Dual Spatial Light Modulator Lithography for Pattern Accuracy
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Solution Overview
Problem
Traditional maskless lithography methods, such as those using liquid crystal on silicon (LCOS) or digital micromirror devices (DMD), face challenges with slow modulation speed and diffraction issues, leading to inaccurate and inefficient pattern formation on photoresist layers, particularly in thick photoresist exposure.
Innovation Solution
An exposure device that employs a combination of first and second spatial light modulators to modulate the phase and amplitude of a laser, respectively, allowing for precise control of the exposure pattern by interfering and offsetting the laser phases and amplitudes to form accurate patterns on the photoresist layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DMD is used for exposure, then exposure speed is improved, but pattern accuracy deteriorates due to diffraction causing light to not concentrate 100% in the area to be exposed
Solution Approach 1:
The patent divides the spatial light modulation function into two separate devices: DMD for amplitude modulation and LCOS for phase modulation. This segmentation allows each device to specialize in one function, with DMD handling light intensity control and LCOS handling phase correction to compensate for diffraction effects, thereby maintaining both high exposure speed and pattern accuracy
Solution Approach 2:
The patent combines DMD and LCOS in a dual-modulation system where both devices work together on the same laser beam. The DMD performs amplitude modulation while the LCOS performs phase modulation, and their combined effect produces high-quality exposure patterns that leverage the strengths of both technologies while mitigating their individual weaknesses
2Manufacturing precision
If LCOS is used for exposure, then pattern accuracy can be maintained, but exposure time increases due to slow liquid crystal modulation speed
Solution Approach 1:
The patent segments the modulation functions by assigning amplitude control to DMD (fast response) and phase control to LCOS (precise control). This allows the system to achieve high exposure speeds through DMD's fast amplitude switching while maintaining pattern accuracy through LCOS's precise phase modulation
Solution Approach 2:
The patent implements dynamic modulation where the DMD rapidly switches amplitude levels while the LCOS dynamically adjusts phase values. This dynamic coordination between the two devices enables the system to achieve both high speed and high precision by leveraging the fast response of DMD and the precise control of LCOS
3Adaptability or versatility
If maskless lithography is used, then manufacturing flexibility is improved by omitting mask procedures, but pattern precision deteriorates due to inability to control laser phase
Solution Approach 1:
The patent introduces LCOS as an intermediary device between the laser source and the photoresist. This intermediary enables phase modulation of the laser beam, providing the precision control typically associated with mask-based systems while maintaining the flexibility of maskless lithography. The LCOS acts as a programmable phase mask that can be dynamically adjusted
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 more precise and sharp exposure patterns, improving the yield and accuracy of the developed patterns by dynamically adjusting the laser parameters during the exposure process.
Implementation Method 1
each being used for reflecting the laser after the phase of the laser irradiated on the first spatial light modulator is modulated
Implementation Method 2
each being used for reflecting the laser after the amplitude of the laser irradiated on the second spatial light modulator is modulated
Implementation Method 3
each being used for reflecting the laser after the phase of the laser irradiated on the first spatial light modulator is modulated first pixel
Implementation Method 4
due to diffraction, the light is often not 100% concentrated in the area to be exposed
Implementation Method 5
The laser reflected by the second spatial light modulator is irradiated on the photoresist layer to form an exposure pattern
Data Source
AI summary
An exposure device includes a laser source, a first spatial light modulator, a second spatial light modulator and a controller. The laser source is provided for emitting a laser. The first spatial light modulator is irradiated by the laser and used for modulating the phase of the laser irradiated on the first spatial light modulator before reflecting the laser. The second spatial light modulator is irradiated by the laser reflected from the first spatial light modulator and used for modulating the amplitude of the laser irradiated on the second spatial light modulator before reflecting the laser. The laser reflected by the second spatial light modulator is irradiated on a photoresist layer to form an exposure pattern.