Synthesis And Capability Research Of The Ge(Ⅱ) Precursors For Phase-change Memory Storage Material

The high speed development of information technology remains a great challenge to the memory device. Phase change memory became the most potential next generation memory. At present,germanium material became a hotspot in the research on the GST(Ge-Sb-Tb) three element alloy phase-change memory material due to the largest arrangement of germanium atoms in the alloy during the process of phase transformation. But the relationship between the stable structure and excellent volatility still remain unexploried. Therefore,the main contents of this work including: the design and synthesis of Ge(II) compounds,their thermal properties,their film forming conditions, the establishment and the analyzation of the relationship between the structure and the property.In this paper,we designed new ligands to coordinate with Ge(II) and obtained new complexes with brand new representative structures by exploring the reaction conditions in order to study the effect of the different coordinations on the structure and the property. Furthermore,we screened the excellent precursors by studying the thermal properties following by the film forming. Finally, more research was combined with theoretical calculation. On the one hand, rationality of the structure of compounds was proved from the aspect of theory through the comparison of the data reported in the related literature, on the other hand, theories were summarized after researching on the impact of deep essence factor on the structure and thermal stability such as,structure of functional group,the electron density,steric effect and inductive effect factors. Details are as follows:1. In order to study the effect of the different coordination on the structure stability and the thermal property, different kinds of ligands were synthesized and coordinated toGe atom. The structures were characterized and influences on structure and thermal property were investigated such as, the coordination, the cyclization atomic number,the ring strain, the steric hinerance and the electronic effect. The result showed:firstly, it is proved that the rationality of the compound structure theory level through theoretical calculation comparison with the literature data reported crystal structure data, and through the combined analysis of NMR data and elemental analysis data,further proof that the design and selection of ligands are available with divalent germanium were coordinated and formed by outer ten four electron with a complexes can exist stably. Secondly, through the compound thermal gravimetric analysis comparison of data analysis, we find that the pyrazolyl divalent germanium compounds had secondary weightlessness in the heating process and can not be directly filmed on the silicon due to its unique three membered ring structure ring tension is large. The other compounds were different in weight loss, but most of the compounds were stable during heating. Thus we can get conclusion: ring or not and number of ring atoms have a significant influence on the thermal stability of the compound, but effects on volatile temperature is not obvious.2. In order to study the effect of the number, steric hinerance and the electronic effect of the substiutents on the structure stability and the thermal property, the property of the same series of complexes were compared by changing the substiuents. Combined with the result of the research on the coordination and the calculation, the result showed: on the one hand, the functional groups have an effect on the thermal stability of the compound. Functional groups can influence the stability of compound through changes in the steric hinerance and electronic effects, but functional groups on the compounds less influence the thermal stability than coordination modes. On the other hand, the effect of functional groups on the evaporation temperature and evaporation rate is very significant. The weight loss temperature of the compound was affected by the adjustment of the functional groups, and the volatile property of the compound was affected by the structural characteristics of the symmetry and steric hindrance. Meanwhile, the experimental results showed that the simple functional groups can only reduce the initial weight loss temperature, but too simple of ligands can cause the compound in the process of heating decomposition. The precursor can be obtained only by simplifying the functional groups on the basis of structural stability. Based on the idea, a secondary amine divalent germanium compound has been synthesized. It has excellent volatility properties and film-forming properties, is a potential precursor for phase-change storage materials. 3. We researched the thermal properties for screening the excellent precursors and explored the best film forming conditions. Then the films were deposited by using CVD technology and the lab-build equipment. The experiments exhibited that the structure of substituent can adjust the volatile performance. Above all, these experimental conditions data as well as the exploration and summary of the pretesting on phase change memory materials had very important directive significance to the processing technology and even the integration of III-IV compounds and Si materials in the field of microelectronic materials.