Exposure apparatus, exposure method and process for producing device

• US 20030058423A1
• Filed: 10/24/2002
• Published: 03/27/2003
• Est. Priority Date: 04/13/1999
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Wakamoto, Shinji
• Granted Patent: US 7,023,521 B2
• Time in Patent Office: Days
• US Class Current: 355/53
• CPC Class Codes: G03F 7/70358 Scanning exposure, i.e. relative movement of patterned beam and workpiece during imaging
• CPC Class Codes: G03F 9/7026 Focusing
• CPC Class Codes: G03F 9/7034 Leveling

Abstract

Disclosed is a step-and-scan exposure method improved in exposure at a periphery of a wafer. An area illuminated by an exposure beam is made to relatively scan a shot area positioned at the wafer periphery from the outside of the wafer to the inside. Predetermined measurement points of a sensor for detecting positional information of a wafer with respect to a focal position of a projection optical system in the direction of the optical axis of the projection optical system are made to relatively scan along with the illumination area of the exposure beam. Focus control is performed to make the wafer move in the direction of the optical axis when only part of the selected predetermined measurement positions reach the wafer, and leveling control is performed in addition to adjust the tilt of the wafer when all of the selected predetermined measurement positions reach the wafer.

Claims

1. An exposure apparatus making a mask and substrate move synchronously with respect to a projection optical system so as to transfer a pattern on the mask to the substrate,

said exposure apparatus comprising:

a sensor able to detect positional information of the substrate in a direction of the optical axis of the projection optical system at a plurality of measurement positions,

adjusting means of focusing control for adjusting a relative position in the direction of the optical axis between the substrate and an image plane of the projection optical system and leveling control for adjusting a relative tilt between said substrate and said image plane, and

a control switching means for switching control during scanning exposure of the substrate so as to perform only said focusing control when only part of selected predetermined measurement positions of the sensor are positioned inside an effective area of the substrate and so as to additionally perform leveling control when all the selected predetermined measurement positions are positioned inside the effective area of the substrate.

2. The exposure apparatus as set forth in claim 1, further comprising a determining means for determining selected predetermined measurement positions of the sensor based on which position on the substrate a shot area of the substrate is at.

3. The exposure apparatus as set forth in claim 1, which, when the shot area of the substrate is at the periphery of the substrate,

defines a length required for leveling control in a non-scanning direction perpendicular to a direction of synchronous movement of the substrate as L1 and a length of the shot area on the substrate in the non-scanning direction as L2,

hypothesizes, inside said shot area, a surface area S1 of a first rectangular shape having a side of a length of the length L1, having a first corner intersect with an edge of the substrate, and having an opposite corner of the first corner overlap with a corner of the shot area close to the center of the substrate,

hypothesizes, inside said shot area, a surface area S2 of a second rectangular shape having a side of a length of the length L2, having a second corner intersect with an edge of the substrate, and having an opposite corner of the second corner overlap with a corner of the shot area close to the center of the substrate, and

compares the surface area S1 of the first rectangular shape and the surface area S2 of the second rectangular shape and has the measurement positions positioned inside the larger surface area determined by the determining means as the selected predetermined measurement positions of the sensor.

4. The exposure apparatus as set forth in claim 1, wherein said leveling control is performed in only a non-scanning direction perpendicularly intersecting the direction of synchronous movement of the mask and substrate.

5. An exposure apparatus using an exposure beam to illuminate a substrate through a mask and projection optical system and making an illumination area of the exposure beam relatively scan the substrate so as to transfer a pattern on the mask to the substrate, said exposure apparatus comprising:

a detecting means for detecting Z-axial positional information along a direction substantially perpendicular to an image plane of the projection optical system at a plurality of measurement points set at positions in a predetermined relationship with respect to the illumination area and

a posture control means for controlling the posture of the substrate with respect to the image plane based on the Z-axial positional information during the scanning exposure,

the posture control means including a switching means for switching between a first control for performing only focusing control for said substrate with respect to said image plane and a second control for performing both focusing control and leveling control for said substrate with respect to said image plane in accordance with a relative positional relationship between the plurality of measurement points and the substrate during the scanning exposure.

6. An exposure method making a mask and substrate move synchronously with respect to a projection optical system so as to make an illumination area of an exposure beam passing through the projection optical system relatively scan a shot area on the substrate to expose the shot area, comprising the steps of:

making said illumination area of the exposure beam relatively scan a shot area positioned at a periphery of the substrate from the outside of the substrate to the inside,

performing only focusing control for adjusting a relative position in the direction of the optical axis between said substrate and the image plane of the projection optical system from when only part of selected predetermined measurement positions for detection of positional information of the substrate in the direction of the optical axis of the projection optical system are positioned inside an effective area of the substrate, and

performing additionally leveling control for adjusting a relative tilt between said substrate and said image plane from when all of the selected predetermined measurement positions are positioned inside the effective area of the substrate.

7. The exposure method as set forth in claim 6, further determining selected predetermined measurement positions of the sensor based on which position on the substrate a shot area of the substrate is at.

8. The exposure method as set forth in claim 7, which, when the shot area of the substrate is at the periphery of the substrate,

defines a length required for leveling control in a non-scanning direction perpendicular to a direction of synchronous movement of the substrate as L1 and a length of the shot area on the substrate in the non-scanning direction as L2,

hypothesizes, inside said shot area, a surface area S1 of a first rectangular shape having a side of a length of the length L1, having a first corner intersect with an edge of the substrate, and having an opposite corner of the first corner overlap with a corner of the shot area close to the center of the substrate,

hypothesizes, inside said shot area, a surface area S2 of a second rectangular shape having a side of a length of the length L2, having a second corner intersect with an edge of the substrate, and having an opposite corner of the second corner overlap with a corner of the shot area close to the center of the substrate, and

compares the surface area S1 of the first rectangular shape and the surface area S2 of the second rectangular shape and has the measurement positions positioned inside the larger surface area determined as the selected predetermined measurement positions.

9. The exposure method as set forth in claim 6, wherein during said leveling control, leveling control is performed in only a non-scanning direction perpendicularly intersecting the direction of synchronous movement of the mask and substrate.

10. An exposure method using an exposure beam to illuminate a substrate through a mask and projection optical system and making the illumination area of the exposure beam relatively scan the substrate so as to transfer a pattern on the mask to the substrate, said method comprising the steps of:

detecting Z-axial positional information along a direction substantially perpendicular to an image plane of the projection optical system at a plurality of measurement points set at positions in a predetermined relationship with respect to the illumination area and

controlling a posture of the substrate with respect to the image plane based on the Z-axial positional information during the scanning exposure,

the step of controlling the posture including a step of switching between a first control for performing only focusing control for the substrate with respect to said image plane and a second control for performing both focusing control and leveling control for the substrate with respect to the image plane based on relative positional relationship between the plurality of measurement points and the substrate during the scanning exposure.

11. The exposure method as set forth in claim 10, further including a step of obtaining Z-axial positional information of measurement points positioned in an effective area of said substrate based on relative positional information of said substrate and said plurality of measurement points during said scanning exposure.

12. The exposure method as set forth in claim 10, wherein said leveling control includes at least one of leveling control in a scanning direction of said substrate and leveling control in a non-scanning direction perpendicularly intersecting said scanning direction.

13. The exposure method as set forth in claim 10, which, when making said illumination area relatively scan a shot area positioned at a periphery of said substrate from an outside of the substrate to an inside, performs the first control until two measurement points separated by at least a predetermined length in said scanning direction or said non-scanning direction reach an effective area of said substrate and performs said second control from when said two measurement points reach said effective area.

14. A process for production of a device comprising the steps of:

making an illumination area of an exposure beam relatively scan a shot area positioned at a periphery of a substrate from the outside of the substrate to the inside,

performing only focusing control for adjusting a relative position in the direction of the optical axis between said substrate and an image plane of a projection optical system from when only part of selected predetermined measurement positions for detection of positional information of the substrate in the direction of the optical axis of the projection optical system are positioned inside an effective area of the substrate,

performing additionally leveling control for adjusting a relative tilt between said substrate and said image plane from when all of the selected predetermined measurement positions are positioned inside the effective area of the substrate, and

making a mask and substrate move synchronously with respect to the projection optical system so as to make an illumination area of the exposure beam passing through the projection optical system relatively scan a shot area on the substrate to expose the shot area and transfer the pattern of the mask on to the substrate.

15. A process for production of a device comprising the steps of:

detecting Z-axial positional information of a substrate along a direction substantially perpendicular to an image plane of the projection optical system at a plurality of measurement points set at positions in a predetermined relationship with respect to an illumination area,

controlling the posture of the substrate with respect to the image plane based on the Z-axial positional information during scanning exposure,

switching between a first control for performing only focusing control for the substrate with respect to said image plane and a second control for performing both focusing control and leveling control for the substrate with respect to the image plane-based on relative positional relationship between the plurality of measurement points and the substrate during the scanning exposure at the time of controlling the posture, and

using an exposure beam to illuminate the substrate through a mask and the projection optical system and making the illumination area of the exposure beam relatively scan the substrate so as to transfer a pattern on the mask to the substrate.

16. A process for production of an exposure apparatus for making a mask and substrate move synchronously with respect to a projection optical system so as transfer a pattern of the mask on to the substrate, comprising the steps of:

providing a sensor able to detect positional information of the substrate in the direction of the optical axis of the projection optical system at a plurality of measurement positions,

providing adjusting means for focusing control for adjusting a relative position in the direction of the optical axis between the substrate and an image plane of the projection optical system and leveling control for adjusting a relative tilt between said substrate and said image plane based on the a result of detection of the sensor, and

providing a control switching means for switching control during scanning exposure of the substrate so as to perform only said focusing control when only part of the selected predetermined measurement positions of the sensor are positioned inside an effective area of the substrate and so as to additionally perform leveling control when all the selected predetermined measurement positions are positioned inside the effective area of the substrate.

17. A process for production of an exposure apparatus using an exposure beam to illuminate a substrate through a mask and projection optical system and making an illumination area of the exposure beam relatively scan the substrate so as to transfer a pattern on the mask to the substrate, comprising the steps of:

providing a detecting means for detecting Z-axial positional information along a direction substantially perpendicular to an image plane of the projection optical system at a plurality of measurement points set at positions in a predetermined relationship with respect to the illumination area and

providing a posture control means for controlling the posture of the substrate with respect to the image plane based on the Z-axial positional information during the scanning exposure and including a switching means for switching during scanning exposure between a first control for performing only focusing control for said substrate with respect to said image plane and a second control for performing both focusing control and leveling control for said substrate with respect to the image plane based on a relative positional relationship between the plurality of measurement points and the substrate.