Abstract: A lithographic apparatus including a substrate table position measurement system and a projection system position measurement system to measure a position of the substrate table and the projection system, respectively. The substrate table position measurement system includes a substrate table reference element mounted on the substrate table and a first sensor head. The substrate table reference element extends in a measurement plane substantially parallel to the holding plane of a substrate on substrate table. The holding plane is arranged at one side of the measurement plane and the first sensor head is arranged at an opposite side of the measurement plane. The projection system position measurement system includes one or more projection system reference elements and a sensor assembly. The sensor head and the sensor assembly or the associated projection system measurement elements are mounted on a sensor frame.

Abstract: A lithographic apparatus includes an alignment sensor including a self-referencing interferometer for reading the position of an alignment target comprising a periodic structure. An illumination optical system for focusing radiation into a spot on said structure. An asymmetry detection optical system receives a share of positive and negative orders of radiation diffracted by the periodic structure, and forms first and second images of said spot on first and second detectors respectively, wherein said negative order radiation is used to form the first image and said positive order radiation is used to form the second image. A processor for processing together signals from said first and second detectors representing intensities of said positive and negative orders to produce a measurement of asymmetry in the periodic structure. The asymmetry measurement can be used to improve accuracy of the position read by the alignment sensor.

Abstract: A lithographic apparatus including a substrate table position measurement system and a projection system position measurement system to measure a position of the substrate table and the projection system, respectively. The substrate table position measurement system includes a substrate table reference element mounted on the substrate table and a first sensor head. The substrate table reference element extends in a measurement plane substantially parallel to the holding plane of a substrate on substrate table. The holding plane is arranged at one side of the measurement plane and the first sensor head is arranged at an opposite side of the measurement plane. The projection system position measurement system includes one or more projection system reference elements and a sensor assembly. The sensor head and the sensor assembly or the associated projection system measurement elements are mounted on a sensor frame.

Abstract: A lithographic apparatus including a substrate table position measurement system and a projection system position measurement system to measure a position of the substrate table and the projection system, respectively. The substrate table position measurement system includes a substrate table reference element mounted on the substrate table and a first sensor head. The substrate table reference element extends in a measurement plane substantially parallel to the holding plane of a substrate on substrate table. The holding plane is arranged at one side of the measurement plane and the first sensor head is arranged at an opposite side of the measurement plane. The projection system position measurement system includes one or more projection system reference elements and a sensor assembly. The sensor head and the sensor assembly or the associated projection system measurement elements are mounted on a sensor frame.

Abstract: A lithographic apparatus including a substrate table position measurement system and a projection system position measurement system to measure a position of the substrate table and the projection system, respectively. The substrate table position measurement system includes a substrate table reference element mounted on the substrate table and a first sensor head. The substrate table reference element extends in a measurement plane substantially parallel to the holding plane of a substrate on substrate table. The holding plane is arranged at one side of the measurement plane and the first sensor head is arranged at an opposite side of the measurement plane. The projection system position measurement system includes one or more projection system reference elements and a sensor assembly. The sensor head and the sensor assembly or the associated projection system measurement elements are mounted on a sensor frame.