Process for removing metal ions from organic photoresist solutions

DETAILED DESCRIPTION We claim: 1.
A process for removing metal ions from organic solution containing one or more dissolved acid labile photoresist components without formation of by-products, said process comprising the steps of providing said organic photoresist solution containing said acid labile components, providing a cation exchange resin modified by having strong acid protons displaced with ammonium ions by contact of the cation exchange resin with ammonium hydroxide, and contacting said organic solution with said modified cation exchange resin for a time sufficient to remove essentially all of said metal ions from said solution.
2.
The process of claim 1 where the modified cation exchange resin is dehydrated by contact with an organic solvent prior to contact with said organic solution.
3.
The process of claim 2 where the photoresist solution contains a solvent having acid labile groups.
4.
The process of claim 3 where the solvent is ethyl lactate.
5.
The process of claim 1 where the solution is passed through a column of the cation exchange resin.
6.
The process of claim 1 where the solution is slurried with the cation exchange resin.




Description:
BACKGROUND OF THE INVENTION 1.
Introduction This invention relates to removal of metal ions from organic solvents.
The invention is especially useful for the removal of metal ions from organic solvents and solutions of photoresist components.
2.
Description of the Prior Art It is known in the art that organic solvents are often contaminated with metal ions.
This contamination is typically due to raw materials used to manufacture the solvent, the reactants, and the reaction vessels in which the solvents are prepared.
The level of metal ion contamination in a solvent may range up to about 500 parts per million parts of solvent (ppm) or more dependent upon the solvent and the manner in which the solvent is prepared.
For many commercial applications, this level of metal ion contamination is acceptable.
However, for other commercial applications, such as use of organic solvents in the manufacture of pharmaceuticals, radio pharmaceuticals, processing chemicals such as functionalized silanes for optical fibers, adhesion promoters, acid sensitive hydraulic fluids, dielectric fluids, reference standards and in the manufacture of chemicals for microlithography, this level of contamination is unacceptable