IGZO Sputtering Target Crack Control via Sintering Parameters
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Solution Overview
Problem
IGZO sintered compacts with a (111) composition face challenges in achieving high transverse intensity and low bulk resistance, leading to issues like crack generation, uneven heating, and reduced yield in mass production, as well as difficulties in stable DC sputtering due to high bulk resistance.
Innovation Solution
The IGZO sintered compact is characterized by controlling the average and maximum crack lengths within specific ranges (3 μm to 15 μm and 6 μm to 45 μm, respectively) and maintaining a transverse intensity of 50 MPa or more and a bulk resistance of 100 mΩcm or less, with a Zn-rich composition and optimal atomic ratios, to ensure stable DC sputtering and reduced particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sintering time is drastically shortened to 1 to 2 hours to inhibit crystal grain growth and increase transverse intensity, then the transverse intensity is improved, but the structure becomes uneven between surface and inside, warping and strains occur, and yield deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling sintering temperature (1023K to 1273K range) and time (0.5 to 48 hours range) to achieve optimal crystal grain growth. This resolves the contradiction by finding the right balance point where transverse intensity is sufficiently high while avoiding structural unevenness and warping that occur with overly short sintering times.
Solution Approach 2:
The patent introduces dynamic control of sintering parameters, allowing adjustment of temperature and time based on specific requirements. By making the sintering process adaptable rather than fixed, the method can optimize for both strength and reliability depending on the application, resolving the trade-off between transverse intensity and yield.
2Strength
If the sintering time is drastically shortened with an electric furnace to suppress crystal grain growth, then the transverse intensity is increased, but the structure becomes uneven and the sintered compact is subject to warping or strains, leading to deterioration in yield
Solution Approach 1:
The patent uses parameter changes by establishing specific ranges for sintering temperature (1023K to 1273K) and time (0.5 to 48 hours) to control crystal grain growth uniformly. This resolves the contradiction by preventing both excessive grain growth and the structural unevenness that occurs with too-short sintering times.
Solution Approach 2:
The patent applies preliminary action by pre-determining optimal sintering parameters before the actual sintering process. By establishing the temperature and time ranges in advance based on material properties, the method ensures uniform structural development from the beginning, preventing warping and strains before they can occur.
3Productivity
If the bulk resistance is high, then DC sputtering becomes difficult and high power is needed to attain practical deposition rate, but when power is increased, the probability of abnormal discharge increases causing particles and cracks
Solution Approach 1:
The patent applies parameter changes by controlling sintering conditions to achieve specific bulk resistance values (50-500 mΩ·cm range). By optimizing the electrical conductivity parameter through controlled sintering, the material enables DC sputtering at practical power levels without abnormal discharge, resolving the contradiction between deposition rate and harmful effects.
4Strength
If microwave heating is used to achieve rapid heating and short-time sintering, then the transverse intensity is increased, but uneven heating due to local heating occurs and the size of the sintered compact is restricted
Solution Approach 1:
The patent resolves this contradiction by changing the heating method from microwave to resistance heating, and by precisely controlling temperature and time parameters. This approach achieves high transverse intensity while maintaining heating uniformity across the entire compact, including large-sized samples that cannot be processed by microwave heating.
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 results in a sputtering target with high mechanical strength and low bulk resistance, enabling stable DC sputtering with minimal particle generation and improved thin film quality, suitable for mass production of oxide semiconductor films.
Implementation Method 1
the growth of crystal grains is fast and, therefore, the adjustment of the grain size is difficult
Implementation Method 2
An IGZO film is generally deposited by sputtering a target which is prepared from an IGZO sintered compact
Data Source
AI summary
An IGZO sintered compact composed of indium (In), gallium (Ga), zinc (Zn), oxygen (O) and unavoidable impurities, wherein an average length of cracks existing in the IGZO sintered compact is 3 μm or more and 15 μm or less. Provided is a sputtering target capable of suppressing the target cracks and reducing the generation of particles during deposition via DC sputtering, and forming favorable thin films.