Line edge roughness after development in a positive-tone chemically amplified resist of post-optical lithography investigated by Monte Carlo simulation and a dissolution model

Line edge roughness (LER) of patterned features in chemically amplified (CA) resists is formed in the acid generation stage and expected to be moderated by the acid diffusion and development process. It is essential to obtain information on the limit of LER in order to realize next-generation lithographies such as electron beam or extreme ultraviolet. Here, we report for the first time a process simulator based on physical and chemical reaction mechanisms. The LER of a positive-tone CA resist after development is investigated by Monte Carlo simulation and Mack's dissolution model. We found that the LER (high frequency) of less than 1.2?nm is achievable, although the process conditions and material design for achieving such a small LER are strict.     

Structural and optical characterization of self-formed GaP/InP quantum dots

By growing (GaP)_1.5(InP)_1.88 and (InP)_1.88(GaP)_1.5 short-period superlattices (the former material is the first layer on the GaAs (311) substrate) by gas source MBE, composition-modulated quantum dots were self-formed in both cases. The dot size is about 20 nm in GaP/InP and 22 nm in InP/GaP sample. The photoluminescence energy is higher for the GaP/InP sample, corresponding to the difference in the dot size. The photoluminescence decay time of the InP/GaP sample is less dependent on the emission wavelength and temperature than that of the GaP/InP sample.     

Preparation and properties of glycerol-based double- or triple-chain surfactants with two hydrophilic ionic groups

A novel series of glycerol-based double- or triple-chain surfactants with two sulfonate, two sulfate or two carboxylate groups was conveniently prepared by reactions of 1-O-alkylglycerol diglycidyl ethers with long-chain fatty alcohols, and followed by reactions with propanesultone, chlorosulfonic acid or bromoacetic acid, respectively. The sulfate and carboxylate types of compounds have higher water solubilities than the corresponding sulfonate type of compound bearing the same lipophilic group. The triple-chain surfactants show excellent surface-active properties, such as micelle forming and ability to lower surface tension, compared not only with the corresponding single-chain anionic surfactants, but also with the corresponding double-chain surfactants. The effect of the difference in head groups of these compounds on surface-active properties is described. Foaming properties, wetting ability and lime-soap dispersing requirement are also discussed.     

Thermal Expansion of YBa2Cu3O7_xas Determined by High-Temperature X-ray Diffraction under Controlled Oxygen Partial Pressures

The high-temperature phase relationship and thermal expansion coefficient of YBa₂Cu₃O_7-x under constant oxygen nonstoichiometry, x, were determined by high-temperature powder X-ray diffraction analysis under controlled oxygen partial pressure at temperatures up to 800^deg;C. The results are discussed based on reported nonstoichiometry data. The present study showed an orthorhombic-to-tetragonal transition near the composition x = 0.5. The lattice parameter c, perpendicular to the Cu-O plane, showed a maximum at around x = 0.7 to 0.8. In the ortho-rhombic phase, the lattice parameters a and b along the Cu-O plane were essentially constant for x < 0.2. For 0.2 < x < ∼ 0.5, a increased and b decreased with x. In the tetragonal phase, with x < ∼ 0.5, the lattice parameter a decreased with x. The thermal expansion coefficient, α, along the c-axis ranged from 19 × 10^-6 to 25 × 10^-6-K^-1, whereas a along the a- and b-axes ranged from 12 × 10^-6 to 22 × 10^-6-K^-1 at 400° to 800^deg;C, and these values were very small below 400^deg;C. It was found that a, b, and α along the a- and b-axes are smaller when the oxygen content along the respective axes is less, while the area of the ab plane and its thermal expansion coefficient are larger when the deviation of the oxygen content from the stoichiometric compositions of YBa₂Cu₃O₇ or YBa₂Cu₃O₆ is larger. Changes of x and temperature affected c more strongly than a and b.     

CO2 reforming of waste plastics

Carbon dioxide reforming of polyethylene was carried out. Pyrolysis and catalytic carbon dioxide reforming were combined. Polyethylene was packed at the bottom of the reactor and the catalyst, Pd/Al₂O₃, was packed at the top of the reactor. The pyrolysis of the polyethylene occurred at the bottom of the reactor, and the pyrolysis products reacted with carbon dioxide on the catalyst bed. Carbon dioxide reforming occurred on the catalyst bed zone. Hydrogen, carbon monoxide, methane, ethane, ethene were produced at 910 and 720 K which were the catalyst and polyethylene temperature, respectively. Polyethylene was completely reformed to carbon monoxide and hydrogen when catalyst temperature was increased or polyethylene temperature was decreased.     

Mitochondrial Unfolded Protein Responses in White Adipose Tissue: Lipoatrophy,Whole-Body Metabolism and Lifespan

The mitochondrial unfolded protein response (UPR^mt) is a stress response mediated by the expression of genes such as chaperones, proteases, and mitokines to maintain mitochondrial proteostasis. Certain genetically modified mice, which defect mitochondrial proteins specifically in adipocytes, developed atrophy of the white adipose tissue, resisted diet-induced obesity, and had altered whole-body metabolism. UPR^mt, which has beneficial functions for living organisms, is termed “mitohormesis”, but its specific characteristics and detailed regulatory mechanism have not been elucidated to date. In this review, we discuss the function of UPR^mt in adipose atrophy (lipoatrophy), whole-body metabolism, and lifespan based on the concept of mitohormesis.     

Sequential Reaction-Separation in a Microchannel Reactor for Liquid–Liquid Phase Transfer Catalysis

A microchannel reactor with guideline structure was investigated to carry out sequential reaction- separation. The catalytic reaction between benzyl chloride and sodium sulfide was demonstrated. Under parallel multiphase flow conditions, the catalytic reaction proceeded with phase separation could be ensured. The phase separation performance was enhanced by performing surface modification.     

Experimental Investigation of Local Temperature Increase in Disk Surfaces of Hard Disk Drives Due to Laser Heating During Thermally Assisted Magnetic Recording

In this study, a novel method was developed to evaluate the local temperature increase under steady-state conditions on disk surfaces of hard disk drives due to laser heating during thermally assisted magnetic recording (TAMR). In particular, we evaluated changes in the refractive index and the extinction coefficient of disk substrates due to laser heating by varying the laser power, and determined the relationship between the laser power and the changes in these optical constants. Simultaneously, test disks were heated using a conventional heater, under heating conditions equivalent to those associated with laser heating, by varying the temperature. We evaluated the changes in the optical characteristics of the disk substrates due to heating, and formulated a relationship between the temperature and the changes in the optical characteristics. Then, the local temperature increase due to laser heating under steady-state conditions was evaluated by calibrating both sets of experimental results. In addition, the temperature increase was compared with the numerical simulation results, and good agreement was observed between the experimental and the simulation results. Thus, it was confirmed that, this method is useful and effective for estimating the temperature increase under steady-state conditions in disk surfaces of hard disk drives due to laser heating during TAMR. This method is also a first step toward understanding the occurrence of temperature phenomena in TAMR systems.     

Direct Evaluation of Gate Line Edge Roughness Impact on Extension Profiles in Sub-50-nm n-MOSFETs

In this paper, the impact of gate line edge roughness (LER) on two-dimensional carrier profiles in sub-50-nm n-MOSFETs was directly evaluated. Using scanning tunneling microscopy (STM), it was clearly observed that the roughness of extension edges induced by gate LER strongly depended on the implanted dose, pockets, and coimplantations. Impurity diffusion suppressed by a nitrogen (N) coimplant enhanced the roughness of the extension edges, which caused fluctuations in the device performance. The expected effect based on the carrier profiles measured by STM of the N coimplant on the electrical performance of the n-MOSFETs was verified