Shalom J. Wind - US grants

Proposal no: 508319
Title: NER/SNB: High-frequency, three-dimensional integrated CNFET/CMOS technology
Inst: Columbia University
PI: Ken Shepard


Carbon nano-tube field-effect transistors (CNFET) have emerged as a potential alternative field-effect technology to conventional deep-submicron silicon transistors. While operating under physical principles similar to complementary metal-oxide semiconductor (CMOS) silicon field-effect transistors, these devices offer several possible advantages in circuits including reduced short-channel effects, potential molecular-level control to reduce variability, and a hybrid three-dimensional integration in which active devices (CMOS on the bottom and CNFET on the top) will sandwich the metal interconnect layers. For any of these potential advantages to be realized, these devices must coexist with silicon CMOS FETs and must be able to leverage the existing investment in CMOS process technology. By combining CMOS-compatible CNFET fabrication with comprehensive circuit-focused device characterization, the PIs seek to further explore the potential advantage of CNFETs for real microelectronics applications while pursuing the development of viable circuits that combine CNFET transistors with conventional deep submicron CMOS technology.

This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 04-043, category NIRT.

This Nanoscale Interdisciplinary Research Team (NIRT) project will create nanofabricated, biofunctionalized arrays to study the fundamental relationship between spatial order and function in biochemical systems. These 'nanoscale bioarrays' will be fabricated using leading edge nanofabrication technology to allow investigation of structure-function relationships on the molecular scale, i.e. a few to tens of nanometers. The arrays will be organized hierarchically, with unit cells (comprising one or more biofunctionalized 2-10 nm metal dots) organized into micron-sized domains, and patterned in mm-size areas. Each domain will comprise identical unit cells, and the unit cell geometry will be systematically varied from domain to domain, in order to allow for straightforward assay techniques on the micron scale. The nanoscale bioarray technique will be applied to three biological investigations: 1, the study of the dependence of binding of large cytoskeletal proteins on the spatial arrangement of ligands; 2, the study of the effect of ordering cytoplasmic dynein molecules on microtubule-dependent motility; 3, the seeding of protein crystals.

Intellectual Merit:
This project attempts to push the limits of nanofabrication technology in order to interface with biological systems. It will employ a "top-down" approach to study and control "bottom-up" assembly, function and synthesis of these systems. Each sub-project will use nanofabrication technology to extend a biological question or problem beyond where currently available techniques will allow. The project is organized around a central theme and fabrication technique, which will allow for rapid technology development. The project addresses the research and education theme "Biosystems at the Nanoscale."

Broader Impacts:
This project will have many broader impacts. The advances in the use of solid-state nanofabrication to address biological and chemical problems will enhance research infrastructure in ways that will impact areas of biological science beyond just cytoskeleton-based motility or protein crystallization. The participation of young scientists-in-training in this interdisciplinary environment will foster development of a cadre of future scientists with the necessary knowledge and cultural and technical skills to successfully pursue novel multidisciplinary science and technology. Undergraduate students will also participate in the research, including students drawn from institutions in the New York City area with significant minority enrollment. The Principal Investigator will draw on his experience as a New York City public high school teacher to extend outreach to the K-12 level.

This nanomanufacturing research program aims to engineer arrays of dissimilar biomolecules for the purpose of studying increasingly complex biomolecular interactions. Advanced lithographic patterning will be used to create molecular-scale binding posts on solid surfaces. Different biomolecules, such as proteins and peptides, will be chemically assembled on the posts. The biomolecules will be organized in a variety of geometric arrangements, and the position of each molecule will be precisely determined. The arrays will be characterized by different microscopy techniques in order to optimize the placement accuracy and chemical selectivity of the process. A range of molecular densities, nanometer-scale spacings and geometric arrangements will be explored, and their effects on binding interactions between different biomolecules will be measured and quantified. The arrays will then be applied to the study of cellular response to the geometric organization of different proteins that are part of a cell's environment.

The ability to control the placement and organization of individual molecules is a key challenge in nanoscience and nanotechnology. The types of nano-scale arrayed surfaces developed in this program represent an important step towards manufacturing with molecular precision. They can be applied to a broad assortment of cellular and biomolecular systems and can be used for assembly of heterogeneous molecular species over a wide range of length scales. Applications in medical diagnostics, tissue engineering and therapeutic treatment are possible. Notably, the research in this program is highly interdisciplinary. It integrates tools and techniques originally developed by the semiconductor industry for the manufacture of electronic devices with biosystems in order to create new functionality at the nanoscale. The students and post-docs who train in this program will represent a new class of scientists who are comfortable working across traditional scientific boundaries.