SEMI E4 – SECS-I Specification for Equipment Automation Software
- SECS-I
- SEMI E30
- SEMI E5
- SEMI E37
- SEMI E95
In the semiconductor manufacturing ecosystem, reliable communication between factory equipment and host systems is critical for productivity, yield, and automation. SEMI E4, also known as SECS-I (SEMI Equipment Communications Standard I), is one of the foundational standards that enables this communication.
At Einnosys, we specialize in building robust equipment automation software and SECS-I communication solutions that help semiconductor fabs connect legacy and modern equipment seamlessly to factory host systems.
What Is SEMI E4 (SECS-I)
SEMI E4 defines the SECS-I protocol, a serial, point-to-point communication standard used for message transfer between semiconductor equipment and a host computer.
SECS-I was created to allow independent equipment manufacturers and software vendors to develop systems that can communicate without needing proprietary or vendor-specific knowledge of each other’s internal design.
In simple terms, SECS-I answers the question:
How should messages be physically and logically exchanged between equipment and a host?
Why SEMI E4 Matters in Semiconductor Manufacturing
Semiconductor manufacturing involves complex processes such as wafer fabrication, inspection, testing, assembly, and packaging. All these processes rely on precise data exchange.
SEMI E4 enables:
- Equipment status reporting
- Process data transfer
- Alarm reporting
- Command and control from host systems
Without a standardized communication method like SECS-I, integrating different tools into a factory automation system would be costly, slow, and error-prone.
SECS-I vs Message Content Standards (SEMI E5)
It is important to understand what SEMI E4 does and does not define.
For message structure and meaning, SECS-I (SEMI E4) works together with:
Understanding SEMI E4 (SECS-I)
What SEMI E4 Defines
What SEMI E4 Does NOT Define
How SECS-I Communication Works
SECS-I uses a serial, point-to-point data path, typically implemented over:
Only one host and one equipment can communicate on a single SECS-I link.
Basic Communication Model
Message Exchange Flow
SEMI Standards Compliance
All our integration services follow SEMI E5 (SECS-II), SEMI E30 (GEM), and SEMI E37 (HSMS) standards, ensuring your tools meet the strict requirements of Malaysia's advanced fabs.
Einnosys SEMI Standards Support Products
Fabs & Assembly/Test/Packaging Products
- SECS/GEM addition & enhancement on legacy equipment – EIGEMBox & EIGEM-HMI
- E84 & E87 addition on legacy equipment – EIGEMBox
- AI/ML-based health monitoring & predictive maintenance – XPump
- Factory host – EIStationController
- Recipe Management System – EIRMS
- AI/ML based Smart FDC with Predictive Analytics – SeerSight
- Analog Gauge Monitoring – EIGaugeMonitor
- Equipment Simulator – EIGEMSim
- Factory host SDK – EIGEMHost & EIGEM300Host
- Chemical Management – EIBarcodeGuardian
- Spare Parts & Vendor Management – EICMMS
OEMs (Original Equipment Manufacturer) Products
Key Technical Features of SEMI E4 (SECS-I)
Physical Layer Definition
SEMI E4 clearly defines:
This ensures hardware compatibility across vendors.
Logical Protocol Layer
Deterministic Communication
Unlike Ethernet-based protocols, SECS-I provides predictable timing, which is useful for certain legacy tools and older fab environments.
Typical Use Cases for SECS-I
SECS-I is still widely used in:
Many semiconductor factories still operate equipment that is decades old but mission-critical.
SEMI E4 allows these tools to remain productive within modern automation architectures.
Equipment Automation Software Using SEMI E4
At the software level, equipment automation software implements SEMI E4 to enable communication between factory tools and host systems.
Core Functions Include:
- SECS-I protocol stack implementation
- Message parsing and validation
- Error handling and retries
- Interface with higher-level standards like GEM (SEMI E30)
At Einnosys, we design and deploy automation software that supports
SECS-I, HSMS, and full GEM compliance, ensuring long-term scalability.
Typical Use Cases for SECS-I
Scenario
A semiconductor fab uses an older wafer inspection tool that supports only SECS-I communication.
Technical Example: SECS-I Communication in Action
Communication Flow
Host sends a command
- Request lot status from the equipment
SECS-I message transmission
- Message is broken into blocks
- Each block includes checksum and sequence information
Equipment responds
- Sends inspection results and status data
Data processing
- Einnosys software converts SECS data into MES-friendly format
Architecture
- Inspection tool → SECS-I (RS-232)
- Host system → Manufacturing Execution System (MES)
- Einnosys SECS-I equipment controller acts as the middleware
Result
- Real-time visibility of inspection data
- No hardware replacement required
- Legacy tool integrated into modern factory automation
Typical Use Cases for SECS-I
While SECS-I is reliable, it has limitations:
Modern fabs often prefer HSMS (SEMI E37), which runs over TCP/IP.
However, SEMI E4 remains essential where equipment upgrades are not feasible.
SECS-I vs Modern Protocols
Benefits of Choosing Einnosys for SECS-I Solutions
- Deep semiconductor domain expertise
- Standards-compliant SECS-I implementations
- Proven experience with legacy and modern tools
- Scalable architecture for future upgrades
Our goal is not just connectivity, but long-term automation reliability.
Role of Einnosys in SEMI E4 Implementations
At Einnosys, we help semiconductor manufacturers and OEMs by providing:
✅ Custom SECS-I Software Development
- Protocol stack design
- Equipment controller software
- Host interface applications
✅ Legacy Equipment Modernization
- SECS-I to HSMS bridging
- Integration with MES and analytics platforms
✅ Factory Automation & Predictive Maintenance
- Data extraction from SECS-I equipment
- Analytics-ready data pipelines
SEMI E4 (SECS-I) is a cornerstone standard in semiconductor equipment communication. It enables reliable, vendor-neutral message transfer and continues to play a vital role in equipment automation.
By combining SECS-I expertise with modern software engineering, Einnosys helps manufacturers bridge the gap between legacy equipment and smart factory automation—without unnecessary cost or risk.
If you are looking to integrate, modernize, or extend your SECS-I based equipment, Einnosys is ready to support your automation journey.
Frequently Asked Questions (FAQ) – SEMI E4 (SECS-I)
What is SEMI E4 (SECS-I)?
SEMI E4 defines the SECS-I communication protocol, which is a serial, point-to-point standard used to exchange messages between semiconductor processing equipment and a host system. It specifies how messages are transferred, but not their content.
What is the difference between SECS-I (SEMI E4) and SEMI E5?
SEMI E4 (SECS-I) defines the message transport mechanism, including physical and logical communication rules.
SEMI E5 defines the message content and structure. Both standards work together to enable full equipment communication.
What types of equipment use SECS-I?
SECS-I is commonly used in:
- Wafer fabrication equipment
- Metrology and inspection tools
- Assembly and packaging machines
- Legacy semiconductor tools without Ethernet support
Is SECS-I still used in modern semiconductor fabs?
Yes. Although newer tools use Ethernet-based HSMS, SECS-I remains widely used in legacy and hybrid fabs due to long equipment lifecycles and proven reliability.
What communication interfaces does SECS-I support?
SECS-I typically operates over:
- RS-232
- RS-422
- RS-485
It uses a serial, point-to-point communication model between one host and one equipment.
Does SEMI E4 define the meaning of messages?
No. SEMI E4 does not define message meaning or equipment behavior. Message interpretation is defined by standards like SEMI E5 and SEMI E30 (GEM).
How is SECS-I different from HSMS?
SECS-I uses serial communication and is point-to-point, while HSMS (SEMI E37) runs over TCP/IP and supports higher speeds and better scalability. However, SECS-I is still essential for older equipment.
Contact US
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5899 Remer Terrace, Fremont,
CA 94555, USA
Tel: +1.805.334.0710
Email: sales@einnosys.com
