SEMI Standards
What Are SEMI Standards and What Is Their Purpose?
SEMI Standards are global specifications developed by the Semiconductor Equipment and Materials International (SEMI) association to ensure interoperability, consistency, and efficiency across semiconductor and electronics manufacturing.
These standards define how factory host systems and equipment communicate, exchange data, and manage automation workflows, enabling seamless integration and dependable operations. Regularly reviewed and refined by industry experts, SEMI Standards help manufacturers, equipment suppliers, and end-users keep pace with evolving production demands to maintain high reliability and performance as technologies evolve.
SECS/GEM Standards
for 200 mm, Backend Assembly, LED, PV Industries
The SECS/GEM suite, including SEMI E4, E5, E30, and E37, establishes the foundational communication framework between factory hosts and manufacturing equipment.
It defines standard messaging protocols, state models, data collection, and alarm mechanisms, allowing equipment from different manufacturers or vendors to integrate effortlessly into factory automation systems.
Commonly adopted in 200mm fabs, backend assembly, LED, and photovoltaic production, SECS/GEM ensures stable and reliable connections across diverse manufacturing environments.
GEM300 Standards
For Wafer Fabs/ 300 mm Environments
The GEM300 standard family extends SECS/GEM to fully automated 300 mm wafer fabs, introducing carrier handling, substrate tracking, and job management capabilities.
It encompasses key SEMI specifications such as E87 (Carrier Management), E90 (Substrate Tracking), E94 (Control Job Management), and E40 (Process Job Management), alongside E116 (Equipment Performance Tracking) and E39 (Object Services).
These standards together support sophisticated material-transport systems, control jobs, multi-step process jobs and substrate management logic, enabling high throughput, precise real-time traceability, consistent performance and unified automation across complex wafer-fab operations.
SEMI E4
SECS-I (Message Transfer)
SEMI E4 defines the original serial link for SECS/GEM communication between a factory host and equipment. It specifies how messages are framed, acknowledged, retried, and sequenced over RS-232, including timing rules and error recovery.
While modern fabs typically prefer Ethernet (HSMS/E37), E4 remains important for legacy interfaces and embedded controllers that still expose serial ports.
Understanding E4 helps ensure deterministic sessions, predictable timeouts, and clean reconnect behavior—critical when a tool or host must survive cable swaps, power cycles, or intermittent signal quality. In practice, E4 carries SECS-II (E5) messages: once the link is established, all higher-level commands—alarms, remote commands, variable access, recipe flows—ride on E4’s reliable transport.
For brownfield upgrades, E4 knowledge shortens bring-up, clarifies logs, and reduces custom handshakes, allowing factories to standardize behavior across mixed generation equipment.
Products that support SEMI E4
SEMI E5
SECS-II (Message Content)
SEMI E5 defines the structure and semantics of SECS/GEM messages: typed data items, hierarchical lists, and request/response pairs organized into Streams and Functions.
This is the language that gives meaning to automation—reporting collection events, raising and clearing alarms, reading and writing variables, invoking remote commands, and managing process programs.
Because E5 is transport-agnostic, the same messages work over serial SECS-I (E4) or Ethernet HSMS (E37), preserving interoperability as networks evolve. Its compact binary format is efficient on slow links and robust at scale, enabling consistent behavior from single-module tools to complex cluster systems.
Most adjacent SEMI standards select subsets or patterns of E5 transactions to fulfill their domains (material logistics, job control, performance tracking). Mastering E5 enables faster integrations, clearer diagnostics, and easier conformance testing—your host and equipment speak the same precise, typed vocabulary, reducing ambiguity and accelerating time to production.
Products that support SEMI E5
SEMI E30
GEM (Generic Equipment Model)
GEM standardizes how factories monitor and control equipment through a consistent, vendor-neutral interface. It defines core services—state models, alarms, collection events and reports, trace sampling, variables, remote commands, process program (recipe) management, and clock/ID management—implemented using SECS-II (E5) over either SECS-I (E4) or HSMS (E37).
With GEM, a host can bring a tool online, enable data collection, enforce operating states, start/stop processes, and capture contextualized results without bespoke protocols. For equipment makers, GEM provides a clear roadmap to compliance and reduces one-off engineering per customer; for fabs, it means reusable host code, predictable behaviors, and faster qualification.
GEM also underpins many domain standards (for example, E40, E87, E90, E94, E116), so conformant tools slot into broader automation flows. The result is shorter integration cycles, improved diagnosability, and higher uptime across heterogeneous lines, whether deploying new tools or retrofitting legacy assets.
Products that support SEMI E30
SEMI E37
HSMS (High-Speed SECS Message Services)
HSMS moves SECS/GEM to Ethernet/TCP, delivering higher throughput, lower latency, and simpler wiring than serial links. It specifies active/passive roles, session establishment (Select), keep-alive (Linktest), orderly disconnect (Separate), and timeout behavior, ensuring reliable long-lived connections between host and equipment.
HSMS carries SECS-II (E5) payloads unchanged, so existing GEM logic works as-is while benefiting from modern networking. In practice, most deployments use the HSMS-SS (single-session) profile, though multi-session variants can isolate traffic classes.
Deterministic session rules and explicit liveness checks make HSMS resilient under load and during network events, supporting centralized host architectures and large tool fleets. For integrators, HSMS reduces custom cabling, eases diagnostics, and scales easily from lab setups to high-volume fabs—all while preserving the semantics defined in E5 and GEM.
Products that support SEMI E37
SEMI PV2
Photovoltaic GEM Subset
PV2 adapts GEM for photovoltaic lines by defining a focused, interoperable subset of capabilities and precise implementation details. It streamlines bring-up by prescribing formats for common data items, a minimum set of variables and events, and simplified process program management (unformatted recipes).
PV2 tightens behaviors around reporting and timekeeping, enabling hosts to correlate metrics across diverse PV tools without vendor-specific conventions. By omitting less critical SECS-II transactions, PV2 lowers the compliance burden while preserving essential control and visibility. The result is consistent integrations, faster acceptance, and easier support across multiple equipment suppliers.
For factories, PV2 means reliable data for yield and throughput analysis; for tool builders, it provides a clear, bounded target that reduces engineering effort yet meets production automation needs.
Products that support SEMI PV2
SEMI E122
Common Equipment Model
E122 promotes a consistent, machine-readable way to describe a tool’s capabilities—functions, states, data, resources, and constraints—so hosts can discover and interact with equipment predictably.
Acting as an information model that complements SECS-II messaging, it standardizes names, relationships, and semantics, reducing ambiguity and custom mapping. With a shared vocabulary, higher-level applications can reason about different tools using the same concepts, accelerating onboarding and enabling smarter automation strategies.
E122 also harmonizes with adjacent standards (data collection, job control, performance tracking), positioning the model as a single source of truth for what the equipment exposes.
The payoff is faster integrations, clearer diagnostics, and easier evolution as tools add features—hosts can query capabilities rather than reverse-engineering behaviors from manuals.
Products that support SEMI E122
SEMI E39
Object Services
E39 brings object-oriented structure to SECS/GEM by representing equipment resources as discoverable objects with attributes, methods, and events.
Chambers, load ports, and robots can present consistent interfaces while allowing vendor-specific extensions. Hosts browse objects, inspect properties, and invoke standardized operations that map cleanly onto SECS-II messages, improving clarity and reuse.
This abstraction is especially helpful for complex cluster tools, where modular subsystems evolve independently. E39 reduces tight coupling in host logic, streamlines conformance, and improves log readability: interactions become explicit object operations rather than ad-hoc message sequences.
For equipment makers, E39 provides a scalable way to expose capabilities without exploding message permutations; for fabs, it shrinks custom code and shortens time to stable production.
Products that support SEMI E39
SEMI E40
Process Job
E40 standardizes the concept of a process job—the unit of recipe execution within equipment.
A process job encapsulates material, recipe, parameters, and priorities, with defined commands and states for creation, start, hold, resume, and completion. By giving hosts a uniform way to orchestrate run-level work, E40 simplifies coordination across diverse tools and complements logistics (E87) and control authorization (E94).
It enables precise traceability—what ran, on which material, with which settings—and supports parallel processing and recovery flows.
For equipment makers, E40 clarifies the interface surface for execution control; for fabs, it reduces bespoke sequences, accelerates qualification, and improves exception handling through consistent reports and events.
Products that support SEMI E40
SEMI E87
Carrier Management
E87 defines how equipment and host coordinate the identification, verification, and movement of carriers (for example, FOUPs or cassettes).
It covers load port behavior, accept/reject rules, ID verification, mapping checks, docking/undocking, and related events and variables. The goal is to ensure the right carrier is in the right place, with known contents, so that subsequent process or transport steps can proceed safely.
E87 integrates tightly with substrate tracking (E90) and job orchestration (E40/E94), keeping material flow and execution context aligned.
For equipment makers, E87 offers a predictable interface to AMHS and operator handling; for fabs, it reduces mis-loads and improves cycle time with standardized states and diagnostics during carrier exchange.
Products that support SEMI E87
SEMI E90
Substrate Tracking
E90 provides fine-grained tracking of substrates (wafers, cells, panels) as they move through equipment, from load ports into process modules and back out again.
It defines substrate identities, locations, states, and the events that signal arrival, processing, and departure. This enables hosts to maintain accurate work-in-process views, reconcile recipe results to specific material, and quickly detect mix-ups.
E90 aligns with E87 (carrier management) and with E40/E94 (job control) so material flow and execution context remain consistent.
For equipment builders, implementing E90 clarifies the instrumentation required to report movement and processing milestones; for factories, it underpins genealogy and yield analysis by tying data and alarms to individual substrates.
Products that support SEMI E90
SEMI E94
Control Job
E94 defines the control job, a higher-level container that authorizes and governs one or more process jobs on the tool.
A control job specifies allowed material, permitted recipes, sequencing constraints, and preconditions or resources that must be available. Once released, it enforces wafer-start control, lot integrity, and coordinated runs across chambers.
E94 provides uniform commands, states, and reports for creating, starting, holding, and completing control jobs, as well as for handling exceptions. Working in concert with E87 (carriers), E90 (substrates), and E40 (process jobs), it keeps material logistics and recipe execution synchronized.
The result is predictable automation, stronger compliance with fab rules, and clearer traceability from authorization through completion.
Products that support SEMI E94
SEMI E116
Equipment Performance Tracking
E116 standardizes how equipment reports performance metrics so hosts can calculate availability, utilization, and productivity consistently.
It defines a time-based state model, event semantics, and data sets used to derive KPIs such as uptime, downtime categories, mean time to repair, and throughput. By unifying naming and transitions, E116 removes ambiguity in factory dashboards and enables apples-to-apples comparisons across vendors and tools.
Implementations frequently pair E116 with GEM data collection, allowing near-real-time feeds into MES, OEE, or analytics platforms.
For equipment makers, E116 clarifies what to instrument and how to categorize interruptions; for fabs, it accelerates root-cause analysis and continuous improvement by providing reliable, structured signals rather than ad-hoc logs.
Products that support SEMI E116
SEMI E142
Substrate Mapping and Data Exchange
E142 specifies how equipment and hosts represent and exchange substrate “maps” (for wafers, strips, frames, trays, etc.) so every system interprets per-location results consistently.
It defines the structure and required content of map data—such as layout, coordinate addressing, and per-die/unit state (e.g., pass/fail, bin/grade, defect categories)—and the rules for how map information is transferred and updated across the interface.
Standardized mapping underpins inkless manufacturing flows, where downstream tools rely on the electronic map instead of physical marking, and it enables reliable sorting, routing, yield analysis, and end-to-end traceability.
For equipment makers, E142 provides a consistent map model and exchange behavior to integrate cleanly with factory hosts; for fabs, it reduces interpretation ambiguity across toolsets and improves the fidelity of genealogy, disposition, and analytics that depend on accurate per-location outcomes.
Products that support SEMI E142
SEMI E148
Time Synchronization and Clock Management
E148 specifies how equipment maintains and exposes accurate time, including synchronization to external references and consistent timestamp behavior.
It defines requirements for clock accuracy, drift handling, adjustment procedures, and reporting so hosts can trust event and data timestamps.
Accurate time underpins everything from sequence reconstruction and SPC windows to cross-tool correlation in high-volume manufacturing. E148 often complements GEM data collection, ensuring that alarms, traces, and reports are aligned to factory time with predictable skew and adjustment semantics.
For equipment makers, E148 guides robust clock design and diagnostics; for fabs, it reduces confusion during incident analysis and improves the integrity of genealogy and analytics that rely on precise ordering.
Products that support SEMI E148
SEMI E157
Module Process Tracking
E157 introduces module-level process tracking so hosts can follow recipe execution inside complex equipment.
It defines events, data, and state semantics for process modules and sub-steps, enabling granular visibility beyond start/complete at the tool level.
With E157, hosts can correlate parameters and outcomes to specific module phases, improving traceability, tuning, and root-cause analysis. The standard aligns with E40 (process jobs), E94 (control jobs), and E90 (substrate tracking) so that execution context, authorization, and material movement stay synchronized.
For equipment builders, E157 clarifies instrumentation at the module boundary; for fabs, it enhances yield learning by connecting detailed execution segments to measured results and alarms.