Thursday, 17 January 2019

Introduction to SECS/GEM - Beginner's Guide

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Introduction to SECS/GEM - Beginner's Guide
SEMI E30 GEM standard
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This guide is intended to give an overview and basic introduction of SECS/GEM and its usage in the semiconductor industry to the beginner. And It is NOT INTENDED to substitute or serve as complete reference of the standards. For a complete reference of the standards, please refer to SEMI.

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Introduction to SECS/GEM Standard

SECS (SEMI Equipment Communication Standards) and GEM (Generic Model For Communications and Control Of Manufacturing Equipment) standard is published and maintained by, an international organization of semiconductor manufacturers, is an organization body that governs the standard for semiconductor manufacturing. To understand the SECS/GEM standards you will need to purchase the following 3 basic standards from SEMI:

  • SEMI E30 GEM Standard - Defines the behaviors of equipment (Business Rules), state machine and some rules like which SECS-II messages should be used, in what situations, and what the resulting activity should be.
  • SEMI E5 SECS-II - Defines the details of the interpretation of messages (APIs) exchanged between equipment a host.
  • SEMI E37 HSMS - High Speed SECS Message Services. This is a transport layer based on TCP/IP protocol and a successor of the previous SEMI E4 SECS-I standard that is based on serial communication.

SECS/GEM interface is developed in the 80s but the concept to the modern technology is very similar. As an illustration, let's consider Web Service technology. An enterprise application server uses Web Service to interface with other services or hosts via HTTP or TCP/IP. And let's compare each layer to the SECS/GEM:

Comparison Web Service vs SECS/GEM
Comparison Modern Technology - Web service SEMI - SECS/GEM
Behaviors, Business Rules "Enterprise Application Server" defines all the business rules and behaviors of the application. In SECS/GEM, SEMI E30 GEM standard defines the generic equipment behaviors, state machines, rules that govern what the Host can or can't do.
Message Protocol Web services uses SOAP message which details the messages structure exchanged between Client/Server. In SECS/GEM, SEMI E5 SECS-II uses SML (SEMI Markup Language) to define the message details and structure to be exchanged between Equipment/Host.
Transport Protocol Web services SOAP messages can be transported via HTTP or TCP/IP protocol. In SECS/GEM, SECS-II messages can be transported with SEMI E37 HSMS over TCP/IP protocol.