progress on euv industrialization twinscan - asml holding nv

ASML’s customer magazine | 2012 Issue 1

Progress on EUV Industrialization

TWINSCAN NXT: A thoroughbred workhorse

A bright future for ASML’s refurbished tools

2

images | Colofon

Editorial Board

Lucas van Grinsven, Peter Jenkins

Managing Editor

Ryan Young

Contributing Writers

Rudy Peeters, Stuart Young, Ton van Niftrik,

Jan-Evert van de Wetering, Robert Kazinczi,

Rob van Keulen, Steven van Heek

Circulation

Emily Leung, Michael Pullen, Shirley Wijtman

For more information, please see:

www.asml.com/images

© 2012, ASML Holding BV

ASML, ASM Lithography, TWINSCAN, PAS 5500,

PAS 5000, SA 5200, ATHENA, QUASAR, IRIS, ILIAS,

FOCAL, Micralign, Micrascan, 3DAlign, 2DStitching,

3DMetrology, Brion Technologies, LithoServer,

LithoGuide, Scattering Bars, LithoCruiser, Tachyon

2.0, Tachyon RDI, Tachyon LMC, Tachyon OPC+,

LithoCool, AGILE, ImageTuner, EFESE, Feature Scan,

T-ReCS and the ASML logo are trademarks of ASML

Holding N.V. or of affiliate companies. The trademarks

may be used either alone or in combination with

a further product designation. Starlith, AERIAL,

and AERIAL II are trademarks of Carl Zeiss. TEL is

a trademark of Tokyo Electron Limited. Sun, Sun

Microsystems, the Sun Logo, iForce, Solaris, and the

Java logo are trademarks or registered trademarks of

Sun Microsystems, Inc. in the United States and other

countries. Bayon is a trademark of Kureha Chemical

Industry Co. Ltd. Nothing in this publication is intended

to make representations with regard to whether any

trademark is registered or to suggest that any sign

other than those mentioned should not be considered

to be a trademark of ASML or of any third party.

ASML lithography systems are Class 1 laser products.

6 10 163 Editor’s note

4 Product development with

EUV starts rolling

6 Tomorrow’s CDU performance

at today’s metrology effort

10 Always top performance

at full productivity

16 TWINSCAN NXT

a thoroughbred workhorse

20 A bright future for ASML’s

refurbished tools

3

ASML Images, 2012 Issue 1

Editor’s note

The headlines from SPIE Advanced

Lithography focused on the current

industrialization of EUV, overshadowing

the exciting and equally impressive

results in immersion lithography and

computational lithography. ASML sees

equally important roles for all of these

technologies in the coming years and

presented on all three technology streams.

ASML is working both to industrialize

EUV, and to extend the capabilities of

Immersion, as most of our customers are

planning parallel process developments.

In both cases the proven advantages

of Holistic Lithography provide more

comprehensive customer value in the

effort to perpetuate Moore’s Law.

Let’s start with EUV. The number of

papers, panels and presentations at SPIE

AL demonstrate that the industrialization

of EUV is in full swing. All six of ASML’s

NXE:3100 systems are now installed

at customer sites, are imaging wafers,

and cycles of EUV process learning

are accelerating. The first NXE:3300 is

assembled in Veldhoven and NXE:3300

shipments will begin later this year.

Our expectation is that EUV adoption into

manufacturing will be gradual, and that

EUV and immersion will cohabitate for a

period. Because of this, we are continuing

with innovation on our immersion platform

concurrent with the development of the

EUV platform itself.

The NXT:1950i is the industry workhorse

for leading-edge litho. More than 120

systems have been shipped to memory,

logic and foundry customers, and

throughput numbers above 4,100 wafers

per day have been achieved. To drive

the performance of this system even

further, upgrades in imaging, overlay

and productivity are all underway.

On the Holistic Litho front, new products are

being added. BaseLiner version 1.5 will be

released later this year providing scanner

overlay-related rework reduced by half and

matched-machine overlay improvements

of around 40%. CDU Optimizer improves

on-product CDU performance by over 30%

and implements higher-resolution dose

corrections and CD metrology without

increasing metrology cost. And, Tachyon

FMO (Flexible Mask Optimization) enables

the seamless use of multiple Optical

Proximity Correction (OPC) techniques in

a single mask tapeout, permitting the use

of advanced and computationally intensive

OPC in those local areas where they provide

maximum benefit.

As you may have seen at SPIE AL and as

you will read in this edition of Images,

ASML is working to provide a complete

product portfolio to meet the needs of our

customers, and do so while providing the

highest value.

Regards,

Ryan Young

Multiple and Complimentary Litho StreamsBy Ryan Young, Senior Manager Communications

4

240-nm depth of focus (DoF) and

exposure latitudes of 18% for dense

lines or 14% for isolated lines.

Moreover, using the NXE:3100’s off-axis

illumination capability, customers have

achieved a resolution of 16 nm with

a conventional chemically amplified

photoresist. Importantly, several suppliers

are now offering photoresists capable

of sub-18-nm imaging, which supports

our roadmap for future NXE generations.

However, so far sub-18-nm images have

only been exposed with doses above 30

mJ/cm2, and further work is required to

improve resist sensitivity to 15 mJ/cm2.

Of course, real devices aren’t made of

just line/space patterns. And a particular

advantage of EUV lithography is the

Product development with EUV starts rollingBy Rudy Peeters and Stuart Young, Senior Product Managers EUV

With the sixth and final TWINSCAN

NXE:3100 pre-production system now

installed at a customer, extreme ultraviolet

(EUV) lithography is taking the next step in

its journey towards volume manufacturing.

NXE:3100 customers are moving from

the early learning stage into device

development.

Unrivalled imaging

A key driver for developing EUV lithography

is its ability to print extremely small

features in a single exposure. This ability

is evidenced by recent customer data on

the unrivalled imaging performance of the

TWINSCAN NXE:3100.

For example, at the system’s specified

resolution of 27 nm, customers have

reported process windows with a

Abstract | EUV lithography is moving to

the next stage: product development.

With the last of our six TWINSCAN NXE:3100

systems now installed, customers have

exposed thousands of R&D wafers –

including the first ever working devices

produced with the NXE:3100. At the

same time, ASML has improved system

performance in many areas and, together

with Cymer, has improved source power

and availability, increasing system outputs.

Moreover, we recently recorded first light

in an NXE:3300B – our next-generation

EUV system for volume production.

5


possibility of imaging complex 2D patterns

at small feature sizes in a single exposure

without stringent design limitations. Again

customer data shows that this possibility

is a reality on the NXE:3100, with the

system’s imaging performance proven

for all relevant device applications.

Beyond imaging

ASML and its customers have also been

making important progress in other

key areas that are vital for making EUV

production ready. Dedicated chuck overlay

(DCO) below 2 nm (with practically no

difference in performance at the edge and

center of the wafer) has been reported by

multiple customers, albeit at a reduced

scan speed. This is well beyond the

system’s specified DCO of 4 nm, and work

to maintain this performance at full scan

speed is ongoing.

Matched machine overlay between the

NXE:3100 and the TWINSCAN NXT:1950i

has been pushed to 4.5 nm while on-

product overlay below 7 nm has been

achieved. Again, both these numbers are

well within specification. In addition, the

installed NXE:3100s have been exhibiting

good overlay stability over periods of

several months.

As a result of these developments,

customers are seeing the potential the

NXE:3100 offers for product development.

The majority of customers have started

exposing R&D wafers for device

development, and thousands of wafers have

now been exposed on NXE:3100 systems

worldwide. And recently, multiple customers

have created working devices using the

NXE:3100 to expose critical layers.

Source developments

Of course, source performance remains a

critical area of interest for EUV lithography.

Here too there have been recent encouraging

developments. At the end of 2011, ASML

and its source partner Cymer released

a source module upgrade that increased

source power and stability, tripling

the NXE:3100’s wafer output. Another

upgrade was implemented at the start

of 2012, further doubling the wafer output

capability to over 300 wafers per week.

Customers have created

working devices using

the NX:3100

These upgrades represent significant

increases in the number of wafers per

week that NXE:3100 systems can deliver.

However, while these system outputs

support the R&D work required to prepare

for high-volume manufacturing, they are

still below the levels needed for production

itself. Hence ASML and Cymer are

engaged in a concerted and collaborative

effort to accelerate source development.

Roadmap to the future

The TWINSCAN NXE:3100 is a pre-

production tool designed to let customers

learn about EUV lithography and carry out

process and product development in this

emerging technology. While there are still

developments to be made, this is a role

the NXE:3100 is now filling.

ASML’s roadmap to volume manufacturing

with EUV includes a number of generations

of production systems. The first of these

is the TWINSCAN NXE:3300B, an

NA = 0.33 scanner with specified resolution

of 22 nm. System assembly has begun at

our dedicated EUV facility in Veldhoven,

The Netherlands. The first fully assembled

system is now ready for integration

testing and we recently achieved first

light in an NXE:3300B. Coming soon

after the announcement of the first ever

working devices from an NXE:3100, this

development is further evidence of EUV

lithography’s progress.

Flash staggered contact layerBitline pitch = 44 nm (1:1.2)

CH pitch = 74.4 nm

Sub 16 nm node �SRAM Contact Hole

0.038µm2 bit cell-size, �hp 30/32 nm

16nm dense lines 27 nm Gate Layer Flash

Sub 16 nm node �SRAM metal-1

0.038µm2 bit cell-size, hp 30/32 nm

30 nm Brickwall DRAM

X=1.1nm y=0.7nm X=1.0nm y=0.9nm X=0.9nm y=1.0nm



System A

System B

System C

NXE: 3100 imaging performance proven for customer use cases

Dedicated chuck overlay (DCO) of <2 nm has be achieved on multiple NXE:3100 systems

6

Tomorrow’s CDU performance at today’s metrology effortBy Ton van Niftrik, Product Manager

The drive for feature shrink necessitates

a similar drive to improve on-product

critical dimension uniformity (CDU)

performance, to maintain yields and

profitability at new technology nodes.

Many factors contribute to your on-

product CDU budget, including the

mask, scanner, track and off-scanner

process steps such as etching.

Today’s lithography systems have the

flexibility to compensate for all these

Abstract | CDU Optimizer is a new system

enhancement product from ASML that

helps you achieve the on-product CDU

performance necessary for upcoming

technology nodes. By using dose correction

recipes to compensate for CDU fingerprints

arising throughout the semiconductor

manufacturing process, it can improve

on-product CDU by more than 30%. It is

designed for easy implementation in the fab,

and allows higher-resolution corrections for

future nodes at today’s metrology effort.

contributions. And ASML offers a range

of system enhancement products to

harness that flexibility, and improve

on-product CDU performance. What’s

more, we have a roadmap in place to

ensure new solutions become available

at the right time for your on-product CDU

performance to meet the requirements

of future technology nodes.

The latest product from this roadmap

is CDU Optimizer. Following on from the

0

1

2

3

4

5

2011 2012 2013 2014 2015 2016 2017 2018

CD

U 3

s (n

m)

Year of Production

DRAMFlashMPU

ITRS CDU roadmap

7


successful DoseMapper, CDU Optimizer

calculates and applies dose corrections

to compensate for intrafield, interfield

and wafer-to-wafer CDU fingerprints

arising anywhere in the semiconductor

manufacturing process. Compared to

DoseMapper, it offers significant CDU

performance improvements for the

same metrology effort.

More freedom to correct

As with DoseMapper, dose corrections

are calculated from production wafer

metrology data and applied to subsequent

wafers through the scanner’s Unicom XL

and Dosicom actuators. However, CDU

Optimizer offers much more freedom in

controlling these actuators, allowing more

precise corrections to be applied.

Improve on-product CDU

performance by over 30%

For example, CDU Optimizer can control

each of the 56 fingers in the Unicom

module individually to create completely

freeform Unicom profiles. It also relaxes

the Dosicom constraints to permit steeper

dose gradients. These two features

improve intrafield CDU in the slit and scan

directions respectively. CDU Optimizer

also allows a different Unicom profile

to be used for each field on a wafer,

reducing CD variations between fields.

In addition, CDU Optimizer lets you apply

different sets of corrections to different

wafers in the same lot. Such “wafer-level”

corrections can be used to compensate

for wafer-to-wafer variations caused, for

example, by processing wafers in different

chambers of the litho cell’s etcher.

Raw data

DoseMapper

(-/-50% in this improvement simulation

based on data)

slit position [mm] 0 10 20 -10 -20

Slit profile

DoseMapper 6 UNICOM groups

DoseMapper

(-/-60% in this improvement

simulation based on data)

CDU Optimizer UNICOM per field

0.5

0.4

0.3

0.2

0.1

0.0

-0.1

0.2

--0.3

-0.4

Correction based on the fingerprints

of etch chamber 1

Correction basedon the average

fingerprint of etch chamber 1 & 2

Correction based on individual

etch chamber fingerprints

35% 55%

Raw data

CD

U 3

s (n

m)

DoseMapper CDU Optimizer

Etch chamber 1Etch chamber 2

Etch chamber 1

Etch chamber 2

CDU Optimizer makes further CDU improvements over DoseMapper

Unicom per field shows best CD control

FreeForm Unicom shows best CD control

8

Reducing the metrology burden

Moving to new technology nodes and

delivering the CDU improvement that

this requires can have a huge impact on

your metrology burden. This is because

achieving better CDU usually means you

must measure more data points per critical

layer, while smaller feature sizes mean

there are more critical layers in a device.

space (S2) and the difference between

them (S1-S2) in a typical spacer process.

In this case, CDU Optimizer enabled a

30% reduction in the 3σ value for the

variation of S1-S2.

A perfect partnership

CDU Optimizer’s ability to determine

the right dose corrections and hence

improve on-product CDU depends

strongly on the quality of metrology data

available. This makes ASML’s YieldStar

metrology tool the perfect metrology

partner for CDU Optimizer.

YieldStar is extremely fast and precise.

Not only does it demonstrate almost

perfect correlation with CD-SEM results

(the current gold standard in fabs),

it has been shown to be significantly

more precise. This improves the ability to

determine process fingerprint, ultimately

resulting in lower CDU. At the same time,

YieldStar is much faster than CD-SEM,

enabling more measurements to be

performed in a production environment

which in turn allows better capture of

process variations (J. Lee et al, SPIE 2012).

Spacer balancing to enable

future nodes

Future technology nodes will employ an

increasing number of double or multiple

patterning layers. A popular choice for

implementing multiple pattering are the

so-called spacer techniques, where a layer

of spacer material is deposited onto the

patterned wafer and etched away so as

to increase the density of features on the

wafer. This introduces two separate feature

spacing parameters: one governed by the

lithography step and one by the spacer step.

To ensure end-product performance, these

two spaces should be as close to equal

as possible. But because they arise from

separate steps, this “spacer balancing”

can be difficult to achieve. However,

CDU Optimizer allows you to use dose

corrections to co-optimize lithography and

process fingerprints. This reduces both

the average difference between the two

spaces and its variation across the wafer –

improving yields and device performance.

For example, figure X shows the variation

in the lithography space (S1), the spacer

018

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22

23

50 100 150 010

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12

13

14

15

50 100 150 0

8

7

6

5

10

11

50 100 150

No dose correction for S1/S2 applied

3s = 2.7nm

S1 (litho) S2 (process) S1 - S2

3s = 1.8nm 3s = 4.0nm

3s = 2.4nm 3s = 1.3nm 3s = 2.6nm

018

19

20

21

22

23

50 100 150 010

11

12

13

14

15

50 100 150 0

8

9

9

7

6

5

10

11

50 100 150

Dose correction for S1/S2 applied

R2 = 0.88

S1-S2 Scat. (nm)

S1-

S2

SEM

(nm

)

-2 -1 0 1 2-3-4

Correlation plot

YieldStar Scatterometry to CD-SEM

correlation plot

Key metric in Spacer Technology, improved by more than 1nm

9


To some extent, YieldStar alone can help

alleviate this problem as its speed – less

than a second per measurement rather

than 2-3 seconds for CD-SEM – helps

reduce metrology cost-of-ownership.

However, even with this improved

metrology throughput, the current way

of working will soon lead to an unfeasible

metrology burden for future nodes.

Consequently, CDU Optimizer employs a

novel approach to dose recipe generation

that greatly reduces the amount of

metrology required, allowing manufacturers

to implement higher-resolution dose

corrections and CD metrology at today’s

cost. This approach separates product

fingerprints (arising from the reticle) and

process fingerprints (coming from etch

or bake steps for instance), enabling

redundant measurements to be identified

and eliminated.

To illustrate this, imagine a hypothetical

fab set up where two reticles are used

to produce the same product, and

wafers can be sent to either of two

etch chambers. In the traditional way of

working, the manufacturer would need to

perform intrafield and interfield metrology

on all four combinations. That means

8 sets of measurements are required.

With CDU Optimizer, the manufacturer

only needs to perform intrafield metrology

for each mask and interfield metrology for

each etch chamber – so just 4 sets of

measurements.

Implement higher-

resolution dose corrections

and CD metrology at

today’s cost

In a real foundry use case, this enables

huge metrology time savings of around

95%. For example, in a typical use

case involving 100 reticles and 5 etch

chambers, CDU optimizer could reduce

metrology time from 350 hours to just 17.

At the same time, the number of send-

ahead wafers is reduced from 500 to 104.

Improving fab economics

CDU Optimizer is designed for maximum

flexibility and cost-effectiveness in

implementation. It includes a tool for

optimizing metrology sampling schemes

and determining the most cost-efficient

solution metrology set-up. It also features

an improved graphical user interface and

allows several automation implementation

possibilities in the fab.

CDU Optimizer is a further example of

how ASML helps you address the drive for

feature shrink through a complete product

portfolio that integrates control, metrology

and computational functionality as well

as the scanner. This integrated offering

helps you to improve on-product CDU

performance by over 30% and enables

the transition to future technology nodes

while keeping overall fab yields and

profitability high.

Context DoseMapper CDU Optimizer

Send ahead wafer

Required measurements

Send ahead wafer

Required measurements

Mask 1, Etcher A Yes Yes

Mask 1, Etcher B Yes Yes

Mask 2, Etcher A Yes Yes

Mask 2, Etcher B Yes No

X Redundant measurement, reduction of metrology & send ahead time

10

Always top performance at full productivityBy Jan-Evert van de Wetering, Product Manager

11


Always top performance at full productivityBy Jan-Evert van de Wetering, Product Manager

Abstract | ASML’s BaseLiner scanner

option ensures stable overlay and focus

performance over long periods of time.

It allows TWINSCAN scanners to operate

within ATP specifications continuously

for a scanner time investment of a few

minutes every three days. With BaseLiner,

you can improve system productivity and

machine overlay matching while reducing

rework to improve your overall output of

good wafers. Moreover, BaseLiner can also

restore fingerprints, helping reduce work

in progress (WIP) qualification time after

machine interventions. BaseLiner turns

engineering time into productive time.

12

Traditional approaches to addressing

drift in volume manufacturing typically

involve re-calibrating the scanner either

after a given period of time or when it

has drifted beyond a pre-defined amount

away from its specified performance.

The frequency between re-calibrations

is a careful economic balance between

reducing yield losses due to drift and

minimizing scanner downtime.

ASML’s BaseLiner scanner option

offers a better way to tackle drift. It

allows TWINSCAN scanners to operate

continually within their ATP specifications

and requires just a few minutes of scanner

time every few days. BaseLiner ensures

overlay and focus stability, improves

scanner matching and increases system

productivity. In short, it turns engineering

time into an increased number of good

The extreme complexity of cutting-

edge lithography systems has made

“drift over time” – the gradual change

in a scanner’s performance over time

- a fact of life. At larger feature sizes,

manufacturing tolerances were bigger

and drift was easily manageable.

However, as features shrink and

tolerances become tighter, the potential

impact drift has on yield has grown.

Customers have

seen scanner

overlay-related

rework halve

Baseliner Server

Baseliner Wafers

Focus and Overlay measurements

YieldStarmetrology

Measure Overlay and FocusFingerprints Periodically

reference current

BaseLiner ‘Loop’ controls overlay and focus to a preferred fingerprint

13


wafers per month a fab can produce, even

when moving to next node. What’s more,

it significantly reduces the amount of time

engineers spend on re-calibration and

qualification of work in progress (WIP)

after a system intervention, freeing up

valuable man-hours for other tasks.

Speed and simplicity

BaseLiner is a software product that

uses an off-line metrology feedback loop

to keep TWINSCAN scanners performing

to a customer-defined baseline.

That baseline is established by exposing

reference wafers and measuring the

scanner’s overlay and focus fingerprints.

Then, by periodically exposing dedicated

BaseLiner wafers, any variations in

those fingerprints can be monitored

and corrections calculated to return

the scanner to its initial performance.

15.0

17.5

12.5

10.0

7.5

6.0

over

lay

X (n

m)

X overlay Chuck 2

9 nm�

(mean) + 3s/Wafer/Uncontrolled Absolute

(mean) + 3s/Wafer/Controlled Absolute

5.5 nm�

5 months

12

10

8

6

4

2

0

12

10

8

6

4

2

0

(nm) (nm)

1 month

4 nm

Overlay XT:1400F matched to NXT:1950i�(chuck 1, x)

2 nm

Upgrade TOP3�and set BaseLine

BaseLiner applied to XT:1400E improves 5-month overlay stability with a factor 2x

BaseLiner applied to XT:1400F with TOP3 matched to NXT: stable and well below 8 nm without overlay

maintenance time

14

The beauty of BaseLiner is that it allows

these periodic checks and corrections

to be carried out with the minimum of

scanner and engineer time. Fingerprints

can be determined by exposing just four

wafers (two per chuck), and these wafers

are measured in an off-line metrology

tool not the scanner itself. So the scanner

can be back producing wafers in just a

few minutes.

Once exposed, the in-resist focus and

overlay fingerprint for the BaseLiner

wafers can be measured using ASML’s

YieldStar 3-in-1 metrology system.

YieldStar is more precise than other

metrology systems, ensuring robust

BaseLiner performance. It is also

much faster, capable of measuring

four BaseLiner wafers in just two hours

compared to five hours for a typical

metrology tool. This means one YieldStar

system can handle the BaseLiner

metrology for a large number of systems

– and still have plenty of capacity for other

offline metrology tasks. For customers

planning ahead, for on-product focus

metrology and even more sophisticated

overlay improving applications, the

integrated YieldStar T-200 metrology will

smoothly take over, making BaseLiner

operation in HVM even easier.

The measured overlay and focus

fingerprints are fed from the YieldStar

metrology system into BaseLiner’s

calculation engine. This sophisticated

software engine compares the scanner’s

current fingerprints with the reference

fingerprint. In addition, because the

engine includes real scanner models,

it can accurately calculate the exposure

corrections required to return the

scanner’s performance back to the

baseline at the push of a button.

Matched-machine overlay to NXT:1950i of less than

8 nm possible on dry ArF scanners

15.0

12.5

10.0

7.5

nm

2 months

Matched�Overlay

Filtered overlay (99.7%)�NXT:1950i matched to 2DE wafer with BaseLiner

3.5 nm�no BaseLiner

2 nm�with BaseLiner

Focus�Uniformity

40

30

20

10

nm

2 months4 months

< 6 nm

No Baseliner With Baseline

Standard

BaseLiner controlled

Major upgrade

BaseLiner increases NXT long-term overlay stability with more than 1.5 nm

without overlay maintenance time

BaseLiner keeps NXT focus uniformity stable and well below 25 nm

without focus maintenance time

15


Improves scanner

productivity by

around 1.5%

The corrections are fed back to the

scanner via the fab automation system.

Running on a dedicated BaseLiner

server, the engine performs the whole

comparison and calculation process in

just three minutes – saving hours

of engineering time.

Flexibility in implementation

BaseLiner offers a lot of freedom for

customization in implementation and

delivery. Fingerprint measurements

can be performed at any frequency the

customer chooses, but to ensure target

performance is continuously maintained,

it is recommended that checks are carried

out every three days.

The correction calculation engine

requires a server (one per fab) supported

with a dedicated Lithography Computing

Platform which is easily scalable for

adding further computational lithography

tools or other wafer fab applications.

Delivering real results

Since its launch, BaseLiner has proven

extremely popular with ASML customers.

Almost all customers running TWINSCAN

NXT or latest generation immersion XT

systems opt for the BaseLiner scanner

stability option. And they have been

reporting back some impressive results.

Typically, BaseLiner improves scanner

productivity by around 1.5%. At the

same time, customers have seen

scanner overlay-related rework halve and

matched-machine overlay improvements

of around 40%. And this has been

achieved with a labor saving of multiple

full-time equivalents (FTEs). The end

result is that, when equipping a whole fab

with the BaseLiner-YieldStar combination,

many customers recover their investment

in just 4 months.

BaseLiner also works well on dry ArF tools.

Latest customer data has shown that

XT:1400F matched overlay towards

NXT:1950i can be kept well below 8 nm

and, with additional corrections per

exposure even below 6 nm. Not once,

but every day.

Continuous improvement

BaseLiner is part of ASML’s ongoing effort

to help customers optimize their on-product

performance and increase yields. As

such, ASML has a detailed roadmap

for expanding BaseLiner’s functionality

and extending its applicability beyond

TWINSCAN XT and NXT systems to the

emerging TWINSCAN NXE EUV platform.

At the end of 2011, ASML released a

BaseLiner functionality upgrade called

BaseLiner 1.5. This upgrade improves

matched machine overlay (MMO) right

across the fab by allowing all systems to be

matched to one “golden reference” wafer.

In essence, BaseLiner allows customers

to “copy” their existing golden reference

wafer as many times as they like without

having to invest in scanner time, typically

boosting productivity by a further 0.5%.

Again, most of the work is done in the

offline YieldStar tool.

To make these copies, BaseLiner

calculates the difference between the

golden reference wafer and a standard

BaseLiner wafer exposed on each

scanner. The BaseLiner wafer plus the set

of differences acts as a new copy of the

reference. Every scanner in the fab – from

i-line to EUV – can then be matched to this

golden reference, increasing fab efficiency

significantly. BaseLiner 1.5 makes fleet-

matching easy.

Many customers recover

their investment in just

4 months

High-volume manufacturing at small

feature lengths means optimizing on-

product performance while keeping

the economics under control through

maximum productivity and yield.

By ensuring scanners continuously

operate according to specifications,

BaseLiner reduces both production

stoppages and the amount of reworking

required, so fabs can produce more

good wafers per month.

16

TWINSCAN NXTa thoroughbred workhorseBy Robert Kazinczi, Director Product Management

17


Abstract | The TWINSCAN NXT:1950i was

first released in 2009, allowing customers

to start learning about this revolutionary

high-throughput, high-precision immersion

ArF system. It has now evolved into a

mature, high-output solution for volume

production at today’s smallest nodes.

In the coming years, the NXT will continue

evolving through platform improvements

and system enhancement packages

to support the industry’s migration to

2x nodes and beyond.

ASML’s TWINSCAN NXT:1950i immersion

ArF scanner was designed to be a

thoroughbred among lithography systems.

Its ambitious specifications aim to make

multiple patterning in the fab feasible –

both technically and economically.

Outputs above 4100

wafers per day

But in the three years since its launch,

the TWINSCAN NXT has evolved from the

“new kid on the block” into mature

solution for high-volume production.

The thoroughbred has become a

workhorse – albeit one that targets

the cutting-edge of semiconductor

manufacturing. What’s more, ASML

has a detailed roadmap in place for

continuing that evolution over the next

three years, enhancing performance

and output to support high-volume

manufacturing down to 1x nodes.

A mature performer

The first TWINSCAN NXT systems were

shipped in 2009, allowing customers to

start learning about the new platform at

an early stage. Since then, ASML has

released a number of upgrades to bring

the platform to a production-ready state.

18

As usual with ASML, the improvements

and options will be available as in-field

upgrades, allowing manufacturers to

re-use their current installed base for

future nodes, maximizing their return on

investment in the NXT and making the

transition to new nodes more affordable.

It will also provide greater flexibility in

managing the switch to extreme ultraviolet

(EUV) lithography by allowing fab refits

to be carried out in line with planned

investment cycles.

Key targets in extending the NXT for 1x

production include squeezing on-product

overlay to just 4 nm and the total focus

budget to 60 nm. The aim is to deliver

these performance improvements while

simultaneously increasing full-field

throughput to 250 wph.

At these incredibly small feature

sizes, defects become an increasingly

challenging issue. So an important part

of preparing the NXT for 1x nodes will be

maintaining or even improving defectivity

performance. Here the main focus is on

reducing so-called “big bubble” defects.

ASML is already developing platform

enhancements that should practically

eliminate big bubbles at full throughput and

significantly improve overall defect levels

beyond the 10 per wafer typical today.

These defectivity upgrades, and others

to support production at 1x nodes, will be

available to customers starting in 2013.

Supporting industry needs

In the three years since its launch, the

TWINSCAN NXT:1950i has become well

established across the industry. During

that time, the system has evolved from

an R&D tool for early learning to a mature

solution for high-volume production.

That evolution is set to continue,

enabling manufacturers to address 2x

and 1x nodes with multiple patterning

immersion ArF lithography and manage

a smooth transition to EUV. Throughout

that evolution, the TWINSCAN NXT will

combine cutting-edge imaging and overlay

with unrivalled throughput and excellent

reliability, making it both a thoroughbred

performer and real fab workhorse.

performance gains at the same or better

imaging, overlay or focus performance.

Indeed, during beta testing, systems

that had been upgraded with the PEP

NXT package performed better than

specification in all key areas including

3-day dedicated chuck overlay, MMO,

CDU, focus uniformity, 3-day focus

stability and defectivity. In particular,

the enhanced system set-up significantly

improved overlay performance towards

the edge of the wafer, enabling an

unfiltered full-wafer MMO of 5.5 nm

at 200 wph.

Increased productivity makes production

at 2x nodes using multiple patterning

strategies financially viable. Such

strategies put greater demand on the

on-product performance a litho cell

can deliver. Hence, over the course of

2012, ASML will be releasing a number

of system enhancement packages to

improve on-product overlay and imaging

Unfiltered full-wafer

MMO of 5.5 nm

at 200 wph

For overlay, options will include TOP

packages, GridAlign next-generation

alignment and an updated Overlay

Optimizer. Imaging options will include

a focus improvement package, BaseLiner

scanner stability (see page 10), CDU

Optimizer (see page 6) and a new version

of the AGILE (air gauge improved process

leveling) system. Together, these

enhancements push matched machine

overlay (MMO) to 4.5nm, on-product

overlay down to 6 nm, CDU to 1.5 nm

and total focus control to 80 nm.

Toward 1x nodes

Looking further ahead, ASML plans to

continue extending the NXT platform

to support production at 1x nodes.

Again, this evolution will be delivered

through a mix of improvements to the

baseline platform and optional system

enhancement packages.

In particular, service pack options

released in the last twelve months have

brought average availability up to 92%

for production systems. They have also

ensured systems consistently perform

according to customers’ expectations

– both under ATP conditions and on-

product. That means throughputs of

175 wafers per hour (wph) under ATP

conditions and 190 wph under full-field

conditions. ATP matched machine

overlay (MMO) is just 5.5 nm and critical

dimension uniformity is 2.5 nm, while

on-product overlay of better than 8 nm

is regularly achieved.

Those numbers have seen the NXT

become a popular choice for fabs in all

sectors of the semiconductor industry.

Some 120 systems have been shipped to

memory, logic and foundry customers, and

are performing according to specification

day in, day out. Outputs above 4100 wafers

per day have been achieved, and individual

NXT systems have already exposed more

than one million wafers.

Ongoing evolution for 2x nodes

The combination of thoroughbred

performance and workhorse production

has seen the TWINSCAN NXT become

well established for volume production

at today’s cutting-edge nodes. However

the NXT was always intended as a

multi-node system, and ASML has a

detailed roadmap to extend the system’s

performance in line with industry demand

for manufacturing at 2x nm nodes.

This roadmap includes both upgrades

to the baseline platform and optional

system enhancement packages.

A number of these planned option

packages – including productivity

upgrades, overlay improvements and

the FlexWave programmable wavefront

solution – were discussed in last

summer’s issue of Images. And the first

of them, the PEP NXT productivity

upgrade, has already started shipping.

The PEP NXT:1950i package increases

system productivity by 15-20%, making

full-field throughput of 230 wph possible.

Importantly, the upgrade enables these

19


0

2

4

6

8

1 2 3 4

YXLot (1.5,1.3)

Lot 1

wafer wafer wafer

Lot 2 Lot 3

Ove

rlay

(99.

7% ),

nm

Ove

rlay

(99.

7% ),

nm

Ove

rlay

(99.

7% ),

nm

0

2

4

6

8

1 2 3 4

YXLot (1.6,2.0)

0

2

4

6

8

1 2 3 4

YXLot (1.7,2.0)

1.5 nm

4.8 nm

2.0 nm 2.0 nm

Stable 2 nm full wafer overlay exposed at 230 wph dedicated chuck mode

Matched machine overlay improved to sub 5 nm full wafer

0

2.5

5

7.5

10

1 2 3

YXLot (4.6,4.8)

wafer

Ove

rlay

99.7

% u

nfilt

ered

[nm

]

NXT:1950i1H2012

0

1

2

3

4

5

6

NXT:1950i1H2011

Typical matching performance (machine to machine)

< Overlay Grid

NXT:1950i2H2011

7

Ove

rlay

99.7

% u

nfilt

ered

[nm

]

10 nm 99.7%x: 1.5 nmy: 1.3 nm

10 nm 99.7%x: 4.6 nmy: 4.8 nm

10 nm 99.7%x: 1.6 nmy: 2.0 nm

10 nm 99.7%x: 1.7 nmy: 2.0 nm

MMO

20

Linkou

21


That’s why we established the 200 mm

competence center in 2009. Today, the

competence center comprises some

200 engineers based at the ASML

Center of Excellence (ACE) in Linkou,

Taiwan supported by a similar number

of colleagues in Europe and the US –

all dedicated to our PAS 5500

lithography platform.

Concentrating our smaller-wafer know-

how in this way creates a critical mass of

expertise covering system development,

manufacturing and customer support.

This in turn allows us to continue

offering a complete range of life-cycle

management services for PAS 5500

systems. These include expert service

support, refurbishing and reselling used

systems and developing new products

that improve performance or tailor

systems for new applications.

Second life

The continued importance of the 200

mm and below sector drives a strong

market for pre-owned systems. ASML is

active in this market through the 200 mm

competence center. Last year, ASML gave

some 60 PAS machines a second life

– 30 through direct fab-to-fab shipping

and 30 through refurbishment.

A bright future for ASML’s refurbished toolsBy Rob van Keulen, Director Mature Products & Services, and Steven van Heek, New Business Development & Marketing

Production on 300 mm wafers may now

be the mainstream, but the 200 mm and

smaller sector is still hugely important in

the semiconductor industry. Around 50%

of wafers processed globally are 200 mm

or smaller – accounting for about 25% of

chip production. These smaller wafer sizes

are particularly attractive for special

applications and smaller-volume markets.

Indeed, the sector is predicted to continue

growing over the long term in areas such

as MEMS, analog, LEDs, hard disks and

bio-electronics.

Ongoing commitment

to service and enhance

the installed base

Going back more than 25 years, ASML’s PAS

systems have always led the way in customer

value through a combination of performance

and productivity at wafers sizes ranging from

75 to 200 mm (3”-8”). As a result, the current

PAS installed base comprises some 2000

systems worldwide. And although ASML

no longer manufactures new PAS systems,

we are still committed to ensuring the

installed base delivers maximum value.

Abstract | Based at the ASML Center of

Excellence (ACE) in Linkou, Taiwan, ASML’s

200 mm competence center is a unique

resource for customers of the PAS 5500

platform. It provides a critical mass of

expertise, ensuring valuable knowledge

of this popular platform is retained in the

semiconductor industry. It offers expert

service support, pre-owned systems

refurbished to the highest standards, and

new products that improve performance

or tailor systems for new applications.

22

Unlike a traditional equipment reseller,

ASML is able to refurbish surplus

equipment to an unmatched level before

shipping it to a new owner. In choosing an

ASML refurbished system, the customer

gets a system that performs to an agreed

specification and is delivered at an agreed

time. This allows them to plan production

with confidence, greatly reducing the

technical, timing and financial risk of

buying pre-owned equipment.

ASML offers two levels of refurbishment

services. In a factory refurbishment, the

system is transported to the ACE facility

where it is refurbished to the original ATP

specification and re-configured to meet pre-

agreed customer requirements. The system

is delivered with a full 12 month warranty, and

an extended optics warranty is available.

The second option is our Refurb

Lite service. Here, the system is

refurbished to guarantee mutually

agreed key specifications based on a

pre-refurbishment audit. The system

can also be upgraded with a range of

performance enhancement options,

and is supplied with a 6-month warranty.

New applications

The ability to configure a system during

refurbishment is a particularly attractive

feature for customers in new and niche

applications. For example, recently a

high-end watch maker was looking for

a cost-effective lithography solution for

manufacturing key watch components

(such as the balance spring) from silicon.

Making these parts from silicon rather

than metal would improve the watch’s

lifetime and accuracy. But it requires

a system that is capable of backside

alignment of the wafer. ASML is the

only optical lithography supplier to offer

this possibility – through our 3DAlign

option. As a result, the buyer selected

a refurbished PAS 5500 system.

During the refurbishment process, the

200 mm competence team fitted the

3DAlign package and tuned the system

performance to suit this rather unusual

lithography application.

The system has now been running for

almost a year, helping the manufacturer

deliver market leading timing accuracy

in its top-of-the range watches.

Last year, ASML gave

60 PAS machines

a second life

Balancing i-line supply and demand

The competence center’s ability to tailor

systems to meet unique application

demands was a vital part of another

recent refurbishment project. A hard

drive manufacturer wanted 200 mm i-line

systems to increase its thin-film head (TFH)

production, and approached ASML about

purchasing a number of refurbished PAS

5500/450F systems.

During discussions, the customer

mentioned that its existing i-line systems

were plagued by a regular build up of

material on the lens and other internal

components, affecting performance and

requiring frequent production stoppages for

cleaning. The competence center realized

this deposit was due to outgassing from the

thick resists used when manufacturing disk

heads on i-line systems. So it suggested

23


systems in the field. Through its service

solutions, it tracks wear and tear on parts.

It also actively engages with the supply

chain to monitor, identify and solve spare

parts supply issues. This information

can help customers plan maintenance

programs, and is also important input for

our refurbishment projects. Moreover, the

competence center solves around 20 End

of Life issues per quarter for customers.

Ongoing commitment

ASML’s 200 mm competence center is a

unique resource for PAS 5500 customers.

By providing a focal point for our smaller-

wafer know-how, it ensures valuable

knowledge about the platform is retained

in the industry for customers to call on.

As a result, customers can be sure of the

best cost and value of ownership whether

they are looking to purchase pre-owned

systems or extend the profitability of their

existing equipment. The center is a sign

of ASML’s ongoing commitment to

service and enhancement of the installed

base for a platform that continues

to play an important role in today’s

semiconductor industry.

a significant undertaking, the PAS 5500’s

modular architecture helps keep delivery

times down. And the conversion means

customers have access to new i-line tools

on a planned timeline.

Systems refurbished

to meet unique application

demands

Extending productive lifetimes

Besides these “second life” services,

the competence center also brings

added value for customers who

already have an installed base of PAS

5500 systems. The center offers a full

range of service solutions, allowing

manufacturers to balance costs while

gaining maximum value. It also provides

extensive application and equipment

support such as productivity and yield

enhancement projects.

In addition, the competence center

helps extend the lifetime of all PAS 5500

adding an extraction hood, which it

designed and then fitted as part of the

refurbishment process. The extraction hood

works so well, it has now been fitted to the

customer’s other i-line tools.

This project also highlighted another way the

200 mm competence center adds value to

the used equipment market: by balancing

supply and demand for different system

types. As the original manufacturer of the

PAS 5500 systems, ASML is uniquely placed

to convert systems from one lithography

wavelength to another. Here the customer

was looking for a PAS 5500/450F. Indeed,

there is strong demand in many markets

for this top-of-the-range i-line system.

But only a very limited number of units

become available on the pre-owned market.

So ASML purchased a surplus PAS

5500/500 KrF system and converted

it to a PAS5500/450 i-line system. This

involves replacing the lens, light source

and associated components, while the

rest of the system underwent a standard

refurbishment plus customized adjustments

to prevent ESD damage to the TFH wafers.

Although conversion from KrF to i-line is

www.asml.com

Corporate Headquarters

De Run 6501

5504 DR Veldhoven

The Netherlands

Phone +31 40 268 30 00

United States

8555 South River Parkway

Tempe, AZ 85284 USA

Phone +1 480 383 4422

Asia

Suite 1702-3 17th Floor

100 Queen’s Road Central

Hong Kong, SAR

Phone +852 2295 1168

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