Stacked Metallized Grid Structures for High-Aspect Ratio Trenches
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Solution Overview
Problem
Conventional methods struggle to pattern vertical sidewalls with aspect ratios greater than 20 in silicon substrates using conventional photoresists, often resulting in re-sputtering and micro-masking defects, and traditional metal filling techniques are expensive and inefficient for high-aspect ratio trenches.
Innovation Solution
A method involving a patterned photoresist and aluminum mask for deep reactive ion etching to form high-aspect ratio trenches, followed by alignment and stacking of metallized grid structures using nano-particles and screen printing or roll printing to fill trenches with high-Z materials, reducing processing costs and increasing aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photoresists are used to pattern vertical sidewalls, then the patterning process is simple and low-cost, but the maximum achievable aspect ratio is limited to 20
Solution Approach 1:
The patent divides the single high-aspect-ratio trench structure into multiple lower-aspect-ratio segments that can be independently patterned and then stacked together. Each segment has a manageable aspect ratio that can be achieved with conventional photoresists, and the segments are combined to form the final high-aspect-ratio structure, thereby overcoming the 20:1 limitation while maintaining manufacturing simplicity.
Solution Approach 2:
The patent transitions from creating high aspect ratios within a single layer to achieving high effective aspect ratios through stacking multiple layers in the vertical dimension. By arranging multiple grid structures with trenches at different heights and bonding them together, the effective aspect ratio is multiplied without requiring each individual trench to have an extremely high aspect ratio.
2Manufacturing precision
If metal masking is used to pattern trenches, then higher aspect ratios can be achieved, but re-sputtering and micro-masking defects occur
Solution Approach 1:
By segmenting the trench structure into multiple parts across different layers, each individual trench has a lower aspect ratio that can be patterned with conventional photoresists without requiring metal masking. This eliminates the re-sputtering and micro-masking defects associated with metal masking while still achieving the overall high effective aspect ratio through stacking.
Solution Approach 2:
The patent uses conventional photoresists instead of expensive and defect-prone metal masks. The photoresist is applied, patterned, and then removed after serving its purpose as a temporary patterning layer during the etching process, providing a cost-effective and defect-free alternative to metal masking.
3Manufacturing precision
If traditional cleanroom-based metal filling methods are used, then deep trenches can be filled, but processing costs are high and efficiency is low
Solution Approach 1:
By dividing the deep trench into multiple shallower trenches across different layers, each trench can be filled more easily and cost-effectively. The segmented approach allows for simpler filling processes while maintaining complete metallization of the overall high-aspect-ratio structure through the stacked layers.
Solution Approach 2:
The patent replaces expensive cleanroom-based metal filling methods (electron-beam evaporation, sputtering, electroplating) with more cost-effective techniques such as screen printing or roll printing of metal nanoparticle suspensions. These alternative methods achieve sufficient metallization for the application at lower cost and with higher throughput.
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 the formation of high-aspect ratio trench structures with reduced defects and lower costs, scalable for various substrate sizes, improving the signal-to-noise ratio in X-ray imaging systems by increasing the effective aspect ratio and metal content in stacked structures.
Implementation Method 1
a plurality of nano-particles are suspended within the cured carrier fluid
Implementation Method 2
optically aligning a plurality of metallized grid structures on a substrate utilizing an optical camera of a wafer bonding system and fiducial marks on the substrate
Implementation Method 3
patterned photoresist and aluminum mask for deep reactive ion etching to form high-aspect ratio trenches
Data Source
AI summary
A method for forming a multi-layered, stacked grid structure includes aligning a first grid structure with a second grid structure, wherein both the first grid structure and the second grid structure each include a substrate in which a plurality of trenches are formed and a cured carrier fluid disposed within the plurality of trenches, and wherein a plurality of nano-particles are suspended within the cured carrier fluid. The method also includes, upon aligning the first grid structure and the second grid structure so that their respective plurality of trenches are aligned in the same orientation, joining the first grid structure and the second grid structure together to form the multi-layered, stacked grid structure.