getter film 17. Getter film 17
When evaporating, the getter film 17 is combined with the residual gas in the cavity 14 and the like, in particular, oxygen gas, and
In the case of i), it becomes titanium oxide (TiO ₂ ), and in the case of barium (Ba), it becomes barium oxide (BaO), which flies on the inner wall surface of the getter chamber 15 as shown by the arrow. The atoms of the getter film 17 that have not collided with the oxygen atoms during the evaporation and have landed on the wall surface of the getter chamber 15 are then combined with, for example, oxygen atoms to form an oxide compound.

As described above, since the getter film 13 evaporates and combines with the residual gas, the residual gas in the cavity 14 and the like is reduced, and the degree of vacuum in the cavity 14 and the like can be improved. The adjustment of the degree of vacuum is performed by the getter film 13.
This is performed by enlarging the area of laser irradiation on the substrate.
The evaporation of the getter film 17 is performed such that the getter film 17 scatters on the wall surfaces of the surrounding getter chambers, as indicated by arrows, so that the scattering of the atoms of the getter film 17 is carried out in the cavity 14 partitioned by the partition wall 13. Not reachable.

As the laser device used in this embodiment,
A YAG laser device that emits laser light in the visible light range that transmits through the sealing substrate 12 made of Pyrex glass or the like is used. Further, the getter film 17 is formed on the support substrate 1.
1 may be formed. Further, the support substrate forming the functional unit such as the angular velocity sensor 10 may be Pyrex glass. In this case, silicon and silicon oxide are deposited on a Pyrex glass support substrate by CVD (Chemical Vapor Deposition) or the like, or a Si substrate is bonded to the Pyrex glass support substrate. The functional part is formed by using this.

The partition wall 13 provided between the getter chamber 15 and the cavity 14 is desirably absent in order to promptly promote the reaction of the getter film 17 with the residual gas accompanying the evaporation of the atoms. Even if there is a partition wall 13, it is desirable that the channel 16 has a large cross section for the above-described reason. However, since the atoms of the getter film 17 are deposited along with the evaporation to prevent a decrease or stop of the function such as a short-circuit failure of the movable part of the electronic component,
A partition wall 13 is required, and a channel having an appropriate size is required.

Therefore, the partition wall having the channel only needs to have a structure that at least protects the movable portion from direct splash due to evaporation of the getter film 17. And even if the channel is bent several times from the getter chamber, it may be connected to the cavity. In the above embodiment,
The partition wall may enlarge a non-movable portion of the functional unit 10, for example, the fixed electrode 2d, form a getter chamber and a cavity with the expanded fixed electrode, and use the gap between the fixed electrodes as a channel.

Next, a case where a vacuum pressure gauge is used for the functional part of the vacuum sealing electronic component will be described with reference to FIG.
Reference numeral 31 denotes a support substrate made of single-crystal silicon, whose central part on the front surface side is removed by etching into a truncated cone shape, and a diaphragm 31a having a thickness of several tens μm is formed on the back surface side. A resistance strain gauge 33 is formed on the back surface of the diaphragm 31a.

Reference numeral 32 denotes a sealing substrate made of Pyrex glass, and a getter film 35 is formed on the back surface thereof in a planar shape.

The support substrate 31 and the sealing substrate 32 are joined by an anodic joining technique to form one cavity 36.
Is formed.

Next, the getter film 35 is irradiated with a laser beam from the sealing substrate 32 side, and a part thereof is heated and melted to evaporate. With this evaporation, the evaporated atoms of the getter film 35 combine with the remaining gas to form a compound and adhere to the inner surface of the cavity 36. By the evaporation of the getter film 35, the cavity 36 is provided with a reference vacuum degree. The atoms evaporated from the getter film 35 also adhere to the diaphragm 31a, but their weight is extremely small compared to the pressure applied to the diaphragm 31a.
There is no problem in using it as a vacuum manometer.

In the above embodiment, the angular velocity sensor and the vacuum manometer are shown as examples of the functional parts. However, the present invention requires that other functional parts having movable parts such as an acceleration sensor be held under reduced pressure. The present invention is applied to a method of manufacturing an electronic component that is not required.

[0036]

According to the first and second aspects of the present invention,
A laser beam is applied to the evaporable getter film formed in the getter chamber from the outside to evaporate the getter film. During this evaporation, the atoms of the getter film chemically react with the residual gas to produce a compound, especially an oxidized compound. Due to this evaporation and chemical reaction, residual gas in the cavity, especially oxygen gas, is reduced. Then, the degree of vacuum in the cavity is increased.

The degree of vacuum of the cavity can be adjusted by adjusting the irradiation area of the laser beam to the getter film.

Further, the invention described in both claims does not use a non-evaporable solid bulky getter material as in the prior art,
Since a getter film made of an active metal that is tens to hundreds of times thinner than the getter material and can be formed into an arbitrary planar shape is used, the reduced-pressure sealed electronic component to be manufactured is small. In particular, the first aspect of the present invention does not include a dedicated getter chamber, so that the size can be further reduced.

Further, according to the inventions described in both claims, unlike the conventional case, it is not necessary to provide a gas vent hole in order to increase the degree of vacuum in the cavity. be able to.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a method of manufacturing a reduced-pressure sealed electronic component according to the present invention, in which A is a perspective view of a sealing substrate on which a concave portion and a getter film are formed, and B is a supporting substrate on which an angular velocity sensor is formed. Perspective view

FIG. 2 is also a process diagram of anodically bonding a supporting substrate and a sealing substrate.

3 is a sectional view taken along line XX of FIG. 2;

FIG. 4 is a plan view of an angular velocity sensor as a functional unit similarly shown in FIGS.

FIG. 5 is also a process diagram in which the getter film is heated and evaporated by a laser beam, and the residual gas is reduced by an oxidation reaction with the residual gas.

FIG. 6 is a view showing another embodiment of the method for manufacturing a reduced-pressure sealed electronic component according to the present invention, and is a manufacturing process diagram of a reduced-pressure sealed electronic component having a cavity also serving as a getter chamber.

FIG. 7 is a morphological view showing a conventional method for manufacturing a vacuum sealed electronic component.

FIG. 8 is a morphological view showing another conventional method for manufacturing a vacuum sealed electronic component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillator 2, 3 Drive electrode part 2a, 3a, 4a, 5a Movable handle 2b, 3b, 4b, 5b Movable comb electrode 2c, 3c, 4c, 5c Fixed comb electrode 2d, 3d Fixed electrode 4, 5 Detection electrode Part 4d, 5d Fixed pattern 4e, 5e Fixed electrode 4f, 5f Extraction electrode 6, 7 Fixed part 6a, 7a U-shaped support beam 10 Angular velocity sensor 11, 31, Support substrate 12 Sealing substrate 13 Partition wall 14, 36 Cavity 15, Getter chamber 16 Channel 17, 35 Getter film 18, 37 Laser beam 31a Diaphragm 33 Strain gauge 34 Passivation film

Claims (2)

[Claims] At least one of a concave portion and a functional portion is formed in at least one of a support substrate and a sealing substrate that seals the support substrate, and at least one of the support substrate and the sealing substrate is formed. A getter film is formed on one side, and the support substrate and the sealing substrate are joined to form a cavity for accommodating the functional unit and the getter film by the concave portion. A method for manufacturing a vacuum-sealed electronic component, comprising heating and evaporating the getter film with a laser beam passing through at least one of the films and reacting the getter film with a residual gas to seal the cavity under reduced pressure. 2. The method according to claim 1, wherein at least one of the supporting substrate and the sealing substrate on which the functional unit is formed has a plurality of recesses partitioned by partition walls, and a groove connecting the recesses is formed. A getter film is formed on at least one of the substrate and the sealing substrate, the support substrate and the sealing substrate are joined, and the recess is provided with a cavity for accommodating the functional unit and the getter film. Forming a channel that communicates between the cavity and the getter chamber by the groove, and heating the getter film with a laser beam that transmits at least one of the support substrate and the sealing substrate. And evaporating and reacting with a residual gas to seal the cavity under reduced pressure.