Conductive LiPON Sputtering Target for Uniform Large-Area Deposition
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Solution Overview
Problem
Existing technologies face challenges in efficiently depositing a layer of LiPON on a substrate, particularly in the uniformity and stability of large-area substrates, due to issues with RF sputtering, and RF sputtering, and RF sputtering, and the inability to achieve uniformity and stability of LiPON layers on large substrates, especially with RF sputtering, and the difficulty in applying RF fields uniformly across large targets.
Innovation Solution
A conductive sputtering target comprising M-doped LixPOy with a lamellar structure of microscopic splats, allowing for AC or DC sputtering processes, including pulsed-DC, and a method of forming this target through spraying particles onto a backing substrate, which mitigates stress and enables large-area coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RF sputtering is used to deposit LiPON from a Li3PO4 target, then the deposited layer has low electronic conductivity and high ionic conductivity, but uniform deposition on large substrate area is challenging due to standing wave effects and RF field uniformity issues
Solution Approach 1:
The patent changes the electrical conductivity parameter of the target material from insulating (Li3PO4) to conductive (carbon-doped Li3PO4), enabling the use of DC or pulsed-DC sputtering instead of RF sputtering. This parameter change eliminates standing wave effects and achieves uniform deposition across large substrate areas while maintaining the desired ionic conductivity of the LiPON layer.
Solution Approach 2:
The patent introduces carbon as a temporary conductive additive in the target material that serves its purpose during sputtering but is subsequently removed or converted. The carbon reacts with oxygen during sputtering to form CO and CO2 that are pumped out, leaving no carbon in the final deposited layer. This allows the target to be conductive during processing but the final product to be pure LiPON.
2Area of stationary object
If a large sputter target is used to coat large surface area substrates, then the substrate coverage is improved, but applying RF field uniformly across the target becomes difficult
Solution Approach 1:
The patent changes the electrical conductivity parameter of the target material from insulating to conductive, enabling the use of DC or pulsed-DC sputtering power sources instead of RF power sources. This eliminates the standing wave effects and field uniformity issues associated with RF sputtering of large targets, allowing uniform deposition across large substrate areas.
3Reliability
If Li3PO4 target is used for sputtering, then the deposited layer has the desired insulating properties, but the target itself is dielectric requiring RF alternating field which reduces sputter rate and increases complexity
Solution Approach 1:
The patent changes the electrical conductivity parameter of the target material from insulating (10^14 Ω·cm for Li3PO4) to conductive (≤1000 Ω·cm for carbon-doped Li3PO4). This enables the use of DC or pulsed-DC sputtering which provides higher sputter rates compared to RF sputtering, while the final deposited LiPON layer maintains its desired high electronic resistivity through the removal of carbon during the sputtering process.
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 facilitates uniform deposition of electrically insulating LiPON layers on large substrates using AC or DC sputtering, reducing the need for frequent target replacement and enhancing deposition efficiency.
Implementation Method 1
a plasma is generated in a low pressure chamber in which an inert gas such as argon, and/or a reactive gas such as oxygen or nitrogen is present, and a negative voltage is applied on a so called 'sputter target'... The gas atoms can be ionized, and the sputter target is bombarded by the gas ions, so that atoms are freed from the sputter target, and move to the substrate, where they are deposited.
Implementation Method 2
The gas atoms can be ionized, and the sputter target is bombarded by the gas ions
Implementation Method 3
Carbon in the target may, during sputtering, react with oxygen in the sputtering atmosphere to form CO and CO2, which may be pumped out of the system
Data Source
AI summary
A target for sputtering in mid-frequency AC sputtering processes, or DC sputtering processes includes a target material layer mainly including M-doped LixPOy, wherein x is from 2.5 to 3.5 and wherein y is from 2.5 to 4.5, wherein M represents up to 40 wt. % of the target material layer, and wherein M is least one chemical element from groups 13 to 15 of the periodic table, wherein M is selected for providing electrical conductivity to the target material layer such that an electrical resistivity of the target material layer is at most 1000 Ω·cm at room temperature, and wherein the target material layer has a lamellar structure consisting of microscopic splats of material.