Oxide Semiconductor Device Oxygen Vacancy Control

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Solution Overview

Problem

Semiconductor devices with oxide semiconductors face issues of defective electrical characteristics due to oxygen vacancies and impurities like hydrogen, silicon, and nitrogen, leading to unstable performance and increased leakage current.

Innovation Solution

A semiconductor device structure is implemented where oxygen is supplied to the channel formation region from a base insulating layer to fill oxygen vacancies, and a protective insulating layer with low oxygen permeability is used to prevent further oxygen release, while oxide layers with metal elements are placed to separate the channel from insulating layers, reducing impurity concentrations and interface states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If oxygen is supplied from the base insulating layer to fill oxygen vacancies, then electrical characteristics are improved, but oxygen may be released to layers other than the oxide semiconductor layer causing defects

Engineering Contradiction:

Improveelectrical characteristicsVSAvoidoxygen release to wrong layers

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The protective insulating layer acts as an intermediary barrier between the base insulating layer and other layers. It has low permeability to oxygen, preventing oxygen from reaching layers other than the oxide semiconductor layer while allowing controlled oxygen supply to fill vacancies in the channel formation region.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective insulating layer is selectively positioned to cover side surfaces of the gate insulating layer and oxide layer only in regions where oxygen barrier protection is needed, while allowing oxygen supply to the channel formation region. This localized application achieves different functions in different areas.

Inventive Principle:

Principle #3Local quality

2Reliability

If the protective insulating layer with low oxygen permeability is formed to prevent oxygen release, then oxygen vacancies are prevented, but hydrogen and other impurities may still enter the oxide semiconductor layer

Engineering Contradiction:

Improveoxygen vacancy preventionVSAvoidimpurity entry

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protective insulating layer forms a thin film barrier with low permeability to oxygen and hydrogen. This flexible barrier layer effectively blocks the entry of harmful impurities while maintaining the structural integrity of the device.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If oxide layers containing metal elements are provided to separate the channel from insulating layers, then impurity concentrations are reduced, but device structure becomes more complex

Engineering Contradiction:

Improveimpurity concentration reductionVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The device structure is segmented into distinct functional layers: the oxide layer containing metal elements (In, Ga, Zn) acts as a buffer between the gate insulating layer and the oxide semiconductor layer. This segmentation creates clear functional zones that reduce impurity diffusion while maintaining manufacturability.

Inventive Principle:

Principle #1Segmentation

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 results in a highly purified intrinsic oxide semiconductor layer with stable electrical characteristics, reduced defects, and improved reliability by minimizing oxygen vacancies and impurity effects, leading to enhanced transistor performance.

Implementation Method 1

oxygen is supplied from a base insulating layer provided below an oxide semiconductor layer to a channel formation region

Methodology Applied

Scientific EffectOxygen diffusion: Diffusion

Implementation Method 2

protective insulating layer containing a small amount of hydrogen and functioning as a barrier layer having a low permeability to oxygen

Methodology Applied

Scientific EffectOxygen barrier: Permeation

Data Source

PatentUS9190527B2Semiconductor device and manufacturing method of semiconductor device

Publication Date: 2015.11.17 SEMICON ENERGY LAB CO LTD

AI summary

A highly reliable semiconductor device including an oxide semiconductor is provided. Oxygen is supplied from a base insulating layer provided below an oxide semiconductor layer to a channel formation region, whereby oxygen vacancies which might be generated in the channel formation region are filled. Further, a protective insulating layer containing a small amount of hydrogen and functioning as a barrier layer having a low permeability to oxygen is formed over the gate electrode layer so as to cover side surfaces of an oxide layer and a gate insulating layer that are provided over the oxide semiconductor layer, whereby release of oxygen from the gate insulating layer and/or the oxide layer is prevented and generation of oxygen vacancies in a channel formation region is prevented.