Dilip Gopi and Roland Schelasin Industrial Engineering, Texas Instruments, Maine

Talk TitleSpeaker NameSpeaker Title

Using Scheduling For Constraint Management in Semiconductor Manufacturing

Dilip Gopi and Roland Schelasin

Industrial Engineering, Texas Instruments, Maine

Outline

• Wafer Fabrication Process Overview

• TI Maine Fab Overview

• Scheduling Methodology Overview

• Problem Statement

• Rule Definitions

• Benefits

2

© 2014 Texas Instruments Incorporated

TI Maine Fab Overview

3


Wafer Fabrication Process Overview

4

Clifford L. HendersonClifford L. HendersonClifford L. Henderson

Used with Permission from Clifford L. Henderson, GA Tech [email protected] 404 385-0525

Wafer Fab

Re-Entrant Flow


mailto:[email protected]

TI Maine – Location

FreisingFFAB

DallasDFABDMOS5DMOS6SFABDHC RFABDBump

AguascalientesTMX

BaguioBaguio

MalaysiaTIMTIEM

TaipeiTITL

MihoMiho Fab

HijiHiji FabHiji A/T

StaffordHFABHBump

Color ManagementFabAssembly & TestBump

PampangaClark

AizuAizu FabChengdu

Chengdu Fab

GreenockGFAB

PortlandMFAB


MFAB – Maine – The Way Life Should Be!

Portland


TI Maine - Fab Overview

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• 200mm SMIF w/Intercell Transport/Stockers

• 27 Technologies, 130-1500nm, 16-48 Masks

• 50,000 Reticles (10,000 In Fab)

• 700 Active Products

• 75k sq. ft. Clean Room

• In-House MES

• 7 x 24 Manufacturing with 4 Shifts

• Electronic Run Cards (STS): Real Time Wafer Level Tracking

• Intelligent Stockers for Lot Dispatch

• Automatic Recipe Select/Downloading

• Automated “Feed Forward” Adjustment for Advanced Process Control


TI Maine – Mix and Capacity Overview

• Approximate Wafer Starts Mix• 54% 350nm CMOS, Avg. 26 Patterns• 26% 1500-130nm BiCMOS, 16-48 Patterns• 20% 180nm CMOS, Avg. 31 Patterns

• Bottle Necks• Design – Photo• Tactical – EPI, Etch (Metal, Oxide), CMP, Diffusion (Clox)

– Technology + Process Module Sub-Capacities

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Scheduling Overview• Scheduling is an important tool for

manufacturing and engineering since it can have a major impact on the productivity of a process.

• Helps minimize– Production Time– Costs

by explicitly telling the manufacturing specialists what to run on which equipment.

• Production scheduling aims to maximize efficiency of the operation

• The methodology presented uses scheduling theory based on point allocation to dictate lot-to-entity allocation and visualization for one of the constraint modules in the factory

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Problem Statement• 6 Chamber States (setup condition)

with 35 active production recipes

• In-flexibility to run everywhere based on,– Hardware– Gas restrictions– Recipe qualification on tools

• Chamber conditioning & test runs needed when switching states

• Inability to meet required productive hours results in cycle time losses

Chamber states are defined based on the gas configuration used for Production

Layer Chamber State

EPI01 EPI02 EPI03 EPI04 EPI05 EPI06States

QualifiedCollector As Lo 1Emitter As Hi 1

Collector As Lo 1Collector Boron 1Collector As Lo 1Collector As Lo 1Collector As Lo 2Collector P 2Collector P 2Collector P 2Collector P 2

N Base Base 2P Base Base 2P Base Base 2Emitter Base 2

N Collector P 2Collector As Lo 2

N Base Base 3Emitter As Hi 3P Base Base 3N Base Base 3

P Collector Boron 3N Base Base 4

Collector Boron 4Collector Boron 4Collector Boron 4Collector P 5Collector P 5Collector P 5Collector Boron 5Collector Boron 5Collector Boron 5

Released Hardware In Qual Not Qual'd As Hi Restrict


Problem Statement (Contd.)237

17 12 933 27 26 19 18 11

75

10 70

50

100

150

200

250

Dow

n M

aint

enan

ce

Leak

up P

M

Cham

ber S

tate

Cha

nge

Dow

n Pr

oces

s

Wait

for Q

ual D

ata

Idle

- W

ait fo

r WIP

Wait

for L

ot C

lean

Dow

n Pr

oces

s Idle

Idle

- Do

wn

Qual

Runn

ing

Qual

Pass

ing L

ane

Run

PCRC

Qua

l

Down Idle Qual

Hour

s/W

eek

Average Hours/Week

0

20

40

60

80

100

120

12/2

0/12

12/2

1/12

12/2

2/12

12/2

3/12

12/2

4/12

12/2

5/12

12/2

6/12

12/2

7/12

12/2

8/12

12/2

9/12

12/3

0/12

12/3

1/12

1/1/

13

1/2/

13

1/3/

13

1/4/

13

1/5/

13

1/6/

13

1/7/

13

1/8/

13

1/9/

13

3/14

/13

3/15

/13

3/13

/13

3/12

/13

3/11

/13

3/10

/13

3/9/

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Week 1 Week 2 Week 3 Week 4

Prod

ucti

ve H

ours

EPI01 EPI02 EPI03 EPI04 EPI05 EPI06T o o l

Week Date

Sum of Time (Hrs)

E10 State

Goal

Productive Hours/Day

Components of Chamber State ChangeRe-Measure

( 6 Months Data)

Equivalent Loss of 1 Tool due to


Proposed Model – Tools by State

• Reduce Chamber State Changes

• Eliminate associated Idle time with State Changes

• Use Passing Lanes to keep recipes Qualified

• Each Tool to have a Primary and Backup State

• EPI Scheduler to define State Changes based on WIP and Look ahead functions

• Reduce downtime associated with state changes

0.0

1.0

2.0

3.0

4.0

As Hi As Lo Base Boron P Hi P Lo

# of

Too

ls

4QCY12 1QCY13 2QCY13 # of Tools Assigned

ToolPrimary

StateSecondary

StateEPI01 As Lo BoronEPI02 As Hi BaseEPI03 Base Boron/PEPI04 Base As Lo /PEPI05 Boron BaseEPI06 Base As Hi

Preferred Tool Model


What is a WIP Scheduler?

• The WIP Scheduler is used to schedule a lot to be loaded into the tool

• The WIP Scheduler uses a set of rules that have been set up for each entity type

• The WIP Scheduler schedules a run by using the rules and other factors on each tool

• The WIP Scheduler and Dispatch are Different!– Dispatch only shows work, and the order is based on dispatching rules:

• Slack time• Priority lot (Hot, Hand carry, etc.)

– The WIP Scheduler sees what can run on a tool and determines what lot or group of lots (batch) should run next based on the rules

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Rule Definitions

• Points are assigned for each rule (Low, Med, High)

• Lot-based Rules

– Priority, Lateness, Static

• Lot / Entity Rules

– “Cost” of changing Chamber State

– How many tools can run the Recipe right now?

• Fewer tools means MORE points

– MTTD consideration for batches with inspectable lots


Maximization Function

Where Rules are defined based on,

• Lot Priority

• Lot Lateness

• Lot Slack Time

• Lot Inspection

• Tool Chamber State

• Tool Count

• Tool Ready

• Tool State, etc.

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Max Z = Rule1 + Rule 2 + Rule 3 + Rule…


EPI Rule Set

Type Name Min Points

Mid Points

Max Points Min Text Mid Text Max Text

BATCH PRIORITY 0 300 500 no priority Medium Priority High Priority Lot

BATCH LATENESS 100 200 300 3 days late 7 days late >10 days late or push it

BATCH STATIC 100 300 500 24 - 48 hours 48-72 hours >72 hours

BATCH STATIC_HRS 0 0 1 hours static

BATCH INSPECTION 100 300 500 Inspectable 50-125 Inspectable 125-500 Inspectable >500

ENTITY TOOL_COUNT 0 0 300 3 tools 2 tools 1 tool

ENTITY QUAL EXPIRATION 100 300 500 >7-14 days 2-7 days <2 days

ENTITY RUNNABLE 0 300 500 Cannot Run Allowed but must Qual Can run Now

ENTITY STATE_CHANGE 0 0 0 Value from table


State Change Table

To

From

State As Hi As Lo Base Boron P Hi P LoAs Hi 5000 100 10000 5000 5000As Lo 0 100 100 100 100Base 100 1000 100 100 100

Boron 0 100 100 100 100P Hi 100 100 0 100 0P Lo 100 100 0 100 0

Risk Levels

0 Just do it.100 Can be handled with standard prep recipe (hours)

1000 Extended chamber prep time and qualification (days)10000 Don't do it.


Scheduler Breakdown

Projected time when tool will finish current

lot(s)

CurrentState

Points Score based on Rule

Set


Benefits

• 34% increase in Productive Hours

• Chamber State Dedication Helped,– Increased Availability– Increased Utilization– Increased Labor Productivity– Reduced number of State

Changes– Reduced Quals– Gas Savings

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Scheduler Online


Benefits (Contd.)

• Empowerment to the shop floor

• Engineering Productivity Improvement

• Gave the floor a better visibility of what needed to run next

• Look ahead of when the next lots are needed on what tool

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Q&A

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Documents

Dilip Gopi and Roland Schelasin Industrial Engineering, Texas Instruments, Maine