Oxide Semiconductor TFT Threshold Adjustment via Oxidation

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Solution Overview

Problem

There is no known method for adjusting the threshold value of thin-film transistors (TFTs) using oxide semiconductors in the channel layer, unlike TFTs with polycrystalline silicon, which limits the flexibility and performance of oxide semiconductor-based TFTs in display devices.

Innovation Solution

A method is developed to fabricate a thin-film transistor substrate by forming an oxide semiconductor layer, followed by a first oxide film and then a second oxide film, with controlled oxidation treatment parameters to adjust the threshold value of the TFT, allowing for precise setting of the threshold value based on predetermined relationships.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If oxide semiconductor is used in the channel layer of TFT, then low temperature process and high carrier mobility are achieved, but the threshold value cannot be adjusted

Engineering Contradiction:

Improvelow temperature processVSAvoidthreshold value adjustment

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by controlling oxidation treatment conditions (temperature, time, atmosphere) to adjust the oxygen concentration in the oxide semiconductor channel layer. By varying these oxidation parameters, the threshold value of the TFT can be precisely controlled without changing the fundamental material composition or requiring high temperature processing, thus maintaining ease of manufacture while achieving threshold value adaptability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material structure consisting of oxide semiconductor layer combined with oxide insulating layers. The oxide semiconductor channel layer is formed with specific composition (e.g., In-Ga-Zn-O) and through oxidation treatment creates a composite system where the oxygen concentration can be controlled to adjust electrical characteristics, enabling threshold value control while maintaining low temperature fabrication process.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If oxidation treatment is performed on oxide semiconductor layer, then threshold value can be adjusted, but process complexity increases

Engineering Contradiction:

Improvethreshold value adjustmentVSAvoidoxidation treatment process

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The oxidation treatment process serves multiple functions simultaneously: it adjusts the threshold value of the TFT, improves the electrical characteristics of the oxide semiconductor layer, and can be integrated into existing fabrication processes. By using a single oxidation step that achieves multiple objectives, the patent minimizes process complexity while providing threshold value control.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If multiple oxide films are formed with controlled oxidation, then precise threshold value control is achieved, but manufacturing steps increase

Engineering Contradiction:

Improvethreshold value precisionVSAvoidfabrication speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent merges multiple fabrication steps into integrated processes where oxide films are formed and oxidation treatment is combined with subsequent processing steps. By consolidating the formation of oxide semiconductor layer, oxide insulating layers, and oxidation treatment into a coordinated sequence that can be performed in fewer discrete steps, the patent achieves precise threshold value control while minimizing the impact on overall fabrication speed.

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 method enables the adjustment of the threshold value of oxide semiconductor-based TFTs to desired levels, improving their performance and flexibility in display devices like organic EL displays.

Implementation Method 1

performing an oxidation treatment on the oxide semiconductor layer

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS9484442B2Method of fabricating thin-film transistor substrate

Publication Date: 2016.11.01 MAGNOLIA BLUE CORP

AI summary

A method of fabricating a TFT substrate in which a thin-film transistor is formed on a substrate, includes: forming an oxide semiconductor layer above the substrate; forming a first oxide film on the oxide semiconductor layer; performing an oxidation treatment on the oxide semiconductor layer, after the first oxide film is formed; and forming a second oxide film above the first oxide film, after the oxidation treatment is performed. In the performing of the oxidation treatment, at least one parameter of the oxidation treatment is set, based on a predetermined relationship between the at least one parameter and the threshold value of the thin-film transistor, so that the threshold value becomes a predetermined value.