LTPS Array Substrate Doping Structure for Heat Reduction
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Solution Overview
Problem
Low temperature poly-silicon (LTPS) TFTs in display devices face issues with excessive heat generation and leakage current due to impact ionization, affecting threshold voltage and carrier mobility, and existing solutions like lightly-doped drain (LDD) face challenges in balancing heat reduction and power consumption.
Innovation Solution
An array substrate design with a specific doping structure, including heavily-doped and lightly-doped regions, is implemented to reduce the horizontal electric field intensity and heat generation, featuring first and second lightly-doped regions of controlled lengths and ion injection concentrations, arranged in a horizontal direction to enhance the channel region's electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a lightly-doped drain (LDD) is formed to reduce heat and leakage current, then heat generation and leakage current are reduced, but power consumption increases and aperture ratio is adversely affected
Solution Approach 1:
The LDD structure is divided into multiple segments: a first LDD region and a second LDD region with different doping concentrations and lengths. The first LDD region has a doping concentration of 1×10^19 to 1×10^20 atoms/cm³ and length of 0.5-2 μm, while the second LDD region has a doping concentration of 1×10^18 to 1×10^19 atoms/cm³ and length of 1-3 μm. This segmentation allows each region to contribute differently to electric field distribution, effectively reducing heat and leakage current while minimizing the impact on aperture ratio.
Solution Approach 2:
Different regions of the LDD structure are assigned different doping concentrations and lengths to achieve local optimization. The first LDD region closer to the source/drain contact has higher doping concentration for better carrier injection, while the second LDD region extending toward the channel has lower doping concentration for better electric field distribution. This local quality differentiation resolves the contradiction between reducing harmful effects and maintaining aperture ratio.
2Object-affected harmful factors
If the LDD is made longer to reduce heat and leakage current, then heat reduction capability improves, but aperture ratio is adversely affected
Solution Approach 1:
The LDD structure is divided into two segments with different lengths: the first LDD region has length of 0.5-2 μm and the second LDD region has length of 1-3 μm. This segmentation achieves a total LDD length of 1.5-5 μm, which is sufficient to reduce heat generation through improved electric field distribution, while the distributed structure minimizes the overall area occupation compared to a single continuous LDD of equivalent total length.
Solution Approach 2:
The doping concentration and length parameters are optimized in a stepwise manner across different LDD regions. The first LDD region uses higher doping concentration (1×10^19 to 1×10^20 atoms/cm³) with shorter length (0.5-2 μm), while the second LDD region uses lower doping concentration (1×10^18 to 1×10^19 atoms/cm³) with longer length (1-3 μm). This parameter optimization achieves effective heat reduction while controlling the overall footprint to preserve aperture ratio.
3Area of stationary object
If the LDD is made shorter to maintain aperture ratio, then aperture ratio is improved, but heat reduction capability is lost
Solution Approach 1:
By dividing the LDD into two segments with different characteristics, the structure achieves effective heat reduction with a more compact overall footprint. The first LDD region (0.5-2 μm) provides initial electric field modulation close to the contact, while the second LDD region (1-3 μm) extends the field distribution effect. The segmented approach achieves heat reduction equivalent to longer LDD but with better aperture ratio preservation.
Solution Approach 2:
Different doping concentrations and lengths in the two LDD regions create local quality variations that maximize heat reduction efficiency within a compact area. The higher doped first LDD region (1×10^19 to 1×10^20 atoms/cm³) provides strong local field control near the contact, while the lower doped second LDD region (1×10^18 to 1×10^19 atoms/cm³) extends the effect toward the channel. This local quality differentiation achieves effective heat management with minimized area occupation.
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 design effectively reduces heat generation and leakage current while maintaining an optimal aperture ratio, improving the performance and quality of LTPS TFTs in display devices.
Implementation Method 1
excessive heat will be generated by the LTPS TFT due to impact ionization caused by electrons accelerated under the effect of a relatively large horizontal electric field
Implementation Method 2
the LDD has a relatively high resistance, which is equivalent to a serially-connected resistor of high resistance, the intensity of the horizontal electric field of the LTPS TFT can be reduced, thereby reducing the generated hot carriers due to impact ionization
Implementation Method 3
the distribution of the electric field in a channel of the LTPS TFT can be improved, thereby reducing the generated hot carriers due to impact ionization caused by electric field acceleration
Implementation Method 4
first lightly-doped region, a first non-doped region, a second lightly-doped region, a second non-doped region, a third lightly-doped region and a second heavily-doped region which are sequentially arranged in a horizontal direction
Data Source
AI summary
The present disclosure provides an array substrate, a manufacturing method thereof and a display device. The array substrate includes an active layer, a gate insulating layer and a gate electrode layer formed sequentially on a base substrate. The active layer includes a first heavily-doped region, a first lightly-doped region, a first non-doped region, a second lightly-doped region, a second non-doped region, a third lightly-doped region and a second heavily-doped region which are sequentially arranged in a horizontal direction.