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US 6,721,036 B2Granted
Lithographic apparatus, device manufacturing method, and device manufactured thereby
AssigneeASML Netherlands B.V.
InventorsArie C. Scheiberlich, Menno Fien, Evert H. J. Draaijer
Life of this patent
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Abstract
On-the-Fly leveling in a lithographic apparatus is conducted using a setpoint derived by filtering the output of the combination of the output of a level sensor and another position sensor (LVDT or IFM). The level sensor may include look-ahead. The filter may be a low pass filter to cut-off level variations of wavelength shorter than the width of the slit during a scanning exposure. The filter may also be selected to reduce cross-talk between tilt movements and horizontal displacements.
Claims17
A lithographic projection apparatus comprising:
- a radiation system for supplying a projection beam of radiation;
- a support structure for holding patterning structure, the patterning structure serving to pattern the projection beam according to a desired pattern;
- a substrate table for holding a substrate;
- a projection system for projecting the patterned beam onto a target portion of the substrate;
- a level sensor for measuring at least one of a perpendicular position and tilt about at least one parallel axis of a surface of an object held by one of the support structure and the substrate table, and generating a position signal indicative thereof, perpendicular referring to a direction substantially perpendicular to the said surface and parallel referring to a direction substantially parallel to said surface;
- a servo system responsive to said position signal for moving said object to a desired position;
- and
- a filter connected between said level sensor and said servo system for filtering said position signal, the filter having a transfer function representative of a difference between an actual measurement of the level sensor and an ideal measurement of the level sensor.
5 more elements
A method of manufacturing a device comprising:
- providing a substrate that is at least partially covered by a layer of radiation-sensitive material;
- providing a projection beam of radiation;
- patterning the projection beam to produce a pattern in its cross-section;
- measuring at least one of a perpendicular position and tilt about at least one parallel axis of a surface of an object with a level sensor and generating a position signal indicative thereof, perpendicular referring to a direction substantially perpendicular to the said surface and parallel referring to a direction substantially parallel to said surface;
- projecting the patterned beam of radiation onto a target portion of the layer of radiation-sensitive material while operating a servo system responsive to said position signal to maintain said object at said desired position;
- and
- filtering said position signal to form a filtered position signal using a filter transfer function representative of a difference between an actual measurement of the level sensor and an ideal measurement of the level sensor before it is used by a servo system to control the position of the object.
4 more elements
A lithographic projection apparatus comprising:
- a radiation system for supplying a projection beam of radiation;
- a support structure for holding patterning structure, the patterning structure serving to pattern the projection beam according to a desired pattern;
- a substrate table for holding a substrate;
- a projection system for projecting the patterned beam onto a target portion of the substrate;
- a level sensor for measuring at least one of a perpendicular position and tilt about at least one parallel axis of a surface of an object held by one of the support structure and the substrate table, and for generating a position signal as a function of time indicative thereof, perpendicular referring to a direction substantially perpendicular to the said surface and parallel referring to a direction substantially parallel to said surface;
- a servo system responsive to said position signal for moving said object to a desired position;
- and
- a filter for correcting the transfer function of the level sensor wherein the filter is, arranged for filtering said position signal in the time domain.
5 more elements
A method of manufacturing a device comprising:
- providing a substrate that is at least partially covered by a layer of radiation-sensitive material;
- providing a projection beam of radiation;
- patterning the projection beam to produce a pattern in its cross-section;
- measuring at least one of a perpendicular position and tilt about at least one parallel axis of a surface of an object with a level sensor and generating a position signal as a function of time indicative thereof, perpendicular referring to a direction substantially perpendicular to the said surface and parallel referring to a direction substantially parallel to said surface;
- projecting the patterned beam of radiation onto a target portion of the layer of radiation-sensitive material while operating a servo responsive to said position signal to maintain said object at said desired position;
- and
- filtering said position signal in the time domain by using a filter transfer function for correcting the transfer function of the level sensor before it is used by said servo system to control the position of the object.
4 more elements
Dependencies are inferred from the claim text.