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ZNO THIN FILM DEPOSITIONUSING MAGNETRON

SPUTTERING

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Overview

Thin film

Sputtering

Zinc Oxide thin film

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Thin film

Layer of material on a substrate less than about one

micron

Properties of Thin filmLower in density (compared to bulk material)

Under stress

Different defect structures from bulkStrongly influenced by surface and interface effects

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Steps in Thin film Growth

Emission of Particle from the source

Transport of the particle to the substrate

Condensation of particles on the substrate

Impinging

material

Desorption

Bulk

Diffusion

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Thin film Deposition Process

Solid

Liquid

Vapor

Gas

Source

Vacuum

Fluid

Plasma

Transport

Substratecondition

Reactivity ofsourcematerial

Energy input

Deposition

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1. Source

Physical Vapor Deposition Solid material need to be vaporized to transport them

into substrate

This can be done by heat or energetic beam of

Electrons (e-beam evaporation) Photons (Laser ablation)

Positive ions (Sputtering)

Chemical Vapor Deposition

Source materials Gases

Evaporating liquids

Chemically gasified solid

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2. Transport

Uniformity of arrival rate over the surface area

Factors affecting uniformity

High vacuum

Lowers melting point

Maintains purity

Increases mean free path of particles

Geometry

Fluid collisions Gas flow pattern

Diffusion of source molecules through other gasespresent

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3. Deposition

Substrate surface condition

Roughness

Level of contamination

Degree of chemical bonding with arriving material

Reactivity of the arriving material

Probability of arriving material reacting with thesurface and becoming incorporated into the film

Energy input Substrate energy

Photons in Laser assisted deposition

Positive ion beams

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Types of Thin film

High Quality Thin film Low Quality Thin film

Slow deposition rate High deposition rate

High vacuum Low vacuum

High substrate temperature Low substrate temperature

Single crystalline Poly crystalline

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Applications of Thin film

Thin film Property Category

Typical Applications

Optical Reflective/antireflective coatings

Decorative coatings

Memory discs

Wave guide

Electrical Insulation

ConductionSemiconductor devices

Piezo-electric devices

Magnetic Memory discs

Spintronics

Chemical Barriers to diffusion/alloying

Protection against oxidation/corrosionGas/Liquid sensors

Mechanical Wear-resistant coatings

Hardness

Adhesion

Thermal Barrier layers

Heat sinks

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Zinc Oxide Thin films

II-IV compound semiconductor

Band gap3.4 eV

Crystal structureHexagonal

a=0.325 nm b=0.521 nm

Applications Thin film transistors

UV light emitters Chemical sensors

Piezo electric devices

Sprintronics

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Synthesis

Vapor Transport Synthesis

Zno & Oxygen

Decomposition of ZnO

Heating Zn powder under Oxygen flow

Indirect Method (Organometallic Vapor Phase

Epitaxy)

Di-ethyl Zinc & Oxygen

Carbothermal Method

ZnO & Graphite

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Sputtering

Ion impact setup a series of collisions between the atoms of the target

Which leads to ejection of atoms from the target called sputtering

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Sputter Yield

Sputter yield (S) =Ejected atoms or molecules

Incident ion

S values are typically in the range of 0.01 and 4 and increase with themass of metals and energy of the sputtering gas.