An accurate method for measuring defocus, which is an application of phase shifting mask technology for higher resolution microlithography, reveals the impacts of reticle topography on optical microlithography. On the topographic reticles, there exist many focus monitors besides overlay marks. These reticles include almost flat and convex to concave topography with a maximum altitude difference of 2 m. Contrary to our expectation, the experimental results showed that reticle topography has little impact on the field curvature, but has a significant impact on overlay errors. The lithography tool used in this experiment presses topographic reticles flatly against the face of a reticle stage to plane the field curvature, with generating magnification errors only in the slit direction.

The applications of a high-transmittance embedded layer (HTEL) (T ¼ 15 { 35%) in an attenuated phase-shifting mask were studied by simulation with the aid of Taguchi design of experiment. A modified transmittance control mask with HTEL was proven to be useful in preventing photoresist bridging between two adjacent contact holes on a wafer. The optimal trnasmittance (T) was determined to be 30 -35%. With optimization, the optimized results of the fabrication of a 45 nm isolated line using a 193 nm wavelength light source in the immersion mode indicated that the exposure latitude (EL) increases from 1.20 to 1.31 mJ/cm 2 with the following settings: HTEL T of 35%, annular off-axis illumination (OAI) outer of 0.7, inner of 0.4, and numerical aperture (NA) of 1.152. For the optimization of the fabrication of 70 nm iso-dense lines, the simulation results showed that EL increases from 2.21 to 2.30 mJ/cm 2 with the following settings: HTEL T of 25%, dipole OAI center of 0.6, radius of 0.2, and NA of 1.224.

The monomer-dimer self-association equilibrium of 2,2-dimethyl-3-ethyl-3pentanol in n-octane has been studied by IR spectroscopy at four temperatures (288, 298, 308, and 318 K). The solute was chosen to restrict the self-association between solute molecules to dimerization only, owing to steric hindrance of the bulky chains in the vicinity of the OH group. Two linear equations have been derived for the treatment of the experimental data. One of these equations was used to treat the data of the concentration dependent integrated absorbance of the monomer bands for each temperature to obtain the monomer molar absorptivity, e m , and dimerization constant, K. The other equation was used to treat the data of concentration-dependent dimer bands to obtain the dimer molar absorptivity, e d , and K. Thus, the dimerization constant was determined by two methods. Since the same thermodynamic quantity K is obtained from either the monomer bands or the dimer bands, the difference between them at a given temperature can serve as an assessment of the quality of the experiment. The standard enthalpy and entropy of dimerization were also obtained from a van't Hoff plot.

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Simulations for the optimization of the mask error enhancement factor (MEEF) by using Taguchi's design of experiment (DOE) method in both dry and immersion ArF lithography have been demonstrated here. By DOE, MEEF has been successfully reduced, and the process window has also been enlarged. Furthermore, in immersion lithography, MEEF has been significantly reduced, and resolution is also enhanced. In this study, we determined the optimal process and optical parameters to enlarge the process window and reduce MEEFs for different types of mask by DOE.