Patent ID: 9411223
Filing Date: 2016-08-09
CPC Classification: G03F

Claim Text:
1. A reticle comprising a focus monitor structure, said focus monitor structure comprising one or more focus monitor units, wherein each of said one or more focus monitor units comprises: a substrate; a lithographic feature region having a same transmission coefficient for electromagnetic radiation throughout; a horizontal grating region formed on a top surface of the substrate and located on a first side of said lithographic feature region; a vertical grating region formed on the top surface of the substrate and located on a second side of said lithographic feature region, wherein said second side is an opposite of said first side relative to said lithographic feature region and is parallel with said first side, wherein said lithographic feature region has a first width defined as the vertical distance between said first side and said second side, wherein said first side and said second side have a same length along said lithographic feature region, and said horizontal grating region and said vertical grating region are provided along the full extension of said length, an opaque layer formed on the top surface of the substrate and having a first side and a second side parallel with said first side, wherein said opaque layer has a second width defined as the vertical distance between said first side and said second side of the opaque layer, wherein said horizontal grating region extends vertically from said first side of said opaque layer, and wherein said first width of said lithographic feature region is equal to said second width of said opaque layer.