Thin Film Transistor Groove Light Shielding

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Solution Overview

Problem

Current OLED array substrates lack effective light shielding for lateral light incidence, which affects the performance of thin film transistors due to light reflection and leakage currents from side surfaces of the active layer.

Innovation Solution

Incorporating a light-shielding portion with a groove between the active layer and the base substrate, where the active layer is positioned within the groove, and using a spacer and light-shielding layer to reduce lateral light incidence, ensuring the side wall of the groove is on the periphery of the active layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a metallic light shield is used at the rear side of the array substrate, then light incident from the rear side is shielded, but light incident from the lateral side cannot be shielded and causes leakage currents

Engineering Contradiction:

Improvelight shielding effectivenessVSAvoidlight shielding structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent transitions from traditional planar light shielding (rear side only) to three-dimensional groove-based shielding. The groove structure extends the light shielding into the vertical dimension, creating side walls that block lateral light incidence while maintaining a compact footprint on the substrate surface.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The light shielding function is segmented into multiple components: the groove structure itself, the light shielding layer coating the groove, and the spacer layer. This segmentation allows each component to perform its specific function optimally while working together to provide comprehensive light shielding from both rear and lateral directions.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If the active layer is exposed without groove protection, then the device structure is simple, but light reflects multiple times between layers and incidents into the channel causing performance degradation

Engineering Contradiction:

Improvedevice structureVSAvoidthin film transistor performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The groove structure is formed before the active layer is deposited, creating a pre-positioned protective structure. The light shielding layer is then formed on the groove walls, establishing a complete light-blocking barrier before the active layer is exposed to light during operation, thereby preventing photo-generated carriers from forming in the channel.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The active layer is nested within the groove structure, with the light shielding layer coating the groove walls and the spacer layer providing additional protection. This nested arrangement ensures the active layer is surrounded and protected by multiple shielding layers, preventing light from reaching the channel region.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Object-affected harmful factors

If a light-shielding portion with groove is formed, then lateral light incidence is reduced, but the fabrication process becomes more complex

Engineering Contradiction:

Improvelateral light incidenceVSAvoidfabrication process

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The fabrication process merges multiple functions into integrated steps: the groove formation, light shielding layer deposition, and spacer layer formation are combined into a coordinated sequence. The light shielding layer and spacer layer are formed in the same fabrication region, reducing the number of separate processing steps and masks required.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively shields light from the side surfaces of the active layer, reducing leakage currents and enhancing the performance of the thin film transistors by minimizing the impact of incident light.

Implementation Method 1

forming a light-shielding portion between the active layer and the base substrate, the light-shielding portion comprising a groove... effectively shields light from the side surfaces of the active layer

Methodology Applied

Scientific EffectLight shielding: Absorption (EM radiation)

Data Source

PatentUS11302822B2Thin film transistor and fabrication method thereof, array substrate and fabrication method thereof

Publication Date: 2022.04.12 BOE TECHNOLOGY GROUP CO LTD

AI summary

A thin film transistor and a fabrication method thereof, an array substrate and a fabrication method thereof are disclosed. The thin film transistor includes: a base substrate; a gate electrode, an active layer, a source electrode and a drain electrode on the base substrate; and the thin film transistor further includes: a light-shielding portion between the active layer and the base substrate, the light-shielding portion includes a groove, and the active layer is in the groove.