Cholate photoacid generators and photoresists comprising same

Abstract

New photoacid generator compounds (PAGs) are provided that comprise a cholate moiety and photoresist compositions that comprise such PAG compounds.

Claims

1. A photoacid generator compound of the following formula (III):
(R)X(CO)O(CH.sub.2).sub.m(CWY).sub.nSO.sub.3M.sup.+(III) wherein R is a steroid structure, X is a linker; W and Y are each independently in each occurrence hydrogen or fluoro; M.sup.+ represent an organic onium group; m is an integer of 1 to 10; n is 2.

2. A photoacid generator compound of the following formula (IV):
(R)XO(CO)(CH.sub.2).sub.m(CWY).sub.nSO.sub.3M.sup.+(IV) wherein R is a steroid structure, X is a linker; W and Y are each independently in each occurrence hydrogen or fluoro; M.sup.+ represent an organic onium group; m is an integer of 1 to 10; n is a positive integer.

3. A photoacid generator compound selected from: ##STR00010## wherein in each structure, m is an integer from 1 to 10, n is 2, M.sup.+ represents an organic onium group, and the definition of the group R, is defined directly below the respective structure.

4. A photoresist composition comprising a resin component and a photoacid generator compound of claim 1.

5. A photoresist composition comprising a resin component and a photoacid generator compound of claim 2.

6. A photoresist composition comprising a resin component and a photoacid generator compound of claim 3.

7. A method for forming a photoresist relief image comprising: (a) applying a coating layer of a photoresist composition of claim 4 on a substrate; (b) exposing the photoresist coating layer to patterned activating radiation and developing the exposed photoresist layer to provide a relief image.

8. A method for forming a photoresist relief image comprising: (a) applying a coating layer of a photoresist composition of claim 5 on a substrate; (b) exposing the photoresist coating layer to patterned activating radiation and developing the exposed photoresist layer to provide a relief image.

9. A method for forming a photoresist relief image comprising: (a) applying a coating layer of a photoresist composition of claim 6 on a substrate; (b) exposing the photoresist coating layer to patterned activating radiation and developing the exposed photoresist layer to provide a relief image.

Description

EXAMPLE 1: SYNTHESIS OF TPS DHC TFBS

(1) The three steps synthesis of TBPTMS 30H-Ad TFBS is described in the Scheme B.

(2) The details synthetic procedures for each step are outlined below.

(3) ##STR00008## ##STR00009##
Step 1: Synthesis of DHC-TFBBr:

(4) To a 3 L flask were added 120 g of Dehydrocholic acid (298.12 mmol), 50.7 g of 1,1-carbonyldiimidazole (CDI) and 1800 mL toluene under a nitrogen sweep. The mixture was held at room temp for 2-3 hrs. The mixture was heated to reflux, then 70.40 g of 4-bromo-3,3,4,4-tetrafluoro-butan-1-ol (312.9 mmol) was added over a 5 min period. The mixture slowly becomes an amber colored solution with overnight heating. The reaction was cooled to 25 C, added to a separatory funnel then washed with water (10800 ml) until the pH was equal to the pH of the DI water. To the top (amber colored) toluene layer was added MgSO.sub.4 and 15 g of activated charcoal. This mixture was stirred for 2 hrs and then filtered. The filtrate (toluene) was removed under reduced pressure resulting in a white solid. This solid was vacuum dried at 70 C for 18 hrs leaving 136 g of product (75% yield). The product DHC-TFBBr was used in step 2.

(5) Step 2: Synthesis of DHC-TFBSNa:

(6) The product DHC-TFBBr (136 g) from step 1 was combined in a 3 L flask with 78 g sodium thiosufite, 56.8 g sodium bicarbonate, 1300 ml of acetonitrile and 650 ml of deionized water. This mixture was held at 60 C for 16 hrs. The mixture was cooled to room temp. The acetonitrile layer was collected and placed in a 2 L flask and the water was azeotroped off by removing 50% of the acetonitrile. Any salts which precipitated out were removed and the filtrate was poured into 10 L of methyl t-butyl ether. The solid was collected by filtration and dried. 138.5 g of sulfinate salt was obtained which were added to a mixture of 750 ml of acetonitrile and 350 ml of DI water. To the mixture was added 150 mg of NaWO.sub.4.2H.sub.2O and 38.2 g of 30% hydrogen peroxide. The solution was stirred for 2-3 hrs at room temp. The product DHC-TFBSNa was obtained after usual workup as colorless solid. Yield 100 g (71%). The product was used in the 3red step.

(7) Step 3: Synthesis of TPS DHC-TFBS:

(8) A mixture made of 111 g of DHC-TFBSNa, 60.50 g of triphenyl sulfonium bromide in 750 ml methylene chloride and 100 ml of deionized water was stirred at room temperature for 18 hours. The layers were separated and the bottom organic layer was washed with 10500 ml of deionized water. The methylene chloride was dried over MgSO.sub.4 then reduced in volume by 40%. The methylene chloride solution was slowly added to 10 L of Methyl t-butyl ether. The solid was collected and dried leaving 139 g of TPS DHC-TFBS. The product was refluxed overnight in 500 ml of MTBE, collected and dried leaving 131 g of analytically pure product.

EXAMPLE 3: PHOTORESIST PREPARATION AND LITHOGRAPHIC PROCESSING

(9) A photoresist of the invention is prepared by mixing the following components with amounts expressed as weight percent based on total weight of the resist compositions:

(10) TABLE-US-00001 Resist components Amount (wt. %) Resin binder 15 Photoacid generator 4 Ethyl lactate 81

(11) The resin binder is a terpolymer (2-methyl-2-adamantyl methacrylate/beta-hydroxy-gamma-butyrolactone methacrylate/cyano-norbornyl methacrylate. The photoacid generator is the compound TPS DHC-TFBS, as prepared in Example 1 above. Those resin and PAG components are admixed in the ethyl lactate solvent.

(12) The formulated resist composition is spin coated onto HMDS vapor primed 4 inch silicon wafers and softbaked via a vacuum hotplate at 90 C. for 60 seconds. The resist coating layer is exposed through a photomask at 193 nm, and then the exposed coating layers are post-exposure baked at 110 C. The coated wafers are then treated with 0.26N aqueous tetrabutylammonium hydroxide solution to develop the imaged resist layer.