An exposure method includes acquiring first height information through detection of a height of an upper surface of a substrate subjected to exposure; acquiring first position information through detection of a relative position between the substrate and a first mask having a first pattern to be transferred on the substrate; converting the first height information to second position information; acquiring second height information through detection of a height of the upper surface of the substrate; acquiring third position information through detection of a relative position between the substrate and a second mask having a second pattern to be transferred on the substrate; converting the second height information to fourth position information; calculating differential position information, based on difference between the second position information and the fourth position information; and aligning the second mask and the substrate, based on the third position information and the differential position information.

A method for using an extreme ultraviolet radiation source is provided. The method includes assembling a first droplet generator onto a port of a vessel; ejecting a target droplet from the first droplet generator to a zone of excitation in front of a collector; emitting a laser toward the zone of excitation, such that the target droplet is heated by the laser to generate extreme ultraviolet (EUV) radiation; stopping the ejection of the target droplet; after stopping the ejection of the target droplet, disassembling the first droplet generator from the port of the vessel; after disassembling the first droplet generator from the port of the vessel, inserting a cleaning device into the vessel through the port; and cleaning the collector by using the cleaning device.

A lithographic apparatus including a projection system having an optical axis and configured to project a radiation beam. The apparatus includes a measurement unit arranged to measure the radiation beam projected by the projection system, the measurement unit having an opening through which the radiation beam passes in use, and a sensing surface extending transverse to the optical axis and arranged to measure the radiation beam passing through the opening. The apparatus is configured to move the sensing surface in a plane transverse to the optical axis between a plurality of measurement positions. The radiation beam defines a view in the plane, and the measurement unit is configured such that the sensing surface captures, in each measurement position, a portion of the view smaller than 100% of the view.

The invention provides a light generating method and system, the method including: generating first light, the first light being capable of forming a first area, a second area, and a third area, and intensity of the first light in the first area being higher than that in the second area and the third area, respectively; generating second light, the second light being capable of simultaneously irradiating the first area and the second area; generating third light, the third light being capable of simultaneously irradiating the first area and the third area; and controlling intensity of the second light and the third light, respectively. The light generating method and system provided by the invention can not only generate light having a super-resolution that may approach infinitesimal in theory but also employ light output by a laser as the only original light source, featuring extremely low costs and freedom from the diffraction limit of the light source, showing a great prospect of applications in the field of lithography.

A determination method includes causing the state in each of the plurality of pixels to correspond to a plurality of states of a plurality of bits of an Ising model, and setting an evaluation function for evaluating a degree of coincidence between the target image and the formed image as a function of the plurality of bits, and determining which one of the plurality of states is to be set for each of the plurality of pixels on the basis of states of the plurality of bits included in a result obtained by evaluating the evaluation function by an Ising machine.

An extreme ultraviolet light generating apparatus for generating extreme ultraviolet light in a chamber according to one aspect of the present disclosure includes a piezoelectric element provided in the chamber; a pressure sensor configured to detect pressure in the chamber; a gas introducing unit configured to introduce gas into the chamber; an exhaust unit configured to exhaust the gas from the chamber; and a control unit configured to control application of a voltage to the piezoelectric element. The control unit is configured to determine whether or not to apply a voltage to the piezoelectric element based on information on the pressure in the chamber obtained by the pressure sensor.

An extreme ultraviolet light generation apparatus may include a chamber; a droplet generator configured to sequentially supply a first droplet of target substance to a plasma generation region in the chamber; and a gas flow generation device having a gas outlet for causing gas to flow along a travel direction of the first droplet around at least a part of a trajectory of the first droplet. Here, the droplet generator includes a vibrating element configured to generate, by applying vibration to a nozzle through which the target substance is output, a plurality of second droplets each having smaller volume than the first droplet and to cause the second droplets to be combined to generate the first droplet, and the gas outlet is located downstream, on a trajectory direction of the first droplet, of a position where the second droplets are combined and the first droplet is generated.

An exposure apparatus includes an illumination optical system for illuminating an original including a periodic pattern, a projection optical system for forming an image of the original on a substrate, a controller configured to cause light from the illumination optical system to be obliquely incident on the original such that a light intensity distribution which is line-symmetric with respect to a line, passing through an origin of a pupil region of the projection optical system and orthogonal to a periodic direction of the periodic pattern, is formed in the pupil region by diffracted light beams including diffracted light of not lower than 2nd-order from the periodic pattern, and to control exposure of the substrate such that each point in a shot region of the substrate is exposed in not less than two focus states.

A gas laser apparatus includes a laser oscillator including a pair of discharge electrodes disposed to face each other and configured to generate light from laser gas upon application of voltage, and a laser-side resonator in which the light resonates; an amplifier including an amplification unit and an amplification-side resonator; a beam splitter configured to reflect a part of the light from the laser-side resonator; an optical sensor configured to detect the light reflected by the beam splitter; and a processor configured to control the voltage based on an output from the optical sensor. The amplification-side resonator includes a rear mirror and an output coupling mirror. The laser-side resonator includes a grating and an output coupling mirror. The processor maintains the voltage at a constant value equal to or larger than a threshold of the voltage when the voltage is to be smaller than the threshold.

A lithography method in semiconductor fabrication is provided. The method includes generating multiple groups of small drops of a target material through a number of nozzles in such a way that small drops in each of the groups are aggregated to an elongated droplet of the target material. The method also includes generating a laser pulse from a laser generator to convert the elongated droplets to plasma which generates an EUV radiation. The method further includes exposing a semiconductor wafer to the EUV radiation.