Photomask Light Focusing Elements Sub-Wavelength Patterning
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Solution Overview
Problem
Conventional photolithography techniques are unable to produce nano-scale patterns with spatial periods less than the wavelength of light sources, and existing methods using self-organized microspheres are limited by the need for reusable masks and are inefficient for large-area, repetitive patterns.
Innovation Solution
A method involving a photomask with micro- or nano-light focusing elements that are positioned at a distance from the light-sensitive material, allowing light interference to create patterns with spatial periods smaller than the elements, achieved by adjusting the distance between the light-sensitive layer and the photomask to optimize constructive interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography techniques are used, then manufacturing process is simple, but manufacturing precision is insufficient for nano-scale patterns below wavelength limit
Solution Approach 1:
The photomask is segmented into an array of discrete micro- or nano-light focusing elements (spheres, cylinders, or cones) arranged in a periodic pattern. Each element independently focuses light to create a pattern feature, enabling sub-wavelength precision by dividing the masking function into multiple localized focusing units rather than using a continuous mask structure
Solution Approach 2:
Micro- or nano-spheres are used as intermediary light focusing elements between the light source and the photoresist layer. These spherical elements act as optical mediators that concentrate and focus light through their lensing effect, enabling precise pattern formation at spatial periods below the wavelength of light by mediating the optical interaction between illumination and photoresist
2Productivity
If self-organized micro-spheres are deposited before exposure, then nano-scale patterns can be generated, but micro-spheres cannot be reused and deposition must be repeated for each sample
Solution Approach 1:
The photomask with light focusing elements is prepared in advance and positioned at a controlled distance from the photoresist layer before exposure. This preliminary positioning allows the mask to be reused across multiple samples without requiring re-deposition, as the pre-formed mask structure maintains its optical functionality through repeated use
Solution Approach 2:
The photomask serves as a reusable template that copies the periodic pattern of light focusing elements onto multiple photoresist layers. By maintaining a fixed distance between the mask and photoresist, the same mask can repeatedly imprint identical nano-scale patterns across different samples, eliminating the need for re-deposition of micro-spheres for each new substrate
3Adaptability or versatility
If micro-spheres are used as lenses, then pattern spatial period equals micro-sphere diameter, but adjustment of spatial period requires different micro-sphere sizes
Solution Approach 1:
The system introduces dynamic adjustability by varying the distance between the photomask and the photoresist layer. This dynamic parameter (gap distance) allows continuous tuning of the pattern spatial period independent of the light focusing element size, providing versatility without requiring physical changes to the mask structure itself
Solution Approach 2:
The invention changes the controlling parameter for spatial period from micro-sphere diameter to photomask-to-photoresist distance. By making this parameter substitution, the system decouples pattern periodicity from element size, allowing spatial period adjustment through positional parameter variation rather than requiring different sized micro-spheres
4Manufacturing precision
If photomask is held at optimized distance for constructive interference, then patterns with spatial period less than element size are achieved, but alignment precision requirements increase
Solution Approach 1:
The system employs feedback mechanisms to monitor and control the distance between the photomask and photoresist layer during exposure. By implementing real-time distance measurement and adjustment, the system maintains the optimized gap required for constructive interference, compensating for positioning variations and ensuring consistent sub-wavelength pattern formation across production batches
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 creation of micro- or nano-scale patterns with spatial periods less than 1 micrometer, allowing for more precise control over pattern dimensions and enabling the reuse of the photomask, thereby improving efficiency and versatility in manufacturing nanostructures.
Implementation Method 1
a photomask comprising a support and a layer of micro- or nano-light focusing elements fixed to the support
Implementation Method 2
each micro-sphere acts as a micro-lens, focusing the light radiations on the photoresist layer
Implementation Method 3
light radiations passing through at least two adjacent micro- or nano-light focusing elements and which interfere constructively with each other
Implementation Method 4
developing the layer of light sensitive material so as to obtain the micro- or nano-scale patterned layer of material
Data Source
AI summary
The invention relates to a method for making a micro- or nano-scale patterned layer of material by photolitography, comprising steps of:positioning a photomask between a light source and a layer of light sensitive material, said mask comprising a support and a layer of micro- or nano-light focusing elements fixed to the support,activating the light source so that the light source emits light radiations through the mask towards a surface of the layer of light sensitive material,developing the layer of light sensitive material so as to obtain the micro- or nano-scale patterned layer of material,wherein, during exposure of the layer of light sensitive material to light radiations, the photomask is positioned relative to the light sensitive layer so that the distance between the surface of the light sensitive layer and the layer of micro- or nano-light focusing elements is greater than a back focal length of the micro- or nano-light focusing elements.