The designer of well-defined Al (rho Al = 3.2 mu ohm-cm) connector deposited on
ID: 1489210 • Letter: T
Question
The designer of well-defined Al (rho Al = 3.2 mu ohm-cm) connector deposited on SiO_2 as an insulator (sigma r,SiO_2 = 3.9) and got an excellent result in RC delay 1.1 ps. a) Transferring the design when using silicon nitride, Si_3N_4 (sigma r,Si_3N_4 = 7.5) as would be done in a Gallium Nitride device processing, the result was not encouraging. Explain the result b) However when same connector was made of Cu (rho Cu = 1.7 mu ohm-cm) and SiO_2 is used as an insulator the result was satisfactory. Explain the resultExplanation / Answer
Copper (Cu) has higher conductivity and resistance to electromigration (EM) than aluminum (Al) and has been the choice of the semiconductor industry for interconnecting metal in sub-100 nm devices. With rapidly decreasing feature sizes and more demand for circuit speed, low-K and passivation materials have been inserted with Cu-interconnects to address the additional RC delay reduction.
Silicon nitride has higher resistivity and dielectric strength than most insulators commonly available in microfabrication (1016 ·cm and 10 MV/cm, respectively).
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Dielectrics or electrically insulated materials are understood as materials in which electrostatic fields could persist for a long time. The materials offer a very high resistance to the passage of electric current, and have been used as thin films in electronic circuits. In conventional silicon planar devices, deposition of resistors, capacitors, and their connections are made on stable insulating substrates like silicon dioxide (SiO2). Thin insulating dielectric films are used in a wide variety of components. The films are usually amorphous or near amorphous in nature and they show higher electrical resistance compared to polycrystalline or crystalline thin films. In integrated circuit (IC) dielectric materials are used as insulating layers between conducting layers, diffusion and ion implantation masks, capping material for doped films to prevent loss of dopants, passivation layers to protect devices from impurities, moisture and scratches, sandwich material between two electrodes to form a capacitor, and gate oxide