We investigated the etch rates of various polymers etch rates, and found that alicyclic polymers show a good dry etch resistance in spite of the lack of the aromatic rings. On the basis of this finding we proposed a new ArF resist material which has good transparency and good dry etch resistance for use as a single layer resist.. The resist comprises an alicyclic copolymer of adamantyl methacrylate (AdMA) and 3-oxocyclohexyl methaclyrate (OCMA) and a triphenylsulphonium hexafuluoroantimonate as a photoacid generator (PAG). The transmittance of the 1μm thick copolymer is about 70% at ArF wavelength. This high transparency ensures pattern imaging of the resist in ArF lithography. The dry etch resistance of the resist is also high and is comparable to that of Novolak resist. We obtained 0.17μm line and space patterns with this resist, using ArF excimer laser stepper.
The Technical Association of Photopolymers, Japan