Showing papers by "Igor Luzinov published in 2005"

Synthesis of high-density grafted polymer layers with thickness and grafting density gradients.

Abstract: A novel approach was developed for the synthesis of tethered polymer layers with thickness and grafting density gradients. Poly(glycidyl methacrylate) (PGMA) was employed as a primary anchoring layer to attach the polymer chains to the surface of a silicon wafer. A linear temperature gradient heated stage was used for the generation of a gradual variation in the thickness of the anchoring PGMA film along the substrate. The obtained gradient was translated into the polymerization initiator gradient via the reaction between the epoxy groups of PGMA and the carboxyl functionality of 2-bromo-2-methylpropionic acid (BPA). The attachment of BPA to the surface modified with the monolayer of PGMA was confirmed by X-ray photoelectron spectroscopy experiments. To complete the experimental procedures, surface-initiated atom transfer radical polymerization was performed to synthesize the grafted polymer layers with thickness and surface densities that were varied along the substrate. The grafting density of the sampl...

Low‐Temperature Growth of Thick Polystyrene Brushes via ATRP

Abstract: Summary: This contribution describes the graft polymerization of polystyrene (PS) by atom transfer radical polymerization at 50, 60, and 75 °C. Thick PS brushes were grown from initiator-functionalized PGMA layers on silicon, and constant growth rates provide indirect evidence that the polymerizations were controlled. Formation of polystyrene brushes at T < Tg by ATRP of styrene from α-bromoester initiator-functionalized poly(glycidyl methacrylate) layers.

Nanocomposite liquids for 193 nm immersion lithography: a progress report

Abstract: Immersion lithography is a new promising approach capable of further increasing the resolution of semiconductor devices. This technology requires the development of new immersion media that satisfy the following conditions: the media should have high refractive index, be transparent and photochemically stable in DUV spectral range. They should also be inert towards photoresists and optics and be liquid to permit rapid scanning. Here we propose and explore a novel strategy in which high refractive index medium is made of small solid particles suspended in liquid phases (nanocomposite liquids). The dielectric particles have high refractive index and the refractive index of nanocomposite liquids becomes volume weighted average between refractive indices of nanoparticles and the liquid phase. We investigate aluminum oxide (alumina) nanoparticles suspended in water. Alumina is known to have high (1.95) refractive index and low absorption coefficient at 193 nm. Alumina nanoparticles were prepared by chemical methods followed by removal of organic molecules left after hydrolysis reactions. Measurements of optical and reological properties of the nanocomposite liquid demonstrated potential advantage of this approach for 193 nm immersion lithography.

Gradient stimuli-responsive polymer grafted layers

Abstract: We discuss our recent results on fabrication and study of responsive thin polymer films covalently grafted to solid substrates. The films are prepared from two different incompatible polymers (mixed polymer brush), where the film composition gradually changes along a one direction of the sample surface. The gradual change of the composition causes the gradual change of wetting behavior. At the same time incompatibility of the polymers introduces the switching behavior due to the phase segregation mechanisms. The switching is sensitive to external signals (solvent, temperature, pH). Overlap of these two phenomena allows us to design surfaces with switchable gradients of wetting.

AFM Measurements of Adhesion between Actual CMP Slurry Particles and Various Substrates

Abstract: One of the critical parameters in chemical mechanical polishing (CMP) technology is adhesion between abrasive particles and surfaces being polished. Accumulated up to date theoretical and experimental facts insist that development of advanced material removal and cleaning methods requires understanding and evaluation of particle adhesion in these processes. To this end, our research focuses on AFM studies of interaction between the slurry particles and different substrates treated by CMP processes. To conduct adhesion measurements, the particles present in a CMP system and model latex particle were first attached to the surface of silicon wafer covered with monolayer of polymer(s) having high affinity to particles and the silicon wafer. Glass/quartz sphere (10-60 microns) was attached to AFM cantilever with appropriate spring constant. (The sphere represented the surface of material being polished and might be covered with various materials during future investigations.) Next, AFM force volume mode, which utilizes the collection of the force-distance curves over selected surface areas, was used for the adhesion measurements.