JP2000121468A - Anodic bonding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an anodic bonding method in which air bubbles are not generated, in which it is not required to strip a lattice like conductive thin film and in which a uniform bonding operation can be performed efficiently by a method wherein the lattice like conductive thin film whose pattern is identical to that of the cutting margion of a substrate is formed on a boardlike glass when the substrate is cut so as to be changed into chips. SOLUTION: A conductive thin film 13 is formed on one face of a borosilicate glass 11 to be a film thickness if several hundred to several thousand Å by a sputtering technique or the like, and a lattice like conductive thin film pattern having a width of several tens to several hundred μm is obtained by a photolithographic technique or the like. That is to say, a single-crystal silicon substrate or a metal whose coefficient of thermal expansion is approximate to that of the borosilicate glass such as an Fe-Co-Ni-based alloy or the like is placed on a heater electrode, the borosilicate glass 11 on which the lattice-like conductive thin film 13 is formed is placed, and a needle electrode is brought into contact with the lattice like conductive thin film 13. The substrate is heated to, e.g. 300 to 700 deg.C via the heater electrode, and an anode voltage of 200 to 1000 V is applied to the needle electrode. After a bonding operation, the substrate is cut along the thin film 13 so as to be changed into chips. A lattice width is set at the cutting margin or lower of the substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for anodic bonding of borosilicate glass and a substrate, in particular, there is no generation of bubbles, no need to peel off a conductive thin film, and an efficient uniform bonding can be obtained. It relates to an anodic bonding method.

[0002]

2. Description of the Related Art Borosilicate glass and single crystal silicon substrates are provided with a conductive thin film on one main surface of borosilicate glass.
Next, an anode voltage is applied to the conductive thin film, and the other main surface of the borosilicate glass is bonded to the single crystal silicon substrate by electric field diffusion of alkali ions in the borosilicate glass. In this anodic bonding method, an anodic voltage is applied to the conductive thin film using a needle electrode or a plate electrode. In some cases, the borosilicate glass is not provided with a conductive thin film. As the substrate, a metal having a coefficient of thermal expansion equivalent to that of borosilicate glass can be used, and the conductive thin film may be provided on borosilicate glass via ceramics.

[0003] An example of the bonding of a borosilicate glass and a single crystal silicon substrate by such an anodic bonding method can be found in a pressure sensor used for car electronics and the like. The pressure sensor measures a change in capacitance of a capacitor formed by a single crystal silicon diaphragm that expands and contracts due to pressure fluctuation and an electrode provided on borosilicate glass.

FIG. 6 is a sectional view showing an element in an anode voltage applying step according to a conventional anodic bonding method.

A substrate 21 and a borosilicate glass 11 are sequentially placed on a heater electrode 22, and then an anode voltage is applied by using a needle electrode 23. The bonding spreads around the needle electrode 23.

FIG. 7 is a cross-sectional view showing an element in an anode voltage applying step according to a different conventional anodic bonding method.

[0007] The substrate 21 and the borosilicate glass 11 are sequentially placed on the heater electrode 22, and then an anode voltage is applied using the plate electrode 61. Since the plate-shaped electrode 61 is used, the entire surface is simultaneously bonded in a short time.

FIG. 8 is a sectional view showing an element in an anode voltage applying step according to another conventional anodic bonding method.

A borosilicate glass 11 provided with a substrate 21 and a conductive thin film 12 is sequentially placed on a heater electrode 22, and an anode voltage is applied using a needle electrode 23. Uniform bonding is achieved.

[0010]

However, the conventional anodic bonding method has the following problems.

That is, in the anodic bonding method using the plate-shaped electrode 61, the entire surface is simultaneously bonded in a short time, but air bubbles are partially generated, and a portion where bonding is impossible remains.

In the case where the needle-shaped electrode 23 is used, the case having no conductive thin film requires a long time to complete the bonding of the entire surface because the bonding is spread around the needle-shaped electrode 23 and the insulating property is low. In the case of large borosilicate glass or ceramics, the bonding may not reach the outer periphery. Furthermore, the diffusion amount of alkali ions inside the borosilicate glass differs between the bonding surface below the needle-like electrode and the bonding surface apart from the needle-like electrode, resulting in a difference in bonding strength and stress.

In the case where the needle-shaped electrode 23 is used, the case having the conductive thin film does not generate bubbles as in the case where the plate-shaped electrode is used, but there is a problem that a step of peeling the conductive thin film is required.

The present invention has been made in view of the above points, and has as its object to improve the conductive thin film so that no bubbles are generated, the conductive thin film is not required to be peeled off, and efficient and uniform bonding is achieved. It is to provide a possible anodic bonding method.

[0015]

According to the present invention, an anode voltage is applied to a borosilicate glass provided with a conductive thin film on one principal surface through the conductive thin film to thereby form another borosilicate glass. In the anodic bonding method for bonding the main surface and the substrate,
This is achieved by providing a borosilicate glass with a lattice-like conductive thin film having the same pattern as the cutting margin of the substrate when the substrate is cut into chips.

In the above-mentioned invention, the substrate may be made of a metal having a thermal expansion coefficient equivalent to that of borosilicate glass, instead of the conventionally used single crystal silicon, and the conductive thin film may be made of borosilicate glass via ceramics. It is effective to be provided on the acid glass from the viewpoint of matching the thermal expansion coefficients and ensuring the reliability of bonding.

When an anode voltage is applied to the grid-like conductive thin film,
The electric field distribution of the borosilicate glass becomes almost uniform, and the electric field diffusion of the alkali ions in the borosilicate glass occurs instantaneously in the entire bonding region.

If the pattern of the grid-like conductive thin film is made the same as the cutting margin of the substrate, all the grid-like conductive thin film is removed when the substrate is chipped, and the step of peeling the grid-like conductive thin film becomes unnecessary.

When the conductive thin film is formed in a lattice shape and a voltage is applied from any one point in the lattice shape, the junction is sequentially expanded from one point to facilitate the escape of gas.

[0020]

FIG. 1 shows the steps of an anodic bonding method according to the present invention, wherein (1-a) is a plan view of an element having a conductive thin film formed thereon, and (1-b) is a plan view of a device having a conductive thin film formed thereon. It is sectional drawing of an element.

FIG. 2 shows the steps of the anodic bonding method of the present invention, wherein (2-a) is a plan view of a device having a lattice-like conductive thin film formed thereon, and (2-b) is a lattice-form conductive thin film formed thereon. It is sectional drawing of an element.

A conductive thin film is formed on one surface of borosilicate glass such as Pyrex glass by a method such as sputtering to a thickness of several hundreds to several thousand Å, and a film having a width of several tens to several hundreds μm is formed by a method such as photolithography. A lattice-shaped conductive thin film pattern is obtained.

FIG. 3 is a sectional view showing an element in an anode voltage applying step in the anodic bonding method of the present invention.

A metal such as a single crystal silicon substrate or an Fe—Co—Ni alloy having a coefficient of thermal expansion similar to borosilicate glass is placed on the heater electrode 22.
The borosilicate glass 11 on which is formed is placed, and the needle-like electrode 23 is brought into contact with the grid-like conductive thin film 13. The substrate 21 is heated to 300 to 700 ° C. through a heater electrode, and
Is applied to the needle electrode 23 for several seconds to several tens of seconds.
After joining, the wafer is cut along the grid-like conductive thin film 13 to form a chip. The grid width of the grid-like conductive thin film is set to be equal to or less than the cutting margin.

FIG. 4 shows the steps of a different anodic bonding method according to the present invention. (4-a) is a plan view of an element having a lattice-like conductive thin film formed thereon, and (4-b) is a lattice-form conductive thin film formation. FIG. 4C is a cross-sectional view of the element, and FIG.

A conductive thin film is formed on one surface of the ceramic by sputtering or the like to a thickness of several hundreds to several thousand Å,
A pattern of a grid-like conductive thin film having a width of several tens to several hundreds μm is obtained by a method such as photolithography. On the other surface of the ceramic, a borosilicate glass thin film 32 is formed.

FIG. 5 is a sectional view showing an element in an anode voltage applying step according to a different anodic bonding method of the present invention.

A metal such as a single-crystal silicon substrate or a Fe-Co-Ni alloy having a coefficient of thermal expansion similar to borosilicate glass is placed on the heater electrode 22, and a grid-like conductive thin film 13 is formed on one surface. A ceramic 31 having a borosilicate glass thin film 32 formed on the other surface is placed thereon to form a lattice-shaped conductive thin film 13.
To the needle electrode 23. The substrate 21 is heated to 300 to 700 ° C. through the heater electrode, and an anode voltage of 200 to 1000 V is applied to the needle electrode 23 for several seconds to several tens of seconds. After joining, the wafer is cut along the grid-like conductive thin film 13 to form a chip. The grid width of the grid-like conductive thin film is set to be equal to or less than the cutting margin.

[0029]

According to the present invention, an anode for applying an anode voltage to a borosilicate glass having a conductive thin film provided on one main surface via a conductive thin film to join the other main surface of the borosilicate glass to a substrate. In the bonding method, the borosilicate glass is provided with a lattice-like conductive thin film having the same pattern as the cutting margin of the substrate when the substrate is cut into chips, so that the borosilicate glass is formed by the anode voltage applied to the lattice-like conductive thin film. And the electric field is uniformly distributed, and the electric field diffusion of the alkali ions in the borosilicate glass instantaneously occurs in the entire bonding region, so that efficient anodic bonding can be performed efficiently. Also, by making the pattern of the grid-like conductive thin film the same as the cutting margin of the substrate,
When the substrate is formed into chips, all of the grid-like conductive thin film is removed, and a step of removing the grid-like conductive thin film becomes unnecessary. Further, since the conductive thin film has a lattice shape, a place where no conductive thin film exists is generated, so that gas escapes easily and bubbles are not generated.

[Brief description of the drawings]

FIG. 1 shows the steps of the anodic bonding method of the present invention,
a) is a plan view of an element on which a conductive thin film is formed, and (1-b)
Is a cross-sectional view of an element with a conductive thin film

FIG. 2 shows the steps of the anodic bonding method of the present invention,
a) is a plan view of an element on which a grid-like conductive thin film is formed, (2)
-b) is a cross-sectional view of a device on which a grid-like conductive thin film is formed.

FIG. 3 is a cross-sectional view showing an element in an anode voltage applying step according to the anodic bonding method of the present invention.

FIG. 4 shows the steps of a different anodic bonding method according to the invention,
(4-a) is a plan view of an element having a lattice-like conductive thin film formed thereon, (4-b) is a cross-sectional view of an element having a lattice-like conductive thin film formed thereon, and (4-c) is a sectional view of the element having a lattice-like conductive thin film. Back view of formed device

FIG. 5 is a sectional view showing an element in an anode voltage applying step according to a different anodic bonding method of the present invention.

FIG. 6 is a cross-sectional view showing an element in an anode voltage applying step according to a conventional anodic bonding method.

FIG. 7 is a cross-sectional view showing an element in an anode voltage applying step according to different conventional anodic bonding methods.

FIG. 8 is a cross-sectional view showing an element in an anode voltage applying step according to another conventional anodic bonding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Borosilicate glass 12 Conductive thin film 13 Lattice conductive thin film 21 Substrate 22 Heater electrode 23 Needle electrode 31 Ceramics 32 Borosilicate glass thin film 61 Plate electrode

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Koji Matsushita 1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in Fuji Electric Co., Ltd. (Reference) 2F055 AA40 BB20 CC02 DD01 DD05 DD07 DD09 EE25 FF43 GG01 GG12 4M112 AA01 BA07 CA15 DA18 DA20 EA13

Claims (3)

[Claims] An anodic bonding method for applying an anodic voltage to a borosilicate glass having a conductive thin film provided on one main surface via a conductive thin film to bond the other main surface of the borosilicate glass to the substrate. An anodic bonding method comprising: providing a borosilicate glass with a grid-like conductive thin film having the same pattern as a cutting margin of a substrate when cutting into chips. 2. The anodic bonding method according to claim 1, wherein the substrate is a metal having a thermal expansion coefficient equivalent to that of borosilicate glass. 3. The anodic bonding method according to claim 1, wherein the conductive thin film is provided on the borosilicate glass via a ceramic.