- SEMI MF657 - Test Method for Measuring Warp and Total Thickness Variation on Silicon Wafers by Noncontact Scanning
This standard was technically approved by the global Silicon Wafer Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on April 25, 2007. It was available at www.semi.org in June 2007. Originally published by ASTM International as ASTM F 657-80; previously published July 2005.
Warp and thickness variation of silicon wafers can significantly affect the yield of semiconductor device processing. Knowledge of these characteristics can help the supplier and customer determine if the dimensional characteristics of a particular wafer satisfy given geometrical requirements. Changes in wafer warp during processing can adversely affect subsequent handling and processing steps This test method is suitable for measuring the warp and TTV of silicon wafers used in semiconductor device processing in the as-sliced, lapped, or polished condition and for monitoring thermal and mechanical effects on the warp of silicon wafers during device processing. This test method covers a noncontacting, nondestructive procedure to determine the warp and total thickness variation (TTV) of clean, dry silicon wafers in a free (unclamped) condition. The procedure uses a three-point back surface reference plane for determining warp. The test method is applicable to circular silicon wafers from 50 mm (or 2.0 in.) to 200 mm in diameter, and 100 m (or 0.004 in. approximately) and larger in thickness, independent of thickness variation and surface finish.
Referenced SEMI Standards
SEMI M1 — Specifications for Polished Monocrystalline Silicon Wafers
SEMI M59 — Terminology for Silicon Technology