OLED Pixel Defining Layer Using Half-Tone Mask
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing number of mask processes in manufacturing organic light emitting display devices (OLEDs) leads to higher production costs, necessitating a method to reduce the number of mask processes while maintaining device performance.
Innovation Solution
The implementation of an organic light emitting display device design that includes an external light blocking pattern and a thick insulating interlayer, which reduces the number of mask processes required in the manufacturing method by using a half-tone mask for forming the pixel defining layer and planarization layer, thereby minimizing the number of mask processes to six.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of mask processes is increased to achieve high definition resolution, then the display quality is improved, but the manufacturing cost is significantly increased
Solution Approach 1:
The patent combines multiple mask processes into a single mask process by designing a half-tone mask pattern that simultaneously defines the pixel defining layer and planarization layer. This merging approach reduces the number of mask processes from multiple to one, thereby significantly reducing manufacturing cost while maintaining high definition display quality
Solution Approach 2:
The patent uses half-tone mask technology which changes the optical parameters of the mask to create varying thickness regions in the deposited layers. This parameter change allows a single mask process to achieve what previously required multiple mask processes, reducing manufacturing complexity and cost
2Ease of manufacture
If the number of mask processes is reduced to decrease manufacturing cost, then the manufacturing cost is reduced, but the difficulty of achieving high definition resolution may increase
Solution Approach 1:
The half-tone mask creates local variations in layer thickness, with different regions having different thicknesses to serve different functions. The pixel defining layer has varying thickness to define pixel boundaries while the planarization layer maintains uniform thickness for surface flatness, achieving high definition quality with a single mask process
Solution Approach 2:
The patent introduces a new dimension of control by using half-tone mask optical density variations rather than relying on multiple sequential mask processes. This dimensional change in the masking approach allows simultaneous definition of multiple layers with different thickness requirements in a single process
3Device complexity
If a thin insulating interlayer is used, then the device structure is simpler, but the channel region of the semiconductor element is not adequately protected
Solution Approach 1:
The patent applies preliminary action by forming the pixel defining layer with increased thickness in specific regions before subsequent processing steps. This preliminary thickening provides advance protection to the channel region of the semiconductor element, preventing contamination or damage in later manufacturing steps while maintaining overall structural simplicity
Data Source
AI summary
An organic light emitting display device, including a substrate, a first conductive layer pattern on the substrate, a first insulation layer pattern on the first conductive layer pattern, a first semiconductor layer pattern on the first insulation layer pattern, a gate insulation layer pattern on the gate insulation layer pattern, a gate electrode on the gate insulation layer pattern, a planarization layer on the gate electrode, the planarization layer including a first protruding portion protruded in a first direction perpendicular to an upper surface of the substrate, a lower electrode on the first protruding portion, a pixel defining layer exposing at least a portion of the lower electrode, the pixel defining layer covering opposite side portions of the first protruding portion, a light emitting layer on the lower electrode, and an upper electrode on the light emitting layer.