Display Panel Ohmic Contact Layer Etching to Prevent TFT Protrusions

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Solution Overview

Problem

The formation of abnormal protrusions on the semiconductor layer during the etching process in thin film transistors reduces the stability and uniformity of display panels, leading to uneven brightness and potential cracking of insulation layers.

Innovation Solution

A manufacturing method for display panels involving the formation of a semiconductor layer with specific sub-ohmic contact layers and controlled etching processes, including a volume flow rate of phosphine and chlorine, to remove part of the ohmic contact layer between the source and drain, thereby reducing abnormal protrusions and improving stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the source/drain metal layer is directly lap-jointed on the semiconductor layer, then the manufacturing process is simplified, but abnormal protrusions form on the semiconductor layer surface during etching, reducing stability and uniformity

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidsemiconductor layer surface uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The semiconductor layer is segmented into a semiconductor sub-layer and an ohmic contact layer formed by sublimation doping. This segmentation allows the etching process to selectively remove material from the ohmic contact layer without significantly affecting the semiconductor sub-layer, preventing abnormal protrusions while maintaining manufacturing simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The ohmic contact layer is formed in advance through sublimation doping before the etching process. This preliminary action creates a sacrificial layer that protects the underlying semiconductor sub-layer during etching, preventing the formation of abnormal protrusions on the semiconductor layer surface.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the semiconductor layer is etched to remove the ohmic contact layer between source and drain, then contact resistance is reduced, but abnormal protrusions form on the semiconductor layer surface

Engineering Contradiction:

Improvecontact resistanceVSAvoidsemiconductor layer surface uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The etching process is applied locally and selectively to remove only the ohmic contact layer material between the source and drain regions. The semiconductor sub-layer is protected from excessive etching due to its different material properties and the controlled etching parameters, maintaining surface uniformity while achieving low contact resistance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The semiconductor sub-layer acts as an intermediary protective layer during the etching process. It allows the etching to proceed through the ohmic contact layer to reduce contact resistance while protecting the underlying semiconductor structure from forming abnormal protrusions.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If high phosphine flow rate is used to form the ohmic contact layer, then doping concentration and electrical conductivity are improved, but manufacturing cost and process complexity increase

Engineering Contradiction:

Improveelectrical conductivityVSAvoidprocess control complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The phosphine flow rate is optimized within a specific range (6590-12590 sccm for the first sublimation, 21000-27000 sccm for the second sublimation) to achieve the desired doping concentration and electrical conductivity. This parameter optimization balances performance requirements with process control simplicity, avoiding excessive complexity while maintaining high electrical conductivity.

Inventive Principle:

Principle #35Parameter changes

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 method enhances the stability and uniformity of thin film transistors by minimizing abnormal protrusions, reducing contact resistance, and improving the overall performance of display panels.

Implementation Method 1

forming a first sub-ohmic contact layer on the semiconductor sub-layer, and forming a second sub-ohmic contact layer on the first sub-ohmic contact layer; a volume flow rate of phosphine for forming the first sub-ohmic contact layer may be greater than or equal to 6590 sccm and less than or equal to 12590 sccm

Methodology Applied

Scientific EffectSublimation doping:

Implementation Method 2

etching the semiconductor layer to remove a part of the ohmic contact layer disposed between the source and the drain, where a volume flow rate of chlorine in an etching gas for etching the semiconductor layer may be less than 400 sccm

Methodology Applied

Scientific EffectPlasma etching:

Data Source

PatentUS20240332307A1Manufacturing methods of display panels and display panels

Publication Date: 2024.10.03 TCL CHINA STAR OPTOELECTRONICS TECHNOLOGY CO LTD

AI summary

A manufacturing method of a display panel includes following steps: forming a semiconductor layer on a substrate, in which the semiconductor layer includes a semiconductor sub-layer and an ohmic contact layer including a first sub-ohmic contact layer and a second sub-ohmic contact layer, and a volume flow rate of phosphine for forming the first sub-ohmic contact layer is greater than or equal to 6590 sccm and less than or equal to 12590 sccm, and a volume flow rate of phosphine for forming the second sub-ohmic contact layer is greater than or equal to 21000 sccm and less than or equal to 27000 sccm.