Standard · Standards & Organisations
SEMI E30 (Generic Model for Communications and Control of Manufacturing Equipment)
The SEMI standard, known as GEM, that defines the behaviour and message set a fab tool must support so host software can collect data, set recipes and control processing.
It sits on top of the SECS-II message protocol.
- Also known as
- GEM, SECS/GEM
- Type
- Standard
- Domain
- Standards & Organisations, Fab, packaging & assembly
Notes
SECS/GEM compliance is a standard purchase requirement for fab equipment because it is what makes automated factory integration possible.
Overview
SEMI E30 is the SEMI specification for the Generic Model for Communications and Control of Manufacturing Equipment, known as GEM, which defines how a fab tool should behave and which messages it should use when a factory host computer talks to it. It lets host software collect data, manage recipes and start or stop processing in the same way on equipment from different suppliers. GEM sits on top of the SECS-II message format and leaves the physical transport to other standards.
How it works
SECS-II (SEMI E5) supplies the vocabulary. Messages are grouped into streams, which are categories of activity, and functions, which are individual messages within a stream; stream 1, for example, covers equipment status and stream 7 covers process programs. SECS-II leaves many choices open, so GEM picks one consistent way of doing each job and adds the behaviour the host can see through the link.
That behaviour is described with state models, such as a control state that is offline, online under local control or online under remote control, and a processing state that shows whether the tool is idle or running. On top sit capabilities: collection events linked to reports of chosen variables, alarms reported when set or cleared, remote commands such as start, stop and abort, recipe upload and download, and trace data sampling. The standard separates fundamental requirements from additional capabilities, and compliance is declared by the supplier rather than certified.
Transport is a separate layer. Most current tools use HSMS (SEMI E37) over TCP/IP, with the host usually acting as client, while older tools use the serial SECS-I link (SEMI E4). Further SEMI standards build on GEM for 300 mm automation of process jobs, carriers and substrate tracking.
Examples
- A host system sending a remote command to start processing on an etch tool after checking which recipe the tool reports as selected.
- A deposition tool sending a collection event at the end of each wafer, with chamber variables attached, for statistical process control.
- Back-end tester and handler equipment models (SEMI E122 and E123) that extend GEM for assembly and test.
- Solar cell production lines, which adopted SECS/GEM in 2008 through a SEMI guide combining HSMS, SECS-II and subsets of GEM.
Why it matters
Every automated fab depends on its tools reporting events, alarms and measurements to the host and accepting recipes and commands from it, and GEM is the common language for that exchange. Fab automation and MES engineers build host connections to it, equipment software engineers at tool suppliers implement it, and the data it carries feeds process control and yield analysis.
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