OLED Display Silicon Layer Current Isolation
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Solution Overview
Problem
Conventional organic light emitting diode (OLED) displays require patterning of active layers to prevent current flow between thin film transistors, which increases manufacturing time and cost.
Innovation Solution
The OLED display employs a substrate with polysilicon lines and amorphous silicon lines that are integrally formed without patterning, where the amorphous silicon lines connect adjacent polysilicon lines, forming one silicon layer, and the active regions are defined within these lines, preventing current flow between adjacent transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active layers are patterned to prevent current flow between thin film transistors, then current isolation is improved, but manufacturing time and cost increase
Solution Approach 1:
An amorphous silicon layer is introduced as an intermediary between adjacent polysilicon active layers. This amorphous silicon layer has high resistivity and acts as a current blocking layer, preventing current flow between adjacent thin film transistors without requiring patterning of the active layers themselves.
Solution Approach 2:
The invention changes the material parameter of the layer between active layers from conductive (patterned polysilicon) to highly resistive (amorphous silicon). By controlling the resistivity parameter through material selection and deposition conditions, current isolation is achieved without patterning.
2Reliability
If active layers are patterned to prevent current flow between thin film transistors, then current isolation is improved, but manufacturing cost increases
Solution Approach 1:
An amorphous silicon layer is introduced as an intermediary between adjacent polysilicon active layers. This amorphous silicon layer has high resistivity and acts as a current blocking layer, preventing current flow between adjacent thin film transistors without requiring patterning of the active layers themselves.
Solution Approach 2:
The invention extracts the current isolation function from the active layer patterning process and places it in a separate amorphous silicon layer. This separation allows the active layers to remain unpatterned while still achieving current isolation through the dedicated amorphous silicon barrier layer.
3Reliability
If active layers are patterned to prevent current flow between thin film transistors, then current isolation is improved, but device complexity increases
Solution Approach 1:
An amorphous silicon layer is introduced as an intermediary between adjacent polysilicon active layers. This amorphous silicon layer has high resistivity and acts as a current blocking layer, preventing current flow between adjacent thin film transistors without requiring patterning of the active layers themselves.
Solution Approach 2:
The amorphous silicon layer is formed as a continuous layer across the substrate, merging the isolation function into a single uniform layer rather than requiring multiple patterned layers. This simplifies the overall device structure while maintaining current isolation.
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 approach reduces manufacturing time and cost while effectively preventing current flow between adjacent active layers, enabling the production of OLED displays without the need for patterning, thereby streamlining the manufacturing process.
Implementation Method 1
irradiating a laser on to the amorphous silicon layer to form a silicon layer including a plurality of polysilicon lines spaced from each other and extending in a first direction and a plurality of amorphous silicon lines between the adjacent polysilicon lines
Data Source
AI summary
An organic light emitting diode display includes: a substrate; a first thin film transistor including a first active region on the substrate; a second thin film transistor connected to the first thin film transistor and including a second active region spaced from the first active region; and a silicon layer on the substrate and including a plurality of polysilicon lines spaced from each other and extending in a first direction and a plurality of amorphous silicon lines between the adjacent polysilicon lines and extending in the first direction, wherein the first active region and the second active region are in different polysilicon lines of the plurality of polysilicon lines.