Crystalline Oxide Thin Film Composition for Compact TFT Stability
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Solution Overview
Problem
Compact thin-film transistors (TFTs) face challenges in maintaining favorable trap limiting conductivity region characteristics due to the deterioration of these characteristics when the TFTs are downsized.
Innovation Solution
A crystalline oxide thin film is developed, containing an In element as the main component, a Ga element, and an Ln element, with specific atomic composition ratios and crystal grain size ranges, to enhance mobility and stability in compact TFTs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the TFT is downsized to achieve compact design, then device integration and compactness are improved, but trap limiting conductivity region characteristics deteriorate
Solution Approach 1:
The patent changes the material parameters of the oxide semiconductor layer by controlling the crystal grain size to 0.5 μm or less and adjusting the atomic composition ratios (In/(In+Ga+Ln) ≥ 0.85, Ga/(In+Ga+Ln) ≥ 0.03, Ln/(In+Ga+Ln) ≥ 0.02), which enables compact TFTs to maintain favorable trap limiting conductivity region characteristics even at reduced sizes
Solution Approach 2:
The patent uses a composite oxide semiconductor material containing In, Ga, and Ln elements with specific composition ratios, where the combination of these elements and the controlled crystal grain structure enables both compact size and maintained electrical characteristics
2Reliability
If sputtering gas with water is used to form crystalline oxide semiconductor film, then stable TFT with high mobility is achieved, but processing device corrosion and hydrogen atom influence occur
Solution Approach 1:
The patent changes the material composition parameters by adding Ln elements to the In-Ga-O system and controlling the crystal grain size, which enables stable TFT characteristics to be achieved without requiring water-added sputtering gas, thereby avoiding device corrosion and hydrogen contamination
Data Source
AI summary
A crystalline oxide thin film contains an In element, a Ga element and an Ln element, in which the In element is a main component, the Ln element is at least one element selected from the group consisting of La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and an average crystal grain size D1 is in a range from 0.05 μm to 0.5 μm.