Semi E118

SEMI E118 specifies the communication interface between a wafer-ID reader — the hardware that optically or electronically reads a laser-marked or OCR identifier off an individual wafer's edge or backside — and the equipment or host system consuming that read, defining how the reader reports a successful read, a failed read, and the decoded ID string itself. E99 standardizes the mechanical and functional requirements for a carrier-ID reader/writer that identifies the FOUP; E118 is the analogous interface standard one level down, for the reader that identifies the individual wafer sitting inside that carrier, since carrier identity and wafer identity answer different genealogy questions and a fab tracking both needs each reader's output delivered through its own defined interface.

The reason wafer-ID reading needed its own interface standard separate from E99's carrier-ID reader/writer spec is that carrier identity and wafer identity are tracked for different purposes at different points in the process flow — a carrier's ID tells the host which FOUP is where, while a wafer's own ID is what lets genealogy and defect data trace back to one specific wafer even after it's moved between carriers or lots. E118 gives equipment builders a fixed way to wire a wafer-ID reader into the rest of the tool's control system, so a fab mixing reader vendors across different process steps still gets the same read-success/read-failure/decoded-ID reporting behavior at every station, rather than writing a custom integration each time a new reader model is installed.

E118 is what lets wafer-level genealogy and defect tracing function independent of carrier movement — by fixing how a wafer-ID reader reports its read status and decoded string to the rest of the tool, it gives fabs the same mixed-vendor interchangeability at the wafer-identity layer that E99 already provides at the carrier-identity layer.