Oxide Semiconductor Layer Stack for Photodegradation Suppression
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Solution Overview
Problem
Semiconductor devices using oxide semiconductor films are prone to photodegradation due to the transparency of these films in the visible light region, which can affect their performance and reliability.
Innovation Solution
The semiconductor device incorporates a light shielding layer and a specific thickness of silicon nitride insulating layers to minimize light interference and reduce photodegradation. The thickness of the first silicon nitride insulating layer is adjusted to ensure that light reflected at the first and second interfaces weakens each other when incident at a specific angle, thereby suppressing photodegradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide semiconductor film is used as a channel, then the field effect mobility is improved and the fabrication process is simplified, but the device becomes susceptible to photodegradation due to light transparency
Solution Approach 1:
A light shielding layer is introduced as an intermediary component between the oxide semiconductor channel and the incident light. This layer blocks harmful visible light from reaching the channel, preventing photodegradation while allowing the oxide semiconductor to maintain its high mobility advantages
Solution Approach 2:
The device structure combines multiple materials with different optical properties - the oxide semiconductor channel layer is paired with light shielding layers and insulating layers having appropriate optical characteristics. This composite structure achieves both electrical performance and optical protection
2Stability of the object's composition
If a light shielding layer is added to prevent photodegradation, then photostability is improved, but the device structure becomes more complex
Solution Approach 1:
The light shielding layer is integrated into the existing device architecture, serving multiple functions: blocking incident light to prevent photodegradation, providing structural support, and maintaining electrical isolation. This multi-functionality reduces the need for additional dedicated components
Solution Approach 2:
The light shielding function is merged with the insulating layer structure. The silicon nitride insulating layer simultaneously provides electrical insulation and light shielding capabilities, combining protective functions that would otherwise require separate components
3Object-affected harmful factors
If the silicon nitride layer thickness is optimized for light interference suppression, then photodegradation is reduced, but the manufacturing precision requirement increases
Solution Approach 1:
The thickness of the silicon nitride layer is precisely controlled within a specific range (50-200 nm) to achieve destructive interference of reflected light waves. By optimizing this physical parameter, the structure suppresses photodegradation through optical interference while maintaining manufacturability
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 effectively suppresses photodegradation in oxide semiconductor devices, enhancing their stability and performance by minimizing the adverse effects of light interference.
Implementation Method 1
first light reflected at the first interface and second light reflected at the second interface weaken each other
Implementation Method 2
first light reflected at the first interface and second light reflected at the second interface weaken each other when light having a wavelength of 450 nm is incident
Data Source
AI summary
A semiconductor device includes a light shielding layer, a first silicon nitride insulating layer in contact with the light shielding layer with a first interface, a first silicon oxide insulating layer in contact with the first silicon nitride layer with a second interface, and an oxide semiconductor layer over the first silicon oxide insulating layer. The first silicon oxide insulating layer is in contact with the second silicon oxide insulating layer. A thickness t of the first silicon nitride layer satisfies a condition in which light reflected at the first interface and light reflected at the second interface weaken each other when light having a wavelength of 450 nm is incident on the first silicon nitride insulating layer at an angle of 60 degrees from a normal direction of the second interface.