TiNx as a new embedded material for attenuated phase shift mask

Abstract

In this paper TiNx (x > 1.3) as a new material suitable for using as an embedded layer for an attenuated phase shift mask (APSM) is presented. TiNx thin film was formed by plasma sputtering under a gas mixture of Ar and N-2 (40:2 sccm). The related characteristics of TiNx at 365 nn (i-line) wavelength are as follows: n (refractive index) similar to 3.07; k (absorbance coefficient) similar to 0.531; R (reflectivity) 27 similar to 30%; rho (resistivity) similar to 52 mu Omega-cm (132 nm on quartz). For required phase shift degree theta=180 degrees, calculated thickness d of TiNx film is 88.2 nn, and transmittance T under 365 nm wavelength at this thickness is 14.5 % which is within the useful range for APSM. TiNx film also has good electrical conductivity, suitable for e-beam direct-write in patterning mask.