Method for charging substrate to a potential

• US 20060054815A1
• Filed: 09/16/2004
• Published: 03/16/2006
• Est. Priority Date: 09/16/2004
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Bertsche, Kirk J., McCord, Mark A.
• Granted Patent: US 7,176,468 B2
• Time in Patent Office: Days
• US Class Current: 250/310
• CPC Class Codes: G21K 7/00 Gamma- or X-ray microscopes
• CPC Class Codes: H01J 2237/0045 using secondary electrons
• CPC Class Codes: H01J 2237/0048 Charging arrangements
• CPC Class Codes: H01J 37/026 Means for avoiding or neutralising unwanted electrical charges on tube components

Abstract

A surface of an insulating substrate is charged to a target potential. In one embodiment, the surface is flooded with a higher-energy electron beam such that the electron yield is greater than one. Subsequently, the surface is flooded with a lower-energy electron beam such that the electron yield is less than one. In another embodiment, the substrate is provided with the surface in a state at an approximate initial potential above the target potential. The surface is then flooded with charged particle such that the charge yield of scattered particles is less than one, such that a steady state is reached at which the target potential is achieved. Another embodiment pertains to an apparatus for charging a surface of an insulating is substrate to a target potential.

Claims

1. A method of charging a surface of an insulating substrate to a target potential, the method comprising:

flooding the surface with a higher-energy electron beam such that an electron yield is greater than one; and

subsequently flooding the surface with a lower-energy electron beam such that the electron yield is less than one.

2. The method of claim 1, wherein the higher-energy beam flooding is configured to have a landing energy greater than an energy at which the electron yield is one.

3. The method of claim 2, wherein an electrostatic field is created by applying a bias voltage between a lower bias electrode of a flood gun and the substrate during the higher-energy electron flooding.

4. The method of claim 3, wherein the surface charges to approximately a potential of the lower bias electrode during the higher-energy flooding.

5. The method of claim 4, wherein the potential of the lower bias electrode is more positive than the target potential.

6. The method of claim 1, wherein the lower-energy beam flooding is configured to have a landing energy less than an energy at which the electron yield is one, such that the surface charges negatively and reaches a steady state where the surface reflects incident electrons.

7. The method of claim 1, further comprising:

covering the surface sequentially by the higher-energy beam flooding and then by the lower-energy beam flooding.

8-11. -11. (canceled)

12. A process of charging a surface of an insulating substrate to a target potential, the process comprising:

performing a first flooding process to provide the substrate with the surface in a state at an approximate initial potential above the target potential;

after the first flooding process, performing a second flooding process to flood the surface with charged particle such that a charge yield of scattered particles is less than one;

reaching a steady state at which the surface achieves the target potential.

13. The process of claim 12, wherein the charged particles comprise electrons, and the scattered particles comprise scattered electrons.

14. The process of claim 12, wherein, at the steady state, the charged particles flooding the substrate are reflected from the substrate.

18. The process of claim 12, wherein the first flooding process is performed using electron beam flooding with an electron yield greater than one.

19. The process of claim 12, wherein the pre-charging is performed using ion beam bombardment.

22. The process of claim 12, wherein the insulating substrate comprises an insulating layer on a semiconductor wafer.

15-16. -16. (canceled)

17. (canceled)

20-21. -21. (canceled)

23-27. -27. (canceled)