N-Type Oxide Semiconductor Coating for Low-Temperature Uniform Films

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Solution Overview

Problem

Current methods for forming n-type oxide semiconductor films, such as IGZO, face challenges in achieving uniformity and stability due to high process costs and difficulties in reducing oxygen vacancies, especially in vacuum processes, which affect the film's properties and performance.

Innovation Solution

A coating liquid comprising specific elements like Sc, Y, Ln, B, Al, Ga, In, Tl, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Ge, Sn, Pb, Sb, Bi, Se, and Te, along with a solvent, is used to form n-type oxide semiconductor films, allowing for precise control of film formation and reduction of oxygen vacancies at low temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If vacuum processes (sputtering, laser abrasion) are used to form oxide semiconductor films, then film formation is achieved, but process cost increases and uniformity of target formulation becomes difficult

Engineering Contradiction:
Improveuniformity of target formulationVSAvoidprocess cost
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces vacuum-based physical deposition processes (sputtering, laser abrasion) with a liquid-phase coating process. The coating liquid containing metal organic compounds is applied to the substrate and then heated to form the oxide semiconductor film, eliminating the need for complex vacuum equipment and achieving uniform composition through solution-phase mixing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state of the precursor material from solid targets (requiring vacuum processing) to liquid solution (enabling atmospheric processing). By dissolving metal organic compounds in a solvent and controlling the coating and heating parameters, uniform film formation is achieved at atmospheric pressure with reduced equipment complexity.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If vacuum processes are used to form oxide semiconductor films, then films are produced, but reducing oxygen vacancies becomes difficult leading to instability in film properties

Engineering Contradiction:
Improvestability of film propertiesVSAvoiddifficulty in reducing oxygen vacancies
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the oxygen atmosphere during film formation by using liquid-phase coating followed by heating in an oxygen-containing atmosphere. This approach allows oxygen to be incorporated into the film structure during the heating process, reducing oxygen vacancies and improving film stability without requiring complex vacuum control.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses metal organic compounds as intermediary precursors that decompose during heating to form the oxide semiconductor film. These organic compounds serve as a vehicle to deliver metal atoms uniformly distributed in the film, and their decomposition process facilitates oxygen incorporation, reducing oxygen vacancies.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If liquid phase methods are used to form oxide semiconductor films, then process simplicity and cost reduction are achieved, but film properties remain insufficient

Engineering Contradiction:
Improveprocess simplicityVSAvoidfilm properties
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent uses composite metal organic compounds containing multiple metal elements (In, Ga, Zn) along with organic ligands in the coating liquid. This composite approach allows precise control of stoichiometry and composition in the resulting oxide semiconductor film, achieving desired electrical properties while maintaining process simplicity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes multiple parameters including the composition of the coating liquid, coating conditions, and heating temperature/profile to achieve films with desired properties. By carefully controlling these parameters, the liquid-phase process produces films with sufficient electrical characteristics for transistor applications.

Inventive Principle:
Principle #35Parameter changes

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 enables the production of stable n-type oxide semiconductor films with desired volume resistivity and carrier density, achieving high precision and uniformity, thereby improving the performance and stability of n-type oxide semiconductor thin-film transistors (TFTs).

Implementation Method 1

a coating liquid for forming an n-type oxide semiconductor film

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 2

capable of forming a large area of an n-type oxide semiconductor film having a desired volume resistivity at a low process temperature

Methodology Applied
Scientific EffectThermal processing: Heat Treatment

Data Source

PatentEP3350839B1Coating liquid for forming n-type oxide semiconductor film, method for producing n-type oxide semiconductor film, and method for producing field-effect transistor
Publication Date: 2024.06.12 RICOH CO LTD
  • EP3350839B1 patent drawingFigure 1~3
  • EP3350839B1 patent drawingFigure 4~5D
  • EP3350839B1 patent drawingFigure 6~7

AI summary

A coating liquid for forming an n-type oxide semiconductor film, the coating liquid including: a Group A element, which is at least one selected from the group consisting of Sc, Y, Ln, B, Al, and Ga; a Group B element, which is at least one of In and Tl; a Group C element, which is at least one selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Group 7 elements, Group 8 elements, Group 9 elements, Group 10 elements, Group 14 elements, Group 15 elements, and Group 16 elements; and a solvent.