Electron Microscope Microchips With Doped Silicon Membrane Support
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Solution Overview
Problem
Low stress silicon nitride membranes used in electron microscopy are prone to cracking during sample preparation, and their deflection due to pressure gradients significantly reduces spatial resolution, making it difficult to achieve atomic resolution imaging, especially with liquid samples.
Innovation Solution
The method involves p-type silicon doping to reduce the etch rate and form a support structure with p-type doped silicon regions, allowing for the fabrication of microchips with high-density silicon nitride windows that minimize deflection and enhance resolution by using a patterned dopant mask layer and silicon nitride overlayer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thin LSN membranes are used for electron microscopy, then electron transparency and toughness are improved, but the membranes crack easily during sample preparation and manufacturing
Solution Approach 1:
The patent creates a composite structure consisting of a thin LSN membrane bonded to a thicker LSN support layer. This composite configuration provides the electron transparency of the thin membrane while the thicker support layer prevents cracking during sample preparation and manufacturing, thus resolving the contradiction between toughness and crack resistance.
2Adaptability or versatility
If LSN membranes are configured to encapsulate fluids, then liquid sample imaging is enabled, but pressure gradient induced deflection reduces spatial resolution
Solution Approach 1:
The patent employs a thin LSN membrane as a flexible encapsulating layer that can contain fluid samples while maintaining structural integrity. The membrane's flexibility allows it to conform to pressure gradients without excessive deflection, enabling both fluid encapsulation and acceptable spatial resolution for imaging.
3Ease of manufacture
If silicon substrates are used to support LSN membranes, then ease of manufacturing is improved, but anisotropic etching causes substrates to become wedged, making it difficult to position membranes close together
Solution Approach 1:
The patent divides the support structure into multiple independent silicon substrate regions, each supporting an individual LSN membrane. This segmentation allows each membrane to be positioned and processed independently, compensating for the wedging effect of anisotropic etching and enabling precise positioning of multiple membranes in an array while maintaining manufacturing ease.
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 reduces the deflection of silicon nitride windows, enabling higher resolution imaging by maintaining the integrity of the membrane and allowing for closer window spacing, thus improving the spatial resolution in electron microscopy.
Implementation Method 1
doping the first exposed silicon region in the silicon substrate with a p-type dopant to form a first p-type doped silicon region in the silicon substrate
Data Source
AI summary
Method for fabricating a microchip are provided which may comprise forming a dopant mask layer on a front side surface of a silicon substrate having the front side surface and an opposing back side surface; removing a portion of the dopant mask layer according to a pattern to form a first exposed silicon region in the silicon substrate and a first unexposed silicon region in the silicon substrate; doping the first exposed silicon region in the silicon substrate with a p-type dopant to form a first p-type doped silicon region in the silicon substrate; forming a silicon nitride layer on the front side surface of the silicon substrate comprising the first p-type doped silicon region and the first unexposed silicon region; and forming an opening in the silicon substrate from the opposing back side surface of the silicon substrate to provide a microchip comprising the silicon substrate having the opening, a first silicon nitride window positioned within the opening, and a support structure mounted to the first silicon nitride window, the support structure comprising the first p-type doped silicon region. The fabricated microchips and methods of using the microchips are also provided.