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SEMI E10-0304 E © SEMI 1986, 2004 18 RELATED INFORMATION 1 MULTI-PATH CLUSTER TOOL RAM METRICS NOTICE : This rel ated infor mation is not an offici al part of SEMI E10 an d was derived from work done by t he SEMI NA Clus…

SEMI E10-0304

Figure A2-1

Duane Plot of CUM MTBF

vs. Time

Trend

o Trend

Sections 8.1-8.3/Appendix 2

Estimate the achieved

MTBF

at the end of

the period

Sections 6.2.1-6.2.2

Use standard MTBF

definition

Section 7.6/Appendix 1

Compute confidence

bounds for MTBF

Analyze the data for trends

Duane Plots

Trend Test

Section 8.3/Appendix 2

Fit AMSAA model

Figure A2-2

Flow Chart for Reliability Data Analysis

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SEMI E10-0304

RELATED INFORMATION 1

MULTI-PATH CLUSTER TOOL RAM METRICS

NOTICE: This related information is not an official part of SEMI E10 and was derived from work done by the

SEMI NA Cluster Tool RAM Metrics Task Force. This related information was approved for publication by full

letter ballot on October 15, 2003.

R1-1 Introduction

R1-1.1 This related information presents tracking

requirements and standard metrics for evaluating multi-

path cluster tool reliability, availability, and

maintainability (RAM) performance. The metrics in

the main body of SEMI E10 apply to non-cluster or

single-path cluster tools and individual modules in a

straightforward manner. While these entities are either

entirely “up” (i.e., in one of the SEMI E10 uptime

states) or entirely “down” (i.e., in one of the SEMI E10

downtime states), multi-path cluster tools may still be

capable of processing with some modules in an

unscheduled downtime state. Furthermore, the effect of

module unscheduled downtime on multi-path cluster

tool performance depends on the specific multi-path

cluster tool configuration and the combination of

modules in an unscheduled downtime state at each

point in time.

R1-1.2 Because module performance provides a

sufficient lowest common denominator for evaluating

multi-path cluster tool performance, all metrics in this

related information are calculated as functions of

module-level data only. Specific module tracking

requirements are presented. The metrics, Total Failure

Rate (TFR) and Cluster-Tool Mean Time to Repair

(MTTR

), provide simple evaluations of aggregate

module reliability and maintainability.

R1-1.3 Other metrics are based on the specific

combinations of modules and process paths, defined

here as process flows.

R1-1.3.1 A process path is a specific set of modules

for which each module is unique and has no alternative

modules.

R1-1.3.2 A process flow is a defined set of modules

that is used to achieve a process, where any multi-path

cluster tool may have one or more such process flows.

A process flow may include alternative modules at one

or more steps of the process. A process flow may

therefore contain one or many process paths.

R1-1.4 A method of temporal mapping, defined in this

related information, is used to generate a history of

process flow and multi-path cluster tool states from

individual module states. Multi-path cluster tool

availability is then evaluated as the aggregate process

flow availability. Multi-path cluster tool reliability is

evaluated as the expected, or mean, productive time

between all process flows being in unscheduled

downtime.

R1-2 Module Tracking Requirements

R1-2.1 Multi-path cluster tool metrics require the

tracking of SEMI E10 state data from all of the modules

that impact the RAM or productivity of a multi-path

cluster tool or its process flows. This set of modules

includes processing and non-processing modules.

R1-2.1.1 processing module — an indivisible

production entity within an equipment system, e.g., a

processing chamber or station within a cluster tool.

(SEMI E79)

R1-2.1.2 non-processing module — an equipment

entity that supports the movement or conditioning of

units through the system, such as, robotic handler,

load/unload lock, pre-aligner.

R1-2.2 Multi-path cluster tool metrics require tracking

at the module level of at least productive states,

unscheduled downtime states, scheduled downtime

states, and other neutral states that are not in the first

three categories. Tracking of these states at the level of

the multi-path cluster tool as a whole is insufficient for

accurate evaluation of performance. Specific

requirements for tracking these states at the module

level, as well as requirements for handling the other

SEMI E10 states, are presented here.

R1-2.2.1 Productive state shall be tracked for each

module. For process modules, the productive time shall

include time for active loading and unloading of the

process module. Waiting times or inactive times,

including waiting for load, waiting for unload, and

process suspend times shall be specifically excluded

from productive time. Times for heating, cooling,

purging, cleaning, etc., that are specified as part of

process recipes shall be tracked as productive time.

However, similar times that are not specified as part of

process recipes shall be specifically excluded from

productive time.

NOTE 1: Productive state events may be derived from SEMI

E58 (ARAMS) state change data or the SEMI E116 (EPT)

module BUSY state events where the module or whole multi-

path cluster tool is known to be in a “manufacturing” state

and the SEMI E116 task type is either “Process” or

“Support.”

SEMI E10-0304

R1-2.2.2 Unscheduled downtime state shall be tracked

for each module. Tracking of unscheduled downtime

state for the multi-path cluster tool as a whole is not

sufficient. A module cannot be in productive and

unscheduled downtime states at the same time. Each

contiguous instance of unscheduled downtime state for

a module is a module failure. Subsequent substate

events within the same instance of unscheduled

downtime state shall not to be counted as additional

failures.

R1-2.2.3 Scheduled downtime state shall be tracked for

each module. Tracking of scheduled downtime state

for the multi-path cluster tool as a whole is not

sufficient. A module cannot be in productive and

scheduled downtime states at the same time. Instances

of scheduled downtime shall not to be counted as

failures.

R1-2.2.4 Time in standby and engineering states shall

not be considered as either productive time, scheduled

downtime, or unscheduled downtime at the module

level. For the purpose of tracking multi-path cluster

tool states and calculating multi-path cluster tool and

process flow metrics, modules in these states are

considered as being in a neutral state.

R1-2.2.5 Non-scheduled time that is tracked for the

multi-path cluster tool as a whole is omitted from

operations time in calculating multi-path cluster tool

and process flow RAM metrics, as it is with the other

SEMI E10 metrics from the main body of the

specification. Non-scheduled time that is allocated to

some modules but not other modules, if any, shall be

handled differently, as follows.

R1-2.2.5.1 For new modules under installation that

have not yet been used for their intended function, those

modules shall be considered as non-existent in the

cluster-tool configuration.

R1-2.2.5.2 For installed modules that have been used,

non-scheduled time state shall be treated as a neutral

state.

R1-2.3 To calculate these metrics, an observation

period shall be defined and agreed upon by the user

and/or the supplier. Section A1-1.3 provides some

guidance on establishing the observation period time

needed to demonstrate a desired MTBF

at a given

confidence level.

R1-2.3.1 observation period time — elapsed calendar

time (e.g., weeks, months, quarters) observing and

tracking tool performance. No allowance is made for

the number of modules in a cluster tool.

R1-3 Total Failure Rate and Cluster-Tool Mean

Time to Repair

R1-3.1 Total Failure Rate (TFR) — total count of

module-level failure onsets, tracked according to the

requirements in Section R1-2, divided by the

observation period time. This metric characterizes the

frequency of repairs where failures on separate modules

are presumed to require independent repair actions.

TFR is an indicator of reliability and maintainability.

TFR is defined as:

TFR =

all modules

count of module failure onset events

observation

eriod time

NOTE 2: For different multi-path cluster tools with

comparable module failure rates, a multi-path cluster tool

with fewer modules is expected to have better performance

according to this metric than one with more modules.

However, the multi-path cluster tool with more modules may

have a better aggregate intended process flow uptime

(Uptime

CT-IPF

), as defined in Section R1-7.3.

R1-3.2 Cluster-Tool Mean Time to Repair (MTTR

)

— mean time to correct a module-level failure and

return the module to a condition where it can perform

its intended function; the sum of all repair time on all

modules (elapsed module time, not necessarily total

work-hours) incurred during a specified observation

period time (including equipment and process test time,

but not including maintenance delay downtime),

divided by the total number of failure onset events

during that period.

TTR

all modules

repair time

all modules

count of module failure onset events

NOTE 3: This is the same equation as MTTR for non-cluster

and single-path cluster tools. However, because a multi-path

cluster-tool may have repairs occurring simultaneously, the

sum of repair time is not constrained to the duration of the

observation period.

R1-3.3 For any module, a failure onset event is the first

chronological event of a contiguous instance of

unscheduled downtime. To ensure that over multiple

observation periods, neither failure onset events nor

repair time is ever double-counted, the following rules

shall be followed.

R1-3.3.1 Failure onset events that occur during the

observation period are counted in TFR and MTTR

regardless of when those failures are resolved.

R1-3.3.2 Failure onset events that occur before the

observation period are not counted in TFR and

MTTR

, even if those failures are not resolved until

during or after the observation period.