Annular illumination method for charged particle projection optics

A method of aligning an E-beam with an aperture including:

• providing an E-beam,
• providing a shaping aperture means adapted for shaping an E-beam into a hollow E-beam,
• directing the E-beam through the shaping aperture means,
• providing deflection coils for deflecting the E-beam relative to the shaping aperture,
• varying the current to the alignment deflection coils,
• measuring the electrical current generated by electrons from the E-beam reaching the shaping aperture as a function of the current to the alignment deflection coils, and
• setting the current in the alignment deflection coils, to center the E-beam on the shaping aperture.

Apparatus for aligning a charged particle beam comprising:

• a hollow beam aperture means adapted for shaping a charged particle beam into a hollow charged particle beam,
• beam means producing a charged particle beam directed through the aperture means,
• deflection coils for deflecting the charged particle beam relative to the aperture,
• deflection current means for varying the current to the alignment deflection coils,
• measurement means for measuring the aperture electrical current generated by charged particles reaching the hollow beam aperture as a function of the current to the alignment deflection coils, and
• adjustment means for adjusting the current in the alignment deflection coils based on the aperture electrical current to center the charged particle beam on the hollow beam aperture.

Apparatus for aligning a E-beam comprising:

• a hollow beam aperture means adapted for shaping a E-beam into a hollow E-beam,
• beam means producing a E-beam directed through the aperture means,
• deflection coils for deflecting the E-beam relative to the aperture,
• deflection current means for varying the current to the alignment deflection coils,
• measurement means for measuring the aperture electrical current generated by electrons reaching the hollow beam aperture as a function of the current to the alignment deflection coils, and
• adjustment means for adjusting the current in the alignment deflection coils based on the aperture electrical current to center the E-beam on the hollow beam aperture.