High-k

The term high-k dielectric refers to a material with a high dielectric constant (k) (as compared to silicon dioxide) used in semiconductor manufacturing processes which replaces the silicon dioxide gate dielectric. The implementation of high-k gate dielectrics is one of several strategies developed to allow further miniaturization of microelectronic components, colloquially referred to as extending Moore's Law.
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a dielectric material with a dielectric constant greater than the dielectric constant of silicon dioxide, k>4. As minimum feature sizes have shrunk it has been necessary to shrink the thickness is gate oxides in proportion. Gate oxides are now becoming so thin that they do not display sufficiently good insulating properties. High-k materials can in theory replace silicon dioxide as a gate insulator, be used at a greater thickness, the higher the dielectric constant the thicker the film that can be used, and still adequately control the channel region.