7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 14

T H E I N T E R N A T I O N A L M A G A Z I N E F O R S E M I C O N D U C T O R M A N U F A C T U R I N G

JUNE 2009

wwwsolid-statecom

Measuring monolayer graphite with

reflectometry-ellipsometry p 18

ODP metrology with floating n ampk rsquos p 22

Camera-phone optics p 26

Thin films for 3D p 12

Incorporating

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 24

456nm

456nm

486nm427nm

526nm

486nm

1042nm

200nm

Thin films for 3D ALD fornon-planar topographies

DEPOSIT ION

Extreme and non-planar substrate topog-

raphies that provide challenges for conventional thin film deposition tech-

niques are abundant Such applications span the range of structures from

DRAM trench cells and MEMS devices to coatings of esoteric materials such

as aerogels viruses nanotubes microlenses piping grains and particles

and even porous dental material For these types of important and inter-

esting applications atomic layer deposition (ALD) provides an exceptional

technology for overcoming such challenges in order to achieve superior

film uniformity step coverage and film conformality

EXECUTIVE OVERVIEW

Following the seminal work o Aleskovskii [1] and Suntola[2] in establishing the field o ALD science the subject hasrapidly expanded in both academic and commercial arenas toencompass a wide variety o applications Te prolieration o

this technology has been principally due to the advantages offeredby the deposited film quality and conormality resulting rom theinherent growth mechanism ound in ALD Films are deposited bysequentially pulsing appropriate precursor material into the ALDreaction chamber ollowed by a purge cycle o an inert gas Tissequence is repeated again or each subsequent layer A key elemento the deposition is the sel-limiting nature o the process that allows

repeatable monolayer-by-monolayer growth with a airly broadprocess window Te resulting films are pinhole-ree uniorm andextremely conormal

ALD growth mechanism

Te ALD material system that exhibits these characteristics best isAl2O3 It is typically grown thermally at 80degndash250degC with trimethy-laluminium (MA) and water as the precursors Te reactions areas ollows or growth on a Si surace [3] Volatile MA reacts in asel-limiting ashion with hydroxyl groups terminating the Si suraceTis reaction deposits aluminum atoms with dangling methyl groupswhile excess MA and methane are pumped away Next water is

introduced which readily reacts with the methyl groups resultingin the ormation o Al-O bridges and the regeneration o suracehydroxyls Tis serves to ready the surace or the next cycle startingwith another MA pulse Deect-ree layers o Al2O3 are ormed ineach complete cycle with a growth rate o ~10Aringcycle achievable ina large part o the process window

Te reaction mechanism or other materials such as nitridesand sulfides is similar given the reaction o the second precursorwith the chemisorbed surace species However the ALD o

certain metals(ie platinumor rutheniumfilms) proceedsprimarilythough acombustionmechanism Insuch cases the

second reactantis usually oxygen or ozone whichhelps convert the organic ligandso the precursor into volatilecarbonates (CO and CO2) and thereduction o the precursor into ametallic state

ALD and high-aspect

ratio topography

Along with the superior flat filmuniormity that can be achieved

through ALD a striking eature othe deposition process is the abilityto conormally coat 3D geome-tries and high-aspect ratio (HAR)eatures o take ull advantageo this eature an ALD systemis required to have a true closed-

vacuum reaction chamber Tisprovides the user with the neededflexibility to moderate the exposuretime o the samples to the reactantsIn this manner small precursor

pulses can be held in the reactionchamber or longer periods to increasethe exposure o the sample to thegrowth chemistries Tis is the keyto depositing conormal coatings onstructures with extreme geometriesand aspect ratios

An elegant and simple mathe-matical model that explains the condi-tions required to coat HAR holes trenches and arbitrary shapeshas been described in detail by Gordon et al [4 5] Te results othe model show that or a hole o length l diameter d and aspect

Ganesh M Sundaram Eric W Deguns Ritwik Bhatia Mark J Dalberth Mark JSowa Jill S Becker Cambridge NanoTech Inc 68 Rogers St Cambridge MA USA

COVER ARTICLE

Figure 1 Cross-sections of holes 7microm

deep and 100nm in diameter On the

left is a complete uncoated hole On the

right are higher magnification images

of the top middle and bottom of a

hole coated conformally with a uniform

silica film 46nm thick made by four

ALD cycle s

Reprinted with revisions to format from the June 2009 edition of SOLID STATE TECHNOLOGY

Copyright 2009 by PennWell Corporation

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 34

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 44

a) b) e)

f)

d)

c)

50nm Pore

Protein

10nm 10nm

TiO2

Thin films for 3D

tures with minimal reliance on standard lithographic patterning

Macro size features

Te issues o extreme topography are not limited to nanosize devicesOfen conceptually simple requirements or large objects such ascoating the interior o a long pipe with a convoluted interior can

generate the same challenges mdash namely the ability to achieve auniorm coating when large aspect ratios are involved Again thiscan be handled using ALD in exposure mode Other examples omacro-sized eatures include arrays o micro drill bits that requirecoatings o thin film with anti-wear material Te geometry o thebits consists o complex curves and shadowed suraces which wouldbe difficult to coat by conventional techniques but can be coated ina batch process by ALD

Particles and powders

Particles and powders represent a class o non-planar sampleswhere the potential or useul applications is large provided they

are able to be coated For example alumina coatings o boronnitride (BN) particles help to reduce their thermal conductivityand improve their surace wetting characteristics making thecoated particles an excellent fil ler material or microelectronicpackaging Applications similar to this also exist in the biologicaland consumer fields

Te main problem with coating particles stems rom their irregularshapes which include undercut profiles additionally the act o coatingthem could lead to aggregation (clumping together) o the particlesTere are ALD methods many o them developed by the George Groupat the University o Colorado at Boulder to overcome these issues[11] Te main eature o these designs is to maintain sufficient flow

movement around the particles during the ALD growth process suchthat the particles can remain separated rom one another Te ALDgrowth in turn allows the irregular sizes and shapes o the particlesto be coated uniormly over the entire surace

Conclusion

While planar suraces continue to require thin film coatings 3Ddevices and objects with stringent coating requirements continue toemerge Tese application spaces are greatly aided by the use o ALDtechnology which serves to ulfill the requirements and illuminatethe path in the exploration or ever-increasing thin films coating orextreme geometries

References1 AM Shevjakov GN Kuznetsova and VB Aleskovskii in Chemistry of

High Temperature Materials Proceedings o the Second USSR Conerenceon High-emperature Chemistry o Oxides Leningrad USSR 26-29 1965(Nauka Leningrad 1967) pp 149-155 in Russian

2 Suntola and J Antson US Patent No 4058430 (15 Novenber 1977)3 RL Puurunen J Appl Phys 97 121301 (2005) also wwwcambridgenan-

otechcom

4 Roy G Gordon Dennis Hausmann Esther Kim and Joseph ShepardChemVap Deposition 9 (2) 73 (2003)5 SO Kucheyev J Biener F Baumann YM Wang AV Hamza Z Li DK

Lee and RG Gordon Langmuir 24 943 (2008)6 C Detavernier J Dendooven D Deduytsche and J Musschoot ECS Trans-

actions 16 (4) 239 (2008)7 D Hausmann J Becker S Wang and RG Gordon Science 298 402

(2002)8 JS Becker PhD Tesis (2003)9 S S Kistler J Phys Chem 34 52 193210 M Knez K Nielsch AJ Patil S Mann and U Goumlsele ECS Transactions

3 (15) 219 (2007)11 H J Fan M Knez R Scholz D Hesse K Nielsch M Zacharias and U

Goumlsele Nano Letters 7 (4) 993 (2007)

G983137983150983141983155983144 M S983157983150983140983137983154983137983149 received his PhD in physics at OxordU and is VP o echnology at Cambridge NanoTech Inc 68

Rogers Street Cambridge MA 02142 USA ph 617-674-8800Sundaramcambridgenanotechcom

E983154983145983139 W D983141983143983157983150983155 received his PhD in chemistry at the U oCaliornia ndash Santa Barbara and is an ALD application scientist atCambridge NanoTech Inc

R983145983156983159983145983147 B983144983137983156983145983137 received his PhD in chemical engineering romPurdue U and is a senior research scientist at Cambridge Nano-

Tech Inc

M983137983154983147 J D983137983148983138983141983154983156983144 received his PhD in physics at the U o Colo-rado Boulder and is a physicistprincipal engineer at Cambridge

NanoTech Inc

M983137983154983147 J S983151983159983137 received his PhD in chemical engineering romPrinceton U and is a senior research scientist at Cambridge Nano-

Tech Inc

J983145983148983148 S B983141983139983147983141983154 received her PhD in chemistry at Harvard UShe ounded Cambridge NanoTech in 2003

Figure 4 Micrograph of tobacco mosaic virus ALD-based TiO2 was deposited to create a tem-

plate for 3D nanostructures

As the leading provider of Atomic Layer Deposition (ALD) solu-

tions Cambridge NanoTech has over 150 ALD systems installed

worldwide Cambridge NanoTech applies its expertise to solve

unique coating challenges by collaborating on breakthrough

research with customers and by offering next-generation thermal

plasma-enhanced and large-area ALD systems To learn more visit

us at wwwcambridgenanotechcom

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 24

456nm

456nm

486nm427nm

526nm

486nm

1042nm

200nm

Thin films for 3D ALD fornon-planar topographies

DEPOSIT ION

Extreme and non-planar substrate topog-

raphies that provide challenges for conventional thin film deposition tech-

niques are abundant Such applications span the range of structures from

DRAM trench cells and MEMS devices to coatings of esoteric materials such

as aerogels viruses nanotubes microlenses piping grains and particles

and even porous dental material For these types of important and inter-

esting applications atomic layer deposition (ALD) provides an exceptional

technology for overcoming such challenges in order to achieve superior

film uniformity step coverage and film conformality

EXECUTIVE OVERVIEW

Following the seminal work o Aleskovskii [1] and Suntola[2] in establishing the field o ALD science the subject hasrapidly expanded in both academic and commercial arenas toencompass a wide variety o applications Te prolieration o

this technology has been principally due to the advantages offeredby the deposited film quality and conormality resulting rom theinherent growth mechanism ound in ALD Films are deposited bysequentially pulsing appropriate precursor material into the ALDreaction chamber ollowed by a purge cycle o an inert gas Tissequence is repeated again or each subsequent layer A key elemento the deposition is the sel-limiting nature o the process that allows

repeatable monolayer-by-monolayer growth with a airly broadprocess window Te resulting films are pinhole-ree uniorm andextremely conormal

ALD growth mechanism

Te ALD material system that exhibits these characteristics best isAl2O3 It is typically grown thermally at 80degndash250degC with trimethy-laluminium (MA) and water as the precursors Te reactions areas ollows or growth on a Si surace [3] Volatile MA reacts in asel-limiting ashion with hydroxyl groups terminating the Si suraceTis reaction deposits aluminum atoms with dangling methyl groupswhile excess MA and methane are pumped away Next water is

introduced which readily reacts with the methyl groups resultingin the ormation o Al-O bridges and the regeneration o suracehydroxyls Tis serves to ready the surace or the next cycle startingwith another MA pulse Deect-ree layers o Al2O3 are ormed ineach complete cycle with a growth rate o ~10Aringcycle achievable ina large part o the process window

Te reaction mechanism or other materials such as nitridesand sulfides is similar given the reaction o the second precursorwith the chemisorbed surace species However the ALD o

certain metals(ie platinumor rutheniumfilms) proceedsprimarilythough acombustionmechanism Insuch cases the

second reactantis usually oxygen or ozone whichhelps convert the organic ligandso the precursor into volatilecarbonates (CO and CO2) and thereduction o the precursor into ametallic state

ALD and high-aspect

ratio topography

Along with the superior flat filmuniormity that can be achieved

through ALD a striking eature othe deposition process is the abilityto conormally coat 3D geome-tries and high-aspect ratio (HAR)eatures o take ull advantageo this eature an ALD systemis required to have a true closed-

vacuum reaction chamber Tisprovides the user with the neededflexibility to moderate the exposuretime o the samples to the reactantsIn this manner small precursor

pulses can be held in the reactionchamber or longer periods to increasethe exposure o the sample to thegrowth chemistries Tis is the keyto depositing conormal coatings onstructures with extreme geometriesand aspect ratios

An elegant and simple mathe-matical model that explains the condi-tions required to coat HAR holes trenches and arbitrary shapeshas been described in detail by Gordon et al [4 5] Te results othe model show that or a hole o length l diameter d and aspect

Ganesh M Sundaram Eric W Deguns Ritwik Bhatia Mark J Dalberth Mark JSowa Jill S Becker Cambridge NanoTech Inc 68 Rogers St Cambridge MA USA

COVER ARTICLE

Figure 1 Cross-sections of holes 7microm

deep and 100nm in diameter On the

left is a complete uncoated hole On the

right are higher magnification images

of the top middle and bottom of a

hole coated conformally with a uniform

silica film 46nm thick made by four

ALD cycle s

Reprinted with revisions to format from the June 2009 edition of SOLID STATE TECHNOLOGY

Copyright 2009 by PennWell Corporation

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 34

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 44

a) b) e)

f)

d)

c)

50nm Pore

Protein

10nm 10nm

TiO2

Thin films for 3D

tures with minimal reliance on standard lithographic patterning

Macro size features

Te issues o extreme topography are not limited to nanosize devicesOfen conceptually simple requirements or large objects such ascoating the interior o a long pipe with a convoluted interior can

generate the same challenges mdash namely the ability to achieve auniorm coating when large aspect ratios are involved Again thiscan be handled using ALD in exposure mode Other examples omacro-sized eatures include arrays o micro drill bits that requirecoatings o thin film with anti-wear material Te geometry o thebits consists o complex curves and shadowed suraces which wouldbe difficult to coat by conventional techniques but can be coated ina batch process by ALD

Particles and powders

Particles and powders represent a class o non-planar sampleswhere the potential or useul applications is large provided they

are able to be coated For example alumina coatings o boronnitride (BN) particles help to reduce their thermal conductivityand improve their surace wetting characteristics making thecoated particles an excellent fil ler material or microelectronicpackaging Applications similar to this also exist in the biologicaland consumer fields

Te main problem with coating particles stems rom their irregularshapes which include undercut profiles additionally the act o coatingthem could lead to aggregation (clumping together) o the particlesTere are ALD methods many o them developed by the George Groupat the University o Colorado at Boulder to overcome these issues[11] Te main eature o these designs is to maintain sufficient flow

movement around the particles during the ALD growth process suchthat the particles can remain separated rom one another Te ALDgrowth in turn allows the irregular sizes and shapes o the particlesto be coated uniormly over the entire surace

Conclusion

While planar suraces continue to require thin film coatings 3Ddevices and objects with stringent coating requirements continue toemerge Tese application spaces are greatly aided by the use o ALDtechnology which serves to ulfill the requirements and illuminatethe path in the exploration or ever-increasing thin films coating orextreme geometries

References1 AM Shevjakov GN Kuznetsova and VB Aleskovskii in Chemistry of

High Temperature Materials Proceedings o the Second USSR Conerenceon High-emperature Chemistry o Oxides Leningrad USSR 26-29 1965(Nauka Leningrad 1967) pp 149-155 in Russian

2 Suntola and J Antson US Patent No 4058430 (15 Novenber 1977)3 RL Puurunen J Appl Phys 97 121301 (2005) also wwwcambridgenan-

otechcom

4 Roy G Gordon Dennis Hausmann Esther Kim and Joseph ShepardChemVap Deposition 9 (2) 73 (2003)5 SO Kucheyev J Biener F Baumann YM Wang AV Hamza Z Li DK

Lee and RG Gordon Langmuir 24 943 (2008)6 C Detavernier J Dendooven D Deduytsche and J Musschoot ECS Trans-

actions 16 (4) 239 (2008)7 D Hausmann J Becker S Wang and RG Gordon Science 298 402

(2002)8 JS Becker PhD Tesis (2003)9 S S Kistler J Phys Chem 34 52 193210 M Knez K Nielsch AJ Patil S Mann and U Goumlsele ECS Transactions

3 (15) 219 (2007)11 H J Fan M Knez R Scholz D Hesse K Nielsch M Zacharias and U

Goumlsele Nano Letters 7 (4) 993 (2007)

G983137983150983141983155983144 M S983157983150983140983137983154983137983149 received his PhD in physics at OxordU and is VP o echnology at Cambridge NanoTech Inc 68

Rogers Street Cambridge MA 02142 USA ph 617-674-8800Sundaramcambridgenanotechcom

E983154983145983139 W D983141983143983157983150983155 received his PhD in chemistry at the U oCaliornia ndash Santa Barbara and is an ALD application scientist atCambridge NanoTech Inc

R983145983156983159983145983147 B983144983137983156983145983137 received his PhD in chemical engineering romPurdue U and is a senior research scientist at Cambridge Nano-

Tech Inc

M983137983154983147 J D983137983148983138983141983154983156983144 received his PhD in physics at the U o Colo-rado Boulder and is a physicistprincipal engineer at Cambridge

NanoTech Inc

M983137983154983147 J S983151983159983137 received his PhD in chemical engineering romPrinceton U and is a senior research scientist at Cambridge Nano-

Tech Inc

J983145983148983148 S B983141983139983147983141983154 received her PhD in chemistry at Harvard UShe ounded Cambridge NanoTech in 2003

Figure 4 Micrograph of tobacco mosaic virus ALD-based TiO2 was deposited to create a tem-

plate for 3D nanostructures

As the leading provider of Atomic Layer Deposition (ALD) solu-

tions Cambridge NanoTech has over 150 ALD systems installed

worldwide Cambridge NanoTech applies its expertise to solve

unique coating challenges by collaborating on breakthrough

research with customers and by offering next-generation thermal

plasma-enhanced and large-area ALD systems To learn more visit

us at wwwcambridgenanotechcom

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 34

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 44

a) b) e)

f)

d)

c)

50nm Pore

Protein

10nm 10nm

TiO2

Thin films for 3D

tures with minimal reliance on standard lithographic patterning

Macro size features

Te issues o extreme topography are not limited to nanosize devicesOfen conceptually simple requirements or large objects such ascoating the interior o a long pipe with a convoluted interior can

generate the same challenges mdash namely the ability to achieve auniorm coating when large aspect ratios are involved Again thiscan be handled using ALD in exposure mode Other examples omacro-sized eatures include arrays o micro drill bits that requirecoatings o thin film with anti-wear material Te geometry o thebits consists o complex curves and shadowed suraces which wouldbe difficult to coat by conventional techniques but can be coated ina batch process by ALD

Particles and powders

Particles and powders represent a class o non-planar sampleswhere the potential or useul applications is large provided they

are able to be coated For example alumina coatings o boronnitride (BN) particles help to reduce their thermal conductivityand improve their surace wetting characteristics making thecoated particles an excellent fil ler material or microelectronicpackaging Applications similar to this also exist in the biologicaland consumer fields

Te main problem with coating particles stems rom their irregularshapes which include undercut profiles additionally the act o coatingthem could lead to aggregation (clumping together) o the particlesTere are ALD methods many o them developed by the George Groupat the University o Colorado at Boulder to overcome these issues[11] Te main eature o these designs is to maintain sufficient flow

movement around the particles during the ALD growth process suchthat the particles can remain separated rom one another Te ALDgrowth in turn allows the irregular sizes and shapes o the particlesto be coated uniormly over the entire surace

Conclusion

While planar suraces continue to require thin film coatings 3Ddevices and objects with stringent coating requirements continue toemerge Tese application spaces are greatly aided by the use o ALDtechnology which serves to ulfill the requirements and illuminatethe path in the exploration or ever-increasing thin films coating orextreme geometries

References1 AM Shevjakov GN Kuznetsova and VB Aleskovskii in Chemistry of

High Temperature Materials Proceedings o the Second USSR Conerenceon High-emperature Chemistry o Oxides Leningrad USSR 26-29 1965(Nauka Leningrad 1967) pp 149-155 in Russian

2 Suntola and J Antson US Patent No 4058430 (15 Novenber 1977)3 RL Puurunen J Appl Phys 97 121301 (2005) also wwwcambridgenan-

otechcom

4 Roy G Gordon Dennis Hausmann Esther Kim and Joseph ShepardChemVap Deposition 9 (2) 73 (2003)5 SO Kucheyev J Biener F Baumann YM Wang AV Hamza Z Li DK

Lee and RG Gordon Langmuir 24 943 (2008)6 C Detavernier J Dendooven D Deduytsche and J Musschoot ECS Trans-

actions 16 (4) 239 (2008)7 D Hausmann J Becker S Wang and RG Gordon Science 298 402

(2002)8 JS Becker PhD Tesis (2003)9 S S Kistler J Phys Chem 34 52 193210 M Knez K Nielsch AJ Patil S Mann and U Goumlsele ECS Transactions

3 (15) 219 (2007)11 H J Fan M Knez R Scholz D Hesse K Nielsch M Zacharias and U

Goumlsele Nano Letters 7 (4) 993 (2007)

G983137983150983141983155983144 M S983157983150983140983137983154983137983149 received his PhD in physics at OxordU and is VP o echnology at Cambridge NanoTech Inc 68

Rogers Street Cambridge MA 02142 USA ph 617-674-8800Sundaramcambridgenanotechcom

E983154983145983139 W D983141983143983157983150983155 received his PhD in chemistry at the U oCaliornia ndash Santa Barbara and is an ALD application scientist atCambridge NanoTech Inc

R983145983156983159983145983147 B983144983137983156983145983137 received his PhD in chemical engineering romPurdue U and is a senior research scientist at Cambridge Nano-

Tech Inc

M983137983154983147 J D983137983148983138983141983154983156983144 received his PhD in physics at the U o Colo-rado Boulder and is a physicistprincipal engineer at Cambridge

NanoTech Inc

M983137983154983147 J S983151983159983137 received his PhD in chemical engineering romPrinceton U and is a senior research scientist at Cambridge Nano-

Tech Inc

J983145983148983148 S B983141983139983147983141983154 received her PhD in chemistry at Harvard UShe ounded Cambridge NanoTech in 2003

Figure 4 Micrograph of tobacco mosaic virus ALD-based TiO2 was deposited to create a tem-

plate for 3D nanostructures

As the leading provider of Atomic Layer Deposition (ALD) solu-

tions Cambridge NanoTech has over 150 ALD systems installed

worldwide Cambridge NanoTech applies its expertise to solve

unique coating challenges by collaborating on breakthrough

research with customers and by offering next-generation thermal

plasma-enhanced and large-area ALD systems To learn more visit

us at wwwcambridgenanotechcom

7252019 Atomic Layer Deposition Thin Films for 3D_CNT_SST

httpslidepdfcomreaderfullatomic-layer-deposition-thin-films-for-3dcntsst 44

a) b) e)

f)

d)

c)

50nm Pore

Protein

10nm 10nm

TiO2

Thin films for 3D

tures with minimal reliance on standard lithographic patterning

Macro size features

Te issues o extreme topography are not limited to nanosize devicesOfen conceptually simple requirements or large objects such ascoating the interior o a long pipe with a convoluted interior can

generate the same challenges mdash namely the ability to achieve auniorm coating when large aspect ratios are involved Again thiscan be handled using ALD in exposure mode Other examples omacro-sized eatures include arrays o micro drill bits that requirecoatings o thin film with anti-wear material Te geometry o thebits consists o complex curves and shadowed suraces which wouldbe difficult to coat by conventional techniques but can be coated ina batch process by ALD

Particles and powders

Particles and powders represent a class o non-planar sampleswhere the potential or useul applications is large provided they

are able to be coated For example alumina coatings o boronnitride (BN) particles help to reduce their thermal conductivityand improve their surace wetting characteristics making thecoated particles an excellent fil ler material or microelectronicpackaging Applications similar to this also exist in the biologicaland consumer fields

Te main problem with coating particles stems rom their irregularshapes which include undercut profiles additionally the act o coatingthem could lead to aggregation (clumping together) o the particlesTere are ALD methods many o them developed by the George Groupat the University o Colorado at Boulder to overcome these issues[11] Te main eature o these designs is to maintain sufficient flow

movement around the particles during the ALD growth process suchthat the particles can remain separated rom one another Te ALDgrowth in turn allows the irregular sizes and shapes o the particlesto be coated uniormly over the entire surace

Conclusion

While planar suraces continue to require thin film coatings 3Ddevices and objects with stringent coating requirements continue toemerge Tese application spaces are greatly aided by the use o ALDtechnology which serves to ulfill the requirements and illuminatethe path in the exploration or ever-increasing thin films coating orextreme geometries

References1 AM Shevjakov GN Kuznetsova and VB Aleskovskii in Chemistry of

High Temperature Materials Proceedings o the Second USSR Conerenceon High-emperature Chemistry o Oxides Leningrad USSR 26-29 1965(Nauka Leningrad 1967) pp 149-155 in Russian

2 Suntola and J Antson US Patent No 4058430 (15 Novenber 1977)3 RL Puurunen J Appl Phys 97 121301 (2005) also wwwcambridgenan-

otechcom

4 Roy G Gordon Dennis Hausmann Esther Kim and Joseph ShepardChemVap Deposition 9 (2) 73 (2003)5 SO Kucheyev J Biener F Baumann YM Wang AV Hamza Z Li DK

Lee and RG Gordon Langmuir 24 943 (2008)6 C Detavernier J Dendooven D Deduytsche and J Musschoot ECS Trans-

actions 16 (4) 239 (2008)7 D Hausmann J Becker S Wang and RG Gordon Science 298 402

(2002)8 JS Becker PhD Tesis (2003)9 S S Kistler J Phys Chem 34 52 193210 M Knez K Nielsch AJ Patil S Mann and U Goumlsele ECS Transactions

3 (15) 219 (2007)11 H J Fan M Knez R Scholz D Hesse K Nielsch M Zacharias and U

Goumlsele Nano Letters 7 (4) 993 (2007)

G983137983150983141983155983144 M S983157983150983140983137983154983137983149 received his PhD in physics at OxordU and is VP o echnology at Cambridge NanoTech Inc 68

Rogers Street Cambridge MA 02142 USA ph 617-674-8800Sundaramcambridgenanotechcom

E983154983145983139 W D983141983143983157983150983155 received his PhD in chemistry at the U oCaliornia ndash Santa Barbara and is an ALD application scientist atCambridge NanoTech Inc

R983145983156983159983145983147 B983144983137983156983145983137 received his PhD in chemical engineering romPurdue U and is a senior research scientist at Cambridge Nano-

Tech Inc

M983137983154983147 J D983137983148983138983141983154983156983144 received his PhD in physics at the U o Colo-rado Boulder and is a physicistprincipal engineer at Cambridge

NanoTech Inc

M983137983154983147 J S983151983159983137 received his PhD in chemical engineering romPrinceton U and is a senior research scientist at Cambridge Nano-

Tech Inc

J983145983148983148 S B983141983139983147983141983154 received her PhD in chemistry at Harvard UShe ounded Cambridge NanoTech in 2003

Figure 4 Micrograph of tobacco mosaic virus ALD-based TiO2 was deposited to create a tem-

plate for 3D nanostructures

As the leading provider of Atomic Layer Deposition (ALD) solu-

tions Cambridge NanoTech has over 150 ALD systems installed

worldwide Cambridge NanoTech applies its expertise to solve

unique coating challenges by collaborating on breakthrough

research with customers and by offering next-generation thermal

plasma-enhanced and large-area ALD systems To learn more visit

us at wwwcambridgenanotechcom