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Managing Multi-chamber Tool Productivity

OR Seminar PresentationTeacher: Pros. 陳茂生 , Pros. 阮約翰Student: 937807 張幼蘭 2005/4/21

Bruce Auches, Gulsher Grewal, Peter Silverman

Intel Corporation Santa Clara, Ca.

 This paper appears in: Advanced Semiconductor Manufacturing Conference and Workshop, 1995. ASMC 95 Proceedings. IEEE/SEMI 1995

Publication Date: 13-15 Nov. 1995 Page(s): 240 – 247

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Introduction

Because the operational economic benefits, Multi-chamber tools became popular nearly in a decade.

Used in Thin-film, Etching,Testing fields.

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Measurements of Productivity Run Rate: output wafer per hour (wph) Run/PM Cycle

Motivation: help tool user to make decision of repairing or ignoring failure chamber that maximize productivity.

Various run scenarios

PM

PM Time

Run/PM cycle

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Delimit Problem Boundary (1/3)

Focus on parallel configuration.

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Delimit Problem Boundary (2/3)

Parallel processing mode can run by other available chambers.

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Delimit Problem Boundary (3/3)

Scheduled PM is triggered by fixed processing wafer quantity. Quantity base PM: metal deposition,

poly etching… Time base PM: photo exposure

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Responses of Unexpected Chamber Failure Incident (1/3)

Full Cluster Operation (FCO): take down tool completely to repair failure chamber.

Necessary if: Central component fail Cannot repair while the rest tool run

Full Run

Full Run

Take down to repair

Chamber Failure

PM

PM Time

Run/PM cycle

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Responses of Unexpected Chamber Failure Incident (2/3)

Partial Cluster Operation (PCO): defer to repair failure chamber and keep good chambers running until next PM.

Necessary if: Cannot repair while the rest tool run

Full Run

Defer repair and keep Partial Run

Chamber Failure

PM

PM Time

Run/PM cycle

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Responses of Unexpected Chamber Failure Incident (3/3)

Run/Repair Operation (RRO): repair failure chamber while the rest tool runs.

May or may not be feasible depending on safety issue and failure position.

Full Run

Full Run

Repair with Partial Run

Chamber Failure

PM

PM Time

Run/PM cycle

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Fixed Variables (1/2)

Tool Run Rate Full Cluster Run Rate (FCRR) Partial Cluster Run Rate (PCRR) As FCRR decreases, FCO is favored.

Mean Wafers between PM (MWBPM) Visiting wafer quantity between PM for

each chamber. As MWBPM increases, FCO is favored.

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Fixed Variables (2/2)

Major PM Duration (tPM) As long as one chamber finished

MWBPM wafers, major PM is triggered.

As tPM decreases, FCO is favored.

Number of Process Modules (n) Count “Parallel Path” As n decreases, FCO is favored.

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Failure-dependent Variables

Time to Repair (MTTR) Duration of repairing failure chambers As MTTR decreases, FCO is favored.

Wafer Count (%F * MWBPM) Processed wafers quantity before

chamber failed. As %F increases, FCO is favored.

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Output Evaluation Formulas(1/4)

W = number of wafers processed in a complete “run/PM” cycle

C = total time in a “run/PM” cycle Output = W/C Higher output is favored

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Output Evaluation Formulas(2/4)

FCO WFC = MWBPM * n CFC = tBFFC + MTTR + tAFFC + tPM

tBFFC: Time before failure

tBFFC = (%F * MWBPM * n) / FCRR tAFFC: Time after failure

tAFFC = ( ( 1 - %F ) * MWBPM * n) / FCRR

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Output Evaluation Formulas(3/4)

PCO WPC = WBFPC + WAFPC

WBFPC = MWBPM * n * %F WAFPC = MWBPM * ( n–1 ) * ( 1- %F ),

assume one chamber/path fail for example.

CFC = tBFFC + tAFFC + tPM

tBFFC = (%F * MWBPM * n) / FCRR tAFFC = ( ( 1 - %F ) * MWBPM * (n-1) ) /

PCRR

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Output Evaluation Formulas(4/4)

RRO WRR = WBFRR + WDFRR + WAFRR

WBFRR = MWBPM * n * %F WDFRR = MTTR * PCRR

If MTTR is long enough that other good chambers/paths reach PM, then WDFRR = WAFPC.

WAFRR = [ MWBPM - WBFRR/n - WDFRR/(n-1) ] * n

CFC = tBFRR + MTTR + tAFRR + tPM

tBFRR = (%F * MWBPM * n) / FCRR tAFRR = WAFRR / FCRR

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Example (1/3)

Values for variables: n = 2 FCRR = 20 wph (wafers per hour) PCRR = 10 wph tPM = 10 hr (hours) MWBPM = 500 wafers per

chamber/path %F = 20% MTTR = 10 hr

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Example (2/3)

Output calculation: FCO: 1000 wafers / 70 hr = 14.3 wph PCO: 600 wafers / 60 hr = 10.0 wph RRO: 900 wafers / 60 hr = 15.0 wph

RRO is the best decision if it is feasible; otherwise, FCO is suggested to choose.

Deferring repair would cause 30% of FCO output loss and 50% of RRO output loss.

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Example (3/3)

RRO Total

Time (hr) 0~10 10~20 20~30 30~40 40~50 50~60 60

Tool State Full Run Repair withPartial Run

Full Run Full Run Full Run PM

Run Rate 20 10 20 20 20 0Wafer Count 200 100 200 200 200 0 900

Output = 15.0

FCO Total

Time (hr) 0~10 10~20 20~30 30~40 40~50 50~60 60~70 70

Tool State Full Run Take down toRepair

Full Run Full Run Full Run Full Run PM

Run Rate 20 0 20 20 20 20 0Wafer Count 200 100 200 200 200 200 0 1000

Output = 14.3

PCO Total

Time (hr) 0~10 10~20 20~30 30~40 40~50 50~60 60Tool State Full Run Partial Run Partial Run Partial Run Partial Run PMRun Rate 20 10 10 10 10 0

Wafer Count 200 100 100 100 100 0 600Output = 10.0

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Sensitivity Analysis (1/4)

At most time, the RRO is the best strategy; PCO become the best when the MTTF is longer than the time of processing (1-%F) wafers. In previous example, the “break-even

point” of RRO and PCO is at %F = 80%; FCO and PCO is at 72%.

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Sensitivity Analysis (2/4)

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Sensitivity Analysis (3/4)

Longer MTTR or later failure timing (bigger %F) lead to choose PCO; or else, lead to choose FCO. Using the data in previous example, it

can be plot a “break-even curve” of FCO and PCO corresponding to %F and MTTF. Above the curve PCO should be employed; below the curve FCO should be employed.

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Sensitivity Analysis (4/4)

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Conclusion Tools should be designed to enable

the RRO where successfully maximize output in most cases.

PCO availability should be minimized in most cases. The root causes of the premature failures should be aggressively sought out and fixed.

If RRO is not feasible, tool user should calculate the “break-even curve” to help make decision more quickly.

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Further Study

Multiple multi-chamber tool repair decision process

Other site unbalance problems