Introduction to SECS/GEM

Hello there, I’m Iwin Lee and I’m a software engineer currently working at NexGen Wafer Systems as a Software Lead. I’m passionate about software development and in providing efficient software solutions and designs in the semiconductor industry. My interest in programming started back in 1997 when I was interested in creating websites from scratch for myself and friends as a hobby.

This interest along with my aptitude for math and science subjects led me to my studies in computer engineering. After completing my studies and embarking on my professional career as a software engineer, I gradually discover my strength and passion in programming and software development which led me to choose the technical domain as my career path focus. Being part of NexGen Wafer Systems has given me many opportunities to collaborate and learn from many talented co-workers in the organization and to further expand my expertise in software architecture design and industrial automation.

During my 15+ years working experience in the semiconductor industry with NexGen Wafer Systems and previous organizations, I have had many opportunities to work with SECS/GEM and to lead development projects and efforts for software compliance with the standards. SECS/GEM is the most widely used standards in the semiconductor industry as it has been adopted by semiconductor fabs and chip manufacturers all over the world to achieve automation. For that I would like to provide a simple introduction to SECS/GEM and to GEM300 which is the latest extension of SECS/GEM, followed by a brief overview of the standards without going into too much technical details for the uninitiated.

What is SECS/GEM?

In a nutshell, SECS/GEM is a set of communication interface protocol standards for communication between a semiconductor fab host and semiconductor equipment for monitoring and controlling purposes, allowing a semiconductor fab to automate equipment operations for manufacturing.

The set of standards have been maintained and published by Semiconductor Equipment and Materials International (SEMI), a non-profit international organization that governs the standards for semiconductor manufacturing. A fab (fabrication plant) host is a software system deployed by a fab to communicate with equipment to control and monitor operations of the equipment. SECS is an acronym for Semiconductor Equipment Communication Standard, while GEM is an acronym for Generic Equipment Model. The standards are well documented elaborately and published by SEMI on their website.


In a semiconductor manufacturing line, many different equipment of different model or manufacturer with various functions are being used for production. Without a communication standard, it will be enormously complex for a fab host system to communicate with different equipment to control and monitor the equipment via different custom communication interfaces that need to be defined and managed separately for every different equipment. As a result, huge amount of time and cost will be incurred when deploying and integrating different equipment in a fab automation ecosystem. This can be avoided when the fab host and all different equipment in a fab adhere to a same standard protocol for communication.

By standardizing or providing a common language that should be shared or applied by all semiconductor equipment, SECS/GEM simplifies the communication requirements between a fab host with various equipment in the fab as well as providing a communication framework for the following crucial capabilities and features:

  • Event Notification (For real-time notification of equipment events/activities and associated reports from equipment)
  • Alarm Notification (For real-time notification of alarms from equipment)
  • Data Variable Collection (For fab host to query or gather real-time data from equipment)
  • Recipe Management (For fab host to select, delete, download, upload recipes to/from equipment)
  • Remote Control (For fab host to start, stop, abort, perform custom command for an equipment operation, load and unload material to/from equipment)
  • Adjust Settings (For fab host to change equipment configuration parameter settings)
  • Operator Interface (For exchange of messages with operators)

As SECS/GEM is a communication protocol, implementation of the standard is independent of platform, technology, and programming language used. This gives IC manufacturers and equipment manufacturers the flexibility and interoperability in adopting the standard in their fab host or equipment software using platforms and technologies of their choice without having to worry about communication incompatibility with the other party.

SECS/GEM is also constantly evolving for the better as there is a growing community with the SEMI organization that is continuously reviewing and enhancing the standards for improvements and new requirements in the semiconductor industry.

Overview of SECS/GEM

SECS/GEM comprises of the following set of standards that were developed and published over time by SEMI to define messages, state machines and scenarios to enable factory software to control and monitor manufacturing equipment:

  • SECS-I (SECS Part 1, also referred to as SEMI E4 standard)
  • HSMS (High-Speed SECS Message Services, also referred to as SEMI E37 standard)
  • SECS-II (SECS Part 2, also referred to as SEMI E5 standard)
  • GEM (Generic Equipment Model, also referred to as SEMI E30 standard)

After the inclusion of the GEM standard, SECS/GEM became the commonly used umbrella term to refer to the set of standards for ease of reference. For compliance with SECS/GEM, a fab host or an equipment should be compliant with all the SECS-I, SECS-II, HSMS and GEM (SEMI E4, E37, E5, E30) standards.

SECS came about first as SEMI first published the SECS-I standard for RS-232 serial port communication in the 1980s. Years later, HSMS standard was developed allowing communication over Ethernet using TCP/IP. With HSMS, SECS-I or serial communication became rarely used anymore as network communication using TCP/IP is faster and much easier to set up. Basically both SECS-I and HSHM standards are protocol layers that just define how messages are delivered over RS-232 or TCP/IP between equipment and fab host. SEMI then published the SECS-II standard providing detailed definitions and formats of the messages to be adopted for communications. With SECS-II as a message layer, GEM was later built on top of the SECS-II by defining a generic communication model for equipment behavior and communication using a subset of the message types defined in the SECS-II message layer standard. The GEM standard then became officially designated as SEMI E30 but it is still widely referred to as GEM and used interchangeably with SECS/GEM to refer to the set of standards.


Prior to the introduction of 300mm wafer, the initial SECS/GEM standards were sufficient for IC manufacturers for their wafer fabs production line requirements. With the development of 300mm wafer, the requirements of IC manufacturers started evolving rapidly requiring additional capabilities with the following being the major ones to fulfil the automation requirements and maximizing production of the larger 300mm wafers:

  • Fab host to handle and validate material delivered to equipment.
  • Fab host to refine process controls of equipment.
  • Fab host to manage process jobs to be executed on equipment.
  • Fab host to track movement and state of all material on equipment.
  • Fab host to track equipment performance.

In order to standardize these capabilities to allow fabs to implement automation in a consistent way, SEMI has further advanced the SECS/GEM standards by developing the GEM300 standards which were built upon the GEM (SEMI E30) standard. GEM300 comprises of the following set of standards:

  • Specification for Object Services: Concepts, Behavior, and Services (also referred to as SEMI E39 standard)
  • Specification for Processing Management (also referred to as SEMI E40 standard)
  • Specification for Carrier Management (CMS, also referred to as SEMI E87 standard)
  • Specification for Substrate Tracking (also referred to as SEMI E90 standard)
  • Specification for Control Job Management (also referred to as SEMI E94 standard)
  • Specification for Equipment Performance Tracking (EPT, also referred to as SEMI E116 standard)
  • Specification for Time Synchronization and Definition of the TS-Clock Object (also referred to as SEMI E148 standard)
  • Specification for Module Process Tracking (MPT, also referred to as SEMI E157 standard)

Today, more and more IC manufacturers have adopted the GEM300 standards and require equipment to fulfil at least the SEMI E39, E40, E87, E90, and E94 standards to integrate with their fab automation ecosystem, including for production of smaller wafer sizes such 150mm or 200mm.

NexGen and SECS/GEM, GEM300 Compliance

At NexGen Wafer Systems, we strongly believe that SECS/GEM and GEM300 are still the gold standards for any smart manufacturing ecosystem. By designing our equipment to be compliant with the standards, our equipment can be deployed and integrated quickly, reliably, economically and at scale.

I’m proud to be part of a team of experts with a huge experience in SECS/GEM and GEM300 driving our equipment compliance with the standards as well as providing expertise to efficiently deploy and integrate our equipment with fabs automation ecosystem for many global IC manufacturers in different countries.

As SECS/GEM and GEM300 are constantly evolving in the semiconductor industry, we continuously strive to ensure our line of semiconductor equipment are compliant with the latest SECS/GEM and GEM300 standards to deliver and enable the best fab automation solution for our customers.

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