Study On Mg Doped Chalcogenide Alloy For Phase Change Random Access Memory

With the rapid development of human society, the electronic product market’s need for storage rises with the day. Flash memory is the most popular nonvolatile memory,but after the 45 nm technology node, the device size will be difficult to shrink further, and its development has encountered many technical bottleneck. Therefore, the world’s major semiconductor companies are studying on new type semiconductor memory. Phase change memory has been considered as the most potential to become a new generation of non-volatile memory technology due to its fast reading speed, high frequency erasable, low power consumption, compatible with COMS technology. Aiming to some problems in the current phase change storage material, this thesis mainly study material and prepare several Mg doping phase change storage material, in order to find the most promising films as a storage medium. The main content of this thesis are as following:(1) Mg-ZnSb thin film was prepared, and its structure and electrical properties were mainly studied. The XPS test showed that the new Mg-Zn and Mg-Sb bond has already formed between the Mg and ZnSb. The research showed that doping Mg element, the crystallization temperature has increased to 278?C from 257?C. But the amorphous resistance, crystalline resistance and resistance ratio were constantly decreases.(2) Mg-Ge-Te film was prepared, and results showed that the Mg element destroyed the original Ge-Te bond, forming the new Mg-Ge and Mg-Te bonds. As Mg element doping, crystallization temperature, crystalline and amorphous resistance had a certain increase than the Ge2 Te film, and the resistance ratio also increased. In addition, Mg element also improved the transformation rate, which is increased with the Mg content. The crystallization temperature and resistance ratio of Mg14.2(Ge2Te)85.8 film is 236?C and 1.6?108.(3) Mg-Sb-Te film was prepared, and results shown that Mg has certain effect on the performance of Sb2 Te, Sb7Te3 and Sb4 Te. After the doping Mg element, the new Mg-Sb and Mg-Te bonds could help to develop the crystallization temperature(T) and the stability of the amorphous, also restained the crystallization process. The TEM showed that Mg element distributed around the grain and inhibited grain growth. Basing on laser induced platform test found that the Mg element could increase the phase change rate, and shorten the initiate crystallization time(Tc) and complete crystallization time(Ts). In addition, with the increasing of Sb content the Tc and Ts is also reduced. The T and Ts of Mg21.5(Sb2Te)78.5, Mg22.7(Sb7Te3)77.3, Mg19.8(Sb4Te)80.2 are 183?C, 176?C, 187?C and 55 ns, 55 ns, 20 ns. Considering all results above mentioned, the optimal Mg content is about 20%. Mg could develop the stability of Sb-Te base film, and make the film crystallization rate faster than GST(250ns), which is good to solve the problems on slow phase change rate and stability.