Oxide Semiconductor Transistor Sidewall Insulation
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Solution Overview
Problem
Miniaturization of transistors leads to challenges in achieving high-speed operation, low power consumption, and high integration while maintaining stable electrical characteristics and yield, particularly due to issues with oxygen release and impurity entry in oxide semiconductor films.
Innovation Solution
A semiconductor device structure incorporating an oxide semiconductor film with a gate insulating film and gate electrode layer, where a first sidewall insulating layer of aluminum oxide with crevices is covered by a second sidewall insulating layer, preventing electrical defects and supplying oxygen, and a method involving chemical mechanical polishing to form source and drain electrode layers without etching steps, ensuring precise processing and high yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the transistor is miniaturized to achieve high-speed operation and high integration, then the operating speed and integration density are improved, but the electrical characteristics become unstable due to oxygen release and impurity entry in oxide semiconductor films
Solution Approach 1:
The patent divides the sidewall insulating layer into two distinct segments: a first sidewall insulating layer made of aluminum oxide in contact with the gate electrode layer, and a second sidewall insulating layer made of a different material covering the first. This segmentation allows each layer to perform its specific function - the aluminum oxide layer supplies oxygen and prevents impurity entry, while the second layer provides additional insulation and structural support, thereby maintaining electrical stability in miniaturized transistors.
Solution Approach 2:
The first sidewall insulating layer made of aluminum oxide acts as an intermediary between the gate electrode layer and the external environment. It mediates the oxygen supply to the oxide semiconductor film and blocks the entry of impurities such as hydrogen and moisture, ensuring stable electrical characteristics while allowing the transistor to operate at miniaturized dimensions.
2Productivity
If the transistor is miniaturized to achieve high integration, then the integration density is improved, but the manufacturing yield decreases due to process variations and defects
Solution Approach 1:
The patent applies preliminary action by forming the first sidewall insulating layer of aluminum oxide before subsequent manufacturing steps. This layer is pre-formed to prevent oxygen release and impurity entry during later processing, thereby maintaining oxide semiconductor film quality and reducing defect rates in miniaturized, high-density transistor manufacturing.
Solution Approach 2:
The aluminum oxide sidewall insulating layer serves as a disposable protective element that is formed specifically for its oxygen supply and impurity blocking functions during the manufacturing process. After serving its protective purpose, it can be selectively removed or remains as part of the final structure, enabling high-yield manufacturing of miniaturized transistors without compromising quality.
3Device complexity
If a single sidewall insulating layer is used to simplify the structure, then the device complexity is reduced, but electrical defects such as short circuits and leakage currents occur due to insufficient coverage and oxygen loss
Solution Approach 1:
The patent applies local quality by assigning different materials and functions to different parts of the sidewall insulating structure. The first sidewall insulating layer made of aluminum oxide provides localized oxygen supply and impurity blocking at the critical gate electrode interface, while the second sidewall insulating layer provides additional insulation. This localized functional differentiation prevents electrical defects without requiring complex multi-layer structures throughout the entire device.
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
The solution enables high-speed operation, stable electrical characteristics, and high yield in miniaturized transistors with improved on-state characteristics and reliability, while reducing variations and productivity losses.
Implementation Method 1
The first sidewall insulating layer formed of an aluminum oxide film can supply oxygen to the oxide semiconductor film and suppress release of oxygen and entry of impurities such as hydrogen
Implementation Method 2
The second sidewall insulating layer can prevent electrical defects such as a short circuit and a leakage current between the gate electrode layer and the source and drain electrode layers
Implementation Method 3
the interlayer insulating film and the conductive film are cut (grinded or polished), so that part of the conductive film over the gate electrode layer is removed. Accordingly, the source electrode layer and the drain electrode layer are formed. As the cutting (grinding or polishing) method, a chemical mechanical polishing (CMP) method can be preferably used
Data Source
AI summary
Provided is a miniaturized transistor with stable and high electrical characteristics with high yield. In a semiconductor device including the transistor in which an oxide semiconductor film, a gate insulating film, and a gate electrode layer are stacked in this order, a first sidewall insulating layer is provided in contact with a side surface of the gate electrode layer, and a second sidewall insulating layer is provided to cover a side surface of the first sidewall insulating layer. The first sidewall insulating layer is an aluminum oxide film in which a crevice with an even shape is formed on its side surface. The second sidewall insulating layer is provided to cover the crevice. A source electrode layer and a drain electrode layer are provided in contact with the oxide semiconductor film and the second sidewall insulating layer.