Display Panel TFT Ohmic Contact Layers to Prevent Etch 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 of display panels reduces the stability and uniformity of the display panels due to uneven distribution and material corrosion, leading to issues like uneven brightness and insulation layer cracking.
Innovation Solution
A manufacturing method involving specific flow rates and thicknesses for forming sub-ohmic contact layers, combined with controlled etching processes using chlorine and sulfur hexafluoride gases, to minimize the formation of abnormal protrusions by adjusting the ohmic contact layer thickness and doping concentrations, thereby improving the stability and uniformity of the display panels.
Engineering Contradictions & Design Principles
Engineering 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
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.
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.
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
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.
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.
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
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.
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 effectively reduces abnormal protrusions, enhancing the stability and uniformity of thin film transistors and display panels by minimizing contact resistance and etching residue, thus improving display performance.
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
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
Data Source
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.