Gate Insulator Composition for Reliable Display Transistors
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Solution Overview
Problem
Display devices experience image quality degradation due to transistor degradation, leading to issues like instantaneous afterimages, which existing techniques have not adequately addressed.
Innovation Solution
A transistor structure is developed with a gate insulating film having different component concentrations in its portions to remove traps at the interface between the active layer and the gate insulating film, improving both positive and negative degradation directions, and a manufacturing method is provided to form this structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing transistor structures and manufacturing techniques are used, then manufacturing process is simple, but transistor degradation occurs leading to image quality degradation and instantaneous afterimages
Solution Approach 1:
The gate insulating film is divided into multiple layers with different compositions and functions. The first gate insulating film layer is formed closer to the active layer while the second gate insulating film layer is formed closer to the gate electrode, with each layer having distinct component concentrations to address different degradation mechanisms separately
Solution Approach 2:
Different regions of the gate insulating film structure are assigned different material compositions optimized for their specific locations. The first portion (near active layer) has higher hydrogen concentration to remove traps, while the second portion (near gate electrode) has different composition to prevent degradation, creating local optimization throughout the structure
2Reliability
If uniform gate insulating film is used, then manufacturing process is simple, but traps at the interface between active layer and gate insulating film cause degradation
Solution Approach 1:
The component concentration of hydrogen and other elements is varied through the gate insulating film structure. The first portion has higher hydrogen concentration (e.g., 10-30 at%) to remove traps at the active layer interface, while the second portion has lower hydrogen concentration, creating a gradient that addresses degradation without requiring ultra-precise uniform deposition
Solution Approach 2:
The gate insulating film is constructed as a composite structure with at least two different insulating materials or compositions. This composite approach allows each layer to contribute different properties - one layer optimized for trap removal and another for stable electrical characteristics - achieving superior reliability through material combination rather than uniform composition
3Reliability
If single-component gate insulating film is used, then manufacturing is easier, but bidirectional degradation (positive and negative) cannot be prevented
Solution Approach 1:
The gate insulating film formation process is segmented into multiple deposition steps, with each step forming a specific layer with controlled composition. This multi-step process enables prevention of both positive bias temperature stress degradation and negative bias temperature stress degradation by assigning different functional compositions to different layers
Solution Approach 2:
The multi-layer gate insulating film structure performs multiple functions simultaneously: the first layer removes traps and prevents positive degradation, while the second layer provides stable electrical characteristics and prevents negative degradation. This multi-functional design achieves comprehensive degradation protection through a single integrated structure
Data Source
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AI summary
Disclosed are a display device and a manufacturing method thereof. More particularly, a display device including a substrate, a buffer layer disposed on the substrate, an active layer disposed on the buffer layer, a gate insulating film disposed on the active layer, and a gate electrode disposed on the gate insulating film, wherein the gate insulating film includes a first portion and a second portion, wherein the first portion is closer to the active layer than the second portion and the second portion is closer to the gate electrode than the first portion, and the gate insulating film includes two or more elements having different component concentrations in the first portion and the second portion, and a manufacturing method thereof are provided to provide a transistor structure having high reliability.