Fundamental Study on the Etching Mechanics of Metal-Assisted Chemical Etching of Silicon for 2D and 3D Nanomanufacturing Applications

这项拟议的研究旨在了解金属辅助化学刻蚀硅(MACE)中催化剂运动的基本机制。MACE是一种新的、新颖的方法，可以刻蚀复杂的2D和3D形状，如亚表面摆线和3D螺旋结构，同时保持1 nm的严格特征分辨率，即使纵横比为50：1。这些能力是由于这样一个事实，即定义刻蚀轮廓的金属催化剂在硅被催化剂上的电化学反应刻蚀时进入硅，导致刻蚀轮廓在整个刻蚀长度内被紧密地保持，并且能够通过控制催化剂的运动来刻蚀3D结构。虽然MACE的化学计量化学已经被合理地建立，但涉及粒子运动的基本动力学和力仍然是未知的和未被研究的。这项拟议的研究将考察腐蚀剂组成、催化剂形状、催化剂组成和外场如何影响MACE的动力学和作用力，以确定刻蚀速度、分辨率、形态和方向。此外，还将建立电场、力、催化剂运动和腐蚀形貌的分析和计算模型。将考察新催化剂材料的动力学和形态效应，并将其纳入模型。这项研究将使我们更好地理解MACE的动力学和催化剂颗粒形状如何相互作用来创建3D纳米结构，最终目标是提供对刻蚀方向的精确控制。过去十年对纳米材料和纳米技术的浓厚兴趣归因于工业对更低成本、更复杂设备的渴望，以及纳米技术为科学家提供了在近原子水平上探索自然基本性质的机会。为了追求这些目标，世界各地的研究人员努力完善现有技术，同时开发新的纳米制造方法；然而，尚不存在能够以低成本制造具有高纵横比、光滑的壁的复杂的2D和3D纳米尺寸特征的技术。目前的纳米制造方法面临着两个重要的局限性。首先，3D几何图形即使不是不可能制造，也是困难的，需要多个光刻步骤，这些步骤既昂贵又不能很好地适应工业级制造要求。其次，随着特征尺寸缩小到纳米领域，在大深度和大高度上准确保持这些特征变得越来越困难。以可承受的成本和高精度制造这些结构的能力对许多现有和新兴的技术至关重要，例如用于高频带通信设备的超材料，用于低成本检测癌症和其他疾病的先进芯片上生物设备的纳米流体，用于快速、低成本制造的纳米压印光刻等等。世界各地的科学家都在寻求使用纳米材料来减少人类活动对环境的影响，拟议中的研究将有助于实现这一目标所需的技术。

The proposed research seeks to understand the fundamental mechanisms involved in catalyst motion in Metal-assisted Chemical Etching of Silicon(MaCE). MaCE is a new, novel method to etch complex 2D and 3D shapes such as subsurface cycloids and 3D spiraling structures while maintaining tight feature resolutions on the order of 1 nm even with aspect ratios 50:1. These capabilities are enabled by the fact that the metal catalyst that defines the etching profile travels into the silicon as the silicon is etched by a galvanic reaction across the catalyst, resulting in etching profile is tightly maintained over the entire etch length along with the ability to etch 3D structures by controlling catalyst motion.While the stoichiometric chemistry of MaCE has been reasonably established, the fundamental kinetics and forces involved in particle motion have remain unknown and unstudied. The proposed research will examine how etchant composition, catalyst shape, catalyst composition and external fields affect the kinetics and forces of MaCE to determine etching rate, resolution, morphology and direction. Also, analytical and computational models of the electric fields, forces, catalyst motion and etching morphology will be developed. The kinetic and morphological effects of new catalyst materials will be examined and incorporated into the models. This research will provide a greater understanding on how the kinetics of MaCE along with the catalyst particleshape interact to create 3D nanostructures with the ultimate goal of providing precise control over etching direction.The considerable interest in nanomaterials and nanotechnology over the last decade is attributed to both the desire by industry for lower cost, more sophisticated devices and the opportunity that nano-technology presents for scientists to explore the fundamental properties of nature at near atomic levels. In pursuit of these goals, researchers around the world have worked to both prefect existing technologies and also develop new nano-fabrication methods; however, no technique exists that is capable of producing complex, 2D and 3D nano-sized features with high aspect ratios, smooth walls, and at low cost. Current nanofabrication methods face two important limitations. First, 3D geometry is difficult if not impossible to fabricate requiring multiple lithography steps that are both expensive and do not scale well to industrial level fabrication requirements. Second, as feature sizes shrink into the nano-domain, it becomes increasingly difficult to accurately maintain those features over large depths and heights. The ability to produce these structures affordably and with high precision is critically important to a number of existing and emerging technologies such as metamaterials for high-band with communication devices, nano-fluidics for advanced bio-on-a-chip devices to detect cancer and other disease at low cost, nano-imprint lithography for rapid, low cost fabrication, and more.The proposed research seeks to develop the fundamental understand of MaCE as a new method to create 2D and 3D nanostructures with high feature fidelity even at high aspect ratios and a low cost. Scientists around the world are looking to use nanomaterials to reduce the environmental impact of human activities and the proposed research will help enable the technology needed to achieve this goal.