SEMI P25 - Specification for Measuring Depth of Focus and Best Focus
This specification was technically approved by the Global Micropatterning Committee and is the direct responsibility of the North American Microlithography Committee. Current edition approved by the North American Regional Standards Committee on August 16, 2004. Initially available at www.semi.org September 2004; to be published November 2004. Originally published in 1994.
NOTICE: This Standard or Safety Guideline has an Inactive Status because the conditions to maintain Current Status have not been met. Inactive Standards or Safety Guidelines are available from SEMI and continue to be valid for use.
This document provides a common descriptive vocabulary and outline of basic technique for use by photolithographers in the IC industry to gauge and report the depth of focus, astigmatism, and field curvature of IC photolithographic instruments (e.g., scanners, steppers). [Hereafter referred to as "instrument" or "instruments."]
This specification is limited to the measurement of focus and depth of focus for photolithography as used in the manufacture of integrated circuits and closely allied technologies. Because of the wide variation in equipment techniques, it is not possible to provide a definitive measurement procedure for these parameters. Rather, in this document, a basic guideline is offered.
Referenced SEMI Standards
SEMI P19 — Metrology Pattern Cells for Integrated Circuit Manufacture