Transistor Functional Layer Prevents Undercut Defects
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Solution Overview
Problem
Semiconductor devices, particularly transistors, face challenges in maintaining stable and favorable electrical characteristics due to shape defects and increased wiring resistance in large-screen, high-definition display devices, which can lead to unreliable performance.
Innovation Solution
A semiconductor device structure is proposed, featuring a transistor with a specific layer configuration including a semiconductor layer, a first insulating layer, a metal oxide layer, a functional layer, and a conductive layer, where the etching rates of the functional layer are lower than the conductive layer, and the layers have overlapping regions with the semiconductor layer, preventing undercut formation and ensuring adhesion, thereby reducing shape defects and improving electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductive layer is etched to form wiring patterns, then wiring resistance can be reduced for large-screen displays, but undercut formation occurs at layer interfaces causing shape defects
Solution Approach 1:
A functional layer is introduced as an intermediary between the conductive layer and the first insulating layer. This functional layer has an etching rate lower than the conductive layer, which prevents undercut formation during etching while still allowing the conductive layer to be properly patterned. The functional layer acts as a buffer that maintains the structural integrity of the layer stack during the etching process.
Solution Approach 2:
The etching rate parameter is carefully controlled by selecting materials with appropriate etching characteristics. The functional layer is chosen to have a lower etching rate than the conductive layer, which fundamentally changes the etching behavior at the interface and prevents the undercut phenomenon that would otherwise occur.
2Reliability
If multiple layers are stacked to improve transistor performance, then field-effect mobility increases, but adhesion between layers becomes critical to prevent defects
Solution Approach 1:
The functional layer serves as an adhesion promoter between the conductive layer and the first insulating layer. By positioning this layer with appropriate material properties in the intermediate position, it ensures strong bonding between the adjacent layers, preventing delamination and other adhesion-related defects in the multi-layer structure.
Solution Approach 2:
The patent employs a composite multi-layer structure where each layer is made of materials with specific properties. The functional layer is selected from materials that provide both good adhesion to adjacent layers and appropriate etching characteristics, creating a composite structure that achieves multiple functions simultaneously.
Data Source
AI summary
A transistor in which shape defects are unlikely to occur is provided. A transistor with favorable electrical characteristics is provided. A semiconductor device with favorable electrical characteristics is provided. The semiconductor device includes a transistor. The transistor includes a semiconductor layer, a first insulating layer, a metal oxide layer, a functional layer, and a conductive layer. The first insulating layer is positioned over the semiconductor layer. The metal oxide layer is positioned over the first insulating layer. The functional layer is positioned over the metal oxide layer. The conductive layer is positioned over the functional layer. The semiconductor layer, the first insulating layer, the metal oxide layer, the functional layer, and the conductive layer have regions overlapping with each other. In the channel length direction of the transistor, end portions of the first insulating layer, the metal oxide layer, the functional layer, and the conductive layer are positioned inward from an end portion of the semiconductor layer. An etching rate of the functional layer with an etchant containing one or more of phosphoric acid, acetic acid, nitric acid, hydrochloric acid, and sulfuric acid is lower than an etching rate of the conductive layer.