Hybrid Oxide-Silicon TFT Pixels With Overlapping Capacitors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electronic device displays, such as liquid crystal and organic light-emitting diode displays, often face issues like non-uniformity, excessive leakage currents, insufficient drive strengths, and poor area efficiency due to suboptimal thin-film transistor circuitry.
Innovation Solution
The implementation of hybrid thin-film transistor structures combining semiconducting oxide and silicon transistors, with capacitor structures overlapping the oxide transistors, and the use of different transistor types for drive and switching functions to optimize performance, including the incorporation of oxide and silicon transistors in both display pixels and driver circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thin-film transistor circuitry is used in display pixels and driver circuitry, then manufacturing is simpler, but the display exhibits non-uniformity, excessive leakage currents, insufficient drive strengths, and poor area efficiency
Solution Approach 1:
The transistor circuitry is segmented into two distinct types: oxide thin-film transistors (oxides TFTs) for pixels requiring low leakage currents (such as liquid crystal display pixels and organic light-emitting diode display pixels), and silicon thin-film transistors (silicon TFTs) for pixels requiring high drive strengths (such as light-emitting diode display pixels) or for switching functions. This segmentation allows each transistor type to be optimized for its specific function, resolving the contradiction between reliability and device complexity.
Solution Approach 2:
Different transistor types are assigned to different locations within the display based on local performance requirements. Oxide TFTs are used in locations where low leakage is critical, while silicon TFTs are used in locations where high drive strength is critical. This local differentiation of quality allows the display to achieve overall uniformity and performance without requiring a single complex transistor design everywhere.
2Loss of energy
If oxide transistors are used for drive transistors coupled to light-emitting diodes, then leakage currents are reduced, but switching speed may be limited
Solution Approach 1:
The patent changes the material parameter of the transistor channel from oxide to silicon specifically for switching transistors, where high switching speed is required. For drive transistors where low leakage is more critical, oxide material is used. This parameter change allows optimization of switching speed without compromising the low-leakage benefit in drive transistors.
3Speed
If silicon transistors are used for switching functions, then switching speed is improved, but leakage currents increase
Solution Approach 1:
The transistor functions are segmented such that silicon TFTs are used exclusively for switching functions where high speed is required and can tolerate higher leakage, while oxide TFTs are used for drive functions where low leakage is critical. This functional segmentation resolves the contradiction by matching transistor type to functional requirement.
Data Source
AI summary
An electronic device may include a display having an array of display pixels on a substrate. The display pixels may be organic light-emitting diode display pixels or display pixels in a liquid crystal display. In an organic light-emitting diode display, hybrid thin-film transistor structures may be formed that include semiconducting oxide thin-film transistors, silicon thin-film transistors, and capacitor structures. The capacitor structures may overlap the semiconducting oxide thin-film transistors. Organic light-emitting diode display pixels may have combinations of oxide and silicon transistors. In a liquid crystal display, display driver circuitry may include silicon thin-film transistor circuitry and display pixels may be based on oxide thin-film transistors. A single layer or two different layers of gate metal may be used in forming silicon transistor gates and oxide transistor gates. A silicon transistor may have a gate that overlaps a floating gate structure.