Full custom VLSI technology

Full-custom VLSI is an IC technology in which the designer controls the layout of every transistor and interconnect, and all mask layers are made specifically for that chip.

• Design flow: specification, logic and circuit design, transistor sizing, manual layout (polygons for diffusion, poly, metal), design-rule check, extraction and simulation, mask generation, fabrication and test.
• Advantages: highest speed, lowest power, smallest area, lowest unit cost at very high volume, analog/digital mix possible.
• Disadvantages: very high NRE cost, long design time, needs expert layout engineers, errors require new masks, no change after fabrication.
• Applications: microprocessors, memories, high-volume consumer chips.