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? ? ? conan_at_donga.ac.kr
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2
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IC or VLSI
Transistor
Vacuum tube
Materials Processing Laboratory
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Oxidation
Lithography
Etching
Diffusion
Deposition
Epi growth
Annealing
Ion implantation(doping)
Materials Processing Laboratory
5
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PVD Physical Vapor Depostion
CVD Chemical Vapor Deposition
Thermal evaporation
Thermal CVD
DC or RF sputtering
Low pressure CVD
Ion Beam sputtering
Plasma enhanced CVD
Pulsed Laser Depostion
Metal-organic CVD
Molecular beam epitaxy
Materials Processing Laboratory
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Physical properties are no longer same as those
of bulk
High surface to volume ratio
Existence of surface energy states
Different crystal structure
Different inter-atomic distance
Materials Processing Laboratory
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Evaporation
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Evaporation
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Sputter
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DC sputter
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RF sputter
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Time
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Magnetron sputter
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DCRF Magnetron sputter
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Ion beam sputter
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Sputter vs. evaporation
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Comparison of evaporation and sputtering
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Pulsed laser deposition
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Molecular beam epitaxy
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• evaporation at very low deposition rates
• typically in UHV
• very well controlled
• grow films with good crystal structure
• expensive
• often use multiple sources to grow alloy films
• deposition rate is so low that substrate
  temperature does not need to be as high

Materials Processing Laboratory
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PVD Summary
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Cost evaporation lt sputtering lt PLD lt MBE
Film quality evaporation lt sputtering lt PLD lt
MBE
Growth rate evaporation gt sputtering gt PLD gt MBE
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Chemical vapor deposition
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CVD overview (I)
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Reacts on substrate to deposit film
Not all components are found in all CVD systems
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CVD overview (II)
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Types of CVD reactions
Pyrolysis thermal decomposition
Reduction

• Advantages
• high growth rates possible
• can deposit materials which are hard to
  evaporate
• can grow epitaxial films
• Disadvantages
• high temperatures
• complex processes
• toxic and corrosive gasses

Oxidation
Compound formation
Disproportionation
Reversible transfer
Materials Processing Laboratory
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Low pressure CVD
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• Gas pressure 1 mtorr 1 torr ( lt 1 atm )
• Lower P gt higher D of gas to substrates
• ltAdvantagesgt
• Better film uniformity
• Better film coverage over steps
• Fewer defects

Materials Processing Laboratory
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Plasma enhanced CVD
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• Plasma breaks up gas molecules
• Higher reactivity
• can use lower temperatures
• can use lower pressures

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MOCVD
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NMOS transistor
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• Thermal oxidation
• Nitride deposition by LPCVD
• Active area mask and etching
• Boron implant
• Thermal oxidation
• Remove nitride and oxide pad
• Regrow thin gate oxide
• Boron threshold adjustment implant
• CVD polysilicon deposition
• Gate definition
• Source/drain implantation
• Source/drain diffusion
• CVD oxide deposition
• Contact openings
• Metal deposition
• Pattern metal
• Etch metal
• Passivation layer deposition
• Open bonding pads

Materials Processing Laboratory