Semi E40

SEMI E40 defines Processing Management, the standard state model for the process job itself — the single object that represents "run this recipe on this material" from the moment a host creates it until the equipment reports it finished, and it is one layer below Control-Job Management (SEMI E94), which bundles multiple process jobs together, and one layer above Substrate Tracking (SEMI E90), which reports what's happening to the individual wafers inside that one process job. Before a process job can run, E40 requires it to pass through a defined sequence of states — queued, setting up, waiting for start, processing, and pausing or stopping if something interrupts it — and defines exactly which state transitions are legal, so a host always knows what a process job is allowed to do next and what it cannot do from its current state.

The value of a shared state machine here is the same reason any state machine standard pays off: a host and a piece of equipment from different vendors only stay in agreement about what's happening if both sides refuse to invent their own private states, and E40's defined legal transitions are what prevent an equipment implementation from, for example, jumping straight from Queued to Processing Complete without ever actually processing anything, or reporting a Pause from a state the standard says cannot be paused. This matters most during abnormal conditions — if an operator aborts a job mid-run, E40 defines what state that job lands in and what the host is and isn't allowed to assume about the wafers inside it, which is exactly the kind of edge case that causes real integration bugs when a vendor's equipment software quietly deviates from the standard's transition table.

SEMI E40 is strictly about the process job's own lifecycle state — it does not define what happens to the wafers inside the job (that is SEMI E90's scope) or how multiple process jobs get bundled and sequenced together (that is SEMI E94's scope), which is exactly why integrating a new piece of equipment under GEM means implementing all three standards consistently rather than treating any one of them as sufficient on its own.