Gate Electrode Light-Shielding and Adhesion in Semiconductor Devices
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Solution Overview
Problem
Existing semiconductor devices and projection-type display units face issues with low light-shielding performance for light incident from the side on LDD regions and susceptibility to film detachment due to low adhesiveness between insulating and electroconductive films, as well as stress differences between films.
Innovation Solution
A semiconductor device with a gate electrode comprising a layered structure of a first electroconductive film and a second electroconductive film with light-shielding properties, where the second electroconductive film extends from the side face to the bottom face of openings interposing the semiconductor layer, enhancing adhesiveness with the gate insulating layer and improving light-shielding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer electroconductive film is used as the gate electrode, then the device complexity is reduced, but the light-shielding performance for oblique light incident on the LDD region is insufficient
Solution Approach 1:
The gate electrode is constructed as a composite structure with a first electroconductive film (highly conductive material such as aluminum or copper) and a second electroconductive film (light-shielding material such as tungsten or molybdenum). This composite structure simultaneously achieves high electrical conductivity and effective light-shielding performance, including protection against oblique light incident on the LDD region, by combining materials with complementary properties.
Solution Approach 2:
The second electroconductive film extends not only horizontally across the channel region but also vertically down the sidewalls of the gate insulating layer into the openings. This three-dimensional extension ensures that oblique light rays incident from various angles are blocked, providing comprehensive light-shielding coverage that a planar single-layer structure cannot achieve.
2Object-affected harmful factors
If an insulating film is added between the electroconductive film and the gate insulating layer to improve light-shielding, then the light-shielding performance is improved, but film detachment occurs due to low adhesiveness and stress difference
Solution Approach 1:
The second electroconductive film serves dual functions: it provides light-shielding properties and acts as an adhesive layer between the first electroconductive film and the gate insulating layer. Materials such as tungsten or molybdenum are selected not only for their light-shielding capabilities but also for their good adhesion to silicon oxide and stress-compatibility with surrounding films, eliminating the need for separate insulating adhesive layers and preventing film detachment.
3Object-affected harmful factors
If the second electroconductive film is extended to the bottom face of openings, then the light-shielding performance is improved, but the manufacturing precision requirement increases
Solution Approach 1:
The gate electrode structure is formed by first creating the first electroconductive film and gate insulating layer, then forming openings, and finally filling the openings with the second electroconductive film. This sequential formation process with preliminary preparation of the gate structure simplifies the overall manufacturing steps and reduces precision requirements compared to attempting to form a complex single-layer structure that would require precise patterning and alignment.
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 enhances light-shielding performance and resistance to film detachment, effectively suppressing oblique light incidence and preventing light leakage currents, leading to improved display quality and production yield in projection-type display units.
Implementation Method 1
the gate electrode includes a first electroconductive film and a second electroconductive film that has a light-shielding property in order from side of the semiconductor layer
Data Source
AI summary
A semiconductor device according to an embodiment of the disclosure includes: a first substrate; a TFT element provided on the first substrate with a first interlayer insulating layer interposed therebetween, and including a semiconductor layer and a gate electrode that is provided on the semiconductor layer with a gate insulating layer interposed therebetween; and a second substrate disposed to face the first substrate. The gate electrode includes a first electroconductive film and a second electroconductive film that has a light-shielding property in order from side of the semiconductor layer. The second electroconductive film extends from a side face to a bottom face of each of a pair of openings that are provided to interpose the semiconductor layer.