Method and apparatus for reducing substrate edge effects in electron lenses

• US 20040149906A1
• Filed: 06/20/2003
• Published: 08/05/2004
• Est. Priority Date: 01/30/2003
• Status: Active Grant

• Current Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Original Assignee: Kla-Tencor Technologies Corporation (KLA Corporation)
• Inventors: Mankos, Marian, Adler, David L.
• Granted Patent: US 6,903,338 B2
• Time in Patent Office: Days
• US Class Current: 250/310
• CPC Class Codes: H01J 2237/153 Correcting image defects, e.g. stigmators
• CPC Class Codes: H01J 37/20 Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
• CPC Class Codes: Y10T 428/12528 Semiconductor component

Abstract

One embodiment disclosed pertains to a method for inspecting a substrate. The method includes inserting the substrate into a holding place of a substrate holder, moving the substrate holder under an electron beam, and applying a voltage to a conductive element of the substrate holder. The voltage applied to the conductive element reduces a substrate edge effect. Another embodiment disclosed relates to an apparatus for holding a substrate that reduces a substrate edge effect. The apparatus includes a holding place for insertion of the substrate and a conductive element. The conductive element is positioned so as to be located within a gap between an edge of the holding place and an edge of the substrate.

Claims

1. A method for inspecting a substrate, the method comprising:

inserting the substrate into a holding place of a substrate holder;

moving the substrate holder under an electron beam; and

applying a voltage to a conductive element of the substrate holder,

wherein the voltage applied to the conductive element reduces a substrate edge effect.

2. The method of claim 1, wherein the voltage applied to the conductive element depends upon a gap size between an edge of the substrate and an edge of the holding place.

3. The method of claim 2, further comprising:

determining the gap size as the substrate holder moves under the electron beam.

4. The method of claim 1, further comprising:

setting the substrate into a predetermined position within the holding place.

5. The method of claim 4, wherein the voltage applied to the conductive element depends on which portion of the substrate holder is currently under the electron beam.

6. The method of claim 1, further comprising:

performing a calibration run to determine a voltage function to apply to reduce the substrate edge effect.

7. The method of claim 1, wherein the moving is continuous.

8. The method of claim 7, further comprising:

detecting scattered electrons using a time-delayed integrating detector.

9. An apparatus for holding a substrate that reduces a substrate edge effect, the apparatus comprising:

a holding place for insertion of the substrate; and

a conductive element positioned so as to be located within a gap between an edge of the holding place and an edge of the substrate.

10. The apparatus of claim 9, wherein the conductive element is electrically isolated from the substrate.

14. The apparatus of claim 9, wherein the apparatus comprises a wafer holder, and wherein the substrate comprises a semiconductor wafer.

15. The apparatus of claim 14, wherein the conductive element comprises a ring.

16. The apparatus of claim 15, further comprising:

at least one insulating element supporting the ring.

17. The apparatus of claim 16, further comprising:

a variable power supply and conductive mechanism for applying a voltage to the ring.

11. The apparatus of claim 11, further comprising:

at least one insulating element supporting the conductive element.

12. The apparatus of claim 11, further comprising:

a power supply and conductive mechanism for applying a voltage to the conductive element.

13. The apparatus of claim 12, wherein the voltage applied is variable and dependent on a size of the gap.

18. A system for inspecting semiconductor wafers, the system comprising:

a mechanism for moving a wafer holder under an electron beam; and

means for reducing a wafer edge effect,

wherein the wafer edge effect depends upon a size of a gap between an edge of the wafer and an edge of the wafer holder.

19. The system of claim 18, wherein the means for reducing the wafer edge effect comprises:

a conductive element of the wafer holder to which a variable voltage is applied.

20. The system of claim 19, wherein the conductive element is located between the edge of the wafer and the edge of the wafer holder.