LiCoO2 Sputtering Target for High-Speed DC Deposition
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Solution Overview
Problem
Conventional sputtering targets for forming positive electrode thin films in all-solid-state thin-film lithium ion batteries have high resistivity, making it difficult to achieve high-speed deposition using DC sputtering, which is necessary for improving productivity and reducing the time required to increase battery capacity.
Innovation Solution
A LiCoO2 sputtering target with a composition of LiCoO2 is developed, characterized by an average resistivity of 100 Ωcm or less and a relative density of 80% or higher, achieved through specific sintering and heat treatment conditions, allowing for stable and efficient DC sputtering and minimizing abnormal discharge during deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional target material with high resistivity (1 to 500 kΩ or higher) is used, then RF sputtering can be performed, but high speed deposition via DC sputtering cannot be achieved
Solution Approach 1:
The patent changes the electrical resistivity parameter of the sputtering target from conventional high values (1-500 kΩ) to a specific low range (1-100 Ω). This is achieved by controlling the sintering temperature (950-1150°C) and relative density (80% or higher) of the LiCoO2 target material. The parameter change enables DC sputtering to proceed stably, allowing high speed deposition that was previously impossible with conventional high-resistivity targets.
2Productivity
If sputtering target with low resistivity is used to enable DC sputtering, then high speed deposition is achieved, but target density and uniformity may be compromised
Solution Approach 1:
The patent simultaneously optimizes multiple parameters: resistivity (1-100 Ω), relative density (80% or higher), and sintering temperature (950-1150°C). By coordinating these parameter changes, the invention achieves low resistivity for DC sputtering while maintaining high density and uniformity for stable film deposition, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
Conventionally, high density sintering was pursued first and then resistivity was addressed. This patent inverts the approach by prioritizing resistivity reduction through controlled sintering conditions, then achieving high density (80% or higher) as a secondary optimization. This inversion enables DC sputtering to be the primary goal, with film uniformity maintained through the inverted process sequence.
3Reliability
If high density sintering is performed to reduce resistivity, then DC sputtering becomes feasible, but sintering temperature control becomes critical
Solution Approach 1:
The patent identifies a specific sintering temperature range (950-1150°C) that simultaneously achieves the desired resistivity (1-100 Ω) and relative density (80% or higher). This parameter specification transforms the critical temperature control issue into a defined process window, enabling reliable DC sputtering while providing clear manufacturing guidelines for temperature control.
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 high-speed deposition of uniform positive electrode thin films with stable charging/discharging characteristics, reducing the generation of abnormal discharge and improving the productivity of all-solid-state thin-film lithium ion secondary batteries.
Implementation Method 1
The positive electrode materials and solid electrolyte films configuring this kind of thin-film lithium ion battery are prepared via the sputtering method
Implementation Method 2
hot pressing a lithium cobalt oxide powder at 600 to 950° C., and thereafter performing heat treatment
Implementation Method 3
performing heat treatment at 950 to 1150° C. in an atmosphere or in an oxygen atmosphere to produce a target
Data Source
AI summary
A sputtering target having a composition of LiCoO2, wherein a resistivity of the target is 100 Ωcm or less, and a relative density is 80% or higher. The sputtering target of the present invention is effective for use in forming a positive electrode thin film in all-solid-state thin-film lithium ion secondary batteries equipped in vehicles, information and communication electronics, household appliances, and the like.