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Substantially improved photoresist material designs, which can provide higher photosensitivity and precise critical
dimension and edge roughness control, will be required to enable the application of next generation lithography
technology to the production of future sub-65 nm node IC device generations. The development and characterization of
novel material platforms that solve the aforementioned basic problems with chemically amplified resists (CARs) is
essential and is already one of the major subjects of modern lithography research. In that regard, we have pursued
development of a variety of 193 nm and EUV CARs that contain photoacid generator (PAG) units covalently bonded
directly to the resin polymer backbone. However, the detailed structure-property relationships that result from this
direct attachment of the PAG functional group to the polymer have previously not yet been rigorously characterized. In
this work, the lithographic properties of a polymer-bound PAG CAR (GBLMA-co-EAMA-co-F4-MBS.TPS) and its
blended-PAG analog resist (GBLMA-co-EAMA blend F4-IBBS.TPS) were studied and compared. The direct
incorporation of PAG functionality into the resist polymer, where the resulting photoacid remains bound to the polymer,
showed improved photosensitivity, resolution, and lower LER as compared with the analogous blended-PAG resist.
The improved resolution and LER were expected due to the restricted photoacid diffusion and uniform PAG distribution
provided by direct incorporation of the PAG into the polymer backbone to make a single-component resist material.
The ability to load higher levels of PAG into the resist provided by this PAG incorporation into the polymer, as compared
to the low PAG concentrations attainable by traditional blending approaches, overcomes the sensitivity loss that should
result from reduction in photoacid diffusivity and concomitant smaller acid-catalytic chain lengths. In fact, the
polymer-bound PAG resist achieves a faster photospeed than the blended-PAG analog material under DUV radiation in
the case of the materials reported here while still providing all of the aforementioned improvements such as the improved
line edge roughness.
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