Method of determining a focus position for a substrate exposure process and substrate exposure apparatus capable of performing the same

• US 20070103663A1
• Filed: 10/31/2006
• Published: 05/10/2007
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Eun-Sung
• Granted Patent: US 7,697,113 B2
• Time in Patent Office: Days
• US Class Current: 355/55
• CPC Class Codes: G03F 7/70091 Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
• CPC Class Codes: G03F 9/7026 Focusing

Abstract

In a method of determining a focus position for a substrate exposure process and a substrate exposure apparatus capable of performing the same, a reticle having a light-transmitting region may be illuminated by an off-axis illumination light. A projected light, which is transmitted through the reticle and a projection optical system, may be detected by a light sensor disposed on a substrate stage. An intensity of the projected light measured at a light-receiving surface of the light sensor may vary in accordance with positions of the light-receiving surface. The focus position may be determined based on the variations in the intensity of the projected light.

Claims

1. A method of determining a focus position for a substrate exposure process comprising:

measuring an intensity of projected light at a projection plane, the intensity of the projected light having at least one peak;

measuring variations of the intensity and the at least one peak at the projection plane while moving the projection plane in an optical axis direction of the projected light; and

determining a focus position based on the variations of the intensity and the at least one peak.

2. The method of claim 1, further comprising:

illuminating a reticle having at least one light-transmitting region with an off-axis illumination light; and

focusing a projected light passing through the light-transmitting region onto the projection plane.

3. The method of claim 1, wherein the intensity of the projected light has a plurality of peaks and the focus position is determined as a position of the projection plane that corresponds to a minimum number of the plurality of peaks.

4. The method of claim 1, wherein the focus position is determined as a position of the projection plane that corresponds to a maximum peak value of the at least one peak.

5. The method of claim 1, wherein the off-axis illumination light has a pair of poles.

6. The method of claim 5, wherein the light-transmitting region extends in a direction substantially perpendicular to an arrangement direction of the pair of poles.

7. The method of claim 5, wherein the reticle has a plurality of light-transmitting regions arranged in substantially the same direction as an arrangement direction of the pair of poles.

8. The method of claim 7, wherein the plurality of light-transmitting regions each extend in a direction substantially perpendicular to the arrangement direction of the pair of poles.

9. The method of claim 8, wherein the focus position is determined as a position of the projection plane that corresponds to a minimum distance between outermost peaks of the measured intensity.

10. The method of claim 1, wherein the intensity of the projected light is measured by a light sensor disposed on a stage for supporting a substrate.

11. The method of claim 10, wherein the projection plane is a light-receiving surface of the light sensor.

12. A substrate exposure apparatus comprising:

an illumination optical system providing an off-axis illumination light;

a reticle stage supporting a reticle having at least one light-transmitting region,

the reticle being illuminated by the off-axis illumination light;

a projection optical system focusing projected light passing through the reticle;

a substrate stage moving in an optical axis direction of the projection optical system and a direction substantially perpendicular to the optical axis direction, the substrate stage having a substrate holder for holding a substrate;

a light sensor measuring an intensity of the projected light having at least one peak and variations of the intensity and the at least one peak in accordance with changes in a position of the substrate stage, the light sensor having a projection plane where the projected light is focused thereon; and

a focusing system for determining a focus position based on the variations of the intensity and the at least one peak.

13. The substrate exposure apparatus of claim 12, wherein the off-axis illumination light is a dipole illumination light having a pair of poles.

14. The substrate exposure apparatus of claim 13, wherein the light-transmitting region extends in a direction substantially perpendicular to an arrangement direction of the pair of poles.

15. The substrate exposure apparatus of claim 13, wherein the first reticle has a plurality of light-transmitting regions arranged in substantially the same direction as an arrangement direction of the pair of poles.

16. The substrate exposure apparatus of claim 15, wherein the light-transmitting regions extend in a direction substantially perpendicular to the arrangement direction of the pair of poles.

17. The substrate exposure apparatus of claim 12, wherein the reticle stage is configured to support another reticle and image patterns transcribed onto the substrate are varied by replacing the reticle with the another reticle.