Point-of-use ammonia purification for electronic component manufacture
AssigneeStartec Ventures, Inc.
InventorsJoe G. Hoffman, R. Scot Clark
Life of this patent
Estimating the term…
Abstract
Highly purified ammonia for use in processes for the production of high-precision electronic components is prepared on-site by drawing ammonia vapor from a liquid ammonia reservoir, passing the vapor through a filter capable of filtering out particles of less than 0.005 micron in size, and scrubbing the filtered vapor in a high-pH aqueous scrubber.
Claims19
A system for the preparation of ultra-high purity ammonia, said system comprising:
- (a) a reservoir of liquid ammonia with a vapor space above said liquid ammonia;
- (b) means for drawing vapor containing ammonia gas from said vapor space;
- (c) a filtration membrane removing particles greater than 0.005 micron from vapor thus drawn;
- and
- (d) an aqueous ammonia scrubber containing an aqueous solution of ammonia in deionized water, arranged to contact filtered vapor having passed through said filtration membrane with said aqueous solution, the vapor thus scrubbed being purified ammonia gas.
A system for the manufacture of a high-precision electronic component, said system comprising:
- (a) a production line containing a plurality of workstations successively arranged for treating a workpiece to be formed into said electronic component, one such workstation selected for application of ammonia to said workpiece;
- (b) means for conveying said workpiece to said workstations in succession along said production line;
- and
- (c) a subunit adjoining said production line at said selected workstation to supply said ammonia in ultra-high purity form, said subunit comprising:
- (i) a reservoir of liquid ammonia with a vapor space above said liquid ammonia;
- (ii) means for drawing vapor containing ammonia gas from said vapor space;
- (iii) a filtration membrane removing particles greater than 0.005 micron from vapor thus drawn;
- and
- (iv) a scrubber arranged to contact filtered vapor having passed through said filtration membrane with an aqueous solution of ammonia in deionized water, the vapor thus scrubbed being purified ammonia gas;
- and
- (d) means for applying the product of step (c) directly to a workpiece at said workstation;
- said production line, said conveying means and said subunit all being free of contamination by semiconductor manufacturing standards defined as a resistivity of at least about 15 megohm-cm at 25.degree. C., less than about 25 ppb of electrolytes, a particulate content of less than about 150/cm.sup.3 and a particle size of less than 0.2 micron, a microorganism content of less than about 10/cm.sup.3, and total organic carbon of less than 100 ppb.
A method for supplying a high-purity ammonia reagent to a workstation in a production line for the manufacture of a high-precision electronic component, said method comprising:
- (a) drawing ammonia gas from a vapor space above liquid ammonia in an ammonia-containing reservoir;
- (b) passing said ammonia gas through a filtration membrane removing particles greater than 0.005 micron therefrom;
- (c) passing said ammonia gas thus filtered through a scrubber wherein said ammonia gas is contacted with an aqueous solution of ammonia in deionized water;
- and
- (d) recovering said ammonia gas emerging from said scrubber and directing said ammonia gas to said workstation.
Dependencies are inferred from the claim text.