Oxide Semiconductor Device Hydrogen Barrier Structure
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Solution Overview
Problem
The existing semiconductor devices face challenges in preventing the entry of hydrogen-containing substances into oxide semiconductor layers, which shifts the threshold voltage of transistors and affects the on-current, and there is a need for a novel structure that effectively utilizes conductive layers formed in the same process as electrodes.
Innovation Solution
The semiconductor device structure includes multiple conductive layers and insulating layers, with specific overlapping areas and configurations to prevent hydrogen element entry into the oxide semiconductor layer, while allowing effective use of conductive layers as electrodes, and enhancing the on-current of transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conductive layer is formed in the same process as an electrode, then manufacturing efficiency is improved, but the conductive layer may contain hydrogen-containing substances that shift the threshold voltage of transistors
Solution Approach 1:
The patent divides the protective function into multiple segments: a first protective film formed before the conductive layer, and a second protective film formed after the conductive layer. This segmentation allows the conductive layer to be formed in the same process as the electrode while maintaining threshold voltage stability through the combined protection of both films.
Solution Approach 2:
The first protective film is formed in advance before the conductive layer is deposited. This preliminary protective layer prevents hydrogen-containing substances from the conductive layer formation process from entering the oxide semiconductor layer, thereby maintaining threshold voltage stability while allowing efficient manufacturing.
2Reliability
If multiple protective films are added to prevent hydrogen entry, then threshold voltage stability is improved, but device structure complexity increases
Solution Approach 1:
The first and second protective films serve multiple functions: they act as barriers against hydrogen-containing substances, provide structural support, and can be integrated with existing device layers. This multi-functionality justifies the added structural elements while maintaining manufacturing efficiency.
3Productivity
If the conductive layer is used as both electrode and protective layer, then manufacturing steps are reduced, but the on-current of transistors decreases
Solution Approach 1:
The patent segments the protective function from the electrode function by using separate first and second protective films, allowing the conductive layer to be optimized for electrode performance while the protective films maintain transistor performance by preventing hydrogen entry.
Data Source
AI summary
A semiconductor device includes a first conductive layer, a first insulating layer over the first conductive layer, first and second oxide semiconductor layers over the first insulating layer, a second conductive layer over the first oxide semiconductor layer, a third conductive layer over the second oxide semiconductor layer, a fourth conductive layer over the first oxide semiconductor layer and the second oxide semiconductor layer, a second insulating layer over the second conductive layer, the third conductive layer, and the fourth conductive layer, a fifth conductive layer electrically connected to the first conductive layer over the second insulating layer, and a sixth conductive layer over the second insulating layer. Each of the first and fifth conductive layers includes an area overlapping with the first oxide semiconductor layer. The sixth conductive layer includes an area overlapping with the second oxide semiconductor layer.