Chemistry: electrical and wave energy – Apparatus – Electrolytic
Utility Patent
1998-01-22
2001-01-02
Gorgos, Kathryn (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S230700, C204SDIG007
Utility Patent
active
06168693
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the electroplating metal on substrates, a system for electroplating metal on substrates, and control system for controlling electroplating on substrates and a method of electroplating metal on substrates.
BACKGROUND OF THE INVENTION
In the production of microelectronic devices, metal may be plated on a substrate for a variety of purposes. Typically, metal is plated on the substrates in cells or reservoirs that hold a plating solution that includes at least one metal to be plated on the substrate.
In microelectronic device manufacture, it is often desirable for metal to be uniformly deposited across a substrate. In electrodeposition of metals, uniformity of the deposited metals is typically coupled to thickness of the deposited metal. This is particularly so in electrodeposition of metals on thin seed layers. Simultaneous control of deposited metal thickness and uniformity on various thin seed layers is rather difficult.
Typically, for a given thin seed layer thickness, electroplated metal uniformity improves with increasing metal thickness. For example, in copper deposition, for ULSI interconnection, the uniformity of a deposit of about 500 nm is about 13%. This percentage indicates the percentage of standard deviation in metal thickness with respect to average metal thickness over the surface of the substrate. The uniformity for a deposit of about 1,000 nm is about 9% and about 3% for a deposit of about 2,000 nm. The above illustrates the strong connection between metal uniformity and metal thickness.
Lack of uniformity of deposited metal also presents problems in metal damascene processes. In the damascene process, after metal deposition, the metal overburden is planarized to define the interconnection features or structure.
In such cases, good metal uniformity may actually pose a problem. For example, depending upon the nature of polishing pads, arrangements, choice of slurry, pressure table rotation and other polishing parameters, good metal uniformity may not be desirable. For example a 2&mgr;Cu or Al film with the uniformity of 3% may present a problem for polishing.
During chemical-mechanical polishing (CMP) the edges of wafers may tend to clear before the center of a wafer. Premature exposure of the chips at the wafer edge may cause the chips to be overpolished. As a result, the resistance of metal lines near a wafer edge may tend to be higher than the resistance of those further away from the edge.
SUMMARY OF THE PRESENT INVENTION
An object of the present invention is to provide a method and apparatus for controlling uniformity of at least one metal electroplated on a substrate or workpiece.
Accordingly, the aspects of the present invention provide an electroplating system for plating at least one metal on at least one substrate or workpiece. The system includes at least one plating tank containing a plating solution including at least one metal to be plated on the at least one substrate or cathode. At least one anode is arranged in the at least one plating tank. The at least one anode is at least partially immersed within the plating solution during plating of the at least one metal. A cathode assembly includes at least one thief and at least one workpiece portion. In the cathode assembly, the at least one thief portion is arranged in the vicinity of at least one workpiece to be plated. The at least one thief controls plating of the at least one metal on the at least one portion of the at least one substrate. At least one power supply is connected to the at least one cathode. At least one controller separately controls a flow of power to the at least one workpiece portion of the cathode and the at least one thief portion of the cathode.
The present invention also includes a control system for controlling uniformity of at least one metal electroplated on at least one substrate in the electroplating system. The electroplating system includes at least one plating tank containing a plating solution including the at least one metal to be plated on the at least one substrate. At least one anode is arranged in the at least one plating tank. The at least one anode is at least partially immersed within the plating solution during plating of the at least one metal. The system also includes at least one cathode including at least one workpiece portion in contact with the at least one substrate and at least one thief portion arranged in the vicinity of at least one portion of the at least one substrate for controlling plating of the at least one metal on the at least one portion of the at least one substrate. At least one power supply is connected to the at least one cathode. The control system includes at least one controller for separately controlling a flow of power to the at least one workpiece portion of the cathode and the at least one thief portion of the cathode.
Furthermore, aspects of the present invention include a method of electroplating at least one metal on at least one substrate in an electroplating system including at least one plating tank containing a plating solution including the at least one metal to be plated on the at least one substrate. At least one anode is arranged in the at least one plating tank. The at least one anode is at least partially immersed within the plating solution during plating of the at least one metal. The system also includes at least one cathode including at least one workpiece portion in contact with the at least one substrate and at least one thief portion arranged in the vicinity of at least one portion of the at least one substrate for controlling plating of the at least one metal on the at least one portion of the at least one substrate. At least one power supply is connected to the at least one cathode. At least one controller separately controls a flow of power to the at least one workpiece portion of the cathode and the at least one thief portion of the cathode. The method includes controlling a flow of power to the at least one workpiece portion of the at least one cathode. A flow of power to the at least one thief portion of the at least one cathode is controlled separately from the flow of power to the at least one workpiece portion of the at least one cathode.
Still further aspects of the present invention provide a method of electroplating at least one metal on at least one substrate in an electroplating system. The method includes the step of providing an electroplating system including at least one plating tank containing a plating solution including the at least one metal to be plated on the at least one substrate. At least one anode is arranged in the at least one plating tank. The at least one anode is at least partially immersed within the plating solution during plating of the at least one metal. The system also includes at least one cathode including at least one workpiece portion in contact with the at least one substrate and at least one thief portion arranged in the vicinity of at least one portion of the at least one substrate for controlling plating of the at least one metal on the at least one portion of the at least one substrate. At least one power supply is connected to the at least one cathode. At least one controller separately controls a flow of power to the at least one workpiece portion of the cathode and the at least one thief portion of the cathode. The method also includes utilizing the at least one controller to control a flow of power to the workpiece portion of the cathode. Additionally, the method includes utilizing the at least one controller to control a flow of power to the at least one thief portion of the at least one cathode separately from the flow of power to the at least one workpiece portion of the at least one cathode.
Aspects of the present invention also include a method of electroplating at least one metal on at least one substrate in an electroplating system including at least one plating tank containing a plating solution including the at least one metal to be plated on the at least one substrate. At least one anode is arrange
Landry Gerard Raymond
Uzoh Cyprian Emeka
Gorgos Kathryn
International Business Machines - Corporation
Nicolas Wesley A.
Pollock, Vande Sande & Amernick, R.L.L.P.
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