Self-aligned gate

In semiconductor electronics fabrication technology, a self-aligned gate is a transistor manufacturing approach whereby the gate electrode of a MOSFET (metal–oxide–semiconductor field-effect transistor) is used as a mask for the doping of the source and drain regions. This technique ensures that the gate is naturally and precisely aligned to the edges of the source and drain.

The use of self-aligned gates in MOS transistors is one of the key innovations that led to the large increase in computing power in the 1970s. Self-aligned gates are still used in most modern integrated circuit processes.