System and method for facilitating wafer alignment by mitigating effects of reticle rotation on overlay

A method for facilitating wafer alignment, comprising the steps of:

• using a reticle, including:
• a design area;
• a first set of scribe marks;
• and
• a second set of scribe marks symmetric to the first set of scribe marks relative to the design area;
• printing the first and second sets of scribe marks on a surface layer of the wafer associated with a first field location;
• and
• printing the first and second sets of scribe marks on the surface layer of the wafer associated with a second field location adjacent to the first field location such that the first set of printed scribe marks of the first field location and the second set of printed scribe marks of the second field location form a composite set of printed scribe marks which substantially negates rotational error associated with the reticle employed in a lithographic printing process.

A reticle for use in a lithographic process, comprising:

• a design area;
• a first set of scribe marks located along a first side of the design area;
• and
• a second set of scribe marks located along a second side of the design area opposite the first side, the first and second sets of scribe marks having an associated symmetry relative to the design area such that, upon being printed onto adjacent fields of a wafer, the first set of printed scribe marks of one of the adjacent fields and the second set of printed scribe marks of another of the adjacent fields reticulate to form a composite set of printed scribe marks on the wafer which substantially negates rotational error associated with employing the reticle in a lithographic printing process.

A system for facilitating wafer alignment, comprising:

• a reticle, including:
• a design area;
• a first set of scribe marks located along a first side of the design area;
• and
• a second set of scribe marks located along a second side of the design area symmetric to the first set of scribe marks relative to the design area;
• at least one system for locating a composite set of scribe marks as printed on a surface layer of the wafer, the composite set of scribe marks being formed by aggregating the first set of scribe marks as printed on the surface of the wafer associated with a first field location and the second set of second marks as printed on the surface of the wafer associated with a second field location adjacent to the first field location;
• and
• a processor for controlling general operations of the at least one system, the processor determining a geometric characteristic of the composite set of printed scribe marks, the processor employing the geometric characteristic to facilitate relative alignment of the wafer and reticle.

A system for aligning a wafer, comprising:

• means for locating a composite set of scribe marks on a surface layer of the wafer, the composite set of scribe marks being formed from a first and second set of scribe marks printed on the surface layer of the wafer respectively associated with first and second adjacent fields, the first and second sets of printed scribe marks having an associated symmetry such that the composite set of scribe marks substantially negates reticle rotation error;
• means for determining the a geometric reference characteristic of the composite set of scribe marks, the geometric reference characteristic being a virtual alignment mark;
• and
• means for aligning the wafer using the virtual alignment mark as a reference.