Abstract: A method according to one embodiment of the invention includes determining a map of a second part of a substrate belonging to a group of substrates. The method includes measuring a first part of at least one substrate belonging to the group to create an average profile map or average height map and computing a map of the second part of the substrate belonging to the group, based on the average profile map or the average height map. The computed map is stored for use during a later determination of a height or tilt of a substrate from the group.

Abstract: The present invention discloses a lithographic apparatus a lithographic apparatus with an improved focus control system. The lithographic apparatus includes an illumination system configured to provide a beam of radiation, a first support structure configured to support a patterning device that imparts the beam of radiation with a desired pattern in its cross-section, a second support structure that includes a substrate holder for holding a substrate, a projection system configured to project the patterned beam of radiation onto a target portion on a surface of the substrate, and a servo unit configured to position the substrate holder.

Abstract: In an off-axis levelling procedure a height map of the substrate is generated at a measurement station. The height map is referenced to a physical reference surface of the substrate table. The physical reference surface may be a surface in which is inset a transmission image sensor. At the exposure station the height of the physical reference surface is measured and related to the focal plane of the projection lens. The height map can then be used to determine the optimum height and/or tilt of substrate table to position the exposure area on the substrate in best focus during exposure. The same principles can be applied to (reflective) masks.

Abstract: A method according to one embodiment of the invention includes determining a map of a first part of a substrate belonging to a group of substrates. The method includes measuring a second part of at least one substrate belonging to the group, the second part being at least partially overlapping with the first part; computing a map (e.g. an average profile map or average height map) of the first part of the substrate belonging to the group, based on the second part; and storing the computed map, e.g. for use during a later determination of a height or tilt of a substrate from the group.

Abstract: In an off-axis levelling procedure a height map of the substrate is generated at a measurement station. The height map is referenced to a physical reference surface of the substrate table. The physical reference surface may be a surface in which is inset a transmission image sensor. At the exposure station the height of the physical reference surface is measured and related to the focal plane of the projection lens. The height map can then be used to determine the optimum height and/or tilt of substrate table to position the exposure area on the substrate in best focus during exposure. The same principles can be applied to (reflective) masks.