WO2015069776A1

WO2015069776A1 - Novel photo-resist stripper

Info

Publication number: WO2015069776A1
Application number: PCT/US2014/064142
Authority: WO
Inventors: Howard P. Klein; Zheng Chai
Original assignee: Huntsman Petrochemical Llc
Priority date: 2013-11-11
Filing date: 2014-11-05
Publication date: 2015-05-14
Also published as: TW201527284A

Abstract

New compounds, compositions, and methods for stripping photoresist materials are described. The compounds are substituted cycloureas and cyclocarbamates having at least one substituent that is a proton-accepting group. The proton-accepting group may be a hydroxyalkyi group or an aminoalkyi group. Such compounds may be blended with other solvents to make a composition useful for stripping photoresists. Methods for using such compositions include applying the compositions to a substrate surface as a liquid or as a vapor.

Description

NOVEL PHOTO-RESIST STRIPPER

FIELD

[0001] Embodiments described herein are generally related to semiconductor manufacturing. More specifically, a novel type of material for use in stripping photoresist materials is described.

BACKGROUND

[0002] The global semiconductor processing industry is a $300 billion per year industry that relies on precision processes for depositing and removing materials from a semiconductor substrate. At the core of this industry is the process of forming a pattern of nanoscopic devices on a semiconductor substrate. Typically, a first layer of material is formed on the substrate and then patterned by a chemical process. The patterning typically includes forming a patterning layer over the first layer, exposing the patterning layer to a pattern of radiation to change the material of the patterning layer in the irradiated areas. Then, a chemical developer is used to preferentially remove the irradiated or non- irradiated material.

[0003] The process is typically performed over the entire surface of a semiconductor wafer or panel according to a pattern established by the patterning layer. In many such processes, the patterning layer is a photoresist because the layer is made of a material that absorbs radiation and undergoes a change. The photoresist may define areas where etching is to be performed to remove material from the substrate, or the photoresist may define areas where material is to be deposited on the substrate. In any event, patterning the photoresist enables the substrate surface to be treated according to a pattern.

[0004] The material of the patterning layer that remains after development of the pattern may be used as a mask for a subsequent process that treats exposed areas of the substrate below the patterning layer. Processes that are commonly performed include material deposition, ion implantation, material removal, and thermal processing. After the mask process is complete, the mask material is commonly removed by a wet or dry stripping process featuring a reagent that removes the mask material, or photoresist. In some cases, however, the reagents typically used to remove photoresist may damage materials in the substrate surface. For example, metals in the substrate surface may react with photoresist stripping reagents, altering their electrical properties and compromising the function of the devices on the substrate. Thus, there is a need for new reagents for removing photoresists without damaging materials of the substrate.

[0005] A photoresist is typically a carbon-containing material, such as carbon polymers or amorphous carbon. Polymers commonly used include polymethylmethacrylate, polymethylglutarimide, and novolac resins, which are frequently applied by spin-coating and then heated to harden or dry the coating. The coating is exposed to radiation, typically UV radiation, through a mask so that the radiation falls on the coating according to a pattern formed in the mask. The radiation changes the structure of the coating in the irradiated areas so that a solvent or etchant preferentially removes either the irradiated or the non- irradiated material to leave the patterned photoresist. The photoresist is, itself, then typically used as a mask for deposition, ion implantation, and/or etching of the substrate surface beneath the photoresist.

[0006] After photoresist processing, the photoresist is typically removed. In many cases, the substrate may have metal features that can be damaged by conventional materials used to remove photoresists. Thus, there is a need in the art for a photoresist stripping composition and process that does not damage substrates. SUMMARY

[0007] This application describes new compounds, compositions, and methods for stripping photoresist materials. The compounds are substituted cyclic ureas and cyclic carbamates having at least one substituent that is a proton-accepting group. The proton-accepting group may be a hydroxyalkyl group or an aminoalkyl group. Such compounds may be blended with other solvents to make a composition useful for stripping photoresists. Methods for using such compositions include applying the compositions to a substrate surface as a liquid or as a vapor.

DETAILED DESCRIPTION

[0008] The inventors have discovered new types of reagents that can be used to remove mask materials typically used in semiconductor processing with minimal or no damage to materials that may be present in devices on the substrate from which the photoresist is removed. The reagents are substituted cycloureas and cyclocarbamates. The substitutions may be made at one or more carbon atoms in the ring or at one or more nitrogen atoms in the ring. Typically, at least one of the substituents is a group having an affinity for protons in an aqueous environment, making the reagents, or compositions containing the reagents, basic to varying degrees. The basic substituents may be alcohol groups or amino groups, which may be linear, branched, or cyclic, and may be primary, secondary, or tertiary groups. The other substituents may be any desired substituents, such as hydrocarbyl groups, hydrocarbenyl groups, hetero- organic groups such as oxygen and/or nitrogen containing groups, aryl groups, or hydrogen.

[0009] A proton-accepting group may be bonded to a nitrogen atom in the cyclic ring of the reagent. Alternately, a proton-accepting group may be bonded to a carbon atom in the cyclic ring of the reagent. In one embodiment, two proton-accepting groups may be bonded to the ring. Both groups may be bonded to carbon atoms, both may be bonded to nitrogen atoms, or one may be bonded to a carbon atom and one to a nitrogen atom. A hydroxyalkyl group and/or an aminoalkyi group may be bonded to the ring of the cyclourea or the cyclocarbamate.

[0010] The cycloureas and cyclocarbamates have a general structure, as follows:

Structure A Structure B

In each of the formulas above, n is 1 to 4, for example 1 or 2. In each of the formulas above, at least one of R¹-R⁶ is a proton-accepting group. The proton- accepting group may be an alcohol group, such as a hydroxyalkyl group, or an amine group, such as an aminoalkyi group. Amine groups may be primary, secondary, or tertiary amine groups. R¹ and R⁶ may bonded to nitrogen at a carbon atom, an oxygen atom, or a nitrogen atom. More than one of R¹-R⁶ may be proton-accepting groups. Two, three, four, five, or all six of R¹-R⁶ may be proton-accepting groups. So long as at least one of R¹-R⁶ is a proton accepting group, each of the other groups may individually be hydrogen, a hydrocarbon group such as alkyl, alkenyl, cycloalkyi, cycloalkenyl, or aryl, for example a methyl group, an oxygen containing group, a nitrogen containing group, or another functional group. Typically, when R², R³, R⁴, and R⁵ are each H, then R¹ and R⁶ are different in the cyclourea.

[0011] Embodiments of the cycloureas described above as Structure B may be made by reacting urea H₂NCONH₂ with a diamine. A straight-chain unsubstituted diamine of general formula H₂ (CH2)_mNH2, reacted with urea, typically produces a cyclourea of general formula HNCONH-(CH₂)_m-- Use of a generalized C-substituted diamine H₂N[(CH₂)a(CHi_-xRx)_b(CH₂)c]qH₂N gives a cyclourea of general formula HNCONH-[(CH2)a(CH_1-xRx)b(CH2)c]q-, where R can be any of the substituent groups described above for R¹-R⁶. Thus, the following reaction is expected to give some embodiments of Structure B:

[0012] Diamines may also be reacted with alkylene carbonates to produce embodiments of Structure B, as follows:

N-alkyl substituted diamines RHN(CH₂)_mNHR', when reacted with urea, generally produce N-alkyl substituted cycloureas RNCONR'-(CH2)_m-- N- hydroxyalkyl substituted cycloureas may be made by first making a cyclourea, which may be substituted at any carbon atom thereof, and then reacting the cyclourea with an alkylene oxide. A distribution of mono- and di-substituted N- hydroxylalkyl cycloureas results, which can be controlled to some extent by stoichiometry. N-aminoalkyl cycloureas may also be made by reacting dialkylene carbonates with triamines, as follows:

[0013] Embodiments of the cyclocarbamates described above as Structure A may be made by reacting an alkanolamine with phosgene. As above, carbon and nitrogen substituents of the alkanolamine typically remain in the cyclocarbamate, and substituents may be added to the nitrogen atom of the cyclocarbamate as above. Thus, a straight-chain alkanolamine of formula HO(CH₂)_mNH₂ reacts with phosgene to form the cyclocarbamate of general formula HNCOO-(CH₂)_m-, the generalized C-substituted alkanolamine HO[(CH₂)a(CH_1-xR_x) (CH2)_c]_qH2N reacts with phosgene to give a cyclocarbamate of general formula HNCOO-[(CH₂)a(CH_1-xRx)b(CH2)c]q-, where R can be any of the substituent groups described above for R¹-R⁶, and N-alkyl substituted alkanolamines RHN(CH₂)_mOH, when reacted with phosgene, generally produce N-alkyl substituted cyclocarbamates RNCOO'-(CH₂)_m-. Thus, the following reaction is expected to give some embodiments of Structure A:

[0014] Substituting for one hydrogen atom of the alkanolamine typically yields an N-substituted cyclocarbamate. So, use of the alkanolamine analog of the triamine above will usually result in an N-substituted cyclocarbamateproducts, as shown below, depending on the distribution of reactivities with nitrogen and oxygen bound hydrogens:

[0015] Examples of reagents found to be useful as photoresist stripping agents are as follows:

[0016] Reagents useful as photoresist stripping agents include, but are limited to, Ν,Ν-dyhydroxyethylcyclourea, N,N-diaminoethylcyclourea, hydroxyethylcyclocarbamate, N-aminoethylcyclocarbamate, diethylaminoethylcyclourea, N-diethylaminoethylcyclocarbamate, N- ethylaminoethylcyclourea, N-ethylaminoethylcyclocarbamate,

[0017] The reagents described above may be used in compositions that may be applied to substrates in liquid and/or vapor form to remove photoresist materials. One or more of the reagents described above may be blended with a solvent in an aqueous environment to form a stripping composition. Solvents that may be used include water, dimethylsulfoxide (DMSO), acetonitrile (ACN), dimethylformamide (DMF), dimethylacetamide (DMA), and tetrahydrofuran (THF). Such compositions may include one or more reagents of the type described above. Such compositions may also include photoresist stripping agents currently in common use, such as N-methylpyrrolidone and 3-methyl-2- oxazolidinone.

[0018] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

Claims:

1. A compound having the general formula

or the general formula

where n is 1 to 2, each of R¹-R⁶ is, independently, H, a hydrocarbyl group, a hydrocarbenyl group, a hetero-organic substituent, a proton-accepting group, an aryl group, at least one of R¹-R⁶ is a proton-accepting group, and if R¹ or R⁶ is a hydroxyalkyi group, then at least one of R¹ and R⁶ has more than one carbon atom.

2. The compound of claim 1 , wherein every proton-accepting group is a hydroxyalkyi group or an aminoalkyl group.

3. The compound of claim 1 or 2, further comprising a substituent that is not a proton-accepting group.

4. The compound of claim 1 , wherein the compound is a cyclourea and one nitrogen atom in the ring of the cyclourea is unsubstituted.

5. The compound of claim 1 or 2, wherein every proton-accepting group is bonded to a carbon atom.

6. A composition comprising the compound of claim 1 and an aqueous solvent.

7. A composition comprising the compound of claim 1 and a solvent selected from the group consisting of DMSO, DMF, THF, and ACN.

8. The composition of claim 6 or 7 further comprising a second photoresist stripping reagent.

9. A photoresist stripping composition, comprising:

a reagent having the general formula

or the general formula

where n is 1 to 2, each of R -R⁶ is, independently, H, a hydrocarbyl group, a hydrocarbenyl group, a hetero-organic substituent, a proton-accepting group, an aryl group, at least one of R¹-R⁶ is a proton-accepting group, and if R¹ or R⁶ is a hydroxyalkyl group, then at least one of R¹ and R⁶ has more than one carbon atom;

a solvent selected from the group consisting of DMSO, DMF, THF, and ACN; and

an aqueous component.

10. The photoresist stripping composition of claim 9, wherein every proton- accepting group is a hydroxyalkyl group or an aminoalkyl group. 1. The photoresist stripping composition of claim 9 or 10, wherein the reagent further comprises a substituent that is not a proton-accepting group.

12. The photoresist stripping composition of claim 9 or 10, further comprising a photoresist stripping agent.

13. A method of removing a photoresist material from a substrate, comprising: exposing the substrate to a composition comprising a reagent having the general formula

or the general formula

where n is 1 to 2, each of R -R⁶ is, independently, H, a hydrocarbyl group, a hydrocarbenyl group, a hetero-organic substituent, a proton-accepting group, an aryl group, at least one of R¹-R⁶ is a proton-accepting group, and if R or R⁶ is a hydroxyalkyl group, then at least one of R and R⁶ has more than one carbon atom.

14. The method of claim 13, wherein the composition is a liquid.

15. The method of claim 13 or 14, wherein the composition further comprises an aqueous component.

16. The method of claim 13 or 14, wherein the composition further comprises a solvent selected from the group consisting of DMSO, DMF, THF, and CAN.

17. The method of claim 13, wherein every proton-accepting group is a hydroxyalkyl group or an aminoalkyl group.

18. The method of claim 17, wherein the reagent further comprises a substituent that is not a proton-accepting group.

19. The method of claim 18, wherein the composition is basic.