| Ferroelectric memory is a kind of nonvolatile memory that uses ferroelectric material as a data carrier.Because of its good storage performance,it has attracted much attention in medical treatment,aerospace,and other fields.However,the existing perovskite-type ferroelectric thin film materials have poor micro scalability and are not compatible with CMOS technology,which makes the integration process of ferroelectric memory complex and the storage capacity is small,which limits the large-scale application of ferroelectric memory.Fluorite hafnium oxide based ferroelectric thin film is highly compatible with CMOS process new ferroelectric material,can be made into high speed,low power consumption of non-volatile ferroelectric memory,and with high dielectric constant,the advantages of the wide bandgap in ferroelectric random access memory,iron in the electric field effect transistor has very good application prospect.Recent studies have shown that significant ferroelectric properties can be observed when HfO2nanofilms are doped with an appropriate amount of elements(Al,Y,La,etc.).As a new environment-friendly ferroelectric material,the study of HfO2based thin film's excellent ferroelectric properties will play a great role in promoting the further development of memory.Therefore,in this paper,the effects of doping elements on the properties of hafnium-based ferroelectric thin films were studied by optimizing the preparation process of the films and exploring the effects of doping elements on the properties of the films.It mainly includes the following aspects:(1)The preparation process of the film was optimized,and the relevant factors affecting the experiment were summarized.If the precursor is prepared in the process,the indoor temperature should be maintained at about 30?,and the humidity should be between 20%and 30%.During the annealing process,the films were firstly heated up slowly to prevent cracking,and the impurities were gradually removed.Then,the crystal phase was stabilized by rapid annealing,and the uniform and compact HfO2based ferroelectric films were prepared.(2)The Pt/Y:HfO2ferroelectric thin films/SiO2/Si ferroelectric capacitors were prepared by the sol-gel method.The electrical properties and microstructure characteristics of Y:HfO2ferroelectric thin films were analyzed in detail under different Y:HfO2concentrations,annealing conditions,and thicknesses.The results show that at the doping concentration of 5 mol%,the annealing temperature of 850?,the one-layer thin film has good properties(2Pr=66.81?C/cm2,@11 V,leakage current density of 1×10-8A/cm2,@10 V,and dielectric turnover capacitance of 526p F),and the crystal structure is the ferroelectric normalized phase.The Pt/La:HfO2ferroelectric thin films/SiO2/Si ferroelectric capacitors were prepared by the sol-gel method.The electrical properties and microstructure characteristics of La:HfO2ferroelectric thin films were analyzed in detail under different concentrations and annealing conditions of La:HfO2.The results show that all the samples are ferroelectric orthogonalization phase,which indicates that lanthanum as a dopant has a wider doping range.We obtained a better ferroelectric property(2Pr=49.82?C/cm2,@19 V),a leakage current density of 1×10-7A/cm2,@10 V,and a dielectric turnover capacitance of 374 p F in the sample with a doping concentration of 6 mol%and annealing temperature of 850?. |
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