Coating compositions suitable for use with an overcoated photoresist

Abstract

Organic coating compositions, particularly antireflective coating compositions, are provided that can be developed with an aqueous alkaline developer, including in a single step during development of an overcoated photoresist layer. Preferred coating compositions comprise a tetrapolymer that comprises at least four distinct functional groups.

Claims

1. An antireflective composition for use with an overcoated photoresist layer, comprising: a tetrapolymer that comprises polymizerized units of maleimide, 9-anthracene-methyl methacrylate, 2-hydroxynaphthalene-methylmethacrylate, and t-butyl acrylate.

2. The composition of claim 1 wherein the coating composition further comprises an acid or acid generator compound.

3. The composition of claim 1 wherein the coating composition further comprises a photoacid generator compound.

4. A method for forming a photoresist relief image comprising: (a) applying over a substrate a coating layer of antireflective composition of claim 1; and (b) applying a photoresist layer above the coating composition layer.

5. The method of claim 4 wherein the coating composition further comprises an acid or acid generator compound.

6. The method of claim 4 wherein the coating composition further comprises a photoacid generator compound.

7. The method of claim 4 wherein the antireflective coating composition layer is not crosslinked at the time the photoresist layer is applied.

8. The method of claim 4 wherein the applied photoresist layer is exposed to patterned radiation and then developed with an aqueous alkaline developer composition, whereby the developer composition selectively removes in both the photoresist layer and the underlying coating composition layer the image as defined in the photoresist layer by patterned radiation.

Description

Example 1

Synthesis of MI/ANTMA/HNMA-2/TBA 34.3/31.5/25.0/9.2 tetrapolymer

(1) Into a 2.0 L, 5-necked round bottom flask, fitted with a mechanical stirrer, condenser, heating mantle, and temperature controller, were added 215 g dioxane. The solvent was sparged with nitrogen gas for 15 minutes. The solvent was heated to 85° C.

(2) Into a 2.0 L Erlenmeyer flask with stir bar were added maleimide (MI, 53.10 g, 547 mmol), 9-anthracene-methyl methacrylate (ANTMA, 138.7 g, 502 mmol), 2-hydroxynaphthalene-methylmethacrylate monomer (HNMA-2, 96.53 g, 398 mmol), t-butyl acrylate (TBA, 18.80 g, 147 mmol) and dioxane (423.5 g). The mixture was allowed to stir at room temperature for 30 minutes. The solution was sparged with nitrogen gas for 15 minutes.

(3) Into a 500 mL bottle were added 2,2-azobis(2,4-dimethylvaleronitrile (Vazo® 52, 11.89 g, 48.0 mmol) and dioxane (78.0 g).

(4) The monomer solution was fed to the reaction flask with a peristaltic pump over 1.5 hours at a rate of 8.5 g/min. The initiator solution was also fed to the reaction flask with a peristaltic pump over this period at a rate of 1.1 g/min (90 min feed).

(5) Upon completion of the monomer and initiator feed, a solution of 2,2-azobis(2,4-dimethylvaleronitrile (Vazo® 52, 7.93 g, 32.0 mmol) and dioxane (151 g) was fed to the reaction flask with a peristaltic pump over 20 minutes at a rate of 8.0 g/min.

(6) When complete, the reaction mixture was held at 85° C. for 1.5 hours.

(7) After cooling to room temperature, the reaction mixture was precipitated into 15.0 L of methanol. The white precipitate was isolated by vacuum filtration, washed with 3.0 L of methanol and dried in a vacuum oven overnight at 50° C.

(8) 195.1 g (64%) of the title polymer was obtained as a white powder. GPC (THF) M.sub.w=9300 Da, M.sub.n=6500 Da, PDI: 1.5.

Example 2

Synthesis of MI/ANTMA/HNMA-2/TBA 33.2/31.3/26.8/8.7 tetrapolymer

(9) Into a 2.0 L, 5-necked round bottom flask, fitted with a mechanical stirrer, condenser, heating mantle, and temperature controller, were added 218 g dioxane. The solvent was sparged with nitrogen gas for 15 minutes. The solvent was heated to 85° C.

(10) Into a 2.0 L Erlenmeyer flask with stir bar were added maleimide (MI, 51.39 g, 529 mmol), 9-anthracene-methyl methacrylate (ANTMA, 137.9 g, 499 mmol), 2-hydroxynaphthalene-methylmethacrylate monomer (HNMA-2, 103.4 g, 427 mmol), t-butyl acrylate (TBA, 17.82 g, 139 mmol) and dioxane (430 g). The mixture was allowed to stir at room temperature for 30 minutes. The solution was sparged with nitrogen gas for 15 minutes.

(11) Into a 500 mL bottle were added 2,2-azobis(2,4-dimethylvaleronitrile (Vazo® 52, 11.89 g, 48.0 mmol) and dioxane (78.0 g).

(12) The monomer solution was fed to the reaction flask with a peristaltic pump over 1.5 hours at a rate of 7.5 g/min. The initiator solution was also fed to the reaction flask with a peristaltic pump over this period at a rate of 0.9 g/min (90 min feed).

(13) Upon completion of the monomer and initiator feed, a solution of 2,2-azobis(2,4-dimethylvaleronitrile (Vazo® 52, 7.93 g, 32.0 mmol) and dioxane (151 g) was fed to the reaction flask with a peristaltic pump over 20 minutes at a rate of 8.2 g/min.

(14) When complete, the reaction mixture was held at 85° C. for 1.5 hours.

(15) After cooling to room temperature, the reaction mixture was precipitated into 15.0 L of methanol. The white precipitate was isolated by vacuum filtration, washed with 3.0 L of methanol and dried in a vacuum oven overnight at 50° C.

(16) 186.6 g (60%) of the tile polymer was obtained as a white powder. GPC (THF) M.sub.w=9200 Da, M.sub.n=6350 Da, PDI: 1.5.

Example 3

Coating Composition Preparation and Lithographic Processing

(17) An underlying coating composition is prepared by admixing the following materials:

(18) Reaction Component (Resin)

(19) Polymer of Example 1 above

(20) Photoacid Generator

(21) triphenyl sulfonium salt

(22) Solvent

(23) ethyl lactate

(24) The reaction component was percent in an amount of 5 grams. The photoacid generator compound is present in an amount of about 0.5 weight percent of total solids (all components expect solvent).

(25) This formulated coating composition is spin coated onto a silicon microchip wafer and is cured at 210° C. for 60 seconds on a vacuum hotplate to provide a dried (but not cross-linked) coating layer.

(26) A commercially available 193 nm positive-acting photoresist is then spin-coated over the cured coating composition layer. The applied resist layer is soft-baked at 100° C. for 60 seconds on a vacuum hotplate, exposed to patterned 193 nm radiation through a photomask, post-exposure baked at 110° C. for 60 seconds and then developed with 0.26 N aqueous alkaline developer where both the photoresist later and underlying coating composition are removed in areas defined by the photomask.

Example 4

Coating Composition Preparation and Lithographic Processing

(27) An underlying coating composition is prepared by admixing the following materials:

(28) Tetrapolymer Reaction Component

(29) Polymer of Example 2 above

(30) Photoacid Generator

(31) triphenyl sulfonium salt

(32) Solvent

(33) ethyl lactate

(34) The reaction component was percent in an amount of 5 grams. The photoacid generator compound is present in an amount of about 0.5 weight percent of total solids (all components expect solvent).

(35) This formulated coating composition is spin coated onto a silicon microchip wafer and is cured at 210° C. for 60 seconds on a vacuum hotplate to provide a dried (but not cross-linked) coating layer.

(36) A commercially available 193 nm positive-acting photoresist is then spin-coated over the cured coating composition layer. The applied resist layer is soft-baked at 100° C. for 60 seconds on a vacuum hotplate, exposed to patterned 193 nm radiation through a photomask, post-exposure baked at 110° C. for 60 seconds and then developed with 0.26 N aqueous alkaline developer where both the photoresist later and underlying coating composition are removed in areas defined by the photomask.

Example 5

Coating Composition Preparation and Lithographic Processing

(37) An underlying coating composition is prepared by admixing the following materials:

(38) Tetrapolymer Reaction Component

(39) Polymer Blend of Examples 1 and 2 above

(40) Photoacid Generator

(41) triphenyl sulfonium salt

(42) Solvent

(43) ethyl lactate

(44) The reaction component was percent in an amount of 5 grams. The photoacid generator compound is present in an amount of about 0.5 weight percent of total solids (all components expect solvent).

(45) This formulated coating composition is spin coated onto a silicon microchip wafer and is cured at 210° C. for 60 seconds on a vacuum hotplate to provide a dried (but not cross-linked) coating layer.

(46) A commercially available 193 nm positive-acting photoresist is then spin-coated over the cured coating composition layer. The applied resist layer is soft-baked at 100° C. for 60 seconds on a vacuum hotplate, exposed to patterned 193 nm radiation through a photomask, post-exposure baked at 110° C. for 60 seconds and then developed with 0.26 N aqueous alkaline developer where both the photoresist later and underlying coating composition are removed in areas defined by the photomask.

Example 6

Coating Composition and Lithographic Processing

(47) A coating composition was prepared by admixing the following components: materials:

(48) Tetrapolymer Reaction Component

(49) Polymer Blend of Examples 1 and 2 above

(50) Photoacid Generator

(51) triphenyl sulfonium salt

(52) Solvent

(53) methyl 2-hydroxyisobutyrate

(54) In this coating come coating composition, the reaction component (resin) is present in an amount of 3.2 grams, the acid source (thermal acid generator) is present at about 0.8 weight percent of total solids and an photoacid generator is present at about 2% weight percent of total solids (all materials except solvent). The solvent is present in an amount of about 96 weight percent of the total coating composition weight.

(55) This coating composition is spin coated onto a silicon wafer substrate and baked at 215° C. to remove solvent, but does not result in crosslinking of the coating composition layer.

(56) A 193 nm photoresist composition is spin-coated over the coating composition and regions of the photoresist composition were exposed to 193 nm radiation at varying energy doses. The exposed photoresist layer is then post-exposure baked at about 110° C. for 60 seconds and the baked photoresist layers are developed with 0.26N tetramethyl ammonium hydroxide (TMAH) aqueous alkaline developer where both the photoresist later and underlying coating composition are removed in areas defined by the photomask.

Example 7

Test to Confirm that Thermal Treatment of an Underlying Coating Composition does not Result in Crosslinking (Molecular Weight Increase of Composition Components)

(57) A solution of a polymer containing polymerized units of maleimide, polyhydroxystyrene and 9-anthracene-methyl methacrylate were spin cast onto 8″ silicon wafers and baked at 180° C. and 240° C. An unbaked coating of each material was also prepared. Formulations containing the same polymer but also a photoacid generator compound were also prepared and coatings were made on 8″ silicon wafers at the same bake temperatures (room temperature, 180° C. and 240° C.). After processing as described above, all of the coated films were scraped, readily dissolved in THF and molecular weight measured by GPC.

(58) The weight-average molecular weight data for the polymer films with and without PAG showed minimal change after thermal processing thus indicating that crosslinking did not take place upon the thermal treatments.

(59) The foregoing description of this invention is merely illustrative thereof, and it is understood that variations and modifications can be made without departing from the spirit or scope of the invention as set forth in the following claims.