SEMI MEMS Technical Seminar, Milan Thomas - Evolution... · Process Solutions for Next Generation...

©2014 SPTS Technologies - Confidential & Proprietary

‘Evolution or Revolution?

Process Solutions for Next Generation MEMS’

SEMI MEMS Technical Seminar, Milan Dr Dave Thomas

Marketing Director, Etch Products

23 September 2014

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This presentation and the information contained within it is the property of SPTS Technologies and is confidential. Any duplication, disclosure, distribution, dissemination or copying

of this presentation or its contents or use for any purpose other than that for which it is supplied is strictly prohibited, without the prior written consent of SPTS Technologies. © 2014 SPTS Technologies

■ Bosch Process – the ‘foundation’ of MEMS

■ What does the future hold for the Bosch process?

■ Semiconductor industry in 1994

■ DRIE product evolution

■ Bosch process technology trends

■ Today’s process capability

■ Feature types

■ Feature sizes

■ Aspect ratios

■ Bow & CD control

■ Sidewall smoothness

■ End-point detection

■ Role of the Advanced Packaging market

■ Competing technologies

■ Conclusions

Contents

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■ Awarded IEEE Jun-Ichi Nishizawa Medal in Amsterdam in 2014

■ Patented in 1994

■ Licensed to other manufacturers

■ SPTS was the first licensee & shipped the first

etch tool based on the Bosch process in 1995

■ SPTS has shipped ~1100 modules since

■ Total license payments to Bosch (all users)

estimated at Euro12M

Bosch Process – The ‘Foundation’ of MEMS

Franz Laermer (VP Corp Sector Research & Advanced Engineering, Bosch Stuttgart)

Andrea Urban (Senior Expert, Eng Sensor Process Technol Dept, Bosch Reutlingen)

The development of the deep reactive ion etching

process by Franz Laermer and Andrea Urban

revolutionized the micro-electro-mechanical

systems (MEMS) industry by enabling cost-

effective production and proliferation of devices

such as the tiny sensors found in automobile air

bag and anti-skidding systems, as well as in

today’s smartphones and laptop computers.

http://www.ieee.org/index.html?WT.mc_id=hpf_logo

http://www.google.co.uk/url?url=http://robert-bosh-odbytova.czechtrade.us/&rct=j&frm=1&q=&esrc=s&sa=U&ei=hR0YVJyOFM7y7Abb8IFo&ved=0CBwQ9QEwAg&usg=AFQjCNGhqSq3wPX-U-hzT1sIfPzoSLVJrw

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■ ~20 years on

■ Can the Bosch process continue to adapt to new

requirements?

■ What are the known limitations?

■ What are the competing technologies?

■ Which technology will win?

What Next for the Bosch Process?

Evolution or Revolution?

http://www.google.co.uk/url?url=http://greatmindsoftheworld.com/charles-darwin/&rct=j&frm=1&q=&esrc=s&sa=U&ei=BEoaVPiqGpLbauGUgOgI&ved=0CBgQ9QEwAQ&usg=AFQjCNFd8ZgK7S-asA4F1KFV8gXMvVv-CQ

http://www.google.co.uk/url?url=http://en.wikipedia.org/wiki/Viva_la_Revolution&rct=j&frm=1&q=&esrc=s&sa=U&ei=TkoaVOaoIJDbaK7pguAG&ved=0CC4Q9QEwDA&usg=AFQjCNEi2LwNU2alhkrW4qQs90dgVHtP_A

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■ Intel released its Pentium processor

■ But most people were still using 286/386

■ I joined Electrotech in 1994

■ 1 computer shared between 8 people

■ 2 e-mail accounts in the company

■ Keeping Fax machines supplied with paper!

Semiconductor Industry in 1994

1994 Today

Feature size 0.35µm ~18nm

DRAM Generation 64Mb 8Gb

Largest wafer 200mm 300/450mm

Metals W plug

Al slab

Cu

Dielectrics SiO2 Low k

Integration Subtractive etch Dual Damascene

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SPTS DRIE Product Evolution

Rapier

ICP

HDP source

High power sources

‘Single Sources’

High Power ‘Dual Source’

ProNova2

DSi

Pegasus

DSi-v

1995

3.3-5.6µm/min ~2005

26µm/min

Today

35µm/min

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1994/5

■ Taking advantage of a new

approach

■ Checking what

could/couldn’t be done

■ Focus on automotive

applications

■ Technology was key

■ Cost was second

■ Yields were

low/unimportant

Today

■ How can we make better

products?

■ Discovering new limits

■ Consumer, automotive,

biomedical ….

■ Technology still key

■ Smaller features, higher

ARs, tilt control, CD

control …

■ But Cost also key

■ Higher etch rates

■ Higher productivity

■ Higher yields

Bosch Process Technology Trends

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MEMS = Shapes in Silicon

High Aspect Ratio

1.6 x 98 µm trenches

~60:1 AR

Smooth walls

<20nm scallops

Through Wafer

Sensors

Microphones

NEMS

50nm features

High Rate

Cavities, Caps,

ink-jets High Aspect Ratio

~0.4 µm trenches

~90:1 AR

SOI

2.5 x 25µm

Low Tilt

<0.1º

Mixed isotropic/

anisotropic

processing

High Aspect Ratio

4 x 160 µm trench/TSV

40:1 AR

Complex shapes

High Aspect Ratio

8 x 180 µm trench/TSV

22:1 AR

High Aspect Ratio

1.5 x 36µm trench

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■ Unprecedented scaling capability of Bosch etching

Extendibility to nm Scale Features

1µm

spacing

150nm

50nm

10µm spacing

■ Mainstream etch equipment typically confined to 2-3 nodes

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Smaller Features, Higher ARs

Established

devices

Emerging devices

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■ 8 x 180µm (22:1 AR) trench for autofocus device

Profile & Bow Control

Profile ranges

Rapier = ~0.14°

Rapier-cd (avg) = ~0.07°

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Scallop Control = Smoother Walls

Faster gas switching Modify chemistry

2.7 x 55µm trench

<20nm Sc

10 x 70µm TSV

<30nm Sc

Base

Top

5 x 50µm TSV

~5nm ‘waves’

<20nm Sc <10nm Sc 80 x 500nm trenches

~5nm ‘waves’

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■ Large operating envelope

■ Applicable to all etches to a stop layer

■ Detection limit <0.05%

Claritas End-point Detection

Etch Chamber

Rapid fluorination

of SiF to SiF4

Unable to ‘see’

SiF*

Claritas Unit

High concentration

of SiF4 cracked to

re-form SiF*

Easily detected

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■ MEMS is predominantly a ≤200mm activity

■ SPTS has already shipped 300mm DRIE modules for

MEMS

■ Bridged 2/300mm equipment

■ Currently sized for 200mm wafers

■ 300mm process qualification has started at customer sites

■ Advanced Packaging is predominantly a 2/300mm activity

■ CIS packaging currently transitioning from 200mm to 300mm

■ Other TSV/VR etches are already at 300mm

■ Broad range of DRIE process types have already been

scaled to 300mm

■ No inherent scaling issues

■ Advanced Packaging market has mitigated any risk of

MEMS manufacturers wishing to go to 300mm

DRIE & Wafer Size

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Bosch/Related Processes for Adv Packaging

Interposer TSV Via Middle TSV

‘Conventional’ TSVs

■ Made 300mm MEMS an enticing proposition

Via Last TSV

Tapered

100 µm diam

No scallops

Via Last TSV

Vertical

50 x 120 µm

<160 nm Sc

20 x 160 µm

<160 nm Sc 10 x 100 µm

<70 nm Sc

5 x 50 µm

<6 nm Sc 50 x 100 µm

<150 nm Sc

20 x 100 µm

<150 nm Sc MEMS TSVs

(Poly or W fill)

8 x 180 µm

<200nm Sc

4 x 160 µm

<50 nm Sc

Via Reveal

Via Last ‘Spacer Etch’

Top

Mid

Base

No oxide

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■ Wet etching of Si

■ Features governed by preferential etching along crystal planes

■ Only valuable for large non-critical devices

■ Single step dry etching of Si

■ Depth limit 20-50µm

■ Limited mask selectivity of ~20:1

■ Grass in larger features

■ Cryogenic dry etching of Si

■ Interesting to academics

■ Smooth sidewalls

■ Max etch rate 2-3µm/min

■ Not manufacturable (-110°C, PR cracking etc)

■ LASER drilling of Si

■ Unsophisticated hole shapes

■ No selectivity to under-layers

■ New materials

■ Glasses, polymers ….

Competing Technologies

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■ Bosch process has continued to evolve & meet the

changing/challenging needs of the MEMS market

■ Smaller features, high aspect ratios, CD control,

profile control, end-pointing, higher etch rates ….

■ New materials are growing in importance for MEMS

■ Eg glasses, polymers

■ But Si will remain the dominant material

■ Easy to process

■ Mechanically stable

■ Ease of integration with ICs

■ TSV formation for Advanced Packaging paves the

way for 300mm MEMS

■ Significant customer interest & pull

■ Extendibility of the Bosch process has been

unprecedented in the Semi industry

■ Fundamentally unchanged in 20 years

Conclusions

Evolution wins!

http://www.google.co.uk/url?url=http://greatmindsoftheworld.com/charles-darwin/&rct=j&frm=1&q=&esrc=s&sa=U&ei=BEoaVPiqGpLbauGUgOgI&ved=0CBgQ9QEwAQ&usg=AFQjCNFd8ZgK7S-asA4F1KFV8gXMvVv-CQ

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Conclusions

Evolution wins!

■ Bosch process has continued to evolve & meet the

changing/challenging needs of the MEMS market

■ Smaller features, high aspect ratios, CD control,

profile control, end-pointing, higher etch rates ….

■ New materials are growing in importance for MEMS

■ Eg glasses, polymers

■ But Si will remain the dominant material

■ Easy to process

■ Mechanically stable

■ Ease of integration with ICs

■ TSV formation for Advanced Packaging paves the

way for 300mm MEMS

■ Significant customer interest & pull

■ Extendibility of the Bosch process has been

unprecedented in the Semi industry

■ Fundamentally unchanged in 20 years

SEMI MEMS Technical Seminar, Milan Thomas - Evolution... · Process Solutions for Next Generation...

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