Ultrapure hydroxylamine compound solutions and process of making same

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 containing a hydroxylamine solution. In another embodiment, the present invention relates to an ultrapure solution simply containing hydroxylamine, at least one stabilizer, and water.

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.degree. C. and below about 100 torr thereby
 providing a first distillate; and subjecting the first distillate to
 flashover distillation below about 80.degree. 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.

The following specific examples illustrate the preparation of the purified
 hydroxylamine compound solutions according to the present invention.
 Unless otherwise indicated in the examples and elsewhere in the
 specification and claims, all parts and percentages are by weight, and
 temperatures are in degrees centigrade.
 EXAMPLE 1
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 750 ml of a 15.4% aqueous hydroxylamine solution containing less
 than 1% quercetin is charged to a 1 l flask equipped with a thermometer.
 The flask is connected to two unsilvered glass columns (each
 12".times.3/4") packed with Teflon mesh. The aqueous hydroxylamine
 solution is refluxed for 15 minutes, then collected. During fractional
 distillation, the temperature of the hydroxylamine solution is 49.degree.
 C. under a pressure of 27.5 torr. 455 ml of liquid is collected from the
 receiving flask and 315 ml of a 34.1% hydroxylamine solution is collected
 from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 2 is employed.
 100 ml of a 34.1% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser and an unsilvered 100 ml collecting flask positioned partially
 in an ice bath. During flashover distillation, the temperature of the
 hydroxylamine solution is 65.degree. C. under a pressure of 39 torr. 51 ml
 of a 51% hydroxylamine solution is collected. The hydroxylamine solution
 collected contains no detectable ammonia (less than 0.0001%), no
 detectable quercetin and 5 ppb sodium. Stabilizer can be added to the
 collected hydroxylamine solution.
 EXAMPLE 2
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 800 ml of a 12.3% aqueous hydroxylamine solution containing 2%
 hydroxylammonium sulfate is charged to a 1 l flask equipped with a
 thermometer. The flask is connected to two unsilvered glass columns (each
 12".times.3/4") packed with Teflon mesh. The aqueous hydroxylamine
 solution is refluxed for 15 minutes, then collected. During fractional
 distillation, the temperature of the hydroxylamine solution is 48.degree.
 C. under a pressure of 27.7 torr. 385 ml of liquid is collected from the
 receiving flask and 415 ml of a 24.1% hydroxylamine solution is collected
 from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 2 is employed.
 100 ml of a 24.1% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser and an unsilvered 100 ml collecting flask positioned partially
 in an ice bath. During flashover distillation, the temperature of the
 hydroxylamine solution is 60.degree. C. under a pressure of 33 torr. 48 ml
 of a 44% hydroxylamine solution is collected. The hydroxylamine solution
 collected contains no detectable ammonia, no detectable hydroxylammonium
 sulfate and 3 ppb sodium.
 EXAMPLE 3
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 750 ml of a 9.1% aqueous hydroxylamine solution is charged to a
 1 l flask equipped with a thermometer. The flask is connected to two
 unsilvered glass columns (each 12".times.3/4") packed with Teflon mesh.
 The aqueous hydroxylamine solution is refluxed for 15 minutes, then
 collected. During fractional distillation, the temperature of the
 hydroxylamine solution is 65.degree. C. under a pressure of 25.2 torr. 390
 ml of liquid is collected from the receiving flask and 340 ml of a 16.7%
 hydroxylamine solution is collected from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 2 is employed.
 100 ml of a 16.7% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser and an unsilvered 100 ml collecting flask positioned partially
 in an ice bath. During flashover distillation, the temperature of the
 hydroxylamine solution is 62.degree. C. under a pressure of 29 torr. 42 ml
 of a 35% hydroxylamine solution is collected. The hydroxylamine solution
 collected contains no detectable ammonia and 7 ppb sodium.
 EXAMPLE 4
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 350 ml of a 30.6% aqueous hydroxylamine solution containing
 1.75% hydroxylammonium nitrate is charged to a 1 l flask equipped with a
 thermometer. The flask is connected to two unsilvered glass columns (each
 12".times.3/4") packed with Teflon mesh. The aqueous hydroxylamine
 solution is refluxed for 15 minutes, then collected. During fractional
 distillation, the temperature of the hydroxylamine solution is 58.degree.
 C. under a pressure of 27.5 torr. 130 ml of liquid is collected from the
 receiving flask and 215 ml of a 49.8% hydroxylamine solution is collected
 from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 2 is employed.
 100 ml of a 49.8% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser and an unsilvered 100 ml collecting flask positioned partially
 in an ice bath. During flashover distillation, the temperature of the
 hydroxylamine solution is 68.degree. C. under a pressure of 43 torr. 54 ml
 of a 64% hydroxylamine solution is collected. The hydroxylamine solution
 collected contains no detectable ammonia, no detectable hydroxylammonium
 nitrate and less than 1 ppb sodium.
 EXAMPLE 5
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 700 ml of a 28.7% aqueous hydroxylamine solution is charged to a
 1 l flask equipped with a thermometer. The flask is connected to two
 unsilvered glass columns (each 12".times.3/4") packed with Kynar mesh. The
 aqueous hydroxylamine solution is refluxed for 10 minutes, then collected.
 During fractional distillation, the temperature of the hydroxylamine
 solution is 63.degree. C. under a pressure of 19 torr. 385 ml of liquid is
 collected from the receiving flask and 315 ml of a 41.8% hydroxylamine
 solution is collected from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 3 is employed.
 100 ml of a 41.8% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser, a first unsilvered 100 ml collecting flask positioned partially
 in an ice bath and a second unsilvered 100 ml collecting flask positioned
 partially in an ice bath. During flashover distillation, the temperature
 of the hydroxylamine solution is 70.degree. C. under a pressure of 45
 torr. 45 ml of a 37.8% hydroxylamine solution is collected in the first
 receiver and 13 ml of a 11.8% hydroxylamine solution is collected in the
 second receiver. The hydroxylamine solution collected contains no
 detectable ammonia, 1 ppb potassium and 1 ppb sodium.
 EXAMPLE 6
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 675 ml of a 39.8% aqueous hydroxylamine solution containing 1.4%
 hydroxylammonium nitrate and 0.01% 8-hydroxyquinoline is charged to a 1 l
 flask equipped with a thermometer. The flask is connected to three
 unsilvered glass columns (each 12".times.3/4") packed with Kynar mesh. The
 aqueous hydroxylamine solution is refluxed for 5 minutes, then collected.
 During fractional distillation, the temperature of the hydroxylamine
 solution is 64.degree. C. under a pressure of 46 torr. 370 ml of liquid is
 collected from the receiving flask and 305 ml of a 52.3% hydroxylamine
 solution is collected from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 3 is employed.
 100 ml of a 52.3% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser, a first unsilvered 100 ml collecting flask positioned partially
 in an ice bath and a second unsilvered 100 ml collecting flask positioned
 partially in an ice bath. During flashover distillation, the temperature
 of the hydroxylamine solution is 69.degree. C. under a pressure of 45
 torr. 53 ml of a 61.4% hydroxylamine solution is collected in the first
 receiver and 11 ml of a 27.2% hydroxylamine solution is collected in the
 second receiver. The hydroxylamine solution collected contains no
 detectable ammonia, no detectable hydroxylammonium nitrate, no detectable
 8-hydroxyquinoline, 1 ppb potassium and 1 ppb sodium. Stabilizer can be
 added to the collected hydroxylamine solution.
 EXAMPLE 7
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 725 ml of a 41% aqueous hydroxylamine solution is charged to a 1
 l flask equipped with a thermometer. The flask is connected to one
 unsilvered glass column (12".times.3/4") packed with unsilvered glass
 beads. The aqueous hydroxylamine solution is refluxed for 10 minutes, then
 collected. During fractional distillation, the temperature of the
 hydroxylamine solution is 59.degree. C. under a pressure of 41 torr. 415
 ml of liquid is collected from the receiving flask and 310 ml of a 52.3%
 hydroxylamine solution is collected from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 3 is employed.
 100 ml of a 52.3% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser, a first unsilvered 100 ml collecting flask positioned partially
 in an ice bath and a second unsilvered 100 ml collecting flask positioned
 partially in an ice bath. During flashover distillation, the temperature
 of the hydroxylamine solution is 73.degree. C. under a pressure of 25
 torr. 50 ml of a 68.7% hydroxylamine solution is collected in the first
 receiver and 19 ml of a 48.5% hydroxylamine solution is collected in the
 second receiver. The hydroxylamine solution collected contains no
 detectable ammonia, 1 ppb potassium and 1 ppb sodium.
 EXAMPLE 8
 A fractional distillation apparatus generally similar to FIG. 1 is
 employed. 730 ml of a 15.9% aqueous hydroxylamine solution containing
 1.66% hydroxylammonium sulfate and less than 1% 8-hydroxyquinoline is
 charged to a 1 l flask equipped with a thermometer. The flask is connected
 to two unsilvered glass columns (each 12".times.3/4") packed with Teflon
 mesh. The aqueous hydroxylamine solution is refluxed for 15 minutes, then
 collected. During fractional distillation, the temperature of the
 hydroxylamine solution is 48.degree. C. under a pressure of 27.4 torr. 435
 ml of liquid is collected from the receiving flask and 300 ml of a 34.5%
 hydroxylamine solution is collected from the 1 l flask.
 A flashover distillation apparatus generally similar to FIG. 2 is employed.
 100 ml of a 34.5% hydroxylamine solution is charged to a 250 ml flask
 equipped with a thermometer. The flask is connected to an unsilvered
 condenser and an unsilvered 100 ml collecting flask positioned partially
 in an ice bath. During flashover distillation, the temperature of the
 hydroxylamine solution is 66.degree. C. under a pressure of 40 torr. 52 ml
 of a 52% hydroxylamine solution is collected. The hydroxylamine solution
 collected contains no detectable 8-hydroxyquinoline, no detectable
 hydroxylammonium sulfate, no detectable ammonia and no detectable metals.
 Stabilizer can be added to the collected hydroxylamine solution.
 While the invention has been explained in relation to its preferred
 embodiments, it is to be understood that various modifications thereof
 will become apparent to those skilled in the art upon reading the
 specification. Therefore, it is to be understood that the invention
 disclosed herein is intended to cover such modifications as fall within
 the scope of the appended claims.