Sample pre-charging methods and apparatuses for charged particle beam inspection

1. An apparatus comprising:

an electron source configured to emit an electron beam along a primary beam axis of the apparatus;

a condenser lens configured to cause the electron beam to concentrate around the primary beam axis;

an aperture;

a first multi-pole lens; and

a second multi-pole lens,

wherein the first multi-pole lens is downstream with respect to the condenser lens and upstream with respect to the second multi-pole lens, and

wherein the second multi-pole lens is downstream with respect to the first multi-pole lens and upstream with respect to the aperture, and

wherein the first and the second multi-pole lenses are configured to adjust a current of the electron beam to be incident on a sample by adjusting a portion of the electron beam passing through the aperture.

2. The apparatus of claim 1 , further comprising a scanning deflector configured to scan the beam relative to a sample.

3. The apparatus of claim 1 , further comprising an objective lens configured to focus the beam onto a sample.

4. The apparatus of claim 1 , further comprising a third multi-pole lens and a fourth multi-pole lens,

wherein the third multi-pole lens is downstream with respect to the aperture, and

wherein the fourth multi-pole lens is downstream with respect to the third multi-pole lens.

5. The apparatus of claim 1 , wherein the first multi-pole lens and the second multi-pole lens are electrostatic lenses.

6. The apparatus of claim 1 , wherein the first multi-pole lens and the second multi-pole lens each have at least four poles.

7. The apparatus of claim 6 , wherein the poles each have a cross-sectional shape of a section of a ring.

8. The apparatus of claim 6 , wherein the poles are prismatic or cylindrical.

9. The apparatus of claim 6 , wherein each of the poles is separated from its neighbors by a gap or by a dielectric.

10. The apparatus of claim 6 , wherein the poles are configured to have different electric voltages applied thereto.

11. The apparatus of claim 1 , wherein the first multi-pole lens is configured to stretch the electron beam in a first direction and to compress the electron beam in a second direction, and wherein the second multi-pole lens is configured to stretch the electron beam in the second direction and to compress the electron beam in the first direction.

12. A method using the apparatus of claim 1 , the method comprising: setting a beam of charged particles into a first configuration suitable for pre-charging a sample; pre-charging an area of the sample using the beam of charged particles in the first configuration; setting the beam of charged particles into a second configuration suitable for imaging the sample; and imaging the area using the beam of charged particles in the second configuration.

13. The method of claim 12 , wherein setting the beam into the first configuration comprises energizing the first multi-pole lens and the second multi-pole lens.

14. A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions when executed by a computer implementing the method of claim 12 .

15. The apparatus of claim 1 , wherein the portion of the electron beam passing through the aperture is based on an activation state of the first multi-pole lens and the second multi-pole lens.

16. The apparatus of claim 15 , wherein the first multi-pole lens and the second multi-pole lens are configured to be activated such that substantially all of the electron beam is allowed to pass through the aperture.