Photoresist undercoat-forming material and patterning process
A material comprising a specific bisphenol compound of formula (1) is useful in forming a photoresist undercoat wherein R 1 and R 2 are H, alkyl, aryl or alkenyl, R 3 and R 4 are H, alkyl, alkenyl, aryl, acetal, acyl or glycidyl, R 5 and R 6 are alkyl having a ring structure, or R 5 and R 6 bond together to form a ring. The undercoat-forming material has an extinction coefficient sufficient to provide an antireflective effect at a thickness of at least 200 nm, and a high etching resistance as demonstrated by slow etching rates with CF 4 /CHF 3 and Cl 2 /BCl 3 gases for substrate processing.
1. A photoresist undercoat-forming material comprising a resin comprising recurring units derived by novolac formation of a bisphenol compound selected from the group consisting of the following formulae:
wherein R 1 and R 2 are each independently hydrogen, a straight, branched or cyclic C 1 -C 10 alkyl group, C 6 -C 10 aryl group or C 2 -C 10 alkenyl group,
R 3 and R 4 are each independently hydrogen, a straight, branched or cyclic C 1 -C 6 alkyl group, straight, branched or cyclic C 2 -C 6 alkenyl group, C 6 -C 10 aryl group, C 2 -C 6 acetal group, C 2 -C 6 acyl group or glycidyl group.
2. The material of claim 1 , further comprising an organic solvent.
3. The material of claim 1 , further comprising a crosslinker and an acid generator.
4. A patterning process comprising the steps of:
applying the photoresist undercoat-forming material of claim 1 onto a processable substrate to form an undercoat layer,
applying a photoresist composition onto the undercoat layer to form a photoresist layer,
exposing the photoresist layer in a predetermined region to radiation,
developing the photoresist layer with a developer to form a photoresist pattern, and
processing the undercoat layer and the substrate through the patterned photoresist layer as a mask, by means of a dry etching apparatus.
5. The patterning process of claim 4 , wherein said photoresist composition comprises a silicon atom-containing polymer, and the processing step includes dry etching the undercoat layer through the photoresist layer as a mask with an oxygen-based etchant gas.
6. A patterning process comprising the steps of:
applying the photoresist undercoat-forming material of claim 2 onto a processable substrate to form an undercoat layer,
applying a silicon atom-containing intermediate layer over the undercoat layer,
applying a photoresist composition onto the intermediate layer to form a photoresist layer,
exposing the photoresist layer in a predetermined region to radiation,
developing the photoresist layer with a developer to form a photoresist pattern,
processing the intermediate layer through the patterned photoresist layer as a mask,
removing the patterned photoresist layer, and
processing the undercoat layer and then the substrate through the processed intermediate layer as a mask,
the processing steps using a dry etching apparatus.
7. The patterning process of claim 6 , wherein said photoresist composition comprises a silicon atom-free polymer, and the step of processing the undercoat layer includes dry etching with an oxygen-based etchant gas.