Charged particle guide

• US 7,135,678 B2
• Filed: 07/09/2004
• Issued: 11/14/2006
• Est. Priority Date: 07/09/2004
• Status: Active Grant

• Current Assignee: DCG Systems Incorporated (Thermo Fisher Scientific Incorporated)
• Original Assignee: Credence Systems Corporation (COHU Incorporated)
• Inventors: Lundquist, Theodore R., Wang, Qinsong Steve, Miau, Tzong Tsong
• Primary Examiner(s): Wells, Nikita
• Application Number:
  US10/887,800
• Publication Number:
  US 20060006329A1
• Time in Patent Office: 858 Days
• Field of Search: None
• US Class Current: 250/310
• CPC Class Codes: H01J 2237/2448 Secondary particle detectors
• CPC Class Codes: H01J 37/244 Detectors; Associated components or circuits therefor
• CPC Class Codes: H01J 37/3005 Observing the objects or the point of impact on the object

Abstract

A charged particle guide adapted to be coupled with a charged particle detector, such as a secondary electron detector. The charged particle guide, in one example, comprising two wires extending from the charged particle detector toward a source of charged particles, such as secondary electrons emitted from an IC upon application of a focused ion beam. Upon application of a bias voltage, the charged particle guide introduces a collecting electric field that attracts charged particles and directs the charged particles to the charged particles detector.

Claims

1. A charged particle detector assembly comprising:

a charged particle detector;

a first elongate member coupled with the charged particle detector;

a second elongate member coupled with the charged particle detector;

the first and the second elongate members extending away from the charged particle detector; and

at least one electrical connection point arranged to supply at least one bias voltage to the first and the second elongate members; and

wherein

the first and the second elongate members each comprise a wire.

2. The charged particle detector assembly of claim 1 wherein the charged particle detector comprises a secondary electron detector.

3. The charged particle detector assembly of claim 2 wherein the secondary electron detector comprises a scintillator.

4. The charged particle detector assembly of claim 3 wherein the secondary electron detector comprises a ring arranged circumferentially about the scintillator, and wherein the first elongate member and the second elongate member are electrically coupled with the ring.

5. The charged particle detector assembly of claim 4 wherein the scintillator defines a disk shape defining an axis.

6. The charged particle detector assembly of claim 5 wherein the first elongate member and the second elongate member are coupled with the ring and each define a first section extending from the secondary electron detector generally parallel with the axis of the scintillator.

7. The charged particle detector assembly of claim 6 wherein the first and the second elongate member each define a second section electrically coupled with the first section, the second section extending toward the axis of the scintillator.

8. The charged particle detector assembly of claim 7 wherein the first and second elongate members each define a third section electrically coupled with the second section, the third section extending toward the axis of the scintillator at less an angle than the second section.

9. The charged particle detector assembly of claim 8 wherein the first and second elongate members each define a fourth section electrically coupled with the third section, the fourth sections extending substantially parallel to each other and further extending at an angle with respect to the axis of the scintillator.

10. The charged particle detector assembly of claim 1 wherein the wire is of a material selected from the group comprising stainless steel, Ni, Cr, Pd, and Pt.

11. The charged particle detector assembly of claim 1 further comprising:

at least one additional elongate member coupled with the charged particle detector;

the first, the second, and the at least one additional elongate member extending from the charged particle detector; and

the at least one electrical connection point arranged to supply the at least one bias voltage to the first, the second, and the at least one additional elongate member.

12. The charged particle detector assembly of claim 1 wherein the first elongate member and the second elongate member are electrically insulated from the charged particle detector.

13. The charged particle detector assembly of claim 12 further comprising a first electrical connection adapted to supply a first bias voltage to the charged particle detector and a second electrical connection adapted to supply a second bias voltage to the first and the second elongate members.

14. The charged particle detector assembly of claim 13 wherein the first bias voltage is different than the second bias voltage.

15. The charged particle detector of claim 13 where the second voltage is less than the first voltage.

16. The charged particle detector of claim 15 wherein the first and second voltages are positive to create a first positive collecting electrical field and a second positive collecting field to attract secondary electrons emitted from a sample.

17. The charged particle detector assembly of claim 1 wherein the first elongate member is electrically isolated from the second elongate member and wherein the at least one electrical connection point comprises a first electrical connection to provide a first bias voltage to the first elongate member and a second electrical connection to provide a second bias voltage to the second elongate member.

18. The charged particle detector assembly of claim 1 wherein the charged particle detector assembly is adapted for use with a charged particle tool having a platform for supporting a sample and wherein the charged particle detector is arranged proximate to the platform.

19. The charged particle detector of claim 18 wherein the first and second elongate members are arranged to introduce a collecting electric field proximate the sample supported on the platform.

20. The charged particle detector of claim 18 wherein the first and second elongate members are arranged proximate the platform for collection of secondary charged particles.

21. The charged particle detector of claim 1 wherein the first elongate member and second elongate member are conductive and whereby the bias voltage generates a collection electrical field adapted to attract charged particles to the charged particle detector.

22. A charged particle detector assembly comprising:

means for detecting charged particles;

a first means for attracting charged particles;

a second means for attracting charged particles;

a means for electrically connecting the first means for attracting charged particles with the second means for attracting charged particles; and

wherein

the first means of attracting charged particles includes a first wire extending from the means for detecting charged particles and the second means for attracting charged particles includes a second wire extending away from the means for detecting charged particles.