Third-order spherical aberration correction using multistage self-aligned quadrupole correction-lens systems.

Area of Science:

• Optics and Photonics
• Charged Particle Optics

Background:

• Spherical aberration limits resolution in probe-forming systems like electron beam lithography (EBL) and focused ion beam (FIB).
• Existing correction methods require complex configurations and high excitation levels.

Purpose of the Study:

• To propose novel multistage self-aligned quadrupole correction-lens systems for spherical aberration correction.
• To investigate the performance of six- and eight-stage systems compared to a four-stage system.

Main Methods:

• Development of multistage electrostatic quadrupole and aperture electrode systems.
• Simulation of optical properties using approximated potential functions from 3D potential distributions.
• Comparison of six- and eight-stage systems with a four-stage system.

Main Results:

• Six- and eight-stage systems automatically generate aligned octupole fields for aberration correction.
• Aperture aberration coefficients are significantly reduced in the six- and eight-stage systems.
• Effective spherical aberration correction is achieved with lower lens element excitation.

Conclusions:

• Multistage self-aligned quadrupole correction-lens systems offer a superior solution for spherical aberration in probe-forming instruments.
• These systems provide enhanced performance and efficiency, enabling higher resolution imaging and fabrication.