Focused Ion Beam Vacuum Pad for Peripheral Substrate Processing
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Solution Overview
Problem
Existing scanning electron microscope systems require precise height level alignment between the retraction member and the sample to maintain a vacuum, leading to difficulties in processing areas near the substrate periphery without a large vacuum chamber.
Innovation Solution
A focused ion beam system with a differentially-pumped vacuum unit that includes exhaust grooves and a vacuum pad surrounding the substrate edge, allowing vacuum maintenance even when the unit partially falls out of the substrate edge, enabling processing near the substrate periphery without a large vacuum chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a large vacuum chamber is used to enable processing near the substrate periphery, then the processing area is expanded, but the system complexity and space requirements increase significantly
Solution Approach 1:
The vacuum system is segmented into multiple independent vacuum regions: a main vacuum chamber and a localized differentially-pumped vacuum unit. This allows the processing area to be expanded to the substrate periphery without requiring the entire chamber to be evacuated, thus avoiding the need for a large vacuum chamber while maintaining high vacuum conditions only where needed for processing.
Solution Approach 2:
High vacuum conditions are applied locally only to the processing region near the substrate periphery using the differentially-pumped vacuum unit, rather than maintaining high vacuum throughout the entire chamber. This localized approach enables peripheral processing while keeping the overall system compact and reducing the required vacuum chamber size.
2Reliability
If the height level of the retraction member is precisely aligned with the sample surface, then vacuum maintenance is improved, but the flexibility in positioning and the ease of operation are reduced
Solution Approach 1:
The differentially-pumped vacuum unit is designed with movable components including a retraction member that can be dynamically positioned at different height levels relative to the substrate surface. The system maintains reliable vacuum through active control of the vacuum pump and dynamic adjustment of the retraction member position, rather than relying on fixed precise alignment. This dynamic approach provides positioning flexibility while maintaining vacuum reliability through active management.
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
Enables processing over a wider area of the substrate without requiring strict height level control and maintaining a high vacuum, reducing the need for a large vacuum chamber and facilitating efficient ion beam operations.
Implementation Method 1
vacuum evacuation works to create a high vacuum inside the processing vacuum region
Implementation Method 2
the suction surface allows an input of air evacuated from a region between the suction surface and the head to maintain the high vacuum inside the processing vacuum region
Implementation Method 3
a focused ion beam optical system built in the chamber to emit a focused ion beam in a way that passes through the orifice
Data Source
AI summary
A focused ion beam system has a differentially-pumped vacuum unit and a focused ion beam column, comprising: a vacuum pad, of a porous material, with a suction surface exposed in a way that surrounds the outer edge of a substrate to be processed; a substrate support on which the substrate and vacuum pad are placed, and a vacuum pump for vacuum evacuation using the vacuum pad. The system provides an arrangement in which, while a head of the differentially-pumped vacuum unit partially falls out of the outer edge of the substrate, the suction surface allows an input of air evacuated from a region between the suction surface and the head, and the processing area on a substrate is expanded by allowing the processing with an ion beam to be performed even in the vicinity of the peripheral substrate surface without requiring a large vacuum chamber.