Fabrication And Characteristics Study Of HfO₂ -based High-k Thin Films

With the rapid development of IC (integrated circuit), the size of MOSFET which is an crucial device of microelectronics, is continuously reducing, as a result, many problems appears, the most conspicuous of which is that, when the equivalent oxide thickness is less than 1.5nm, the traditional gate dielectric SiO2 approach the its threshold thickness, Because of quanta tunneling effect, the leakage current will rise exponentially, which will threat the stability and reliability of the device and restricts the IC development. In order to solve this problem, we need to seek new high-k dielectrics to replace SiO2, and the new material should behave favorable thermal stability, wider energy gap and can resolve compatibility issues with traditional IC technology. HfO2 have been widely investigated as the most promising candidates for its excellent performance.The films are deposited by means of direct current (DC) reactive magnetron sputtering and pulsed laser deposition (PLD). Influence of preparation technology on the microstructures, stoichiometry and electricity property analysis of the films were studied with X-ray diffraction(XRD), atomic force microscopy(AFM) and I~V curve and C~V curve,respectively.The research contents of this paper are as follows:1. In different O2/Ar ratio and substrate temperatures HfO2 films were grown, found its crystal form is monoclinic or orthorhombic type, while the metal film prepared by post-annealed monoclinic HfO2 is monoclinic type; Leakage current mechanism is composed of F-P emission and Schottky emission codecision.After the Hafnium film at 500℃annealed HfO2 films prepared has the smallest leakage current,at -1V bias, the leakage current of 1.26×10-7A/cm2;HfO2 films prepared in different O2/Ar ratio have a relative dielectric constant 20.01~25.26. The relative dielectric constant of HfO2 thin films prepared in different substrate temperatures is 21.15~25.47.Metal film post-annealed HfO2 films prepared its relative dielectric conatant 17.76~23.30.2. Hf1-xZrxO film, Hf1-xAlxO film and Hf1-xSixO film prepared by magnetron sputtering and pulsed laser deposition.The study found that,Al-doped films crystal during 900℃,Si-doped films prepared by 500℃~900℃annealed is amorphous film,Zr doping on the films does not affect crystallization temperature.Film leakage current emission mechanism is F-P emission and Schottky emission; Hf1-xAlxO film have the smallest leakage current, at -1V bias,that is 1.99×10-8A/cm2.