Electrolysis and Ion Exchange for the In Process Recycling of Copper from Semi-Conductor Processing SolutionsEPA Grant Number: R829627
Title: Electrolysis and Ion Exchange for the In Process Recycling of Copper from Semi-Conductor Processing Solutions
Investigators: Doyle, Fiona M. , Evans, James W.
Institution: University of California - Berkeley
EPA Project Officer: Carleton, James N
Project Period: January 1, 2002 through December 31, 2004 (Extended to April 30, 2007)
Project Amount: $325,000
RFA: Technology for a Sustainable Environment (2001) RFA Text | Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development
Description:The objectives of the study are to develop an understanding of the electrodeposition of copper onto extended-area electrodes, and of the adsorption/desorption of copper onto ion exchange resins with a high affinity for copper. The principles elucidated in this work will pave the way for subsequent development of commercial-scale electrolysis/ion exchange processes for recovering copper throughout semiconductor fabrication plants.
Four investigations are planned. These are:
(1) Laboratory scale electrochemical investigations using a rotating copper electrode to determine kinetic parameters and the nature of the electrodeposit for the solutions of interest. These tests will identify any side-reactions, and determine mass-transfer parameters that will influence the future design of commercial cells.
(2) Application of various extended surface area electrodes to solutions representative of semiconductor industry wastes. Experimental cells will be built to examine the effects of electrode area, (superficial) current density, electrolyte flowrate and time of electrolysis on cell voltage, current efficiency, ultimate copper concentration and the morphology and purity of the electrodeposited copper.
(3) Measurement of sorption and desorption isotherms for metals on chelating resins and those with a strong affinity for copper. Isotherms will be measured in solutions of different chemistries, and related to the thermodynamic speciation.
(4) Development of a model for uptake and selectivity of metals onto resins, to guide commercial development of effective ion exchange units.
Expected Results:The planned work will yield definitive information on the electrochemical and ion exchange behavior of copper when present in solutions typical of semiconductor industry wastes. These solutions typically contain organic complexing agents, along with other additives such as surfactants, which are likely to influence markedly the behavior of copper and other metals in solution. The work will also reveal the effect of engineering parameters on the performance of electrochemical cells and ion exchange columns.
The electrochemical, ion-exchange behavior and engineering responses will be modeled, to generate a foundation for future design and development of commercial-scale electrolysis/ion exchange processes for recovering copper throughout semiconductor fabrication plants.
These results address the need to develop new technology to minimize the environmental impact of semiconductor manufacture. As the industry moves to copper interconnects, which are generally deposited from solutions, there is an attendant increase in the volume of copper-contaminated spent process solution and rinse water. At present these wastes are generally treated offsite, for detoxification only. This project will explore the scientific and engineering principles that underlie the abstraction of copper from these solutions by a sequence of electrochemistry and ion exchange. This will create a foundation for development of commercial processes that can recycle both copper and water within a semiconductor fabrication plant.
The project aims to eliminate the generation of hazardous, copper contaminated solutions by semiconductor fabrication plants, with concurrent recycling of copper and water. With existing trends, the output of waste water from chemical mechanical planarization alone is expected to increase from 225 million gallons in 1998 to 450 million gallons in 2006. Typical se