Based On Hfo < Sub > 2 < / Sub > - The Sio < Sub > 2 < / Sub > Medium Density Mim Capacitor Research

High density metal-insulator-metal(MIM)capacitors have attracted great attention for radio-frequency and mixed-signal intertrated circuit applications in recent years. It has been proposed that higed permittivity(high-K)materials are used to replace conventional silicon oxide (K=～4) and nitride(K=～7) insulators. The application of high-K materials is confronted with great challenges.In this article, MIM capacitors with dielectric of HfO2and SiO2are studied.(1)Reactively sputtered HfO2and HfSixOy dielectrics have been investigated comparatively for metal-insulator-metal (MIM) capacitor applications. X-ray photoelectron spectroscopy analyses reveal the presence of Hf-O, Hf-O-Si and Si-O chemical bonds in the HfSixOy films as well as lots of oxygen vacancies. The relative concentrations of Hf-O-Si and Si-O bonds increase with an increment of the power applied to the Si target. Further, it is found that the quadratic voltage coefficient of MIM capacitor decreases with increasing the Si-O content in the HfSixOy dielectric in despite of a decrease in the resulting capacitance density. The HfSixOy dielectric MIM capacitors with a capacitance density of～8.4fF/μm2exhibit a quadratic voltage coefficient of1840ppm/V2at100KHz, which is much smaller than2750ppm/V2for the HfO2dielectric MIM capacitors with a density of～11.8fF/μm2.(2)Thin SiO2layers are deposited by plasma enhanced atomic layer deposition (PEALD) with Trisdimethylamino-silane (TDMAS:SiH(N(CH3)2)3) precursors. The purpose of this study is to evaluate the characteristics of the PEALD SiO2layers for metal-insulator-metal (MIM) capacitors for RF/analog circuit applications. The thic K ness of SiO2using PEALD process is controlled by the number of growth cycles under different temperature or O2pulse time. The films are analyzed by survey XPS spectra. The SiO2metal-insulator-metal (MIM) capacitor is made with the dielectric thic K ness as10nm. A relatively high capacitance density of4.2fF/μm2can be obtained while retaining the low lea K age current density of1×10-8A/cm2at1MV/cm. The quadratic voltage coefficients of capacitors are also deduced as low as-1450ppm/V2.(3)MIM capacitors with SiO2/HfO2/SiO2dielectric are manufactured by ALD technique.Vccs of MIM capacitors are decreased by adjusting the ratio of SiO2and HfO2in the dilectric films.The MIM capacitor with SiO2(1.5nm)/HfO2(9nm)/SiO2(1.5nm) dielectric exhibits a capacitance density of9.3fF/μm2at100KHz,Vcc of897ppm/V2and leaKage current of7.5×10-8A/cm2at3V. SiO2(1nm)/HfO2(10nm)/SiO2(1nm) MIM capacitor exhibits a capacitance density of10.2fF/um2at100KHz,Vcc of1210ppm/V2.