High-k/metal gate (HKMG)
Beginner
A newer recipe for the gate: a special insulator and a metal electrode instead of glass and silicon, so the gate keeps control without leaking.
Novice
A gate stack that replaces silicon dioxide with a material of higher dielectric constant (‘high-k’, such as hafnium oxide) and the silicon gate electrode with metal. It allows a thinner equivalent insulator without a big jump in gate leakage.
Expert
Introduced at the 45 nm generation. High-k raises at a physical thickness that keeps direct tunneling down; the metal removes poly depletion and lets work-function metals set in undoped multigate channels.