Stacking 2D Layers Using Target Frames for Alignment
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Solution Overview
Problem
The challenge of forming arbitrary 3D structures by assembling 2D material layers, particularly patterned layers, remains unsolved due to difficulties in maintaining the accuracy of lateral and vertical alignment of layers during stacking.
Innovation Solution
A method involving the stacking of free-standing 2D layers as membranes, without the use of sacrificial membranes, using a target frame with an opening and a carrier frame to achieve precise lateral alignment and structuring of layers, allowing for the creation of complex 3D van-der-Waals multilayer structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pick-and-lift technique with sacrificial membranes is used to assemble 2D layers, then the layers can be transferred and stacked, but the alignment precision deteriorates due to the complexity of membrane handling and carrier removal
Solution Approach 1:
The patent removes the sacrificial membrane carrier from the system entirely. Instead of using a membrane carrier that requires dissolution or removal, the invention directly handles free-standing 2D layers, eliminating the complex carrier removal step and its associated alignment errors
Solution Approach 2:
The patent introduces a novel intermediary system consisting of a target frame with opening and carrier frame that enables direct manipulation of free-standing 2D layers. This intermediary system provides the necessary mechanical support and alignment references without requiring sacrificial membrane carriers
2Manufacturing precision
If free-standing 2D layers are manipulated directly without sacrificial membranes, then the alignment precision improves, but the handling difficulty increases due to the fragility of thin membranes
Solution Approach 1:
The carrier frame and target frame serve as intermediary structures that provide mechanical support and manipulation interfaces for the fragile free-standing 2D layers. These frames enable precise handling and alignment while the 2D layers remain free-standing without sacrificial membrane carriers
Solution Approach 2:
The invention utilizes the inherent flexibility and thin-film nature of the 2D layers themselves as the functional element, eliminating the need for sacrificial membranes. The free-standing 2D layers are directly manipulated using the frame structures, turning the previously problematic fragility into a manageable characteristic through proper mechanical support
3Manufacturing precision
If conventional lithographic techniques are used to pattern 2D layers, then the patterning process is simple, but the lateral alignment accuracy between stacked layers deteriorates
Solution Approach 1:
The patent performs the patterning of 2D layers before stacking, using lithographic techniques to create the desired structures in each layer independently. The frames then serve as alignment references during stacking, ensuring that the pre-patterned layers are laterally aligned with high precision
Solution Approach 2:
The target frame with opening and carrier frame act as intermediary alignment references that enable precise lateral alignment between stacked layers. These frames provide stable mechanical references that maintain the positional relationships established during patterning through the stacking process
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 precise alignment of 2D layers with a lateral offset of less than 10 nm, allowing for the creation of almost arbitrary 3D structures with a wide variety of properties and functional devices.
Implementation Method 1
assembling stacks of 2D materials... van-der-Waals heterostructures... stacking of two-dimensional layers into three-dimensional multilayer structures
Data Source
Figure 1(a)~1(j)
Figure 2
Figure 3~5c
AI summary
A method to form three-dimensional (3D) van-der-Waals multilayer structures comprises stacking two-dimensional (2D) layers (10, 100). In a step a., at least two of the 2D layers (10, 100) are provided. In a step b., a first of the 2D layers (10) is placed onto a support (15). In a step c., a second of the 2D layers (100) is placed onto the previously placed first 2D layer (10), thereby producing a stack (200) of two layers. Optionally step c. is repeated with one or more further of the 2D layers, thereby increasing the height of the stack (200). The 2D layers (10,100) are free-standing membranes. The support (15) comprises or is a target frame (20) defining an opening (21), wherein the free-standing membranes are placed in such a way that they span the opening (21) of the target frame (20). Besides the method, an apparatus for conducting the method and the obtained van-der-Waals multilayer structures are described.