Metal fusion bonding – Process – With protecting of work or filler or applying flux
Reexamination Certificate
2001-10-05
2004-05-11
Edmondson, Lynne (Department: 1725)
Metal fusion bonding
Process
With protecting of work or filler or applying flux
C228S206000, C228S019000, C219S388000, C219S390000
Reexamination Certificate
active
06732911
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims priority of Japanese Patent Applications No. 2001-10423, filed in Jan. 18, 2001, and 2001-172960, filed in Jun. 7, 2001, and No. 2001-67615, filed in Mar. 9, 2001, the contents being incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a solder jointing system and a solder jointing method and, more particularly, a solder jointing system and a solder jointing method employed to joint the solder layer to wirings or pads of the semiconductor device or the electronic device.
The present invention relates to a semiconductor device manufacturing method and a semiconductor device manufacturing system and, more particularly, a semiconductor device manufacturing method and a semiconductor device manufacturing system having a step/means for removing unnecessary substance that is adhered onto a surface of the electrode or the wiring formed mainly of copper.
In the prior art, normally the wiring or the electrode of the semiconductor device is made of metal containing mainly aluminum. However, in recent years, in order to satisfy requests for the miniaturization of the wirings and the higher speed, the development of the practical implementation of the wiring that employs the copper having the small resistivity and the high electromigration resistance as main material is being proceeded.
This copper has the property that is reduced more easily than aluminum, but is oxidized easily. Accordingly, in the steps of manufacturing the semiconductor device, the technology of removing quickly and precisely the oxide film formed on the surface of the copper wiring or the copper electrode to clean the surface is requested.
2. Description of the Prior Art
As the method of jointing the solder to the metal pattern such as the electrode pad, the metal wiring, etc. of the semiconductor device, the method of forming the solder on the metal pattern by virtue of the plating method, the printing method, the ball mounting method, etc. and then heating/melting the solder to joint/shape it onto the electrode pad is employed.
In melting the solder, normally the oxide film on the surface of the solder or the electrode pad under the solder is removed by using the flux, and then the solder is melted and jointed while cleaning the surface.
The solder jointing step using the flux is carried out by the method described hereunder, for example.
First, the flux that is coated on the surface of the metal pattern as the solder-deposited surface covers the surface of the metal pattern to prevent the oxidation of the metal pattern while its surface is being activated by the heating, so that the activated state of the metal pattern is maintained. At the same time, the solder is melted to spread over the surface of the metal pattern. A part of the flux is dissolved by the melting of the solder.
Then, the solder is solidified by the cooling and is jointed to the surface of the metal pattern. At the same time, the flux and the dissolved product remaining on the metal pattern are also solidified.
After the solder joint using such flux is executed, the solidified flux is removed by the cleaning. In this case, since the dissolved product cannot be simply removed by the organic solvent not-containing flon or trichlene in this cleaning, a large quantity of organic solvent must be used in this cleaning.
However, since the organic solvent exerts a harmful influence upon the environment, the development of the solder jointing method that does not need the cleaning is desired.
Also, in the packaging step of the electronic parts module, normally the packaging step is applied after the flux or the flux-containing paste is coated on the solder-jointed portion. In such case, since the flux is dissolved by the heat applied in the packaging to thus generate the harmful gas, the safety of the operation must be assured. Also, if the halogen component remains in the module as the residue of the flux, corrosion of the wirings in the module and the migration of the wirings are accelerated. Therefore, the thorough cleaning is needed, which acts as the cause to bring about the increase of the fabrication cost.
In order to overcome these problems, following methods or equipments are known.
First, the soldering method using the carboxylic acid is set forth in Patent Application Publication (KOKAI) Hei 6-190584 (literature 1), Patent Application Publication (KOKAI) Hei 6-267632 (literature 2), and Patent Application Publication (KOKAI) Hei 7-164141(literature 3), for example. Also, the equipment is set forth in literature 3.
Also, the soldering method executed in the low pressure or vacuum atmosphere is set forth in Patent Application Publication (KOKAI) Hei 4-220166 (literature 4), Patent Application Publication (KOKAI) Hei 5-211391 (literature 5), Patent Application Publication (KOKAI) Hei 6-29659 (literature 6), Patent Application Publication (KOKAI) Hei 7-79071 (literature 7), and Patent Application Publication (KOKAI) Hei 7-170063 (literature 8).
However, according to the solder jointing system and the solder jointing method in the prior art, there are subjects described in the following.
First, the first subject is that the danger of the explosion in the solder jointing atmosphere is present.
For example, it is set forth in the literature 3 that, in the solder jointing system using the carboxylic acid and the diketone, the carboxylic acid gas is supplied to reduce the oxide film of the solder and also the droplet of the diketone is supplied to remove the oxide film of the pad. However, the diketone is such material that is expensive as set forth in the literature 3 and has the danger of the explosion. Both the diketone and the carboxylic acid have the explosive limit. If the temperature and the concentration in the processing layer and the oxygen concentration exceed respective certain ranges, e.g., if the formic acid concentration and the oxygen concentration reach 30% and 10% at the temperature of 100° C. respectively, there exists the danger of the explosion.
The equipment and the method that have the possibility to reach such conditions causing the danger of the explosion are not readily accepted.
The second subject is that the carboxylic acid has the poisonous property.
For example, as disclosed in the literature 4, in order to prevent the leakage of the carboxylic acid from the process area, it is advantageous to execute the soldering by introducing the carboxylic acid into the chamber, that is excluded from the air, while reducing the oxide film. However, the solder joint in the chamber has small processing capability.
The third subject is that the re-oxidation is caused by the carboxylic acid that still remains on the surface of the solder and the surface of the metal pattern after the solder joint.
According to the examination of the inventors of the present invention, if the component of the carboxylic acid still remains on the surface of the solder, the surface of the solder is oxidized again after the solder is left as it is for a predetermined time in the atmosphere. Also, if the oxygen concentration of the atmosphere in which the solder joint is carried out is high, the surface of the solder is oxidized again by the residual heat after the heating/melting.
The fourth subject is that the throughput of the solder joint must be improved in the well-known solder jointing system.
The solder is formed on the wiring or the pad of the semiconductor substrate, the ceramic substrate, the circuit board, etc., then is carried into the solder jointing system, and then is heated/melted there to be jointed to the wiring or the pad. Since the substrate is loaded/unloaded one by one into/from the solder jointing system, i.e., such solder jointing system has the so-called sheet-fed processing structure, efficiency of the solder joint is low. For this reason, in order to enhance the substrate processing capability, the solder jointing system in which a plurality of neighboring solder joint areas are provi
Matsui Hiroyuki
Matsuki Hirohisa
Miyajima Motoshu
Mizukoshi Masataka
Mizutani Akiyo
Armstrong Kratz Quintos Hanson & Brooks, LLP
Edmondson Lynne
Fujitsu Limited
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