Multi-head Modulator Lithographic Writer Beam Splitting
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Solution Overview
Problem
Current lithographic writers are limited in printing speed due to the single final lens design, which results in visible defects like mura when increasing the sweep length, and there is a need for further speed enhancement without introducing mura effects.
Innovation Solution
A scanning lithographic laser writer with a multi-head modulator arrangement that splits and modulates the laser input beam into multiple beams for each writing head, allowing for increased printing speed by displacing the beams in the sweep direction, thereby increasing the number of parallel beams without extensive changes to existing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sweep length is increased to improve printing speed, then the printing speed increases, but visible defects called mura appear in the printed masks
Solution Approach 1:
The patent divides the single writing head into multiple writing heads (first writing head and second writing head), each handling a portion of the sweep. This segmentation allows the system to achieve higher printing speed by parallel processing while maintaining mask quality by distributing the exposure across multiple heads with overlapping zones that eliminate mura defects.
Solution Approach 2:
The patent introduces a new dimension by positioning multiple writing heads at different locations along the sweep direction. The first and second writing heads are offset from each other, creating a multi-dimensional exposure pattern that covers the entire mask area more efficiently without creating visible defects.
2Productivity
If the number of parallel beams is increased in the common single final lens, then the printing speed increases, but the device complexity increases significantly
Solution Approach 1:
Instead of increasing the number of beams in a single complex optical system, the patent segments the system into multiple independent writing heads, each with its own final lens. This approach achieves higher parallelism while keeping each optical subsystem relatively simple and manageable.
Solution Approach 2:
The patent uses two writing heads providing overlapping exposure zones, which is more than the minimum single-head configuration. This partial redundancy in the form of overlap ensures complete coverage and eliminates defects while maintaining manageable system complexity.
3Productivity
If the sweep length is doubled using new deflector, then the printing speed improves, but the overlap zones become too spaced causing detectable imperfections
Solution Approach 1:
The patent segments the sweep into multiple smaller sweeps handled by different writing heads. The first writing head performs a first sweep and the second writing head performs a second sweep with overlap, creating multiple smaller overlap zones that are closely spaced and therefore not detectable as defects.
Solution Approach 2:
The patent applies different functions to different parts of the mask by using multiple writing heads with localized exposure zones. Each writing head optimizes its local exposure parameters, and the overlapping zones ensure uniform quality across the entire mask area.
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 increases printing speed proportionally with the number of writing heads while minimizing mura effects, improving critical lithographic parameters like placement and critical dimension uniformity.
Implementation Method 1
The multi head modulator arrangement is configured to split and modulate an input beam originating from the laser source into n modulated beams, where n≥1, for each of the m writing head arrangements by use of an acoustic-optical crystal
Implementation Method 2
The laser beam(s) is(are) focused by this lens to a respective small spot. The position of this spot is typically rapidly and periodically changing causing the beam trajectory to form one line
Data Source
AI summary
A scanning lithographic laser writer, comprises a substrate holder, an irradiation arrangement and a control unit. The irradiation arrangement has a laser source, a multi head modulator arrangement and at least two writing head arrangements. The irradiation arrangement is arranged for providing laser light, via the multi head modulator arrangement to the writing head arrangements to irradiate a substrate plane. The control unit is configured for controlling a relative mechanical displacement between a substrate holder and the writing head arrangements, and for controlling a sweep of laser light exiting therefrom. The multi head modulator arrangement is configured to split and modulate an input beam into at least one modulated beam for each of the writing head arrangements by use of an acoustic-optical crystal. The writing head arrangements are positioned to displace laser light exiting from the writing head arrangements with respect to each other.