Study On Doping Modification And Reversible Phase Transition Of Sb - Te Based Thin Films

Phase change materials as an information storage medium for rewritable phase change memory and phase-change optical disk, due to its advantages on high speed, low power consumption and high density, has been draw more and more attention in the next-generation rewritable nonvolatile memories. Ge2Sb₂Te5（GST） is one of the most widely used phase change materials at present, but its poor thermal stability limits its further application. Sb-Te binary alloy is considered as another important phase-change material system which has a faster crystallization speed than that of GST, due to its growth-dominated crystallization mechanism. However, the poor amorphous phase stability and overlarge grain size of Sb–Te material hinder its application. To improve the thermal stability of Sb-Te We aimed to study the structure of Sb-Te in GST, and to study the doping modification, which has achieved the aim of fast phase transformation and good thermal stability. Through the research, the main results of this paper are presented as fllowing:1. The rearch of Sb₂Te doping material. The doping of SiX（X is O, N, C） effectively inhibit the crystallization of Sb₂Te material, and the smaller grain size greatly improves the thermal stability. At the same time, the device based on SiX-Sb₂Te materials can operate SET/RESET under 10 ns, while keep the difference between high and low resistance close to two orders of magnitude. At the same time, the number of cycles can reach more than 104, having broad prospects in the automotive electronics field.1) The crystallization temperature of SiO₂- Sb₂Te can reach more than 200 ℃ and 10-year data rention could rench about 130 ℃, greatly improving the Sb₂Te material on the thermal stability of the amorphous. The device based on Sb₂Te-SiO₂ materials, SET/RESET operating could up to 10 ns, indicating that SiO₂-Sb₂Te material still have the characteristics of fast phase transformation of Sb₂Te materials.2) The crystallization temperature of SiNx-Sb₂Te material can reach above 220 ℃, 10-yeat data rention is about 140 ℃. At the same time, the SET/RESET operation of the deveice based on the SiNx- Sb₂Te material can be as short as 8 ns, indicating fast phase change characteristics.3) The crystallization temperature of SiC-Sb₂Te material can reach above 250℃, 10- year data rention is about 150 ℃. The reversible switching of thePCM based the Sb₂Te-SiC material up to forty thousand times.2. W_xSb₃Te phase change material with high speed and high thermal stability is proposed. The incorporation of W instead of Sb atom or Te atom in the Sb3 Te material, inhibiting the diffusion of atoms, refineing the grain size, improving the optical band gap width. With the increasing of W content, the crystallization temperature of the material and the temperature of the 10-year data retention are all increased, showing a better thermal stability. After adding W, the adhesion property of the material and the electrode material can be improved, which is beneficial to improve the reliability of the device. The device can still operate under the voltage pulse of 10 ns, and the SET-RESET can be operated stably.