Maskless Exposure Device Focus Control for Non-Flat Substrates
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Solution Overview
Problem
Maskless exposure devices face defects such as stains in display panels due to uneven light application caused by non-flat substrate surfaces, as the focus point of the optical head is typically centered, leading to inadequate focus control across different regions of the substrate.
Innovation Solution
A maskless exposure device that includes a stage, optical head, and light source, where the optical head uses a distance measurement sensor and focus controller to determine an average-focus distance by measuring best-focus distances across various substrate regions, ensuring even light application and precise focus control using a beam splitter, digital micro-mirror device, and optical system with multiple lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the focus point of the optical head is centered on the substrate, then the distance measurement can be simplified, but the light application becomes uneven due to non-flat substrate surfaces
Solution Approach 1:
The patent divides the substrate into multiple regions (first region and second region) and determines separate best-focus distances for each region based on their respective surface heights. This allows each region to have optimized focus parameters tailored to its local surface characteristics, resolving the contradiction between simplified centralized focus control and the need for uniform light application across non-flat surfaces.
2Productivity
If a single best-focus distance is used for the entire substrate, then the exposure process is simplified, but wiring width precision deteriorates in regions with different surface heights
Solution Approach 1:
The patent determines multiple best-focus distances corresponding to different regions of the substrate based on their respective surface heights. By adjusting the focus distance parameter according to regional surface variations, the system maintains precise wiring width control across all regions while managing the exposure process efficiently through automated parameter selection.
3Ease of operation
If the optical head is positioned at a fixed distance from the substrate, then the device operation is simplified, but focus accuracy deteriorates across regions with varying surface heights
Solution Approach 1:
The patent implements dynamic focus distance adjustment by determining multiple best-focus distances for different substrate regions and selecting the appropriate focus distance based on the current exposure region. The focus controller dynamically modifies the optical head-to-substrate distance according to the measured surface height of the active region, thereby maintaining high focus accuracy while preserving ease of operation through automated control.
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 solution ensures consistent and precise light irradiation across the substrate, reducing defects like stains by maintaining uniform focus across different regions, thereby improving the quality of patterned wiring widths and overall substrate exposure.
Implementation Method 1
The distance measurement sensor may be configured to measure a distance between the optical head and an exposing-surface of the substrate
Implementation Method 2
The optical head irradiates the light according to an average-focus distance to the substrate
Data Source
AI summary
A maskless exposure device includes a stage on which a substrate is disposed, an optical head, and an optical source part. The optical head irradiates light to the substrate. The light source part provides the optical head with a light. The optical head irradiates the light, according to an average-focus distance, to the substrate. The average-focus distance is determined by averaging best-focus distances for a plurality of regions of the substrate, respectively.