Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P70/00—Cleaning of wafers, substrates or parts of devices
  • H10P70/20—Cleaning during device manufacture
  • H10P70/27—Cleaning during device manufacture during, before or after processing of conductive materials, e.g. polysilicon or amorphous silicon layers
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
  • C11D1/38—Cationic compounds
  • C11D1/62—Quaternary ammonium compounds
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/22—Organic compounds
  • C11D7/32—Organic compounds containing nitrogen
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/26—Processing photosensitive materials; Apparatus therefor
  • G03F7/42—Stripping or agents therefor
  • G03F7/422—Stripping or agents therefor using liquids only
  • G03F7/425—Stripping or agents therefor using liquids only containing mineral alkaline compounds; containing organic basic compounds, e.g. quaternary ammonium compounds; containing heterocyclic basic compounds containing nitrogen
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/26—Processing photosensitive materials; Apparatus therefor
  • G03F7/42—Stripping or agents therefor
  • G03F7/422—Stripping or agents therefor using liquids only
  • G03F7/426—Stripping or agents therefor using liquids only containing organic halogen compounds; containing organic sulfonic acids or salts thereof; containing sulfoxides
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
  • C11D2111/10—Objects to be cleaned
  • C11D2111/14—Hard surfaces
  • C11D2111/22—Electronic devices, e.g. PCBs or semiconductors

Definitions

• This invention relates to a photoresist stripping solution and a method of stripping photoresists using the same.
• the invention is suitable for use in the fabrication of semiconductor devices such as ICs and LSIs, as well as liquid-crystal panel apparatus.
• the fabrication of semiconductor devices such as ICs and LSIs, as well as liquid-crystal panel apparatus comprises forming a uniform photoresist coating over conductive metallic layers, insulation layers such as an SiO 2 film formed on a substrate (silicon wafer) by CVD; performing selective exposure and development to form a photoresist pattern; selectively etching the substrate having the conductive metallic layers, the insulation layers formed thereon by CVD, using the photoresist pattern as a mask to thereby form a microcircuit; and then removing the unwanted photoresist layer with a stripping solution.
• copper metal wiring is generally formed by the dual damascene process. While various methods have been proposed to implement the dual damascene process, one example comprises the following: a Cu layer is formed on a substrate; a multiple of interlevel films, such as low-dielectric films (e.g. SOG film) and insulation films (e.g.
• SiN film and SiO 2 film are superposed on the Cu layer; a photoresist layer is provided on the topmost layer, and selectively exposed and developed to form a photoresist pattern; with this photoresist pattern used as a mask, the low-dielectric films, insulation films are etched and subjected to ashing treatment to strip away the photoresist pattern while forming via holes that connect to the Cu layer on the substrate; subsequently, another photoresist layer is formed on the topmost of the remaining superposed interlevel films and is selectively exposed and developed to form a new photoresist pattern; with this photoresist pattern used as a mask, a specified number of low-dielectric films, insulation films are etched, and subjected to ashing treatment to strip away the photoresist pattern while forming wiring grooves (trenches) that communicate with the above-described via holes; the via holes and wiring trenches are filled with Cu by plating or other method, thereby forming multiple layers of Cu wiring.
• Cu-based residues are prone to occur as the result of etching and ashing treatments that are effected to form the via holes; in addition, Si-based residues (Si deposition) originating from the low-dielectric films and insulation films are prone to occur as the result of etching and ashing treatments that are effected to form the wiring trenches, and the residues are occasionally formed as Si deposition around the opening of each trench. Unless the Cu and Si depositions are completely stripped away, problems will occur such as lower yield of semiconductor fabrication.
• the occurrence of Si-based residues (Si deposition) originating from the low-dielectric films and insulation films is not limited to the case of using the dual damascene process; they can occur in almost all cases of forming metal wiring on the substrate having Si-based interlevel films thereon.
• the photoresist stripping techniques are required to meet increasingly rigorous conditions in order to adjust for the decreasing feature size of patterns, the formation of more interlevel layers on the substrate and the changes in materials formed on the substrate surface.
• the photoresist stripping solution to be used must be not only easy to handle but also less hazardous in such terms as toxicity and explosiveness.
• a problem with the stripping solutions proposed in those patents is that if their ability to strip the photoresist film and post-ashing residues, particularly the ability to strip Si-based residues, is enhanced to an adequate level, they are not capable of providing adequate protection against corrosion of the Si substrate, particularly its reverse side; hence, the ability to strip the Si-based residues must be compromised to some extent.
• the present invention has been accomplished under these circumstances and has as an object of providing a photoresist stripping solution that is suitable for use in the photolithographic technology to form today's semiconductor and liquid-crystal display devices having an ever decreasing feature size and an increasing number of interlevel films superposed on the substrate, and that can assure effective protection of Al, Cu and other wiring metal conductors against corrosion as well as efficient stripping of the photoresist film, post-ashing residues and metal depositions.
• Another object of the invention is to provide a photoresist stripping solution that is particularly suitable for use in the formation of metal wiring on a substrate overlaid with Si-based interlevel films such as insulation films (e.g. SiO 2 film) and low-dielectric films (e.g. SOG film), and by means of which efficient stripping of Si-based residues originating from these Si-based interlevel films and effective protection of the substrate, particularly the reverse side of an Si substrate, from corroding can be accomplished in a balanced way.
• Si-based interlevel films such as insulation films (e.g. SiO 2 film) and low-dielectric films (e.g. SOG film)
• the present invention provides a photoresist stripping solution comprising (a) a quaternary ammonium hydroxide of the following general formula (I):
• R 1 , R 2 , R 3 and R 4 are each independently an alkyl group or a hydroxyalkyl group, provided that at least one of R 1 , R 2 , R 3 and R 4 is an alkyl or hydroxyalkyl group having at least 3 carbon atoms, (b) a water-soluble amine, (c) water, (d) a corrosion inhibitor and (e) a water-soluble organic solvent, the compounding ratio of component (a) to component (b) being in the range of from 1:3 to 1:10 by mass.
• the present invention also provides a method of stripping photoresists which comprises forming a photoresist pattern on a substrate, etching the substrate using the photoresist as a mask, and thereafter stripping away the photoresist pattern from the substrate using the photoresist stripping solution as described above.
• the present invention furthermore provides a method of stripping photoresists which comprises forming a photoresist pattern on a substrate, etching the substrate using the photoresist as a mask, then plasma ashing the photoresist pattern, and thereafter stripping away post-plasma ashing residues from the substrate using the photoresist stripping solution as described above.
• component (a) is a quaternary ammonium hydroxide of the following general formula (I):
• R 1 , R 2 , R 3 and R 4 are each independently an alkyl group or a hydroxyalkyl group, provided that at least one of R 1 , R 2 , R 3 and R 4 is an alkyl or hydroxyalkyl group having at least 3 carbon atoms.
• the quaternary ammonium hydroxide represented by the general formula (I) is preferably at least one compound selected from among tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, methyltributylammonium hydroxide and methyltripropylammonium hydroxide.
• component (a) in the present invention is not only high in its ability to remove Si-based residues but also mild in its action of attacking Al, Cu, Si, etc.
• component (a) efficient stripping of Si-based residues and effective protection of not only the Si substrate but also wiring metals such as Al and Cu against corrosion can be achieved in a balanced way, thus providing a more desirable photoresist stripping solution.
• Compounds as component (a) can be used either singly or in admixture.
• the stripping solution of the invention preferably contains component (a) in an amount of 1-20 mass percent, more preferably 2-10 mass percent. If the proportion of component (a) is less than 1 mass percent, the overall stripping ability tends to be insufficient; if the proportion of component (a) is more than 20 mass percent, the substrate is prone to corrode.
• Water-soluble amine as component (b) include alkanolamines, such as monoethanolamine, diethanolamine, triethanolamine, 2-(2-aminoethoxy)ethanol, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine, monoisopropanolamine, diisopropanolamine and triisopropanolamine; polyalkylenepolyamines, such as diethylenetriamine, triethylenetetramine, propylenediamine, N,N-diethylethylenediamine, 1,4-butanediamine, N-ethyl-ethylenediamine, 1,2-propanediamine, 1,3-propanediamine and 1,6-hexanediamine; aliphatic amines, such as 2-ethyl-hexylamine, dioctylamine, dio
• Component (b) is compounded in a mass 3-10 times, preferably 4-9 times, the mass of component (a). If component (b) is compounded in a mass less than 3 times the mass of component (a), the overall stripping ability is inadequate; if component (b) is compounded in a mass more than 10 times the mass of component (a), the substrate is not adequately protected against corroding.
• Compounds used as component (b) have different strengths of attack on metals (e.g. Al and Cu) and Si, so it is recommended that they be compounded in a suitably adjusted optimum amount.
• metals e.g. Al and Cu
• Si metals
• Water as component (c) is incidental to the other components in the stripping solution of the invention but more of it need be added to have its amount adjusted to meet the purposes of the invention.
• Component (c) is preferably compounded in an amount of 10-50 mass percent, more preferably 20-45 mass percent, of the stripping solution of the invention. If the compounding amount of component (c) is less than 10 mass percent, the strippability of residues tends to decrease; if the compounding amount of component (c) exceeds 50 mass percent, the possibility for wiring metals such as Al and Cu to corrode is high.
• the compounding amount of component (c) is preferably optimized according to the device forming process. Take, for example, the stripping step which is currently performed by any one of dip method, spray method or paddle method. In a process adopting the dip or spray method which features a comparatively long time of contact between the photoresist stripping solution and the substrate, component (c) is preferably compounded in an amount of about 10-30 mass percent. In a process adopting the paddle method which features a comparatively short time of contact between the photoresist stripping solution and the substrate, component (c) is preferably compounded in an amount of about 30-50 mass percent.
• the corrosion inhibitor as component (d) is preferably at least one compound selected from among aromatic hydroxy compounds, benzotriazole-based compounds and mercapto group containing compounds.
• pyrocatechol, pyrogallol and gallic acid, etc. are used with advantage.
• the aromatic hydroxyl compounds may be used either individually or in combination.
• the benzotriazole-based compounds include the ones represented by the following general formula (II):
• R 5 and R 6 are each independently a hydrogen atom, a substituted or unsubstituted hydrocarbon group of 1-10 carbon atoms, a carboxyl group, an amino group, a hydroxyl group, a cyano group, a formyl group, a sulfonylalkyl group or a sulfo group;
• Q is a hydrogen atom, a hydroxyl group or a substituted or unsubstituted hydrocarbon group of 1-10 carbon atoms provided that said hydrocarbon group may have an amide bond or ester bond in the structure, an aryl group or the group represented by the following formula (III):
• R 7 represents an alkyl group of 1-6 carbon atoms
• R 8 and R 9 are each independently a hydrogen atom, a hydroxyl group or a hydroxyalkyl group or an alkoxyalkyl group of 1-6 carbon atoms.
• each of the hydrocarbon groups may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group, may be saturated or unsaturated, and may be a linear group or a branched group.
• Examples of a substituted hydrocarbon group include hydroxyalkyl groups and alkoxylalkyl groups.
• Q in the above general formula (II) is a group represented by the formula (III).
• R 8 and R 9 are independently a hydroxyalkyl group or an alkoxyalkyl group of 1-6 carbon atoms.
• Q preferably forms a water-soluble group and to give specific examples, a hydrogen atom, an alkyl group of 1-3 carbon atoms (i.e., methyl, ethyl, propyl or isopropyl), a hydroxyalkyl group of 1-3 carbon atoms and a hydroxyl group are particularly preferred from the viewpoint of effective protection of inorganic material layer, such as a polysilicon film, an amorphous silicon film, etc. against corrosion.
• benzotriazole-based compounds include benzotriazole, 5,6-dimethylbenzotriazole, 1-hydroxybenzotriazole, 1-methylbenzotriazole, 1-aminobenzotriazole, 1-phenylbenzotriazole, 1-hydroxymethylbenzotriazole, 1-benzotriazole-methyl carboxylate, 5-benzotriazole-carboxylic acid, 1-methoxybenzotriazole, 1-(2,2-dihydroxyethyl)benzotriazole, 1-(2,3-dihydroxypropyl)benzotriazole, and products of “IRGAMET” series marketed from Ciba Speciality Chemicals such as 2,2′- ⁇ [(4-methyl-1H-benzotriazol-1-yl)methyl]imino ⁇ bisethanol, 2,2′- ⁇ [(5-methyl-1H-benzotriazol-1-yl)methyl]imino ⁇ bisethanol, 2,2′- ⁇ [(4-methyl-1H-benzotriazol-1
• 1-(2,3-dihydroxypropyl)benzotriazole 2,2′- ⁇ [(4-methyl-1H-benzotriazol-1-yl)methyl]imino ⁇ bisethanol, 2,2′- ⁇ [(5-methyl-1H-benzotriazol-1-yl)methyl]imino ⁇ bisethanol, etc.
• the benzotriazole compounds may be used either individually or in combination.
• the mercapto group containing compound is preferably of such a structure that a hydroxyl group and/or a carboxyl group is present in either ⁇ -position or ⁇ -position on the carbon atom binding to the mercapto group.
• preferred examples of such compound include 1-thioglycerol, 3-(2-aminophenylthio)-2-hydroxypropylmercaptan, 3-(2-hydroxyethylthio)-2-hydroxypropylmercaptan, 2-mercaptopropionic acid and 3-mercaptopropionic acid.
• 1-thioglycerol is used with particular preference.
• Mercapto group containing compounds may be used either singly or in admixture.
• Component (d) is preferably chosen as appropriate for the fabrication process, more specifically, for the applicable device.
• the following three examples of the fabrication process may be mentioned:
• a photoresist pattern is formed on a substrate having an Al metal layer and after etching the substrate with said pattern being used as a mask, ashing or other treatment is performed to strip away the photoresist pattern, thereby forming Al metal wiring;
• a multiple of Si-based interlevel layers such as low-dielectric films (e.g. SOG film) and insulation films (e.g. SiN layer and SiO 2 layer) are formed in superposition on a Cu layer carrying substrate, and after etching the low-dielectric films and insulation films with the photoresist pattern on the topmost layer being used as a mask, the photoresist pattern is stripped away by ashing or other treatment to form via holes connecting to the Cu layer on the substrate;
• low-dielectric films e.g. SOG film
• insulation films e.g. SiN layer and SiO 2 layer
• the residues to be stripped away are mostly Al-based ones and the metal wiring to be protected against corrosion is made of an Al (inclusive of Al alloy) conductor.
• the aromatic hydroxy compound is preferably used as component (d) particularly from the viewpoint of preventing the Al conductor from corrosion.
• the residues to be stripped are mostly Cu-based residues that form on the bottom of via holes and the wiring metals to be protected against corroding are also mostly Cu-based ones.
• the benzotriazole-based compound and the mercapto group containing compound are preferably used.
• the residues are mostly Si-based ones and the wiring metals to be protected against corroding are mostly Cu-based ones.
• the benzotriazole-based compound and the mercapto group containing compound are preferably used. From the viewpoint of efficient stripping of the Si-based residues, it is preferred to use the benzotriazole-based compound in combination with the mercapto group containing compound. Since the combination of the aromatic hydroxy compound, water and the amine is known to be capable of enhanced stripping of the Si-based residues, the aromatic hydroxy compound is also used with preference in case (3).
• component (d) If two or more of the three compounds mentioned above as component (d) are used in combination, they are each preferably compounded in an amount of about 0.5-10 mass percent, more preferably about 1-4 mass percent. If the amount of each compound is less than 0.5 mass percent, Al or Cu is prone to corrode. Even if the amount of each compound exceeds 10 mass percent, there is no commensurate increase in effectiveness.
• the upper limit for the total content of component (d) is preferably no more than about 15 mass percent.
• Water-soluble organic solvents as component (e) are not specifically restricted so long as it is miscible with water and other components employed in the invention.
• water-soluble organic solvents include sulfoxides, such as dimethyl sulfoxide; sulfones, such as dimethyl sulfone, diethyl sulfone, bis(2-hydroxyethyl)sulfone and tetramethylene sulfone; amides, such as N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, N-methylacetamide and N,N-diethylacetamide; lactams, such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone and N-hydroxyethyl-2-pyrrolidone; imidazolidinones, such as 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone and 1,3-diisoprop
• preferable ones are dimethyl sulfoxide, dimethylimidazolidinone, N-methyl-2-pyrrolidone and diethylene glycol monobutyl ether.
• Component (e) may be used either alone or in combination with one another.
• the amount of component (e) is balance of total amounts of other components in the photoresist stripping solution of the invention.
• the stripping solution of the invention may further contain, as an optional component, an acetylene alcohol/alkylene oxide adduct prepared by adding an alkylene oxide to an acetylene alcohol.
• R 10 is a hydrogen atom or a group represented by the following formula (V):
• R 11 , R 12 , R 13 and R 14 are each independently a hydrogen atom or an alkyl group having 1-6 carbon atoms.
• acetylene alcohols are commercially available under trade names of “Surfynol” and “Olfin” series (both are produced by Air Product and Chemicals Inc.). Of these commercial products, “Surfynol 104”, “Surfynol 82” or mixtures thereof are most preferred for the physical properties. Use can be also made of “Olfin B”, “Olfin P”, “Olfin Y” etc.
• alkylene oxide to be added to the acetylene alcohol as described above it is preferable to use ethylene oxide, propylene oxide or a mixture thereof.
• R 15 is a hydrogen atom or a group represented by the following formula (VII):
• R 16 , R 17 , R 18 and R 19 are each independently a hydrogen atom or an alkyl group having 1-6 carbon atoms; (n+m) is an integer of 1 to 30, which is the number of ethylene oxide molecules added. This number subtly affects the properties of the compound such as water solubility and surface tension.
• acetylene alcohol/alkylene oxide adducts per se are known as surfactants. These products are commercially available under the trade names of “Surfynol” series (products of Air Product and Chemicals Inc.) and “Acetylenol” series (products of Kawaken Fine Chemicals Co., Ltd.) and have been appropriately utilized.
• a mixture of “Acetylenol EL” with “Acetylenol EH” in a mass ratio of 2:8 to 4:6 is particularly desirable.
• the stripping solution according to the invention contains the acetylene alcohol/alkylene oxide adduct, the amount thereof is preferably 0.05-5 mass percent, more preferably 0.1-2 mass percent.
• the content exceeds the upper limit as defined above, it tends to cause foaming but the wetting properties cannot be improved any more.
• the content is less than the lower limit as defined above, on the other hand, the desired improvement in the wetting properties can be scarcely established.
• the photoresist stripping solution of the invention can advantageously be used with all photoresists, whether negative- or positive-working, that can be developed with aqueous alkaline solutions.
• photoresists include, but are not limited to, (i) a positive-working photoresist containing a naphthoquinonediazide compound and a novolak resin, (ii) a positive-working photoresist containing a compound that generates an acid upon exposure, a compound that decomposes with an acid to have a higher solubility in aqueous alkali solutions, and an alkali-soluble resin, (iii) a positive-working photoresist containing a compound that generates an acid upon exposure and an alkali-soluble resin having a group that decomposes with an acid to have a higher solubility in aqueous alkali solutions, and (iv) a negative-working photoresist containing a compound that generates an acid upon illumination with
• photoresists are stripped away by one of two methods which have the following steps in common: forming a photoresist pattern by lithography on a substrate having conductive metallic layers, insulation layers and low-dielectric layers thereon, and selectively etching the layers with the photoresist pattern used as a mask to form a fine-line circuit. After these steps, the photoresist pattern is immediately stripped away (method I), or the etched photoresist pattern is subjected to plasma ashing and thereby post-ashing residues, such as the modified photoresist film (photoresist film residue) and metal deposition, are stripped away (method II).
• An example of method I in which the photoresist film is stripped away immediately after etching comprises:
• An example of method II in which the modified photoresist film and metal deposition resulting from plasma ashing are stripped away after etching comprises:
• the metal wiring can typically be aluminum (Al) based wiring or copper (Cu) based wiring.
• the Cu wiring as used in the invention may be either Cu alloy wiring that is mainly composed of Cu (in an amount of, say, at least about 90 mass percent) and which contains Al and other metals, or pure Cu wiring.
• any conventional means may be employed without particular limitation.
• post-exposure bake which is usually applied to the chemically amplified photoresist may be performed. Post bake may also be performed after forming the photoresist pattern.
• the photoresist is usually stripped by the dip, shower or paddle method.
• the stripping time is not limited to any duration as long as it is sufficient to achieve removal of the photoresist.
• the dual damascene process may be mentioned as a preferred mode of using the photoresist stripping solution of the invention. Specifically, the method described above in the column “2. Description of the Related Art” may be mentioned as a preferred example of the dual damascene process but needless to say, that is not the sole example of the dual damascene process that can be adopted.
• a silicon wafer having an SiO 2 layer formed thereon was used as a substrate (Si substrate).
• a substrate Si substrate
• an Al—Si—Cu layer, a TiN film and a P-TEOS film SiO 2 film deposited using tetraethyl orthosilicate
• the topmost layer was spin-coated with a positive working photoresist (TDUR-P015 of Tokyo Ohka Kogyo Co., Ltd.), which was prebaked at 90° C. for 90 seconds to form a photoresist layer 0.7 ⁇ m thick.
• TDUR-P015 positive working photoresist
• the photoresist layer was exposed through a mask pattern using FPA 3000 EX3 (Canon Inc.), then subjected to post-exposure bake at 110° C. for 90 seconds and developed with an aqueous solution of 2.38 mass percent tetraammonium hydroxide (TMAH) to form a pattern of holes 350 nm in diameter. Subsequently, post bake was performed at 110° C. for 90 seconds, followed by dry etching and ashing.
• TMAH tetraammonium hydroxide
• the thus processed substrate was subjected to strip away post-ashing residues with one of the photoresist stripping solutions (see Tables 1 and 2) by either dipping (70° C. ⁇ 30 min) or paddling (70° C. ⁇ 2 min) (see Table 3 for the specific treatment adopted) and subsequently rinsed with pure water.
• the strippability of the Si-based residue formed around the opening of each hole, the state of corrosion of the Al wiring at the bottom of each hole, and the state of corrosion of Si in the reverse surface of the Si substrate were evaluated by examination with an SEM (scanning electron microscope). The results are shown in Table 3.
• TBAH tetrabutylammonium hydroxide
• TPAH tetrapropylammonium hydroxide
• MTPAH methyltripropylammonium hydroxide
• MTBAH methyltributylammonium hydroxide
• TMAH tetramethylammonium hydroxide
• TEAH tetraethylammonium hydroxide
• CO choline
• MTEAH methyltriethylammonium hydroxide
• DMDEAH dimethyldiethylammonium hydroxide
• NMP N-methyl-2-pyrrolidone
• DEGE diethylene glycol monoethyl ether
• a a a 70° C.-2 min (paddling) Ex. 10 A a a 70° C.-2 min (paddling) Ex. 11 A a a 70° C.-2 min (paddling) Ex. 12 A a a 70° C.-30 min (dipping) Com.
• a b b 70° C.-30 min (dipping) Ex. 3 Com.
• Processed substrates were prepared by repeating the procedure employed in Examples 1-12.
• TPAH tetrapropylammonium hydroxide
• MEA monoethanolamine
• NMP N-methyl-2-pyrrolidone
• a silicon wafer having a SiO 2 layer formed thereon was used as a substrate (Si substrate).
• a Cu layer was formed in a thickness of 0.5 ⁇ m.
• the thus processed substrate II was stripped away of the post-ashing residues under the same conditions as for the substrate I and then rinsed with pure water.
• the state of corrosion of the Cu layer was evaluated by examination with an SEM (scanning electron microscope). The results are shown in Table 5.
• a photoresist stripping solution that is suitable for use in the photolithographic technology to form today's semiconductor and liquid-crystal display devices having an ever decreasing feature size and an increasing number of interlevel films superposed on the substrate and which can assure effective protection of Al, Cu and other wiring metal conductors against corrosion as well as efficient stripping of the photoresist film, post-ashing residues, and there is also provided a photoresist stripping solution that is particularly suitable for use in the formation of metal wiring on a substrate overlaid with Si-based interlevel films such as insulation films (e.g. SiO 2 film) and low-dielectric films (e.g. SOG film) and by means of which efficient stripping of Si deposition originating from these Si-based interlevel films and effective protection of the substrate (particularly the reverse side of an Si substrate) from corrosion can be accomplished in a balanced way.
• Si-based interlevel films such as insulation films (e.g. SiO 2 film) and low-dielectric films (e.g. SOG film)

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