SEMI E10 - Specification for Definition and Measurement of Equipment Reliability, Availability, and Maintainability (RAM) and Utilization

Volume(s): Equipment Automation Hardware
Language: English
Type: Single Standards Download (.pdf)

This Document establishes a common basis for communication between users and suppliers of semiconductor manufacturing equipment by providing a standardized methodology for measuring reliability, availability, and maintainability (RAM) and utilization performance of equipment in a manufacturing environment.


The Document defines six mutually exclusive basic states into which all conditions and periods of time for an equipment system must fall. One state called the unscheduled downtime state (UDT) defines a ‘failed’ state for an equipment system. The measurement of equipment system reliability in this Document concentrates on the relationship between equipment system failures and equipment system usage.


All metrics defined herein are applicable to equipment systems that include noncluster tools, single-path cluster tools (SPCTs), equipment modules within a multi-path cluster tool (MPCT), intended process sets (IPSs) of equipment modules, and MPCTs. This Document defines a treatment of RAM and utilization measurement for MPCTs by first defining performance of IPSs as a function of equipment module-level performance, then defining MPCT performance as a function of IPS performance. For each metric presented, any special handling required for IPSs and MPCTs is defined.


This Document defines basic metrics for:

• Reliability — Including mean time between failures and mean cycles between failures.

• Availability — Including total uptime, operational uptime, equipment-dependent uptime, and supplier-dependent uptime.

• Maintainability — Including mean time to repair, mean time to (perform) preventive maintenance, mean time offline, total failure rate, and impairment rate.

• Utilization — Including total utilization and operational utilization.


Supporting material included in this Document addresses concepts for measurement of mean time between failure (MTBF) uncertainty and reliability growth and degradation.


Referenced SEMI Standards

SEMI E30 — Specification for the Generic Model for Communications and Control of Manufacturing Equipment (GEM)
SEMI E35 — Guide to Calculate Cost of Ownership (COO) Metrics for Semiconductor Manufacturing Equipment
SEMI E58 — Automated Reliability, Availability, and Maintainability Standard (ARAMS): Concepts, Behavior, and Services
SEMI E79 — Specification for Definition and Measurement of Equipment Productivity
SEMI E116 — Specification for Equipment Performance Tracking

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