Advances in high & kappa gate dielectrics for Si and III-V semiconductors

Nanoscale device technology is driving intense study of thin dielectric layers on semiconductors. The aggressive scaling of Si CMOS technology calls for identifying high /spl kappa/ dielectrics to replace SiO/sub 2/ and oxynitrides in gate related applications. The material, requirements for the alternative gate dielectric are very challenging in order to achieve performance comparable to SiO/sub 2/. Furthermore, there are demanding issues for process integration compatibility. Among several binary oxides proposed the rare earth oxides are attractive candidates based on thermodynamic energy considerations and a high conduction band offset over 2eV. The interest in the rare earth oxide stems from our earlier work on GaAs passivation. The Ga/sub 2-x/Gd/sub x/O/sub 3/ mixed oxides (/spl kappa/ =12) and the Gd/sub 2/O/sub 3/ oxides (/spl kappa/ =14) films grown by ultrahigh vacuum deposition from an oxide source formed an excellent insulating barrier with low interfacial state density D/sub it/ on the GaAs surface. This discovery has led to the first GaAs based inversion channel MOSFET devices. These dielectrics were also successfully applied to other III-V semiconductors including InGaAs, AlGaAs, InP, and GaN producing MOS diodes and MOSFETs.