Structure Design,Interface Instability Control And Performance Optimization Of High-k Gate Dielectric/Gallium Antimonide MOS Devices

With the scaling down of CMOS technology nodes gradually coming to an end,new devices in the post-Moore era will influence and determine the future development of microelectronic device technology and the pattern of the integrated circuit industry.The thickness of conventional Si O₂ gate dielectrics have reached their physical limit,and the quantum tunneling effect has greatly affected the stability of MOS devices and the development of low-power and high-performance electronic devices.When maintaining or reducing the equivalent thickness,the high-k material can significantly increase the physical thickness of dielectric layers to effectively suppress the generation of tunneling current.Therefore,it has become an inevitable trend to replace the traditional Si O₂ in the development of microelectronics technology.When satisfying the selection requirements of high-k gate dielectrics,the rare-earth Yb₂O₃ material has attracted extensive attention from scientific researchers owing to its higher crystallization temperature,phase stability and fewer oxygen vacancy defects.Silicon-based semiconductor materials cannot meet the semiconductor industry's demand for high driving capability due to its inherent low electron mobility properties.Integrated circuits require using high-mobility channel materials to enhance the control of the gate voltage on the channel conductance in a small size.Therefore,the integration of high-k dielectrics and III-V Ga Sb MOS devices has the characteristics of high carrier mobility and low gate leakage,which is of great significance in enabling integrated circuit technology to continue to develop along Moore's Law.A huge challenge for III-V semiconductor materials is that the materials are easily oxidized and their oxides are complex and unstable.Therefore,obtaining high-quality Yb₂O₃ gate dielectric films and reducing the interface state density between the gate dielectric and Ga Sb have become the key to promoting the wider application of III-V semiconductors in CMOS processes.This thesis article mainly focuses on these key scientific issues to explore the Yb₂O₃ film preparation process and Ga Sb interface optimization.The specific research content and results are as follows:(1)In this dissertation,the ytterbium oxide films were prepared based on magnetron sputtering technology,and the effects of sputtering power and annealing temperature on the crystal structure,optical properties and interface chemistry of the thin film were explored.An Al/Yb₂O₃/Si MOS capacitor was constructed based on the ytterbium oxide film,and its electrical characteristics were tested and analyzed,as well as the preparation parameters of the high-quality Yb₂O₃ film were determined.The results show that the films prepared at 20 W exhibit the best optical properties,with a refractive index of 1.70 and a transmittance of up to93%.The film treated by rapid thermal annealing at 400?begins to crystallize into a cubic phase,and the interface oxide and Silicate annealed at 300?reduces and has the smallest leakage current density(3.66×10^-8 A/cm²).The above results show that proper annealing treatment can effectively reduce the generation of interface oxides,thereby obtaining high-quality gate dielectric films with optimized electrical properties.(2)A new interface passivation method for Ga Sb-based MOS capacitors was proposed,and the effects of(NH₄)₂S solutions with different p H values on the interface and electrical properties of the Al/Yb₂O₃/Ga Sb MOS structure were discussed.The interface analysis shows that the sulfur passivation treatment can reduce the surface roughness of Ga Sb,and the neutralized(NH₄)₂S can effectively reduce the corrosiveness of the solution to obtain a relatively flat surface.The neutral(NH₄)₂S solution passivation treatment can effectively reduce the solubility of Ga and Sb related sulfides in the solution,thereby forming a thicker sulfur protective layer on the Ga Sb surface,which can effectively remove unstable oxides between the interface.The electrical analysis shows that sulfur passivation treatment can optimize the capacitance-voltage characteristics of the Al/Yb₂O₃/Ga Sb MOS structure and effectively reduce the interface state density of the channel layer(?35%).(3)Based on sputtering and ALD technology,Yb₂O₃ gate dielectrics and ultra-thin Al₂O₃passivation layers were prepared respectively,and three stacked structures(Yb₂O₃/A1₂O₃,A1₂O₃/Yb₂O₃ and A1₂O₃/Yb₂O₃/A1₂O₃)were prepared.The effects of gate dielectric layers with different stacking sequences on the interface and electrical characteristics of Ga Sb-MOS devices were studied.The results show that the Yb₂O₃/Al₂O₃/Ga Sb laminated structure achieves the best interface chemical distribution and high-quality film.This is mainly due to the Al₂O₃layer's anti-oxygen diffusion properties effectively inhibiting the inter-diffusion between interfaces induced by gate dielectrics deposition,and the thermal decomposition of unstable oxide caused by the secondary deposition of Al₂O₃ layer is avoided.The Yb₂O₃/Al₂O₃/Ga Sb laminated structure achieves the smallest leakage current density(2.25×10^-7 A/cm²),the largest dielectric constant(14.14)and trap energy level(0.65 e V).It provides a potential substitute material for the CMOS process,and is of great significance to the development of the III-V compounds with high mobility in the field of low power consumption and high performance microelectronics.