Atomic Layer Depositionnnnwerantyjsty.ppt

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1. 1
Atomic Layer Deposition
(ALD)

2. Presentation OverviewPresentation Overview
•Definition of ALDDefinition of ALD
•Brief history of ALDBrief history of ALD
•ALD process and equipmentsALD process and equipments
•ALD applicationsALD applications
•SummarySummary

3. Definition of ALDDefinition of ALD
•ALD is a method of applying thin ALD is a method of applying thin
films to various substrates with films to various substrates with
atomic scale precision.atomic scale precision.
•Similar in chemistry to chemical vapor deposition (CVD), Similar in chemistry to chemical vapor deposition (CVD),
except that the ALD reaction breaks the CVD reaction into except that the ALD reaction breaks the CVD reaction into
two half-reactions, keeping the precursor materials separate two half-reactions, keeping the precursor materials separate
during the reaction.during the reaction.
•ALD film growth is self-limited and based on surface ALD film growth is self-limited and based on surface
reactions, which makes achieving atomic scale deposition reactions, which makes achieving atomic scale deposition
control possible.control possible.
•By keeping the precursors separate throughout the coating By keeping the precursors separate throughout the coating
process, atomic layer thickness control of film grown can be process, atomic layer thickness control of film grown can be
obtained as fine as atomic/molecular scale per monolayer.obtained as fine as atomic/molecular scale per monolayer.
Ref:Ref: "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. < "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. <http://en.wikipedia.org/wiki
/Atomic_Layer_Deposition>.>.

4. Definition of ALDDefinition of ALD
•ALD is a method of applying thin films to various substrates ALD is a method of applying thin films to various substrates
with atomic scale precision.with atomic scale precision.
•Similar in chemistry to CVD, except Similar in chemistry to CVD, except
that the ALD reaction breaks the CVD that the ALD reaction breaks the CVD
reaction into two half-reactions, reaction into two half-reactions,
keeping the precursor materials keeping the precursor materials
separate during the reaction.separate during the reaction.
•ALD film growth is self-limited and based on surface ALD film growth is self-limited and based on surface
reactions, which makes achieving atomic scale deposition reactions, which makes achieving atomic scale deposition
control possible.control possible.
•By keeping the precursors separate throughout the coating By keeping the precursors separate throughout the coating
process, atomic layer thickness control of film grown can be process, atomic layer thickness control of film grown can be
obtained as fine as atomic/molecular scale per monolayer.obtained as fine as atomic/molecular scale per monolayer.
Ref:Ref: "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. < "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. <http://en.wikipedia.org/wiki
/Atomic_Layer_Deposition>.>.

5. •ALD is a method of applying thin films to various substrates ALD is a method of applying thin films to various substrates
with atomic scale precision.with atomic scale precision.
•Similar in chemistry to chemical vapor deposition (CVD), Similar in chemistry to chemical vapor deposition (CVD),
except that the ALD reaction breaks the CVD reaction into except that the ALD reaction breaks the CVD reaction into
two half-reactions, keeping the precursor materials separate two half-reactions, keeping the precursor materials separate
during the reaction.during the reaction.
•ALD film growth is ALD film growth is self-limited and
based on surface reactions, which which
makes achieving atomic scale makes achieving atomic scale
deposition control possible.deposition control possible.
•By keeping the precursors separate throughout the coating By keeping the precursors separate throughout the coating
process, atomic layer thickness control of film grown can be process, atomic layer thickness control of film grown can be
obtained as fine as atomic/molecular scale per monolayer.obtained as fine as atomic/molecular scale per monolayer.
Definition of ALDDefinition of ALD
Ref:Ref: "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. < "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. <http://en.wikipedia.org/wiki
/Atomic_Layer_Deposition>.>.

6. Definition of ALDDefinition of ALD
•ALD is a method of applying thin films to various substrates ALD is a method of applying thin films to various substrates
with atomic scale precision.with atomic scale precision.
•Similar in chemistry to chemical vapor deposition (CVD), Similar in chemistry to chemical vapor deposition (CVD),
except that the ALD reaction breaks the CVD reaction into except that the ALD reaction breaks the CVD reaction into
two half-reactions, keeping the precursor materials separate two half-reactions, keeping the precursor materials separate
during the reaction.during the reaction.
•ALD film growth is self-limited and based on surface ALD film growth is self-limited and based on surface
reactions, which makes achieving atomic scale deposition reactions, which makes achieving atomic scale deposition
control possible.control possible.
•By keeping the precursors separate By keeping the precursors separate
throughout the coating process, atomic throughout the coating process, atomic
layer thickness control of film grown layer thickness control of film grown
can be obtained as fine as can be obtained as fine as
atomic/molecular scale per monolayer.atomic/molecular scale per monolayer.
Ref:Ref: "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. < "Atomic Layer Deposition," Wikipedia: The Free Encyclopedia, Wikimedia Foundation, 24 April 06. <http://en.wikipedia.org/wiki
/Atomic_Layer_Deposition>.>.

7. Brief History of ALDBrief History of ALD
•Introduced in 1974 by Dr. Tuomo Introduced in 1974 by Dr. Tuomo
Suntola and co-workers in Finland to Suntola and co-workers in Finland to
improve the quality of ZnS films used improve the quality of ZnS films used
in electroluminescent displays.in electroluminescent displays.
•Recently, it turned out that ALD also produces outstanding Recently, it turned out that ALD also produces outstanding
dielectric layers and attracts semiconductor industries for dielectric layers and attracts semiconductor industries for
making High-K dielectric materials.making High-K dielectric materials.
Ref:Ref: "History of Atomic Layer Deposition (ALD)," Finnish MicroNanoTechnology Network (FMNT), 24 April 2006. < "History of Atomic Layer Deposition (ALD)," Finnish MicroNanoTechnology Network (FMNT), 24 April 2006. <http://www.fmnt.fi
/index.pl?id=2913&isa=Category&op=show>.>.

8. Brief History of ALDBrief History of ALD
•Introduced in 1974 by Dr. Tuomo Suntola and co-workers in Introduced in 1974 by Dr. Tuomo Suntola and co-workers in
Finland to improve the quality of ZnS films used in Finland to improve the quality of ZnS films used in
electroluminescent displays.electroluminescent displays.
•Recently, it turned out that ALD Recently, it turned out that ALD
method also produces outstanding method also produces outstanding
dielectric layers and attracted dielectric layers and attracted
semiconductor industries for making semiconductor industries for making
High-K dielectric materials.High-K dielectric materials.
Ref:Ref: "History of Atomic Layer Deposition (ALD)," Finnish MicroNanoTechnology Network (FMNT), 24 April 2006. < "History of Atomic Layer Deposition (ALD)," Finnish MicroNanoTechnology Network (FMNT), 24 April 2006. <http://www.fmnt.fi
/index.pl?id=2913&isa=Category&op=show>.>.

9. ALD Process and ALD Process and
EquipmentsEquipments
•Releases sequential precursor gas Releases sequential precursor gas
pulses to deposit a film one layer at a pulses to deposit a film one layer at a
time on the substrate.time on the substrate.
•The precursor gas is introduced into the process chamber and The precursor gas is introduced into the process chamber and
produces a monolayer of gas on the wafer surface. A second produces a monolayer of gas on the wafer surface. A second
precursor of gas is then introduced into the chamber reacting with the precursor of gas is then introduced into the chamber reacting with the
first precursor to produce a monolayer of film on the wafer surface.first precursor to produce a monolayer of film on the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition deposition
•Since each pair of gas pulses (one cycle) produces exactly one Since each pair of gas pulses (one cycle) produces exactly one
monolayer of film, the thickness of the resulting film may be precisely monolayer of film, the thickness of the resulting film may be precisely
controlled by the number of deposition cycles.controlled by the number of deposition cycles.
Ref:Ref: A. Knop–Gericke, "Preparation of Model Systems by Physical Methods," a lecture given at Modern Methods in Heterogeneous A. Knop–Gericke, "Preparation of Model Systems by Physical Methods," a lecture given at Modern Methods in Heterogeneous
Catalysis Research Lecture Series, Fritz Haber Institute of the Max Planck Society. 24 April 06. Catalysis Research Lecture Series, Fritz Haber Institute of the Max Planck Society. 24 April 06.
<<http://w3.rz-berlin.mpg.de/%7Ejentoft/lehre/catalysis0405.html>.>.

10. •Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the A first precursor gas is introduced into the
process chamber and produces a monolayer of process chamber and produces a monolayer of
gas on the wafer surface. Then a second gas on the wafer surface. Then a second
precursor of gas is introduced into the chamber precursor of gas is introduced into the chamber
reacting with the first precursor to produce a reacting with the first precursor to produce a
monolayer of film on the wafer surface.monolayer of film on the wafer surface.
Two fundamental mechanisms:
Chemisorption saturation process
Sequential surface chemical reaction process
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition deposition
•Since each pair of gas pulses (one cycle) produces exactly one monolayer of film, Since each pair of gas pulses (one cycle) produces exactly one monolayer of film,
the thickness of the resulting film may be precisely controlled by the number of the thickness of the resulting film may be precisely controlled by the number of
deposition cycles.deposition cycles.
ALD Process and ALD Process and
EquipmentsEquipments
Ref:Ref: A. Knop–Gericke, "Preparation of Model Systems by Physical Methods," a lecture given at Modern Methods in Heterogeneous A. Knop–Gericke, "Preparation of Model Systems by Physical Methods," a lecture given at Modern Methods in Heterogeneous
Catalysis Research Lecture Series, Fritz Haber Institute of the Max Planck Society. 24 April 06. Catalysis Research Lecture Series, Fritz Haber Institute of the Max Planck Society. 24 April 06.
<<http://w3.rz-berlin.mpg.de/%7Ejentoft/lehre/catalysis0405.html>.>.

11. ALD Process and ALD Process and
EquipmentsEquipments
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition (Step 1a) deposition (Step 1a)
•Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a A first precursor gas is introduced into the process chamber and produces a
monolayer of gas on the wafer surface. Then a second precursor of gas is introduced monolayer of gas on the wafer surface. Then a second precursor of gas is introduced
into the chamber reacting with the first precursor to produce a monolayer of film on into the chamber reacting with the first precursor to produce a monolayer of film on
the wafer surface.the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech Inc., "Atomic Layer Deposition," Cambridge NanoTech Inc.,
24 April 06. <24 April 06. <http://www.cambridgenanotech.com/>.>.

12. •Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a A first precursor gas is introduced into the process chamber and produces a
monolayer of gas on the wafer surface. Then a second precursor of gas is introduced monolayer of gas on the wafer surface. Then a second precursor of gas is introduced
into the chamber reacting with the first precursor to produce a monolayer of film on into the chamber reacting with the first precursor to produce a monolayer of film on
the wafer surface.the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
ALD Process and ALD Process and
EquipmentsEquipments
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition (Step 1b) deposition (Step 1b)
Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech "Atomic Layer Deposition," Cambridge NanoTech
Inc., 24 April 06. <Inc., 24 April 06. <http://www.cambridgenanotech.com/
>.>.

13. ALD Process and ALD Process and
EquipmentsEquipments
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition (Step 1c) deposition (Step 1c)
•Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a A first precursor gas is introduced into the process chamber and produces a
monolayer of gas on the wafer surface. Then a second precursor of gas is introduced monolayer of gas on the wafer surface. Then a second precursor of gas is introduced
into the chamber reacting with the first precursor to produce a monolayer of film on into the chamber reacting with the first precursor to produce a monolayer of film on
the wafer surface.the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech "Atomic Layer Deposition," Cambridge NanoTech
Inc., 24 April 06. <Inc., 24 April 06. <http://www.cambridgenanotech.com/
>.>.

14. ALD Process and ALD Process and
EquipmentsEquipments
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition (Step 2a) deposition (Step 2a)
•Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a A first precursor gas is introduced into the process chamber and produces a
monolayer of gas on the wafer surface. Then a second precursor of gas is introduced monolayer of gas on the wafer surface. Then a second precursor of gas is introduced
into the chamber reacting with the first precursor to produce a monolayer of film on into the chamber reacting with the first precursor to produce a monolayer of film on
the wafer surface.the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech "Atomic Layer Deposition," Cambridge NanoTech
Inc., 24 April 06. <Inc., 24 April 06. <http://www.cambridgenanotech.com/
>.>.

15. ALD Process and ALD Process and
EquipmentsEquipments
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition (Step 2b) deposition (Step 2b)
•Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a A first precursor gas is introduced into the process chamber and produces a
monolayer of gas on the wafer surface. Then a second precursor of gas is introduced monolayer of gas on the wafer surface. Then a second precursor of gas is introduced
into the chamber reacting with the first precursor to produce a monolayer of film on into the chamber reacting with the first precursor to produce a monolayer of film on
the wafer surface.the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech "Atomic Layer Deposition," Cambridge NanoTech
Inc., 24 April 06. <Inc., 24 April 06. <http://www.cambridgenanotech.com/
>.>.

16. ALD Process and ALD Process and
EquipmentsEquipments
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition (Step 2c) deposition (Step 2c)
•Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a A first precursor gas is introduced into the process chamber and produces a
monolayer of gas on the wafer surface. Then a second precursor of gas is introduced monolayer of gas on the wafer surface. Then a second precursor of gas is introduced
into the chamber reacting with the first precursor to produce a monolayer of film on into the chamber reacting with the first precursor to produce a monolayer of film on
the wafer surface.the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech "Atomic Layer Deposition," Cambridge NanoTech
Inc., 24 April 06. <Inc., 24 April 06. <http://www.cambridgenanotech.com/
>.>.

17. ALD Process and ALD Process and
EquipmentsEquipments
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition (after 3 cycles) deposition (after 3 cycles)
•Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a A first precursor gas is introduced into the process chamber and produces a
monolayer of gas on the wafer surface. Then a second precursor of gas is introduced monolayer of gas on the wafer surface. Then a second precursor of gas is introduced
into the chamber reacting with the first precursor to produce a monolayer of film on into the chamber reacting with the first precursor to produce a monolayer of film on
the wafer surface.the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech "Atomic Layer Deposition," Cambridge NanoTech
Inc., 24 April 06. <Inc., 24 April 06. <http://www.cambridgenanotech.com/
>.>.

18. ALD Process and ALD Process and
EquipmentsEquipments
•Releases sequential precursor gas pulses to deposit a film one layer at a time.Releases sequential precursor gas pulses to deposit a film one layer at a time.
•A first precursor gas is introduced into the process chamber and produces a monolayer of A first precursor gas is introduced into the process chamber and produces a monolayer of
gas on the wafer surface. Then a second precursor of gas is introduced into the chamber gas on the wafer surface. Then a second precursor of gas is introduced into the chamber
reacting with the first precursor to produce a monolayer of film on the wafer surface.reacting with the first precursor to produce a monolayer of film on the wafer surface.
Two fundamental mechanisms:Two fundamental mechanisms:
Chemisorption saturation processChemisorption saturation process
Sequential surface chemical reaction processSequential surface chemical reaction process
•Example: ALD cycle for AlExample: ALD cycle for Al
22OO
33 deposition deposition
•Since each pair of gas Since each pair of gas
pulses (one cycle) produces pulses (one cycle) produces
exactly one monolayer of exactly one monolayer of
film, the thickness of the film, the thickness of the
resulting film may be resulting film may be
precisely controlled by the precisely controlled by the
number of deposition number of deposition
cycles.cycles.
Ref:Ref: "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. < "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. <www.
icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf>.>.
Step coverage and deposition rate Vs. Step coverage and deposition rate Vs.
deposition technique.deposition technique.

19. ALD Process and ALD Process and
EquipmentsEquipments
Four main types of ALD reactorsFour main types of ALD reactors
•Closed system chambersClosed system chambers
•Open system chambersOpen system chambers
•Semi-closed system chambersSemi-closed system chambers
•Semi-open system chambersSemi-open system chambers

20. ALD Process and ALD Process and
EquipmentsEquipments
Four main types of ALD reactorsFour main types of ALD reactors
•Closed system chambers (most common)Closed system chambers (most common)
•Open system chambersOpen system chambers
•Semi-closed system chambersSemi-closed system chambers
•Semi-open system chambersSemi-open system chambers


21. ALD Process and ALD Process and
EquipmentsEquipments
Four main types of ALD reactorsFour main types of ALD reactors
•Closed system chambers Closed system chambers (most common)(most common)
The reaction chamber walls are designed to effect the The reaction chamber walls are designed to effect the
transport of the precursors.transport of the precursors.
•Open system chambersOpen system chambers
•Semi-closed system chambersSemi-closed system chambers
•Semi-open system chambersSemi-open system chambers
Schematic of
a closed ALD
system
Ref:Ref: "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April
06. <06. <
www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf
>.>.

22. ALD Process and ALD Process and
EquipmentsEquipments
The Verano 5500™
A 300-mm ALD system by
Aviza Technology, Inc [2].
Process Temperature [1]
[1] [1]
11
"Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. < "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. <
www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf
>>
22
”Atomic Layer Deposition," Aviza Technology. 26 April 06. ”Atomic Layer Deposition," Aviza Technology. 26 April 06.
<<http://www.avizatechnology.com/products/verano.shtml
>.>.

23. ALD Process and ALD Process and
EquipmentsEquipments
The Verano 5500™
A 300-mm ALD system by
Aviza Technology, Inc [2].
One cycle
Process Temperature [1]Process Temperature [1]
[1] [1]
Acceptable
temperature range
for deposition.
11
"Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. < "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. <
www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf >.>.
22
”Atomic Layer Deposition," Aviza Technology. 26 April 06. ”Atomic Layer Deposition," Aviza Technology. 26 April 06.
<<http://www.avizatechnology.com/products/verano.shtml
>.>.

24. ALD ApplicationsALD Applications
•High-K dielectrics for CMOSHigh-K dielectrics for CMOS
•Semiconductor memory (DRAM)Semiconductor memory (DRAM)
•Cu interconnect barrierCu interconnect barrier
•Deposition in porous structuresDeposition in porous structures

25. ALD ApplicationsALD Applications
•High-K dielectrics for CMOSHigh-K dielectrics for CMOS
•Semiconductor memory (DRAM)Semiconductor memory (DRAM)
•Cu interconnect barrierCu interconnect barrier
•Deposition in porous structuresDeposition in porous structures


26. Candidates for High-K dielectricsCandidates for High-K dielectrics
FilmFilm PrecursorsPrecursors
AlAl
22OO
33Al(CH)Al(CH)
33, H, H
22O or OO or O
33
HfOHfO
22 HfClHfCl
44 or TEMAH, H or TEMAH, H
22OO
ZrOZrO
22 ZrClZrCl
44, H, H
22OO
ALD ApplicationsALD Applications
•High-K dielectrics for CMOSHigh-K dielectrics for CMOS
•Reduces leakage current
•Faster switching speed
•Cooler transistors
Ref: "Intel's High-k/Metal Gate Announcement," Intel
®
Corporation. 26 April,
06. <http://www.intel.com/technology/silicon/micron.htm#high>.

27. ALD ApplicationsALD Applications
•High-K dielectrics for CMOSHigh-K dielectrics for CMOS
•Semiconductor memory (DRAM)Semiconductor memory (DRAM)
•Cu interconnect barrierCu interconnect barrier
•Deposition in porous structuresDeposition in porous structures
All these applications take
advantage of uniformity,
conformal step coverage,
precise thickness control
of deposited films, which
can be achieved by ALD
deposition method.
Step coverage and deposition rate Vs. Step coverage and deposition rate Vs.
deposition technique.deposition technique.
Ref:Ref: "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April
06. <06. <
www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf
>.>.

28. SummarySummary
•AdvantagesAdvantages
Stoichiometric films with large area uniformity and 3D Stoichiometric films with large area uniformity and 3D
conformality.conformality.
Precise thickness control.Precise thickness control.
Low temperature deposition possible.Low temperature deposition possible.
Gentle deposition process for sensitive substrates.Gentle deposition process for sensitive substrates.
•DisadvantagesDisadvantages
Deposition Rate slower than CVD.Deposition Rate slower than CVD.
Number of different material that can be deposited is fair Number of different material that can be deposited is fair
compared to MBE.compared to MBE.