Nanoscale Shift Register Fabrication via Nanoimprinting
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Solution Overview
Problem
Current nanoscale electronic circuits face challenges in fabricating robust and inexpensive demultiplexing components that can efficiently distribute input signals to individual nanowires, particularly at molecular dimensions, due to limitations in photolithography-based methods and the reliability of passive and active electronic components at nanowire junctions.
Innovation Solution
A nanoscale shift register is fabricated using nanoimprinting techniques to create nanowires and nanowire segments, with hysteretic resistive nanowire junctions acting as latches, and field-effect transistors controlling electrical connections between pairs of latches, allowing for the distribution of input signals to individual nanowires through alternating electrical connections and signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography-based methods are used to fabricate nanoscale circuits, then manufacturing precision can be maintained at current scales, but further size decreases are approaching physical limits and fabrication becomes increasingly difficult
Solution Approach 1:
The patent replaces photolithography-based mechanical fabrication methods with a self-assembly approach using block copolymers. The block copolymer system spontaneously forms nanoscale patterns through thermodynamic self-organization, eliminating the need for traditional photolithographic patterning at molecular dimensions and enabling feature sizes below the diffraction limit of light.
Solution Approach 2:
The block copolymer system performs self-patterning and self-assembly to create nanoscale circuit features. The polymer blocks spontaneously organize into periodic structures with controlled spacing and morphology, providing self-directed fabrication that achieves high precision without external patterning tools, thereby overcoming photolithography's physical limits.
2Quantity of substance
If nanowire crossbars are used to fabricate dense nanoscale circuits, then circuit density increases, but reliability of passive and active electronic components at nanowire junctions remains problematic
Solution Approach 1:
The patent employs block copolymers composed of chemically distinct blocks (e.g., polystyrene and polyisoprene) that self-assemble into composite nanoscale structures. These composite materials provide both the structural framework for high-density circuits and the chemical functionality for reliable junctions, with different blocks serving different functional roles in the circuit elements.
Solution Approach 2:
The block copolymer system creates locally differentiated structures where specific polymer block compositions and morphologies are positioned at specific locations to provide tailored properties. For example, one block may form conductive pathways while another forms insulating barriers, ensuring reliable component behavior at each nanoscale junction while maintaining overall high density.
3Adaptability or versatility
If demultiplexing components are fabricated at nanoscale dimensions, then signal distribution to individual nanowires is enabled, but fabrication of robust and inexpensive components becomes challenging
Solution Approach 1:
The block copolymer-based fabrication approach provides a universal platform that can simultaneously create multiple nanoscale circuit features including demultiplexing components, logic elements, and interconnects through a single self-assembly process. This multi-functional approach enables robust signal distribution capability while simplifying manufacturing by eliminating the need for separate fabrication steps for different component types.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient demultiplexing of input signals to individual nanowires, overcoming the limitations of existing technologies by providing a reliable and cost-effective method for constructing dense nanoscale circuitry, facilitating the integration of nanoscale components into larger circuits.
Implementation Method 1
a nanoimprinting-resist layer applied above a silicon-on-insulator substrate is nanoimprinted to form troughs and trough segments
Implementation Method 2
The silicon layer exposed at the bottom of the troughs and trough segments is then etched
Implementation Method 3
a conductive material is deposited into the troughs to form nanowires
Implementation Method 4
The exposed surfaces of nanowires are coated with a protective coating
Data Source
AI summary
One embodiment of the present invention is a method for fabricating a nanoscale shift register. In a described embodiment, a nanoimprinting-resist layer applied above a silicon-on-insulator substrate is nanoimprinted to form troughs and trough segments. The silicon layer exposed at the bottom of the troughs and trough segments is then etched, and a conductive material is deposited into the troughs to form nanowires and into the trough segments to form nanowire segments. The exposed surfaces of nanowires are coated with a protective coating, and the conductive material of the nanowire segments is then removed to produce trough segments etched through the nanoimprinting resist and the silicon layer. A dielectric column between configurably resistive columns in orientations non-parallel with the orientation of the nanowires is fabricated above the nanowires, gate signal lines are fabricated above, and parallel with, the dielectric column, and latch-control signal lines are fabricated above, and parallel with, the configurably resistive columns. Additional embodiments of the present invention are directed to fabricating devices and circuits with nanoscale features by partitioning the nanoscale features into sets, and separately coating the features of each set prior to one or more subsequent steps.