Thin-Film Transistor Gate Electrode Stack for Flat, Conductive Films
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Solution Overview
Problem
The challenge lies in manufacturing thin film transistors with increased pixel density and performance requirements, where existing methods face issues with uniformity and productivity due to the deposition of multiple metal film layers, leading to uneven surfaces and decreased conductivity.
Innovation Solution
A manufacturing method involving the deposition of an aluminum film by physical vapor deposition followed by a molybdenum film using atomic layer deposition, with specific etching steps to form a gate electrode, and subsequent layers to create a thin film transistor, ensuring improved conductivity and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple metal film layers are deposited to improve conductivity and prevent diffusion, then film quality and performance are improved, but manufacturing time and process complexity increase
Solution Approach 1:
The gate electrode is segmented into multiple functional layers: aluminum film for high conductivity, molybdenum film for diffusion prevention, and tungsten film for mechanical strength. Each layer performs a specific function, allowing the system to achieve high reliability without requiring excessive thickness in any single layer, thus balancing performance with manufacturing efficiency.
Solution Approach 2:
The patent employs composite material structure by combining different metal films (aluminum, molybdenum, tungsten) with complementary properties. This composite approach leverages the high conductivity of aluminum, the diffusion barrier properties of molybdenum, and the mechanical strength of tungsten, achieving superior overall performance while maintaining reasonable deposition times through optimized layer thicknesses.
2Reliability
If aluminum film thickness is increased to improve conductivity, then electrical performance is improved, but surface flatness deteriorates
Solution Approach 1:
Instead of using a single thick aluminum layer, the conductive function is segmented across multiple thinner layers including aluminum film (50-200 nm), molybdenum film (10-50 nm), and tungsten film (10-50 nm). This segmentation maintains high conductivity through the composite structure while each thin layer deposits more uniformly, preserving surface flatness and preventing defects associated with thick single-layer deposition.
Solution Approach 2:
The composite metal film structure combines materials with different deposition characteristics. The aluminum layer provides conductivity, while the molybdenum and tungsten layers have excellent step coverage and surface smoothing properties during deposition. This composite approach achieves high conductivity without sacrificing surface flatness, as the thinner multi-material structure deposits more uniformly than a single thick aluminum layer.
3Manufacturing precision
If atomic layer deposition is used for molybdenum film to improve coverage and density, then film quality is improved, but deposition time increases
Solution Approach 1:
The molybdenum film is deposited as a thin layer (10-50 nm) using atomic layer deposition, providing excellent uniformity and step coverage. This thin segmented layer is then combined with faster-deposited aluminum and tungsten layers. The segmentation allows ALD to be applied only where its superior uniformity is most beneficial, while other layers use faster deposition methods, balancing film quality with overall deposition speed.
Solution Approach 2:
The composite gate electrode structure incorporates a thin ALD-deposited molybdenum layer for superior uniformity and diffusion barrier properties, combined with PVD-deposited aluminum and tungsten layers for high conductivity and mechanical strength. This composite approach uses ALD selectively for the critical barrier layer where uniformity is paramount, while using faster PVD methods for layers where thickness and conductivity are more critical, thus optimizing both film quality and deposition efficiency.
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 results in a thin film transistor with enhanced electron mobility, conductivity, and productivity, addressing the issues of uniformity and surface flatness, while preventing aluminum diffusion and maintaining high film quality.
Implementation Method 1
depositing an aluminum film on a substratum by physical vapor deposition
Implementation Method 2
depositing a molybdenum film over the aluminum film by atomic layer deposition
Implementation Method 3
etching the aluminum film and the molybdenum film to form the gate electrode of a predetermined pattern
Data Source
AI summary
The present application discloses a manufacturing method for a gate electrode and a thin film transistor, and a display panel, including: depositing an aluminum film on a substratum by physical vapor deposition; depositing a molybdenum film over the aluminum film by atomic layer deposition; and etching the aluminum film and the molybdenum film to form the gate electrode of a predetermined pattern.