Oxide Semiconductor Transistor End Face Stabilization
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Solution Overview
Problem
Transistors using oxide semiconductors exhibit abnormal electric characteristics due to impurity entry and oxygen vacancy formation at the end face portions, leading to fluctuation in current-voltage curves with a hump shape, affecting reliability and productivity.
Innovation Solution
A method is implemented to suppress impurity entry and oxygen vacancy formation by performing a plasma treatment using halogen-containing gases for electrode formation, followed by impurity removal and oxygen addition treatments, specifically using dilute hydrofluoric acid or oxalic acid for cleaning and dinitrogen monoxide plasma for oxygen addition, with a protective insulating film to stabilize the oxide semiconductor film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plasma treatment using halogen-containing gases is performed for electrode formation, then source electrode layer and drain electrode layer can be formed, but impurities enter the end face portion of the oxide semiconductor film causing abnormal electric characteristics
Solution Approach 1:
The patent applies preliminary anti-action by performing impurity removal treatment on the end face portion of the oxide semiconductor film before forming the source and drain electrode layers. This preventive measure removes impurities that would otherwise be introduced during subsequent plasma treatment, thereby preventing abnormal electric characteristics such as hump-shaped current-voltage curves while still allowing electrode formation to proceed
Solution Approach 2:
The patent applies preliminary action by performing oxygen addition treatment on the end face portion of the oxide semiconductor film before electrode formation. This preliminary oxygen supplementation prevents oxygen vacancies from forming during the plasma treatment process, ensuring stable electric characteristics while enabling subsequent electrode fabrication
2Productivity
If oxide semiconductor film is used in transistor, then transistor can be manufactured, but impurity entry and oxygen vacancy formation cause fluctuation in current-voltage characteristics with hump shape
Solution Approach 1:
The patent applies local quality by selectively treating only the end face portion of the oxide semiconductor film where impurity entry and oxygen vacancy formation occur. The impurity removal treatment and oxygen addition treatment are specifically targeted at this region, leaving the bulk of the semiconductor film unchanged. This localized approach maintains high productivity while precisely addressing the manufacturing precision issue causing hump-shaped characteristics
Solution Approach 2:
The patent performs impurity removal and oxygen addition treatments as preliminary actions before transistor operation. By pre-cleaning and pre-oxygenating the end face portion, the patent prevents abnormal electric characteristics from developing during normal transistor operation, ensuring consistent current-voltage characteristics without requiring complex post-processing
3Stability of the object's composition
If protective insulating film is formed to cover oxide semiconductor film, then stability is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent performs impurity removal and oxygen addition treatments as preliminary actions before forming the protective insulating film. By pre-treating the oxide semiconductor film to remove impurities and supply oxygen, the patent reduces the likelihood of future degradation, thereby enhancing long-term stability. The protective insulating film then serves as a simple barrier layer, keeping the overall manufacturing process relatively straightforward while achieving enhanced stability
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 stabilizes the electric characteristics of the transistors, enhancing their reliability and productivity by reducing impurity concentrations and oxygen vacancies, resulting in favorable transistor performance and high yield manufacturing.
Implementation Method 1
processing the conductive film by a plasma treatment using an etching gas containing halogen
Implementation Method 2
processing the conductive film by a plasma treatment using an etching gas containing halogen to form a source electrode layer and a drain electrode layer
Implementation Method 3
performing an impurity removal treatment on an exposed region of the end face portion of the island-shaped oxide semiconductor film to remove an element contained in the etching gas
Implementation Method 4
performing a first oxygen addition treatment on the exposed region of the end face portion of the island-shaped oxide semiconductor film
Data Source
AI summary
A highly reliable semiconductor device and a method for manufacturing the semiconductor device are provided. The semiconductor device is manufactured with a high yield, so that high productivity is achieved. In a semiconductor device including a transistor in which a source electrode layer and a drain electrode layer are provided over and in contact with an oxide semiconductor film, entry of impurities and formation of oxygen vacancies in an end face portion of the oxide semiconductor film are suppressed. This can prevent fluctuation in the electric characteristics of the transistor which is caused by formation of a parasitic channel in the end face portion of the oxide semiconductor film.