Curved Semiconductor Layer for OLED Pixel Circuit
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Solution Overview
Problem
Existing display apparatuses face challenges in achieving high resolution and compact designs due to limitations in space efficiency and process variations during the manufacturing of thin-film transistors and capacitors, particularly in organic light-emitting diode (OLED) displays, where the complexity of semiconductor layer patterns and photomask designs hinder the formation of efficient current paths and increase process variations.
Innovation Solution
The display apparatus incorporates a driving semiconductor layer with curved portions and specific width and length configurations in a pixel circuit, along with a photomask design featuring corresponding patterns, to enhance the driving channel region's length and reduce process variations, thereby improving the driving range of gate voltage and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the semiconductor layer uses a conventional rectangular pattern, then the manufacturing process is simple, but the current path length is insufficient and process variations increase
Solution Approach 1:
The semiconductor layer incorporates curved portions instead of sharp corners, creating a meandering path that increases the current path length within the same footprint. This curved geometry reduces process variations by providing more uniform stress distribution and better alignment tolerance during manufacturing, while maintaining manufacturing feasibility through standard photolithography processes.
Solution Approach 2:
The invention transforms the conventional two-dimensional rectangular semiconductor layer into a three-dimensional meandering structure by adding curvature in the vertical dimension. This allows the current path to extend longer without increasing the planar footprint, effectively utilizing the Z-direction curvature to achieve longer channel length while maintaining compact device area.
2Reliability
If the pixel circuit occupies larger area to accommodate longer driving channel, then the driving range of gate voltage increases, but the display resolution and compactness deteriorate
Solution Approach 1:
By curving the semiconductor layer in a meandering pattern, the invention packs a longer driving channel into a smaller pixel area. The curved portions allow the current path to fold back on itself, effectively multiplying the channel length without proportionally increasing the pixel footprint, thus maintaining high resolution while achieving sufficient driving range.
Solution Approach 2:
The meandering semiconductor layer creates a nested-like structure where the current path folds within the pixel boundary, similar to how a long string can be nested within a small box. This allows the driving channel to be contained within the pixel area while maintaining the necessary length for adequate gate voltage control range.
3Length of moving object
If the photomask uses complex patterns to form curved semiconductor layers, then the current path length increases, but the manufacturing complexity and cost increase
Solution Approach 1:
The curved portions in the semiconductor layer can be formed using standard photolithography with appropriately designed photomasks. The curvature radius is chosen to be large enough to be manufacturable with conventional processes while still achieving significant current path length extension. This balances the need for long current paths with manufacturing ease.
Data Source
AI summary
A semiconductor device includes a semiconductor layer over a substrate. The semiconductor layer changes direction at least twice and has at least two different widths in the same plane. The length of a current path through the semiconductor layer is greater than a shortest path through the semiconductor layer in the same plane.