Polarization Interference Laser Scanning for Sub-Diffraction Fine Patterns
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Solution Overview
Problem
The laser exposure method for forming fine patterns is limited by the diffraction limit of the exposure lens, resulting in a thicker line width compared to the ion beam method, which restricts the precision of patterns that can be created.
Innovation Solution
An apparatus employing polarization interference using a calcite wave plate to space apart S and P waves, allowing them to form an interference laser beam with a predetermined pattern direction near the focus, combined with a 2-axis module unit for switching the interference pattern direction, reduces line width and enables the formation of various pattern forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional laser exposure method is used to form fine patterns, then the formation speed is fast, but the line width is limited and thicker compared to ion beam method
Solution Approach 1:
The laser beam is segmented into two separate beams with different polarizations (S-wave and P-wave) that travel along different optical paths. This segmentation allows each beam to be independently controlled and focused, enabling the creation of finer interference patterns that overcome the diffraction limit of conventional single-beam laser exposure methods.
Solution Approach 2:
A polarization beam splitter is introduced as an intermediary device to separate the incident laser beam into S-wave and P-wave components. This mediator enables the creation of distinct optical paths for each polarization state, which is essential for forming the interference pattern with reduced line width while maintaining fast formation speed.
2Manufacturing precision
If the line width of laser beam is reduced to form finer patterns, then the manufacturing precision is improved, but the diffraction limit of exposure lens restricts further reduction
Solution Approach 1:
The invention transitions from a single-beam approach to a dual-beam interference approach, adding the dimension of wave interference. By superimposing two coherent laser beams with different polarizations, the system creates an interference pattern with line width below the conventional diffraction limit, effectively bypassing the reliability constraint imposed by the diffraction limit.
Solution Approach 2:
The invention changes the fundamental parameter of beam formation from direct single-beam exposure to interference-based pattern formation. By controlling the phase and polarization parameters of two separate beams, the system achieves sub-diffraction line widths that would be impossible with conventional single-beam methods, thereby overcoming the diffraction limit constraint.
3Manufacturing precision
If polarization interference is employed to reduce line width, then the manufacturing precision is improved, but the device complexity increases due to additional optical components
Solution Approach 1:
The polarization beam splitter serves multiple functions: it separates the incident laser beam into S-wave and P-wave components, directs them along different optical paths, and enables subsequent interference. This multi-functionality reduces the need for additional separate components, thereby mitigating the increase in device complexity while achieving improved manufacturing precision.
Solution Approach 2:
The invention merges the functions of beam separation, path differentiation, and interference pattern formation into a unified optical system. By combining these functions through the polarization-based approach, the system achieves complex functionality without proportionally increasing device complexity, as the polarization states inherently provide the necessary differentiation without requiring separate mechanical systems.
4Manufacturing precision
If a fixed interference pattern direction is used, then the manufacturing precision in one direction is improved, but the adaptability to form various pattern forms is limited
Solution Approach 1:
The invention introduces dynamic control of the interference pattern direction by allowing independent adjustment of the optical paths for S-wave and P-wave beams. This dynamic capability enables the system to adapt the interference pattern orientation to match the desired scanning direction, providing both high manufacturing precision and versatility for forming various pattern forms including concentric circles, straight lines, and complex geometries.
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
The solution effectively reduces the line width of formed patterns and allows for the creation of finer patterns in multiple directions, surpassing the limitations of conventional laser exposure methods by aligning the interference pattern direction with the movement of the exposure lens, thereby enhancing pattern precision and versatility.
Implementation Method 1
a calcite wave plate configured to refract at least one of the S wave and the P wave, polarized by the polarization plate, in a specific direction so that paths of the S wave and the P wave are spaced apart from each other at a fine interval
Implementation Method 2
the exposure lens transmits the S and P waves to form an interference laser beam having a predetermined interference pattern direction near a focus
Data Source
AI summary
An apparatus for forming fine patterns by employing polarization interference in a laser scanning method comprises a laser generator; a calcite wave plate configured to refract at least one of the S wave and the P wave, polarized by the polarization plate, an analyzer configured to make coincident with each other the polarization directions of the S wave and the P wave having the paths spaced apart from each other by the calcite wave plate; an exposure lens; an exposure head; an X stage; and a rotation stage configured to move the substrate mounting unit around a Z axis which is a vertical axis.