Dual-Layer Gate Insulating Structure for OLED Semiconductor Reliability
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Solution Overview
Problem
In organic light emitting diode (OLED) display devices with metal oxide-based semiconductor elements, a short channel length leads to increased dispersion of threshold voltage and reduced photoelectric reliability and scalability, due to excessive oxygen supply from insulating layers contacting the active layer.
Innovation Solution
A dual-layer gate insulating structure is implemented, where the first layer with a lower nitrogen content and lower oxygen levels is used to prevent excessive oxygen supply, and the second layer with higher nitrogen content and oxygen levels allows controlled oxygen diffusion to the active layer during a heat treatment process, enhancing electron mobility and maintaining semiconductor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the channel length of the active layer is decreased to reduce the size of the metal oxide-based semiconductor element, then the device size is reduced, but the dispersion of threshold voltage increases and photoelectric reliability decreases
Solution Approach 1:
A buffer layer is introduced between the substrate and the active layer to control oxygen supply to the channel region. This intermediary layer prevents excessive oxygen from the substrate while allowing controlled oxygen diffusion to improve carrier concentration and reduce threshold voltage dispersion, thereby maintaining reliability in short-channel devices
Solution Approach 2:
The nitrogen concentration in the buffer layer is optimized as a key parameter. By adjusting the nitrogen content to specific ranges (e.g., 1×10^20 to 1×10^21 atoms/cm³), the buffer layer's oxygen release characteristics are controlled, enabling reliable operation of short-channel semiconductor elements
2Reliability
If an insulating layer directly contacts the active layer to provide oxygen to the channel region, then the dispersion of threshold voltage decreases, but the driven range of the semiconductor element shifts
Solution Approach 1:
The buffer layer is positioned specifically at the substrate-active layer interface where oxygen control is most critical. This localized oxygen supply mechanism provides oxygen exactly where needed (in the channel region) without causing excessive oxygen accumulation that would shift the driven range, achieving both threshold voltage stability and proper device operation
3Reliability
If oxygen is provided to the active layer to reduce threshold voltage dispersion, then the threshold voltage stability improves, but excessive oxygen supply shifts the driven range
Solution Approach 1:
The nitrogen-containing buffer layer serves as a controlled oxygen release medium. It acts as an intermediary that supplies oxygen at a controlled rate and quantity, preventing both oxygen deficiency (which causes threshold voltage dispersion) and oxygen excess (which shifts the driven range), thereby achieving balanced device performance
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 improves photoelectric reliability and channel length scalability of the semiconductor element, preventing the shift in driven range and maintaining functionality even with a short channel region, while reducing manufacturing costs by integrating oxygen transfer and heat treatment in a single processing stage.
Implementation Method 1
the second layer with higher nitrogen content and oxygen levels allows controlled oxygen diffusion to the active layer during a heat treatment process
Implementation Method 2
allows controlled oxygen diffusion to the active layer during a heat treatment process
Data Source
AI summary
An organic light emitting diode display device includes a substrate, an active layer disposed on the substrate and including a metal oxide-based semiconductor, a gate electrode disposed on the active layer, an insulating layer disposed on the gate electrode, source and drain electrodes disposed on the insulating layer, a light emitting element on the source and drain electrodes, and a gate insulating layer between the active layer and the gate electrode. The gate insulating layer includes first and second gate insulating layers. The first gate insulating layer directly contacts the active layer and has a first amount of nitrogen. The second gate insulating layer is disposed on the first gate insulating layer and has a second amount of nitrogen that is different from the first amount of nitrogen.