Top-Gate Self-Aligned MOS TFT Light-Shielding Layer Design
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Solution Overview
Problem
Metal oxide semiconductor TFTs experience negative threshold voltage drift and floating gate effects due to light sensitivity, leading to unstable operation, which existing methods fail to fully address.
Innovation Solution
A top-gate self-aligned metal oxide semiconductor TFT manufacturing method involving a light-shielding layer below the active layer, connected to the source, to prevent negative threshold voltage drift and floating gate effects, using a plasma treatment to reduce oxygen content and maintain semiconductor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a metal light-shielding layer is disposed below the active layer to prevent negative threshold voltage drift, then light sensitivity is reduced, but floating gate effect occurs causing unstable operation
Solution Approach 1:
The patent extracts the light-shielding function from a separate metal layer and integrates it into the source electrode structure. The source electrode is extended beneath the active layer to serve dual purposes: as an electrical contact and as a light-shielding layer, thereby eliminating the floating gate effect while maintaining protection against negative threshold voltage drift.
Solution Approach 2:
The patent merges the source electrode and light-shielding layer into a single integrated structure. The source electrode is extended under the active layer to combine the electrical contact function with the light-shielding function, eliminating the need for a separate metal light-shielding layer and preventing the floating gate effect.
2Ease of manufacture
If metal oxide semiconductor material is used to achieve high electron mobility, then manufacturing simplicity is improved, but light sensitivity increases causing threshold voltage instability
Solution Approach 1:
The patent introduces an intermediate light-shielding structure (the extended source electrode) between the light source and the metal oxide semiconductor active layer. This intermediary blocks harmful light from reaching the active layer while maintaining the simplicity of the manufacturing process using standard TFT fabrication techniques.
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 method effectively stabilizes the TFT's operation by preventing negative threshold voltage drift and floating gate effects, resulting in improved working stability and performance.
Implementation Method 1
conducting a plasma treatment to reduce oxygen content of the metal oxide semiconductor material
Data Source
AI summary
The present disclosure provides a top-gate self-aligned metal oxide semiconductor TFT and a manufacturing method thereof. By providing a light-shielding layer below an active layer to protect the active layer from light irradiation and prevent the TFT from generating a negative threshold voltage drift phenomenon. Further, by connecting the light-shielding layer to the source, a stable voltage is generated on the light-shielding layer to avoid the floating gate effect, so as to improve the working stability of the TFT effectively. The top-gate self-aligned metal oxide semiconductor TFT produced by the method of the present disclosure does not generate negative threshold voltage drift phenomenon and floating gate effect, resulting in good working stability.