IGZO TFT Oxygen Balance via Plasma-Treated Passivation
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Solution Overview
Problem
The existing fabrication process of back channel etching type oxide semiconductor TFT substrates, particularly those using Indium Gallium Zinc Oxide (IGZO), faces challenges in maintaining oxygen element balance in the superficial layer, leading to instability and increased leakage current due to damage from copper etching solutions like hydrogen peroxide-based ones, which affect the performance and reliability of the TFT devices.
Innovation Solution
A method involving the use of a silicon oxide first passivation layer treated with nitrous oxide plasma to infiltrate oxygen elements into the superficial layer of the IGZO channel region, ensuring oxygen balance while preventing excessive oxidation of the source and drain areas, thereby stabilizing the TFT substrate during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If copper etching solution (hydrogen peroxide-based) is used to fabricate source and drain, then the etching process can be completed, but the oxygen element balance in the superficial layer of IGZO channel region is damaged, leading to increased leakage current and instability
Solution Approach 1:
The patent applies preliminary action by forming a protective silicon oxide layer on the IGZO surface before the copper etching process. This protective layer is prepared in advance to prevent oxygen loss during subsequent etching, thereby maintaining oxygen balance and preventing leakage current increase while allowing the etching process to proceed normally
2Device complexity
If the etch stop layer is removed to simplify the fabrication process, then the number of lithography processes is reduced, but the IGZO active layer becomes vulnerable to damage from etching solutions
Solution Approach 1:
The patent introduces an intermediary protective silicon oxide layer that acts as a mediator between the IGZO active layer and the copper etching solution. This intermediary layer shields the IGZO from direct contact with harmful etching chemicals while allowing the simplified fabrication process to proceed, thus reducing both device complexity and etching damage simultaneously
3Ease of manufacture
If the superficial layer of IGZO is exposed during etching, then the source and drain can be formed, but oxygen elements are lost, affecting the oxygen element balance and increasing leakage current
Solution Approach 1:
The protective silicon oxide layer is formed preliminarily before source and drain formation to prevent oxygen loss during the exposure and etching processes. This preliminary protection ensures that oxygen element balance is maintained while still allowing source and drain to be formed successfully
4Device complexity
If no protective layer is used during etching, then the fabrication process is simpler, but the active layer suffers from oxygen loss and surface characteristic changes
Solution Approach 1:
The protective silicon oxide layer serves as an intermediary that minimally increases fabrication complexity while effectively preventing oxygen loss and surface characteristic changes. The added step is justified by the significant improvement in manufacturing precision and device performance
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 ensures the oxygen element balance in the superficial layer of the IGZO TFT substrate, enhancing its stability and reducing leakage current, while minimizing damage to the active layer, thus improving the overall performance and reliability of the TFT devices.
Implementation Method 1
treating a surface of the first passivation layer by an oxygen element containing plasma, infiltrating traces of oxygen element into a superficial layer of the channel region of the active layer via the first passivation layer
Data Source
AI summary
The present application provides a method for fabricating a back channel etching oxide semiconductor TFT substrate, by depositing the first passivation layer on the source, the drain and the active layer, and treating the oxygen element containing plasma to a surface of the first passivation layer, infiltrating traces of oxygen element into the superficial layer of the channel region of the active layer through the first passivation layer, then using an oxygen element containing plasma to treat the surface of the first passivation layer, so that the traces of oxygen element infiltrates into the superficial layer of the channel region of the active layer via the first passivation layer, to supply the oxygen element to the superficial layer of the channel region, and ensure the oxygen element balance in the superficial layer, the first passivation layer acts as a barrier layer to ensure the stability of the TFT.