Photoresist composition for deep ultraviolet lithography

Inactive Publication Date: 2004-08-26
AZ ELECTRONICS MATERIALS USA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

U.S. Pat. No. 5,843,624 discloses polymers for photoresist that are obtained by free radical polymerization of maleic anhydride and unsaturated cyclic monomers, but the presence of maleic anhydride makes these polymers insufficiently transparent at 157 nm.
These materials give acceptable absorbance at 157 nm, but due to their lower alicyclic content as compared to the fluoro-norbornene polymer, have lower plasma etch resistance.
However, an important limitation to any of these approaches is the availability of a suitable protecting group for fluoroalcohols.
These protect

Method used

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  • Photoresist composition for deep ultraviolet lithography
  • Photoresist composition for deep ultraviolet lithography
  • Photoresist composition for deep ultraviolet lithography

Examples

Experimental program
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Effect test

example 1

[0090] Table 1 shows the TGA onset of deprotection of MOM and t-boc compared to that found for the deprotection with the BOCME group on representative examples of polymers (FIG. 6) belonging to the two classes of cyclic fluoroalcohol bearing polymer described earlier.

1TABLE 1 Onset of deprotection of polymers I and II with various protecting groups* Protecting Polymer Onset of group (% protection) Deprotection (.degree. C.) BOCME II (30%) 174 BOCME I (30%) 206 T-BOC I (30%) 120 MOM II (20%) <100 *Data gathered at 20.degree. C. / min heating rate

[0091] Table 1 clearly shows that polymers with the BOCME group thermally deprotect at a higher temperature than the same polymer with the t-boc and MOM groups

example 2

[0092] The contrasts of resists were measured by coating them at a thickness of 1350 A (Angstroms) and after exposure using an open frame reticle baking and developing the film and measuring the normalized thickness as a function of dose. The contrast is taken from the slope of plot of normalized thickness versus log(dose). Processing conditions were as follows:

[0093] The exposures were done an Exitech 157 nm small field (1.5.sub.--1.5 mm2) mini-stepper (0.6 NA) using open frame exposure reticle at International SEMATECH in Austin. An FSI Polaris 2000 track was used to coat, bake, and develop the resist films. A Prometrix interferometer was used to measure resist thickness.

[0094] The photoresist formulations preparation and resultant contrasts are as follows:

[0095] By mixing the following dry ingredients poly(tert-Butyl Bicyclo[2.2.1]hept-5-ene-2-carboxylate-co-1,1,1-trifluoro-2-(trifluoromet-hyl)pent-4-en-2-3-(Bicyclo[2.2.1]hept-5-en-2-yl)-1,1,1-trifluoro-2-(triflu-oromethyl)propan...

example 3

Synthesis of BOCME Protected Poly(3-(bicyclo[2.2.1]hept-5-en-2-yl)-1,1,1-t-rifluoro-2-(trifluoromethyl)propan-2-ol) Using t-BuOK

[0096] Poly(3-(bicyclo[2.2.1]hept-5-en-2-yl)-1,1,1-trifluoro-2-(trifluorom-ethyl)propan-2-ol) (PBHTTP) (4.0 g, 14.59 mmol) was dissolved into 15 ml of tetrahydrofuran (THF), and solid t-BuOK (0.491 g, 4.38 mmol) was added while stirring. After 30 minutes, t-butyl bromoacetate (1.71 g, 8.76 mmol) was added to this reaction solution which was stirred for 16 hours at 25.degree. C. After removal of the solvent using a rotary evaporator, the resultant residue was dissolved in 20 ml of methanol (MeOH) containing 1.0 g of concentrated HCl. This solution was then precipitated in 180 ml of water-methanol (8:1). The polymer was isolated by filtration and further purified by dissolving it into MeOH and re-precipitating it in the water-methanol mixture. The final precipitate was then filtered, washed with water and dried overnight under vacuum (25" Hg) at 55.degree. C....

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Abstract

The present invention relates to a photoresist composition comprising a photoacid generator and at least one novel polymer comprising at least one unit as described by structure 1, where, either (i) R1 is an aliphatic cyclic unit of a polymer, R2 is selected from H, F, (C1-C8)alkyl, (C1-C8)fluoroalkyl, cycloalkyl, cyclofluoroalkyl, and (CR3R4)p(CO)OR5, and Rf is selected from F, H, (C1-C8)alkyl, or a fully or partially fluorinated alkyl, and cyclofluoroalkyl, or (ii) R1 and R2 combine to form an aliphatic cyclic unit of a polymer, and Rf is selected from F, H, (C1-C8)alkyl and a fully or partially fluorinated alkyl, and cyclofluoroalkyl, or (ii) R1 and Rf combine to form an aliphatic cyclic unit of a polymer, and R2 is selected from H, F, (C1-C8)alkyl, (C1-C8)fluoroalkyl, cycloalkyl, cyclofluoroalkyl, and (CR3R4)p(CO)OR5; and, R3 and R4 are independently H, F, (C1-C8)alkyl, (C1-C8)fluoroalkyl, cycloalkyl, cyclofluoroalkyl, (CR3R4)p(CO)OR5, R3 and R4 may combine to form an alkylspirocyclic or a fluoroalkylspirocyclic group, X is selected from (C1-C8)alkylene, (C1-C8)fluoroalkylene, O(C1-C8)alkylene, O(C1-C8)fluoroalkylene, cycloalkyl and fluorinatedcycloalkyl, R5 is H or an acid labile group, m=0-1, and p=1-4. The invention also relates to a process for imaging the photoresist composition of the present invention.

Description

[0001] The present invention relates to a novel photoresist composition that is particularly useful in the field of microlithography, and especially useful for imaging positive patterns in the production of semiconductor devices. The photoresist resin composition comprises a polymer or a mixture of polymers in which fluoro-alcohol moieties on an aliphatic cyclic fluorinated polymer are fully or partially protected with an alkyloxycarbonylalkyl (AOCA) protecting group, a photoactive component, and optionally, a base additive. The resin of the novel photoresist has high transparency in the deep ultraviolet (uv) region, and such a composition is especially useful for exposure at 193 nanometers (nm) and 157 nm. The invention further relates to a process for imaging the novel photoresist.BACKGROUND OF INVENTION[0002] Photoresist compositions are used in microlithography processes for making miniaturized electronic components such as in the fabrication of computer chips and integrated cir...

Claims

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Application Information

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IPC IPC(8): G03F7/004G03F7/039
CPCG03F7/0046G03F7/0395Y10S430/111Y10S430/108Y10S430/106
Inventor DAMMEL, RALPH R.SAKAMURI, RAJHOULIHAN, FRANK
Owner AZ ELECTRONICS MATERIALS USA CORP
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