EP1193309A1

EP1193309A1 - Solvent blend for use in high purity precursor removal

Info

Publication number: EP1193309A1
Application number: EP01122661A
Authority: EP
Inventors: Robert Sam Zorich; Xinjian Lei; David James Silva; Cynthia Lee Trent
Original assignee: Air Products and Chemicals Inc
Current assignee: Air Products and Chemicals Inc
Priority date: 2000-09-29
Filing date: 2001-09-28
Publication date: 2002-04-03
Anticipated expiration: 2021-09-28
Also published as: DE60106838D1; EP1193309B1; TW486392B; JP2002219432A; DE60106838T2; KR100408736B1; KR20020025820A; ATE281510T1

Abstract

The present invention is a process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of the high purity source chemical through the manifold is discontinued, comprising; evacuating the manifold by connection to a source of vacuum, terminating the evacuation, introducing at least one solvent for the high purity source chemical into the manifold from at least one source of the at least one solvent, dissolving any residual high purity source chemical in the manifold into the at least one solvent, venting a resulting mixture of residual high purity source chemical and solvent from the manifold, purging such as by pressurizing the manifold by connection to a source of preferably elevated pressure inert gas and terminating the purging i.e. pressurizing, before reintroducing high purity source chemical into the manifold.

Description

BACKGROUND OF THE INVENTION

The Present Invention is directed to the field of process chemical delivery in the electronics industry and other applications requiring high purity chemical delivery. More specifically, the present invention is directed to solvent blends and processes for the cleaning of process chemical delivery lines, containers and associated apparatus, particularly during changeout of process chemical or process chemical containers in such process chemical delivery lines.
Evacuation and gas purge of process chemical lines has been used to remove residual chemicals from delivery lines. Both vacuum draw and inert gas purge are successful in quickly removing high volatility chemicals, but are not effective with low volatility chemicals. Safety is a problem when extracting highly toxic materials.
Use of solvents to remove residual chemicals is not new. Various patents have sought to clean systems using solvents, which are hereby specifically incorporated by reference in their entirety herein:
US 5,045,117 describes a method and apparatus for cleaning printed wiring assemblies with a solvent and vacuum action.
US5,115,576 discloses an apparatus and method of cleaning semiconductor wafers using isopropyl alcohol solvent.
Additional patents regarding solvent cleaning include; US 5,744,436; US 5,605,647; US 5,494,601; US 5,560,861; US 4,578,209; US 5,135,676; US 5,607,912; US 5,762,817; US 5,352,375; US 5,827,454; US 5,275,669; US 5,750,488; US 5,444,102; US 6,042,749; US 5,531,916; US 5,118,359; US 5,298,083; US 5,304,322. US 5,562,861; US 5,685,915; US 5,695,688; US 5,716,549; EP 710715A1; JP 7316595A2; JP 8034996A2; JP 8120298A2.
The present invention overcomes the deficiencies in the prior art of cleaning process lines or piping by the novel use of a solvent blend, in particular, a perfluorohexane/heptane blend, that provides for maximum cleaning efficiency, and minimal environmental impact for use in cleaning the interior ultrahigh purity piping walls of a chemical delivery system. In this case, the high purity precursor resides in a delivery line, requiring removal. In certain cases, the volatility of the precursor is too low to be removed using classical vacuum purge techniques. The parameters of the present invention and the benefits that flow from it to ovecome the deficiencies in the prior art are set forth in greater detail below.

BRIEF SUMMARY OF THE INVENTION

The present invention is a process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of the high purity source chemical through the manifold is discontinued, comprising; evacuating the manifold by connection to a source of vacuum, terminating the evacuation, introducing at least one solvent for the high purity source chemical into the manifold from at least one source of the at least one solvent, dissolving any residual high purity source chemical in the manifold into the at least one solvent and venting a resulting mixture of residual high purity source chemical and solvent from the manifold. Preferably, after venting the solvent, the process is proceeds by purging the manifold by connection to a source of inert gas and then terminating the purging.
Alternatively, the present invention can avoid the prior evacuation and purging or pressurization, and merely drain the residual chemical from the manifold before solvent purging. In that instance, the invention is a process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of the high purity source.chemical through the manifold is discontinued, comprising; draining the manifold by connection to a vent, introducing at least one solvent for the high purity source chemical into the manifold from at least one source of the at least one solvent, dissolving any residual high purity source chemical in the manifold into the at least one solvent and venting a resulting mixture of residual high purity source chemical and solvent from the manifold.
Preferably, the at least one solvent is a blend of a fluorocarbon containing solvent and a hydrocarbon solvent. More preferably, the at least one solvent is a blend of solvents and one solvent renders the high purity source chemical nonflammable. Optimally, the at least one solvent is a blend of solvents and one solvent renders the high purity source chemical nonhazardous.
The high purity chemical is selected from the group consisting of tantalum pentaethoxide (TAETO), tetrakis(diethylamino) titanium (TDEAT), tetrakis(dimethylamino) titanium (TDMAT), tetramethylcyclotetrasiloxane (TMCTS), copper hexafluoroacetylacetonate- trimethylvinylsilane (Cu(hfac)TMVS), tetraethylorthosilicate (TEOS), trimethylborate (TMB), triethylborate (TEB), trimethylphosphite (TMPi), triethylphosphate (TEPO), bistertiarybutylaminosilane (BTBAS), tantalumtetraethoxidedimethylaminoethoxide (TAT-DMAE), t-butylimidotrisdiethylamido tantalum (TBTDET), triethyl arsenite (TEOA), polyarylene ethers and mixtures thereof.
The at least one solvent is selected from the group consisting of organic alcohols such as methanol, ethanol, propanol, butanol, acetone, tetrahydrofuran, dimethylsiloxane, water, aliphatic hydrocarbons such as hexane, heptane, octane, decane, and dodecane, aromatic hydrocarbons, ketones, aldehydes, hydrocarbons, ethers, esters, glymes, aromatic hydrocarbons, halogen containing alcohols, alkyl nitriles, organic amines, fluorinated compounds, perfluorocarbons such as perfluorohexane and perfluoroheptane and mixtures thereof.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

Not applicable.

DETAILED DESCRIPTION OF THE INVENTION

The Present Invention comprises a process using a family of high-purity and low environmental impact solvents that can be used in a solvent purging process wherein the interior surface of high purity process piping containing a residual of a ultrahigh purity, low vapor pressure precursor for chemical vapor deposition (CVD) and other semiconductor manufacturing processes.
The Present Invention can be used in the apparatus of US Patent 5,964,230 of 12 October 1999 assigned to the assignee of the Present Invention, the text of which is incorporated expressly herein by reference.
The difficulty in the semiconductor industry is that ultra-low vapor pressure precursors chemicals cannot be removed from the interior of high purity process piping systems through the use of a standard vacuum cycle purge. The results of this incomplete removal include safety hazards for the operator, air and moisture reactivity of the precursor which may lead to a particulate generation and contamination or even more violent reactions. The highest solubility solvents for these materials are generally hydrocarbons and/or chlorofluorocarbons (CFCs) that are flammable, toxic, corrosive, reactive or have detrimental environmental effects. In cases such as ethanol, additional restrictions on shipping exist as a result of national and international regulations. In addition, since these precursor materials are usually air and/or moisture sensitive, as close to 100% removal from the inner walls of process piping as possible is required.
For the purposes of the Present Invention, hazardous process chemicals or source chemical precursors are those chemicals that meet established standards of governmental agencies such as the U.S. Environmental Protection Agency, as exemplified in the Barclays California Code of Regulations, Title 22, Section 66261.30-66261.33.
A large number of cleaning solvents have been identified in the last few years for use in applications involving cleaning of residuals from a number of items, as diverse as printed circuit boards to transmission fluid in automobiles. In these cases, the materials being cleaned off are waste byproducts, not ultra-pure precursors inside of process chemical delivery lines that also must remain ultrapure.
While many compounds have been tried, the inventors have yet to find in the current literature, a combination of this process and appropriate solvent or solvent blends. The Present Invention is directed to the use of blended solvents, as well as pure solvents that meet the safety, process and environmental concerns required by the semiconductor industry and health and zoning regulations. The blends preferably include perfluorocarbons as carrier solvents, and in some cases as the primary solvents, also, as well as hydrocarbon solvents of suitable solubility and vapor pressures and flash points. Pure materials will include all types of non-flammable or combustible alcohols, ethers, acetone and other polar and non-polar solvents, and their mixtures, both with each other and with inert carrier solvents. Additionally, supercritical fluids, such as liquid CO₂ can be used and are contemplated.
In a preferred embodiment using the solvent purge apparatus of US Patent 5,964,230, the bulk of the process chemical precursor is purged with an inert gas (Helium, nitrogen, argon, or other suitable inert gas) from the delivery line region that requires the purge operation, leaving only the residual process chemical precursor that sticks to the walls of the tubing.
A vacuum is applied to the internal region of the solvent purge apparatus to be purged.
A solvent, consisting of a bulk carrier perfluorohexane or similar material, and a hydrocarbon solvent, such as hexane or heptane, or a single material non-blended solvent, is injected under pressure into the purge region. Note that a pure solvating material that meets the criteria of safety and environment concerns, as well permitting the easy dissolution of the precursor is an acceptable alternative solvent for this application.
The contaminated solvent then is directed to a capture vessel, that may optionally contain a carbon or other absorbent media or it is directed to a vent to a abatement system. The selection of the absorbent media is directly related to the flammability, reactivity, toxicity and corrosivity of the precursors and the solvent mixture, and must be determined by testing.
The solvent washing of the interior of the piping is repeated until all evidence of precursor is removed. This solvent washing will be described further below.
The process chemicals or high purity source chemicals include but not limited to: tantalum pentaethoxide (TAETO), tetrakis(diethylamino) titanium (TDEAT), tetrakis(dimethylamino) titanium (TDMAT), copper hexafluoroacetylacetonate-trimethylvinylsilane (Cu(hfac)TMVS) and similar CVD copper precursors, tetraethylorthosilicate (TEOS) and other chemical vapor deposition (CVD) silicon precursors such as tetramethylcyclotetrasiloxane (TMCTS), boron and phosphorus containing CVD precursors such as trimethylborate (TMB), triethylborate (TEB), trimethylphosphite (TMPi), and triethylphosphate (TEPO), bistertiarybutylaminosilane (BTBAS), tantalum tetraethoxidedimethylaminoethoxide (TAT-DMAE), t-butylimidotrisdiethylamido tantalum (TBTDET), triethyl arsenate (TEASAT) and similar arsenic precursors such as triethyl arsenite (TEOA), low-K spin on materials such as VELOX polyarylene ethers available from Air Products and Chemicals, Inc. of Allentown, PA, FLARE fluorinated arylene ethers available from Honeywell, Morrisville, N.J., SILK aromatic hydrodcarbon resins available from Dow Chemical of Midland, Michigan, and other related compounds, where rapid, complete removal of the process chemical benefits from washing of the process piping with a suitable solvent.
On a broad basis, the solvent(s) contemplated by the present invention comprises organic alcohols such as methanol, ethanol, propanol, butanol, acetone, tetrahydrofuran, dimethylsiloxane, water, aliphatic hydrocarbons such as hexane, heptane, octane, decane, and dodecane, aromatic hydrocarbons, ketones, aldehydes, hydrocarbons, ethers, esters, glymes, aromatic hydrocarbons, halogen containing alcohols, alkyl nitriles, alkanols, organic amines, fluorinated compounds and perfluorocarbons perfluorohexane, perfluoroheptane and mixtures thereof.
Hydrocarbons are desirable primary solvents, such as those derived from petroleum and agricultural feedstocks; alcohols; glycols; glycol ethers; esters; aldehydes; ketones; ethers; halogenated hydrocarbons; nitrogen compounds; sulfur compounds; silicone compounds; normal heptane; 2- and 3-methylhexane; 2,3- and 3,3-dimethylpentane; 2,4- and 2,2-dimethylhexane; dimethylcyclopentane; methylcyclohexane; and ethylpentane. Other hydrocarbons such as n-pentane; 2-methylbutane; 2,2-dimethylpropane; n-hexane; 3-methylpentane; 2,2-dimethylbutane; 2,3-dimethylbutane; n-heptane; 2-methylhexane; 3-methylhexane; 2,3-dimethylpentane; 2,4-dimethylpentane; n-octane; 2,2,3-trimethylpentane; 2,2,4-trimethylpentane; cyclopentane; cyclohexane; methylcyclohexane; and ethylcyclohexane; chlorinated hydrocarbons such as dichloromethane cis-1,2-dichloroethylene can be contemplated.
Aromatic, carboxylic, halogenated, nitrogen and oxygen containing solvents are also contemplated such as, trans-1,2-dichloroethylene; trichloroethylene; and tetrachloroethylene; ketones such as acetone; methyl ethyl ketone; methyl butyl ketone; and methyl isobutyl ketone; ethers such as diethyl ether; methyl cellosolve; tetrahydrofuran; and 1,4-dioxane; chlorofluorohydrocarbons such as 2,2-dichloro-1,1,1-trifluoroethane; and 1,1-dichloro1-fluoroethane; and esters such as methyl acetate; ethyl acetate; propyl acetate; and butyl acetate; nitro compounds such as nitromethane; nitroethane; nitropropane; and nitrobenzene; amines such as diethylamine; triethylamine; i-propylamine; n-butylamine; and i-butylamine; phenols such as phenol; o-cresol; m-cresol; p-cresol; thymol; p-t-butylphenol; t-butylcatechol; catechol; isoeugenol; o-methoxyphenol; bisphenol A; isoamyl salicylate; benzyl salicylate; methyl salicylate and 2,6-di-t-butyl-p-cresol; and triazoles; such as as 2-(2'-hydroxy-5'-methyl-phenyl) benzotriazole; 2-(2'-hydroxy-3'-t-buthyl-5'-methylphenyl)-5-chlorobenzotriazole; 1,2,3-benzotriazole and 1-[(N,N-bis-2-ethylhexyl)aminomethyl]benzotriazole; alcohols selected from the group consisting of 1-butanol; 2-butanol; ethanol; 2-methyl-1-propanol; 2-methyl-2-propanol; 1-pentanol; 2-pentanol; 1-propanol; and 2-propanol; esters; hydrocarbons selected from the group consisting of butane; cyclopropane; decane; 2,3-dimethylpentane; 2,4-dimethylpentane; 2,2-dimethylpropane; heptane; isobutane; limonene; 2-methylbutane; 3-methylhexane; 3-methylpentane; nonane; octane; pentane; pinene; propane; turpentine and undecane.
Solvents useful especially for blending to reduce flammability or hazardous conditions include perfluorocarbons such as decafluorobutane; dodecafluoropentane; hexafluorocyclopropane; hexafluoroethane; octafluorocyclobutane; octafluoropropane; tetradecafluorohexane; and tetrafluoromethane; 1,1,1,2,2-pentafluorobutane; 1,1,1,2,2-pentafluoropentane; 2-methyl-3,3,4,4,4-pentafluorobutane; 2-trifluoromethyl-1,1,1,2-tetrafluorobutane; 1,1,1,2,2,3,3-heptafluoropentane; 1,1,1,2,2,3,3,-heptafluorohexane; 2-trifluoromethyl-1,1,1,2-tetrafluoropentane; 4-methyl-1,1,1,2,2,3,3-heptafluoropentane; 3-methyl-2-trifluoromethyl-1,1,1,2-tetrafluorobutane; 1,1,1,2,2,3,3,4,4-nonafluorohexane; 2-trifluoromethyl-1,1,1,2,3,3-hexafluoropentane; 2,2-(bis)trifluoromethyl-1,1,1-trifluorobutane; 1,1,1,2,2,3-hexafluoro-3-trifluoromethylpentane; 1,1,1,2,2,3,3,4,4-nonafluoroheptane; 5-methyl-1,1,1,2,2,3,3,4,4-nonafluorohexane; 2-trifluoromethyl-1,1,1,2,3,3-hexafluorohexane; 4-methyl-2-trifluoromethyl-1,1,1,2,3,3-hexafluoropentane; 2,2-trifluoromethyl-1,1,1-trifluoropentane; 3-methyl-2,2-trifluoromethyl-1,1,1-trifluorobutane; 1,1,1,2,2,3-hexafluoro-3-trifluoromethylhexane; 1,1,1,2,2,3-hexafluoro-3-trifluoromethyl-4-methylpentane; 2-trifluoromethyl-2-fluoropropane; 2-methyl-1,1,1,2-tetrafluorobutane; 3-methyl-1,1,1,2,2,3-hexafluoropentane; 4-methyl-1,1,1,2,2,3,3,4-octafluorohexane; 3-methyl-2-trifluoromethyl-1,1,1,2,3-pentafluoropentane; 2-methyl-1,1,1,3,3,4,4,4-octafluorobutane; 3-methyl-1,1,1,2,2,4,4,5,5,5-decafluoropentane; 2-methyl-1,1,1,3,3,4,4,5,5,5-decafluoropentane; 3-trifluoromethyl-1,1,1,2,2-pentafluoropentane; 3-pentafluoroethyl-1,1,1,2,2-pentafluoropentane; 4-trifluoromethyl-1,1,1,2,2,3,3-heptafluorohexane; 2-methyl-2-trifluoromethyl-1,1,1-trifluoropropane; 2-methyl-2-trifluoromethyl-3,3,4,4,4-pentafluorobutane; 2-methyl-2-trifluoromethyl-1,1,1-trifluorobutane; 3,3-dimethyl-1,1,1,2,2,4,4,5,5,5-decafluoropentane; 3-methyl-3-trifluoromethyl-1,1,1,2,2-pentafluoropentane; 3,3-bis(trifluoromethyl)pentane; 2,2-dimethyl-1,1,1,3,3,4,4,5,5,5-decafluoropentane; 2-methyl-2-trifluoromethyl-1,1,1-trifluoropentane;
Note also that process chemicals that are reactive, but provide soluble byproducts are also amenable to the present invention, and that the term solvent, in the present invention, is also contemplated in the broad definition of a "solvent" for purposes of the present invention. Included in this category of reactive "solvents" are acids, bases, and reactive solvents. Specific examples are; the use of ethanol with TDEAT, in which titanium ethoxide is produced, and which is soluble in ethanol, ensuring complete removal. Use of nitric acid solutions can be used to remove copper oxidation byproducts, while HF solutions can be used to remove oxidation byproduct materials, such as titanium oxide or tantalum oxide. Such reactive source chemical "solvents" are broadly contemplated as a quantity of source chemical acids or bases, that act in combination as a solvent for the high purity source chemical, or that may react with the high purity source chemical to create high solubility byproducts. This group may comprise HF, HNO₃, HCI, H₂SO₄, NaOH, KOH, and various other oxidizing and/or reducing agents, as well as organic acids and alkalis that are suitable for reacting or removing the precursor material.
Additionally, the solvent may render the high purity chemical inert or at least non-flammable when mixed together in the manifold. It is envisioned that various fluorinated and perfluorinated organic or hydrocarbon liquids would be included in such class of solvents. Perfluorocarbons, such as; perfluorohexane, perfluoroheptane and mixtures thereof are exemplary of such solvents. Additionally, inert compounds such as vacuum pump oils and/or similar low volatility hydrocarbon or fluorocarbon oils may be used.
Perfluorohexane is proposed as one bulk carrier solvent. This should be kept at a minimum of water and dissolved oxygen. The removal of water and oxygen from perfluorocarbon solvents is well known and not claimed. A number of perfluorocarbon compounds can be used alternatively in this context, as long as they meet the general criteria: non-flammable or easily made non-flammable; miscible in primary solvent; nonreactive to the precursor; easily recovered for recycling; not an environmental threat.
The primary solvent must be selected as a direct function of: it's capacity to absorb or solvate the precursor in question, its volatility, which must be greater than supplied vacuum capabilities, and it's flash point, which must be as high as practical. These conditions may vary from precursor to precursor, requiring a variety of primary solvents to make the process work. For example, TDMAT and TDEAT use hexane or heptane as primary solvents. Copper CVD precursors, such as Cu(hfac)tmvs use trimethylvinylsilane (TMVS) as the primary solvent. The solvent materials may be selected to remove a variety of precursors, including, but not necessarily limited to, tantalum precursors such as TAETO and TBTDET; titanium precursors, such as TDEAT, and TDMAT; Copper precursors, including Cu(hfac)tmvs, and any other copper containing precursor where the olefin group may be used as a solvent; barium/strontium/titanium (BST) precursors, which are typically solid in nature and use a variety of solvents as precursor carriers, examples of precursors include Ba(thd)_x, Sr(thd)_x and Ti(thd)_x. Arsenic bearing compounds, such as TEASAT and TEOA may also be purged from the interior of high purity process piping using these techniques. Germanium, Hafnium, niobium, strontium and other associated liquid precursors may also be removed using this technique with suitable solvating agents, depending on the exact compound in use.
Frequently, the primary solvent will be one of the components parts of the precursor molecule. Still other precursors may use alcohols as primary solvents, such as ethanol, isopropanol, or methanol. In all cases, the primary issues are precursor solubility, non-reactivity of the solvent with the precursor of carrier solvent. The primary solvents in use with TDMAT, for example are hexane and heptane.
The operating limits of the solvent are based on the boiling and flash points of the solvent mixture, and of the viscosity and phase of the precursor. Temperatures as high as 80°C are acceptable, as well as down to about 0°C, depending on the solvent and the precursor. The purge gas or solvent delivery pressure range is preferably from 5 psig to 70 psig, although unpressurized inert gas delivery is also contemplated. Therefore, for the purpose of the present invention, purging is deemed to include subatmospheric, atmospheric or super atmospheric inert gas addition by using vacuum in the manifold to introduce inert gas or by using a source of elevated pressure inert gas. Pressurizing is deemed to include the use of an elevated pressure source of inert gas where the pressure at least rises from the evacuated condition and preferably becomes superatmospheric. The vacuum required must be below that of the vapor pressure of the two solvents, in order to guarantee complete removal.
The range of blends preferably is from 1% to 20% by weight of the primary solvent in the second or fluorine containing solvent, and the selection of blend is based on the blend's potential for flammability, the solubility of the precursor in the solvent, and the number of cycles run by the apparatus. In the preferred embodiment, the selected quantity of primary solvent, heptane, is 10% by weight, balance perfluorohexane.
In the use of the solvent cleaning process in conjunction with the traditional evacuation and purging with inert pressurizing gas, the removal of about 65-95% of source chemical precursor is realized in the first pass. Nearly all the rest is removed after the second cycle leaving only some small amount as residual. After the third solvent purge step, the precursor has been removed in it's entirety. In some cases, additional purges will be to used for confirmation of process completion, or in the event a lower concentration of solvent is used.
The present invention comprises a process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of the high purity source chemical through the manifold is discontinued, comprising; evacuating the manifold by connection to a source of vacuum, terminating the evacuation, introducing at least one solvent for the high purity source chemical into the manifold from at least one source of the at least one solvent, dissolving any residual high purity source chemical in the manifold into the at least one solvent and venting a resulting mixture of residual high purity source chemical and solvent from the manifold. Preferably, after venting the solvent, the process proceeds by purging by preferably pressurizing the manifold by connection to a source of preferably elevated pressure inert gas and then terminating the purging or preferably pressurizing.
Preferably the evacuating, introducing, dissolving, venting and purging or preferably pressurizing, are performed in a cyclic series of repetitions in which the process steps are repeated in sequence through a number of iterations to assure cleanliness. The inventors have found that in the experiments they conducted the steps of the process should be repeated three times. Preferably the cyclic series of repetitions is followed by evacuating and purging or preferably pressurizing the manifold prior to reintroduction of the process chemical or high purity source precursor into the manifold or piping. In most instances, it will be desirable that evacuating and purging or preferably pressurizing the manifold is terminated with evacuation of the manifold. The evacuation level should be below the vapor pressure of the solvent blend.
Alternatively, the present invention can avoid the prior evacuation, and merely drain the residual chemical from the manifold before solvent purging. In that instance, the invention is a process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of the high purity source chemical through the manifold is discontinued, comprising; draining the manifold by connection to a vent, introducing at least one solvent for the high purity source chemical into the manifold from at least one source of the at least one solvent, dissolving any residual high purity source chemical in the manifold into the at least one solvent and venting a resulting mixture of residual high purity source chemical and solvent from the manifold.
In the preferred embodiment, the solvent blend is in the ratio of approximately 1 to 20 percent heptane by weight, balance perfluorohexane, more preferably, the solvent blend is in the ratio of approximately 10 percent heptane by weight, balance perfluorohexane
The Present Invention provides a significant advantage in the use of high purity chemicals in a delivery system, such as in the electronics fabrication industry. Maintenance of the high purity of the source chemical requires not only the purity of the source chemical, but also the delivery system through which the chemical is dispensed. Traditionally, the industry has used multiple cycles of vacuum and purging with an inert pressurized gas to maintain cleanliness of the delivery system. However, with low volatility chemicals, such cyclic cleaning is not sufficient. Solvents for such low volatility chemicals are desirable. The Present Invention provides a unique process for providing such solvents and their disposal without adversely effecting the traditional way in which operators in the electronic fabrication industry utilize source chemicals. This provides essentially a seamless system for providing ultra cleanliness for even difficult source chemicals, such as low volatility chemicals and overcomes a long standing problem of sustaining purity of source chemicals through process lines and changeout of containers of such source chemicals and sequential use of different source chemicals in the same delivery system.
The Present Invention has been set forth with regard to several preferred embodiments, but the full scope of the invention should be ascertained from claims which follow.

Claims

A process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of said high purity source chemical through said manifold is discontinued, comprising; evacuating the manifold by connection to a source of vacuum, terminating said evacuation, introducing at least one solvent for said high purity source chemical into said manifold from at least one source of said at least one solvent, dissolving any residual high purity source chemical in said manifold into said at least one solvent, venting a resulting mixture of residual high purity source chemical and solvent from said manifold, purging said manifold by connection to a source of inert gas.
The process of Claim 1 wherein said evacuating, introducing, dissolving, venting and purging, are performed in a cyclic series of repetitions.
The process of Claim 2 wherein said cyclic series of repetitions is followed by evacuating and purging said manifold.
The process of Claim 3 wherein said evacuating and purging said manifold is terminated with evacuation of said manifold.
The process of Claim 1 wherein said at least one solvent is a fluorocarbon.
The process of Claim 5 wherein said fluorocarbon is a perfluoroperhydrocarbon.
The process of Claim 1 wherein said at least one solvent is a blend of a fluorocarbon containing solvent and a hydrocarbon solvent.
solvents and one solvent renders the high purity source chemical nonhazardous.
The process of Claim 1 wherein said high purity source chemical is selected from the group consisting of tantalum pentaethoxide (TAETO), tetrakis(diethylamino) titanium (TDEAT), tetrakis(dimethylamino) titanium (TDMAT), tetramethylcyclotetrasiloxane (TMCTS), copper hexafluoroacetylacetonate- trimethylvinylsilane (Cu(hfac)TMVS), tetraethylorthosilicate (TEOS), trimethylborate (TMB), triethylborate (TEB), trimethylphosphite (TMPi), triethylphosphate (TEPO), bistertiarybutylaminosilane (BTBAS), tantalumtetraethoxidedimethylaminoethoxide (TAT-DMAE), t-butylimidotrisdiethylamido tantalum (TBTDET), triethyl arsenite (TEOA), polyarylene ethers and mixtures thereof.
The process of Claim 1 wherein said at least one solvent is selected from the group consisting of organic alcohols such as methanol, ethanol, propanol, butanol, acetone, tetrahydrofuran, dimethylsiloxane, water, aliphatic hydrocarbons such as hexane, heptane, octane, decane, and dodecane, aromatic hydrocarbons, ketones, aldehydes, hydrocarbons, ethers, esters, glymes, aromatic hydrocarbons, halogen containing alcohols, alkyl nitriles, organic amines, fluorinated compounds, perfluorocarbons such as perfluorohexane and perfluoroheptane and mixtures thereof.
A process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of said high purity source chemical through said manifold is discontinued, comprising; evacuating the manifold by connection to a source of vacuum, terminating said evacuation, introducing a solvent blend of perfluorohexane and heptane for dissolving said high purity source chemical into said manifold from a source of said solvent blend, dissolving any residual high purity source chemical in said manifold into said solvent blend, venting a resulting mixture of residual high purity source chemical and solvent from said manifold and purging said manifold by connection to a source of inert gas.
The process of Claim 10 wherein said solvent blend is in the ratio of approximately 1 to 20 percent heptane by weight, balance perfluorohexane.
The process of Claim 10 wherein said solvent blend is in the ratio of approximately 10 percent heptane by weight, balance perfluorohexane.
A process for cleaning a manifold which delivers high purity source chemical from a high purity source chemical container to a point of use after delivery of said high purity source chemical through said manifold is discontinued, comprising; draining the manifold by connection to a vent, introducing at least one solvent for said high purity source chemical into said manifold from at least one source of said at least one solvent, dissolving any residual high purity source chemical in said manifold into said at least one solvent and venting a resulting mixture of residual high purity source chemical and solvent from said manifold.
The process of Claim 13 wherein said at least one solvent is a fluorocarbon.
The process of Claim 14 wherein said fluorocarbon is a perfluoroperhydrocarbon.
The process of Claim 13 wherein said at least one solvent is a blend of a fluorocarbon containing solvent and a hydrocarbon solvent.