Thin-Film Transistor Gate Wire Segmentation for Low Resistance
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Solution Overview
Problem
In thin-film transistor array devices for image display, high heat-resistant metals used for gate electrodes result in high wire resistance, leading to signal delays and display unevenness, while reducing gate insulating film thickness increases parasitic capacitance and metal oxidation, affecting performance.
Innovation Solution
The device employs a conductive oxide film and a relay electrode to separate the gate wire and source wire, using different materials for the gate electrode and wire to reduce resistance and prevent oxidation, with the conductive oxide film interposed between the relay electrode and current-supply electrode to prevent oxidation of the lower electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high heat-resistant metals are used for gate electrodes, then heat resistance is improved, but wire resistance increases causing signal delays and display unevenness
Solution Approach 1:
The gate electrode structure is segmented into two distinct parts: the gate electrode itself made of high heat-resistant metal (Mo, W, Ti, or Ta) and the gate wire made of low-resistance metal (Al or Cu). This segmentation allows each part to be optimized for its specific function - heat resistance at the electrode and low resistance for signal transmission in the wire.
Solution Approach 2:
Different materials with different properties are used in different locations of the gate structure. The gate electrode region uses high heat-resistant metals suitable for laser crystallization processes, while the gate wire region uses low-resistance metals optimized for electrical signal transmission. This local quality differentiation resolves the contradiction between heat resistance and electrical conductivity.
2Productivity
If gate insulating film thickness is reduced, then device performance is improved, but parasitic capacitance and metal oxidation increase
Solution Approach 1:
The gate insulating film is constructed as a composite structure with multiple layers having different functions. The first gate insulating film (e.g., SiO2 or Si3N4) provides electrical insulation, while the second gate insulating film (e.g., SiO2) serves as a protective barrier against metal oxidation. This composite structure allows thin film dimensions for high performance while preventing harmful oxidation effects.
3Ease of manufacture
If the same metal material is used for both gate electrode and gate wire, then manufacturing is simplified, but wire resistance becomes high causing signal delays
Solution Approach 1:
The gate structure is segmented into electrode and wire portions with different material compositions. The gate electrode uses high heat-resistant metal suitable for laser processing, while the gate wire uses low-resistance metal for optimal signal transmission. This segmentation prioritizes electrical performance over manufacturing simplicity.
Solution Approach 2:
The material parameter (metal type) is changed between the gate electrode and gate wire portions. By changing the material parameter from high heat-resistant metal in the electrode to low-resistance metal in the wire, the invention optimizes both heat resistance and electrical conductivity despite increased manufacturing complexity.
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 configuration achieves low resistance for the gate wire, reduces parasitic capacitance, and prevents metal oxidation, thereby improving signal transmission and maintaining high display quality without signal delays or image deterioration.
Implementation Method 1
the conductive oxide film interposed between the relay electrode and current-supply electrode to prevent oxidation of the lower electrode
Implementation Method 2
irradiating a laser beam onto a non-single crystal semiconductor thin-film of amorphous silicon or polycrystalline silicon formed on a low-heat-resistance insulation substrate such as glass so as to melt the semiconductor thin-film by localized heating
Implementation Method 3
melt the semiconductor thin-film by localized heating
Implementation Method 4
subsequently crystallizing the semiconductor thin-film in a cooling process thereof
Data Source
AI summary
A thin-film transistor array device includes a passivation film above first and second bottom gate transistors. A gate wire is below the passivation film. A source wire and a relay wire are above the passivation film. The source wire is electrically connected to a source electrode of the first transistor via a first hole in the passivation film. A conductive oxide film is between the passivation film and both the source wire and the relay electrode and not electrically connected between the source wire and the relay electrode. The conductive oxide film covers an end portion of the gate wire that is exposed via a second hole in the passivation film. The conductive oxide film is between the relay electrode and a current-supply electrode of the second transistor and electrically connects the relay electrode and the current-supply electrode via a third hole in the passivation film.