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Fluorinated silicon nitride thin film as a bottom antireflective layer (BARL) material, being suitable for line-patterning in 0.25 _m KrF excimer laser (248 nm) lithography, has been studied by film fabrication/characterization and computer simulation. Three-dimensional reflectance simulation process suggests that the 0% reflectance between photoresist (PR) and BARL can be achieved by selecting proper combinations of film optical properties such as refractive index (n), extinction coefficient (k ) and thickness (d ). For the PR/300 °A BARL/c-Si or PR/300 °A BARL/W-Si structure at a wavelength of 248 nm, the simulation process reveals that nearly 0% reflectance could be obtained when the n and k values of the film are 2.109 and 0.68 or 2.052 and 0.592 respectively. The fluorinated silicon nitride films prepared by ICP enhanced CVD have been evaluated with the variations of NF3 flow rates under the two conditions of SiH4:N2 = 2 : 15 and 3:20 (sccm). The film n and k values at 248 nm vary in the ranges of 1.665–2.352 and 0.007–0.695 respectively, depending on gas flow ratio. As it is very sensitive to the film thickness, the reflectance could be reduced, using compoter simulation, to almost 0% by changing the film thickness. Furthermore, the ARL performance for 0.25 _m line/space processed by the KrF excimer laser stepper and the stripping ability/selectivity show this material to be a superior candidate for deep-UV microlithography applications.

Titanium oxide thin film, fabricated with tetraisopropyltitanate and oxygen by electron cyclotron resonance–plasma-enhanced chemical vapor deposition, is investigated as a potential candidate for the antireflective layer in KrF excimer laser (248-nm) lithography. The oxygen flow-rate dependence of the optical properties such as the refractive index (n) and the extinction coefficient (k) of the film at the 248-nm wavelength has been characterized, and the films with the expected combinations of n and k values for the antireflective layer have been deposited. Simulation results indicate that reflectance values of less than 4% and as low as 1.2% can be reached at the interface between the photoresist and the film postulating the structures of the photoresist/300-Å TiOx film/c-Si substrate and the W-Si substrate, respectively, by selected proper combinations of n and k values. Moreover the reflectance can be further reduced to almost zero by changing the film thickness. Thus it is found that titanium oxide thin films can be used as the bottom antireflective layer in KrF excimer laser lithography.

The investigation of single layer halftone phase shift mask (SLHTPSM) has been carried by both simulation and chromium fluoride film fabrication. Theoretical analysis provides the optimum SLHTPSM constructions for I-line (365 nm), KrF (248 nm) and ArF (193 nm) microlithographies. A fully characterization of chromium fluoride film processed by de magnetron sputtering shows a feasibility of using this film in the fabricating DUV-PSM.

Chromium oxide films were deposited using DC reactive magnetron sputtering system with different gasring positions. It was found that the film quality was improved, while film thickness deviation over 2′' area of silica wafer increased, as the distance between the target and the gasring increased. To improve both the film quality and the thickness uniformity, a method of mesh insertion was tried and verified to meet the purpose. Introduction of mesh produced stable plasma and resulted in more uniform and smooth planar film without any contamination from the mesh. These phenomena were explained in terms of gettering and scattering effects of the mesh.

An optical simulation for a single-layer halftone phaseshifting mask (SLHTPSM) has been established and verified by the experimental data from several different sources. This simulation is suitable for a wide lithography exposure wavelength; for example, i-line, KrF and ArF etc. Theoretical analyses give some important tendencies of the optical parameters such as refractive index, extinction coefficient and film thickness. The optimum SLHTPSM structures for KrF (248 nm) have been derived by the simulation processes, which include the optimized combinations of extinction coefficient/refractive index and film thickness/refractive index achieved to deliver the 5%, 10% and 20% transmittance and 180 degrees phaseshifting. The simulation shows the film refractive index to be in the region of 1.7 - 3. The simulation program also provides guidance for the SLHTPSM fabrications.

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