Oxide Sintered Body for Sputtering Target
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Solution Overview
Problem
Existing oxide sintered bodies for sputtering targets used in thin film transistors (TFTs) face challenges in achieving high density, low volume resistivity, and thermal conductivity while maintaining stability and preventing micro-cracks and abnormal discharges during sputtering processes.
Innovation Solution
An oxide sintered body comprising a bixbyite phase represented by In2O3 and a garnet phase represented by Y3In2Ga3O12, with specific atomic ratios and a positive tetravalent metal element like Sn, forming a solid solution to enhance sintered body density and reduce bulk resistance, thereby improving sputtering target strength and thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide sintered body with high In2O3 content is used to achieve low volume resistivity, then electrical conductivity is improved, but thermal stress increases causing micro-cracks and abnormal discharges
Solution Approach 1:
The patent creates a composite sintered body containing two distinct phases: an In-rich phase (In1-xMxO3 where M is Ga, Ge, or Sn) providing low volume resistivity, and a Ga-rich phase (Ga1-yM'yO3 where M' is In, Ge, or Sn) providing thermal stress resistance. This composite structure allows simultaneous achievement of electrical conductivity and mechanical strength by distributing different functional phases throughout the material.
Solution Approach 2:
The patent applies local quality by creating regions with different compositions and properties within the sintered body. The In-rich phases are distributed throughout the matrix to provide conductivity pathways, while the Ga-rich phases form a continuous network to handle thermal stress. This local differentiation of material properties enables each phase to optimize its specific function.
2Volume of stationary object
If sintering temperature is increased to improve sintered body density, then density is improved, but micro-cracks and abnormal discharges occur during sputtering
Solution Approach 1:
The composite structure with dual phases (In-rich and Ga-rich) enables achievement of high density (95% or more of theoretical density) while maintaining sputtering stability. The Ga-rich phase acts as a stress-buffering matrix that prevents crack propagation during the high-power sputtering process, allowing the In-rich phases to provide conductivity without causing thermal stress failures.
3Reliability
If In content is increased to reduce bulk resistance, then electrical conductivity is improved, but target strength decreases and micro-cracks form
Solution Approach 1:
The patent resolves this contradiction by creating a composite where In-rich phases (providing low bulk resistance) are embedded in a Ga-rich phase matrix (providing mechanical strength). The Ga-rich phase forms a continuous network that reinforces the target structure and prevents micro-crack formation, while the dispersed In-rich phases maintain electrical conductivity pathways throughout the material.
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 solution results in a high-strength sputtering target with reduced thermal stress, preventing micro-cracks and abnormal discharges, and enabling high-performance TFTs with improved mobility and heat stability.
Implementation Method 1
An oxide sintered body comprising a bixbyite phase represented by In2O3 and a garnet phase represented by Y3In2Ga3O12, with specific atomic ratios and a positive tetravalent metal element like Sn, forming a solid solution to enhance sintered body density and reduce bulk resistance
Implementation Method 2
In forming the above-described oxide semiconductor (film), a sputtering process of sputtering a sputtering target is preferably used
Data Source
AI summary
An oxide sintered body includes a bixbyite phase represented by In2O3, and a garnet phase represented by Y3In2Ga3O12.