High permittivity silicate gate dielectric

A field effect semiconductor device comprising a high permittivity silicate gate dielectric and a method of forming the same are disclosed herein. The device comprises a silicon substrate 20 having a semiconducting channel region 24 formed therein. A metal silicate gate dielectric layer 36 is formed over this substrate, followed by a conductive gate 38 . Silicate layer 36 may be, e.g., hafnium silicate, such that the dielectric constant of the gate dielectric is significantly higher than the dielectric constant of silicon dioxide. However, the silicate gate dielectric may also be designed to have the advantages of silicon dioxide, e.g. high breakdown, low interface state density, and high stability. The present invention includes methods for depositing both amorphous and polycrystalline silicate layers, as well as graded composition silicate layers.