Asymmetrical detector design and methodology

• US 9,418,819 B2
• Filed: 09/03/2014
• Issued: 08/16/2016
• Est. Priority Date: 09/06/2013
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation (KLA Corporation)
• Original Assignee: KLA-Tencor Corporation (KLA Corporation)
• Inventors: Gerling, John, Plettner, Tomas, Nasser-Ghodsi, Mehran
• Primary Examiner(s): IPPOLITO, NICOLE MARIE
• Application Number:
  US14/476,537
• Publication Number:
  US 20150069234A1
• Time in Patent Office: 713 Days
• Field of Search: 250/396.R, 250/397, 250/305, 250/306, 250/309, 250/310, 250/311, 250/492.1, 250/492.2, 250/492.3
• US Class Current: 1/1
• CPC Class Codes: H01J 2237/2446 Position sensitive detectors
• CPC Class Codes: H01J 2237/28 Scanning microscopes
• CPC Class Codes: H01J 37/244 Detectors; Associated components or circuits therefor
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

A charged particle detection device has an active portion for configured to produce a signal in response secondary charged particles emitted from a sample landing on the active portion. The active portion is shaped to accommodate an expected asymmetric pattern of the secondary charged particles at a detector. This abstract is provided to comply with rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Claims

1. A charged particle detection device, comprising:

a detector having an active portion and an inactive portion formed on a surface of a substrate, the surface being divided into the active portion and the inactive portion, whereby the active portion and the inactive portion make up an entirety of the surface of the substrate, wherein only the active portion is configured to produce a signal in response to secondary charged particles emitted from a sample landing on the active portion, wherein the substrate is symmetric with respect to an axis through a central aperture and wherein the active portion is asymmetric with respect to the axis to, accommodate an estimated axially asymmetrical distribution of the secondary particles at the detector with respect to a beam axis of a charged particle beam optical system.

2. The device of claim 1, wherein the active portion is sector-shaped.

3. The device of claim 1, further comprising a metallization layer on portions of the substrate other than the active portion, wherein the metallization layer is formed as an integral part of the device.

4. The device of claim 1, wherein the charged particle detection device is a diode device and wherein the active portion includes a junction and a depletion region.

5. The device of claim 1, wherein the charged particle detection device is a PN junction, PIN junction, CMOS detector, CCD, silicon-based/III-V detector, multi-channel plate, avalanche photodiode and/or Schottky diode.

6. The device of claim 1, further comprising an aperture in the detection device.

7. The device of claim 6, wherein the aperture is formed through the substrate at an axis of symmetry of the substrate.

8. The device of claim 7, wherein the aperture is surrounded by an inactive area, wherein the aperture and the inactive area are sized to keep signal losses due to clipping of detection of the secondary charged particles to less than 1%.

9. The device of claim 1, wherein the active portion is single sector-shaped region of the surface of the substrate.

10. A charged particle optical system, comprising:

a charged particle optical column configured to collect charged particles from a sample and image the charged particles onto a detector, wherein the detector has an active portion and an active portion formed on a surface of a substrate, the surface being divided into the active portion and the inactive portion, whereby the active portion and the inactive portion make up an entirety of the surface of the substrate, wherein the active portion is configured to produce a signal in response to secondary charged particles emitted from a sample landing on the active portion, wherein the substrate is symmetric with respect to an axis through a central aperture and wherein the active portion is asymmetric with respect to the axis to accommodate an estimated axially asymmetrical distribution of the secondary particles at the detector with respect to a beam axis of a charged particle beam optical column.

11. The system of claim 10, further comprising a source configured to emit a primary beam of energetic particles that impinge on the sample.

12. The system of claim 11, wherein system is configured to perform a line scan of the primary beam across the sample in a first direction in conjunction with translation of the sample in a second direction that is different from the first direction.

13. The system of claim 12, further comprising an image generator configured to produce an image of the sample from a signal produced by the detector in conjunction with translation of the sample in a second direction that is different from the first direction.

14. The system of claim 10, wherein the charged particle optical system is a scanning electron microscope (SEM) system, wherein the system further includes an electron source configured to emit primary electrons, and wherein the charged particle optical column is configured to direct the primary electrons onto the sample.

15. The system of claim 14, wherein the detector is located between the electron source and an end of the charged particle optical column that is closest to the sample, wherein the detector includes an aperture configured to allow at least a portion of the primary electrons to pass through the detector towards the target.

16. The system of claim 15, wherein the aperture is surrounded by an inactive area, wherein the aperture and the inactive area are sized to keep signal losses due to clipping of detection of the secondary charged particles to less than 1%.

17. The system of claim 10, wherein the charged particle optical system is a focused ion beam system, ultraviolet photoelectron spectroscopy (UPS) system, X-ray photoelectron spectroscopy (XPS) system, auger electron spectroscopy (AES) system, and/or Secondary Ion Mass Spectroscopy (SIMS) system.

18. The system of claim 10, wherein the detector further comprises a metallization layer on portions of the detector other than the active portion, wherein the metallization layer is formed as an integral part of the detector.

19. The system of claim 10, wherein the detector is a diode device having a junction and a depletion region.

20. The system of claim 10, wherein the active portion is single sector-shaped region of the surface of the substrate.