Barrel-Shaped Nanopore Structure for Precise Size Control
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Solution Overview
Problem
Conventional methods for forming nanopores, such as direct patterning, face challenges in achieving small feature sizes with high accuracy due to surface roughness and variations in nanopore sizes, which compromise the performance of nanopore devices.
Innovation Solution
The formation of nanopore structures is achieved through a method involving the creation of a silicon germanium (SiGe) pillar, followed by thermal oxidation to form an oxide shell with a unique barrel-shaped configuration, and subsequent removal of the SiGe pillar core to create a nanopore with larger openings at the ends and a smaller center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If direct patterning is used to form nanopores, then the manufacturing process is simple, but the nanopore size precision and surface quality deteriorate
Solution Approach 1:
The patent applies preliminary action by forming a sacrificial SiGe pillar structure before creating the final nanopore. The SiGe pillar is formed with precise dimensions using standard lithography and etching processes, then undergoes thermal oxidation to create a SiO2 shell with controlled thickness. This preliminary structured approach allows the final nanopore dimensions to be precisely controlled by the oxide shell thickness rather than direct patterning, resolving the contradiction between manufacturing simplicity and precision.
Solution Approach 2:
The patent introduces an intermediary oxide shell (SiO2) that mediates between the SiGe pillar and the final nanopore structure. This oxide shell acts as a template that defines the nanopore dimensions with high precision while allowing the SiGe core to be removed selectively. The intermediary oxide layer enables precise nanopore formation without requiring direct patterning of the final pore structure, thus maintaining manufacturing simplicity while achieving high precision.
2Device complexity
If direct patterning is used to form nanopores, then the process steps are reduced, but surface roughness and nanopore size variation increase
Solution Approach 1:
The SiGe pillar formation with precise dimensions serves as a preliminary structure that ensures uniform nanopore dimensions. The thermal oxidation process that follows creates a consistent oxide shell thickness, which directly determines the final nanopore size. This preliminary structured approach reduces surface roughness and minimizes nanopore size variation, thereby improving device reliability despite adding some process steps.
Solution Approach 2:
The patent utilizes parameter changes through thermal oxidation to transform the SiGe pillar into a SiO2 shell with controlled thickness. By controlling oxidation temperature, time, and atmosphere, the oxide shell thickness can be precisely adjusted, which in turn controls the final nanopore dimensions. This parameter-controlled approach ensures uniform nanopore sizes and reduces surface roughness, improving device reliability.
3Ease of manufacture
If conventional etching is used for nanopore formation, then the process is straightforward, but achieving small feature sizes becomes difficult
Solution Approach 1:
The patent forms a SiGe pillar with the desired small diameter using standard lithography and etching processes as a preliminary step. The thermal oxidation then creates an oxide shell around this pillar, and selective removal of the SiGe core produces the final nanopore. This preliminary structured approach allows conventional etching to be used for the SiGe pillar formation, maintaining process simplicity, while the oxidation and core removal steps enable precise control of the final nanopore diameter at the nanoscale.
Solution Approach 2:
The oxide shell serves as an intermediary that enables the transition from micrometer-scale lithography patterns to nanometer-scale nanopores. The SiGe pillar with initial dimensions is transformed through oxidation into a structure with precisely controlled nanopore dimensions. This intermediary approach allows conventional lithography and etching to be used for the initial structure, maintaining manufacturing ease, while achieving small nanopore features through the oxidation-mediated transformation.
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 allows for the precise control of nanopore size and reduces surface roughness, resulting in improved accuracy and performance of nanopore devices, such as enhanced DNA sequencing capabilities.
Implementation Method 1
annealing the SiGe pillar in an oxygen-containing ambient under conditions sufficient to form an oxide shell surrounding a condensed SiGe pillar core
Implementation Method 2
depositing a dielectric material into the at least one pore to form a nanopore at a center of the dielectric material
Data Source
AI summary
Nanopore structures are provided. In one aspect, a nanopore structure includes: an oxide shell surrounding a nanopore, wherein openings on both ends of the nanopore have a diameter D1, and a center of the nanopore has a diameter D2, wherein D1>D2. In another aspect, the nanopore structure includes: a first film disposed on a substrate; a second film disposed on the first film; at least one pore extending through the first film and the second film; a dielectric material disposed in the at least one pore; and a nanopore at a center of the dielectric material in the at least one pore, wherein a top opening to the nanopore has a first diameter d1, and a bottom opening to the nanopore has a second diameter d2, wherein d2>d1. Methods of forming the nanopore structures are also provided.