Abstract: A lithographic apparatus includes an illuminator for receiving a beam of EUV radiation from a radiation source apparatus and for conditioning the beam to illuminate a target area of a patterning device, such as a reticle. The reticle forms a patterned radiation beam. A projection system transfers the pattern from said patterning device to a substrate by EUV lithography. Sensors are provided for detecting a residual asymmetry in the conditioned beam as the beam approaches the reticle, particularly in a non-scanning direction. A feedback control signal is generated to adjust a parameter of said radiation source in response to detected asymmetry. The feedback is based on a ratio of intensities measured by two sensors at opposite ends of an illumination slit, and adjusts the timing of laser pulses generating an EUV-emitting plasma.

Abstract: A lithographic apparatus including a uniformity correction system is disclosed. Fingers move into and out of intersection with a radiation beam to correct an intensity of the radiation beam. Actuating devices are coupled to the fingers. A width of a tip of each of the fingers is half that of a width of the actuating devices. Systems and methods compensate for uniformity drift. An illumination slit uniformity caused by system drift is measured. First positions of uniformity compensators are determined based on the uniformity. Uniformity compensators are moved to the first respective positions. A substrate is exposed.

Abstract: A lithographic apparatus includes an illuminator for receiving a beam of EUV radiation from a radiation source apparatus and for conditioning the beam to illuminate a target area of a patterning device, such as a reticle. The reticle forms a patterned radiation beam. A projection system transfers the pattern from said patterning device to a substrate by EUV lithography. Sensors are provided for detecting a residual asymmetry in the conditioned beam as the beam approaches the reticle, particularly in a non-scanning direction. A feedback control signal is generated to adjust a parameter of said radiation source in response to detected asymmetry. The feedback is based on a ratio of intensities measured by two sensors at opposite ends of an illumination slit, and adjusts the timing of laser pulses generating an EUV-emitting plasma.

Abstract: A lithographic apparatus including a uniformity correction system is disclosed. Fingers move into and out of intersection with a radiation beam to correct an intensity of the radiation beam. Actuating devices are coupled to the fingers. A width of a tip of each of the fingers is half that of a width of the actuating devices. Systems and methods compensate for uniformity drift. An illumination slit uniformity caused by system drift is measured. First positions of uniformity compensators are determined based on the uniformity. Uniformity compensators are moved to the first respective positions. A substrate is exposed.