AlSi xN y (x∼0.31, y∼0.45) thin film as a new embedded material for AttPSM in 193 nm lithography was presented. With the good controlling of plasma sputtering of Al (100∼130 W) and Si (20∼50 W) under Ar (75 sccm), and nitrogen (2.5∼5 sccm), AlSi xN y has enough deposition latitude to meet the requirements as an embedded layer. For required phase shift 180 degree, the calculated thickness d 180 of AlSi xN y films is in the range of 87∼100 nm. The T% in 365 and 488 nm for optical inspection and alignment is below 40%. Its sheet resistance R s, is less than 0.8 kΩ/square. Helicon wave plasma etcher and Taguchi design of experiment have been applied to the study of the etching selectivity of AlSi xN y over substrate fused silica and negative resist NEB-22. Under chamber pressure 3 mtorr, BCl 3 45 sccm, Cl 2 7 sccm, plasma source power 1400 W and substrate bias RF power 30 W for the selectivity of AlSi xN y over NEB-22 was found to be 4.8:1. The selectivity of AlSi xN y over fused silica was 12.3:1 under chamber pressure 9 mtorr, BCl 3 13 sccm, Cl 2 45 sccm, O 2 8 sccm, plasma source power 1400 W and substrate bias RF power 30 W. A 0.3 μm line/space etched pattern using AlSi xN y as embedded layer was successfully fabricated.