SECS (SEMI Equipment Communications Standard)/GEM (Generic Equipment Model) is the communication interface protocols for communication between semiconductor equipment and a fab host. Fab host is a software application that controls and monitors equipment processing using SECS/GEM protocol. SECS/GEM compliant equipment communicates with the fab host using either RS232 (using SEMI standard E4 – SECS-I) or TCP/IP (using SEMI standards E37 and E37.1 – HSMS) or. The SECS/GEM standard interface helps to start and stop equipment processing, collect measurement data, select recipes for products and change variables. With SECS/GEM, all processes is carried out in a standard way. SECS/GEM protocol is standardized by the non-profit association SEMI (Semiconductor Equipment and Materials International).
Let us understand 3 basic SEMI standards in brief: •
SEMI E30 GEM Standard – SEMI E30 is the core standard that describes the nature of the equipment, state machine and few rules like which SECS-II messages should be used, in which situations, and also what the output should be. It defines the functionalities like Status Data Collections, Trace Data Collection, Alarms Management, Spooling, Remote Command, etc.
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SEMI E5 SECS-II – SEMI E5 describes the interpretation of (APIs) messages exchanged between the equipment and a host. It also outlines message inputs/outputs data structure, data item format, acknowledgment codes. SEMI E37 HSMS – SEMI 37 is 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 uses serial communication. This is the layer where the SECS-II messages are encoded into HSMS message format.
GEM standard is called as SEMI standard E30 but is also referred to as the GEM or SECS/GEM standard. GEM standard can be used by both device manufacturers and equipment suppliers as it lists downs common set of equipment behavior and communication capabilities to provide functionality as well as the flexibility to support manufacturing. As the GEM standard has few semiconductor-specific features, it has been adopted by other manufacturing industries as well, such as PV. Benefits of SECS/GEM standard: Benefits to Fab Host: • Start and Stop processing • Select, download and upload recipes from/to the equipment • Query the equipment for values of various process parameters and equipment configuration • Set equipment configuration parameter values • Define reports of various variables and associate them with events such as lot start or wafer complete Benefits to Equipment: • Send alarms to the fab host • Send various events and associated reports to the fab host SECS/GEM is a communication protocol, which is a platform, technology, and programming language independent. The host side of a connection is executing on a computer system provided by the factory, and the equipment side of a connection is running on a controller computer provided by the equipment manufacturer. This gives the fab as well as the equipment manufacturer flexibility, interoperability, and platform independence. Both, the fab and the OEM can develop their software application without having to worry about communication compatibility, as long as both of them are adhering to SECS/GEM standards.