Control and Automation Software

SECS / GEM- Data Collection and Communications

With the growing need for semiconductor manufacturing systems to receive information from, and to communicate with, the processing and metrology tools in the fabrication process, it has become essential to have comprehensive data acquisition and communications capabilities in place that facilitate real-time automated information exchange. The value of the manufactured products and the costs of producing and operating a semiconductor manufacturing facility have risen tremendously. Losses due to tool unavailability and down time are significant. Progress has been made to maximize capital utilization by improving overall equipment efficiency. To collect equipment status, availability, and performance data automatically, the equipment must be capable of reporting changes in state, using event messages and equipment variables.
The automation of this information exchange offers significant support to:
  • Achievement of reliability goals
  • Improved process performance (reduce excursions)
  • Accelerated tool qualifications
  • Maximized productivity

Facilitated by Semiconductor Industry Communications Standards

SEMI, (Semiconductor Equipment and Materials Industry), a semiconductor industry organization, has developed communications standards that facilitate the needed communications between the fab host computer and the equipment that serves the manufacturing and development environments.

The SEMI Standards Program covers most aspects of semiconductor process equipment and materials. Compliance to the specific SEMI Equipment Communications Standards and Generic Equipment Model protocols (SECS and GEM), enables standardized communications between fab host computers and semiconductor manufacturing equipment. SECS and GEM are standardized SEMI specified communications protocols.

Put very simply:

  • "SECS" is a protocol to transmit data and control messages in a platform-independent manner.
  • "GEM" is a protocol framework that specifies a common set of required SECS message and data structures that are used on all equipment (tools) to perform the same FAB-specific functions.

The fundamental SEMI specified SECS and GEM standards are listed below:
(The SEMI Standards specifications can be found at

  • SEMI E4 Protocol - a point-to-point communications protocol designed for factory automation messaging that uses low-speed RS-232 links. SECS-II messages sent using E4 are segmented into a sequence of 254 byte packets, each starting with a 10 byte header. The E4 protocol provides automatic error checking and retry capability. E4 messaging is used to transmit and reliably deliver E5 compliant data messages.

  • SEMI E37 Protocol - a SEMI specified communications protocol designed for factory automation messaging that uses high-speed, Ethernet-based TCP/IP communications. The E37 protocol is also referred to as HSMS (High Speed Message Service) and was developed as a higher bandwidth replacement for E4. It also is primarily used to reliably deliver E5 compliant data messages. An E37 link is a higher performance alternative used in place of E4.

  • SEMI E5 Message Data Protocol - a SEMI specified data messaging protocol designed for factory automation that typically uses either E4 or E37 as a link layer protocol. E5 defines platform-independent numeric, Boolean, and printable character data types, along with a standard format for representing these in its message layout. Data items can be scalars, vectors, or sequences (list) of any basic type. There are many predefined messages and application-specific data-types provided in the E5 standard.

  • SEMI E30 Generic Equipment Model - A SECS-based framework that defines the standard semiconductor fabrication messaging interface that is provided across all automated material processing, handling, and testing equipment involved in fabrication or research facility.

SEMI Communications Standards facilitate communications between fab host computers and/or semiconductor manufacturing equipment, enabling:

  • Communications
  • Product tracking
  • Remote e-diagnostics
  • Automated equipment and process control
  • Failure detection
  • Equipment performance tracking
  • Logistics management

Next generation communications standards (i.e. "Interface A"), are currently being defined and refined in hopes of providing more volume and complexity in data acquisition and communications capabilities. The added standards should provide a map for achieving a convenient interface for Equipment Data Acquisition (EDA) using SOAP/XML messages over an HTTP or HTTPS connection.