A control system and method are presented for use in optical measurements on patterned samples. The control system comprises a computer system configured for data communication with a measured data provider and comprising a data processor configured and operable to receive and process raw measured data of first and second types concurrently collected from the patterned sample being measured. said first and second types of the measured data comprising, respectively. scatterometry measured data. characterized by first relatively high signal-to-noise and predetermined first relatively low spatial resolution, and interferometric measured data characterized by second relatively low signal-to-noise and predetermined second relatively high spatial resolution, said data processor being configured to process the measured data to determine pattern parameters along said patterned sample characterized by said first signal to-noise and said second spatial resolution.

A system for measuring a beam. The system includes a measurement device configured to measure the beam and determine a signal based on the measured beam, and a fluid supply device configured to provide fluid as a fluid stream to, or surrounding, the beam. The system is configured to calculate noise of the signal, and to adjust a parameter of the fluid of the fluid stream to reduce the calculated noise.

A multi-column metrology tool may include two or more measurement columns distributed along a column direction, where the two or more measurement columns simultaneously probe two or more measurement regions on a sample including metrology targets. A measurement column may include an illumination sub-system to direct illumination to the sample, a collection sub-system including a collection lens to collect measurement signals from the sample and direct it to one or more detectors, and a column-positioning sub-system to adjust a position of the collection lens. A measurement region of a measurement column may be defined by a field of view of the collection lens and a range of the positioning system in the lateral plane. The tool may further include a sample-positioning sub-system to scan the sample along a scan path different than the column direction to position metrology targets within the measurement regions of the measurement columns for measurements.

A metrology and control system (100, 400, 500) for a laser beam in an EUV radiation source is disclosed. The system comprises an optical pickup (405, 540, 550) configured to measure a forward beam (410, 510, 520, 530) directed towards a target location (420, 535) and a return beam (415) reflected from the target location. The system also comprises actuatable optical devices (425, 430, 435, 465, 475, 555, 560, 565) configurable to direct and focus the forward beam onto the target location and align a measurement plane of the optical pickup with the target location. The actuatable optical devices are disposed before and after the optical pickup in a path of the forward beam, and the actuatable optical devices are controlled in response to a measurement of the forward beam and the return beam by the optical pickup.

In a method of measuring an alignment error, light is incident on a surface of a reference wafer having a known polarization transmittance at the surface. An image signal is obtained from the reference wafer at a set of angles including a first combination of values of a polarizer angle and an analyzer angle. Polarization transmittance of optical equipment including a polarizer and an analyzer is calculated from the image signal of the reference wafer. Light is incident on a surface of a measurement target wafer having a structure on the surface thereof. An image signal is obtained from the measurement wafer at a set of angles including a second combination of values of the polarizer angle and the analyzer angle. At least a portion of Mueller matrix is generated from the image signal of the measurement wafer.