Dynamics of Directed Self-Assembly of PS-b-PMMA during Solvent Annealing

The graphoepitaxy of symmetric PS-b-PMMA BCP film on the PS 60 mol% brush layer is carried out using the chemically homogeneous topological pattern of SiO2 layer and the home-made solvent annealing tool. It is confirmed by atomic force microscopy that PS-b-PMMA film on the periphery of the trench flows into the trench during the solvent annealing, so that the film thickness in the trench is thicker than that on the un-patterned area. The solvent annealing time dependence indicates the lamellar orientation in the trench changes from a mixture of the lamellar domain parallel and perpendicular to the side walls to the lamellar domain parallel to the side walls, and then changes back to the mixture, although the lamellar orientation perpendicular to the substrate remains the same. This result is also discussed with a free energy model for confined di-block copolymer. The lamellar domain parallel to the side walls indicates that the surface tensions of PS and PMMA blocks absorbing solvent vapor with the PS 60 mol% brush layer are not the same during the solvent annealing at 55 °C. Furthermore, the free energy difference between the parallel and perpendicular orientations is supposed to fluctuate due to the dynamics of PS-b-PMMA molecules by the solvent annealing, so that the lamellar orientation results in either of the lamellar domain parallel, perpendicular, or the mixture

Directed Self-Assembly of Block Copolymer, No1

The PS-rich and neutral PS-b-PMMA block copolymer (BCP) films were spin coated on the neutral random copolymer hydroxyl-terminated PS-r-PMMA layers grafted on the native oxide and 50 nm thick PECVD amorphous silicon oxide layers. Relationship between the grafting density of BCP and surface density of hydroxyl moiety on silicon oxide is discussed. Furthermore, optimization of annealing BCP films is reported, and wetted and de-wetted BCP films are shown in optical microscope images. In addition, finger print and nanopore structures of BCP films are also indicated in SEM images

Thin Dry Silicon Oxide Films Grown by Thermal Oxidation

Dry thermal oxidation is performed at 900, 950, 1000, and 1050 C in fused silica tube furnace (Sandvik) for 10, 20, 50, 100 and 200 min. The results are analyzed by both of Deal-Grove model and the method of Gerlach, Maser, and Saad. In the analysis using the Deal-Grove model, the parabolic rate constants are obtained to be 2.1, 7.0, 17.5, and 42.4 nm^2/min at 900, 950, 1000, and 1050 C, respectively, and the linear rate constants are acquired to be 0.2, 0.4, 0.8, and 1.2 nm/min at 900, 950, 1000, 1050 C, respectively. Activation energies of the parabolic rate constant and the linear rate constant are obtained to be 2.67 and 1.55 eV, respectively. In the analysis using the method of Gerlach, Maser, and Saad, the activation energy of the oxide growth rate for the 5 nm thick oxide is obtained to be 2.49 eV, whereas that for the 40 nm thick oxide to be 1.93 eV. The film uniformity for 30 nm thickness shows more than 10%, while that for the thickness of more than 50 nm indicates less than 5%, suggesting that measurement on 30 nm thick film using Filmetrics F50 is not still accurate enough. Standard deviation and coefficient of variation are also examined to discuss the film uniformity

Progress Report III: Fabrication of Nanopores in Silicon Nitride Membranes using Electron-beam Lithography

This report describes the fabrication of a long-range orderly nanopore structure in free-standing siliconnitride membranes using electron-beam lithography (EBL). The parameter setting and challenges of eachstep are discussed

Stress in Silicon Oxide Thin Films Grown by Dry Thermal Oxidation

Dry thermal oxidation is performed at 900, 950, 1000, and 1050 C in fused silica tube furnace (Sandvik)for 10, 20, 50, 100 and 200 min. The properties of the thin-films such as refractive index and stress arestudied in this paper. Refractive indexes of the thin-films are obtained using ellipsometer and decreasesfrom 1.78 to 1.46 as the film thickness increases.Stress of the thin-films is theoretically calculated,experimentally measured and then compared.Stress is calculated theoretically using Stoney’s stressequation and Goklaney’s stress equations. Stress is measured experimentally using the profilometer. Ex-perimentally measured stress and refractive indexes are then compared to discuss the density of the thin-films

Fabrication of High Aspect Ratio Nanopillars using Metal Assisted Chemical Etching

This report describes fabrication of 100 to 200 nm diameter silicon nanopillars with ~140:1 aspect ratio using Metal Assisted Chemical Etching (MacEtch) process giving a high etch rate of ~930 nm/min, and also discusses an area dependence of the etch uniformity and rate, using 0.5 and 1 µm diameter, and 2 mm x 2 mm Au films. It is found that the etching using the Au film with the area of 0.2 µm2 is uniform, but that with the area of more than 0.8 µm2 is not, suggesting that the diffusion length of the species in MacEtch reaction underneath the Au film is ~300 nm

Activation and isolation of mitochondrial adenosine triphosphatase by ultrasonic irradiation

With the purpose to clarified the mode of localization and mechanisms of activation of ATPase in the mitochondrial membrane, analyses were made on the properties of mitochondrial ATPase from the structural and functional aspects. The activation of ATPase by DNP and Mg++ and the oligomycin sensitivity were investigated in a series of inner membrane fragment samples obtained by ultrasonic irradiation and those samples obtained in the processes of isolation and purification of ATPase from rat liver mitochondria and beef heart mitochondria in parallel with electron microscope observations. As a result it has been found that the membrane fragments obtained from rat liver and beef heart mitochondria by ultrasonication exhibited high respiratory activity and unmasked ATPase activity which was charac· terized by remarkable stimulation by Mg++ and inhibition by oligomycin and azide. Therefore, mitochondrial ATPase seems to be bound fairly closely to the inner mitochondrial membrane. In the membrane fragments prepared by ultrasonication of intact mitochondria, ATPase activity was stimulated by DNP, but in the supernatant fractions was not. On the other hand, the supernatant fraction obtained from BHM and inner membrane fragments by severe sonication exhibits a marked ATPase activity and the activity incresed in each step of the purification on the treatments with acid, protamine and heat. Especially in the case of membrane fragments the protamine treatment can be omitted. Electron microscope observation of the fractions in each step of the purification proved the head pieces to be ATPase. The ATPase activity of solubilized head pieces is insensitive to oligo. mycin and coincides with the soluble ATPase of PULLMAN etat. (8) in the points of its cold labile property and optimum pH, but it shown no accele. ration of ATPase activity by DNP.</p