Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Utilizing brush or absorbent applicator
Reexamination Certificate
2000-02-09
2002-04-23
Wong, Edna (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Utilizing brush or absorbent applicator
C205S118000
Reexamination Certificate
active
06375823
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-033234, filed Feb. 10, 1999, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to an electroplating technique and, more particularly, to a plating method and plating apparatus for a semiconductor device.
In recent years, copper has received a great deal of attention as an interconnection material in order to reduce the interconnection resistance of an LSI and improve its reliability. The copper interconnection forming methods include CVD, sputter reflow, and plating. Of these methods, plating is simple in process and low in cost, exhibits high filling performance, and can form a high-performance interconnection.
However, currently available plating apparatuses do not satisfactorily consider a semiconductor device manufacturing process. The conventional apparatus basically adopts a “plating bath” method following the plating industry. According to this method, a semiconductor substrate is plated by dipping it in a plating bath or cup filled with a plating solution.
This classical plating method has not achieved progression particularly considering the semiconductor device manufacturing process. Thus, when the method is applied to the semiconductor device manufacturing process, the following serious problems arise.
(1) It is difficult to perform precise control of an absolute film thickness in nanometers that is much smaller than the film thickness in a general plating industry, and to ensure high uniformity on the substrate surface.
(2) Bubbles and dust greatly influence the semiconductor process to which a very low defect density on a fine pattern is demanded.
(3) A voltage/current from a cathode can only be applied from the periphery of a substrate outside a region where a pattern is formed. If the electrode is brought into contact with the inside of the substrate where the pattern is formed, scratches or dust is generated to decrease the product yield. This is disadvantageous in a situation in which the wafer size in the semiconductor process is increasing year by year. That is, the conductive layer of an electroplating solution must be made thick on the wafer surface. Otherwise, the resistance from the cathode potential supply portion at the periphery of the substrate to the center of the substrate increases, failing to ensure the plating current at the center. However, the thickness of the conductive layer is limited by process constraints.
(4) It is difficult to perform locally plating in accordance with a regular pattern formed on a semiconductor substrate. It is also difficult to perform positive control of the film thickness on the surface of a semiconductor substrate (wafer), for example, to make the periphery thick in accordance with requirements in a post-plating step (e.g., CMP). If the plating solution is not wanted to attach to the lower surface of the substrate in order to prevent contamination of the substrate or the like, a special seal must be used to protect the lower surface.
(5) In forming a film into a three-dimensional pattern, film formation on projections cannot be suppressed. An example of the most typical applications of a plating metal film among semiconductor processes is formation of a metal film for forming a damascene interconnection. In the damascene process, a plating metal is buried in an interconnection groove or hole, and a metal film formed outside the groove or hole is removed by CMP or the like. Considering load reduction in a subsequent CMP step or the like, formation of the plating film on a portion except for the groove or hole must be prevented as much as possible. The above-described requirements and problems unique to the semiconductor process obstruct the use of plating.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a plating method and plating apparatus which can easily perform precise control of the plating film thickness and are hardly influenced by bubbles and dust.
It is another object of the present invention to provide a plating method which realizes preferential formation of a plating film to a groove or hole suitable for the damascene process.
It is still another object of the present invention to provide a plating method and plating apparatus capable of performing local plating.
To achieve the above objects, according to the first aspect of the present invention, there is provided a plating method comprising the steps of
preparing a substrate to be processed which has a base plate and a conductive layer formed on at least part of the base plate,
applying a potential of a cathode to the conductive layer,
causing a first impregnated member containing a plating solution in electrical contact with an anode to face the conductive layer, and
relatively moving at least part of the first impregnated member with respect to the conductive layer in order to form a plating film on at least part of the conductive layer.
The step of relatively moving at least part of the first impregnated member with respect to the conductive layer desirably includes the step of vertically moving the at least part of the first impregnated member with respect to the conductive layer.
The step of vertically moving at least part of the first impregnated member with respect to the conductive layer desirably includes the step of moving the anode in contact with the first impregnated member apart from the conductive layer in accordance with plating of the plating film.
The step of vertically moving at least part of the first impregnated member with respect to the conductive layer may include the step of controlling at least one of a moving speed of relative movement in a vertical direction and an application current in accordance with plating of the plating film.
The step of vertically moving at least part of the first impregnated member with respect to the conductive layer desirably includes the step of forming a plating film while alternately repeating an operation of causing the conductive layer and the first impregnated member to face each other and an operation of dipping the first impregnated member into a plating bath containing the plating solution.
The step of connecting the cathode to the conductive layer desirably includes the step of connecting the cathode to the conductive layer by bringing a second impregnated member which contains an electrolytic solution and is connected to the cathode into facing the conductive layer in a different region from a region where the first impregnated member comes into facing the conductive layer.
The second impregnated member can perform the same relative movement as the first impregnated member.
The plating method desirably further includes the step of measuring a film thickness of the plating film by a film thickness measuring mechanism arranged on the conductive layer in a different region from a region where the first impregnated member comes into facing the conductive layer.
The plating method desirably further includes the step of additionally forming the plating film by bringing the impregnated member into facing the conductive layer in accordance with a measurement result of the film thickness measuring mechanism.
The film thickness measuring mechanism desirably performs the same vertical movement as the first impregnated member.
The step of vertically moving at least part of the first impregnated member with respect to the conductive layer can include the step of bringing at least part of the first impregnated member into contact with the conductive layer.
The step of relatively moving at least part of the first impregnated member with respect to the conductive layer can include the step of horizontally moving at least part of the first impregnated member with respect to the conductive layer.
The step of horizontally moving at least part of the first impregnated member with respect to the conductive layer desirably includes the step of bri
Kaneko Hisashi
Matsuda Tetsuo
Okumura Katsuya
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Wong Edna
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