Sn-doped Ge2Sb2Te5 thin films deposited on Si（100）/SiO2 substrates by rf magnetron sputtering are investigated by a differential scanning calorimeter, x-ray diffraction and sheet resistance measurement. The crystall...Sn-doped Ge2Sb2Te5 thin films deposited on Si（100）/SiO2 substrates by rf magnetron sputtering are investigated by a differential scanning calorimeter, x-ray diffraction and sheet resistance measurement. The crystallization temperatures of the 3.58 at.%, 6.92 at.% and 10.04 at.% Sn-doped Ge2Sb2Te5 thin films have decreases of 5.3, 6.1 and 0.9℃, respectively, which is beneficial to reduce the switching current for the amorphous-to-crystalline phase transition. Due to Sn-doping, the sheet resistance of crystalline Ge2Sb2Te5 thin films increases about 2-10 times, which may be useful to reduce the switching current for the amorphous-to-crystalline phase change. In addition, an obvious decreasing dispersibility for the sheet resistance of Sn-doped Ge2Sb2Te5 thin films in the crystalline state has been observed, which can play an important role in minimizing resistance difference for the phase-change memory cell element arrays.展开更多
A damascene structure of phase change memory （PCM） is fabricated successfully with the chemical mechanical polishing （CMP） method, and the CMP of Ge2Sb2Te5 （GST） and Ti films is investigated. The polished surfac...A damascene structure of phase change memory （PCM） is fabricated successfully with the chemical mechanical polishing （CMP） method, and the CMP of Ge2Sb2Te5 （GST） and Ti films is investigated. The polished surface of wafer is analysed by scanning electron microscopy （SEM） and an energy dispersive spectrometer （EDS）. The measurements show that the damascene device structure of phase change memory is achieved by the CMP process. After the top electrode is deposited, dc sweeping test on PCM reveals that the phase change can be observed. The threshold current of array cells varies between 0.90mA and 1.15mA.展开更多
In order to improve nano-scale phase change memory performance, a super-clean interface should be obtained after chemical mechanical polishing （CMP） of Ge2Sb2Te5 phase change films. We use reactive ion etching （RIE...In order to improve nano-scale phase change memory performance, a super-clean interface should be obtained after chemical mechanical polishing （CMP） of Ge2Sb2Te5 phase change films. We use reactive ion etching （RIE） as the cleaning method. The cleaning effect is analysed by scanning electron microscopy and an energy dispersive spectrometer. The results show that particle residue on the surface has been removed. Meanwhile, Ge2Sb2Te5 material stoichiometric content ratios are unchanged. After the top electrode is deposited, currentvoltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1 mA to 0.025 mA. Furthermore, we analyse the RIE cleaning principle and compare it with the ultrasonic method.展开更多
In this paper, a two dimensional Voronoi cell element, formulated with creep, thermal and plastic strain, is applied for the numerical simulation of thermo-mechanical fatigue behavior for particulate reinforced compos...In this paper, a two dimensional Voronoi cell element, formulated with creep, thermal and plastic strain, is applied for the numerical simulation of thermo-mechanical fatigue behavior for particulate reinforced composites. The relation between mechanical fatigue phases and thermal fatigue phases influences the thermo-mechanical fatigue behavior and cyclic creep damage. The topological features of micro-structure in particulate reinforced composites, such as the orientation, depth-width ratio, distribution and volume fraction of inclusions, have a great influence on thermo-mechanical behavior. Some related conclusions are obtained by examples of numerical simulation.展开更多
为获得细胞膜受冲击破损的实际应力应变值。应用原子力显微镜(atomic force microscope,AFM)对Hela细胞进行破膜实验,得到细胞几何参数和加载过程的力-位移曲线。基于实验所得表面形貌与材料参数建立细胞破损有限元模型,并使用ABAQUS进...为获得细胞膜受冲击破损的实际应力应变值。应用原子力显微镜(atomic force microscope,AFM)对Hela细胞进行破膜实验,得到细胞几何参数和加载过程的力-位移曲线。基于实验所得表面形貌与材料参数建立细胞破损有限元模型,并使用ABAQUS进行分析。当针尖位移达到2.35μm时,实验所得破膜力为38.7 nN,模拟所得破膜力为39.3 nN,两者较为吻合,验证了模型的合理性和正确性。通过模拟获得细胞膜被穿破时,应力为24.3 kPa,塑性应变为0.23。本研究基于实验建立的细胞破损有限元模型,为模拟细胞的失效与破损过程提供了方法和参考。展开更多
文摘Sn-doped Ge2Sb2Te5 thin films deposited on Si（100）/SiO2 substrates by rf magnetron sputtering are investigated by a differential scanning calorimeter, x-ray diffraction and sheet resistance measurement. The crystallization temperatures of the 3.58 at.%, 6.92 at.% and 10.04 at.% Sn-doped Ge2Sb2Te5 thin films have decreases of 5.3, 6.1 and 0.9℃, respectively, which is beneficial to reduce the switching current for the amorphous-to-crystalline phase transition. Due to Sn-doping, the sheet resistance of crystalline Ge2Sb2Te5 thin films increases about 2-10 times, which may be useful to reduce the switching current for the amorphous-to-crystalline phase change. In addition, an obvious decreasing dispersibility for the sheet resistance of Sn-doped Ge2Sb2Te5 thin films in the crystalline state has been observed, which can play an important role in minimizing resistance difference for the phase-change memory cell element arrays.
文摘A damascene structure of phase change memory （PCM） is fabricated successfully with the chemical mechanical polishing （CMP） method, and the CMP of Ge2Sb2Te5 （GST） and Ti films is investigated. The polished surface of wafer is analysed by scanning electron microscopy （SEM） and an energy dispersive spectrometer （EDS）. The measurements show that the damascene device structure of phase change memory is achieved by the CMP process. After the top electrode is deposited, dc sweeping test on PCM reveals that the phase change can be observed. The threshold current of array cells varies between 0.90mA and 1.15mA.
基金Supported by the National Basic Research Programme of China under Grant Nos 2007CB935400 and 2006CB302700, the National High-Tech R＆D Programme of China under Grant No 2006AA03Z360, the Science and Technology Council of Shanghai under Grant Nos 06QA14060, 06XD14025, 0652nm003, 06DZ22017, 0752nm013 and 07QA14065, and the National Natural Science Foundation of China under Grant Nos 60706024, 60776058.
文摘In order to improve nano-scale phase change memory performance, a super-clean interface should be obtained after chemical mechanical polishing （CMP） of Ge2Sb2Te5 phase change films. We use reactive ion etching （RIE） as the cleaning method. The cleaning effect is analysed by scanning electron microscopy and an energy dispersive spectrometer. The results show that particle residue on the surface has been removed. Meanwhile, Ge2Sb2Te5 material stoichiometric content ratios are unchanged. After the top electrode is deposited, currentvoltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1 mA to 0.025 mA. Furthermore, we analyse the RIE cleaning principle and compare it with the ultrasonic method.
基金The project supported by the Special Funds for the National Major Fundamental Research Projects(2004CB619304)the National Natural Science Foundation of China(10276020 and 50371042)the Key Grant Project of Chinese Ministry of Education(0306)
文摘In this paper, a two dimensional Voronoi cell element, formulated with creep, thermal and plastic strain, is applied for the numerical simulation of thermo-mechanical fatigue behavior for particulate reinforced composites. The relation between mechanical fatigue phases and thermal fatigue phases influences the thermo-mechanical fatigue behavior and cyclic creep damage. The topological features of micro-structure in particulate reinforced composites, such as the orientation, depth-width ratio, distribution and volume fraction of inclusions, have a great influence on thermo-mechanical behavior. Some related conclusions are obtained by examples of numerical simulation.
