WO2012161790A1

WO2012161790A1 - Concentrated chemical composition and method for removing photoresist during microelectric fabrication

Info

Publication number: WO2012161790A1
Application number: PCT/US2012/026480
Authority: WO
Inventors: John Moore
Original assignee: John Moore
Priority date: 2011-02-24
Filing date: 2012-02-24
Publication date: 2012-11-29

Abstract

The present invention is a concentrated chemical composition to remove photoresist during microelectronic fabrication that includes one or more active species which exhibit acidic or alkaline chemical properties that affects the photoresist removal performance, one or more inhibitor or protecting agents to an underlying substrate or one or more metal features to protect the substrate and one or more surface active agents providing sufficient wetting of the substrate without producing a foam level which prohibits sufficient tool performance. The concentrated chemical composition also includes one or more solvents and one or more carrier solvents to keep the formed chemical composition in a liquid form.

Description

CONCENTRATED CHEMICAL COMPOSITION AND METHOD FOR REMOVING

PHOTORESIST DURING MICROELECTRIC FABRICATION

This application claims priority to U.S. Provisional Application 61 /446,210 filed on 02/24/201 1 , the entire disclosure of which is incorporated by reference.

TECHNICAL FIELD & BACKGROUND

Ready-to-use chemicals cannot be changed fundamentally by one or more carrier solvents or a concentration of one or more chemical additives (concentrate chemistry). Furthermore, once the ready-to-use relatively low concentration chemical additive is expired, it is typically replaced as waste.

Chemical compositions based upon a liquid concentrate have several

advantages when used in the manufacturing of microelectronics that include an ability to choose a carrier solvent by which the liquid concentrate is to be diluted with an amount of the concentrate to blend with the carrier solvent (i.e. mixing ratio) to achieve a specific performance and/or a specific selectivity (i.e. corrosion resistance). The utilization of the mixtures and carrier solvents in a specific process flow are defined by the number and order of steps to achieve both desirable performance and selectivity. The liquid concentrate, when initially diluted and mixed into a carrier solvent, may be used, for example, as a photoresist stripper, and during its use, additional liquid concentrate may be added to replenish the performance of the initial mixture, resulting in an extension of the working life of the original mixture and a reduction in cost. The present invention generally relates to a chemical composition and method for removing photoresist during microelectronics fabrication. More specifically, the invention is a relatively highly concentrated chemical composition and method for removing photoresist during microelectronics fabrication of microelectronics devices and components.

It is an object of the invention to provide a relatively highly concentrated chemical composition and method for removing photoresist during microelectronic fabrication that reduces or eliminates a usage of one or more organic solvents, reduces costs, increases throughput and offers flexibility to manufacturing engineers and operators.

It is also an object of the invention to provide a relatively highly concentrated chemical composition and method for removing photoresist during microelectronics fabrication that may be replenished to its original relatively highly concentrated chemical composition as the process moves forward, providing a fundamental benefit to an engineering production staff.

It is also an object of the invention to provide a relatively highly concentrated chemical composition and method for removing photoresist during microelectronics fabrication that allows relatively more flexibility to mix on-site a plurality of chemicals required to remove and clean photoresist from one or more electronic substrates to increase a working life and process and dilute the relatively highly concentrated chemical composition in water to allow reduction or elimination of one or more organic solvents. What is really needed is a relatively highly concentrated chemical composition and method for removing photoresist during microelectronics fabrication that reduces or eliminates a usage of one or more organic solvents, reduces costs, increases throughput and offers flexibility to manufacturing engineers and operators that may be replenished to their original relatively highly concentrated chemical composition as the process moves forward, providing a fundamental benefit to an engineering staff that allows relatively more flexibility to mix on-site a plurality of chemicals required to remove and clean photoresist from one or more electronic substrates that replenish to increase a working life and process and dilute the relatively highly concentrated chemical composition in water to allow reduction or elimination of one or more organic solvents.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Various aspects of the illustrative embodiments will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments.

Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention. However, the order of description should not be construed as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

The phrase in one embodiment is utilized repeatedly. The phrase generally does not refer to the same embodiment, however, it may. The terms comprising, having and including are synonymous, unless the context dictates otherwise.

The chemical composition and method is utilized as a plurality of relatively concentrated chemicals to dissolve and remove photoresist from one or more microelectronic devices or materials. The chemical composition provides flexibility to a microelectronics device or material manufacturing facility by providing one or more carrier solvents, such as a suitable organic solvent or water that adjusts or customizes the chemical composition to clean the manufactured product by mixing the chemical composition at a variety of mixing ratios with the one or more carrier solvents and providing an increased working life by replenishment of an original chemical

composition being previously used with the relatively higher concentrated chemical composition.

The concentrated mixture of chemicals is in the approximate range of 10-100 times the traditional concentration of the active species of the chemical composition to conduct one or more specific photoresist or residue cleans. The active species is combined with an inhibitor, a surfactant and a carrier solvent to keep the formed chemical composition and added chemicals in a liquid form. The carrier solvent is chosen based on performance and selectivity in the resist removal process. The carrier solvent may contain a variety of one or more organic solvents or water. Once the concentrated mixture is mixed with the carrier solvent, the formed material is maintained at a specific temperature and brought into direct contact with a substrate to be cleaned during a suitable period of time to remove the photoresist and is followed with a dip in water or DIW rinse. Over time, replenishment may be necessary by addition of more concentrated chemical composition. This replenishment effectively maintains the concentration of the active species within the resist removing medium which increases the working life of the photoresist stripper. As a result of the use of the relatively higher concentration active species, increased flexibility is offered to a manufacturing facility with one or more choices in carrier solvents existing and one or more choices in mix ratio to adjust the mixture to the needs of the product and tool and replenishment of the chemical composition to provide an increase in the product bath life.

The concentrated chemical composition to remove photoresist during

microelectronics fabrication is based upon a plurality of relatively higher concentrated chemicals that have several advantages when used in the manufacturing of

microelectronics, including an ability to choose a carrier solvent by which the

concentrated chemical composition is to be diluted within, mixing a suitable quantity of the concentrate to blend with the carrier solvent (e.g. mixing ratio) to achieve a specific performance and/or a specific selectivity (i.e. corrosion resistance) and configuring the mixtures and carrier solvents in a specific process flow defined by the number and order of steps to achieve a relatively high level of performance and selectivity.

The chemical composition includes one or more active species which exhibit acidic or alkaline chemical properties that affects the photoresist removal performance of the photoresist, one or more inhibitor or protecting agents to an underlying substrate or one or more metal features, one or more surface active agents providing sufficient wetting of the substrate without producing a foam level which prohibits sufficient tool performance and one or more solvents selected from the from the group consisting of an alcohol, an amide, an ester, an ether, a glycol ether ester, a glycol ether, a glycol, a ketone, a lactate, a sulfoxide or water. The chemicals that consist of the chemical composition are present at elevated concentrations and are in a liquid form and are considered as a liquid concentrates intended to be diluted in carrier solvents at one or more points of use. The chemical composition consists of an active species that is in the range of approximately 10 to 99 wt%, an inhibitor or protecting agent in the range of approximately 0.5 to 50.0 wt%, a surface active agent in the range of approximately 0.5 to 50 wt% and a solvent in the range of approximately 0.5 to 50 wt%. The chemical composition is mixed as a free-flowing liquid intended to be diluted with one or more carrier solvents for use as a photoresist stripper or remover.

More specifically the one or more alkali active species are selected from the group consisting of ammonium hydroxide, one or more quaternary hydroxides such as tetramethyl ammonium hydroxide (TMAH), tetraethyl ammonium hydroxide (TEAH), benzyltrimethyl ammonium hydroxide (BTMAH), one or more amines such as

triethylene tetramine, alkanolamine, monoethanolamine, monoisopropanolamine, diglycolamine, one or more elemental hydroxides or alkoxides such as potassium tertiary butyl hydroxide (KTB). The one or more acidic active species are selected from the group of one or more alkyl-sulfonic acids such as methanesulfonic (MSA), Toluenesulfonic (TSA), dodecylbenzene sulfonic acid (DDBSA), formic acid, one or more fatty acids, sulfuric acid, nitric acid, or phosphoric acid.

More specifically the one or more inhibitor or protecting agents are selected from the group consisting of one or more chelating agents, one or more complexing agents, or reducing agents such as benzylic hydroxide, catechol, triazole, imidazole, borate, one or more phosphates, and one or more alkyl or elemental silicates,

ethylenediaminetetraacetic acid, diethylenetnaminepentaacetic acid, nitrilotriacetic acid, 2,4-pentanedione, one or more reducing sugars, one or more hydroquinones, glyoxal, salicylaldehyde, one or more fatty acids such as citric and ascorbic acid, one or more hydroxylamines, or vanillin.

More specifically the one or more surface active agents are selected from the group consisting of one or more nonionic, anionic, and amphoteric acting species, fluorinated, one or more nonyl-phenols, one or more nonyl-ethoxylates with a HLB (hydrophilic/lipophilic balance) ranging from 7-15, one or more alkyl-sulfonates, one or more phosphate esters, and one or more succinates.

More specifically the one or more solvents are selected from the group consisting of one or more ketones such as cyclohexanone, 2-heptanone, methyl propyl ketone, and methyl amyl ketone, esters such as isopropyl acetate, ethyl acetate, butyl acetate, ethyl propionate, methyl propionate, gamma- butyrolactone (BLO), ethyl 2- hydroxypropionate (ethyl lactate (EL)), ethyl 2-hydroxy-2-methyl propionate, ethyl hydroxyacetate, ethyl 2-hydroxy-3-methyl butanoate, methyl 3-methoxypropionate, ethyl 3-methoxy propionate, ethyl 3-ethoxypropionate, methyl 3-ethoxy propionate, methyl pyruvate, and ethyl pyruvate, one or more ethers and glycol ethers such as diisopropyl ether, ethyleneglycol monomethyl ether, ethyleneglycol monoethyl ether, diethylene glycol monoethyl ether and propylene glycol monomethyl ether (PGME), one or more glycol ether esters such as ethyleneglycol monoethyl ether acetate, propyleneglycol methyl ether acetate (PGMEA), propyleneglycol propyl ether acetate, one or more aromatic solvents such as methylbenzene, dimethylbenzene, anisole, and nitrobenzene, one or more amide solvents such as Ν,Ν-dimethylacetamide (DMAC), N,N- dimethylformamide, and N-methylformanilide, and one or more pyrrolidones such as N- methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), dimethylpiperidone, 2-pyrrole, N- hydroxyethyl-2-pyrrolidone (HEP), N-cyclohexyl-2-pyrrolidone (CHP), one or more sulfur containing solvents such as dimethyl sulfoxide, dimethyl sulfone and tetramethylene sulfone, and 3-methoxy-3-methyl-1 -butanol (MMB) or water.

The method of using the concentrated chemical composition includes diluting the concentrated chemical composition with one or more into selected carrier solvents at the point of use. Dilution may occur within a staging area or within a manufacturing lab or other suitable location. The concentrated chemical composition is mixed to a desired level with one or more selected carrier solvents and then sent to the cleaning tool. The mixture may be utilized at room temperature (i.e. 20^°C). However, it is commonly heated to a predetermined temperature to achieve suitable photoresist removal performance and selectivity. Once operation begins, performance is measured by a time period allowed to completely remove the photoresist. Rinsing is conducted with DIW, typically using immersion or one or more spray methods as typically conducted by the fabrication tool operation. Options utilizing the concentrated chemical composition include a plurality of variable choices and mixture of one or more carrier solvents to be added to or mixed with one or more of the carrier solvents. Additional options include using the

concentrated chemical composition in different formulations, such as being diluted at approximately 10% in carrier solvent X then diluting approximately 5% in carrier solvent Y or other suitable dilution percentages. Once mixed and operated over time, replenishment with the concentrated chemical composition may be performed to increase bath life.

More specifically the one or more carrier solvents are selected from the group consisting of one or more esters with a structure R-CO₂Ri , one or more glycol ether esters structures, R₂-CO₂C₂H₄OC₂H₄-OR3, R₄-CO₂C₃H₆OC₃H₆-OR5 and R₆OCO₂R₇ , alcohols selected from structures R₈OH, R₉OC₂H₄OC₂H₄OH, R₁₀OC₃H₆OC₃H₆OH, RiiOC₂H₄OH, and R-i₂OC₃H₆OH, ketones selected from structures R-I₃COR-I_4i sulfoxides selected from structure R-I₅SOR-I₆, and one or more amides such as N,N-dimethyl formamide, Ν,Ν-dimethyl acetamide, N-methyl pyrolidone, wherein R, R _; R₂, R₃, R₄, R₅, R₆, R₇, Rs, R9, R-io, R-11 , R-12, R-13, R-I4, R-15, and R-|₆ are independently selected from Ci - Ci₄ - alkyl groups, while R, R-i , R-|₃, R-|₄ may be selected from Ci to C₈ alkyl groups. The carrier solvent may also include water for dilution.

The invention also comprises a method for stripping an organic substance from an inorganic substrate by bringing the composition into direct contact with the substrate, with or without heat, and for a sufficient time to dissolve the photoresist, and remove it by rinsing with water. The compositions and methods have particular applicability to semiconductor wafer fabrication, for example, in the removal of photoresist and residues from semiconductor wafers. Such organic substances are present, for example, on wafers during back-end wafer-level-packaging in a wafer bumping process. The compositions and methods are particularly suitable for the removal from of dry-film photoresist identified as hard-to-remove, or that material identified as resistant to conventional cleaners.

The terms "stripping", "removing", and "cleaning" are used interchangeably throughout this specification. Likewise, the terms "stripper", "remover", and "cleaning composition" are used interchangeably. The indefinite articles "a" and "an" are intended to include both the singular and the plural. All ranges are inclusive and combinable in any order except where it is clear that such numerical ranges are constrained to add up to 100%. The term "wt%" means weight percent based on the total weight of the stripping composition, unless otherwise indicated.

The present invention is to facilitate a rapid removal of photoresist without attacking (e.g. corrosion) to an underlying substrate, one or more metals, or one or more dielectrics. The substrates include silicon, silicon dioxide, gallium arsenide

(GaAs), glass, sapphire, quartz, and other suitable materials. Features on the substrate are typically composed of metal such as copper, aluminum, nickel, titanium, and other similar layers with one or more pads, contacts, leads, and solder alloys composed of tin, lead, silver, copper, and similar materials used for conduction. Other materials include dielectrics such as nitrides of silicon, polyimide, polybenzoxazole (PBO), silicone, bis- benzocyclobutene (BCB), and one or more related non-conducting films. The chemical composition and method teaches the ability to remove photoresist by a variety of means while achieving the desired selectivity needed to protect a wide variety of underlying materials.

Example #1 : Photoresist stripper and detergent concentrate

Item # Identity Appearance % (w/w)

1 Purified Water Liquid 35.65% 2 Potassium Hydroxide, Liquid 13.1 1 %

45% Solution

Lithium Hydroxide, Solid 1 .43%

Monohydrate

Kasil 1624 Potassium Liquid 44.78%

Silicate

Benzotriazole (BTA, Solid 0.23% Wintrol B-F)

Tolytriazole (TTA, Solid 0.15% Wintrol TF-P)

Resinall R-830 (Silicon Solid 1 .45% etching inhibitor)

Potassium Citrate Solid 1 .50% Tribasic Monohydrate

9 Hexamine Solid 1 .45%

10 Chemguard S-764P Gel 0.25%

(VOC-Free Phoshate

Ester Fluorosurfactant)

Totals 100.00% While the present invention has been related in terms of the foregoing embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described. The present invention can be practiced with modification and alteration within the spirit and scope of the appended claims. Thus, the description is to be regarded as illustrative instead of restrictive on the present invention.

Claims

1 . A concentrated chemical composition to remove photoresist during

microelectronic fabrication, consisting of:

one or more active species which exhibit acidic or alkaline chemical properties that affects said photoresist removal performance;

one or more inhibitor or protecting agents to an underlying substrate or one or more metal features to protect said substrate;

one or more surface active agents providing sufficient wetting of said substrate without producing a foam level which prohibits sufficient tool performance;

one or more solvents; and

one or more carrier solvents to keep said formed chemical composition in a liquid form.

2. The concentrated chemical composition according to claim 1 , wherein said the one or more alkali active species are selected from the group consisting of ammonium hydroxide, one or more quaternary hydroxides, tetramethyl ammonium hydroxide (TMAH), tetraethyl ammonium hydroxide (TEAH), benzyltrimethyl ammonium hydroxide (BTMAH), one or more amines, triethylene tetramine, alkanolamine,

monoethanolamine, monoisopropanolamine, diglycolamine, one or more elemental hydroxides or alkoxides, and potassium tertiary butyl hydroxide (KTB).

3. The concentrated chemical composition according to claim 1 , wherein said one or more acidic active species are selected from the group of one or more alkyl-sulfonic acids, methanesulfonic (MSA), Toluenesulfonic (TSA), dodecylbenzene sulfonic acid (DDBSA), formic acid, one or more fatty acids, sulfuric acid, nitric acid, and phosphoric acid.

4. The concentrated chemical composition according to claim 1 , wherein said one or more acidic and alkaline active species are in the range of approximately 10 to 99 wt%.

5. The concentrated chemical composition according to claim 1 , wherein said one or more inhibitor or protecting agents are selected from the group consisting of one or more chelating agents, one or more complexing agents, or reducing agents such as benzylic hydroxide, catechol, triazole, imidazole, borate, one or more phosphates, one or more alkyl or elemental silicates, ethylenediaminetetraacetic acid,

diethylenetriaminepentaacetic acid, nitrilotriacetic acid, 2,4-pentanedione, one or more reducing sugars, one or more hydroquinones, glyoxal, salicylaldehyde, one or more fatty acids, citric acid, ascorbic acid, one or more hydroxylamines, and vanillin.

6. The concentrated chemical composition according to claim 1 , wherein said inhibitor or protecting agent is in the range of approximately 0.5 to 50.0 wt%.

7. The concentrated chemical composition according to claim 1 , wherein said the one or more surface active agents are selected from the group consisting of one or more nonionic, anionic, and amphoteric acting species, fluorinated, one or more nonyl- phenols, one or more nonyl-ethoxylates with a hydrophilic and lipophilic balance ranging from 7-15, one or more alkyl-sulfonates, one or more phosphate esters, and one or more succinates.

8. The concentrated chemical composition according to claim 1 , wherein said one or more surface active agents provide sufficient wetting of said substrate without producing a foam level which prohibits sufficient tool performance.

9. The concentrated chemical composition according to claim 1 , wherein said surface active agent is in the range of approximately 0.5 to 50 wt%.

10. The concentrated chemical composition according to claim 1 , wherein said one or more solvents are selected from the group consisting of one or more ketones, cyclohexanone, 2-heptanone, methyl propyl ketone, methyl amyl ketone, one or more esters, isopropyl acetate, ethyl acetate, butyl acetate, ethyl propionate, methyl propionate, gamma-butyrolactone (BLO), ethyl 2-hydroxypropionate (ethyl lactate (EL)), ethyl 2-hydroxy-2-methyl propionate, ethyl hydroxyacetate, ethyl 2-hydroxy-3-methyl butanoate, methyl 3-methoxypropionate, ethyl 3-methoxy propionate, ethyl 3- ethoxypropionate, methyl 3-ethoxy propionate, methyl pyruvate, ethyl pyruvate, one or more ethers and glycol ethers, diisopropyl ether, ethyleneglycol monomethyl ether, ethyleneglycol monoethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether (PGME), one or more glycol ether esters, ethyleneglycol monoethyl ether acetate, propyleneglycol methyl ether acetate (PGM EA), propyleneglycol propyl ether acetate, one or more aromatic solvents, methylbenzene, dimethylbenzene, anisole, nitrobenzene, one or more amide solvents, Ν,Ν-dimethylacetamide (DMAC), Ν,Ν-dimethylformamide, and N-methylformanilide, one or more pyrrolidones, N- methylpyrrolidone (NM P), N-ethylpyrrolidone (N EP), dimethylpiperidone, 2-pyrrole, N- hydroxyethyl-2-pyrrolidone (H EP), N-cyclohexyl-2-pyrrolidone (CH P), one or more sulfur containing solvents, dimethyl sulfoxide, dimethyl sulfone, tetramethylene sulfone, 3- methoxy-3-methyl-1 -butanol (MMB) and water.

1 1 . The concentrated chemical composition according to claim 1 , wherein said solvent is in the range of approximately 0.5 to 50 wt%.

12. The concentrated chemical composition according to claim 1 , wherein said one or more carrier solvents are selected from the group consisting of one or more esters with a structure R-C0₂Ri , one or more glycol ether esters structures, R₂- C0₂C₂H₄OC₂H₄-OR3, R₄-C0₂C3H₆OC3H₆-OR₅ and R₆OC0₂R₇ , one or more alcohols selected from structures R₈OH, R₉OC₂H₄OC₂H₄OH, R₁₀OC₃H₆OC₃H₆OH, RnOC₂H₄OH, and R-i₂OC₃H₆OH, ketones selected from structures R-I₃COR-I_4i sulfoxides selected from structure R ₅SOR ₆, and one or more amides, Ν,Ν-dimethyl formamide, N,N-dimethyl acetamide, N-methyl pyrolidone, wherein R, R _; R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, R ₀, Rn , R-12, R-13, R-14, Ri 5, and Ri₆ are independently selected from Ci - C_M - alkyl groups, while R, R-i, Ri₃, Ri₄ may be selected from Ci to C₈ alkyl groups.

13. The concentrated chemical composition according to claim 1 , wherein said one or more carrier solvent adjusts or customizes said chemical composition to clean said photoresist by mixing said chemical composition at a variety of mixing ratios with said one or more carrier solvents.

14. The concentrated chemical composition according to claim 1 , wherein said one or more carrier solvent is brought into contact with said substrate or one or more metal features that is cleaned to remove said photoresist and is followed with a dip in water rinse.

15. The concentrated chemical composition according to claim 1 , wherein said one or more carrier solvents provide an increased working life by replenishment of an original chemical composition being previously used with said concentrated chemical composition.

16. The concentrated chemical composition according to claim 1 , wherein said one or more carrier solvents are chosen based on performance and selectivity in said photoresist removal.

17. The concentrated chemical composition according to claim 1 , wherein said concentrated chemical composition is in the approximate range of 10-100 times a traditional concentration of said active species of said chemical composition to conduct one or more specific said photoresist or residue cleans.

18. The concentrated chemical composition according to claim 16, wherein said chemical composition dissolves and removes said photoresist from one or more microelectronic devices or materials.

19. The concentrated chemical composition according to claim 1 , wherein said chemical composition is present at one or more elevated concentrations and are in a liquid form and are intended to be diluted in said carrier solvents at one or more points of use.

20. A concentrated chemical composition to serve as a photoresist stripper and detergent concentrate, consisting of:

approximately 35.65% purified water;

approximately 13.1 1 % of a 45% solution of potassium hydroxide;

approximately 1 .43% monohydrate lithium hydroxide;

approximately 44.78% potassium silicate;

approximately 0.23% benzotriazole;

approximately 0.15 % tolytriazole;

approximately 1 .45% silicon etching inhibitor; approximately 1 .50% potassium citrate tribasic monohydrate; approximately 1 .45% hexamine; and

approximately 0.25% VOC-free phosphate ester fluorosurfactant.