Mask orientation

A method of forming patterned features on a substrate comprising:

• positioning a plurality of masks over a substrate based on a mask layout, wherein
• the substrate is positioned in a first plane and the plurality of masks are positioned in a second plane when the plurality of masks are positioned according to the mask layout,
• the plurality of masks in the mask layout have edges that each extend parallel to the first plane and parallel or perpendicular to an alignment feature on the substrate,
• the substrate includes a plurality of areas configured to be patterned by energy directed through the plurality of masks arranged in the mask layout,
• the plurality of areas configured to be patterned are spaced apart from each other by one or more areas not configured to be patterned by the energy directed through the plurality of masks, and
• each area of the plurality of areas configured to be patterned is spaced apart from a closest area of the plurality of areas configured to be patterned by a shortest distance along a direction offset by at least 5 degrees from directions in the first plane that extend parallel, perpendicular, ±30 degrees, ±45 degrees, or ±60 degrees relative to the alignment feature on the substrate;
• and
• directing energy towards the plurality of areas through the plurality of masks when the plurality of masks are positioned over the substrate according to the mask layout, the directed energy forming a plurality of patterned features in each of the plurality of areas, wherein
• a number of the formed plurality of patterned features extending along directions in the first plane that are within ±2.5 degrees of being parallel, perpendicular, ±30 degrees, ±45 degrees, or ±60 degrees relative to the alignment feature are greater than a number of the formed plurality of patterned features extending along directions in the first plane that do not align within ±2.5 degrees of being parallel, perpendicular, ±30 degrees, ±45 degrees, or ±60 degrees relative to the alignment feature.

A method of forming gratings on a substrate comprising:

• positioning a plurality of masks over a substrate based on a mask layout, wherein
• the substrate is positioned in a first plane and the plurality of masks are positioned in a second plane when the plurality of masks are positioned according to the mask layout,
• the plurality of masks in the mask layout have edges that each extend parallel to the first plane and parallel or perpendicular to an alignment feature on the substrate,
• the substrate includes a plurality of areas configured to be patterned by energy directed through the plurality of masks arranged in the mask layout,
• the plurality of areas configured to be patterned are spaced apart from each other by one or more areas not configured to be patterned by the energy directed through the plurality of masks, and
• each area of the plurality of areas configured to be patterned is spaced apart from a closest area of the plurality of areas configured to be patterned by a shortest distance along a direction offset by at least 5 degrees from directions in the first plane that extend parallel or perpendicular to the alignment feature on the substrate;
• and
• directing energy towards the plurality of areas through the plurality of masks when the plurality of masks are positioned over the substrate according to the mask layout, the directed energy forming a plurality of gratings in each of the plurality of areas, wherein
• a number of the formed plurality of gratings extending along directions in the first plane that are within ±2.5 degrees of being parallel or perpendicular to the alignment feature are greater than a number of the formed plurality of gratings extending along directions in the first plane that do not align within ±2.5 degrees of being parallel or perpendicular to the alignment feature.