Photoresist composition for imaging thick films
View Patent ↗The present invention provides for a light-sensitive photoresist composition useful for imaging thick films, comprising a polymer which is insoluble in an aqueous alkali developer but becomes soluble prior to development, a photoacid generator which produces a strong acid upon irradiation and a photobleachable dye. The invention further provides for a process for imaging the photoresist of the present invention, especially where the thickness of the photoresist is up to 200 microns and where the process comprises a single exposure step.
1. A photoresist composition comprising a polymer which is insoluble in an aqueous alkali developer but becomes soluble prior to development, a photoacid generator which produces a strong acid upon irradiation and a photobleachable dye which is absorbing at the same radiation as the photoacid generator, further where the photoacid generator is an imide and the photobleachable dye is a naphthoquinone diazide.
2. The photoresist according to claim 1 , where the photobleachable dye has a similar or lower rate of photobleaching than the photoacid generator.
3. The photoresist according to claim 1 , where the polymer is an aqueous alkali soluble polymer protected with an acid labile group.
4. The photoresist according to claim 1 , where the polymer comprises at least one unit derived from monomers selected from hydroxy styrene, acrylate capped with an acid labile group, methacrylate capped with acid labile group, hydroxy styrene capped with an acid labile group, styrene, acetoxystyrene, methoxystyrene, and mixtures thereof.
5. The photoresist according to claim 1 , where the photoacid generator produces a sulfonic acid upon exposure.
6. The photoresist according to claim 1 , where the photoacid generator is a sulfonyloxy imide or imidosulfonate.
7. The photoresist according to claim 1 , where the photobleachable dye is 2,1,5, and/or 2,1,4, naphthoquinone diazide.
8. The photoresist according to claim 1 , where the composition further comprises a novolak resin.
9. The photoresist according to claim 1 , where the composition further comprises a base.
10. The photoresist according to claim 1 , where the composition further comprises a plasiticizer.
11. A process for imaging a photoresist comprising the steps of:
a) forming on a substrate a coating of a photoresist composition from claim 1 ;
b) image-wise exposing the photoresist coating with radiation;
c) postexposure baking the photoresist coating;
d) developing the photoresist coating with an aqueous alkaline developer to form photoresist structures.
12. The process of claim 11 , where the photoresist coating has a film thickness less than 200 microns.
13. The process of claim 11 , where the photoresist coating is exposed in a single step.
14. The process of claim 11 , where the photoresist is imaged with radiation from 300 nm to 450 nm.
15. The process of claim 11 , where the photoresist structures have an aspect ratio of greater than 3.
16. The process of claim 11 , where the developer is an aqueous solution of tetramethylammonium hydroxide.
17. The composition of claim 1 , where the imide is a sulfonyloxyimide or imidosulfonate.