No abstract

A method for measuring acid generation efficiency is presented and utilized to determine the relative efficiency of four photoacid generators (PAGs) upon radiation with photon, electron, and ion beams. In this method, chemically amplified resists are prepared with varying amounts of base, coated into thin films (1000 AA), and exposed. Linear plots of the base concentration against the threshold exposure dose for each resist yield the threshold acid concentration and the acid generation rate constant for each PAG. The acid-generating efficiency of the four PAGs (ND-Tf, TPS-Tf, TBI-PFOS, and TBI-Tf) upon irradiation with DUV (248 nm), EUV (13.4 nm), X-ray (1 nm), e beam (30 and 50 keV), and He+ ions is evaluated

Nineteen chemically amplified ultrathin resists were imaged using exposure to extreme-ultraviolet ͑EUV͒ ͑13.4 nm͒ and deep-ultraviolet ͑DUV͒ ͑248 nm͒ radiation. Direct comparisons were made of photospeed, resolution, and line edge roughness ͑LER͒. The photospeed of these resists at 248 nm shows a good correlation with photospeed at EUV for three polymer types, but appears independent of photoacid generator type. This result underscores the importance of the polymer in photoacid generation at EUV. Resolution showed poor correlation between DUV and EUV. Correlations were made between the line edge roughness of EUV-imaged features and unexposed film thickness loss, resist contrast, image log slope ͑ILS͒, and LER of resists exposed at DUV. Both contrast and image log slope play important roles in defining LER performance-where the best LER is achieved at high contrast and high ILS.

The relationships between polymer molecular weight, surface roughness measured by Atomic Force Microscopy (AFM), and EUV (Extreme UltraViolet, 13.4 nm) line edge roughness (LER), were studied in four separate rounds of experiments. In Round 1 , EUV-2D (XP98248B) was prepared with seven levels of added base. These seven resists were patterned using EUV lithography; the LER was determined using 100 nm dense lines. The LER of the seven resists dramatically decreases with increasing level of base. These LER results were compared with the surface roughness of these resists after development for unexposed and DUV (248 nm) exposed surfaces. In Rounds 2-4, we evaluated three sets of EUV-2D type resists prepared with polymers having M of 2.9, 4.9, 6. 1, 9.1, 16. 1, and 33.5 Kg/mole. EUV LER and surface roughness were determined for each resist. In Round 2, the polymers were substituted into the EUV-2D resist matrix with no other formulation changes. In Round 3, the PAG level was decreased with increasing polymer M to obtain a constant unexposed film thickness loss (UFTL) for all six resists. In Round 4, both PAG level and base level were modified to yield six resists with similar sensitivity and UFTL. These experiments have led to conclusions about the impact of polymer molecular weight on imaging LER and AFM surface roughness, as well as elucidating the relationship between all three.

New acetal or ketal blocking reagents were investigated for use in e-beam lithography and compared with the performance of ethyl vinyl ether (EVE). Three blocking groups, a-Angelicalactone (AL), 6-methylene-5,6-benzo-l,4-dioxane (MBD), and MANA50 (an undisclosed blocking group) were reacted with polyp-hydroxystyrene) (PHS) under acid catalyzed conditions to form AL-PHS, MBD-PHS, MANA50-PHS. The performance objectives pursued in the design of these new materials was to use acetal (ketal) chemistry to deliver wide process latitudes (e.g. good PED performance and minimal PEB sensitivity), use high molecular weight blocking groups to eliminate outgassing, and use the novel concept of multiple anions to deliver lithographic performance. These new materials are called Multiple Anion Nonvolatile Acetal (MANA) resists. Resists films were exposed with 50 kV electrons, post exposure baked (PEB), and developed with 0.26 N TMAH. Resists prepared with the third blocking group, MANA50, gave imaging performance independent of PEB humidity and were relatively insensitive to PEB temperature and post-exposure delay (PED). These resists gave the best resolution (90 nm) and profiles of all the materials tested, as well as showing very low outgassing and good etch resistance.