Patent ID: 6879400

Claim:
A metrology target mask for determining proper lithographic exposure dose and focus in a pattern formed in a layer on a semiconductor substrate by lithographic processing comprising: a mask substrate; a first, dose and focus sensitive mask portion on the mask substrate having a first array of elements comprising a plurality of spaced, substantially parallel elements having essentially the same length and width, ends of the individual elements being aligned to form first and second opposing array edges, the pitch of said first array of elements being selected such that, when lithographically printed in a layer on a semiconductor substrate, first array of elements are resolvable, with the lengths of and spaces between said elements being sensitive to both dose and focus of an energy beam; and a second, dose sensitive mask portion on the mask substrate having a second array of elements comprising a central element having a length and a width, and a plurality of spaced, substantially parallel outer elements, each having a length and a width, the widths of the outer elements being less than the width of the central element, edges of the outer elements on each side of and farthest from the central element forming opposing array edges, the pitch of said outer elements being selected such that, when lithographically printed in a layer on a semiconductor substrate the outer elements are not resolvable and width of the second portion is sensitive to dose but not focus of the energy beam, wherein, after projecting an energy beam through the mask and lithographically printing the mask portions in a layer on a semiconductor substrate and determining the widths of the first and second target portions in the layer by measuring distance between opposing array edges in each of the first and second portions, dose and focus of the energy beam during lithographic processing of said layer can be determined.