Gate Insulator Sidewall Geometry to Prevent Display TFT Short-Circuits

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Solution Overview

Problem

In organic light-emitting display devices, a short-circuit can occur between the gate electrode and the semiconductor layer due to ion sputtering during the etching process of the gate insulator, and there is a need to reduce the step height of the gate insulator and gate electrode.

Innovation Solution

A display device structure is implemented with a gate insulator having a side surface featuring a first inclined portion with a gentle inclination and a second inclined portion with a steep inclination, preventing ion sputtering from the semiconductor layer and reducing the step height by adjusting the angles of the gate electrode and insulator surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the gate insulator is etched between the gate electrode and the semiconductor layer, then the gate electrode and semiconductor layer can be electrically isolated, but ions of the semiconductor layer may sputter on the side surface of the gate insulator causing short-circuits

Engineering Contradiction:

Improveelectrical isolation between gate electrode and semiconductor layerVSAvoidion sputtering of semiconductor layer on gate insulator side surface

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The gate insulator side surface is designed with inclined portions having specific angle ranges (first inclined portion: 30-60 degrees, second inclined portion: 60-85 degrees) instead of vertical surfaces. This curved/angled geometry prevents ion sputtering from adhering to the gate insulator side surface, thereby eliminating the short-circuit problem while maintaining electrical isolation.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The gate insulator is formed as a composite structure with multiple layers (first gate insulator layer and second gate insulator layer) having different materials and properties. This layered composite structure allows optimization of each layer's function - one layer provides electrical isolation while the other protects against ion sputtering, resolving the contradiction between isolation and sputtering prevention.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If the gate insulator has vertical sides, then the structure is simple, but it creates large step height that complicates subsequent processing

Engineering Contradiction:

Improvegate insulator structure simplicityVSAvoidstep height of gate insulator

Core Design Contradiction:

Device complexityVSShape

Solution Approach 1:

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The gate insulator structure parameters are optimized by controlling the etching process to create inclined portions with specific angle ranges. The first inclined portion has an angle of 30-60 degrees and the second inclined portion has an angle of 60-85 degrees. This parameter optimization reduces step height while maintaining structural integrity and simplifying subsequent processing.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If the gate insulator side surface is inclined at small angles, then ion sputtering is prevented, but the etching process becomes more difficult

Engineering Contradiction:

Improveion sputtering preventionVSAvoidetching process difficulty

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The gate insulator side surface is divided into multiple segments: a first inclined portion with a gentler angle (30-60 degrees) and a second inclined portion with a steeper angle (60-85 degrees). This segmentation allows the etching process to create different angles in different regions, preventing ion sputtering on the first inclined portion while making the etching process more controllable and easier to manufacture compared to creating a single uniform shallow angle throughout.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the gate insulator side surface have different local properties - the first inclined portion has a gentler angle (30-60 degrees) optimized for preventing ion sputtering, while the second inclined portion has a steeper angle (60-85 degrees) optimized for etching controllability. This local quality differentiation resolves the contradiction between sputtering prevention and manufacturing ease.

Inventive Principle:

Principle #3Local quality

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 structure effectively prevents short-circuits between the semiconductor layer and the gate electrode while reducing the step height, enhancing the reliability and manufacturing efficiency of the display device.

Implementation Method 1

prevent the problem that a short-circuit is formed between a gate electrode and a semiconductor layer due to sputtering of ions of the semiconductor layer on a side surface of a gate insulator during the process of etching the gate insulator

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS20230397477A1Display device

Publication Date: 2023.12.07 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a semiconductor layer on an opposite side to a light-blocking layer, the semiconductor layer including an active layer overlapping the light-blocking layer, a first gate insulator on an opposite side to a buffer film with the active layer therebetween, and a first gate electrode on an opposite side to the active layer with the first gate insulator therebetween, a side surface of the first gate insulator includes a first inclined portion contacting a first surface of the semiconductor layer, and a second inclined portion contacting the first inclined portion and the first gate electrode, and a first angle between the first surface of the semiconductor layer and the first inclined portion is less than a second angle between the first surface of the semiconductor layer and the second inclined portion.