Ion Milling Stage Motion for Redeposition-Free Battery Cross Sections
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Solution Overview
Problem
During cross-section processing of all-solid-state batteries using an ion milling device, redeposition of conductive particles forms a conductive film that can short-circuit the electrodes, preventing structural and physical property evaluation.
Innovation Solution
An ion milling device with a sample stage that performs a swing operation and sliding operation, alternating between milling and removing redeposited particles to prevent the formation of a conductive redeposition film, using a control device to manage these operations and set conditions for effective particle removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion beam irradiation is performed for cross-section processing, then surface smoothing is achieved, but redeposition of conductive particles forms a conductive film that causes short circuits
Solution Approach 1:
The patent applies periodic action by alternating between ion beam irradiation (milling mode) and stage movement (transport mode) in cycles. During milling mode, the ion beam smooths the surface; during transport mode, the stage moves to a new position allowing redeposited particles to be removed from the processed area. This periodic alternation prevents continuous particle accumulation that would form conductive films, thereby maintaining electrical insulation while achieving surface smoothness.
Solution Approach 2:
The patent extracts the harmful redeposited particles from the processing area by moving the stage to a new position during transport mode. This separation removes the accumulated conductive particles from the vicinity of the processed cross-section, preventing them from forming continuous conductive films that would cause short circuits between electrodes.
2Productivity
If ion beam irradiation time is increased to improve processing depth, then milling efficiency increases, but particle redeposition and short circuit risk increase
Solution Approach 1:
The patent implements periodic action by cycling between milling mode (ion beam irradiation) and transport mode (stage movement to new position). This periodic interruption of continuous irradiation prevents excessive particle accumulation during prolonged processing, allowing the system to maintain high milling efficiency while controlling redeposition film thickness through periodic removal of processed areas.
Solution Approach 2:
The patent introduces a temporal dimension to the processing by alternating between milling and transport modes over time. This dimensional change allows the system to accumulate sufficient milling depth while periodically removing redeposited particles through stage movement, thereby managing particle accumulation without sacrificing overall productivity.
3Area of stationary object
If multi-point milling is performed to process multiple areas, then processing coverage increases, but redeposition on previously processed surfaces occurs
Solution Approach 1:
The patent applies periodic action by alternating between milling mode (processing current area) and transport mode (moving to next area). This periodic cycle ensures that when the ion beam processes a new area, previously processed surfaces have been temporarily removed from the particle accumulation zone, reducing redeposition on already milled surfaces and maintaining surface cleanliness across multiple processed areas.
Solution Approach 2:
The patent employs dynamics by making the stage position dynamic and adjustable during processing. The stage can be moved to different positions between milling operations, creating a dynamic processing system that adapts to multi-point milling requirements. This dynamic positioning prevents static particle accumulation on previously processed surfaces, maintaining manufacturing precision across multiple areas.
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 effectively reduces the occurrence of short circuits due to redeposition films, allowing for accurate structural and physical property evaluation of all-solid-state batteries.
Implementation Method 1
An ion milling device irradiates a surface or a cross section of a sample (for example, metals, semiconductors, glasses, and ceramic) with an unfocused ion beam (Ar ion or the like) accelerated to several kV, and flicks atoms on the surface of the sample without stress due to a sputtering phenomenon, thereby obtaining a smooth processed surface.
Implementation Method 2
When the sample chamber is evacuated and then the sample is irradiated with the ion beam from the ion source, fine particles that are flicked (sputtered) from an ion beam irradiation surface of the sample or another structure (for example, the sample holder or the sample stage) adhere to a vicinity of the ion beam irradiation surface of the sample. This is referred to as redeposition.
Data Source
AI summary
The invention provides an ion milling device capable of cross-sectional milling on an all-solid-state battery while reducing an occurrence of a short circuit due to a redeposition film. The ion milling device includes a sample stage 5 on which a sample 8 is placed, an ion source 1 configured to emit an unfocused ion beam 4 toward the sample, a stage controller 6 configured to cause the sample stage to perform a swing operation centered on a swing axis S0 set to be orthogonal to an ion beam center B0 of the ion beam, and cause the sample stage to perform a sliding operation along a line of intersection between a plane (YZ plane) including the ion beam center and perpendicularly intersecting the swing axis and a sample placement surface of the sample stage, in which the stage controller causes, in a first mode operation, the sample stage to perform the swing operation and the ion source to emit the ion beam to mill the sample, and causes in a second mode operation, the sample stage to perform the sliding operation and the ion source to emit the ion beam to remove sputter particles adhered again to the sample in the first mode operation.