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