On-site generation of ultra-high-purity buffered-HF for semiconductor processing

An on-site subsystem, in a semiconductor device fabrication facility, for providing ultra-high-purity buffered ammonium fluoride or hydrofluoric acid to a semiconductor manufacturing operation, comprising:

• a first evaporation source connected to receive an HF source and to provide a flow of HF vapor therefrom;
• a second evaporation source connected to receive a liquid source of ammonia and to provide a flow of ammonia vapor therefrom;
• said flow of HF vapor being connected to pass through a first ionic purifier unit which provides a recirculating volume of high-purity water, containing a high concentration of HF, in contact with said flow of HF vapor, wherein said first purifier passes purified HF gas;
• and
• said flow of ammonia vapor being connected to pass through a second ionic purifier unit which provides a recirculating volume of high-purity water, containing a high concentration of ammonium hydroxide, in contact with said flow of ammonia vapor, wherein said second purifier passes purified ammonia gas;
• a first generator unit, connected to receive said flow of HF gas from said first purifier and to combine said HF gas with high-purity acidic deionized water to produce ultra-pure hydrofluoric acid, said first generator unit also passing a top stream of impure HF gas contaminated with light impurities;
• said ultra-pure hydrofluoric acid and said flow of ammonia vapor being connected to pass into a second generator, which combines said ammonia vapor into said ultra-pure hydrofluoric acid to produce an aqueous solution of ultra-pure buffered hydrofluoric acid of controlled concentration;
• and
• a piping connection which routes said aqueous solution to points of use in the semiconductor device fabrication facility.