Height measurement apparatus, lithographic apparatus, height measurement method, and method of manufacturing height measurement apparatus

摘要

To measure the height of a substrate. A height measuring device comprises an array of differential pressure sensors, each differential pressure sensor comprising a reference outlet at a predetermined distance from a reference surface, and a measurement outlet, each differential pressure sensor further comprising: An inlet configured to provide pressurized gas to the reference outlet and the measurement outlet. The flexible membrane is arranged such that the reference side of the flexible membrane is in fluid communication with the reference outlet and the measuring side of the flexible membrane is in fluid communication with the measuring outlet. The flexible membrane is configured to move when a pressure change occurs at the measurement outlet, and the detector is configured to monitor the movement of the flexible membrane. [Selected figure] Figure 2