Fabrication of Silicon Nano-Devices with High Controllability beyond Lithography Limit

本研究的目的是开发一种高度可控的方法，用于制造超小的硅纳米器件超出光刻极限，而不使用精细光刻技术，如电子束光刻。我们提出了一种新的方法，利用各向异性蚀刻和多层氧化硅和氮化硅。采用选择性氧化和两次各向异性腐蚀的方法，在绝缘体上硅（SOI）衬底上成功地制备了精细的点接触沟道。制作的MOSFET具有良好的均匀性。漏极电流分布小于10%。此外，在低温下观察到由于单电子隧穿引起的库仑阻塞振荡。使用这种技术，单电子晶体管的集成也被执行。通过将单电子晶体管和具有硅纳米晶体浮点的存储器件组合，精确地控制单电子晶体管的特性，并且将库仑阻塞振荡的峰值位置调整到期望的位置。然后，将两个单电子晶体管集成以形成定向电流开关。制造工艺和器件控制对于单电子晶体管的实际集成是非常有效的。

The purpose of this study is to develop a highly controllable method for fabricating ultra-small silicon nano-devices beyond the lithography limit without using fine lithography techniques such as electron beam lithography. We have proposed a new method that makes use of anisotropic etching and multiple layers of silicon oxide and silicon nitride. Fine point contact channel was successfully fabricated by selective oxidation and two anisotropic etching steps on silicon-on-insulator (SOI) substrate. The fabricated MOSFET shows good uniformity. The distribution of drain current is less than 10%. Moreover, Coulomb blockade oscillations due to single electron tunneling are observed at low temperatures. Using this technique, the integration of single electron transistors is also performed. By combining the single electron transistor and a memory device with silicon nano-crystal floating dots, the characteristics of single electron transistors are precisely controlled and the peak positions of Coulomb blockade oscillations are adjusted to the desired positions. Then, two single electron transistors are integrated to form a directional current switch. The fabrication process and device control are very effective for the practical integration of single electron transistors.