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`US 20090120457Al
`
`c19) United States
`c12) Patent Application Publication
`Naghshineh et al.
`
`c10) Pub. No.: US 2009/0120457 Al
`May 14, 2009
`(43) Pub. Date:
`
`(54) COMPOSITIONS AND METHOD FOR
`REMOVING COATINGS AND PREPARATION
`OF SURFACES FOR USE IN METAL
`FINISHING, AND MANUFACTURING OF
`ELECTRONIC AND MICROELECTRONIC
`DEVICES
`
`(75)
`
`Inventors:
`
`Shahriar Naghshineh, Allentown,
`PA (US); Kevin Yanders,
`Germansville, PA (US); Ewa
`Oldak, Fountain Hill, PA (US);
`George Schwartzkopf,
`Washington, NJ (US)
`
`Correspondence Address:
`DESIGN IP, P.C.
`5100 W. TILGHMAN STREET, SUITE 205
`ALLENTOWN, PA 18104 (US)
`
`(73)
`
`Assignee:
`
`SURFACE CHEMISTRY
`DISCOVERIES, INC., Bethlehem,
`PA (US)
`
`(21)
`
`Appl. No.:
`
`12/266,954
`
`(22)
`
`Filed:
`
`Nov. 7, 2008
`
`Related U.S. Application Data
`
`(60) Provisional application No. 61/002,598, filed on Nov.
`9, 2007.
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`C23G 1114
`G03F 7142
`
`(2006.01)
`(2006.01)
`
`(52) U.S. Cl. ............................................. 134/2; 510/176
`
`(57)
`
`ABSTRACT
`
`Improved cleaning compositions for removing particles,
`organic contamination, photoresist, post-ash residue, coat(cid:173)
`ings, and other materials from metal and silicon surfaces
`including substrates present during the manufacture of inte(cid:173)
`grated circuits, liquid crystal displays, and photovoltaic
`devices. The cleaning and surface preparation compositions
`comprise one or more water soluble strongly basic compo(cid:173)
`nents, one or more water soluble organic amines, one or more
`water soluble oxidizing agents, balance water. Optional com(cid:173)
`ponents can include corrosion inhibitors, surfactants and
`chelating agents.
`
`TOK Ex. 1021
`PGR Petition
`
`

`

`Patent Application Publication May 14, 2009 Sheet 1 of 4
`
`us 2009/0120457 Al
`
`Fig. lA
`
`Fig. 1B
`
`Page i
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`

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`Patent Application Publication May 14, 2009 Sheet 2 of 4
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`US 2009/0120457 Al
`
`Fig. 2A
`
`Fig. 2B
`
`Page ii
`
`

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`Patent Application Publication May 14, 2009 Sheet 3 of 4
`
`US 2009/0120457 Al
`
`Fig. 3A
`
`Fig. 3B
`
`Page iii
`
`

`

`Patent Application Publication M ay 14, 2009 Sheet 4 of 4
`
`US 2009/0120457 Al
`
`Fig. 4A
`
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`
`Page iv
`
`

`

`US 2009/0120457 Al
`
`May 14, 2009
`
`1
`
`COMPOSITIONS AND METHOD FOR
`REMOVING COATINGS AND PREPARATION
`OF SURFACES FOR USE IN METAL
`FINISHING, AND MANUFACTURING OF
`ELECTRONIC AND MICROELECTRONIC
`DEVICES
`
`CROSS REFERENCE TO RELATED
`APPLICATION(S)
`
`[0001] This application claims priority from U.S. Patent
`Application No. 61/002,598 filed Nov. 9, 2007, which is
`incorporated by reference as if fully set forth.
`
`FIELD OF INVENTION
`
`[0002] The present invention pertains to removing par(cid:173)
`ticles, organic contamination, photoresist, post-ash residue,
`coatings, and other materials from metal and silicon surfaces
`including substrates present during the manufacture of inte(cid:173)
`grated circuits, liquid crystal displays, and photovoltaic
`devices.
`
`BACKGROUND OF THE INVENTION
`
`[0003] The fabrication of integrated circuits (IC) and other
`electronic devices such as photovoltaic cells incorporates
`scores of cleaning sequences involving a large number of
`toxic, flammable, explosive, and environmentally hazardous
`chemicals. These include hydrogen fluoride, hydroxylamine,
`phenols, strong acids, and a broad range of organic solvents.
`Many of these cleaning agents are also widely used for metal
`surfaces in variety of applications including exterior aircraft
`cleaning, metal parts degreasing, and engine maintenance.
`[0004] An integral part of microelectronic fabrication is the
`use of photoresists to transfer an image from a mask or reticle
`to the desired circuit layer. After the desired image transfer
`has been achieved, the photoresist is removed by "stripping"
`before proceeding to some subsequent process step. A wide
`variety of photoresist compositions must be removed in this
`way. These include highly ion implanted positive photoresists
`that are present during IC gate fabrication and also the very
`thick negative photoresists used for solder bump placement.
`Typically, organic solvent mixtures are utilized for this pho(cid:173)
`toresist removal step.
`[0005] Alternatively, the bulk of the photoresist may be
`removed by treating with a plasma. This "ashing" process
`typically utilizes an oxygen plasma. During an ashing pro(cid:173)
`cess, any metal-containing residues are oxidized and made
`more difficult to remove. Thus the cleaning solvents used for
`this purpose additionally contain fluorides, hydroxylamine,
`phenols, or amines which are needed to effectively remove
`post-ash residue.
`[0006] Modem integrated circuit (IC) manufacturing also
`utilizes multiple chemical mechanical polishing (CMP) steps
`for each device. The chemical mechanical polishing pro(cid:173)
`cesses involve holding and rotating a thin, flat substrate of the
`semiconductor material against a wetted polishing surface
`under controlled chemical, pressure and temperature condi(cid:173)
`tions. A chemical slurry containing a polishing agent, such as
`alumina or silica, is used as the abrasive material. Unfortu(cid:173)
`nately, chemical mechanical polishing processes leave con(cid:173)
`tamination on the surfaces of the semiconductor substrate,
`which, like photoresist, must be removed before further
`elaboration of the integrated circuit. Alkaline solutions based
`
`on ammonium hydroxide have been traditionally used in
`post-chemical mechanical polishing cleaning applications.
`[0007] U.S. Pat. No. 5,863,344, discloses a cleaning solu(cid:173)
`tion for semiconductor devices containing tetramethyl
`ammonium hydroxide, acetic acid, and water. The solution
`preferably contains a volumetric ratio of acetic acid to tet(cid:173)
`ramethyl ammonium hydroxide ranging from about 1 to
`about 50.
`[0008] U.S. Pat. No. 5,597,420, discloses a post etch aque(cid:173)
`ous stripping composition useful for cleaning organic and
`inorganic compounds from a substrate that will not corrode or
`dissolve metal circuitry in the substrate. The aqueous com(cid:173)
`position contains preferably 70 to 95 wt % monoethanola(cid:173)
`mine and a corrosion inhibitor at about 5 wt % such as cat(cid:173)
`echol, pyrogallol or gallic acid.
`[0009] U.S. Pat. No. 5,466,389, discloses an aqueous alka(cid:173)
`line cleaning solution for cleaning microelectronic sub(cid:173)
`strates. The cleaning solution contains a metal ion-free alka(cid:173)
`line component such as a quaternary ammonium hydroxide
`(up to 25 wt%), a nonionic surfactant (up to 5 wt%), and a
`pH-adjusting component, such as acetic acid, to control the
`pH within the range of 8 to 10.
`[0010] U.S. Pat. No. 5,563,119 discloses a post etch aque(cid:173)
`ous stripping composition consisting of an alkanolamine,
`tetraalkyammonium hydroxide, and a corrosion inhibitor for
`cleaning organic residue from aluminized inorganic sub(cid:173)
`strates.
`[0011] U.S. Pat. No. 6,194,366 discloses post-CMP clean(cid:173)
`ers comprising a quaternary ammonium hydroxide, an
`alkanolamine, and a corrosion inhibitor.
`[0012] U.S. Pat. No. 7,365,045 discloses cleaning solutions
`consisting of a quaternary ammonium hydroxide, an organic
`amine, and water with pH greater than 10.
`[0013] Those concerned with the development of surface
`cleaning and preparation technology have continuously
`sought cleaning techniques that avoid the use of hazardous
`materials, e.g., solvents, phenols, hydroxylamine, fluorides,
`and other hazardous and environmentally unacceptable com(cid:173)
`ponents.
`
`SUMMARY OF THE INVENTION
`
`[0014]
`In accordance with the present invention, composi(cid:173)
`tions and methods of use are provided for removing particles,
`organic contamination, photoresist, post-ash residue, coat(cid:173)
`ings, and other materials from metal and silicon surfaces
`including substrates present during the manufacture of inte(cid:173)
`grated circuits, liquid crystal displays, and photovoltaic
`devices. The cleaning and surface preparation compositions
`comprise one or more water soluble strongly basic compo(cid:173)
`nents capable of producing a pH greater than 10, one or more
`water soluble organic amines, one or more water soluble
`oxidizing agents, and water. The compositions may option(cid:173)
`ally also contain corrosion inhibitors, surfactants, and chelat(cid:173)
`ing agents to further enhance performance. The method of the
`invention comprises contacting a coated substrate with a
`cleaning composition with optional heating and/or the appli(cid:173)
`cation of sonic energy.
`[0015] Cleaning compositions according to the present
`invention have very high water content (up to about 99.7 wt
`% ) resulting in low cost cleaners that may be safely trans(cid:173)
`ported and dispensed, and the safe disposal of which may
`consist of discharge to an appropriate industrial drain without
`any additional pretreatment.
`
`

`

`US 2009/0120457 Al
`
`May 14, 2009
`
`2
`
`[0016] Compositions according to the present invention
`have the following advantages over compositions of the prior
`art, namely;
`[0017]
`(a) have a high water concentration resulting in
`low cost and negligible environmental impact;
`[0018]
`(b) are not subject to performance deviations
`caused by incidental water absorbed from the atmo(cid:173)
`sphere or otherwise present;
`[0019]
`( c) do not contain hydrofluoric acid or salts
`thereof,
`[0020]
`( d) do not contain solvents classified as hazardous
`air pollutants (HAPs ), such as glycol ethers;
`[0021]
`( e) do not contain hydroxylamine, a widely used
`but hazardous component of a microelectronics cleaner;
`[0022]
`(f) are useful for removing coatings, photopoly(cid:173)
`mers and photoresists as required for a very wide range
`oflithographic processes including the removal of thick
`photopolymers from solder bumps;
`[0023]
`(g) are useful for removing residues and particles
`from microelectronic substrates and nano-structures
`after etching and ashing;
`[0024]
`(h) are useful for cleaning microelectronic sub(cid:173)
`strates
`and nano-structures
`following
`chemical
`mechanical polishing (CMP);
`[0025]
`(i) are useful for cleaning silicon photovoltaic
`substrates; and
`[0026] G) are useful for a variety of metal cleaning appli-
`cations.
`[0027] The ability of compositions according to the inven(cid:173)
`tion, which may contain greater than 99% water, to remove
`organic polymer photoresists is unexpected. Typically sol(cid:173)
`vent mixtures are used for this purpose. The water content of
`such solvent mixtures must be minimized to maintain photo(cid:173)
`resist removal efficiency. With the compositions according to
`the present invention, photoresist removal is facilitated by the
`presence of the oxidizing component.
`[0028] Compatibility of organic amines of the invention
`with strong oxidizing agents is also unexpected since the
`oxidation of amines to substituted hydroxylamines, nitrones,
`and the like is normally considered to be facile. Another
`unexpected but useful feature of the compositions of the
`invention is the reduced solder etch rates resulting from the
`inclusion of an oxidizing component. Yet another unexpected
`but useful feature of compositions according to the invention
`is the reduced silicon wafer etch rates resulting from the
`inclusion of the oxidizing component.
`[0029] Therefore, in one aspect the present invention is a
`liquid cleaning composition for removing particles, organic
`contamination, photoresist, post-ash residue, coatings, and
`other materials from metal and silicon surfaces comprising
`0.1 to 10% by volume of a water soluble strong base, 0.1 to
`20% by volume water soluble organic amine, 0.1 to 10% by
`volume water soluble oxidizing agent, balance water.
`[0030]
`In another aspect, the present invention is a method
`for cleaning contaminants being one of, particles, organic
`contamination, post-ash residue, coatings and other materials
`from metal and silicon surfaces comprising the steps of
`exposing a surface coating of one or more of said contami(cid:173)
`nants to a composition consisting of0.1 to 10% by volume of
`a strong base, 0.1 to 20% by volume water soluble organic
`amine, 0.1 to 10% by volume water soluble oxidizing agent,
`balance water at a temperature of from 10° C. to 85° C. for a
`
`period of time from ten seconds to sixty minutes; and rinsing
`said surface in de-ionized water.
`
`BRIEF DESCRIPTION OF THE DRAWING(S)
`
`[0031] FIG. lA is a scanning electron microscope (SEM)
`photomicrograph of a patterned thick photopolymer resist
`with deposited solder bumps.
`[0032] FIG. 1B is a SEM photomicrograph of the device of
`FIG. lA after removal of the photoresist with a composition
`according to the present invention.
`[0033] FIG. 2A is an optical photomicrograph of a pat(cid:173)
`terned thin photoresist that was impossible to remove using
`typical solvent mixtures.
`[0034] FIG. 2B is an optical photomicrograph of the device
`ofFIG. 2A after stripping with a composition according to the
`present invention.
`[0035] FIG. 3A is a SEM photomicrograph of a thick nega(cid:173)
`tive photoresist deposited onto under bump metal (UBM),
`patterned, and then deposited with a tin-lead eutectic solder
`giving solder bumps over UBM.
`[0036] FIG. 3B is a SEM photomicrograph of the device of
`FIG. 3A after removal of the photoresist with a composition
`according to the present invention.
`[0037] FIG. 4A is a SEM photomicrograph of a thick nega(cid:173)
`tive photoresist deposited onto under bump metal (UBM),
`patterned, and then deposited with a high lead solder giving
`solder bumps over UBM.
`[0038] FIG. 4B is a SEM photomicrograph of the device of
`FIG. 4A after removal of the photoresist with a composition
`according to the present invention.
`
`DETAILED DESCRIPTION OF THE PREFERRED
`EMBODIMENT(S)
`
`[0039] The present invention provides new aqueous com(cid:173)
`positions for stripping or cleaning metal and silicon surfaces
`including substrates present during the manufacture of inte(cid:173)
`grated circuits, liquid crystal displays, and photovoltaic
`devices that comprise one or more water soluble strongly
`basic components capable of producing a pH greater than 10,
`preferably greater than 12, one or more water soluble organic
`amines, one or more water soluble oxidizing agents, and
`water. The compositions may optionally also contain corro(cid:173)
`sion inhibitors, surfactants, and chelating agents to further
`enhance performance. These compositions may be prepared
`by blending or mixing components of the composition
`according to any method known in the art.
`[0040] Preferably, compositions according to the present
`invention comprise from about 0.1% to about 10% of water
`soluble strongly basic components, from about 0.1 % to about
`20% of water soluble organic amines, from 0.1 % to about
`10% of water soluble oxidizing agents, balance of water.
`More preferably, these compositions comprise from about
`1 % to about 10% of water soluble strongly basic components,
`from about 1 % to about 10% of water soluble organic amines,
`from about 0.1 % to about 5% of water soluble oxidizing
`agents, and the balance of water.
`[0041] The water soluble strongly basic components may
`comprise any number of bases. Preferably, the water soluble
`strong base is quaternary ammonium hydroxide, such as tet(cid:173)
`raalkyl ammonium hydroxides (including hydroxyl- and
`alkoxy-containing alkyl groups generally from 1 to 4 carbon
`atoms in the alkyl or alkoxy group) or a metal hydroxide such
`as potassium hydroxide. The most preferable of these bases
`
`

`

`US 2009/0120457 Al
`
`May 14, 2009
`
`3
`
`are tetramethyl ammonium hydroxide, tetrabutyl ammonium
`hydroxide, and potassium hydroxide. Examples of other
`usable quaternary ammonium hydroxides include: benzyltri(cid:173)
`methyl ammonium hydroxide,
`trimethyl-2-hydroxyethyl
`ammonium hydroxide (choline), trimethyl-3-hydroxypropyl
`ammonium hydroxide, trimethyl-3-hydroxybutyl ammo(cid:173)
`nium hydroxide,
`trimethyl-4-hydroxybutyl ammonium
`hydroxide, triethyl-2-hydroxyethyl ammonium hydroxide,
`tripropyl-2-hydroxyethyl ammonium hydroxide, tributyl-2-
`hydroxyethyl ammonium hydroxide, dimethylethyl-2-hy(cid:173)
`droxyethyl ammonium hydroxide, dimethyldi(2-hydroxy(cid:173)
`ethyl)
`ammonium
`hydroxide,
`monomethyltri(2-
`hydroxyethyl) ammonium hydroxide, tetraethyl ammonium
`hydroxide, tetrapropyl ammonium hydroxide, monomethyl(cid:173)
`triethyl ammonium hydroxide, monomethyltripropyl ammo(cid:173)
`nium hydroxide, monomethyltributyl ammonium hydroxide,
`monoethyltrimethyl ammonium hydroxide, monoethyltribu(cid:173)
`tyl ammonium hydroxide, and the like and mixtures thereof.
`[0042] The water soluble organic amine components may
`comprise any number of amines. Preferably, the water soluble
`organic amine is 2-aminoethanol, 2-(2-aminoethylamino)
`ethanol, or 4-(3-aminopropyl)morpholine. Examples of other
`usable water soluble organic amines include: alkanolamines
`such as l-amino-2-propanol, l-amino-3-propanol, 2-(2-ami(cid:173)
`noethoxy)ethanol, 2-methylaminoethanol, 2-dimethylami(cid:173)
`noethanol, diethanolamine, triethanolamine, tris(hydroxym(cid:173)
`ethyl)-aminomethane,
`2-dimethylamino-2-methyl-1-
`propanol, and the like, and other strong organic bases such as
`guanidine,
`1,3-pentanediamine, 4-aminomethyl-1,8-oc(cid:173)
`tanediamine,
`2-aminoethylpiperazine,
`2-(2-aminoethy(cid:173)
`lamino )ethylamine, 1,2-diaminocyclohexane, tris(2-amino(cid:173)
`ethyl)amine, and 2-methyl-1,5-pentanediamine and mixtures
`thereof.
`[0043] The water soluble oxidizing agent component may
`comprise any number of oxidants. These oxidants facilitate
`the removal of organic coatings such as photoresists. Oxidiz(cid:173)
`ing agents also help to maintain a protective oxide surface
`layer on any sensitive materials present, particularly solder
`and silicon. Preferably, the water soluble oxidizing agent is
`hydrogen peroxide or N-methylmorpholine-N-oxide. Hydro(cid:173)
`gen peroxide is preferred because of its low cost, its availabil(cid:173)
`ity as a high purity reagent throughout the world, and because
`its only decomposition products are the environmentally
`friendly substances water and oxygen gas. Examples of other
`water soluble oxidizing agents useful for this purpose are:
`organic peracids, urea peroxide, and organic or inorganic
`perborates, percarbonates, or persulfates and mixtures
`thereof.
`[0044] These compositions may also be formulated with
`suitable water soluble corrosion inhibitors to further reduce
`the etch rates for any sensitive metals present, particularly
`aluminum or copper. Typical examples of water soluble cor(cid:173)
`rosion inhibitors useful for this purpose are: resorcinol, tria(cid:173)
`zoles, tetrazoles, 8-hydroxyquinoline, benzoic acid, and
`phthalic acids; and salts of the acids, anhydrides of the acids,
`or esters of the acids; and mixtures thereof. Additional water
`soluble corrosion inhibitors suitable for this purpose include
`boric acid, base soluble borate and silicate salts, polyhydroxy
`alcohols, such as ethylene glycol, propylene glycol, glycerol,
`and l-hydroxyalkyl-2-pyrrolidones such as 1-(2-hydroxy(cid:173)
`ethyl)-2-pyrrolidone and mixtures thereof.
`[0045] These compositions may also contain any suitable
`water-soluble amphoteric, non-ionic, cationic, or anionic sur(cid:173)
`factant. The addition of a surfactant reduces the surface ten-
`
`sion of the formulation and improves the wetting of the sur(cid:173)
`face to be cleaned and therefore improves the cleaning action
`of the composition.
`[0046] Amphoteric surfactants useful in these composi(cid:173)
`tions include betaines and sulfobetaines such as alkyl
`betaines, amidoalkyl betaines, alkyl sulfobetaines, and ami(cid:173)
`noalkyl sulfobetaines; aminocarboxylic acid derivatives such
`as amphoglycinates, amphopropionates, amphodiglycinates,
`and amphodipropionates; iminodiacids such as alkoxyalkyl
`iminodiacids; fluorinated alkyl amphoterics; and mixtures
`thereof.
`[0047] Non-ionic surfactants useful in these compositions
`include acetylenic dials, ethoxylated acetylenic dials, fluori(cid:173)
`nated alkyl alkoxylates, fluorinated alkylesters, fluorinated
`polyoxyethylene alkanols, aliphatic acid esters of polyhydric
`alcohols, polyoxyethylene monoalkyl ethers, polyoxyethyl(cid:173)
`ene dials, and siloxane type surfactants; and mixtures thereof.
`[0048] Anionic surfactants useful in these compositions
`include carboxylates, N-acylsarcosinates, sulfonates, fluoro(cid:173)
`alkyl sulfonates, sulfonic acids, sulfates, and mono- and
`diesters of orthophosphoric acid such as decyl phosphate, and
`mixtures thereof. Preferably, the anionic surfactants are
`metal-ion free sulfonic acids and sulfonic acid salts. Most
`preferably the anionic surfactants are dodecylbenzene(cid:173)
`sulfonic acid and ammonium lauryl sulfate.
`[0049] Cationic surfactants useful in the compositions
`include amine ethoxylates, dialkyldimethyl ammonium salts,
`dialkylmorpholinum salts, alkylbenzyldimethyl ammonium
`salts, alkyltrimethyl ammonium salts, and alkylpyridinium
`salts, and mixtures thereof.
`[0050] These compositions may also be formulated with
`suitable water soluble metal chelating agents to increase the
`capacity of the formulation to retain metals in solution and to
`enhance the dissolution of metallic residues on the surface,
`such as post-etch or post-CMP residues on microelectronic
`substrates or nanostructures. Metal chelating agents are also
`useful for stabilizing the water soluble oxidizing agents
`present in the compositions, particularly hydrogen peroxide.
`Typical examples of water soluble chelating agents useful for
`this purpose, known to those skilled in the art, include the
`following organic acids and their isomers and salts; ethylene(cid:173)
`diaminetetraacetic acid (EDTA), butylenediaminetetraacetic
`acid, cyclohexane-1,2-diaminetetraacetic acid (CyDTA),
`diethylenetriaminepentaacetic acid (DETPA), ethylenedi(cid:173)
`aminetetraproprionic acid,
`(hydroxy l)ethy lenediaminetri(cid:173)
`acetic acid (HEDTA), N,N,N',N'-ethylenediaminetetra (me(cid:173)
`thylenephosphonic)
`acid
`(EDTMP),
`triethylenetetraminehexaacetic acid (TTHA), 1,3-diamino-2-
`hydroxypropane-N,N,N',N'-tetraacetic acid (DHPTA), meth(cid:173)
`y liminodiacetic acid, propy lenediaminetetraacetic acid,
`nitrilotriacetic acid (NTA), citric acid, tartaric acid, gluconic
`acid, saccharic acid, glyceric acid, phthalic acid, maleic acid,
`mandelic acid, malonic acid, lactic acid, salicylic acid, and
`cystine. Preferred chelating agents are aminocarboxylic acids
`such as EDTA and CyDTA. Chelating agents of this class
`have a high affinity for the aluminum-containing residues
`typically found on microelectronic structures such as metal
`lines, vias, and pads, or nanostructures after dry etching and
`plasma ashing. The preferred chelating agent for hydrogen
`peroxide stabilization is CyDTA, which is highly valued
`because of its oxidation resistance and high affinity for per(cid:173)
`oxide destabilizing ions such as iron. Additional preferred
`chelating agents are the multi-carboxylic acids such as citric
`acid which have a high affinity for copper-containing residues
`
`

`

`US 2009/0120457 Al
`
`May 14, 2009
`
`4
`
`typically found on the surface of a microelectronic substrate
`or nano structures after a CMP process or in vias, trenches, or
`nanostructures after dry etching and plasma ashing.
`[0051] The present invention provides a user with a clean(cid:173)
`ing solution for removing an imaged thick dry film photore(cid:173)
`sist that remains after the deposition of solder bumps and
`subsequent heating to affect solder reflow. The composition
`of the cleaning solution consists of 0.1 to 10% by weight
`quaternary ammonium hydroxide, 0.1 to 20% by weight
`alkanolamine, 0 .1 to 10% hydrogen peroxide, balance water.
`Preferably, the pH of the solution is greater than 12.
`[0052] Another composition of the present invention pre(cid:173)
`sents a user with a cleaning solution for removing thick pho(cid:173)
`toresist that remains after the deposition of solder bumps onto
`imaged "under bump metal" solder pads. The composition of
`the cleaning solution consists of0.1 to 10% by weight potas(cid:173)
`sium hydroxide, 0.1 to 20% by weight alkanolamine, 0.1 to
`10% N-methylmorpholine-N-oxide, balance water. Prefer(cid:173)
`ably, the pH of the solution is greater than 12.
`[0053] Another cleaning solution according to the present
`invention is useful for removing up to 2.5 µm of hard baked
`photoresist from tetraethylorthosilicate (TEOS) dielectric.
`This composition consists of0.1 to 10% by weight quaternary
`ammonium hydroxide, 0.1 to 20% by weight alkanolamine,
`0.5 to 5% hydrogen peroxide, balance water. Preferably, the
`pH of the solution is greater than 12.
`[0054] Still another cleaning solution according to the
`present
`invention
`is useful for removing photoresist
`implanted with B+ and As+ ions consisting of0.1 to 10% by
`weight quaternary ammonium hydroxide, 0.1 to 20% by
`weight alkanolamine, 0.1 to 5% hydrogen peroxide, balance
`water. Preferably, the pH of the solution is greater than 12.
`[0055] Other compositions according to the present inven(cid:173)
`tion are used to remove organic impurities ( e.g., from copper
`surfaces typically present during the manufacture of inte(cid:173)
`grated circuits, or heterocyclic corrosion inhibitors such as
`benzotriazole and the like).
`[0056] Compositions according to the present invention are
`used to clean multi-crystalline silicon surfaces subsequent to
`phosphorous doping. Silicon cleaned in this way yields pho(cid:173)
`tovoltaic cells with higher efficiency.
`[0057] Compositions according to the present invention are
`used to remove grease and oils, sooty deposits and other
`impinged soils from a wide variety of metallic surfaces, espe(cid:173)
`cially aircraft exteriors.
`[0058] Compositions according to the present invention
`may be used at various concentrations to clean microelec(cid:173)
`tronic substrates containing integrated circuits or such sub(cid:173)
`strates that require cleaning before the integrated circuits are
`fabricated. When integrated circuits are present, the compo(cid:173)
`sitions remove metallic and organic contaminates, including
`particles, without damaging the integrated circuits. These
`compositions are particularly useful for the removal of
`organic coatings, e.g., photoresists. Multiple fabrication steps
`requiring the application, patterning, and removal of photo(cid:173)
`resists are typically used to manufacture integrated circuits.
`These compositions are useful for the removal of the gamut of
`photoresist chemistries including the highly implanted posi(cid:173)
`tive photoresists that occur during IC gate fabrication and
`ranging to the very thick negative photoresists used for solder
`bump placement.
`[0059] When used for cleaning microelectronic substrates
`or nanostructures, a contaminated substrate is exposed to
`compositions according to the invention for a time and at a
`
`temperature sufficient to clean unwanted contaminates from
`the substrate surface, rinsed with water, and dried. The sub(cid:173)
`strate can then be used for its intended purpose.
`[0060] A preferred method uses a bath or spray to expose
`the substrate to the composition. Bath or spray cleaning times
`are generally 1 minute to 60 minutes. Bath or spray cleaning
`temperatures are generally 10° C. to 85° C., preferably 20° C.
`to 75° C. The water soluble oxidizing agent may be injected
`at the point of use to preserve oxidizing ability at elevated
`temperatures.
`If required, the rinse times are generally 10 seconds
`[0061]
`to 5 minutes at room temperature, preferably 30 seconds to 2
`minutes at room temperature. Preferably de-ionized water is
`used to rinse the substrates although the use of an intermedi(cid:173)
`ate 2-propanol rinse may also be useful.
`If required, drying the substrates can be accom(cid:173)
`[0062]
`plished using any combination of air-evaporation, heat, spin(cid:173)
`ning, pressurized gas, or Marangoni effect driers. A preferred
`drying technique is spinning under a filtered inert gas flow,
`such as nitrogen, for a period of time until the wafer substrate
`is dry.
`[0063] Use of compositions according to the present inven(cid:173)
`tion provides effective cleaning of semiconductor wafer sub(cid:173)
`strates or nanostructures that have been previously oxygen
`plasma ashed to remove bulk photoresist, particularly wafer
`substrates containing a silicon, silicon dioxide, silicon
`nitride, silicon carbide, tungsten, tungsten alloy, titanium,
`titanium alloy, tantalum, tantalum alloy, copper, copper alloy,
`aluminum, or aluminum alloy film, and removes unwanted
`metallic and organic contaminates without causing unaccept(cid:173)
`able corrosion to the substrates.
`[0064] Use of compositions according to the present inven(cid:173)
`tion provides effective cleaning of semiconductor substrates
`or nano-structures that have been subjected to chemical
`mechanical polishing (CMP) and are contaminated with pol(cid:173)
`ishing slurry particles and residues. A variety of conventional
`cleaning tools, including Verteq single wafer megasonic
`Goldfinger, DDS ( double-sided scrubbers), single wafer spin
`wash, and megasonic batch wet bench systems may be uti(cid:173)
`lized effectively.
`[0065] Concentrates of compositions according to the
`present invention may be prepared by reducing the percent(cid:173)
`age of water noted in the composition described above. The
`resulting concentrates can later be diluted with an amount of
`water necessary to produce the desired cleaning composi(cid:173)
`tions.
`[0066] The following examples illustrate specific embodi(cid:173)
`ments of the invention described in this document. As would
`be apparent to skilled artisans, various changes and modifi(cid:173)
`cations are possible and are contemplated within the scope of
`the invention described.
`[0067] The components listed in Table I were combined
`with stirring to give each of the 19 homogeneous composi(cid:173)
`tions. The compositions of Examples 1-19 can optionally be
`formulated to include corrosion inhibitors, surfactants, or
`chelating agents.
`
`TABLE I
`
`Example
`
`Formulation
`
`la
`
`4.5 g 2-Arninoethanol (4.5%)
`2.5 g Tetramethylannnonium hydroxide (2.5%)
`1.0 g Hydrogen peroxide (1.0%)
`92 g water (92%)
`
`

`

`US 2009/0120457 Al
`
`May 14, 2009
`
`5
`
`TABLE I-continued
`
`TABLE I-continued
`
`Example
`
`Formulation
`
`Example
`
`Formulation
`
`lb
`
`2
`
`4
`
`7
`
`9
`
`10
`
`11
`
`12
`
`13
`
`14
`
`15
`
`16
`
`17
`
`18
`
`4.5 g 2-Arninoethanol (4.5%)
`2.5 g Tetramethylammonium hydroxide (2.5%)
`93 g water (93%)
`4.5 g 2-Arninoethanol (4.5%)
`2.5 g Tetramethylammonium hydroxide (2.5%)
`0.3 g Hydrogen peroxide (0.3%)
`92.7 g water (92.7%)
`4.5 g 2-Arninoethanol (4.5%)
`2.5 g Tetramethylammonium hydroxide (2.5%)
`0.5 g Hydrogen peroxide (0.5%)
`92.5 g water (92.5%)
`4.3 g 2-Arninoethanol (4.3%)
`2.4 g Tetramethylammonium hydroxide (2.4%)
`2.4 g Hydrogen peroxide (2.4%)
`90.9 g water (90.9%)
`4.5 g 2-Arninoethanol (4.3%)
`2.5 g Tetramethylammonium hydroxide (2.4%)
`4.0 g N-Methylmorpholine-N-oxide (3.9%)
`93 g water (89 .4%)
`4.5 g 2-Arninoethanol (2.2%)
`2.5 g Tetramethylammonium hydroxide (1.2%)
`4.0 g N-Methylmorpholine-N-oxide (1.9%)
`197 g water (94.7%)
`4.5 g 2-Arninoethanol (0.9%)
`2.5 g Tetramethylammonium hydroxide (0.5%)
`4.0 g N-Methylmorpholine-N-oxide (0.8%)
`509 g water (97.8%)
`4.5 g 2-Arninoethanol (0.8%)
`2.5 g Tetramethylammonium hydroxide (0.5%)
`8.0 gN-Methylmorpholine-N-oxide (1.4%)
`545 g water (97.3%)
`4.5 g 2-Arninoethanol (0.2%)
`2.5 g Tetramethylammonium hydroxide (0.1 %)
`4.0 g N-Methylmorpholine-N-oxide (0.2%)
`2170 g water (99.5%)
`4.5 g 2-Arninoethanol (4.5%)
`10 g Potassium hydroxide (10%)
`1.0 g N-Methylmorpholine-N-oxide (1.0%)
`84.5 g water (84.5%)
`0.1 g 2-Arninoethanol (0.1 %)
`10 g Potassium hydroxide (10%)
`1.0 g N-Methylmorpholine-N-oxide (1.0%)
`88.9 g water (88.9%)
`20 g 2-Arninoethanol (20%)
`1.0 g Potassium hydroxide (1.0%)
`1.0 g N-Methylmorpholine-N-oxide (1.0%)
`78 g water (78%)
`20 g 2-Arninoethanol (20%)
`1.0 g Potassium hydroxide (1.0%)
`0.1 g N-Methylmorpholine-N-oxide (0.1 %)
`78.9 g water (78.9%)
`4.5 g 2-Arninoethanol (4.5%)
`2.5 g Tetramethylammonium hydroxide (2.5%)
`10 g N-Methylmorpholine-N-oxide (10%)
`83 g water (83%)
`4.5 g 2-(