Thin Film Transistor Passivation Layer Plasma Damage Protection
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Solution Overview
Problem
Compound semiconductor thin film transistors are prone to damage during the formation and patterning of passivation layers, leading to degradation of electrical properties due to plasma exposure, which affects the threshold voltage and overall performance.
Innovation Solution
A passivation layer made of inorganic oxide with a band gap equal or below 3.37eV is used, comprising elements from the compound semiconductor oxide, which acts as an etch stop layer and can restore the activation layer through annealing, preventing contamination and damage during the formation of source and drain electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a compound semiconductor activation layer is used, then manufacturing temperature can be reduced below 350°C and ion implantation can be omitted, but the activation layer becomes vulnerable to plasma damage during passivation layer formation
Solution Approach 1:
The patent applies preliminary action by forming the passivation layer of inorganic oxide before the activation layer is exposed to plasma damage. The passivation layer acts as a protective barrier that prevents plasma from directly contacting and damaging the compound semiconductor activation layer during subsequent processing steps.
Solution Approach 2:
The passivation layer serves as an intermediary between the plasma environment and the activation layer. This intermediate layer absorbs or deflects the harmful plasma effects, protecting the sensitive compound semiconductor material while allowing the manufacturing process to continue at low temperatures.
2Reliability
If the activation layer is damaged by plasma, then the threshold voltage changes and electrical properties deteriorate, but adding compensation circuits increases device complexity
Solution Approach 1:
The patent extracts the compensation function from the electrical circuit domain and relocates it to the material structure domain. Instead of adding compensation circuits to correct threshold voltage variations, the solution embeds protective functionality directly into the passivation layer structure, eliminating the need for external compensation mechanisms.
Solution Approach 2:
The patent replaces the electrical compensation system with a physical protection system. The passivation layer provides mechanical and chemical protection against plasma damage, substituting the need for complex electrical compensation circuits with a simpler structural solution.
3Ease of manufacture
If conventional passivation materials are used, then the manufacturing process is simpler, but they cannot effectively protect the activation layer from plasma damage
Solution Approach 1:
The patent changes the material parameter of the passivation layer by selecting inorganic oxide materials with specific properties (band gap equal or below 3.37eV). This parameter change enables the passivation layer to effectively absorb external light and resist plasma damage while maintaining compatibility with existing manufacturing processes.
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 solution effectively protects the activation layer from plasma damage, maintaining stable electrical properties over time and improving the reliability of the thin film transistor by absorbing external light efficiently and reducing the need for additional compensation processes.
Implementation Method 1
forming a passivation layer of an inorganic oxide which has a band gap equal or below 3.37eV, preferably equal or below 3eV adapted to absorb external light
Implementation Method 2
The passivation layer enables the activation layer to be restored through a subsequent annealing process
Data Source
Figure 1~2B
Figure 2C~2D
Figure 3A~3B
AI summary
A thin film transistor, a method of manufacturing the thin film transistor, and a flat panel display device including the thin film transistor. The thin film transistor includes: a gate electrode formed on a substrate; a gate insulating film formed on the gate electrode; an activation layer formed on the gate insulating film; a passivation layer including a compound semiconductor oxide, formed on the activation layer; and source and drain electrodes that contact the activation layer.