Compositional optimization of glass forming alloys based on critical dimension by using artificial neural network

An artificial neural network （ANN） model was developed for simulating and predicting critical dimension dc of glass forming alloys. A group of Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were designed based on the dc and their de values were predicted by the ANN model. Zr-Al-Ni-Cu and Cu-Zr-Ti-Ni bulk metallic glasses were prepared by injecting into copper mold. The amorphous structures and the determination of the dc of as-cast alloys were ascertained using X-ray diffraction. The results show that the predicted de values of glass forming alloys are in agreement with the corresponding experimental values. Thus the developed ANN model is reliable and adequate for designing the composition and predicting the de of glass forming alloy.

Optimum design of photoresist thickness for 90-nm critical dimension based on ArF laser lithography

In this work, a 90-nm critical dimension （CD） technological process in an ArF laser lithography system is simulated, and the swing curves of the CD linewidth changing with photoresist thickness are obtained in the absence and presence of bottom antireflection coating （BARC）. By analysing the simulation result, it can be found that in the absence of BARC the CD swing curve effect is much bigger than that in the presence of BARC. So, the BARC should be needed for the 90-nm CD manufacture. The optimum resist thickness for 90-nm CD in the presence of BARC is obtained, and the optimizing process in this work can be used for reference in practice.

Critical Dimension for Stable Self-Gravitating Stars in AdS

We study the self-gravitating stars with a linear equation of state, P = aρ, in AdS space, where a is a constant parameter. There exists a critical dimension, beyond which the stars are always stable with any central energy density; below which there exists a maximal mass configuration for a certain central energy density and when the central energy density continues to increase, the configuration becomes unstable. We find that the critical dimension depends on the parameter a, it runs from d = 11.1429 to 10.1291 as a varies from a = 0 to 1. The lowest integer dimension for a dynamically stable self-gravitating configuration should be d = 12 for any a E [0, 1] rather than d = 11, the latter is the case of self-gravitating radiation configurations in AdS space.

Replication of large area nanoimprint stamp with small critical dimension loss

In this paper,the replication process of large area nanoimprint stamp with small critical dimension(CD) loss was investigated,using the thin residual layer nanoimprint lithography(NIL) technology.The residual layer thickness was optimized by changing the spin-coated resist thickness.The dependences of the residual layer etching rate on gas flow,chamber pressure,and RF power were investigated,and the optimized process conditions were established.By means of the thin residual layer NIL technique and optimized residual layer etching process,large area stamp with small CD loss and multi-orientation patterns was successfully replicated on 2-inch SiO2/Si wafer.The CD loss was controlled within 5 nm.The replicated stamp showed high performance in the patterning with thermal NIL.The replication process reported in this work could also be used to fabricate large area nanostructures with small CD loss.

Preliminary Research on Critical Dimension of Wood under Vacuum Drying

The objective of this experiment is to explore how the thickness and the length of the specimen affect the vacuum drying rate, and to explore whether the different lengths of specimens have different vacuum drying rates. The results are as follows: in a certain range of dimension and pressure, the length of specimens has more effect on the vacuum drying rate than the thickness. When the ratio of end area to volume is less than 0.10 cm-1, the drying rate decreases exponentially with the increasing of the length.

FRACTAL DIMENSION OF TIME SERIES APPLIED TO IDENTIFICATION OF CRITICAL SPEED OF JEFFCOTT ROTOR SYSTEM

The dynamical behaviors of logistic map（May＇s model） and duffing equation are studied through fractal dimension of time series at different parameters. It is shown that the parameters of dynamical behaviors can be identified effectively by the curve of fractal dimension with parameter increments. For further verification, the relation between the fractional dimension of time series and rotational speed can be used to identify critical speed effectively by using this method to a plate Jeffoctt rotor system. The numerical and experimental result indicates that the identification of critical parameters is effective.

Characterization of a nano line width reference material based on metrological scanning electron microscope

The line width(often synonymously used for critical dimension,CD)is a crucial parameter in integrated circuits.To accurately control CD values in manufacturing,a reasonable CD reference material is required to calibrate the corresponding instruments.We develop a new reference material with nominal CDs of 160 nm,80 nm,and 40 nm.The line features are investigated based on the metrological scanning electron microscope which is developed by the National Institute of Metrology(NIM)in China.Also,we propose a new characterization method for the precise measurement of CD values.After filtering and leveling the intensity profiles,the line features are characterized by the combination model of the Gaussian and Lorentz functions.The left and right edges of CD are automatically extracted with the profile decomposition and k-means algorithm.Then the width of the two edges at the half intensity position is regarded as the standard CD value.Finally,the measurement results are evaluated in terms of the sample,instrument,algorithm,and repeatability.The experiments indicate efficiency of the proposed method which can be easily applied in practice to accurately characterize CDs.

Nonlinear Biharmonic Equations with Critical Potential

In this paper, we study two semilinear singular biharmonic equations： one with subcritical exponent and critical potential, another with sub-critical potential and critical exponent. By Pohozaev identity for singular solution, we prove there is no nontrivial solution for equations with critical exponent and critical potential. And by using the concentrate compactness principle and Mountain Pass theorem, respectively, we get two existence results for the two problems. Meanwhile, we have compared the changes of the critical dimensions in singular and non-singular cases, and we get an interesting result.

Comparison of EUV Photomask Metrology Between CD-AFM and TEM

Accurate metrology of extreme ultraviolet (EUV) photomask is a crucial task. In this paper, two different methods for reference EUV photomask metrology are compared. One is the critical dimension atomic force microscopy (CD-AFM). In the measurements, the contribution of its AFM tip geometry is usually the dominant error source, as measured AFM images are the dilated results of measured structures by the AFM tip geometry. To solve this problem, a bottom-up approach has been applied in calibrating the (effective) AFM tip geometry where the result is traceably calibrated to the lattice constant of silicon crystals. The other is transmission electron microscopy (TEM). For achieving measurement traceability, structure features are measured in pairs in TEM images;thus the distance between the structure pair calibrated by a metrological AFM in prior can be applied to determine the magnification of the TEM image. In this study, selected photomask structures are calibrated by the CD-AFM, and then sample prepared and measured by high-resolution TEM nearly at the same location. The results are then compared. Of six feature groups compared, the results agree well within the measurement uncertainty, indicating excellent performance of the developed methodology. This research supports the development of a photomask standard, which is applied as a “reference ruler” with improved low measurement uncertainty in photomask fabs.

Large number of bubble solutions for the equation ?u + K(y)u^((N+2)/(N- 2)± ε)= 0 on R^N

This paper concerns the following nonlinear elliptic equation:{?u + K(y)u^((N+2)/(N-2)±ε)= 0, u > 0, y ∈ R^N,u ∈ D^(1,2)(R^N),where ε > 0, N≥5, K(y) is positive and radially symmetric. We show that, under some local conditions on K(y), this problem has large number of bubble solutions if ε is small enough. Moreover, for each m ∈ [2, N- 2),there exists solutions whose functional energy is in the order of ε^(-(N-2-m)/((N-2)~2)).