OLED Thin Film Transistor Gate Segmentation for Aperture Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Active matrix OLED displays face challenges in achieving a higher aperture ratio and maintaining favorable characteristics in both on and off states due to limitations in thin film transistor design and manufacturing methods.
Innovation Solution
The OLED display design incorporates a substrate with a first and second semiconductor layer, gate electrodes of different widths, and a lightly doped region between the channel and source/drain regions, allowing for improved transistor performance and aperture ratio through precise doping and layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate electrodes of different widths are used to form lightly doped regions, then the aperture ratio is improved and transistor characteristics in on and off states are enhanced, but the device structure and manufacturing process become more complex
Solution Approach 1:
The gate electrode structure is segmented into multiple gates with different widths positioned at different locations. The first gate has a wider width to form a lightly doped region, while the second gate has a narrower width for standard channel control. This segmentation allows different regions to have optimized doping characteristics, improving transistor reliability in both on and off states without requiring complete redesign of the entire device
Solution Approach 2:
Different regions of the semiconductor device are given different local qualities through the use of gates with different widths. The region under the first wider gate receives a lighter doping level to improve off-state characteristics, while the region under the second narrower gate maintains standard doping for optimal on-state performance. This local differentiation resolves the contradiction by allowing tailored optimization in different areas
2Reliability
If a lightly doped region is formed between channel and source/drain regions, then transistor stability and mobility are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The lightly doped region is formed through preliminary doping action before final device completion. By using the first wider gate to define and dope the lightly doped region in an early manufacturing stage, the structure is pre-configured with optimized doping profiles. This preliminary action reduces the need for subsequent precise adjustments, thereby improving transistor stability while managing manufacturing precision requirements
Solution Approach 2:
The first wider gate acts as an intermediary structure that facilitates the formation of the lightly doped region. It serves as a mask and doping source that mediates between the doping process and the final device structure. This intermediary approach allows controlled doping without requiring extremely precise direct positioning, thus improving reliability while moderating manufacturing precision demands
3Area of stationary object
If multiple gate electrodes with different widths are implemented, then the aperture ratio increases, but the ease of manufacture decreases
Solution Approach 1:
The aperture area is segmented into regions controlled by different gates with different widths. This segmentation allows the aperture ratio to be increased by optimizing the width of each gate segment independently. The first wider gate contributes more to the aperture area while still forming the lightly doped region, and the second narrower gate provides precise channel control, together achieving higher aperture ratio without sacrificing manufacturability through systematic design
Data Source
AI summary
An organic light-emitting diode (OLED) display having thin film transistors (TFTs) is disclosed. In one aspect, TFTs of the OLED display include a substrate and a first semiconductor layer formed over the substrate and including first channel, source, and drain regions and a lightly doped region between the first channel region and the first source and drain regions. The OLED display also includes a second semiconductor layer formed over the substrate and including second channel, source, and drain regions. The OLED display further includes first and second gate electrodes formed over the first semiconductor layer and a third gate electrode formed over the second semiconductor layer. The width of the second gate electrode is less than that of the first gate electrode and the lightly doped region overlaps a portion of the first gate electrode and does not overlap the second gate electrode.