Patent ID: 6495890
Filing Date: 2002-12-17
Classification: H01L

Abstract:
A field-effect transistor comprising:a semiconductor substrate; a gate insulation film formed selectively on the semiconductor substrate; a gate electrode layer formed on the gate insulation film; a source region and a drain region formed in surface portions of the semiconductor substrate along opposed ends of the gate electrode layer, the source region and the drain region having opposed end portions located below the gate electrode layer; and a channel region formed in a surface portion of the semiconductor substrate between opposed end portions of the source region and the drain region, a portion of the gate insulation film on at least one of the opposed end portions having a dielectric constant lower than that of the gate insulation film on the channel region, and the gate insulation film on the channel region being formed of a first material, and the portion of the gate insulating film on at least one of the opposed end portions being formed of a second material having a dielectric constant lower than that of the first material, and the first material containing at least one selected from the group consisting of titanium oxide, tantalum pentoxide, zirconium oxide, hafnium oxide, lanthanum oxide, aluminum oxide, yttrium oxide and scandium oxide.