Oxide Semiconductor Top Electrode for Thin Film Transistor Substrates

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Solution Overview

Problem

In the manufacturing of thin film transistor substrates for organic EL display devices, interlayer short-circuit defects in capacitors due to foreign matter in the insulating film lead to increased defects and reduced yield, particularly because the conductivity of amorphous silicon top electrodes is low, affecting the capacitor's functionality.

Innovation Solution

The use of an oxide semiconductor material for the top electrode in the capacitor, which has higher conductivity than amorphous silicon, reducing the occurrence of interlayer short-circuits and allowing the capacitor to function effectively even with foreign matter present.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If amorphous silicon is used for the top electrode in the capacitor, then the manufacturing process is simpler, but the conductivity is low causing interlayer short-circuit defects

Engineering Contradiction:

Improvecapacitor functionalityVSAvoidinterlayer short-circuit defect

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material parameter of the top electrode from amorphous silicon to oxide semiconductor, which fundamentally alters the conductivity parameter. This material substitution resolves the contradiction by providing both sufficient conductivity for capacitor functionality and resistance to interlayer short-circuit defects caused by foreign matter

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs oxide semiconductor as a composite material solution for the top electrode. This material combines the benefits of high conductivity similar to crystalline silicon with the manufacturing simplicity and defect tolerance of amorphous silicon, thereby resolving the contradiction between reliability and harmful factors

Inventive Principle:

Principle #40Composite materials

2Reliability

If amorphous silicon is used for the top electrode, then manufacturing is easier, but conductivity is insufficient affecting capacitor function

Engineering Contradiction:

Improvecapacitor functionalityVSAvoidtop electrode material deposition

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent accepts the use of oxide semiconductor which may require slightly more complex deposition processes but provides durable, high-performance capacitor electrodes that resist defects. The improved reliability compensates for any additional manufacturing complexity, achieving better long-term performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS8426862B2Thin film transistor substrate and display device

Publication Date: 2013.04.23 MAGNOLIA BLUE CORP

AI summary

A thin film transistor substrate with reduced interlayer short-circuit defects in a capacitor, and a display device having the thin film transistor substrate. The thin film transistor substrate includes: a substrate; a thin film transistor having, over the substrate, a gate electrode, a gate insulating film, an oxide semiconductor layer, and a source-drain electrode in order; and a capacitor having, over the substrate, a bottom electrode, a capacitor insulating film, and a top electrode made of oxide semiconductor in order.