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Atomic Layer Deposition (ALD)

Presented byPresented by

Myo Min TheinMyo Min Thein

EE 518 Class Presentation, Penn StateEE 518 Class Presentation, Penn State

Spring 2006Spring 2006Instructor: Dr. J. RuzylloInstructor: Dr. J. Ruzyllo

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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

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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 except that the ALD reaction breaks the CVD reaction into two half-reactions, keeping the precursor materials into two half-reactions, 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 reactions, which makes achieving atomic scale deposition control possible.deposition control possible.

• By keeping the precursors separate throughout the By keeping the precursors separate throughout the coating process, atomic layer thickness control of film coating process, atomic layer thickness control of film grown can be obtained as fine as atomic/molecular grown can be obtained as fine as atomic/molecular scale per monolayer.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>.>.

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Definition of ALDDefinition of ALD• ALD is a method of applying thin films to various ALD is a method of applying thin films to various

substrates with atomic scale precision.substrates with atomic scale precision.

• Similar in chemistry to CVD, except Similar in chemistry to CVD, except that the ALD reaction breaks the that the ALD reaction breaks the CVD reaction into two half-CVD reaction into two half-reactions, keeping the precursor reactions, keeping the precursor materials separate during the materials separate during the reaction.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 reactions, which makes achieving atomic scale deposition control possible.deposition control possible.

• By keeping the precursors separate throughout the By keeping the precursors separate throughout the coating process, atomic layer thickness control of film coating process, atomic layer thickness control of film grown can be obtained as fine as atomic/molecular grown can be obtained as fine as atomic/molecular scale per monolayer.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>.>.

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• ALD is a method of applying thin films to various ALD is a method of applying thin films to various substrates with atomic scale precision.substrates 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 except that the ALD reaction breaks the CVD reaction into two half-reactions, keeping the precursor materials into two half-reactions, keeping the precursor materials separate during the reaction.separate during the reaction.

• ALD film growth is ALD film growth is self-limited and based on surface reactions, which makes achieving which makes achieving atomic scale deposition control atomic scale deposition control possible.possible.

• By keeping the precursors separate throughout the By keeping the precursors separate throughout the coating process, atomic layer thickness control of film coating process, atomic layer thickness control of film grown can be obtained as fine as atomic/molecular grown can be obtained as fine as atomic/molecular scale per monolayer.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>.>.

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Definition of ALDDefinition of ALD• ALD is a method of applying thin films to various ALD is a method of applying thin films to various

substrates with atomic scale precision.substrates 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 except that the ALD reaction breaks the CVD reaction into two half-reactions, keeping the precursor materials into two half-reactions, 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 reactions, which makes achieving atomic scale deposition control possible.deposition control possible.

• By keeping the precursors separate By keeping the precursors separate throughout the coating process, throughout the coating process, atomic layer thickness control of film atomic layer thickness control of film grown can be obtained as fine as grown can be obtained as fine as atomic/molecular scale per atomic/molecular scale per monolayer.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>.>.

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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 Suntola and co-workers in Finland to improve the quality of ZnS films to improve the quality of ZnS films used in electroluminescent used in electroluminescent displays.displays.

• Recently, it turned out that ALD also produces Recently, it turned out that ALD also produces outstanding dielectric layers and attracts semiconductor outstanding dielectric layers and attracts semiconductor industries for making High-K dielectric materials.industries for 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>.>.

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Brief History of ALDBrief History of ALD• Introduced in 1974 by Dr. Tuomo Suntola and co-Introduced in 1974 by Dr. Tuomo Suntola and co-

workers in Finland to improve the quality of ZnS films workers in Finland to improve the quality of ZnS films used in electroluminescent displays.used in 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 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>.>.

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9ALD Process and ALD Process and EquipmentsEquipments

• Releases sequential precursor gas Releases sequential precursor gas pulses to deposit a film one layer pulses to deposit a film one layer at a time on the substrate.at a 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 precursor of gas is then introduced into the chamber reacting with the first precursor to produce a monolayer of film on the wafer the first precursor to produce a monolayer of film on the wafer surface.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 Al22OO33 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 monolayer of film, the thickness of the resulting film may be precisely controlled by the number of deposition cycles.precisely 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 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. Heterogeneous 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>.>.

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• 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 process chamber and produces a monolayer of gas on the wafer surface. Then a second of gas on the wafer surface. Then a second precursor of gas is introduced into the precursor of gas is introduced into the chamber reacting with the first precursor to chamber reacting with the first precursor to produce a monolayer of film on the wafer produce a monolayer of film on the wafer surface.surface.Two fundamental mechanisms: Chemisorption saturation process Sequential surface chemical reaction process

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 deposition deposition

• Since each pair of gas pulses (one cycle) produces exactly one monolayer of 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 film, the thickness of the resulting film may be precisely controlled by the number of deposition cycles.number of 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 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. Heterogeneous 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>.>.

4/25/06 EE 518 Class Presentation

11ALD Process and ALD Process and EquipmentsEquipments

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 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 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

Ref:Ref: "Atomic Layer Deposition," Cambridge NanoTech "Atomic Layer Deposition," Cambridge NanoTech Inc., 24 April 06. <Inc., 24 April 06. <http://www.cambridgenanotech.com/>.>.

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• 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

ALD Process and ALD Process and EquipmentsEquipments

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 deposition (Step 1b) deposition (Step 1b)

Ref:Ref: "Atomic Layer Deposition," Cambridge "Atomic Layer Deposition," Cambridge NanoTech Inc., 24 April 06. <NanoTech Inc., 24 April 06. <http://www.cambridgenanotech.com/>.>.

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13ALD Process and ALD Process and EquipmentsEquipments

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 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 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

Ref:Ref: "Atomic Layer Deposition," Cambridge "Atomic Layer Deposition," Cambridge NanoTech Inc., 24 April 06. <NanoTech Inc., 24 April 06. <http://www.cambridgenanotech.com/>.>.

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14ALD Process and ALD Process and EquipmentsEquipments

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 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 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

Ref:Ref: "Atomic Layer Deposition," Cambridge "Atomic Layer Deposition," Cambridge NanoTech Inc., 24 April 06. <NanoTech Inc., 24 April 06. <http://www.cambridgenanotech.com/>.>.

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15ALD Process and ALD Process and EquipmentsEquipments

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 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 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

Ref:Ref: "Atomic Layer Deposition," Cambridge "Atomic Layer Deposition," Cambridge NanoTech Inc., 24 April 06. NanoTech Inc., 24 April 06. <<http://www.cambridgenanotech.com/http://www.cambridgenanotech.com/>.>.

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16ALD Process and ALD Process and EquipmentsEquipments

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 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 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

Ref:Ref: "Atomic Layer Deposition," Cambridge "Atomic Layer Deposition," Cambridge NanoTech Inc., 24 April 06. NanoTech Inc., 24 April 06. <<http://www.cambridgenanotech.com/http://www.cambridgenanotech.com/>.>.

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17ALD Process and ALD Process and EquipmentsEquipments

• Example: ALD cycle for AlExample: ALD cycle for Al22OO33 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 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

Ref:Ref: "Atomic Layer Deposition," Cambridge "Atomic Layer Deposition," Cambridge NanoTech Inc., 24 April 06. NanoTech Inc., 24 April 06. <<http://www.cambridgenanotech.com/http://www.cambridgenanotech.com/>.>.

4/25/06 EE 518 Class Presentation

18ALD 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 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 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 introduced into the chamber 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: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 Al22OO33 deposition deposition

• Since each pair of gas Since each pair of gas pulses (one cycle) pulses (one cycle) produces exactly one produces exactly one monolayer of film, the monolayer of film, the thickness of the resulting thickness of the resulting film may be precisely film may be precisely controlled by the number controlled by the number of deposition cycles.of deposition 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.

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19ALD 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

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20ALD Process and ALD Process and EquipmentsEquipments

Four main types of ALD reactorsFour main types of ALD reactors• Closed system chambers (most Closed system chambers (most

common)common)• Open system chambersOpen system chambers• Semi-closed system chambersSemi-closed system chambers• Semi-open system chambersSemi-open system chambers

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21ALD Process and ALD Process and EquipmentsEquipments

Four main types of ALD reactorsFour main types of ALD reactors

• Closed system chambers Closed system chambers (most (most common)common) The reaction chamber walls are designed to effect The reaction chamber walls are designed to effect

the transport of the precursors.the 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 "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. <April 06. <www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf>.

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22ALD 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 "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. <www.icknowledge.com/misc_technology/Atomic%20LayerApril 06. <www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf>%20Deposition%20Briefing.pdf> 22 ”Atomic Layer Deposition," Aviza Technology. 26 ”Atomic Layer Deposition," Aviza Technology. 26

April 06. April 06. <<http://www.avizatechnology.com/products/verano.shthttp://www.avizatechnology.com/products/verano.shtmlml>.>.

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23ALD 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<www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf>.%20Briefing.pdf>. 22 ”Atomic Layer Deposition," Aviza Technology. 26 ”Atomic Layer Deposition," Aviza Technology. 26

April 06. April 06. <<http://www.avizatechnology.com/products/verano.shthttp://www.avizatechnology.com/products/verano.shtmlml>.>.

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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

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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

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Candidates for High-K dielectricsCandidates for High-K dielectricsFilmFilm PrecursorsPrecursors

AlAl22OO33 Al(CH)Al(CH)33, H, H22O or OO or O33

HfOHfO22 HfClHfCl44 or TEMAH, H or TEMAH, H22OO

ZrOZrO22 ZrClZrCl44, H, H22OO

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>.

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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 "Technology Backgrounder: Atomic Layer Deposition," IC Knowledge LLC, 24 April 06. <www.icknowledge.com/misc_technology/Atomic%20LayerApril 06. <www.icknowledge.com/misc_technology/Atomic%20Layer%20Deposition%20Briefing.pdf>.%20Deposition%20Briefing.pdf>.

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SummarySummary• AdvantagesAdvantages

Stoichiometric films with large area uniformity and Stoichiometric films with large area uniformity and 3D conformality.3D 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 Number of different material that can be deposited is

fair compared to MBE.fair compared to MBE.