Miniature Electron Beam Column With MEMS Lens Alignment
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Solution Overview
Problem
Conventional electron beam column technologies face challenges in achieving high-resolution, high-throughput, and accurate defect detection in semiconductor manufacturing due to limitations in alignment accuracy and stray fields, particularly in miniature columns used for semiconductor inspection.
Innovation Solution
The integration of silicon MEMS technology with magnetostatic lenses and the use of mu metal shielding to create a miniature electron beam column with precise alignment and reduced aberration, enabling high-resolution and high-throughput inspection by focusing electron beams effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional machining with permanent magnets is used to construct electron beam columns, then high throughput inspection is achieved, but alignment accuracy deteriorates
Solution Approach 1:
The column is divided into multiple silicon layers (e.g., 10-20 layers) that are processed separately using silicon MEMS technology, with each layer containing specific optical elements. This segmentation allows parallel processing and precise lithographic alignment while maintaining compact size for high throughput inspection
Solution Approach 2:
The patent replaces conventional mechanical machining and permanent magnet assembly with silicon MEMS fabrication processes. Lithography and silicon-based microfabrication techniques provide sub-micron alignment accuracy, eliminating the alignment errors inherent in mechanical machining while maintaining compact column dimensions
2Measurement precision
If silicon lens-stacks with permanent magnets are used, then high resolution is achieved, but operating conditions are limited
Solution Approach 1:
The patent employs electrostatic lenses with adjustable voltages instead of fixed permanent magnets, allowing dynamic control of focal length and beam parameters. This enables the same column to operate under multiple conditions (different accelerating voltages, focal lengths, and beam energies) without physical reconfiguration
Solution Approach 2:
The silicon-based electrostatic lens design provides multi-functional capability, serving as condenser, objective, and projector lenses through voltage control. This universal design replaces multiple specialized magnetic components, expanding operating flexibility while maintaining high resolution through precise electrostatic field control
3Manufacturing precision
If all-silicon MEMS technology is used to construct columns, then alignment accuracy is improved, but stray fields are not effectively managed
Solution Approach 1:
The patent extracts and removes stray magnetic fields from the system by eliminating permanent magnets entirely. Instead, it uses electrostatic fields generated by charged silicon elements, which do not produce stray magnetic fields that would interfere with detector electronics or require complex shielding
Solution Approach 2:
The patent introduces electrostatic fields as an intermediary mechanism to achieve beam control without magnetic fields. High-voltage electrodes in the silicon structure create controlled electric fields that focus and steer electrons without generating harmful magnetic stray fields, eliminating the need for mu-metal shielding
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 provides high-accuracy and high-resolution electron beam inspection with reduced distortion, enabling efficient detection of smaller defects in semiconductor wafers, overcoming the limitations of conventional machining and electrostatic columns.
Implementation Method 1
The magnetostatic objective lens is configured to focus an electron beam from the electron source as it passes through the aperture
Implementation Method 2
stray fields caused by the magnetostatic objective lens are negated using a high mu metal strategically placed around the device
Data Source
AI summary
A miniature electron beam column in combination with magnetostatic lenses to produce very high-performance miniature electron or ion beam columns. Silicon-based electron optical components provide high-accuracy formation and alignment of critical optical elements and the magnetic lenses provide low-aberration focusing or condensing elements. Accurate assembly of the silicon and magnetic components is achievable via the multilayered assembly techniques and allows for achieving high performance.