Nanochannel Fabrication via Buried Silicon Oxide Etching
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Solution Overview
Problem
The challenge in HPLC systems is to fabricate nanochannels with precise control over submicron dimensions, as reducing bead size increases fluidic impedance and decreases flow rates, particularly in low-flow applications like proteomics, where high sensitivity is required, and current etching techniques struggle to maintain control over channel width and depth.
Innovation Solution
The use of buried silicon oxide technology allows for the selective etching of silicon oxide layers to create nanochannels with precise dimensions, employing high etch ratio pairs like silicon and silicon oxide, and controlling channel width through optimized etch times, enabling the fabrication of nanochannels with controlled flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If narrow channels (nanochannels) are used to achieve low flow rates, then flow rate is reduced, but channel dimension control becomes difficult
Solution Approach 1:
The patent introduces a mandrel structure as an intermediary element to define the nanochannel dimensions. The mandrel serves as a template that precisely controls the channel width and depth during fabrication, enabling accurate nanoscale dimension control without direct reliance on etching process precision alone.
Solution Approach 2:
The patent employs preliminary actions by forming the mandrel structure before creating the nanochannels. This pre-formed mandrel serves as a template that guides subsequent etching processes, ensuring precise channel dimensions are achieved through the intermediary structure rather than direct etching control.
2Ease of manufacture
If isotropic etching is used to fabricate nanochannels, then channel formation is achieved, but both channel width and depth are difficult to control
Solution Approach 1:
The mandrel acts as an intermediary that provides precise geometric constraints during etching. By having the etching process proceed along the walls of the pre-formed mandrel, both channel width and depth are controlled by the mandrel dimensions rather than by etching process parameters alone, significantly improving manufacturing precision.
Solution Approach 2:
The patent replaces direct mechanical control of etching processes with a template-based approach. Instead of controlling etching through process parameters, the physical template (mandrel) mechanically defines the channel geometry, substituting process control with structural constraint for improved precision.
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 method enables the precise fabrication of nanochannels with controlled flow rates, reducing stagnation areas and improving fluid flow, suitable for low-flow applications like proteomics, by leveraging the high etch ratio between silicon and silicon oxide, allowing for efficient fluid manipulation in microfluidic systems.
Implementation Method 1
etching a fluidic channel in the silicon oxide layer with at least one of the silicon layers as an etching stop
Implementation Method 2
employing high etch ratio pairs like silicon and silicon oxide
Data Source
AI summary
In some embodiments of the present invention, the buried silicon oxide technology is employed in the fabrication of fluid channels, particularly nanochannels. For example, a fluid channel can be made in a buried silicon oxide layer by etching the buried oxide layer with a method that selectively removes silicon oxide but not silicon. Thus, one dimension of the resulting fluid channel is limited by the thickness of the buried oxide layer. It is possible to manufacture a very thin buried oxide layer with great precision, thus a nanochannel can be fabricated in a controlled manner. Moreover, in addition to buried oxide, any pairs of substances with a high etch ratio with respect to each other can be used in the same way. Further provided are the fluid channels, apparatuses, devices and systems comprising the fluid channels, and uses thereof.