Beam Separator with Adjustable Magnetic and Electrostatic Fields
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Solution Overview
Problem
Charged particle beam devices face challenges in maintaining imaging quality due to variations in secondary charged particle beam deflection angles caused by changes in primary beam landing energy, leading to aberrations and reduced throughput in semiconductor inspection processes.
Innovation Solution
A charged particle beam device incorporating a beam separator with both magnetic and electrostatic separation portions, allowing for adjustable deflection angles of primary and secondary charged particle beams by controlling electric and magnetic fields, ensuring consistent target axis alignment regardless of primary beam energy changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the landing energy of the primary charged particle beam is changed by changing the sample bias, then different imaging modes can be selected, but the secondary charged particle beam deflection angle varies causing aberrations and degraded imaging quality
Solution Approach 1:
The beam separator is designed with dynamically adjustable components including an electrostatic beam separator with variable voltage and a magnetic beam separator with variable current. This allows the separation angles for primary and secondary charged particle beams to be adjusted in real-time according to the primary beam energy, maintaining proper alignment across different imaging modes while enabling versatile operation
Solution Approach 2:
The system changes physical parameters of the beam separator (electrostatic voltage and magnetic current) to compensate for parameter changes in the primary beam (landing energy). By adjusting these parameters dynamically, the beam separator maintains optimal separation angles for both primary and secondary beams across different operating conditions, resolving the contradiction between adaptability and imaging quality
2Adaptability or versatility
If the primary charged particle beam energy is adjusted, then different imaging modes are enabled, but the secondary charged particle beam passes off-axis through the beam bender and optics causing aberrations
Solution Approach 1:
The system implements a feedback mechanism where the beam separator parameters (electrostatic voltage and magnetic current) are adjusted based on the detected primary beam energy. This feedback loop ensures that the secondary beam remains properly aligned with the optical axis by compensating for energy-induced deflection variations, maintaining reliability across different imaging modes
3Device complexity
If a fixed beam separator configuration is used, then the device structure is simple, but it cannot maintain proper beam alignment when primary beam energy changes
Solution Approach 1:
Rather than using a completely fixed configuration, the beam separator employs dynamically adjustable electrostatic and magnetic fields. This dynamic approach allows the system to cover a wide energy range while maintaining proper beam alignment, balancing the trade-off between device complexity and adaptability
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 enables efficient imaging in various modes with minimal hardware adjustments, maintaining high throughput and image quality by maintaining secondary charged particle beam alignment with the target axis across different primary beam energies.
Implementation Method 1
a magnetic beam separation portion (132) adapted for generating a magnetic field
Implementation Method 2
under the influence of the first magnetic field and the first electric field, leaves the beam separator at a second angle
Implementation Method 3
an electrostatic beam separation portion (131) adapted for generating an electric field
Implementation Method 4
under the influence of the first magnetic field and the first electric field, leaves the beam separator at a second angle
Data Source
AI summary
A method of operating a charged particle beam device is provided. The charged particle beam device includes a beam separator that defines an optical axis, and includes a magnetic beam separation portion and an electrostatic beam separation portion. The method includes generating a primary charged particle beam, and applying a voltage to a sample, the voltage being set to a first value to determine a first landing energy of the primary charged particle beam. The method further includes creating an electric current in the magnetic beam separation portion, the current being set to a first value to generate a first magnetic field, and applying a voltage to the electrostatic beam separation portion, the voltage being set to a first value to generate a first electric field. The method includes guiding the primary charged particle beam to the beam separator, wherein the primary charged particle beam enters the beam separator at a first angle relative to the optical axis and, under the influence of the first magnetic field and the first electric field, leaves the beam separator at a second angle relative to the optical axis. The method includes generating a secondary charged particle beam by impingement of the primary charged particle beam on the sample to which the voltage with the first value is applied, and separating the secondary charged particle beam from the primary charged particle beam in the beam separator, wherein the secondary charged particle beam enters the beam separator at a third angle relative to the optical axis and, under the influence of the first magnetic field and the first electric field, leaves the beam separator at a fourth angle relative to the optical axis. The first angle and the fourth angle are different. The method further includes applying the voltage to the sample, the voltage being set to a second value to determine a second landing energy of the primary charged particle beam, creating the electric current in the magnetic beam separation portion, the electric current being set to a second value to generate a second magnetic field, applying the voltage to the electrostatic beam separation portion, the voltage being set to a second value to generate a second electric field, guiding the primary charged particle beam to the beam separator, wherein the primary charged particle beam enters the beam separator at the first angle relative to the optical axis and, under the influence of the second magnetic field and the second electric field, leaves the beam separator at the second angle relative to the optical axis, generating the secondary charged particle beam by impingement of the primary charged particle beam on the sample to which the voltage with the second value is applied, and separating the secondary charged particle beam from the primary charged particle beam in the beam separator, wherein the secondary charged particle beam enters the beam separator at the third angle relative to the optical axis and, under the influence of the second magnetic field and the second electric field, leaves the beam separator at the fourth angle relative to the optical axis.