Vacuum tube

Transistor

IC or VLSI

Materials Processing Laboratory

전자소자의 발전과정

박막형 집적회로 구조

Materials Processing Laboratory

Materials Processing Laboratory

Oxidation

Lithography

Etching

Diffusion

Deposition

Ion implantation(doping)

Annealing

Epi growth

박막형 집적회로 제작

Materials Processing Laboratory

박막 증착 공정

PVD : Physical Vapor Depostion CVD : Chemical Vapor Deposition

Thermal evaporation

DC or RF sputtering

Pulsed Laser Depostion

Ion Beam sputtering

Thermal CVD

Plasma enhanced CVD

Metal-organic CVD

Molecular beam epitaxy

Low pressure CVD

Materials Processing Laboratory

박막의 특성

High surface to volume ratio

Physical properties are no longer same as those of bulk

Existence of surface energy states

Different crystal structure

Different inter-atomic distance

Materials Processing Laboratory

Evaporation 박막 증착 공정

Materials Processing Laboratory

Evaporation 박막 증착 공정

Materials Processing Laboratory

Sputter 박막 증착 공정

Materials Processing Laboratory

DC sputter 박막 증착 공정

Materials Processing Laboratory

RF sputter 박막 증착 공정

target - - - + - - - + -

substrate + chamber

+ + + - + + + - +

Time

Materials Processing Laboratory

Magnetron sputter 박막 증착 공정

Materials Processing Laboratory

DC&RF Magnetron sputter 박막 증착 공정

Materials Processing Laboratory

Ion beam sputter 박막 증착 공정

Materials Processing Laboratory

Sputter vs. evaporation 박막 증착 공정

EVAPORATION SPUTTERING

low energy atoms higher energy atoms

high vacuum path•few collisions •line of sight deposition •little gas in film

low vacuum, plasma path•many collisions •less line of sight deposition •gas in film

larger grain size smaller grain size

fewer grain orientations

many grain orientations

poorer adhesion better adhesion

Comparison of evaporation and sputtering

Materials Processing Laboratory

Pulsed laser deposition 박막 증착 공정

Materials Processing Laboratory

Molecular beam epitaxy 박막 증착 공정

• 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

PVD Summary 박막 증착 공정

Cost : evaporation < sputtering < PLD < MBE

Film quality : evaporation < sputtering < PLD < MBE

Growth rate : evaporation > sputtering > PLD > MBE

Chemical vapor deposition

Materials Processing Laboratory

CVD overview (I) 박막 증착 공정

Reacts on substrate to deposit film

Not all components are found in all CVD systems

Materials Processing Laboratory

CVD overview (II) 박막 증착 공정

Types of CVD reactions

Pyrolysis – thermal decomposition

Reduction

Oxidation

Compound formation

Disproportionation

Reversible transfer

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

Materials Processing Laboratory

Low pressure CVD 박막 증착 공정

Gas pressure : 1 mtorr – 1 torr ( < 1 atm )Lower P => higher D of gas to substrates

<Advantages>• Better film uniformity• Better film coverage over steps• Fewer defects

Materials Processing Laboratory

Plasma enhanced CVD 박막 증착 공정

Plasma breaks up gas molecules

• Higher reactivity• can use lower temperatures• can use lower pressures

Materials Processing Laboratory

MOCVD 박막 증착 공정

Materials Processing Laboratory

NMOS transistor 반도체제작공정 예

1. Thermal oxidation2. Nitride deposition by LPCVD3. Active area mask and etching4. Boron implant5. Thermal oxidation6. Remove nitride and oxide pad7. Regrow thin gate oxide8. Boron threshold adjustment implant9. CVD polysilicon deposition10. Gate definition11. Source/drain implantation12. Source/drain diffusion13. CVD oxide deposition14. Contact openings15. Metal deposition16. Pattern metal17. Etch metal18. Passivation layer deposition19. Open bonding pads