FILM DEPOSITION

1 MARCH 2017

NANOTECHNOLOGY

PRESENTATION

Pedro C. Feijoo

E-mail: PedroCarlos.Feijoo@uab.cat

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FILM GROWTH

Chemical vapor deposition (CVD)/Vapor phase epitaxy (VPE)

Atmospheric pressure CVD (APCVD)

Low pressure CVD (LPCVD)

Metal organic chemical vapor deposition (MOCVD)

Plasma enhanced chemical vapor deposition (PECVD)

Atomic layer deposition (ALD)

Physical vapor deposition (PVD)

Evaporation

Sputtering

Pulsed laser deposition/Laser sputtering/Laser ablation deposition (PLD)

Molecular beam epitaxy (MBE)

Electrochemical forming

Electrodeposition

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OUTLINE

1. CONCEPTS

2. TYPES OF TECHNIQUES

3. TECHNIQUES

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CONCEPTS

1. Epitaxial growth and Strain

Epitaxial growth: CVD and MBE

2. Step coverage

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Conformal film Non-conformal film

3. Plasma is a excited and ionized

gas. It appears when there is an

intense electric field that crosses

a gas, especially when the

pressure is low.

• Ionized particles are more prone to react.

• Ionized particles are accelerated by the electric field.

CONCEPTS

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FILM GROWTH CLASSIFICATION

ChemicalVapor Deposition (CVD)

Atoms react at the substrate

surface, reaching there by diffusive-

convective mass transfer.

Physical Vapor Deposition (PVD)

The material is deposited by

direct line-of-sight impigement

from a source.

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FILM GROWTH CLASSIFICATION

Electrochemical forming

It occurs inside an electrolytic

cell.

A bias is imposed.

Disolved ions deposit on the wafer

surface.

https://youtu.be/OxhCU_jBiOA?t=2m2

5s

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ATMOSFERIC PRESSURE CVD (APCVD)

100 – 10 kPa (1 atm = 101 325 Pa)

Substrate temperatures: 300-450°C

(low T) or >850°C (high T) for

epitaxies.

Simple, high deposition rate and low

temperatures

Poor step coverage and

contamination

Used to deposit Si or SiO2 on Si.

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LOW PRESSURE CVD (LPCVD)

100 – 10 Pa (10-3 – 10-4 atm)

Substrate temperatures: 550-650°C

(moderate).

Pure and uniform films, step

coverage, large wafer capacity

Low deposition rate

Used to deposit poly-Si, Si3N4, W,

SiO2…

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PLASMA ENHANCED CVD (PECVD)

200 – 700 Pa (10-3 atm)

Substrate temperatures: 200-400°C (low).

Low temperatures, fast, adhesion, step coverage and low pinhole

Contamination and plasma damage

Used to deposit Si3N4, insulators over metal...

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METAL ORGANIC CVD (MOCVD)

Use of metal-organic gases

Epitaxies over large areas

Highly toxic and expensive gases.

Very important industrial technique.

Used to compound semiconductors,

like AlGaAs on GaAs substrate.

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AsH3 = arsine

DEZn = Zn(C2H5)2

TMGa = Ga(CH3)3

TMAl = Al(CH3)3

METAL ORGANIC CVD (MOCVD)

MOCVD (2/2)

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ATOMIC LAYER DEPOSITION

In ALD, the reaction at the wafer surface takes place in two steps: sequential deposition of individual monolayers.

Each step saturates so one monolayer is deposited after cycle.

Substrate temperatures: ~400°C

Thickness, step coverage and composition control up to the atomic level

Slowness

Very thin and with low density of defects films.

https://youtu.be/HUsOMnV65jk?t=26s

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EVAPORATION

~ 0.01 Pa

Simple and low cost.

Bad adhesion

Used typically for metallic elements

(Al, Ti, Ag, Au…)

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SPUTTERING

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Radiofrequency

Target

refrigeration

Gas inputVacuum

system

Target

Substrate

Substrate holder and heaterPlasma

SPUTTERING (2/2)

~0.01 Pa

Ar plasma

Simple and low cost, good adhesion

Slower deposition rate, difficult

control process, plasma damage

Also for compounds (Al2O3, Au, Cr,

Mo, SiO2, Si3N4…)

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PULSED LASER DEPOSITION (PLD) /LASER SPUTTERING/LASER ABLATION

~ 0.01 Pa

Short highly-energetic small-wavelength laser pulses erode the target.

A small amount goes from solid to plasma and it deposits at the substrate.

Complex compounds:

YBa2Cu3O7-x (high temperature superconductor)

Ca10(PO4)6(OH)2 (biocompatible material)

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MOLECULAR BEAM EPITAXY (MBE) (1/2)

Epitaxy

Ultra high vaccum: 10-9 Pa

Substrates: 400-800 °C

No contamination and good crystal

structure, high uniformity

Slow rates, expensive

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MOLECULAR BEAM EPITAXY (MBE) (2/2)

RHEED: Reflection high-energy electron diffraction

Thanks to ultra high vaccum

Allows the control of the thickness 20

ELECTRODEPOSITION OR ELECTROPLATING

The surface of the wafer must be

conductive and connected to the

power supply.

Cu atoms dissolved in the

electrolyte are deposited on the

wafer.

It is the base of the ‘damascene’

technology

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FILM GROWTH

Technique Application

APCVD Thick oxides

LPCVD Oxides, silicon nitride, polysilicon, W, WSi2

MOCVD Industrial production of epitaxial layers

PECVD Insulators over metals and passivation layers

ALD Monolayer control

Evaporation Metal element:Ag Al Au Cr Cu Mo W…

Sputtering Al2O3 Au Cr Mo SiO2 Si3N4 TiC TiN…

PLD Complex compounds: YBa2Cu3O7-x, Ca10(PO4)6(OH)2…

MBE Epitaxial growth

Electrochemical

forming

Cu for interconections in ICs 22

REFERENCES

Fundamentals of microfabrication and nanotechnology, volumen 2: Manufacturing techniques for microfabrication and nanotechnology. 3rd edition. Marc J. Madou. CRC Press 2012. ISBN: 978-1-4200-5519-1

Fundamentals of semiconductor fabrication. Gary S. May and Simon M. Sze. John Wileyand Sons, Inc 2004. ISBN: 0-471-23279-3

Overview of the Use of Copper Interconnects in the Semiconductor Industry. Annabelle Pratt http://www.advanced-energy.com/upload/File/White_Papers/SL-ELECTROPLATING-270-01.pdf

Some figures were extracted from https://en.wikipedia.org

http://www.gan.msm.cam.ac.uk/facilities/mocvd/

http://webstaff.itn.liu.se/~qinzh/MOCVD

http://www.dowcorning.com/content/etronics/etronicschem/etronics_newcvd_tutorial3.asp

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