Thin-Film Deposition
to connect device structures to the “ outside world” requires the deposition and patterning of a metal layer. In fact , complex ICs have three and sometime four electrically isolated metallization layers. Electrical isolation of the metal layers in turn requires the deposition of intervening dielectric layers. Thin films are also deposit to prevent the interdiffusion of materials and to protect the device or circuit from contamination . In –use methods for depositing the required film are reviewed next.
Evoporation
Evoporation is one of the older and more straightforward methords of thin -film deposition. As envisiones in Fig. 4.12, the material to be evaporated is placed in or on a resistance heated
source holder inside a vacuum chamber. To evaporate AL, for example, a short piece of AL wire would be place on a tungsten or boat. The substrate on with the film is to be deposited is also positioned inside the chamber facing the source