Lithographic apparatus and method for determining Z position errors/variations and substrate table flatness

A lithographic apparatus, comprising:

• an illumination system for providing a beam of radiation;
• a support structure for supporting a patterning device that imparts said beam radiation with a pattern in its cross-section;
• a substrate holder for holding a substrate having a target portion;
• a projection system for projecting said patterned beam onto said target portion of said substrate;
• a moveable object having at least one reference part that is moveable in a plane of movement relative to a base in which the actual movement of said reference part is limited to within an area bounded by a closed contour;
• and
• a measurement system for measuring displacement of said moveable object relative to a base along at least a first direction of measurement, said measurement system comprising:
• a planar element having a shape that is substantially similar to the closed contour shape of said bounded area;
• a sensor head configured to operatively cooperate with said planar element to determine displacement of said movable object, and
• wherein said planar element and said sensor head are arranged so that said sensor head is mounted to said reference part of said moveable object or said planar element is mounted to said base and said sensor head is mounted to said reference part of said moveable object.

A measurement system for measuring displacement of a moveable object relative to a base along six degrees of freedom, said measurement system comprising:

• at least three primary measurement units for measuring translational displacement of the moveable object relative to the base in a first direction;
• at least two secondary measurement units for measuring translational displacement of said moveable object relative to said base in a second direction differing from the first direction,
• at least one tertiary measurement unit for measuring translational displacement of the moveable object relative to the base in a third direction differing from the first direction and from the second direction and extending at an angle relative to a directional plane that is defined by a combination of the first direction and the second direction,
• wherein said measurement units are located at known relative positions,
• wherein each of said measurement unit comprises a sensor head and a planar element in which said sensor head is configured to transmit a beam to said planar element and said planar element is configured to reflect said beam to said sensor head in order to measure translational displacement of said sensor head relative to said planar element,
• wherein said measurement units are combined into at least three measurement assemblies, each of said three measurement assemblies comprising a primary measurement unit and at least one of a secondary measurement unit and a tertiary measurement unit, and
• wherein the directions associated with said measurement units of a single measurement assembly together define a measurement plane, each of the planar elements of a single measurement assembly being arranged parallel to said measurement plane.

A lithographic apparatus, comprising:

• an illumination system for providing a beam of radiation;
• a support structure for supporting a patterning device that imparts said beam radiation with a pattern in its cross-section;
• a substrate holder for holding a substrate having a target portion;
• a projection system for projecting said patterned beam onto said target portion of said substrate;
• a moveable object that is moveable relative to a base;
• and
• a measurement system for measuring displacement of said moveable object relative to said base along six degrees of freedom, said measurement system comprising:
• at least three primary measurement units for measuring translational displacement of the moveable object relative to the base in a first direction;
• at least two secondary measurement units for measuring translational displacement of said moveable object relative to said base in a second direction differing from the first direction,
• at least one tertiary measurement unit for measuring translational displacement of the moveable object relative to the base in a third direction differing from the first direction and from the second direction and extending at an angle relative to a directional plane that is defined by a combination of the first direction and the second direction,
• wherein said measurement units are located at known relative positions,
• wherein each of said measurement unit comprises a sensor head and a planar element in which said sensor head is configured to transmit a beam to said planar element and said planar element is configured to reflect said beam to said sensor head in order to measure translational displacement of said sensor head relative to said planar element,
• wherein said measurement units are combined into at least three measurement assemblies, each of said three measurement assemblies comprising a primary measurement unit and at least one of a secondary measurement unit and a tertiary measurement unit, and
• wherein the directions associated with said measurement units of a single measurement assembly together define a measurement plane, each of the planar elements of a single measurement assembly being arranged parallel to said measurement plane.

A lithographic apparatus, comprising:

• an illumination system for providing a beam of radiation;
• a support structure for supporting a patterning device that imparts said beam radiation with a pattern in its cross-section;
• a substrate holder for holding a substrate having a target portion;
• a projection system for projecting said patterned beam onto said target portion of said substrate;
• a moveable object that is moveable relative to a base, said moveable object comprising a grating that is integrated with said movable object;
• and
• a measurement system comprising an encoder head for measuring displacement of the moveable object relative to the base along a first translational direction of measurement in cooperation with the grating of the moveable object,

A device manufacturing method comprising:

• providing a substrate having a target portion;
• providing a beam of radiation;
• imparting said beam of radiation with a desired pattern in its cross-section;
• projecting the patterned beam of radiation onto the target portion of the substrate,
• measuring the displacement of a moveable object relative to a base along at least a first direction of measurement, said movable object having at least one reference part that is moveable in a plane of movement relative to said base in which the actual movement of said reference part is limited to within an area bounded by a closed contour;
• measuring displacement of the moveable object relative to a base along at least a first direction of measurement by employing a measurement system,
• wherein said measurement system comprises a sensor head and a planar element associated with said sensor head, the sensor head being mounted onto the base and the planar element being mounted onto the reference part of the moveable object or the planar element being mounted onto the base and the sensor head being mounted onto the reference part of the moveable object;
• wherein the planar element has a shape that is substantially similar to the shape of the closed contour.

A device manufacturing method comprising:

• providing a substrate having a target portion;
• providing a beam of radiation;
• imparting said beam of radiation with a desired pattern in its cross-section;
• projecting the patterned beam of radiation onto the target portion of the substrate,
• measuring displacement of the moveable object relative to the base along six degrees of freedom by employing a measurement system,
• wherein said measurement system comprises at least three primary measurement units for measuring translational displacement of the moveable object relative to the base in a first direction, at least two secondary measurement units for measuring translational displacement of the moveable object relative to the base in a second direction differing from the first direction, at least one tertiary measurement unit for measuring translational displacement of the moveable object relative to the base in a third direction differing from the first direction and from the second direction and extending at an angle relative to a directional plane, which directional plane is defined by a combination of the first direction and the second direction,
• wherein said measurement units are located at known relative positions,
• wherein each of said measurement unit comprises a sensor head and a planar element in which said sensor head is configured to transmit a beam to said planar element and said planar element is configured to reflect said beam to said sensor head in order to measure translational displacement of said sensor head relative to said planar element,
• wherein said measurement units are combined into at least three measurement assemblies, each of said three measurement assemblies comprising a primary measurement unit and at least one of a secondary measurement unit and a tertiary measurement unit, and
• wherein the directions associated with said measurement units of a single measurement assembly together define a measurement plane, each of the planar elements of a single measurement assembly being arranged parallel to said measurement plane.

A device manufacturing method, comprising:

• providing a substrate having a target portion;
• providing a beam of radiation;
• imparting said beam of radiation with a desired pattern in its cross-section;
• projecting the patterned beam of radiation onto the target portion of the substrate,
• providing a moveable object, which is moveable relative to a base, the moveable object comprising an integrated grating;
• and
• measuring displacement of the moveable object relative to the base in a first translational direction of measurement in cooperation with the grating of the moveable object by employing a measurement system,
• wherein said measurement system comprises an encoder head.