Electroplating bath analysis

Patent metadata

Field	Value
Publication number	US-9612217-B2
Application number	US-201514693818-A
Country	US
Kind code	B2
Filing date	Apr 22, 2015
Priority date	Apr 22, 2014
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

Electrochemical impedance spectroscopy is used to determine the amount of organic additive in a metal electroplating bath.

First claim

What is claimed is:

1. A method for determining the concentration of one or more organic components in a metal electroplating bath comprising the steps of:
a) providing an apparatus having a rotatable working electrode, a counter electrode, a reference electrode, a potentiostat, and a frequency response analyzer, wherein the counter electrode is in operable communication with the working and reference electrodes;
b) obtaining a metal electroplating bath solution comprising an unknown quantity of organic additive;
c) contacting each of the working electrode, reference electrode and counter electrode with the metal electroplating solution, and cleaning the working electrode surface by applying a positive potential while rotating the working electrode at a first rotation speed;
d) equilibrating convection in the electroplating solution by rotating the working electrode at a second rotation speed at open circuit potential, wherein the second rotation speed is different from the first rotation speed;
e) applying a potential to the working electrode that is 50 to 500 mV negative of a metal underpotential deposition peak and overlaying an alternating potential perturbation of from 1 to 100 mV;
f) measuring an impedance response of the organic additive solution over a frequency range of from 10 kHz to 1 mHz;
g) selecting a frequency from the impedance response; and
h) determining a concentration of the organic additive by comparing the impedance response at the selected frequency to a calibration curve.

2. The method of claim 1 wherein the metal is copper.

3. The method of claim 1 wherein the alternating potential perturbation is chosen from a sine wave and a square wave.

4. The method of claim 1 wherein the first rotation speed is faster than the second rotation speed.

5. The method of claim 1 wherein the working electrode is a platinum disc.

6. The method of claim 1 wherein the counter electrode comprises platinum.

7. The method of claim 1 wherein the organic additive is chosen from accelerators, suppressors, levelers, and mixtures thereof.

8. The method of claim 1 wherein the impedance is selected at a frequency of 1 Hz.

9. The method of claim 1 wherein a plurality of frequencies is selected in step g).

Assignees

• Rohm & Haas Elect Mat
• Rohm And Haas Electronics Mat Llc

Inventors

• Thorseth Matthew A

Classifications

• C25D3/38

  of copper · CPC title

• G01N27/026 Primary

  Dielectric impedance spectroscopy (electrochemical impedance spectroscopy for measuring corrosion G01N17/02) · CPC title

• C25D21/14

  Controlled addition of electrolyte components · CPC title