Analysis of copper ion and complexing agent in copper plating baths
US8118988B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 31, 2008 |
| Grant date | Feb 21, 2012 |
| Priority date | — |
| Expiry date | Dec 23, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N31/164
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A simple titration method involving a single copper ion titrant detected by a copper ion specific electrode provides the concentrations of both copper ions and bath complexing agent (ethylene diamine, for example) in alkaline copper electroplating baths of the type used to deposit or thicken copper seed layers on silicon wafers. Standard addition of an excess of a strong complexing agent (EDTA, for example) and back-titration with the copper ion titrant yields the bath copper ion concentration, and continued titration to a second endpoint, preferably after addition of hydroxide to adjust the pH of the analysis solution, yields the total concentration of bath complexing agent. Based on these analyzes, the concentration of free bath complexing agent may be calculated. The method also provides direct determination of the free bath complexing agent concentration via standard addition of excess bath complexing agent to a sample of the plating bath and titration with the copper ion titrant.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.