Inorganic Interlayer Insulating Layer for Display Light Leak Reduction

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Solution Overview

Problem

In display devices with active matrix substrates, the use of thick organic insulating layers leads to deep contact holes that disrupt liquid crystal alignment, causing light leaks and reducing light utilization efficiency due to the need for large light-blocking regions to compensate for alignment errors.

Innovation Solution

A semiconductor device with a thin film transistor (TFT) substrate that employs an inorganic interlayer insulating layer without an organic layer, featuring a contact hole design that overlaps the oxide semiconductor layer and drain electrode, allowing for a transparent conductive layer to connect the pixel and drain electrodes directly, thereby reducing the area affected by light-blocking and enhancing alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a thick organic insulating layer is used to reduce parasitic capacitance and improve numerical aperture, then light utilization efficiency deteriorates due to deep contact holes causing light leaks and requiring large light-blocking regions

Engineering Contradiction:

Improvenumerical apertureVSAvoidlight utilization efficiency

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent changes the material parameter of the interlayer insulating layer from organic to inorganic material. This parameter change allows the insulating layer to achieve the required insulation performance with a thinner thickness, thereby reducing contact hole depth and eliminating light leaks without requiring large light-blocking regions, thus resolving the contradiction between numerical aperture improvement and light utilization efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the conventional thick organic insulating layer with a thin inorganic insulating layer. This substitution uses a different material system that achieves the same functional requirement (insulation) with significantly reduced thickness, eliminating the need for deep contact holes and associated light-blocking structures

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If the contact hole is made deep to connect drain electrode and pixel electrode through thick organic insulating layer, then parasitic capacitance is reduced, but light leak increases due to disturbed liquid crystal alignment

Engineering Contradiction:

Improveparasitic capacitance controlVSAvoidlight leak

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material parameter of the insulating layer from organic to inorganic, which fundamentally alters the thickness parameter. This parameter change reduces the insulating layer thickness from micrometer scale to sub-micrometer scale, thereby reducing contact hole depth and eliminating light leaks while maintaining adequate insulation performance for parasitic capacitance control

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If a light-blocking region is formed to shield the contact hole area, then light leak is suppressed, but the area contributing to display decreases, reducing light utilization efficiency

Engineering Contradiction:

Improvelight leak suppressionVSAvoidlight utilization efficiency

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The patent extracts the problematic deep contact hole structure by using a thin inorganic insulating layer instead of a thick organic one. This extraction eliminates the root cause of light leaks, making light-blocking regions unnecessary and thereby preserving the display area and light utilization efficiency

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the potential harm of thin insulating layers (insufficient insulation) into a benefit by selecting inorganic materials with superior dielectric properties. This allows the insulating layer to be thin enough to prevent light leaks while maintaining adequate insulation performance

Inventive Principle:

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

Data Source

PatentUS9583510B2Semiconductor device, display device, and method for manufacturing semiconductor device

Publication Date: 2017.02.28 SHARP KK

AI summary

A semiconductor device (100A) includes a first metal layer (12) including a gate electrode (12g); a gate insulating layer (14) formed on the first metal layer; an oxide semiconductor layer (16) formed on the gate insulating layer; a second metal layer (18) formed on the oxide semiconductor layer; an interlayer insulating layer (22) formed on the second metal layer; and a transparent electrode layer (TE) including a transparent conductive layer (Tc). The oxide semiconductor layer includes a first portion (16a) and a second portion (16b) extending while crossing an edge of the gate electrode. The second metal layer includes a source electrode (18s) and a drain electrode (18d). The interlayer insulating layer does not include an organic insulating layer. The interlayer insulating layer includes a contact hole (22a) formed so as to overlap the second portion and an end of the drain electrode that is closer to the second portion. The transparent conductive layer (Tc) is in contact with the end of the drain electrode and the second portion of the oxide semiconductor layer in the contact hole.