Deposition Mask Reinforcement Pattern for Warpage Control
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Solution Overview
Problem
The deformation of masks during deposition processes due to stress induction complicates precise patterning in flat panel display devices, particularly in organic light emitting diode (OLED) devices, making it difficult to form thin films like organic emission layers accurately.
Innovation Solution
A mask for deposition is designed with a base layer, pattern insulating layer, and reinforcement pattern, where the reinforcement pattern has a higher thermal expansion coefficient than the base layer, offsetting tensile stress and reducing warpage, ensuring precise patterning by maintaining the mask's structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask is used for deposition to form thin films, then patterning can be achieved, but the mask deforms due to stress induced during the deposition process
Solution Approach 1:
The patent applies local quality by creating a reinforcement pattern only in the peripheral area of the mask where stress accumulation occurs, while leaving the central patterned area unchanged. This localized reinforcement approach addresses the specific problem of stress-induced deformation in the periphery without affecting the patterning capability of the central region.
Solution Approach 2:
The patent uses composite materials by combining the base mask material with a reinforcement material having different thermal expansion characteristics. The reinforcement pattern is formed using a material with a thermal expansion coefficient that compensates for the stress induced during deposition, creating a composite structure that maintains structural stability while preserving patterning precision.
2Stability of the object's composition
If the mask structure is reinforced to prevent deformation, then structural stability improves, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the mask into distinct functional areas: a central patterned area for deposition and a peripheral reinforcement area for stress compensation. The reinforcement pattern is segmented into discrete elements rather than a continuous structure, reducing material usage and structural complexity while maintaining stability.
Solution Approach 2:
The reinforcement pattern is applied locally only where needed (in the peripheral area) rather than throughout the entire mask. This localized approach minimizes the addition of structural elements, thereby reducing overall device complexity while achieving the desired structural stability improvement.
3Stability of the object's composition
If a reinforcement pattern with different thermal expansion coefficient is added, then stress-induced deformation is reduced, but manufacturing complexity increases
Solution Approach 1:
The reinforcement pattern is formed before the deposition process using the same photolithography and etching tools and processes already in place for mask manufacturing. By performing the reinforcement pattern formation as a preliminary step in the existing manufacturing flow, the patent avoids adding separate manufacturing complexity while achieving stress compensation.
Solution Approach 2:
The reinforcement pattern serves multiple functions: it provides structural reinforcement, compensates for thermal expansion stress, and can be integrated with the existing mask patterning process. This multi-functionality reduces the need for separate manufacturing steps, thereby simplifying the overall manufacturing process despite the additional functional requirement.
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 mask design effectively reduces deformation, allowing for precise deposition of thin films on substrates, enhancing the accuracy of patterning in display devices.
Implementation Method 1
a pattern insulating layer including a material having a thermal expansion coefficient that is greater than a thermal expansion coefficient of the base layer... a reinforcement pattern in the peripheral area, including a material having a thermal expansion coefficient that is different from the thermal expansion coefficient of the base layer
Data Source
AI summary
A deposition mask including: unit areas spaced apart from each other and a peripheral area surrounding the unit areas in a plan view; a base layer having a first surface and a second surface opposite to the first surface, the base layer defining first openings respectively corresponding to the unit areas; a pattern insulating layer including a material having a thermal expansion coefficient that is greater than a thermal expansion coefficient of the base layer, the pattern insulating layer having pattern portions respectively corresponding to the unit areas on the first surface of the base layer, each of the pattern portions defining a plurality of slits; and a reinforcement pattern in the peripheral area, the reinforcement pattern including a material having a thermal expansion coefficient that is different from the thermal expansion coefficient of the base layer, the reinforcement pattern being covered by the pattern insulating layer.