TFT Display Metal Layer Layout for Light Leakage Blocking
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Solution Overview
Problem
The existing manufacturing processes for display devices with thin film transistors face issues such as light leakage currents and defects like crosstalk due to the exposure of the active layer to light, which necessitate the use of a separate light shielding film, increasing manufacturing complexity and costs.
Innovation Solution
A display device manufacturing method where a metal layer and a semiconductor layer are formed using the same process, with specific portions of the metal layer overlapping, not overlapping, or partially overlapping the semiconductor layer, simplifying the process and reducing light exposure, and including a dummy light blocking layer to prevent light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate light shielding film is provided under the active layer to prevent light leakage, then light leakage current and crosstalk defects are prevented, but the manufacturing process complexity and cost increase
Solution Approach 1:
The patent combines the light shielding function with the existing metal layer (source/drain electrode) by extending the metal layer to overlap with the semiconductor layer. This merging eliminates the need for a separate light shielding film, reducing manufacturing process complexity while maintaining the light blocking function to prevent light leakage current and crosstalk defects
Solution Approach 2:
The metal layer is designed to serve multiple functions: it acts as both the source/drain electrode and the light shielding film. By making the metal layer extend beyond the semiconductor layer boundary, it simultaneously provides electrical connection and light blocking, reducing the total number of layers and process steps
2Object-affected harmful factors
If a separate mask process is added to provide a light shielding film, then light leakage is prevented, but manufacturing cost and process time increase
Solution Approach 1:
The light shielding function is merged into the metal layer formation process by extending the metal layer pattern. This eliminates the need for a separate mask process, reducing manufacturing process time while still providing effective light blocking to prevent light leakage
Solution Approach 2:
The light shielding structure is formed preliminarily during the metal layer deposition step before subsequent processing steps. By establishing the light blocking function early in the process, no additional time-consuming steps are required later
Data Source
AI summary
A display device includes: a first substrate; a plurality of metal layers on the first substrate and separated from each other; a buffer layer on the metal layer; a semiconductor layer on the buffer layer; a gate conductive layer on the semiconductor layer; a data conductive layer connected to the semiconductor layer; and a light-emitting element connected to the data conductive layer, wherein the metal layer includes a first portion partially overlapping the semiconductor layer in a third direction perpendicular to the surface of the first substrate, a second portion where the metal layer completely overlaps the semiconductor layer in the third direction, and a third portion where the metal layer does not overlap the semiconductor layer in the third direction.