Electroplating apparatus

Details Electroplating apparatus Electroplating apparatus

2002-03-06

2004-09-28

Valentine, Donald R. (Department: 1742)

Chemistry: electrical and wave energy

Apparatus

Electrolytic

C204S222000, C204S273000

Reexamination Certificate

active

06797135

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of forming an electrically-conductive layer having excellent adhesiveness and uniformity, and an electroplating apparatus.
2. Background of the Related Art
The related art suggests several methods of forming metal-conductive oxide layers. For example, plasma vapor deposition, laser-induced reflow, chemical vapor deposition, electroless deposition and electroplating can create oxidation-proof, wear-proof decoration and wires in semiconductor devices. Of those methods, electroplating and electroless deposition provide high-quality conductive layers possessing excellent deposition characteristics at low process temperatures and low equipment costs.
Electroplating requires the formation of a thick, continuous seed layer on a surface of a plated body. Because the seed layer generates a conductive layer, a low resistance contact must form against the seed layer. For example, a chromium seed layer must be deposited on the stainless steel layer of a plated body in order to electroplate that stainless steel layer with nickel.
To form the seed layer, the solid surface is etched to remove impurities. Next, the plated body is placed in a plating bath containing electrolytes inside a process chamber to prevent formation of natural oxide. As shown in
FIG. 1
, a metallic seed layer
11
is formed on the surface of a plated body
10
by chemical vapor deposition (CVD) or sputtering, a physical vapor deposition (PVD) method. That seed layer
11
is oxidation-proof and contamination-resistant, and consists of the same or a different substance from the material used for the plated body
10
.
Once the seed layer
11
forms, a plating bath is used to continue the electroplating process. That process involves a power supply, an electrolytic solution, a solid metal and a plated body
10
. A positive terminal of the power supply connects to the solid metal, while a negative terminal of the power supply connects to the plated body
10
. Once those terminal connections have been completed, the solid metal and the plated body
10
are dipped in the electrolyte solution, which contains an ionic species of the solid metal, to initiate the electroplating process.
When the power supply is transited to the ‘ON’ position, the ionic metal species in the electrolytic solution migrate to the negatively-charged plated body
10
, and are deposited on that body to produce a plating layer
12
above the seed layer
11
. That deposition process continues until a layer of desired thickness forms. The concentration of cations in the electrolyte solution is maintained as the metal dissolves in the electrolyte solution to compensate for the cations lost in the plating process.
A conductive metal or metal alloy layer as the plating layer
12
results from the electroplating process. The physical or chemical surface treatment of a surface of the plated body
10
before starting the electroplating process removes natural oxides, defects, organic/inorganic foreign contaminants, and impurities on the metal surface of the plated body, so as to form a desired uniform plating layer with strong adhesiveness to the plated body.
That surface treatment is necessary because contaminants and impurities interfere with the nucleation of plating material at the pristine stage. The contaminants and impurities deteriorate the uniformity of the conductive layer and its adhesiveness to the plated body
10
. The adhesion between the plated body
10
and the conductive layer
12
is reduced because the space between the deposited metal grains increases because of the poor seed distribution on the plated body
10
. As a result, the characteristics and quality of the plating layer
12
deteriorate. In contrast, less space between the grains corresponds with increased adhesion between the plated body
10
and the plating layer
12
and results in a higher quality metal layer with greater conductivity.
FIG. 4
shows a schematic drawing of a scanning electron microscope (SEM) image of a surface of an electroplating layer
12
formed by a related art. A plurality of metal grains
40
,
41
grows to form the electroplated layer shown on a seed layer
42
. Most of the grains
40
,
41
are small in size, and the grain density per unit area is too low to form a highly adhesive, uniform surface. The grains
40
,
41
continue to grow to fill in the spaces between the grains and form the plating layer as the whole grains connect to one another. Since the interfaces between the plating layer and the seed layer fail to provide sufficiently dense spaces among the grains, vacant spaces develop under the interfaces. The resulting deterioration of the adhesiveness between the seed layer and the plating layer is disadvantageous to forming a uniform layer.
However, as described above the related art has various disadvantages. The electroplating process of the related art is complicated because a surface of a plated body requires an additional process to conduct chemical surface treatment or to form a seed layer. To form a uniform plating layer, the seed layer requires an expensive metal that is difficult to contaminate. Additional complexities result from the poor adhesiveness between the plated body and the seed layer, as the grains are non-uniform and sparsely formed.
The above description and other related art of the electroplating process are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method of forming a conductive layer and an electroplating device thereof that substantially obviates one or more limitations and disadvantages of the related art.
An object of the present invention is to provide a method of forming a conductive layer, and an electroplating device using same that provides a uniform conductive layer on a plated body.
Another object of the present invention is to provide a method of forming a conductive layer and an electroplating device using same that provides a conductive layer with excellent adhesion to a plated body.
Another object of the present invention is to provide a method of forming a conductive layer and an electroplating device using the same that uses supersonic waves.
Another object of the present invention is to provide a method of forming a conductive layer and an electroplating apparatus thereof that provides a uniform conductive layer with excellent adhesion to a plated body by adding a supersonic generator to an electroplating unit.
To achieve at least these and other objects and advantages in whole or in parts and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention includes the steps of placing a sonic wave generator in an electrolyte solution, dipping a plated body connected to a negative terminal of a power supply with a switch and a plating body connected to a positive terminal of the power supply in the electrolyte solution where the power supply includes a switch, generating super sonic waves by operating the sonic wave generator, turning on the power supply by operating the switch, turning off the power supply by operating the switch after a predetermined time, and taking the plated body out of the electrolyte solution.
In a further aspect, the present invention includes a first bath filled with a liquid, a second bath filled with an electrolyte solution wherein the second bath is placed in the first bath, a sonic wave generator capable of propagating super sonic waves to the electrolyte solution, a power supply having a first and second terminals and a switch, a plated body connected electrically to the first terminal of the power supply, and a plating body connected electrically to the second terminal of the power supply where the plating body includes a substance that provides ions of the same species dissolved in the electrolyte solution.
In a further aspect, the present inv

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