Evidence of speckle in extreme-UV lithography.

Based on reflective optics at 13.5 nm, extreme-UV lithography is the ultimate top-down technique to define structures below 22 nm but faces several challenges arising from the discrete nature of light and matter. Owing to the short wavelength, mask surface roughness plays a fundamental role in the increase of speckle pattern contrast, compromising the uniformity of the printed features. Herein, we have used a mask with engineered gradient surface roughness to illustrate the impact that speckle has on the resulting photoresist pattern. The speckle increases the photoresist roughness, but surprisingly, only when the mask surface roughness is well above existing manufacturing capabilities.

Patterning of tailored polycarbonate based non-chemically amplified resists using extreme ultraviolet lithography.

A series of high-performance polycarbonates have been prepared with glass-transition temperatures and decomposition temperatures that are tunable by varying the repeat-unit chemical structure. Patterning of the polymers with extreme UV lithography has been achieved by taking advantage of direct photoinduced chain scission of the polymer chains, which results in a molecular-weight based solubility switch. After selective development of the irradiated regions of the polymers, feature sizes as small as 28.6 nm have been printed and the importance of resist-developer interactions for maximizing image quality has been demonstrated.

Fluorinated acid amplifiers for EUV lithography.

Five new compounds were synthesized for use as acid amplifiers in EUV (13.5 nm) photoresists. Four compounds act as acid amplifiers and decompose by autocatalytic kinetics to generate fluorinated sulfonic acids, essential for the simultaneous improvement of resolution, sensitivity, and line edge roughness (LER) in EUV photoresists. The decomposition rates were studied using (19)F NMR in the presence and absence of 1.2 equiv of tri-tert-butylpyridine. Three acid amplifiers decomposed 490, 1360, and 1430 times faster without base than with base. Preliminary lithographic evaluations show that cis-1-methyl-2-(4-(trifluoromethyl)phenylsulfonyloxy)cyclohexyl acetate simultaneously improves the resolution, LER, and sensitivity of an EUV photoresist.

Electro-optic polymer cladding ring resonator modulators.

Compact, low capacitance optical modulators are vital for efficient, high-speed chip to chip optical interconnects. Electro-optic (EO) polymer cladding micro-ring resonator modulators have been fabricated and their performance is characterized. Optical modulators with ring diameters smaller than 50 microm have been demonstrated in a silicon nitride based waveguide system on silicon oxide with a top cladding of an electro-optic polymer. Optical modulation has been observed with clock signals up to 10 GHz.

Synthesis of neutral nickel catalysts for ethylene polymerization--the influence of ligand size on catalyst stability.

A facile synthesis of nickel salicylaldimine complexes with labile dissociating ligands is described. In addition to producing highly active ethylene polymerization catalysts, important insights into the effect of ligand size on catalyst stability and information on the mechanism of polymerization are provided.

Kinetic rates of thermal transformations and diffusion in polymer systems measured during sub-millisecond laser-induced heating.

Probing chemical reaction kinetics in the near-solid state (small molecules and polymers) is extremely challenging because of the restricted mobility of reactant species, the absence of suitable analytical probes, and most critically the limited temperature stability of the materials. By limiting temperature exposure to extremely short time frames (sub-millisecond), temperatures in excess of 800 °C can be accessed extending kinetic rate measurements many orders of magnitude. Here we demonstrate measurements on a model system, exploiting the advantages of thin-films, laser heating, and chemically amplified resists as an exquisite probe of chemical kinetic rates. Chemical reaction and acid diffusion rates were measured over 10 orders of magnitude, exposing unexpected and large changes in dynamics linked to critical mechanism shifts across temperature regimes. This new approach to the study of kinetics in near-solid state materials promises to substantially improve our understanding of processes active in a broad range of temperature-sensitive, low-mobility materials.