Antireflective coating composition

1. An antireflective coating composition comprising a polymer, a crosslinker and a thermal acid generator, where the polymer comprises at least one unit of structure (1), at least one unit of structure (2) and at least one unit of structure (3),

where R 1 to R 9 is independently selected from H and C 1 -C 6 alkyl, R′ and R″ is independently selected from H and C 1 -C 6 alkyl, X is C 1 -C 6 alkylene, Y is C 1 -C 6 alkylene, further where the carbon content of the composition is in the range of about 75 weight % to about 85 weight %.

2. The antireflective coating composition of claim 1 , where the unit of structure (1) is in the range of about 20 mole % to about 35 mole %.

3. The antireflective coating composition of claim 1 , where the refractive index value is in the range of about 1.5 to about 1.8 at 193 nm.

4. The antireflective coating composition of claim 1 , where X is methylene.

5. The antireflective coating composition of claim 1 , where Y is ethylene.

6. The antireflective coating composition of claim 1 , where R″ is hydrogen.

7. The antireflective coating composition of claim 1 , where the polymer has the structure comprising units 4, 5 and 6,

8. The antireflective coating composition of claim 1 , where the crosslinker is selected from melamines, methylols, glycolurils, polymeric glycolurils, hydroxy alkyl amides, epoxy and epoxy amine resins, blocked isocyanates, polymeric crosslinkers, and divinyl monomers.

9. The composition of claim 1 , where the thermal acid generator is selected from alkyl ammonium salts of organic acids, phenolic sulfonate esters, nitrobenzyl tosylates, and metal-free iodonium and sulfonium salts.

10. The composition of claim 1 , where the polymer is soluble in a solvent comprising PGME.

11. The composition of claim 1 , further comprising a second polymer.

12. The composition of claim 1 , further comprising a second polymer comprising 4 or more fused aromatic rings.

13. A process for forming an image comprising,

a) coating and baking a substrate with the antireflective coating composition of claim 1 ;

b) coating and baking a photoresist film on top of the antireflective coating;

c) imagewise exposing the photoresist to radiation;

d) developing an image in the photoresist;

e) optionally, baking the substrate after the exposing step.

14. The process of claim 13 , where the photoresist is imagewise exposed at wavelengths between 130 nm to 250 nm.

15. The process of claim 13 , where the photoresist comprises a polymer and a photoactive compound.

16. The process of claim 13 , where the antireflective coating is baked at temperatures greater than 90° C.

17. The process of claim 13 , where additional layer(s) of antireflective coating are formed over the antireflective coating.

18. An antireflective coating composition comprising a polymer, a crosslinker and a thermal acid generator, where the polymer comprises at least one unit of structure (1), at least one unit of structure (2) and at least one unit of structure (3),

where R 1 to R 9 is independently selected from H and C 1 -C 6 alkyl, R′ and R″ is independently selected from H and C 1 -C 6 alkyl, X is C 1 -C 6 alkylen, Y is C 1 -C 6 alkylene, further where the absorption parameter is in the range of about 0.3 to about 0.7 at 193 nm.