NER: Silicide Quantum Dots for Nanoelectronics

本提案是对纳米科学和工程计划NSF 01-157的响应而收到的，属于NER类别。该提案的重点是纳米级硅化物量子点的制备。硅化物点在制造量子细胞自动机和其他量子点器件方面具有潜在的应用价值。量子细胞自动机是量子点的集合，可以执行基本的信息处理功能，如互连、数字逻辑和存储器。尤其是探索硅化物量子点的一个主要动机是，它们将与硅器件兼容，而硅器件可能仍将用作纳米电子与外部世界之间的接口。这项研究将探索新的纳米级制造工艺，并将加深对纳米级表面化学反应和相变的理解。我们希望展示原位光刻、金属选择性沉积、硅化物形成和外延层过度生长的集成。具体地说，光刻将通过用电子束曝光薄的二氧化硅层来执行，从而增强从暴露区域的氧化物的热解吸。随后，量子点将通过化学气相沉积和反应形成金属硅化物。一种特别吸引人的方法是从有机金属源中选择性地沉积形成硅化物的金属，尽管也可以探索其他方法。这项研究将使用最近建造的设备进行，该设备将电子束图案化与量子点的沉积和表征相结合。所有的工艺步骤，包括量子点的外延过度生长，都可以在不将衬底暴露在大气中的情况下进行。工作中使用的表征工具包括反射高能电子衍射、热解吸质谱和原子力显微镜。在这个为期一年的探索性计划中，我们希望制造出尺寸在20-40 nm范围内的图案化硅化物量子点。我们还将获得对选择性生长的更好的科学理解，这将在纳米级器件的制造中广泛使用。

This proposal was received in response to the Nanoscale Science and Engineering Initiative, Program Solicitation NSF 01-157, in the NER category. The proposal focuses on the fabrication of nanoscale silicide quantum dots. Silicide dots are potentially useful for fabrication of quantum cellular automata and other quantum dot devices. Quantum cellular automata are assemblies of quantum dots which can perform the basic information-processing functions of interconnect, digital logic, and memory. A major motivation for the exploration of silicide quantum dots in particular is the fact that they will be compatible with silicon devices which will probably remain useful as an interface between nanoelectronics and the outside world. This research will explore novel nanoscale fabrication processes and will develop improved understanding of surface chemical reactions and phase transitions on the nanoscale. We wish to demonstrate the integration of in situ lithography, selective deposition of metals, silicide formation, and epitaxial layer overgrowth. In particular, lithography will be performed by exposing thin silicon dioxide layers with an electron beam, thereby enhancing thermal desorption of oxide from the exposed regions. Subsequently the quantum dots will be formed by chemical vapor deposition and reaction to form a metallic silicide. One particularly attractive approach is selective deposition of the silicide-forming metal from an organometallic source, although other approaches may also be explored. This research will be performed using a recently constructed apparatus which combines electron beam patterning with the deposition and characterization of quantum dots. All process steps, including epitaxial overgrowth of the quantum dots, can be performed without exposing the substrates to atmosphere. Characterization tools to be used in the work include reflection high energy electron diffraction, thermal desorption mass spectrometry, and atomic force microscopy. Within this one-year exploratory program, we expect to fabricate patterned silicide quantum dots in the 20-40 nm size range. We will also obtain improved scientific understanding of selective growth which will be broadly useful in the fabrication of nanoscale devices.