Certain aspects relate to a method for improving a lithography configuration. In the lithography configuration, a source illuminates a mask to expose resist on a wafer. A processor determines a defect-based focus exposure window (FEW). The defect-based FEW is an area of depth of focus and exposure latitude for the lithography configuration with an acceptable level of defects on the wafer. The defect-based FEW is determined based on a predicted probability distribution for occurrence of defects on the wafer. A processor also determines a critical dimension (CD)-based FEW. The CD-based FEW is an area of depth of focus and exposure latitude for the lithography configuration with an acceptable level of CD variation on the wafer. It is determined based on predicted CDs on the wafer. The lithography configuration is modified based on increasing an area of overlap between the defect-based FEW and the CD-based FEW.

One of gamma ray lithography systems includes a gamma ray generator and a wafer stage. The gamma ray generator is configured to generate a substantially uniform gamma ray. The gamma ray generator includes a plurality of gamma ray sources and a rotational carrier. The rotational carrier is configured to hold the gamma ray sources and rotate along a rotational axis. The wafer stage is disposed below the gamma ray generator and configured to secure a wafer.

An extreme ultraviolet lithography method is disclosed. In an example, the EUVL method includes forming a resist layer on a substrate; performing a first exposure process to image a first pattern of a first sub-region of a first mask to the resist layer; performing a second exposure process to image a second pattern of a second sub-region of the first mask to the resist layer; and performing a third exposure process to image a third pattern of a first sub-region of a second mask to the resist layer. The second and third patterns are identical to the first pattern. The first, second and third exposure processes collectively form a latent image of the first pattern on the resist layer.

An extreme ultraviolet light generation system includes: a chamber; a target generation unit; a laser system configured to output a first pre-pulse laser beam, a second pre-pulse laser beam, and a main pulse laser beam so that fluence of the first pre-pulse laser beam is 1.5 J/cm.sup.2 to 16 J/cm.sup.2 inclusive at a position where a target is irradiated with the first pre-pulse laser beam; and a control unit configured to control the laser system so that a first delay time from a timing of irradiation of the target with the first pre-pulse laser beam to a timing of irradiation with the second pre-pulse laser beam and a second delay time from the timing of irradiation of the target with the second pre-pulse laser beam to a timing of irradiation with the main pulse laser beam have a following relation:

the first delay time<the second delay time.

A radiation sensor apparatus for determining a position and/or power of a radiation beam, the radiation sensor apparatus including a chamber to contain a gas, one or more sensors, and a processor. The chamber has a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber generally along an axis, and exit the chamber through the second opening. Each of the one or more sensors is arranged to receive and detect radiation emitted from a region of the chamber around the axis. The processor is operable to use the radiation detected by the one or more sensors to determine a position and/or power of the radiation beam.

A method including obtaining (i) measurements of a parameter of the feature, (ii) data related to a process variable of a patterning process, (iii) a functional behavior of the parameter defined as a function of the process variable based on the measurements of the parameter and the data related to the process variable, (iv) measurements of a failure rate of the feature, and (v) a probability density function of the process variable for a setting of the process variable, converting the probability density function of the process variable to a probability density function of the parameter based on a conversion function, where the conversion function is determined based on the function of the process variable, and determining a parameter limit of the parameter based on the probability density function of the parameter and the measurements of the failure rate.

An exposure apparatus and method. The exposure apparatus includes a control system, light source system, plurality of illumination systems and plurality of projection objective lenses. The light source system is configured to emit a plurality of first illumination beams incident on the illumination systems. Each illumination system includes a variable attenuator and branch energy detector. The branch energy detector is configured to detect an illuminance level of a second illumination beam generated in the corresponding illumination system and feed it back to the control system. The control system is configured to adjust the illuminance levels of the second illumination beams in the respective illumination systems by controlling the respective variable attenuators therein. The exposure apparatus and method have improved exposure performance and allow finer and faster energy adjustments, thus enabling precise control and higher exposure accuracy.

A radiation source arrangement including: a radiation source operable to generate source radiation including source energy pulses; and at least one non-linear energy-filter operable to filter the source radiation to obtain filtered radiation including filtered energy pulses. The at least one non-linear energy-filter is operable to mitigate variation in energy in the filtered radiation by reducing the energy level of the source energy pulses which have an energy level corresponding to one of both extremities of an energy distribution of the source energy pulses by a greater amount than the source energy pulses which have an energy level corresponding to a peak of the energy distribution.

A method of patterning lithographic substrates, the method including using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

An optical pulse for an extreme ultraviolet (EUV) light source may be formed by illuminating a semiconductor material of a modulation system with a first light beam having a first wavelength; applying a voltage to the semiconductor material for a time duration, the applied voltage being sufficient to modify an index of refraction of the semiconductor material such that a polarization state of a light beam having a second wavelength passing through the semiconductor material is modified to pass through at least one polarization-based optical element of the modulation system; and forming an optical pulse by passing a second light beam having the second wavelength through the semiconductor material during the time duration.