JP2519635B2 - Anodic bonding method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anodic bonding method used for bonding metal, silicon or the like to the surface of an insulating material such as ceramics or glass.

[0002]

2. Description of the Related Art In the manufacturing process of semiconductor pressure sensors and the like, anodic bonding is performed to bond a silicon wafer to the surface of an insulating material such as glass. This anodic bonding method is a method in which an anode is brought into contact with one surface of an insulating material and a cathode is brought into contact with the opposite surface thereof, and a direct current is applied to join the insulating material and the anode. A metal plate is mainly used on the cathode side, and the anodic bonding is performed while supplying the liquid electrode between the metal plate and the insulating material.

Alkaline salts are used as the liquid electrodes. Conventionally, the alkaline salts are supplied in a solid state, and the cathode material receives the heat from the heater for heating the insulating material to form the alkaline salts. Wait until the melting temperature or higher,
The joining was performed while gradually melting. However, in this case, the melting rate of the alkali salt is easily influenced by the ambient temperature, the alkali salt in the solid state is easily spilled from the surface of the insulating material, and a short-circuit accident is likely to occur. However, there is a problem that heat is taken from the insulating material heated to a predetermined temperature by the heater to melt the alkali salt, and the temperature of the insulating material is temporarily lowered.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and enables anodic bonding to proceed steadily without being affected by the outside temperature, and the alkali from the surface of the insulating material. The present invention has been completed in order to provide an anodic bonding method which does not cause salt spillage or temporary temperature drop of the insulating material.

[0005]

The anodic bonding method of the present invention, which has been made to solve the above-mentioned problems, comprises contacting one side of an insulating material with an anode and contacting the other side with a cathode and a liquid electrode. In the anodic bonding method in which a direct current is applied to bond the insulating material and the anode, in the vicinity of the liquid electrode supply port on the cathode side
A heater different from the heater for heating the insulating material is installed in the
Liquid electrode by melting alkali salt just before joining
It is characterized by being used as .

[0006]

The present invention will be described below in more detail with reference to the illustrated embodiments. In the figure, 1 is an insulating material such as glass or ceramics, and 2 is an anode in contact with one surface of the insulating material 1. In the case of a semiconductor pressure sensor, the insulating material 1 is glass and the anode 2 is a silicon wafer. 3 is insulation material 1
In this embodiment, a porous plate is used as the cathode 3. This porous plate is
Inorganic fibers are required to satisfy the conditions such as not reacting with an alkali salt used as a liquid electrode, having heat resistance at a bonding temperature or more, and being easy to process into a predetermined size. Plates (cloth, whiskers, fibers) are used.

A liquid electrode supply port 4 is formed at the center of the porous plate. A heater 5 for heating the liquid electrode is provided around the liquid electrode supply port 4 and is provided in a solid state.
The alkali salt to be supplied is heated to a molten state and then liquid
It is supplied to the surface of the cathode 3 as a body electrode . Further, the anode 2 and the cathode 3 are connected to the DC power source 8 by the lead wires 6 and 7,
A DC voltage of about 200 to 2000 V is applied. Reference numeral 9 denotes a heater for heating the insulating material, which is provided around the insulating material 1 and heats the insulating material 1 to 300 to 400 ° C. The heater 5 for heating the liquid electrode and the heater 9 for heating the insulating material can be controlled independently.

In joining, first, the insulating material 1 is heated to 300 to 400 ° C. by the heater 9 for heating the insulating material, and when heated to the melting point of the alkali salt or more, the liquid electrode supply port
The alkali salt is heated and melted by the heater 5 for heating the liquid electrode provided around the liquid electrode supply port 4 in a liquid state.
From the cathode 3 to the surface of the porous plate. At the same time, a voltage is applied to the anode 2 and the cathode 3 by the DC power source 8 so that the liquid electrode penetrates the porous plate and the insulating material 1
The anodic bonding starts from the portion that has diffused to the surface of the liquid crystal, and the bonding portion gradually expands toward the outer periphery as the liquid electrode diffuses.

As described above, according to the present invention, the alkali salt is heated by the heater 5 different from the heater 9 for heating the insulating material and is brought into contact therewith.
Since the molten state is supplied to the cathode side immediately before the melting, the melting time of the alkali salt is not affected by the ambient temperature as in the conventional case, and the melting can be performed within a fixed time. Therefore, anodic bonding can be stably performed regardless of the melting time. Further, since the alkali salt is supplied in a molten state, it is easy to control the supply amount, and it is possible to prevent the trouble that the solid state alkali salt spills from the surface of the insulating material 1. Although the cathode 3 is arranged on the upper side of the insulating material 1 in the above embodiment, it does not matter if the cathode 3 is turned upside down.

[0010]

As described in detail above, according to the anodic bonding method of the present invention , insulation is provided around the liquid electrode supply port on the cathode side.
A heater different from the heater for heating the material is provided, and this heater is
Since <br/> used as the liquid electrode by melting the alkali salt just before more junction can be made to the joint at a constant speed regardless of the outside temperature, an alkali salt of a solid state spill from the surface of the insulating material This has the advantages that a short circuit accident due to the above can be prevented, the supply amount of the alkali salt can be easily controlled, and the temperature of the insulating material does not drop. Therefore, the present invention contributes significantly to industrial development as an anodic bonding method that solves the conventional problems.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating an anodic bonding method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulation material 2 Anode 3 Cathode 4 Liquid electrode supply port 5 Heater for heating liquid electrode 9 Heater for heating insulation material

Claims (1)

(57) [Claims] 1. An anodic bonding method in which an anode is brought into contact with one surface of an insulating material and a cathode and a liquid electrode are brought into contact with the opposite surface of the insulating material and a direct current is applied to join the insulating material and the anode . Around the liquid electrode supply port, a heat
A heater separate from the
An anodic bonding method, characterized in that an alkali salt is previously melted and used as a liquid electrode .