1. Film Deposition in IC Fabrication
Metal Contacts/Connections
Electrodes
Masks
Wire insulation
Device encapsulation
Low stress
Adherent
Uniformity, no pin holes
Conformal step coverage
Thermal & electrical stability

2. Vapor pressure of metals

3. Voltage ratio in RF sputtering: VC/VA = (AA/AC)n
Sputter Deposition Systems
RF Sputter System
Voltage ratio in RF sputtering: VC/VA = (AA/AC)n E
DC Sputter Deposition
Magnetron Sputter Deposition

4. Chemical Vapor Deposition (CVD)
Plasma-enhanced CVD (PECVD)
Low-pressure CVD (LPCVD)

5. Different thin film textures
Single crystal
Poly-crystalline
Poly-crystalline columnar
Nano-crystalline
amorphous

6. Step Coverage of Deposited Films
High surface mobility + non-directional flux  conformal step coverage

7. Electromigration Effects
Void Pile-up
Bamboo-structured wire
Electromigration-resistant
Electron wind and field-driven atomic migration

8. SiO2 Films for masking & protection
SiH4 + O2  SiO2 + 2H2 or SiH4 + N2O SiO2 + 2N2 + 2H2
by APCVD or LPCVD at ~ 450ºC, SiH4 diluted in H2
with Si(C2H5O)4 (TEOS), more stable to handle
Si(C2H5O)4 + 12O2  SiO2 + 8CO2 + 10H2O, APCVD or LPCVD at ~ 700ºC
SiO2 films by PECVD at ºC, low compressive stress.
Applications of deposited SiO2 films:
Field oxide for MOS and HV devices (deposited on thermal SiO2)
Fill-in of the isolation walls/wells
Isolation between multi-layer metal connections
Diffusion and implantation masks
Final encapsulation layer

9. Other Films for masking & protection
Phosphosilicate glass (PSG)
adding P2O5 to improve the quality of SiO2
mixing PH3 or (CH3O)3P in oxidation gases
2PH3 + 4O2  P2O5 + 3H2O
or 2(CH3O)3P + 10O2  P2O5 + 6CO2 + 10H2O
Effect of P2O5: reduce tensile stress in SiO2 (to 0 at ~ 20% P2O5)
TCE() matching with substrate (P2O5 raises )
improve film texture (denser, void-free)
effective diffusion barrier to Na
Si3N4 (and SiOxNy) more stable than SiO2, excellent barrier
to Na, B and Ga migration, mask for oxidation
3SiH4 + 4NH3  Si3N4 + 12H2 (PNH3 : PSiH4 ~ 150)
LPCVD at ~900ºC, high tensile stress, t < 1000Å
PECVD at ~300ºC, low stress, high H incorporation
RF sputtering of Si in N2 discharge: 3Si + 4N  Si3N4

10. High solubility of Si in Al (~1%)
Pit Formation of Al Contact with Si
High solubility of Si in Al (~1%)
Al spikes

11. Silicide Contacts Resistivity of metal 5.8 10.5 10.4 13 43 13 20 5.342 13
5.3
14.5 7
Resistivity of metal

12. Phase Diagram and Formation Sequence of Silicide
Oxidation of Silicide