Lithographic apparatus with two-dimensional alignment measurement arrangement and two-dimensional alignment measurement method

A lithographic apparatus configured to receive a substrate having at least one mark that includes a plurality of structures arranged in rows and columns, the lithographic apparatus including an alignment arrangement comprising a light source, optics and a detector, the light source being arranged for producing a light beam, the optics being arranged for receiving the light beam and producing an alignment beam, and the detector being arranged to produce an alignment signal, the lithographic apparatus comprising:

• an illumination system configured to condition a radiation beam;
• a support structure that supports a patterning device, the patterning device being capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam;
• a pattern generating system configured to project the patterned radiation beam onto a target portion of a substrate;
• an alignment beam generator that includes the optics and produces an alignment beam having an alignment beam spot with a first alignment beam spot portion extending in a first direction and a second alignment beam spot portion extending in a second direction that is substantially perpendicular to the first direction;
• a projection system that directs the alignment beam onto the at least one mark on the substrate, the at least one mark having a plurality of structures arranged in rows and columns,;
• beam directing optics that receive alignment radiation back from the at least one mark and direct the alignment radiation to the detector;
• an actuator that is adapted to move the substrate relative to the alignment beam;
• and
• a processor that is coupled to the actuator and the detector, and arranged to:
• control the actuator such that, during use, the columns of structures of the at least one mark and the rows of structures of the at least one mark, respectively, receive the first alignment beam spot portion and the second alignment beam spot portion, respectively;
• receive the alignment signal from said the detector;
• and
• calculate a two-dimensional position of the at least one mark based on the alignment signal.

An alignment measurement method in a lithographic apparatus, comprising:

• producing an alignment beam with an alignment beam spot having a first alignment beam spot portion extending in a first direction and a second alignment beam spot portion extending in a second direction that is substantially perpendicular to said first direction;
• directing said alignment beam to at least one mark on an object, said at least one mark having a plurality of structures arranged in rows and columns;
• scanning said first alignment beam spot portion across said columns of structures of said at least one mark and scanning said second alignment beam spot portion across said rows of structures of said at least one mark;
• receiving alignment radiation back from said at least one mark;
• producing an alignment signal based on said alignment radiation;
• and
• calculating a two-dimensional position of said at least one mark based on said alignment signal.

A computer program product comprising data and instructions to be loaded by a processor of a lithographic apparatus, and arranged to allow said lithographic apparatus to perform the alignment measurement method comprising:

• producing an alignment beam with an alignment beam spot having a first alignment beam spot portion extending in a first direction and a second alignment beam spot portion extending in a second direction that is substantially perpendicular to said first direction;
• directing the alignment beam to at least one mark on an object, said at least one mark having a plurality of structures arranged in rows and columns;
• scanning the first alignment beam spot portion across said columns of structures of said at least one mark and scanning the second alignment beam spot portion across the rows of structures of the at least one mark;
• receiving alignment radiation back from the at least one mark;
• producing an alignment signal based on the alignment radiation;
• and
• calculating a two-dimensional position of the at least one mark based on the alignment signal.