PURIFICATION AND RECOVERY OF TETRAALKYLAMMONIUM HYDROXIDE FROM WASTE DEVELOPER LIQUOR

摘要

PROBLEM TO BE SOLVED: To industrially advantageously purify and recover a high-purity tetraalkylammonium hydroxide reusable in the photolithography process from a waste liquor containing a tetraalkylammonium hydroxide used as a positive- type resist developer. SOLUTION: A waste liquor containing a tetraalkylammonium hydroxide is concentrated and then cooled to crystallize the tetraalkylammonium hydroxide which is then recovered in the form of crystal. Alternatively, the waste liquor is neutralized to remove the resultant insolubilized deposits, and then subjected to electrodialysis in an electrolytic bath using a cation exchange membrane; the resultant electrolyte is then concentrated and cooled to crystallize the aimed tetraalkylammonium hydroxide which is then recovered in the form of crystal.