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Fabrication of Nanocrystal Memories by Position Controlled Deposition of Ge Nanocrystals

通过位置控制沉积 Ge 纳米晶体制造纳米晶体存储器

基本信息

批准号：
14350183
负责人：
NOZAKI Shinji
金额：
$ 9.54万
依托单位：
The University of Electro-Ccmmunications
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

In this research project, we made an attempt to make a nanocrystal memory using a silicon substrate on which Ge nanocrystalls are deposited with a good control of the positioning and size. Dr. Berbezier at CRMC2, Marseille, France provided the Si substrates with Ge nanocrystals deposited by MBE, and we made MOS capacitors by embedding Ge nanocrsytals in SiO_2. The most important but difficult part of the project is to deposit Ge nanocrstals with a good control of positioning and size. Dr. Berbezier and her group members developed a technique to grow the Ge nanocrstals on the FIB-patterned Si substrates. In this technique, the Ga is implanted in the Si substrates by focused ion beam (FIB) and farms the defective area locally. It was found the Ge selectively grew on the damaged area in the MBE growth of Ge. Using this selective epitaxy of Ge, Ge nanocrystals can be arranged. With the optimized growth condition, Dr. Berbezier successfully achieved an array of Ge nanocrystals on Si. Howeve … More r, the array was not one monolayer, and some Ge nanocrystals were stacked. Such a sample did not show a significant flatband voltage shift by injecting electrons in Ge nanocrystals.Nozaki and his group proposed a technique to form a high-density of Ge nanocrystals in a monolayer. In this technique, the Ge nanocrystals were deposited on the tunnel oxide by the gas evaporation with a supersonic jet nozzle. Using this deposition method, the Ge nanocrystals with a good uniformity in the size were obtained. They are, however, stacked. The Ge nanocrystals were annealed to remove the extra naocrystals on the monolayer. Because of strength of bonding between Ge nanocrystals and SiO_2, one monolayer of Ge nanocrystals remained without losing any nanocrystals on SiO_2 after complete removal of the extra nanocrystals. Then, the Ge nanocrystals were exposed to UV light for photo-oxidation, which electrically isolates the Ge nanocrystals by oxidizing the Ge nanocrystals. After depositing the control oxide on the Ge nanocrystals, the MOS capacitors with the Ge nanocrystals as a floating gate were fabricated. The C-V showed the hysteresis to confirm the electron injection in the nanocrystals. Although the gate electrode with the Ge nanocrystals proved to be useful in the nanocrystal memories, the further improvement of charge retention is required for practical application. Less

在这个研究项目中，我们尝试使用硅基底制造纳米晶体存储器，在硅基底上沉积Ge纳米晶体，并很好地控制位置和尺寸。法国马赛CRMC2的Berbezier博士提供了采用MBE沉积的Ge纳米晶体的Si衬底，我们通过将Ge纳米晶体嵌入SiO_2中制作了MOS电容器。该项目最重要但最困难的部分是在良好控制位置和尺寸的情况下沉积Ge纳米晶体。 Berbezier 博士和她的小组成员开发了一种在 FIB 图案化的 Si 基板上生长 Ge 纳米晶体的技术。在该技术中，通过聚焦离子束（FIB）将Ga注入到Si衬底中，并局部形成缺陷区域。在Ge的MBE生长中发现Ge选择性地生长在受损区域。利用Ge的这种选择性外延，可以排列Ge纳米晶体。通过优化的生长条件，Berbezier 博士成功地在 Si 上获得了一系列 Ge 纳米晶体。然而，这个阵列并不是单层的，而是一些Ge纳米晶体堆叠在一起。通过在Ge纳米晶体中注入电子，这样的样品没有表现出显着的平带电压偏移。Nozaki和他的小组提出了一种在单层中形成高密度Ge纳米晶体的技术。在该技术中，Ge纳米晶体通过超音速喷嘴的气体蒸发沉积在隧道氧化物上。采用该沉积方法，获得了尺寸均匀性良好的Ge纳米晶。然而，它们是堆叠在一起的。对Ge纳米晶体进行退火以去除单层上多余的纳米晶体。由于Ge纳米晶与SiO_2之间的结合力强，在完全去除多余的纳米晶后，SiO_2上仅保留一层单层Ge纳米晶，而没有失去任何纳米晶。然后，将Ge纳米晶体暴露在紫外光下进行光氧化，通过氧化Ge纳米晶体来电隔离Ge纳米晶体。在Ge纳米晶上沉积控制氧化物后，制备了以Ge纳米晶作为浮栅的MOS电容器。 C-V 显示出滞后现象，以确认纳米晶体中的电子注入。尽管具有Ge纳米晶体的栅电极被证明在纳米晶体存储器中是有用的，但实际应用需要进一步提高电荷保持能力。较少的