HfInZnO Oxide Transistor Channel Composition for Thermal Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional thin film transistors (TFTs) have unstable characteristics due to sensitivity to external environments like light and moisture, and low thermal stability, which affects their performance in applications such as flat panel displays.

Innovation Solution

The use of hafnium-indium-zinc-oxide (HfInZnO) channel layers with distinct composition ratios and thicknesses for the front and back channel regions, where the back channel region has lower In content and higher Hf content, and a thickness of 1-40 nm, to maintain stability and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If oxide layers are used as channel layers to improve carrier mobility, then operating characteristics are improved, but thermal stability deteriorates and sensitivity to external environment increases

Engineering Contradiction:

Improvecarrier mobilityVSAvoidthermal stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The channel layer is divided into two regions with different compositions: the front channel region (near gate) has higher In content for high carrier mobility, while the back channel region (far from gate) has lower In content and higher Hf content for improved thermal stability and reduced environmental sensitivity. This local differentiation resolves the contradiction by optimizing each region for its specific function.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The channel layer uses a composite HfInZnO structure with spatially varying composition ratios. The front region contains more In (higher conductivity) while the back region contains more Hf (higher stability), creating a composite structure that simultaneously achieves both high mobility and thermal stability throughout the channel layer.

Inventive Principle:

Principle #40Composite materials

2Speed

If oxide layers are used as channel layers to improve carrier mobility, then operating characteristics are improved, but sensitivity to light and moisture increases

Engineering Contradiction:

Improvecarrier mobilityVSAvoidsensitivity to external environment

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The back channel region is specifically engineered with lower In content (10-30 at%) and higher Hf content (3-20 at%) to create a composition that is less sensitive to light and moisture. This local quality adjustment in the region most exposed to environmental factors resolves the contradiction between maintaining high mobility and reducing environmental sensitivity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The composite HfInZnO channel layer combines regions with different compositions: the front region optimized for mobility and the back region (with higher Hf content) optimized for environmental stability. This composite structure allows the transistor to maintain high carrier mobility while the Hf-rich back region provides protection against light and moisture effects.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8912536B2Transistors, methods of manufacturing the same and electronic devices including transistors

Publication Date: 2014.12.16 SAMSUNG ELECTRONICS CO LTD

AI summary

An oxide transistor includes: a channel layer formed of an oxide semiconductor; a source electrode contacting a first end portion of the channel layer; a drain electrode contacting a second end portion of the channel layer; a gate corresponding to the channel layer; and a gate insulating layer disposed between the channel layer and the gate. The oxide semiconductor includes hafnium-indium-zinc-oxide (HfInZnO). An electrical conductivity of a back channel region of the channel layer is lower than an electrical conductivity of a front channel region of the channel layer.