JPH10144935A - Manufacturing method of compact electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a compact electronic component that can be further miniaturized by twice performing anode junction and sealing a cavity which accommodates a functional part by the second anode junction. SOLUTION: Using a method, a cavity 13a accommodating a functional part (k) is formed by overlapping the junction surface of a support substrate 1, where the functional part (k) is formed and junction surface of a substrate 2 to be covered with a lid, where a through-hole 2b for degassing is formed at a recessed part 2a to cover the functional part (k) are formed and then performing a first anode junction. A sealing substrate 3 is overlapped to the through-hole 2b of the substrate 2 to be covered with a lid and a second anode junction is performed in vacuum, thus reducing the pressure of the cavity 13a and then closing it.

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 small electronic component such as a gyro sensor, 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 small electronic component such as a gyro sensor, a sensor and an actuator are used as means for reducing and sealing a cavity in which a functional portion is housed.
The vacuum sealing method described in ators A. 43 (1994) 243-248) will be described with reference to FIGS.

In FIG. 8, a silicon substrate 21 is processed to be thin to form a diaphragm 21a having a strain gauge as a functional part and a vacuum chamber 21b. Further, an opening 21c is formed in the silicon substrate 21. The opening 21c is connected to the vacuum chamber 21b via a channel.

On the other hand, 22 is a Pyrex glass substrate,
Bonded to the silicon substrate 21 by anodic bonding. During this anodic bonding, oxygen gas generated from the bonding surface is
1b, the degree of vacuum in the vacuum chamber 21b cannot be set to a predetermined value even if anodic bonding is performed in a vacuum.
The gas flowing into the vacuum chamber 21b is exhausted from the opening 21c into the vacuum chamber, and thereafter, as shown in FIG. It is to be sealed.

Further, the vacuum sealing method shown in FIG. 10 is similar to the vacuum sealing method shown in FIGS.
Is processed to form a diaphragm 24a having a strain gauge as a functional part and a vacuum chamber 24b. Further, a getter chamber 24c communicating with the vacuum chamber 24b through a channel is formed. With the getter material 25 sealed in the getter chamber 24c, the silicon substrate 24 and the Pyrex glass substrate 26 are anodically bonded. The getter material 25 is activated at a temperature of approximately 400 ° C. during anodic bonding, adsorbs oxygen gas flowing into the vacuum chamber 24b, and maintains the vacuum chamber 24b under reduced pressure.

[0006]

However, in the conventional method for manufacturing a small electronic component shown in FIGS. 8 and 9, after the anodic bonding, the opening is sealed by a process different from the anodic bonding process of vapor deposition or sputtering. Since the sealing is performed, there is a disadvantage that the sealing process is complicated.

In the conventional method of manufacturing a small electronic component shown in FIG. 10, an extra getter chamber for accommodating a getter material must be provided, which hinders miniaturization of the small electronic component.

Therefore, according to the present invention, anodic bonding is performed twice,
It is an object of the present invention to provide a method for manufacturing a small electronic component which can prevent a decrease in the degree of vacuum of the cavity and realize a further miniaturization by sealing the cavity accommodating the functional portion by the second anodic bonding.

[0009]

According to the present invention, there is provided a method for bonding a bonding surface of a support substrate having a functional portion formed thereon and a cover substrate having a through hole for venting gas formed in a concave portion which covers the functional portion. The first anodic bonding is performed on the surface to form a cavity for accommodating the functional unit, the sealing substrate is superimposed on the lid-covered substrate, and the second anodic bonding is performed in a vacuum to perform the penetration. The hole is sealed, and the cavity is sealed under reduced pressure.

According to the present invention, in the first anodic bonding, the supporting substrate and the lid-covered substrate are bonded, and in the second anodic bonding, the through-hole of the lid-covered substrate is sealed in a vacuum (under reduced pressure). Seal with a substrate. In the first anodic bonding, the entire periphery of the concave portion of the supporting substrate and the cover-covered substrate becomes a bonding surface, and since this bonding surface is wide, the amount of generated oxygen gas is large, and the amount of oxygen gas flowing into the cavity is large. Also increase.
However, when the first anodic bonding is performed in the vacuum chamber, the oxygen gas flowing into the cavity is discharged to the outside (in the vacuum chamber) through the through hole. Even if the first anodic bonding is performed under normal pressure and oxygen gas remains in the cavity,
This residual gas is discharged into the vacuum chamber in the second anodic bonding performed in the vacuum chamber.

In the second anodic bonding, the area around the through hole having a diameter of several tens to several hundreds μ is sealed with the sealing substrate by anodic bonding, so that the area of the anodic bonding around the through hole is small, and The amount of oxygen gas generated is also small, and the amount of oxygen gas flowing into the cavity is extremely small, so that the degree of vacuum in the cavity is hardly reduced. In particular, since the width of the sealing substrate is reduced, most of the oxygen gas generated from the bonding surface is released from the periphery of the sealing substrate to the outside.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an angular velocity sensor will be described with reference to the drawings as an example of a small electronic component to which the manufacturing method of the present invention is applied.

1 and 2, reference numeral 1 denotes SOI (Si
A support substrate formed of a substrate (icon on insulator) having a three-layer structure of an active silicon layer s1, a silicon oxide layer s2, and a single crystal silicon layer s3. These thicknesses are, for example, 10 μm for the active silicon layer s1 and 10 μm for the silicon oxide layer s1.
2 is 4 μm, and the single crystal silicon layer s3 is 500 μm. A concave portion 1a is provided on the surface side of the support substrate 1, and a functional portion k shown in FIG. 3 is formed in the concave portion 1a by finely processing the active silicon layer s1.

Reference numeral 2 denotes a cover substrate made of a Pyrex glass substrate having a thickness of 400 μm.
It has a recess 2a of the same size as a. A minute through hole 2b having a diameter of several tens to several hundreds of micrometers is provided on the top surface of the concave portion 2a. The supporting substrate 1 and the lid-covered substrate 2 are bonded together at the bonding surface 1c (2c) by anodic bonding, and a cavity 13a is formed by the concave portion 1a of the support substrate 1 and the concave portion 2a of the lid-covered substrate 2.

Reference numeral 3 denotes a rectangular parallelepiped sealing substrate made of silicon, which seals the periphery of the through hole 2b of the cover substrate 2 by anodic bonding.

Next, the structure of the functional unit of the angular velocity sensor will be described with reference to FIG. This angular velocity sensor detects the Coriolis force to detect the angular velocity. Reference numeral 4 denotes a rectangular plate-shaped vibrator. On both side surfaces of the vibrating body 4, a plurality of movable comb-teeth electrodes 4a (point-set portions) formed in a plurality of movable patterns extending in a perpendicular direction are provided. Also, a plurality of fixed comb-teeth electrodes 5a (white portions) forming a capacitor opposing the movable comb-teeth electrodes 4a are provided. These fixed comb-tooth electrodes 5a are connected to the fixed base 5 via fixed handles.

Further, both ends in the longitudinal direction of the vibrating body 4 extend to both sides thereof in a right angle direction to form movable bases 4b, and these movable bases 4b are formed into a plurality of movable handles extending in a right angle direction. A plurality of movable comb-tooth electrodes 4c (point set portions). Further, a fixed comb-teeth electrode 6a forming a capacitor in opposition to the movable comb-teeth electrode 4c
A plurality of (white portions) are also provided. These fixed comb-teeth electrodes 6a are connected to the fixed base 6 via a fixed handle.

Further, both ends of the vibrating body 4 are connected to a movable base 4b.
And are supported by the fixing portion 8 via a U-shaped support beam 7.

The function part k of this angular velocity sensor has the above-mentioned configuration. Of the function parts k, those indicated by the point set part constitute the movable part, and those indicated by the white part constitute the fixed part. . The functional section k is formed by using a semiconductor fine processing technique such as a lithography technique and an etching technique. In particular, a movable portion indicated by a point set portion has a silicon oxide layer (sacrifice layer) s2 (see FIG. 2) below and around the movable portion ) Is removed by etching to form a free vibration.

Next, the operation of the function section k of the angular velocity sensor shown in FIG. 3 will be described. An alternating voltage of opposite phase is applied to the comb electrodes 4c and 6a. Then, the vibrating body 4 vibrates in the X-axis direction because the movable comb electrode 4c is attracted toward the fixed comb electrode 6a by electrostatic force or the suction is released.

As described above, if the angular velocity sensor rotates about the Z-axis perpendicular to the paper surface while the vibrating body 4 is vibrating in the X-axis direction, vibration due to Coriolis force appears in the Y-axis direction. The vibrator 4 vibrates in the Y-axis direction. Then, the capacitance between the movable comb electrode 4a and the fixed comb electrode 5b on both sides of the vibrating body 4 increases on one side and decreases on the other side of the vibrating body 4. The rotational angle can be obtained by utilizing the Coriolis force by voltage-converting and differentially amplifying the difference in the capacitance.

Next, a method of manufacturing an angular velocity sensor as a small electronic component will be described with reference to FIG. FIG.
In the figure, reference numeral 11 denotes a wafer made of an SOI substrate, as shown in FIG. 2, an active silicon layer s1 and a silicon oxide layer s2.
And a three-layer structure of a single crystal silicon layer s3. These thicknesses are as described above. The SOI substrate 11 has a plurality of recesses 1a formed therein.
Although not shown in FIG. 3A, a functional part k shown in FIG. 3 is formed by processing the active silicon layer s1. That is, as shown in FIG. 2, the functional unit k includes an active silicon layer s1.
Is vertically processed by RIE (Reactive Ion Etching) using an etching gas such as sulfur hexafluoride (SF ₆ ). The movable portion is formed of a silicon oxide layer (sacrifice layer) s under and around the movable portion.
2 is formed so as to be freely vibrable by etching away. The unprocessed surface of the wafer 11 is the bonding surface 1
1c is formed.

In FIG. 4A, reference numeral 12 denotes a wafer for a lid-covered substrate made of Pyrex glass, in which a plurality of recesses 2a shown in FIGS. 1 and 2 are formed. A micro through hole 2b of 100 μm is formed. The unprocessed back surface of the wafer 12 is the bonding surface 1
2c is formed.

The wafer 12 serving as the cover substrate 2 is placed on the wafer 11 serving as the support substrate 1 processed as described above, and the recess 1 a of the wafer 11 and the bonding surface 11 c are connected to the recess 2 of the wafer 12.
a and the first anodic bonding is performed so as to overlap with the bonding surface 12a, respectively, as shown in FIG. 5B.
A composite wafer 13 is formed. Then, the cavity 13a is formed by the concave portion 1a of the wafer 11 and the concave portion 2a of the wafer 12.
(1a, 2a) is formed. This cavity 13a
Has a through hole 2b in the top surface.

Next, as shown in FIG. 5A, a wafer 14 serving as a sealing substrate made of a silicon substrate is prepared. The sealing substrate 3 shown in FIGS. 1 and 2 is formed on the wafer 14 in a lattice shape using lithography and RIE. A through hole 14a is provided between the diagonal bars (sealing substrate 3) of the lattice.
It has become. The bars (sealing substrate 3) of this lattice are arranged so as to come into contact with the through holes 2b when the wafer 14 is overlaid on the composite wafer 13. The wafer 14 having the above-described shape is placed on the composite wafer 13 such that the grid bar (sealing substrate 3) is positioned on the through hole 2b of the composite wafer 13 (wafer 12), and the vacuum chamber A second anodic bonding is performed in the inside to form a composite wafer 15 as shown in FIG. Next, the composite wafer 15 is diced to collectively produce a plurality of small electronic components including individual angular velocity sensors as shown in FIG.

In the second anodic bonding, the composite wafer 15 is placed in a vacuum chamber and the vacuum chamber is evacuated. When the degree of vacuum increases, the cavity 13a communicates with the outside through the through-hole 2b. So that the degree of vacuum is the same as that of the vacuum chamber. Then, the through hole 2b is sealed by the wafer 14 by anodic bonding. Oxygen gas generated at this time flows into the cavity 13a because the opening of the through hole 2b is extremely small and the surrounding bonding area is very small. The amount to be performed is extremely small, and the decrease in the degree of vacuum of the cavity 13a is not so significant as to cause a problem. Most of the oxygen gas generated during the anodic bonding is released from the through-holes 14a of the wafer 14 into the vacuum layer.

The wafer 1 for a sealing substrate shown in FIG.
4 is a lattice-shaped bar (sealing substrate 3), but may be a wafer 16 having a plurality of projections 16a (sealing substrate 3) on the back surface as shown in FIG. The tip area of the protrusion 16a is formed slightly larger than the size of the opening of the through hole 2b of the wafer 12. In FIG. 5, the wafer 16 is replaced with the wafer 12 for the lid covered substrate in FIG.
(Wafer 13)
b is sealed with the projection 16a (sealing substrate 3).

In the above embodiment, a method of manufacturing an angular velocity sensor has been described. However, the present invention can be applied to a method of manufacturing a small electronic component such as a pressure gauge.

[0029]

According to the present invention, anodic bonding is performed in two stages. The first is the same main bonding between the silicon substrate and the Pyrex glass substrate as in the conventional case, and the second is the sealing bonding of the through holes for gas release.

In the second anodic bonding, the bonding area around the minute through hole is small, so that the amount of generated oxygen gas is small, and the amount of oxygen gas flowing into the cavity is extremely small. Hardly lowers the degree of vacuum inside. In particular, since the width of the sealing substrate is reduced, most of the oxygen gas generated from the bonding surface is released to the outside from the periphery of the sealing substrate and does not flow into the cavity.

In the present invention, the main bonding between the supporting substrate and the lid-covered substrate and the sealing bonding between the lid-covered substrate and the sealing substrate are performed only in the anodic bonding step. The manufacturing process is simplified as compared with the case where sealing is performed in a physical vapor deposition process such as sputtering, which is performed in a bonding process.

Further, according to the present invention, since a getter chamber or the like is not required for the reduced-pressure sealing structure as in the related art, the size can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of an angular velocity sensor as one embodiment of a small electronic component manufactured according to the present invention.

FIG. 2 is a partial cross-sectional view taken along line XX of FIG. 1;

FIG. 3 is a plan view of a functional unit of the angular velocity sensor shown in FIGS. 1 and 2;

FIG. 4 shows an embodiment of the manufacturing method according to the present invention.
Process diagram for anodically bonding a 1/2 wafer for a supporting substrate and a 1/2 wafer for a lid covered substrate

FIG. 5 is a process chart of anodically bonding a half wafer for a sealing substrate to the composite wafer shown in FIG. 4 to seal the cavity.

FIG. 6 is also a process diagram of separating a composite wafer into individual angular velocity sensors by dicing.

FIG. 7 is a perspective view of another half wafer for a sealing substrate.

FIG. 8 is a view showing a form in which a functional portion of a conventional small electronic component is sealed.

FIG. 9 is a view showing a form in which the functional part of the small electronic component shown in FIG. 7 is sealed.

FIG. 10 is a view showing a form in which the function part of another conventional small electronic component is vacuum-sealed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 support substrate 1a, 2a concave portion 2 lid covered substrate 2b through hole 3 sealing substrate 4 vibrating body 4a, 4c movable comb electrode 4b movable base 5 fixed base 5a fixed comb tooth electrode 7 U-shaped support beam 8 fixed portion 11 support Wafer for substrate 12 Wafer for lid covered substrate 13, 15 Composite wafer 13a Cavity 14, 16 Wafer for sealing substrate 16a Projection k Function part 1c, 2c Bonding surface s1 Active silicon layer s2 Silicon oxide layer s3 Single crystal silicon layer

Claims (1)

[Claims] 1. A first joining operation of a joining surface of a support substrate on which a functional portion is formed and a joining surface of a lid-covered substrate having a through hole for venting formed in a concave portion covering the functional portion. Forming a cavity for accommodating the functional unit by performing anodic bonding on the sealing substrate on the lid-covered substrate, and performing a second anodic bonding in vacuum to seal the through-hole; The method for producing a small electronic component, wherein