Oxide Semiconductor Film Stack for Impurity Diffusion Control
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Solution Overview
Problem
Oxygen vacancies and impurities such as hydrogen or moisture in the oxide semiconductor film of transistors can adversely affect the electrical characteristics of semiconductor devices, leading to fluctuations in performance and reliability.
Innovation Solution
The semiconductor device incorporates a structure with a gate electrode, insulating films, and metal oxide films that contain the same metal elements as the oxide semiconductor film, where the metal oxide films are used to inhibit the diffusion of oxygen and impurities, ensuring minimal oxygen vacancies and impurities in the oxide semiconductor film, thereby stabilizing the electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen is introduced through the oxide insulating layer and heat treatment is performed to remove impurities, then the purity of the oxide semiconductor layer is improved, but the manufacturing process complexity increases
Solution Approach 1:
The oxide insulating layer is formed with excess oxygen content before the oxide semiconductor layer is deposited. This preliminary oxygen supply eliminates the need for subsequent oxygen introduction and heat treatment steps, as the oxygen is already available during the deposition process to fill vacancies and prevent impurity formation, thereby simplifying the manufacturing process while maintaining high purity
Solution Approach 2:
The oxide insulating layer serves a dual function: it acts as both an insulating layer and an oxygen reservoir that automatically supplies oxygen to the oxide semiconductor layer during deposition. This self-service mechanism eliminates the need for separate oxygen introduction processes, reducing manufacturing complexity while ensuring high oxide semiconductor layer purity
2Stability of the object's composition
If the oxide semiconductor film is highly purified to reduce oxygen vacancies and impurities, then the electrical characteristics stability is improved, but the manufacturing time and energy consumption increase
Solution Approach 1:
The oxide insulating layer is pre-formed with excess oxygen content before oxide semiconductor deposition. This preliminary oxygen preparation occurs during the insulating layer formation step, eliminating the need for separate oxygen introduction and prolonged heat treatment steps, thereby reducing manufacturing time while ensuring high purity and electrical stability
Solution Approach 2:
The functions of forming the oxide insulating layer and preparing oxygen supply are merged into a single process step. The oxide insulating layer simultaneously serves as the insulating barrier and the oxygen reservoir, eliminating the need for separate oxygen introduction processes and reducing overall manufacturing time while maintaining high electrical characteristics stability
3Reliability
If multiple metal oxide films are stacked to inhibit diffusion of oxygen and impurities, then the reliability is improved, but the device structure complexity increases
Solution Approach 1:
The oxide insulating layer acts as an intermediary oxygen reservoir between the oxide semiconductor layer and the external environment. It mediates oxygen supply to the semiconductor layer while blocking external impurities, eliminating the need for multiple protective metal oxide films and their associated diffusion barrier functions, thereby reducing structural complexity while maintaining high reliability
4Stability of the object's composition
If oxygen vacancies are minimized in the channel region, then the threshold voltage stability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The oxide insulating layer is pre-formed with excess oxygen content at the interface region before oxide semiconductor deposition. This preliminary oxygen preparation ensures that oxygen vacancies are filled during the deposition process itself, achieving high threshold voltage stability without requiring extremely precise control of subsequent processing parameters
Solution Approach 2:
The oxide insulating layer automatically supplies oxygen to the oxide semiconductor layer during deposition through diffusion. This self-service oxygen supply mechanism occurs naturally during the deposition process without requiring precise external control of oxygen introduction parameters, thereby achieving high oxygen vacancy control with relaxed manufacturing precision requirements
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 configuration effectively inhibits changes in electrical characteristics and improves the reliability of semiconductor devices by reducing oxygen vacancies and impurities, resulting in stable and low-power consumption performance.
Implementation Method 1
a first metal oxide film over the second insulating film; and a second metal oxide film over the first metal oxide film. The first metal oxide film contains at least one metal element that is the same as a metal element contained in the oxide semiconductor film
Data Source
AI summary
A change in electrical characteristics in a semiconductor device including an oxide semiconductor film is inhibited, and the reliability is improved. The semiconductor device includes a gate electrode, a first insulating film over the gate electrode, an oxide semiconductor film over the first insulating film, a source electrode electrically connected to the oxide semiconductor film, a drain electrode electrically connected to the oxide semiconductor film, a second insulating film over the oxide semiconductor film, the source electrode, and the drain electrode, a first metal oxide film over the second insulating film, and a second metal oxide film over the first metal oxide film. The first metal oxide film contains at least one metal element that is the same as a metal element contained in the oxide semiconductor film. The second metal oxide film includes a region where the second metal oxide film and the first metal oxide film are mixed.