Metal Oxide Semiconductor Layer Structure for Stable TFT Characteristics

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Solution Overview

Problem

Current semiconductor devices face challenges in achieving favorable and stable electrical characteristics, particularly in ensuring low oxygen vacancies and carrier density in metal oxide semiconductor layers, which affect the reliability and performance of transistors used in display devices.

Innovation Solution

The semiconductor device incorporates a metal oxide semiconductor layer with specific regions having different impurity concentrations and hydrogen content, where boron, phosphorus, or magnesium elements are bonded to oxygen, and hydrogen is supplied to reduce resistance and prevent oxygen diffusion, thereby creating regions with low carrier density and high reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal oxide semiconductor layers are used to achieve high field-effect mobility, then transistor performance is improved, but oxygen vacancies and carrier density increase leading to unstable electrical characteristics

Engineering Contradiction:

Improveelectrical characteristics stabilityVSAvoidoxygen vacancies and carrier density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by creating distinct regions within the semiconductor layer: a channel formation region with low impurity concentration for stable electrical characteristics, and source/drain regions with high impurity concentration for low resistance. This spatial differentiation of material properties resolves the contradiction by allowing the channel region to maintain low oxygen vacancies while source/drain regions provide necessary conductivity through controlled doping.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes parameter changes by controlling impurity concentration and performing heat treatment at specific temperatures (400-700°C) to adjust the electrical characteristics. By changing the impurity concentration parameter in different regions and using heat treatment to reduce oxygen vacancies, the patent achieves both high mobility and stable electrical characteristics.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If impurity elements are added to reduce resistance in source and drain regions, then conductivity is improved, but oxygen diffusion and carrier density increase affecting channel region stability

Engineering Contradiction:

Improvesource/drain region conductivityVSAvoidoxygen diffusion into channel region

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by clearly separating the semiconductor layer into distinct functional regions: channel formation region, source region, and drain region. Each region has specifically controlled impurity concentrations to perform its designated function without interfering with others, preventing oxygen diffusion from source/drain regions into the channel region.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses an intermediary approach by introducing a barrier layer or controlling the interface structure between source/drain regions and channel region. This intermediary structure prevents oxygen diffusion from the high-impurity source/drain regions into the low-impurity channel region, while still allowing the source/drain regions to maintain their low resistance characteristics.

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 structure achieves semiconductor devices with improved electrical characteristics, reduced oxygen vacancies, and enhanced reliability by maintaining low resistance and carrier density, leading to more stable and efficient transistor performance.

Implementation Method 1

hydrogen is supplied to reduce resistance

Methodology Applied

Scientific EffectHydrogenation: Hydrogenation

Implementation Method 2

boron, phosphorus, or magnesium elements are bonded to oxygen

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Implementation Method 3

hydrogen is supplied to reduce resistance and prevent oxygen diffusion

Methodology Applied

Scientific EffectDiffusion Barrier: Diffusion Barrier

Data Source

PatentUS11799032B2Semiconductor device and method for manufacturing semiconductor device

Publication Date: 2023.10.24 SEMICON ENERGY LAB CO LTD

AI summary

A semiconductor device with favorable electrical characteristics is provided. A semiconductor device with stable electrical characteristics is provided.The semiconductor device includes a semiconductor layer, a first insulating layer, and a first conductive layer. The first insulating layer is provided over the semiconductor layer. The first conductive layer is provided over the first insulating layer. The semiconductor layer includes a first region that overlaps with the first conductive layer and the first insulating layer, a second region that does not overlap with the first conductive layer and overlaps with the first insulating layer, and a third region that overlaps with neither the first conductive layer nor the first insulating layer. The semiconductor layer contains a metal oxide. The second region and the third region contain a first element. The first element is one or more elements selected from boron, phosphorus, aluminum, and magnesium. The first element exists in a state of being bonded to oxygen.