After the Taiwan Printed Circuit Board Association (TPCA) chose the Generic Model for Communication and Control of Manufacturing Equipment (GEM) standard for equipment connectivity, they asked Cimetrix to present at a TCPA technical conference explaining some of the most important features and benefits of GEM. After Brian Rubow (Cimetrix Director of Client Training and Support) presented they asked him to write a summarizing article which was published by TPCA during the October 2017 TPCA show. Today, we are re-publishing the article as we launch an extensive features/benefits blog series coming up in 2018.
SECS/GEM refers to a set of SEMI standards that govern the communication between manufacturing equipment and factory host computer systems. The Message layer standard, SEMI E5 SECS-II, defines a generic message structure and a library consisting of many standardized messages. The Protocol layer standard, SEMI E37 High-Speed Message Service (HSMS), defines a binary structure to transfer SECS-II messages using TCP/IP. SEMI E30 GEM, defines a minimum set of requirements, additional (optional) capabilities, use cases and user scenarios for a subset of SECS-II messages.
SECS/GEM is implemented on an equipment, and is used by the factory to implement command and control functions. Since it is an industry standard, any SECS/GEM-compliant host software can communicate with any SECS/GEM-compliant equipment. When fully implemented on the equipment, the standards enable factory software to completely control and monitor the equipment by means of its SECS/GEM interface. These standards provide numerous benefits to both equipment manufacturers and factories. Several of these benefits are highlighted in this article.
SECS/GEM Reduces Equipment Integration Costs
Factories are typically owned and operated by multinational enterprises which purchase equipment from a variety of equipment manufacturers. Even though the control software is different on every equipment, the factory is required to integrate the equipment to operate in harmony. While it is possible to independently integrate each equipment with custom software, this is not cost or time effective.
The situation is similar for equipment manufacturers, who sell their products to diverse factories across the globe. Data collection and application software at every factory are different. The equipment manufacturer is required to help the factory integrate the purchased equipment. While it is possible to develop a custom integration solution for each factory, this is again not cost effective. Every time a factory asks for custom integration features, these costs get passed on to the factory itself.
Custom software, whether developed by the equipment manufacturer or the factory, is expensive to create and maintain, and tends to be of lower quality than desired. By contrast, the SECS/GEM standards define how to create a standardized interface on any manufacturing equipment. Equipment manufacturers benefit by developing one interface for all of their customers. Factories benefit by reusing the same integration software for all of their purchased equipment. Reuse of this software and technology both by the factory and equipment manufacturer raises the software quality, reduces costs and allows for more functionality. The equipment manufacturer and factory alike can invest not only in the minimum features required, they can also implement advanced functionality that is otherwise unaffordable. If they only have to support SECS/GEM, then equipment manufacturers can publish more data and support more advanced control. In turn, factories can then use the additional data to improve product quality and productivity.
SECS/GEM Is Applicable to All Manufacturing Equipment
Because SECS/GEM is divided into Fundamental Requirements and Additional Capabilities, it can be implemented on any manufacturing equipment, regardless of size and complexity. Additional Capabilities are optional because they are not always needed. For example, some equipment do not have recipes and therefore do not need to implement the Recipe Management Additional Capability.
SECS/GEM also scales well with the magnitude of an equipment’s data. For example, a very simple equipment or device might publish 10 different collection events, whereas a complex equipment might publish 5000 different collection events; yet both can use the same SECS/GEM technology.
Innumerable Applications Can Be Supported Using a SECS/GEM Interface
Everything that happens on an equipment can be tracked. Any remote control features and system configuration can be supported. The more data that is published by an equipment, the more software applications a factory can implement. A SECS/GEM interface makes it possible to implement applications for statistical process control, troubleshooting, predictive maintenance, feedforward/feedback process control, equipment utilization, material tracking, recipe validation and many more. Such applications often reduce the need for an operator interface on the equipment, thereby reducing the number of operators in the factory. Recipe management allows factories to minimize scrap. For example, use the SECS/GEM interface to store golden recipes in a central location and also to ensure that the correct recipe is used on the material.
SECS/GEM Uses Network Bandwidth Very Efficiently
There are several features that make SECS/GEM naturally efficient. First of all, every SECS/GEM interface acts as a message broker. Because the broker runs on the equipment, unsubscribed data is not published on the network. For host software to receive alarm, collection event, or trace data messages, it must first subscribe. Since subscriptions for each alarm, collection event, and trace data are managed separately, the equipment can implement a single SECS/GEM interface that publishes all alarms, collection events and trace data requested by all factory applications without wasting network bandwidth with unnecessary data. Moreover, when the host subscribes for trace data, it specifies the data collection rate, making SECS/GEM much more efficient and useful than protocols that publish data at a hard-coded rate.
Additionally, all SECS/GEM messages are always transmitted in an efficient binary format. This uses much less bandwidth than protocols that transmit in ASCII format. Despite using a binary format, SECS/GEM messages are also easily converted to and from a standardized XML notation.
SECS/GEM Enjoys Enormous Industry Support
SECS/GEM has been the backbone of factory/equipment communication and control systems for years in the semiconductor industry. This means that all semiconductor manufacturing today completely relies on SECS/GEM communication. 300mm semiconductor factories have been running with full automation based on SECS/GEM communication since the late 90s—large companies like TSMC, Samsung, Micron, Intel, Toshiba and many others utilize SECS/GEM 24/7 in every factory. Other industries like Flat Panel Display, High-Brightness LED and Photovoltaic have also officially adopted SECS/GEM because they recognized how SECS/GEM features can be applied to any manufacturing equipment to support mission-critical applications.
SECS/GEM Is Self-Describing
Although the standard requires GEM documentation to be provided with the equipment, SECS/GEM supports multiple approaches for host software to automatically adapt to an equipment’s SECS/GEM interface. There are messages for the host software to ask for the list of available alarms, status variables, equipment constants, and, for newer implementations, a list of available collection events and data variables. These messages make SECS/GEM plug-and-play. Additionally, the equipment manufacturer can provide a standardized XML file that provides a full description of the SECS/GEM interface and its features.
Summary
These are just some of the many benefits of using SECS/GEM technology, both for factories and equipment manufacturers. SECS/GEM is proven technology that is available today.
