SEMI PV48 - Specification for Orientation Fiducial Marks for PV Silicon Wafers
Dimensional metrics as described in several SEMI Test Methods do not define wafer physical orientation during measurement.
Measurements of the same wafer differently oriented (rotated or flipped between measurements) result in permuted data sets, within the limits of the measurement equipment precision. This may generate confusion or at least discussions during claim handling or specification verification.
It may also benefit some solar cell process steps to orient a wafer in a specified or preferred orientation.
Therefore orientation fiducial marks are required that allow unique orientation of square or pseudo-square silicon (Si) wafers during measurement or processing.
Many PV Si wafers are currently marked to enable tracing and to tracking. These marks may be used also as orientation fiducial marks.
This Specification defines how current marks may be used as orientation fiducial marks.
It defines also how to apply an orientation fiducial mark on an otherwise unmarked wafer.
This Specification covers square and pseudo-square Si wafers for photovoltaic (PV) applications, with a nominal edge length ≥125 mm and a nominal thickness ≥100 µm.
It may be applied to single crystalline as well as to multicrystalline Si wafers.
It applies to PV Si wafers that are marked with one of the marks as described in SEMI PV29 and SEMI PV32.
It applies also to wafers with only a fiducial mark according to § 7.2.
Referenced SEMI Standards
SEMI PV29 — Specification for Front Surface Marking of PV Silicon Wafers with Two-Dimensional Matrix Symbols
SEMI PV32 — Specification for Marking of PV Silicon Brick Face and PV Wafer Edge