Oxide Semiconductor Film Oxygen Defect Compensation
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Solution Overview
Problem
Transistors formed using oxide semiconductors suffer from oxygen defects when exposed to reduced-pressure atmospheres during manufacturing, leading to increased leakage current and shifts in threshold voltage due to oxygen deficiency, degrading their electrical characteristics.
Innovation Solution
An insulating film containing excess oxygen is provided in contact with the oxide semiconductor film to prevent oxygen release and diffusion, using materials like silicon oxide, silicon oxynitride, or aluminum oxide that release oxygen during heat treatment to compensate for defects and improve film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an oxide semiconductor film is exposed to a reduced-pressure atmosphere during manufacturing, then the manufacturing process can be completed, but oxygen defects are formed in the oxide semiconductor film causing increased leakage current and threshold voltage shifts
Solution Approach 1:
An insulating film containing excess oxygen is formed in contact with the oxide semiconductor film before the oxygen defect problem occurs. This preliminary action ensures that oxygen is available to compensate for any oxygen loss during subsequent reduced-pressure manufacturing steps, preventing oxygen defects and maintaining electrical characteristics.
Solution Approach 2:
The insulating film acts as an intermediary oxygen reservoir between the external environment and the oxide semiconductor film. It releases oxygen to the oxide semiconductor film when oxygen deficiency occurs, serving as a protective buffer that prevents direct oxygen loss to the reduced-pressure atmosphere.
2Manufacturing precision
If measures are taken to prevent hydrogen entry in the oxide semiconductor, then threshold voltage fluctuation is reduced, but oxygen defects still occur when exposed to reduced-pressure atmosphere
Solution Approach 1:
The insulating film with excess oxygen is prepared in advance, before any oxygen loss occurs. This ensures that when reduced-pressure exposure causes oxygen deficiency, the oxygen is already available from the insulating film to compensate, addressing both hydrogen prevention and oxygen stability requirements.
Solution Approach 2:
The insulating film is designed with oxygen content exceeding the stoichiometric proportion, changing the oxygen parameter to create an oxygen reservoir. This parameter change enables the insulating film to release oxygen to the oxide semiconductor film when needed, maintaining oxygen stability without compromising threshold voltage control.
3Reliability
If the oxide semiconductor film is kept in contact with oxygen-rich environment, then oxygen defects are prevented, but manufacturing complexity increases due to additional insulating film formation
Solution Approach 1:
The insulating film serves multiple functions: it acts as an oxygen reservoir to prevent oxygen defects, provides electrical insulation, and can serve as a barrier layer. This multi-functionality justifies the additional structure by delivering multiple benefits from a single added component.
Solution Approach 2:
By changing the oxygen content parameter of the insulating film to exceed stoichiometric proportions, the film gains the ability to release oxygen dynamically. This parameter change transforms a simple insulating layer into an active oxygen compensation mechanism without requiring complex additional structures.
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 reduces oxygen defects, minimizes leakage current, stabilizes the threshold voltage, and enhances the overall electrical performance of the transistor by ensuring adequate oxygen levels within the semiconductor film.
Implementation Method 1
using materials like silicon oxide, silicon oxynitride, or aluminum oxide that release oxygen during heat treatment to compensate for defects
Implementation Method 2
an insulating film containing excess oxygen is provided in contact with the oxide semiconductor film to prevent release of oxygen from the oxide semiconductor film
Data Source
AI summary
A semiconductor device which includes an oxide semiconductor and has favorable electrical characteristics is provided. In the semiconductor device, an oxide semiconductor film and an insulating film are formed over a substrate. Side surfaces of the oxide semiconductor film are in contact with the insulating film. The oxide semiconductor film includes a channel formation region and regions containing a dopant between which the channel formation region is sandwiched. A gate insulating film is formed on and in contact with the oxide semiconductor film. A gate electrode with sidewall insulating films is formed over the gate insulating film. A source electrode and a drain electrode are formed in contact with the oxide semiconductor film and the insulating film.