A Microfabrication Compatible Method to Fabricate Silicon Nanotubes for Nanoprobe Applications

自上而下的微制造是制造计算机芯片和微机电系统传感芯片的过程，是当前半导体和传感器行业的基础。然而，各种纳米级结构和材料的出现可以显著提高这些芯片的性能。然而，由于这些纳米级材料和结构的制造工艺与标准微加工工艺不兼容，在这些芯片上无缝集成这些纳米级材料和结构存在许多挑战。该奖项支持开发室温微加工工艺以制造硅纳米管的基础研究。新工艺允许在同一芯片上制造具有其他功能元件或电子元件的硅纳米管，而不会产生热损伤。由多种材料（如半导体、化合物半导体和金属）制成的纳米管和纳米管功能器件在医疗保健、生物医学、能源、航空航天和化学工业中具有巨大的应用潜力。因此，这项研究的成果有利于美国的经济和社会。这项研究涉及多个学科，包括制造、计算、神经科学和材料科学，从而有助于扩大妇女和代表性不足的少数民族学生参与研究，并对工程和科学教育产生积极影响。该项目旨在开发一种可扩展的、环境温度的、自上而下的工艺来制造单晶硅纳米管。硅纳米管的制造是通过一系列集成电路（IC）兼容的微加工工艺来实现的。具体地说，聚苯乙烯纳米球（NS）珠首先在硅片上自组装成紧密堆积的单层。然后通过氧等离子体反应离子蚀刻（RIE）来缩小这些NS珠的尺寸。以NS珠为掩膜，采用电感耦合等离子体（ICP）博世法制备了硅纳米管。本研究填补了如何在芯片上以可控方式实现单纳米管或纳米管阵列的大规模集成和排列的技术知识空白。研究小组计划进行尖锐的界面相场纳米尺度建模，以基本理解和控制制造坚固硅纳米管的加工参数的公差范围。此外，研究小组计划开发基于硅纳米管的膜片钳纳米探针，用于神经元和细胞的刺激和记录。具体来说，基于硅纳米管的膜片钳纳米探针阵列嵌入微尺度细胞培养室中，用于记录已分化为少突胶质细胞、星形胶质细胞或神经元的成年海马祖细胞培养中的电生理活动，以及绘制神经元之间的多个单个突触连接。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Top-down micromanufacturing is the process for fabricating computer chips and microelectromechanical system sensing chips and is the basis for the current semiconductor and sensor industries. However, the emergence of various nanoscale structures and materials can significantly improve the performance of these chips. However, numerous challenges exist to integrate these nanoscale materials and structures on these chips seamlessly due to incompatibility of their fabrication process with standard microfabrication processes. This award supports fundamental research to develop a room-temperature microfabrication process to fabricate silicon nanotubes. The new process allows the manufacturing of silicon nanotubes with other functional elements or electronics on the same chip without thermal damage. Nanotubes and nanotube-enabled functional devices fabricated from a wide variety of materials such as semiconductors, compound semiconductors, and metals have great potential for applications in healthcare, biomedical, energy, aerospace, and chemical industries. Hence, the outcomes from this research benefits the U.S. economy and society. This research involves several disciplines including manufacturing, computation, neuroscience and material science, thereby helping broaden participation of women and underrepresented minority students in research and having a positive impact on engineering and science education. The project seeks to develop a scalable, ambient temperature, top-down process to fabricate single crystal silicon nanotubes. The fabrication of the silicon nanotubes is realized by simply using a series of integrated circuit (IC)-compatible microfabrication processes. Specifically, polystyrene nanosphere (NS) beads are first self-assembled into a close-packed monolayer on a silicon wafer. These NS beads are then tailored by oxygen plasma reactive ion etching (RIE) to shrink their size. Using the NS beads as the mask, the silicon nanotubes are fabricated by inductively coupled plasma (ICP) Bosch process. This research fills the technical knowledge gap on how to realize the large-scale integration and arrangement of a single nanotube or an array of nanotubes in a controlled manner on a chip. The research team plans to perform sharp interface phase-field nanoscale modeling for fundamental understanding and control of the tolerance range of the processing parameters for fabricating robust silicon nanotubes. In addition, the research team plans to develop silicon nanotube-based patch-clamp nanoprobes for neuronal and cellular stimulation and recordings. Specifically, arrays of silicon nanotube-based patch-clamp nanoprobes embedded within microscale cell culture chambers are developed for recording electrophysiological activity in cultures of adult hippocampal progenitor cells that have differentiated into oligodendrocyte, astrocytes or neurons as well as mapping multiple individual synaptic connections between neurons.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.