New Top-Down Approach for Fabricating Si-Based Nanostructures

Abstract

We propose a novel CMOS-compatible top-down nanofabrication technique of highly-ordered Si-based nanostructures using a single amorphous silicon (α-Si) material. The pattern of α-Si layer is precisely transferred into the underlying SiO2 material. Then, various well-controlled SiO2nanostructures fabricated by this approach can be used as nanotemplates to transfer into the underlying substrate materials such as silicon, germanium, transistor gate or other semiconductor materials to fabricate specifically required nanostructures by RIE processes. To the best of our knowledge,it is the first time for α-Si film used as an etch mask to fabricate Si-based nanostructures including nanoline, nanotrench, nanohole and nanofin arrays. It is observed that the α-Si mask can significantly reduce the pattern edge roughness and achieve highly uniform and smooth sidewalls. This behavior may be attributed to presence of high concentration of dangling bonds in α-Si material surface. By controlling the process condition, it is possible to achieve desired vertical etched profiles with precisely controlled sizes. In addition, our results indicate that silicon nanostructures can be further trimmed to smaller than 10nm by combing with assisted post-treatment methods such as H2anneal process. For bulk Finfet devices, the size of top CD of silicon nanofins around 5nm have been easily achieved via this method. Our results fully demonstrate a great potential of α-Si material in the fabrication of a large number of Si-based nanostructures. Moreover, the novel top-down approach is a potentially universal method that is fully compatible with the current existing Si-based CMOS technologies. It will be expected a new emerging and disruptive technology with low process complexity and high throughput compared with existing silicon fabrication techniques, and it offers a greater flexibility for the fabrication of various nanoelectronics, biosensors and optoelectronic devices in a cost-effective and efficient way. Figure 1