Maskless Exposure Apparatus Stitching Stripe Elimination
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Solution Overview
Problem
Maskless exposure apparatuses face challenges in achieving uniform exposure across large substrates due to limited exposure width in the sub-scan direction, leading to stitching areas where adjacent exposure heads overlap, resulting in stitching stripes and non-uniform exposure doses.
Innovation Solution
A maskless exposure apparatus with a stage, exposure head, beam measurer, calculator, and controller that measures beam data, calculates step distances to ensure uniform exposure dose distribution, and aligns exposure heads to minimize stitching stripes by determining an optimal step distance within a tolerance range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple exposure heads are used to cover large substrates, then the exposure area is increased, but stitching stripes appear in the overlapping areas due to non-uniform exposure dose
Solution Approach 1:
The patent applies preliminary action by measuring beam data (position, power, size) before the stitching exposure process and calculating the optimal step distance in advance. The controller uses these pre-calculated parameters to position exposure heads and adjust beam intensity, ensuring uniform exposure dose in stitching areas before the actual exposure begins, thereby preventing stitching stripe formation.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the step distance between exposure heads and beam intensity based on measured beam characteristics. The controller modifies exposure parameters (positioning coordinates, beam power) to compensate for variations in stitching areas, maintaining uniform exposure dose across the entire substrate including overlapping regions.
2Area of stationary object
If the exposure width is increased to cover large substrates, then the number of exposure heads is reduced, but the beam spot array size must be enlarged which reduces resolution
Solution Approach 1:
The patent resolves this contradiction by transitioning from a single-dimension approach (enlarging beam spot array) to a multi-dimensional solution. It maintains small beam spot arrays for high resolution while extending coverage in the sub-scan direction through multiple exposure heads with optimized step distances. The system achieves large area coverage by adding spatial arrangement of multiple heads rather than enlarging individual beam spots.
Solution Approach 2:
The patent applies segmentation by dividing the large substrate into multiple exposure regions covered by separate exposure heads, each maintaining high resolution with small beam spot arrays. The segmentation allows each head to operate at optimal resolution while the coordinated stepping and overlapping of multiple heads achieve comprehensive high-resolution coverage of the entire large substrate.
3Area of stationary object
If stepping is performed in the sub-scan direction to cover the entire substrate, then the exposure area is increased, but stitching areas with overlapping exposure create non-uniform dose distribution
Solution Approach 1:
The patent implements feedback by measuring actual beam data (position, power, size) from each exposure head and using this information to calculate and adjust step distances. The controller receives feedback from beam measurements and dynamically optimizes positioning and exposure parameters to ensure uniform dose distribution in stitching areas, compensating for variations introduced by the stepping process.
Data Source
AI summary
Disclosed herein are a maskless exposure apparatus configured to perform exposure by tilting a beam spot array with respect to a scan direction (Y-axis direction) thus preventing stitching stripes and a stitching method using the same. A step distance, in which exposure dose uniformity in a stitching area is within a tolerance range, is calculated using actual position data of beam spots constituting the beam spot array on an exposure plane, and if necessary, using beam power data and/or beam size data. As exposure is performed based on image data conforming to the step distance, the stitching area has a uniform exposure dose, enabling exposure without stitching stripes.