Distillation: processes – separatory – Plural distillations performed on same material – One a distillation under positive pressure or vacuum
Reexamination Certificate
1998-05-28
2001-05-22
Manoharan, Virginia (Department: 1764)
Distillation: processes, separatory
Plural distillations performed on same material
One a distillation under positive pressure or vacuum
C203S077000, C203S080000, C203S086000, C203S088000, C423S387000
Reexamination Certificate
active
06235162
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to ultrapure hydroxylamine compound solutions and processes for making the ultrapure hydroxylamine compound solutions. In particular, the present invention relates to making ultrapure hydroxylamine compound solutions using fractional distillation and flashover distillation techniques.
BACKGROUND OF THE INVENTION
Hydroxylamine compounds have a variety of useful applications. Generally speaking, hydroxylamine compounds are strong reducing agents. Accordingly, hydroxylamine compounds are useful in stripper formulations. Stripper formulations may be used to remove photoresists from or clean a substrate. For example, hydroxylamine stripper solutions are used to remove developed photoresists, such as patterned polyimide from metal foils. Hydroxylamine stripper solutions are extensively utilized in the printed circuit board fabrication and microelectronic chip fabrication technologies. Hydroxylamine compounds are also useful as intermediaries in chemical processes, especially in the pharmaceutical and agricultural industries.
Frequently, solutions of hydroxylamine, especially solutions prepared from hydroxylammonium salts, contain undesirable amounts of impurities such as salts including hydroxylammonium salts and acid salts, various metals and metal ions, ammonia and unwanted organic materials. Thus, there also exists a need for hydroxylamine solutions having high purity. There exist several production methods to manufacture hydroxylamine compounds.
Some of these methods, however, do not provide hydroxylamine compound solutions of high purity which some applications of the compounds require. While some purification schemes exist, ultra high purity hydroxylamine compound solutions are either difficult to find or expensive to make. Consequently, there remains a substantial demand for large quantities of high purity hydroxylamine compound solutions.
SUMMARY OF THE INVENTION
In one embodiment, the present invention relates to a method of treating a solution containing hydroxylamine, involving subjecting the solution containing hydroxylamine to fractional distillation using a packed column thereby providing a first distillate; and subjecting the first distillate to flashover distillation thereby providing a second distillate comprising a hydroxylamine solution.
In another embodiment, the present invention relates to a method of purifying a solution containing hydroxylamine, involving subjecting the solution containing hydroxylamine to fractional distillation using a packed column below about 75° C. and below about 100 torr thereby providing a first distillate; and subjecting the first distillate to flashover distillation below about 80° C. and below about 100 torr thereby providing a second distillate comprising a purified hydroxylamine solution.
In yet another embodiment, the present invention relates to a method of removing at least a portion of at least one of ammonia and metal contaminants from a solution containing hydroxylamine and at least one of ammonia and metal contaminants, involving subjecting the solution containing hydroxylamine and at least one of ammonia and metal contaminants to fractional distillation using a column packed with a non-metallic material thereby providing a first distillate; and subjecting the first distillate to flashover distillation thereby providing a second distillate containing a hydroxylamine solution containing less of at least one of ammonia and metal contaminants than the solution containing hydroxylamine and at least one of ammonia and metal contaminants.
In still yet another embodiment, the present invention relates to an ultrapure solution simply containing hydroxylamine, at least one stabilizer, and water.
As a result of the present invention, concentrated and ultra-purified solutions of hydroxylamine compounds are obtainable.
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Drew John W.
Sharifian Hossein
Manoharan Virginia
Renner , Otto, Boisselle & Sklar, LLP
Sachem, Inc.
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