content_image/936263.jpg content_image/936245.jpg content_image/936265.jpg content_image/936264.jpg
filtered by 0.2 um Nylon filter. A 60 run film of CTOl was spin-coated on resist with 45 run 1: 1 line and space patterns, baked at 70° C., and developed in 2.38% TMAH developer for 12 s with TEL Lithus GP nozzle. 

## Chemical Trim Overcoat Composition (CTO2) 

2.324 g copolymer of t-butyl acrylate/methacrylic acid 10 (7 /3 of mole ratio), 0.126 g of Pyridinium perfluorobutane› sulfonate, 19.51 g decane and 78.04 g 2-methyl-1-butynol were mixed until all components dissolved and then filtered by 0.2 um Nylon filter. A 60 run film of CTO2 was spin-coated on resist with 45 run 1: 1 line and space patterns, 15 baked at 70° C. and developed in 2.38% TMAH developer for 12 s with TEL Lithus GP nozzle. 

## CTO Comparative Example (for Comparison with CTOl) 

2.323 g copolymer of t-butyl acrylate/methacrylic acid (7/3 of mole ratio), 0.127 g of Pyridazinium perfluorobu- tanesulfonate, 19.51 g decane and 78.04 g 2-methyl-1- butynol were mixed until all components dissolve and then filtered by 0.2 um Nylon filter. A 60 run film of CTOl (Example 3) was spin-coated on resist with 45 run 1:1 line and space patterns, baked at 70° C. and developed in 2.38% TMAH developer for 12 s with TEL Lithus GP nozzle. 

## CTO Comparative Example (for Comparison with CTO2) 

2.344 g copolymer of t-butyl acrylate/methacrylic acid (7 /3 of mole ratio), 0.106 g of Ammonium perfluorobutane› sulfonate, 19.51 g decane and 78.04 g 2-methyl-1-butynol were mixed until all components dissolve and then filtered by 0.2 um Nylon filter. A 60 run film of CTO2 was spin-coated on resist with 45 run 1: 1 line and space patterns, baked at 70° C. and developed in 2.38% TMAH developer for 12 s with TEL Lithus GP nozzle. 

Results are set forth in Table 1. 

<img src='content_image/936263.jpg'>

The CD shrink values shown in Table 1 confirm that the CTO composition with an ammonium TAG (Example 6) exhibits no CD shrink at this temperature, whereas the pyridinium TAG (CTO2) shows 11.5 run shrink. Without wishing to be bound by theory, it is believed that the lack of CD shrink in the composition with the ammonium TAG is due to the high pKa of ammonia (9.25), whereas the pyri- dinium TAG of Example 5 has a lower pKa. The 3-fluoro› pyridinium TAG (CTOl, Example 3) shows an even greater 

## Example 4 

## Example 5 

## Example 6 

CD shrink than the pyridinium TAG, and, without wishing to be bound by theory, it is believed that this is due, at least in part, to the lower pKa of3-fluoropyridine vs. pyridine (at similar boiling point). 

Comparative Example 5 uses a TAG made from pyridazine, a base with a pKa similar to that of 3-fluoro› pyridine, but a 100° C. higher boiling point. As shown in Table 1, the pyridazinium TAG results in relatively small shrink. 

What is claimed is: 

1. A method for providing a photoresist relief image, comprising: 

a) applying a coating layer of a chemically amplified photoresist composition on a substrate; 

b) exposing the photoresist layer to activating radiation and developing the exposed photoresist layer to provide a photoresist relief image; 

c) applying over the exposed photoresist composition coating layer a coating layer of a chemical trim over› coat composition comprising a thermal acid generator of formula (I); 

<img src='content_image/936245.jpg'>

in which 

A- is the anion of an organic or inorganic acid having a pKa of not more than 3; and 

(BHt is the monoprotonated form of a nitrogen-contain› ing base B having a pKa between O and 5.0, and a boiling point less than 170° C.; 

d) heating the chemical trim overcoat composition layer; and 

e) developing the photoresist layer to provide a photore› sist relief image. 

2. The method of claim 1 wherein B is selected from the group consisting of: 

<img src='content_image/936265.jpg'>

<img src='content_image/936264.jpg'>

-continued 

