TFT Substrate Ohmic Contact via Plasma Activation
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Solution Overview
Problem
The existing manufacturing processes for organic light emitting display substrates with thin film transistors require ion doping, which is complex and costly, especially for large-sized panels, and lacks efficient conductivity in source and drain areas.
Innovation Solution
The substrate is manufactured without ion doping by using plasma enhanced chemical vapor deposition (PECVD) to form amorphous or multi-crystalline silicon layers with ion impurities, such as N+ or P+ impurities, and subsequent plasma processes with phosphorous-based or boron-based gases to achieve conductive ohmic contact layers and source/drain areas, eliminating the need for ion injecting processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion doping process is used to form ohmic contact layers, then conductivity in source and drain areas is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the ion doping process from the manufacturing sequence, replacing it with a plasma treatment step that achieves the same conductivity enhancement without requiring ion implantation equipment or complex doping parameters control
Solution Approach 2:
The patent changes the fundamental parameter of how conductivity is achieved - instead of introducing ion impurities through doping, it uses plasma activation to modify the existing material properties, thereby achieving ohmic contact through surface activation rather than bulk doping
2Reliability
If ion doping process is used to form ohmic contact layers, then conductivity in source and drain areas is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive ion doping equipment with standard plasma processing equipment that is already commonly available in display manufacturing lines, effectively using existing infrastructure rather than requiring specialized costly equipment
Solution Approach 2:
The plasma processing step serves multiple functions simultaneously - it activates the surface for ohmic contact formation, cleans the surface, and prepares it for subsequent electrode deposition, eliminating the need for separate dedicated doping equipment
3Ease of manufacture
If existing manufacturing processes are used, then thin film transistor substrate can be manufactured, but source and drain areas lack efficient conductivity
Solution Approach 1:
The patent performs plasma treatment on the source and drain areas before depositing the electrode materials, pre-activating the surface to ensure optimal conductivity and contact properties from the outset rather than attempting to correct conductivity issues after electrode formation
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 method simplifies the manufacturing process, reduces costs by avoiding expensive ion injection devices, and ensures high conductivity in the source and drain areas, enabling the production of large-sized organic light emitting display apparatuses with improved on-current performance.
Implementation Method 1
plasma enhanced chemical vapor deposition (PECVD) to form amorphous or multi-crystalline silicon layers with ion impurities
Implementation Method 2
subsequent plasma processes with phosphorous-based or boron-based gases to achieve conductive ohmic contact layers
Data Source
AI summary
A substrate including a thin film transistor, the substrate including an active layer disposed on the substrate, the active layer including a channel area and source and drain areas, a gate electrode disposed on the active layer, the channel area corresponding to the gate electrode, a gate insulating layer interposed between the active layer and the gate electrode, an interlayer insulating layer disposed to cover the active layer and the gate electrode, the interlayer insulating layer having first and second contact holes partially exposing the active layer, source and drain electrodes disposed on the interlayer insulating layer, the source and drain areas corresponding to the source and drain electrodes, and ohmic contact layers, the ohmic contact layers being interposed between the interlayer insulating layer and the source and drain electrodes, and contacting the source and drain areas through the first and second contact holes.