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Electrolytic copper plating solutions

Inactive Publication Date: 2006-03-30
BARSTAD LEON R +6
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0016] Electroplating baths of the invention are characterized in significant part by comprising enhanced brightener concentrations. Without being bound by any theory, it is believed that the higher brightener, concentrations can accelerate the plating rate in recesses and microvias as carrier molecules become incorporated into the plating deposit This is counterintuitive to conventional thought and a completely unexpected result.
[0019] In addition to such an elevated brightener concentration, preferably the plating bath also contains a surfactant-type suppressor agent. It has been surprisingly found that use of such a suppressor agent in combination with elevated brightener concentrations can result in effective “bottom-fill” copper plating of a microvia or other aperture without defects such as inclusions or voids. In particular, the suppressor enables enhanced plating rate at the bottom of a microvia, permitting copper to plate the entire aperture space in a substantially “bottom-fill” manner, without premature sealing of the aperture top that can result in inclusions or voids.

Problems solved by technology

Without being bound by any theory, it is believed that the higher brightener, concentrations can accelerate the plating rate in recesses and microvias as carrier molecules become incorporated into the plating deposit This is counterintuitive to conventional thought and a completely unexpected result.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0060] A preferred copper electroplating bath of the invention was prepared by admixing the following components in water. In the composition the brightener was bis-sodium-sulfonopropyl-disulfide and the suppressor was a polyethylene glycol polymer sold under the tradename PEG 8000 by Union Carbide.

ComponentConcentrationCuSO4 5H2O60g / lH2SO4225g / lCl50ppmSuppressor1g / lBrightener2.1mg / l

[0061] Through hole walls of a printed circuit board substrate and microvias were plated as follows with the above plating composition. An air-agitated plating tank outfitted with multiple cathode rails and one rectifier was charged with the above copper plating solution. During plating, the following deposition conditions were employed: current density of 14.5 mA / cm2; waveform was DC; temperature plating bath was 25° C. After termination of the plating procedure, a microvia of the board substrate was examined. It was found that copper completely filled the microvia walls to provide a smooth uniform co...

example 2

[0062] A further preferred copper electroplating bath of the invention was prepared by admixing the following components in water. In the composition the brightener was bis-sodium-sulfonopropyl-disulfide and the suppressor was a propylene glycol copolymer sold under the tradename L62D by BASF.

ComponentConcentrationCuSO4 5H2O70g / lH2SO4175g / lCl50ppmSuppressor0.875g / lBrightener2.4mg / l

[0063] 200 nm with 7:1 aspect ratio microvias of a back end of the line semiconductor microchip wafer were plated using the above plating composition. The wafer was electrically attached to a cathode and the plating solution was pumped onto the surface of the wafer while rotating at upwards of 200 RPM. Electrical current of 14.5 mA / cm2 was applied with DC wave form at 25° C. After termination of the plating procedure, the microvias were filled with no defects as determined by focused ion beam examination.

example 3

COMPARATIVE EXAMPLE

[0064] A further preferred copper electroplating bath of the invention was prepared by admixing the following components in water. In the composition the brightener was bis-sodium-sulfonopropyl-disulfide and the suppressor was a propylene glycol copolymer sold under the tradename L62D by BASF.

ComponentConcentrationCuSO4 5H2O60g / lH2SO4225g / lCl50ppmSuppressor1g / lBrightener0.35mg / l

[0065] 200 nm with 4:1 aspect ratio microvias of a semiconductor microchip wafer were plated using the above comparative plating composition under conditions as described in Example 2. After termination of the plating procedure, the microvias were examined by scanning electron microscopy (SEM) and focused ion beam examination. Those examinations showed the copper deposits in the microvias contained defects of voids, seams and inclusions.

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Abstract

The present invention provides inter alia copper electroplating compositions, methods for use of the compositions and products formed by the compositions. Electroplating compositions of the invention contain an increased brightener concentration that can provide effective copper plate on difficult-to-plate aperture walls, including high aspect ratio, small diameter microvias.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to copper electroplating solutions, methods for using the solutions and products formed by using such methods and solutions. More particularly, the invention provides electrolytic copper plating solutions that have increased brightener levels and use of same for effective plating of high aspect ratio apertures, e.g. microvias with aspect ratios of at least 4:1 and diameters of 200 nm or smaller. [0003] 2. Background [0004] Electroplating articles with copper coatings is generally well known in the industry. Electroplating methods involve passing a current between two electrodes in a plating solution where one electrode is the article to be plated. A common plating solution would be an acid copper plating solution containing (1) a dissolved copper salt (such as copper sulfate), (2) an acidic electrolyte (such as sulfuric acid) in an amount sufficient to impart conductivity to the bath an...

Claims

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Application Information

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IPC IPC(8): C25D5/34C25D3/38C25D5/48C25D7/00C25D7/12H01L21/288H05K3/42
CPCC25D3/38H05K3/423C25D5/48C25D3/00
Inventor BARSTAD, LEON R.RYCHWALSKI, JAMES E.LEFEBVRE, MARKMENARD, STEPHANEMARTIN, JAMES L.SCHETTY, ROBERT A. IIITOBEN, MICHAEL P.
Owner BARSTAD LEON R
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