InGaZnO Sputtering Target Atomic Ratio Optimization
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Solution Overview
Problem
Existing sputtering targets for forming oxide thin films, particularly those with a homologous structure represented by InGaO3(ZnO), face challenges in achieving a single crystal form with low Ga content, leading to variations in film thickness and carrier density due to sensitivity to oxygen partial pressure and plasma density, and often result in high resistance and low density.
Innovation Solution
A sputtering target with a specific atomic ratio of In, Ga, and Zn, ranging from 0.28 to 0.38 for Zn/(In+Zn+Ga) and 0.18 to 0.28 for Ga/(In+Zn+Ga), ensuring a homologous crystal structure of InGaO3(ZnO) as the main component, which suppresses the generation of other crystal structures and maintains stability in film-forming speed, reducing sensitivity to oxygen partial pressure and facilitating controlled carrier density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a target with low Ga content and homologous structure InGaO3(ZnO) is used, then carrier density suitable for semiconductor applications can be achieved, but film thickness varies due to sensitivity to oxygen partial pressure and plasma density
Solution Approach 1:
The patent changes the atomic ratio parameters of In, Ga, and Zn in the sputtering target to achieve a homologous crystal structure. Specifically, it controls the atomic ratio within ranges: In: 0.35-0.45, Ga: 0.15-0.25, Zn: 0.40-0.50. This parameter optimization reduces oxygen bonding strength while maintaining semiconductor-appropriate carrier density, thereby decreasing sensitivity to oxygen partial pressure variations and improving film thickness uniformity.
Solution Approach 2:
The patent uses a composite oxide material comprising In, Ga, Zn, and O with a homologous crystal structure represented by InGaO3(ZnO). This composite material structure, where multiple metal oxides are integrated in specific ratios, creates a balanced bonding environment that reduces excessive oxygen bonding strength, allowing stable film formation with controlled carrier density and reduced sensitivity to process condition variations.
2Reliability
If a target with atomic ratio In:Ga = 1:1 is used to achieve single crystal form, then quality control is improved, but film thickness becomes sensitive to oxygen partial pressure variation
Solution Approach 1:
The patent modifies the atomic ratio parameters from the conventional In:Ga = 1:1 ratio to a optimized range where In: 0.35-0.45, Ga: 0.15-0.25, Zn: 0.40-0.50. This parameter change maintains the homologous crystal structure for quality control while adjusting the overall Ga content to reduce excessive oxygen bonding strength, thereby stabilizing film thickness against oxygen partial pressure variations.
3Shape
If a target with excessive Ga content is used, then single crystal form can be produced, but resistance becomes high and density becomes low
Solution Approach 1:
The patent optimizes the atomic ratio parameters by controlling Ga content within 0.15-0.25 (reducing excessive Ga) while maintaining In at 0.35-0.45 and Zn at 0.40-0.50. This parameter optimization preserves the homologous crystal structure for single crystal formation while reducing excessive oxygen bonding strength, thereby achieving appropriate electrical resistance and improved density.
Solution Approach 2:
The patent employs a composite oxide material with balanced In, Ga, Zn ratios forming a homologous structure. This composite approach distributes the functional roles: In provides carrier density, Ga controls crystal structure, and Zn stabilizes the lattice. The balanced composition achieves single crystal formation with appropriate electrical properties and density.
4Stability of the object's composition
If a target with balanced atomic ratio In:Ga:Zn = 1:1:1 is used, then homogenous film can be formed, but it is difficult to produce single crystal form
Solution Approach 1:
The patent adjusts the atomic ratio parameters from the 1:1:1 ratio to optimized ranges: In: 0.35-0.45, Ga: 0.15-0.25, Zn: 0.40-0.50. This parameter change maintains compositional homogeneity for uniform film formation while creating the specific stoichiometric conditions necessary for homologous crystal structure formation, enabling single crystal production.
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
The target enables the formation of films with carrier densities suitable for semiconductor applications at stable film-forming speeds, with improved mobility and reduced resistance, while maintaining high relative density and transverse rupture strength, thus enhancing the reproducibility and uniformity of thin film transistors.
Implementation Method 1
A sputtering target and thin film transistor equipped with same... As the method for forming this oxide film, a physical film-forming method such as sputtering...
Data Source
AI summary
A sintered body including an oxide that includes In, Ga and Zn at the following atomic ratio and includes a compound having as a main component a homologous crystal structure represented by InGaO3(ZnO):0.28≦Zn/(In+Zn+Ga)≦0.380.18≦Ga/(In+Zn+Ga)≦0.28.