Photosensitivity and line-edge roughness of novel polymer-bound PAG photoresists

Abstract

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.

Effect of Orientation on Plasmonic Coupling between Gold Nanorods

“…The substrates used to support the nanoprisms were prefabricated freestanding silicon nitride membranes whose fabrication has been described in detail elsewhere. 34 Briefly, silicon wafers with a ͗100͘ orientation were purchased from University Wafer and cleaned and placed in a Tystar Furnace. Si 3 N 4 was deposited onto the wafer surface using a low-pressure chemical vapor deposition process at a deposition rate of 5 nm/min to a final thickness of 50 Ϯ 3 nm.…”

“…Nanorod arrays were fabricated using a JEOL JBX-9300FS 100 kV electron beam lithography (EBL) system. The substrates used to support the nanoprisms were prefabricated free-standing silicon nitride membranes whose fabrication has been described in detail elsewhere . Briefly, silicon wafers with a ⟨100⟩ orientation were purchased from University Wafer and cleaned and placed in a Tystar Furnace.…”

Pronounced Effects of Anisotropy on Plasmonic Properties of Nanorings Fabricated by Electron Beam Lithography

“…Nanoring arrays were fabricated using a JEOL JBX-9300FS 100 kV electron beam lithography (EBL) system. The substrate upon which the nanorings were supported was an array of free-standing silicon nitride (Si 3 N 4 ) membrane windows, whose fabrication has been described elsewhere . Each Si 3 N 4 membrane window measured 150 × 150 μm 2 and was used for a single design pattern, which measured 200 × 200 μm 2 to ensure overlap with the window.…”

Resist fundamentals for resolution, LER, and sensitivity (RLS) performance tradeoffs and their relation to micro-bridging defects

“…The system integration of the optical elements drives a small loss in optical contrast, but a larger loss in contrast is driven by acid diffusion in the resist. Resist suppliers continue to make good progress on the reduction of acid diffusion through the use of large PAG ions that restrict mobility 7 , base quencher that consumes mobile acid in unexposed areas 8 and new innovations like polymer bound PAG systems 9 . However, some methods of acid diffusion control like base quencher can hurt sensitivity, which highlights the challenge of balancing RLS performance.…”

“…At KrF and ArF exposure wavelengths, an increase in the absorbance of the film through PAG loading is typically used to increase sensitivity. At EUVL exposure wavelengths, sensitivity increases are more complicated due to the relative transparency of materials at 13.5 nm as well as the dependence on secondary electrons for actual energy transfer 9 . The general strategy has been to incorporate sensitizers in the resist to capture secondary electron energy or use very high PAG loadings to effectively increase the quantum efficiency [11][12] .…”