The invention provides a backside phase grating mask and method for manufacturing the same. The mask includes mask patterns formed over a frontside of a substrate and a phase grating formed over a backside of the substrate. The mask patterns correspond to a layout of diagonal patterns extending in a direction rotated toward a predetermined direction from an axis of a rectangular coordinate system. The phase grating extends in a direction parallel to the extending direction of the mask patterns. The phase grating includes first and second phase regions alternately arranged over the backside ofthe substrate with a phase difference of 180 DEG therebetween. The first and second phase regions induce a phase interference that blocks a zero-order light of an exposure light incident to the substrate and allows a primary light to be incident to the mask patterns.