Gaseous Ion Beam Cleaning for Needle Sample Surface Damage
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Solution Overview
Problem
The existing atom probe analysis methods often result in the formation of a damaged layer on the sample surface due to ion implantation during the processing of needle-shaped samples, which can affect the quality of the semiconductor samples.
Innovation Solution
A charged particle beam apparatus is designed with an electron beam irradiation unit, an ion beam irradiation unit, a detection unit, and a gaseous ion beam irradiation unit, where the sample is rotated to allow gaseous ion beams to remove implanted ions, preventing the formation of a damaged layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ion beams are used to process the sample into a needle shape, then the sample can be shaped efficiently, but implanted ions form a damaged layer on the sample surface
Solution Approach 1:
The patent converts the harmful effect of ion implantation into a beneficial cleaning process. By introducing a gaseous ion beam source that generates secondary ions, the previously harmful implanted ions are removed through sputtering erosion, transforming the damage into a purification mechanism that eliminates contaminants and implanted ions from the sample surface
Solution Approach 2:
The patent changes the physical and chemical parameters of the ion beam by introducing a gaseous ion beam source (e.g., cesium) with different properties from the original solid ion beam source. This parameter change allows the generation of secondary ions that effectively remove implanted ions through sputtering, while the low erosion rate preserves the sample integrity
2Ease of manufacture
If the sample surface is irradiated with ion beams, then the sample can be processed, but the implanted ions cannot be removed from the surface
Solution Approach 1:
The patent introduces a gaseous ion beam as an intermediary medium between the sample processing step and the final analysis. This intermediary beam serves dual purposes: it facilitates further processing while simultaneously removing implanted ions through secondary ion generation and sputtering, thus mediating between processing requirements and sample quality preservation
Solution Approach 2:
The patent changes the chemical composition and physical state parameters of the ion beam by using a gaseous ion source (e.g., cesium vapor) instead of a solid ion source. This parameter change enables the generation of secondary ions with appropriate mass and energy characteristics for effective sputtering removal of implanted ions while maintaining low erosion rates
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 solution effectively removes implanted ions over the entire sample surface, preventing damage and enabling the production of high-quality needle-shaped samples suitable for atom probe analysis with minimal influence on semiconductor materials.
Implementation Method 1
the gaseous ion beam irradiation unit irradiates the sample with the gaseous ion beams, and thus implanted ions which are implanted into the surface of the sample due to irradiation with the ion beams can be removed
Implementation Method 2
a detection unit configured to detect at least one of charged particles and X rays generated via the sample by the irradiation with the ion beams and electron beams
Implementation Method 3
a technique is known in which a needle-shaped sample is created from a thin film by using a focused ion beam (FIB)
Data Source
AI summary
A charged particle beam apparatus includes an electron beam irradiation unit that irradiates a sample with electron beams along a first irradiation axis. A rotation stage holds the sample and has a rotation axis in a direction perpendicular to the first irradiation axis. An ion beam irradiation unit irradiates the sample with ion beams along a second irradiation axis that is substantially parallel to the rotation axis to process the sample into a needle shape. A detection unit detects at least one of charged particles and X rays generated via the sample by the irradiation with the ion beams or the electron beams, and a gaseous ion beam irradiation unit irradiates the sample with gaseous ion beams. A control unit controls the apparatus to incrementally rotate the rotation stage repeatedly by a predetermined angle to rotate the rotation stage by 360° in conjunction with irradiating the entire surface of the needle-shaped sample in a circumferential direction with the gaseous ion beams to remove ions implanted during processing the sample by the ion beams.