Oxide Semiconductor Stack for Fluorine Trapping and Oxygen Repair

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Solution Overview

Problem

Semiconductor devices with oxide semiconductor channels face challenges in maintaining high mobility and reliability due to oxygen deficiencies and impurity-related defects in the insulating layers, particularly when high indium ratios are used, leading to non-uniform oxygen distribution and variations in characteristics.

Innovation Solution

A semiconductor device configuration featuring a metal oxide layer with a high fluorine concentration, positioned over an insulating surface and in contact with the oxide semiconductor layer, which absorbs and traps fluorine impurities, reducing their concentration in the oxide semiconductor layer and improving crystallinity, while a heat treatment process supplies oxygen selectively to the oxide semiconductor layer to repair deficiencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an insulating layer with high oxygen content is formed to supply oxygen to the oxide semiconductor layer, then oxygen deficiencies are reduced, but fluorine impurities are generated in the insulating layer

Engineering Contradiction:

Improveoxygen supply to oxide semiconductor layerVSAvoidfluorine impurity concentration in insulating layer

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The insulating layer is divided into two distinct layers: a first insulating layer in contact with the oxide semiconductor layer that suppresses fluorine release, and a second insulating layer above it that supplies oxygen. This segmentation allows each layer to perform its specific function without interfering with the other, resolving the contradiction between oxygen supply and fluorine suppression.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first insulating layer acts as an intermediary between the oxide semiconductor layer and the second insulating layer. It prevents fluorine from reaching the oxide semiconductor layer while allowing oxygen to pass through to the oxide semiconductor layer, thus mediating between the conflicting requirements of fluorine suppression and oxygen supply.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If high indium ratio is used in oxide semiconductor layer to achieve high mobility, then mobility is improved, but oxygen distribution becomes non-uniform and characteristics vary

Engineering Contradiction:

Improvemobility of semiconductor deviceVSAvoiduniformity of oxygen distribution

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies different oxygen concentrations to different regions and layers: the second insulating layer has high oxygen concentration for supplying oxygen, while the first insulating layer has controlled oxygen concentration to prevent fluorine release. This local differentiation of properties ensures uniform oxygen distribution in the oxide semiconductor layer while maintaining high indium ratio for high mobility.

Inventive Principle:

Principle #3Local quality

3Reliability

If heat treatment is applied to supply oxygen to oxide semiconductor layer, then oxygen deficiencies are repaired, but fluorine impurities are released from insulating layer

Engineering Contradiction:

Improveoxygen deficiency repairVSAvoidfluorine release from insulating layer

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The insulating layer is segmented into two functional layers where the first insulating layer is specifically designed to suppress fluorine release during heat treatment, while the second insulating layer performs the oxygen supply function. This segmentation allows heat treatment to proceed effectively without the harmful side effect of fluorine release contaminating the oxide semiconductor layer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first insulating layer serves as a protective intermediary that blocks fluorine release during heat treatment while permitting oxygen to reach the oxide semiconductor layer. This intermediary function enables the heat treatment process to repair oxygen deficiencies without introducing fluorine impurities.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the mobility of the semiconductor device to greater than 30 cm2/Vs by reducing impurity scattering and uniformly addressing oxygen deficiencies, thereby improving both initial characteristics and reliability test results.

Implementation Method 1

A fluorine concentration of the metal oxide semiconductor layer is greater than or equal to 1×10^18 atoms/cm³

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

a heat treatment process supplies oxygen selectively to the oxide semiconductor layer to repair deficiencies

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS20250022966A1Semiconductor device

Publication Date: 2025.01.16 JAPAN DISPLAY INC

AI summary

A semiconductor device includes a metal oxide layer over an insulating surface and an oxide semiconductor layer over the metal oxide layer. A fluorine concentration of the metal oxide semiconductor layer is greater than or equal to 1×1018 atoms/cm3. In a SIMS analysis, a secondary ion intensity of fluorine detected in the metal oxide layer may be greater than or equal to 10 times a secondary ion intensity of fluorine detected in the oxide semiconductor layer.