Multi-Target Sputtering for Uniform Lithium Film Deposition
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Solution Overview
Problem
Conventional lithium oxide sputtering processes for battery fabrication face limitations such as slow deposition rates and non-uniform deposition due to mismatched sputtering properties of individual targets, making it economically difficult to manufacture thick cathode films with high energy density and fast charging/discharging capabilities.
Innovation Solution
The use of a pair of sputtering targets with lithium-containing members, each having a conductivity of at least 5×10−6 S·cm−1, and an impedance matching circuit to adjust the impedance of one target to be within ±10% of the other, energized with electrical power at a frequency of 10 to 100 kHz, ensures uniform and high deposition rates of lithium-containing films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional radio frequency magnetron sputtering processes are used, then lithium-containing films can be deposited, but the deposition rate is slow (around 0.2 microns per hour)
Solution Approach 1:
The patent divides a single large sputtering target into multiple smaller target segments arranged in an array. Each segment is independently sputtered, allowing the total deposition area to be much larger than a single target could provide. This segmentation enables higher overall deposition rates while maintaining process control, directly resolving the contradiction between productivity and manufacturing time.
2Productivity
If multiple target sputtering processes are used to increase deposition rates, then thicker cathode layers can be achieved, but the sputtering properties of different targets do not match resulting in non-uniform deposition
Solution Approach 1:
The patent carefully controls and matches key parameters across all target segments including material composition, thickness, and electrical properties (conductivity/impedance). By standardizing these parameters, all segments sputter at comparable rates, ensuring uniform deposition across the entire substrate area while maintaining high productivity through the multi-target configuration.
Solution Approach 2:
The patent ensures all target segments have homogeneous properties - same material composition, same thickness, and matched electrical characteristics. This homogeneity across all segments ensures that each target contributes equally to the deposition process, eliminating the non-uniformity problem that plagues conventional multi-target sputtering while preserving the high deposition rate advantage.
3Productivity
If increasing sputter deposition rates is attempted, then thicker cathode films can be deposited faster, but plasma arcing occurs which affects film quality
Solution Approach 1:
By dividing the total sputtering power across multiple smaller target segments rather than concentrating it on a single large target, the power density at each segment remains lower and more manageable. This prevents plasma arcing while still achieving high overall deposition rates through the combined output of all segments, thus maintaining both productivity and film quality reliability.
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 higher deposition rates and improved electrochemical properties of the lithium-containing films, achieving higher energy density and faster charging/discharging capabilities while maintaining film quality and uniformity.
Implementation Method 1
A method of depositing lithium-containing films on a battery substrate in a sputtering chamber
Data Source
AI summary
A method of depositing lithium-containing films on a battery substrate in a sputtering chamber is provided. At least one pair of sputtering targets that each comprise a lithium-containing sputtering member is provided in the sputtering chamber, the sputtering targets selected to each have a conductivity of at least about 5×10−6 S·cm−1. A substrate carrier holding at least one battery substrate is placed in the sputtering chamber. A pressure of sputtering gas is maintained in the sputtering chamber. The sputtering gas is energized by applying to the pair of sputtering targets, an electrical power at a frequency of from about 10 to about 100 kHz.