Photomask Overlap Monitoring for Scan Alignment Accuracy
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Solution Overview
Problem
The accuracy and reliability of the photo-lithography process in display devices, such as OLEDs and LCDs, are compromised due to scanning movement distortions, non-uniformity in unit laser beam sizes, and mis-alignment, leading to patterning errors and deviations in forming thin film transistors and pixel areas.
Innovation Solution
A photomask design incorporating monitoring mask patterns with oblique line shapes and overlapping regions, along with a method to adjust exposure conditions based on these patterns, ensures precise alignment and reliability by detecting and correcting patterning errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is divided into multiple unit laser beams for scanning exposure, then productivity is improved through faster processing, but manufacturing precision deteriorates due to distortion in scanning movement direction and non-uniformity in unit laser beam sizes
Solution Approach 1:
The patent introduces monitoring mask patterns with oblique line shapes in the overlapping regions of adjacent scan regions before the actual exposure process. These monitoring patterns serve as reference markers that allow for preliminary detection and correction of scanning distortions and beam uniformity issues, enabling compensation measures to be taken before the main patterning exposure, thus maintaining both high productivity and manufacturing precision
2Productivity
If scanning exposure is used to irradiate the photomask, then productivity is improved through efficient area coverage, but manufacturing precision deteriorates due to mis-alignment between adjacent scan regions
Solution Approach 1:
The patent implements a feedback mechanism by incorporating monitoring mask patterns that overlap in the scanning direction. These patterns provide reference information that enables detection of mis-alignment between adjacent scan regions. The measured mis-alignment data is then fed back to correct the positioning and ensure accurate alignment, allowing the system to maintain both high scanning efficiency and precise alignment accuracy
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 proposed photomask and method enhance the accuracy and reliability of the photo-lithography process, enabling high-precision formation of oblique and diagonal line patterns in display devices, reducing patterning errors and deviations.
Implementation Method 1
A photo-lithography process includes performing an exposure process. For example, an exposure apparatus may be aligned with a mask pattern to irradiate an object with light. Accordingly, a desired pattern image may be transferred to an etching object.
Data Source
AI summary
A photomask has scan regions irradiated with unit beam areas in a scan direction, and an overlapping region including portions of adjacent scan regions included among the scan regions. The adjacent scan regions are adjacent in a sweeping direction of the scan regions. The sweeping direction is perpendicular to the scan direction of the scan regions. The photomask includes a monitoring mask pattern that overlaps the overlapping region or is adjacent to a boundary of the overlapping region, and the monitoring mask pattern includes a side having an oblique line shape inclined with respect to the sweeping direction.