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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
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In integrated circuits (ICs), conductive lines provide electrical interconnection among different parts of the ICs, devices, and the outside. The main applications of metallization are classified by gate, contact, and interconnection. Polysilicon and silicides are commonly applied as gates and interconnects in MOS devices. Aluminum, copper, tungsten, silver, titanium, platinum, gold, and palladium are used as these types of contacts, connections, and/or interconnection to external components.
Table 2033a. Properties of some metals commonly used in ICs.
Property\metal |
Cu |
Al |
W |
Au |
Ag |
Resistivity (10-6 Ω•cm) |
1.67 |
2.66 |
5.65 - 15 |
2.35 |
1.59 |
Melting point (°C) |
1085 |
660 |
3387 |
1064 |
962 |
Thermal conductivity (Wcm-1) |
3.98 |
2.358 |
1.74 |
3.15 |
4.25 |
Thermal stress per degree for
films on silicon (107 dyn cm-2 °C-1) |
2.5 |
2.1 |
0.8 |
1.2 |
1.9 |
Coefficient of thermal expansion (CTE)
(10-6 °C-1) |
17 |
23.5 |
4.5 |
14.2 |
19.1 |
Youngs modulus (x10-11 dyn cm-2) |
12.98 |
7.06 |
41.1 |
7.85 |
8.27 |
Corrosion in air |
Poor |
Good |
Good |
Excellent |
Poor |
Specific heat capacity(Jkg-1K-1) |
38 |
917 |
138 |
132 |
234 |
Adhesion to SiO2 |
Poor |
Good |
Poor |
Poor |
Poor |
Table 2033b. Metallization selections in ICs.
Application |
Selection |
Gates, interconnection, and
contacts |
Polysilicon, refractory metal silicides (e.g. MoSix, TaSix, WSix, and TiSix), nitrides, aluminum, copper, and/or refractory metals. |
Diffusion barrier layer |
Ti, TiN, Ta, TaN, Ti-W alloy, and/or silicides |
Top level |
Aluminum, and/or copper |
Metallization
on silicon |
Silicides, tungsten, aluminum, and/or copper |
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