Enhanced radiation tolerance. No substrate diodes, inputs more difficult to protect. Density of contemporary digital processes is actually determined by number and density of metal interconnection layers. Sapphire and silicon on SiO 2 substrates are considerably more expensive. Eases automated routing and improves power and clock distribution to modules.
Aggressive processes allow the stacking of vias on top of contacts.
Silicide used to make direct connection between poly and diffusion, no contact or metal. Trench capacitors allow memory densities of 64Mbit and higher. Design rules specify geometric constraints on the layout artwork. Provide a communication channel between the IC designer and the fabrication process engineer. To minimize the area of the circuit.