| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 28.11.2000 |
| PATENT TITLE |
Process for forming carbonates of hydroxyaromatic compounds |
| PATENT ABSTRACT | A process for the stoichiometric carbonation of a hydroxyaromatic material is provided which comprises the steps of (a) mixing together in a reaction vessel (1) a hydroxyaromatic material, (2) a sufficient amount of a dialkyl dicarbonate to give the desired degree of substitution, (3) a catalytic amount of an unhindered tertiary amine, and (4) a solvent, (b) stirring the reaction mixture, (c) precipitating the alkyl carbonate of the hydroxyaromatic material, and (d) recovering the alkyl carbonate of the hydroxyaromatic material. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | May 10, 1993 |
| PATENT REFERENCES CITED |
H. Ito; Solid State Thermolysis of BTBOC Catalyzed by Phenol; Jrnl Polymer Science, Polymer Chemistry; vol. 24, (1986), pp. 2971-2980. F. Houlihan, et al. "Phase Transfer Catalysis in the tert-Butyloxycarbonylation of Alcohols, Phenols, Enols, and Thiols with di-tert-Butyl Dicarbonate", Can. J. Chem., 63, 153 (1985). |
| PATENT CLAIMS |
We claim: 1. A process for the stoichiometric carbonation of a microlithographically useful polymer comprising hydroxyaromatic groups comprising the steps of (a) mixing together in a reaction vessel (1) a hydroxyaromatic material, (2) a stoichiometric amount of a dialkyl dicarbonate to give the desired degree of substitution, (3) a catalytic amount of an unhindered tertiary amine, wherein the amine is selected from the group consisting of amines comprising substituted and unsubstituted heterocyclic compounds, diethylmethyl amine, trimethyl amine, and polymers having unhindered amino groups, and (4) a solvent with the proviso that the reaction mixture does not contain an organic amine base in an amount exceeding 0.02 molar equivalents based on the dialkyl dicarbonate, and (b) stirring the reaction mixture, (c) precipitating the alkyl carbonate of the hydroxyaromatic material, and (d) recovering the alkyl carbonate of the polymeric hydroxyaromatic material. 2. The process of claim 1 where the tertiary amine is present in the range from about 0.001 to 0.02 molar equivalents based on the dialkyl dicarbonate. 3. The process of claim 1 wherein the hydroxy aromatic material is selected from the group consisting of phenolic polymers and monomeric phenols. 4. The process of claim 3 wherein the phenolic polymers comprise poly(hydroxystyrenes) and novolak resins. 5. The process of claim 3 wherein the monomeric phenols comprise Bisphenol A and tris(hydroxphenyl)ethane. 6. The process of claim 1 wherein the dialkyl dicarbonate is selected from the group consisting of primary, secondary and tertiary dialkyl dicarbonates. 7. The process of claim 6 wherein the tertiary dialkyl dicarbonates comprises di-tert-butyl dicarbonate and di-(t-amyl)dicarbonate. 8. The process of claim 6 wherein the primary dialkyl dicarbonate comprises diethyl dicarbonate. 9. The process of claim 1 wherein the unhindered tertiary amine comprises 2-dimethylaminopyridine, 4-dimethylaminopyridine, 4-pyrrolidino-pyridine, diethylmethylamine, trimethylamine, N-methylpyrrolidine, and polymers having unhindered amino groups. 10. A process for preparing a microlithographically useful, stoichiometrically derivatized poly(p-hydroxystyrene) having a degree of substitution of from 10-100% comprising the steps of (a) mixing together in a reaction vessel at ambient temperature (1) poly(p-hydroxystyrene), (2) a stoichiometric amount of di-tert-butyl dicarbonate to give the desired degree of substitution, and (3) a catalytic amount of a dimethylaminopyridine in a solvent for the reactants, with the proviso that the reaction mixture does not contain an organic amine base in an amount exceeding 0.02 molar equivalents based on the di-tert-butyl dicarbonate, and (b) stirring the reaction mixture, (c) precipitating the t-butyloxycarbonyl O-substituted poly(p-hydroxystyrene), and (d) recovering the precipitated t-butyloxycarbonyl O-substituted poly(p-hydroxystyrene). 11. The process of claim 10 wherein the tertiary amine is present in the range from about 0.001 to 0.02 molar equivalents based on the dialkyl dicarbonate. 12. The process of claim 10 wherein the dimethylaminopyridine is selected from the group consisting of 2-dimethylaminopyridine and 4-dimethylaminopyridine. 13. The process of claim 10 wherein the degree of substitution is from 10-40%. 14. A process for preparing a microlithographically useful, stoichiometrically derivatized novolak resin having a degree of substitution of from 10-100% comprising the steps of (a) mixing together in a reaction vessel at ambient temperature (1) novolak resin, (2) a stoichiometric amount of di-tert-butyl dicarbonate to give the desired degree of substitution, and (3) a catalytic amount of a dimethylaminopyridine in a solvent for the reactants, with the proviso that the reaction mixture does not contain an organic amine base in an amount exceeding 0.02 molar equivalents based on the di-tert-butyl dicarbonate, and (b) stirring the reation mixture, (c) precipitating the t-butyloxycarbonyl O-substituted novolak resin, and (d) recovering the precipitated t-butyloxycarbonyl O-substituted novolak resin. 15. The process of claim 14 wherein the tertiary amine is present in the range from about 0.001 to 0.02 molar equivalents based on the dialkyl dicarbonate. 16. The process of claim 14 wherein the dimethylaminopyridine is selected from the group consisting of 2-dimethylaminopyridine and 4-dimethylaminopyridine. 17. The process of claim 14 wherein the degree of substitution is from 10-40%. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION The present invention relates to processes for carbonation (forming carbonates) of hydroxyaromatic compounds. The processes include the manufacturing of acid-labile group substituted polymers and monomers. These carbonated materials are useful in photoresist compositions and applications. BACKGROUND ART The use of phenolic polymers in photoresist compositions which are used in the fabrication of semiconductor devices is well known. Improvements in photoresists have created a need for resist components that have sufficient radiation or lithographic sensitivity to be of use in the fabrication of very large scale integration (VLSI) devices and ultra large scale integration (ULSI) devices. To meet these demands, chemically amplified photoresist compositions have been developed which generally comprise a polymer having acid sensitive functionalities and a compound which generates a strong acid upon radiation by UV light and/or electron beam (e beam) or x-ray radiation, referred to generally hereinafter as a "photoacid". The functionalized polymer reacts with the photoacid formed to fragment or release a portion of the functional group and regenerated acid to continue the photolysis or radiolysis reaction. Because a series of functional group changes can result from a single photon (or electron) absorbed, this process is referred to as "chemical amplification." U.S. Pat. No. 4,491,628 to Ito et al. is directed to resist compositions or formulations comprising a polymer having recurrent acid labile groups (such as t-butyl esters and t-butyl carbonates) pendant to the polymer chain and a photoacid such that the acid labile groups undergo cleavage from the polymer upon the radiation of the composition and release of the photoacid. The photoacid is generated by an onium salt. These compositions were found to exhibit particularly desirable properties for photolithography in that they are positive or negative working based solely on the choice of developer solvents. U.S. Pat. No. 4,552,833 to Ito et al. is directed to processes for generating negative images in a polymer film having masked reactive functionalities that is treated with an organometallic reagent after exposure and is dry developed with a reactive plasma after such treatment. U.S. Pat. No. 4,613,398 to Chiong et al. is directed to processes for removing acid labile groups from polymer materials and treatment with organometallic agents so that the films may be dry developed. U.S. Pat. No. 4,931,379 to Brunsvold et al. is directed to thermally stable resist compositions having secondary alkyl carbonates pendant to an aromatic group of a repeating polymer composition. U.S. patent application Ser. No. 07/264,407, filed Oct. 28, 1989, to Merritt et al., Attorney Docket No. FI9-88-037, discloses certain partially t-butyloxycarbonyloxy substituted poly(p-hydroxystyrenes) and methods for their manufacture. These methods include acidolysis and thermolysis of poly(p-t-butyloxycarbonyloxystyrenes) and amine catalyzed carbonation of poly(p-hydroxystyrene) with di-tert-butyl dicarbonate. Houlihan et al., Can. J. Chem., 63, 153 (1985), describes various mechanisms of phase transfer catalysis in the tert-butyloxycarbonylation of alcohols, phenols, enols, and thiols with di-tert-butyl dicarbonate. The tert-butyloxy-carbonylation of phenolic polymers such as poly-(p-hydroxystyrene) and novolaks was said to proceed rapidly and quantitatively with di-tert-butyl dicarbonate in THF, ethyl acetate, or dichloromethane, in the presence of a catalytic amount of crown ethers such as 18-crown-6 and an equivalent amount of powdered anhydrous potassium carbonate. It is an object of the present invention to provide an improved method to manufacture carbonated hydroxyaromatic compounds which provide a uniform product and near quantitative yields. Carbonated hydroxyaromatic (particularly t-butyloxycarbonyloxy substituted) polymers and monomers are especially useful in resists for use in photolithography. SUMMARY OF THE INVENTION In accordance with the present invention, a process for the precise and stoichiometric carbonation of a hydroxyaromatic material is provided which comprises the steps of (a) mixing together in a reaction vessel (1) a hydroxyaromatic material, (2) a sufficient amount of a dialkyl dicarbonate to give the desired degree of substitution, (3) a catalytic amount of an unhindered tertiary amine, and (4) a solvent, (b) stirring the reaction mixture, (c) precipitating the alkyl carbonate of the hydroxyaromatic material, and (d) recovering the alkyl carbonate of the hydroxyaromatic material. In this process, the hydroxy aromatic material may be a polymeric material such as a poly-(p-hydroxystyrene) or a novolak resin or it may be a monomeric phenol such as Bisphenol A or tris(hydroxyphenyl)ethane. The dialkyl dicarbonate is a primary, secondary or tertiary dicarbonate and include diethyldicarbonate di-cyclohexyldicarbonate, di-sec-butyldicarbonate, di-isopropyldicarbonate, di(2-pentyl)dicarbonate, di(substituted deactivated secondary benzyl) dicarbonate, di(1-(deactivatedheterocyclic)secondary-alkyl)dicarbonate, di-tert-butyl dicarbonate, or di-(t-amyl)dicarbonate. The unhindered tertiary amine may be dimethylaminopyridine, 4-pyrrolidino-pyridine, diethylmethylamine, trimethylamine, N-methylpyrrolidine, or a polymer having unhindered amino groups linked thereto. DETAILED DESCRIPTION It has been surprisingly found that the preparation of carbonated hydroxyaromatic compounds is enhanced by the use of a catalytic amount (i.e., not consumed in the reaction) of an unhindered tertiary amine to facilitate the reaction. As used herein catalytic amounts of tertiary amine are from about 0.02 to about 0.001 molar equivalent of the carbonates being substituted. (That it, the ratio of carbonate to tertiary amine is in the range from 50:1 to 1000:1.) The process of the invention is a precise stoichiometric reaction that enables the production of carbonated materials which have a lot to lot consistency that is not achieved in prior processes because residual base in the composition may react with and neutralize the photoacid while excess acid will promote the excess decarbonylation of the copolymer. The process is useful in obtaining a carbonate of an aromatic polymer or monomer having a degree of substitution from 10-100%. By "degree of substitution" it is meant that the percent of available hydroxyl groups have been converted to the desired carbonate. This process is of particular utility when the end-product is a partially derivatized poly-(p-hydroxystyrene) for use in photolithography. When a polymer having from 10-40% t-butyloxycarbonloxy substitution is desired, the process comprises change in a reaction vessel with poly(p-hydroxystyrene) and a stoichiometric fraction of di-tert-butyl dicarbonate in solvent for the reactants. A catalytic amount of an unhindered tertiary amine such as 2-dimethylamino pyridine or 4-dimethylamono-pyridine is added to the reaction mixture which is then stirred at ambient temperature until the copolymer of partially t-butyloxycarbonyl O-substituted poly(p-hydroxystyrene) is formed. Work up and recovery steps follow. The final material has consistant, reproducible lithographic properties due to the process simplification which avoids separation of reactants from final products. Thus any potential contamination due to environmental interactions with the reactants is avoided. The product is very consistent in terms of dissolution rate (DR) which is a function of the dialkyl dicarbonate used and the degree of substitution. The lithographic results are consistent in terms of dose-to-clear (DTC) and thinning. The invention is further exemplified by the examples which follow and which do not limit the scope of the invention that is disclosed. |
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