Light-Shielding Layer Blocks UV in Polysilicon TFTs
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Solution Overview
Problem
In the manufacturing of display panels, UV light exposure affects polysilicon layers in thin film transistors, leading to threshold voltage drift and requiring a lengthy annealing process, which increases production time and decreases productivity.
Innovation Solution
Incorporating a light-shielding layer, specifically an amorphous silicon layer of 600 Å to 1500 Å thickness, between the polysilicon layers and light-emitting structures to block UV light, preventing its transmission to the polysilicon layers and eliminating the need for an annealing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If UV light exposure is used in manufacturing, then light-emitting structures can be formed, but polysilicon layers experience threshold voltage drift
Solution Approach 1:
An amorphous silicon layer is introduced as an intermediary between the polysilicon layer and the light-emitting structure. This intermediate layer absorbs UV light before it reaches the polysilicon layer, preventing threshold voltage drift while allowing the manufacturing process to proceed normally.
Solution Approach 2:
The harmful UV light exposure is converted into a beneficial effect by using the amorphous silicon layer to absorb the UV energy. The UV light that would otherwise damage the polysilicon layer is now utilized to form or modify the amorphous silicon protective layer, turning a harmful process into a useful one.
2Reliability
If annealing process is applied to correct threshold voltage drift, then polysilicon layer stability is improved, but production time increases
Solution Approach 1:
The amorphous silicon layer is formed in advance during the manufacturing process, before UV light exposure occurs. This preliminary protective layer prevents threshold voltage drift from occurring in the first place, eliminating the need for subsequent annealing processes and reducing production time.
3Object-affected harmful factors
If amorphous silicon layer thickness is increased, then UV light blocking capability is improved, but material usage increases
Solution Approach 1:
The thickness of the amorphous silicon layer is optimized to a specific range (600-1500 Å) where it provides sufficient UV light blocking capability while minimizing material consumption. This parameter optimization balances protective function with material efficiency.
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
The light-shielding layer effectively prevents UV light from affecting the polysilicon layers, avoiding threshold voltage drift and reducing production time while improving productivity by eliminating the annealing process.
Implementation Method 1
a light-shielding layer for blocking ultraviolet (UV) light that is located between the polysilicon layer and the light-emitting structures
Data Source
AI summary
A display panel includes a base substrate, and thin film transistors positioned on the base substrate. Each thin film transistor includes a polysilicon layer. The display panel further includes a light-shielding layer for blocking ultraviolet (UV) light that is located at a side of the polysilicon layer away from the base substrate. An orthographic projection of the polysilicon layer on the substrate is in a range of an orthographic projection of the light-shielding layer on the substrate.