Oxide TFT Source-Drain Structure That Preserves Channel Width
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Solution Overview
Problem
The formation of source and drain regions in thin film transistors of display apparatuses leads to physical damage and reduces the width of the channel region due to etching and impurity diffusion, affecting the electrical characteristics and image quality.
Innovation Solution
The implementation of source and drain semiconductor patterns with n-type impurities, surrounded by insulating layers, maintains the same material composition as the channel region, reducing resistance and preventing impurity diffusion, thus protecting the active pattern and channel region integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If etching and doping processes are used to form source and drain regions, then the resistance of source and drain regions is reduced, but the active pattern is physically damaged and the channel region width is reduced due to impurity diffusion
Solution Approach 1:
The source and drain regions are formed as separate semiconductor patterns (first and second semiconductor patterns) that are disposed on opposite sides of the channel region, rather than forming them through a single etching and doping process. This segmentation allows each region to be independently controlled and prevents impurity diffusion into the channel region.
Solution Approach 2:
A third semiconductor pattern is introduced as an intermediary barrier between the first and second semiconductor patterns. This intermediate pattern prevents impurity diffusion from the source and drain regions into the channel region, while still allowing the source and drain regions to maintain their low resistance characteristics.
2Reliability
If etching process is used to form source and drain regions, then the resistance of source and drain regions is reduced, but the active pattern surface is physically damaged
Solution Approach 1:
The source and drain regions are formed by depositing semiconductor materials in predetermined positions before the channel region is fully formed. This preliminary action avoids the need for subsequent etching processes that would damage the active pattern surface, as the semiconductor patterns are already in place to serve as source and drain regions.
Solution Approach 2:
The mechanical etching process is replaced with a deposition process where semiconductor materials are deposited to form source and drain regions. This substitution eliminates the physical damage caused by etching while still achieving the desired low resistance characteristics through the deposited semiconductor layers.
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 configuration maintains the channel region width and electrical characteristics, preventing physical damage and improving image quality by reducing impurity diffusion and etching processes.
Implementation Method 1
The first insulating layer is disposed between the source semiconductor pattern and the active pattern and between the drain semiconductor pattern and the active pattern
Data Source
AI summary
A display apparatus is provided. The display apparatus may include a light-emitting device and a pixel driving circuit electrically connected to the light-emitting device. The pixel driving circuit may supply a driving current corresponding to a data signal to the light-emitting device according to a gate signal. For example, the pixel driving circuit may include at least one thin film transistor. The thin film transistor may include an active pattern comprising an oxide semiconductor. A source region of the active pattern overlaps a source semiconductor pattern, and a drain region of the active pattern overlaps a drain semiconductor pattern. The source semiconductor pattern and the drain semiconductor pattern may include n-type impurities. A channel region of the active pattern may be outside the source semiconductor pattern and the drain semiconductor pattern. Thus, in the display apparatus, reliability of the pixel driving circuit may be improved.