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SEMI E116-0705 © SEMI 2002, 2005 4  Equipment Constants  Alarm Ma nagement 6.2 An EPT c ompliant implementat ion requires a documented li st of all EPT m odules contained within the equipment . 6.3 An EPT compliant imp…

SEMI E116-0705 © SEMI 2002, 2005 3

5 Terminology

5.1 Abbreviations and Acronyms

5.1.1 EFEM — Equipment Front End Module

5.1.2 EPT — Equipment Performance Tracking

5.1.3 GEM — Generic Equipment Model [SEMI E30]

5.2 Definitions

5.2.1 EPT module — a major component of the equipment that affects processing or throughput.

5.2.1.1 For purposes of simplification, an EPT module executes one and only one task at a time. Each EPT Module

has an EPT state model that is maintained by the equipment.

5.2.2 EPT state — the state of IDLE, BUSY, or BLOCKED within EPT state model.

5.2.3 event report — a message the equipment sends to the host on the occurrence of a collection event.

5.2.4 fault — an exception.

5.2.5 host — the factory computer system or an intermediate system that represents the factory and the operator to

the equipment.

5.2.6 intended function — a manufacturing function that the equipment was built to perform. This includes

transport functions for transport equipment, measurement functions for metrology equipment, as well as process

functions such as physical vapor deposition and wire bonding. Complete equipment may have more than one

intended function. [SEMI E58]

5.2.7 material — the basic unit of process. For the purposes of this standard, material is a set of one or more

substrates.

5.2.8 module — a major component of equipment that contains at least one material location and performs some

task on material. Equipment modules may be aggregates of equipment subsystems, I/O devices, and other modules.

[SEMI E98]

5.2.9 substrate — the basic unit of material on which work is performed to create a product. Examples include

wafers, die, plates used for masks, flat panels, circuit boards, and leadframes. [SEMI E90]

5.2.10 task — a planned and repeatable activity with an expected duration and a definite beginning and end (e.g.,

Move wafer from cassette to stage, Pre-align wafer, Align reticle, Preheat chamber, Increase vacuum). NOTE:

Actual durations may vary.

5.2.11 trigger — an event that causes a change in the state of the equipment. Examples are changes in sensor

readings, alarms, and messages received from the host, and operator commands.

5.2.12 unit 

any wafer, die, packaged device, or piece thereof (included product and non-product units). [SEMI

E10]

5.2.13 user — any entity interacting with the equipment, either locally as an operator or remotely via the host.

From the equipment’s viewpoint, both the operator and the host represent the user. [SEMI E58]

6 Requirements

6.1 An EPT compliant implementation requires provision of certain capabilities defined by other standards:

accessibility to status information, event reporting, alarm management, and provision of an internal time-and-date

clock. These requirements may be satisfied through compliance to SEMI E30 for the following sets of

requirements:

 Clock Services

 Event Notification

 Status Data Collection

SEMI E116-0705 © SEMI 2002, 2005 4

 Equipment Constants

 Alarm Management

6.2 An EPT compliant implementation requires a documented list of all EPT modules contained within the

equipment.

6.3 An EPT compliant implementation requires an EPT state model for the equipment and for each EPT module.

6.4 Each EPT module shall have a documented list of tasks that the module may perform.

7 Conventions

7.1 This document follows the conventions for state model methodology and service definitions used by the SEMI

standards referenced in §4.

7.2 State Model Methodology

7.2.1 A state model has three elements: definitions of each state and sub-state, a diagram of the states showing the

valid transitions between states, and a corresponding state transition table that defines the triggers for each

transition. The diagram of the state model uses the Harel State Chart notation. An overview of this notation is

presented in an Appendix of SEMI E30. The definition of this notation is presented in Science of Computer

Programming 8, “Statecharts: A Visual Formalism for Complex Systems”, by D. Harel, 1987.

7.2.2 Transition tables are provided in conjunction with the state diagrams to explicitly describe the nature of each

state transition. A transition table contains columns for Transition number, Previous State, Trigger, New State,

Actions, and Comments. The “trigger” (column 3) for the transition occurs while in the “previous” state. The

“actions” (column 5) includes a combination of:

1) Actions taken upon exit of the previous state.

2) Actions taken upon entry of the new state.

3) Actions taken that are most closely associated with the transition.

7.2.3 No differentiation is made between these cases.

# PREVIOUS

STATE

TRIGGER NEW STATE ACTIONS COMMENTS

Transition #

7.3 Variable Data Item Definition

7.3.1 The variable item dictionary contained in this document defines the variable name, description, type (format),

access (read/write or read only), and comments about the variable. This is depicted in the format of the following

table:

VARIABLE NAME DESCRIPTION TYPE ACCESS COMMENT

7.4 Event Description

7.4.1 The collection event description table contained in this document includes the event name, the state model

transition, the description, and the data required for the event. This is depicted in the format of the following table:

EVENT NAME STATE MODEL

TRANSITION

NUMBER

DESCRIPTION REQUIRED DATA

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8 Overview

8.1 This section defines the concepts that enable EPT to provide information required for determining equipment

performance.

8.2 Equipment processing times, including throughput and cycle times, are determined by two factors: (1) the

sequence of tasks performed by the equipment’s EPT modules, including the number of each task performed, as well

as the series and parallel relationships between tasks, and (2) the execution time of each individual task. By tracking

equipment systems in terms of modules that perform tasks, it will be possible to precisely identify the affect of both

factors toward overall system performance.

8.3 EPT enables tracking to this level of detail by introducing the concept of an EPT module and the concept of a

task. EPT-compliant equipment are required to report events according to a breakdown of equipment operations

into tasks and EPT modules. An EPT module is an equipment component that affects processing or throughput, and

is capable of executing only one task at a time. Examples of EPT modules include process stations, process

chambers, wafer handling systems, etc. A task is a planned and repeatable activity with an expected duration and a

definite beginning and end. Examples of tasks include the following:

 Move wafer from cassette to stage

 Pre-align wafer

 Align reticle

 Preheat chamber

 Increase vacuum etc.

8.4 EPT-compliant equipment consist of EPT modules that perform tasks. Thus, the state of the equipment can be

effectively modeled as a composition of the states of the EPT modules. In addition, EPT provides detailed

information required for performance tracking by providing the task-level details for each EPT module.

8.5 EPT modules and tasks are to be defined such that each EPT module executes only one task at a time. An

example is given in Related Information §R1-7. Each equipment system must have defined at least as many EPT

modules as tasks that may be performed simultaneously by that system.

8.6 Each task should be defined such that the units involved (e.g., wafers, substrates, reticles), the EPT modules

involved (e.g., process station, robot, etc.), and the task type (e.g., “process”, “support”, etc.) are constant throughout

the duration of the task. A change in any of the following items should result in the start of a new task or completion

of current task:

 Change in material involved (e.g., arrival of wafer, removal of wafer)

 Change of EPT modules involved (e.g., robot moves wafer, chamber processes wafer)

 Change in task type (e.g., purge recipe followed by production recipe)

NOTE 1: It is not practical for equipment to define tasks or modules at an indefinite level of detail. It is therefore recommended

that in each instance for which the material involved, the EPT modules involved, and the task types are all constant, events for

only one task should be reported. Any further breakdown is not required for EPT compliance. EPT places no limitations on

supplemental event reporting within any task. However, these supplemental events should not be reported as EPT events.

9 EPT State Model

9.1 This section defines the basic Equipment Performance Tracking State Model, which is applied to the equipment

and its EPT modules.

9.2 EPT State Model Requirements

9.2.1 The EPT state model is intended to capture the different states of the equipment and its EPT modules from an

operational point of view:

 EPT module busy executing a task.

 EPT module blocked from executing a task.