Array Substrate Protective Layer Deposition for TFT Mobility Stability

Solution Overview

Problem

The manufacturing method of SiNx film in existing technologies results in poor surface flatness and uniformity, leading to deteriorated field-effect mobility of Thin Film Transistor (TFT) in LCDs, affecting the display quality of TFT-LCD products.

Innovation Solution

The method involves depositing a protective layer on the gate layer using atomic layer deposition, which forms a uniform protective layer that reduces the impact on field-effect mobility, improving the stability and display effect of the TFT-LCDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If PECVD method is used to deposit SiNx film, then deposition speed is fast and process temperature is low, but surface flatness and uniformity deteriorate

Engineering Contradiction:

Improvedeposition speedVSAvoidsurface flatness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the deposition method from PECVD to ALD, fundamentally altering the deposition parameters and mechanism. ALD operates at lower temperatures (200-400°C) compared to PECVD, and uses sequential surface reactions with precursors to achieve atomic-level control over film growth, resulting in superior surface flatness and uniformity while maintaining reasonable deposition rates

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the plasma-enhanced chemical vapor deposition mechanism with an atomic layer deposition mechanism. ALD uses alternating exposure to precursor gases that react sequentially on the substrate surface, forming monolayers in a controlled manner, whereas PECVD relies on plasma activation and simultaneous chemical reactions, which lead to less controlled film growth and poorer surface quality

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If PECVD method is used to deposit SiNx film, then process temperature is low, but surface uniformity deteriorates

Engineering Contradiction:

Improveprocess temperatureVSAvoidsurface uniformity

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent changes the deposition method from PECVD to ALD, fundamentally altering the deposition parameters and mechanism. ALD operates at lower temperatures (200-400°C) compared to PECVD, and uses sequential surface reactions with precursors to achieve atomic-level control over film growth, resulting in superior surface flatness and uniformity while maintaining reasonable deposition rates

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the plasma-enhanced chemical vapor deposition mechanism with an atomic layer deposition mechanism. ALD uses alternating exposure to precursor gases that react sequentially on the substrate surface, forming monolayers in a controlled manner, whereas PECVD relies on plasma activation and simultaneous chemical reactions, which lead to less controlled film growth and poorer surface quality

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If plasma treatment is used to improve defects, then defect reduction is achieved, but ion damage is induced

Engineering Contradiction:

Improvedefect reductionVSAvoidion damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful plasma treatment process into a beneficial deposition process. Instead of using plasma to treat and potentially damage the SiNx film, the invention uses ALD to deposit the SiNx film in the first place, with the ALD process inherently producing high-quality, low-defect films without the need for subsequent plasma treatment, thus eliminating ion damage while maintaining defect reduction

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent performs the film deposition with high quality control in advance, using ALD to create a uniform, low-defect SiNx film from the beginning. This preliminary high-quality deposition eliminates the need for subsequent plasma treatment to reduce defects, thereby preventing ion damage before it can occur

Inventive Principle:

Principle #10Preliminary action

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 uniform protective layer deposited by atomic layer deposition enhances the field-effect mobility of TFTs, stabilizes the display, and improves the overall display effect by reducing surface defects and interface state density.

Implementation Method 1

depositing a protective layer on the substrate covered with the gate layer by atomic layer deposition

Methodology Applied

Scientific EffectAtomic layer deposition: Chemical Vapour Deposition

Data Source

PatentUS11749693B2Manufacturing method of array substrate, array substrate and display device

Publication Date: 2023.09.05 BEIHAI HKC OPTOELECTRONICS TECH CO LTD

AI summary

Disclosed are a manufacturing method of an array substrate, an array substrate and a display device. The manufacturing method of the array substrate includes: providing a substrate; depositing and patterning a gate layer on the substrate; depositing a protective layer on the substrate covered with the gate layer by atomic layer deposition; and depositing and patterning an amorphous silicon layer and an ohmic contact layer on the protective layer. The uniform protective layer of the present disclosure reduces the influence on the field effect mobility of the thin film transistor, makes the display of the product more stable, and improves the display effect.