Oxide Semiconductor Carrier Control via Halogen Plasma
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Solution Overview
Problem
Current methods for manufacturing semiconductor devices with oxide semiconductors face challenges such as high carrier concentrations leading to normally-on devices and significant characteristic variations, primarily due to hydrogen and oxygen deficiencies.
Innovation Solution
Incorporating a cation containing oxygen or halogen into the oxide semiconductor layer or insulating layers to reduce carrier concentrations and stabilize the semiconductor characteristics, using plasma treatments like ECR, HWP, or ICP to minimize hydrogen incorporation and enhance the semiconductor's intrinsic nature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to manufacture oxide semiconductor devices, then manufacturing simplicity is maintained, but high carrier concentrations occur leading to normally-on devices and large characteristic variations
Solution Approach 1:
The patent applies preliminary action by performing plasma treatment on the oxide semiconductor layer before subsequent processing steps. This pre-treatment reduces carrier concentration and prevents normally-on characteristics, establishing stable device properties early in the manufacturing process. The plasma treatment is conducted prior to electrode formation and other critical steps, ensuring that the semiconductor layer is properly prepared to avoid later defects.
Solution Approach 2:
The patent changes physical and chemical parameters of the oxide semiconductor layer through plasma treatment. Specifically, it modifies the carrier concentration, oxygen content, and hydrogen content by exposing the layer to plasma containing oxygen or halogen. These parameter changes transform the semiconductor from a high-carrier-state (normally-on) to a low-carrier-state (normally-off), resolving the reliability issue while maintaining manufacturing feasibility.
2Reliability
If plasma treatment with oxygen or halogen is applied to reduce carrier concentration, then normally-off characteristics are achieved, but manufacturing process complexity increases
Solution Approach 1:
The patent utilizes parameter changes by controlling plasma treatment conditions such as gas composition (oxygen or halogen), power, pressure, and treatment duration. By optimizing these parameters, the process achieves effective carrier concentration reduction while minimizing process complexity. The treatment transforms the oxide semiconductor from high-carrier to low-carrier state, enabling normally-off characteristics without requiring fundamentally new manufacturing approaches.
Solution Approach 2:
The patent employs plasma containing oxygen or halogen as strong oxidizing agents. These oxidants react with the oxide semiconductor layer to reduce carrier concentration by removing excess electrons and stabilizing the oxygen content. This accelerated oxidation process through plasma is more effective than thermal oxidation alone, achieving the desired normally-off characteristics while maintaining reasonable manufacturing simplicity.
3Ease of manufacture
If hydrogen is incorporated in the oxide semiconductor layer, then manufacturing is simpler, but carrier concentration increases causing normally-on behavior
Solution Approach 1:
The patent applies preliminary anti-action by performing plasma treatment with oxygen or halogen before subsequent processing steps that might introduce hydrogen. This pre-treatment establishes a low-carrier state and creates a protective condition that resists hydrogen incorporation. By acting in advance against potential hydrogen contamination, the process maintains normally-off characteristics while allowing for simpler subsequent manufacturing steps.
Solution Approach 2:
The patent uses plasma containing oxygen or halogen as strong oxidants to counteract hydrogen incorporation. The oxidizing plasma removes hydrogen from the oxide semiconductor layer and prevents its incorporation during manufacturing. This chemical counter-action effectively controls carrier concentration by eliminating hydrogen-induced carriers, achieving normally-off behavior without compromising manufacturing simplicity.
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 approach enables the production of semiconductor devices with reduced characteristic variations and achieves normally-off field effect transistors, improving the reliability and stability of oxide semiconductor elements.
Implementation Method 1
adding a cation containing one or more elements selected from oxygen and halogen to the oxide semiconductor layer
Data Source
AI summary
An object of an embodiment of the present invention is to provide a semiconductor device including a normally-off oxide semiconductor element whose characteristic variation is small in the long term. A cation containing one or more elements selected from oxygen and halogen is added to an oxide semiconductor layer, thereby suppressing elimination of oxygen, reducing hydrogen, or suppressing movement of hydrogen. Accordingly, carriers in the oxide semiconductor can be reduced and the number of the carriers can be kept constant in the long term. As a result, the semiconductor device including the normally-off oxide semiconductor element whose characteristic variation is small in the long term can be provided.