As the mask cost and cycle time have increased dramatically with the shrinkage in the design technology, it becomes crucial to produce photomask with lower cost and reasonable cycle time. It is also important to achieve good process window and mask quality at the same time. In this paper, we study the feasibility of DUV laser mask writing tool for sub-wavelength technology on backend layers. Comparison between DUV laser mask writing tool and 50keV electron beam writing tools was done, based on reticle critical dimension (CD) uniformity, CD through pitch and linearity performance. Besides, wafer results on CD through pitch, linearity, line end shortening, pattern fidelity are also presented. 3 sigma of reticles CD uniformity performance are around 11 to 20nm for DUV laser writer and 5 to 15nm for 50keV. CD through pitch range for reticles written using DUV laser writer are around 8 to 11nm and 3 to 5 nm for 50keV. CD linearity performance is around 10 to 20nm for DUV laser writer and 4 to 8nm for 50keV. From the results, we conclude that DUV laser writer demonstrates reasonable good mask and wafer performance, and it is adequate for sub-wavelength backend mask technology on some of the critical layers.