Nikon Corporation

Tsutomu Mizugaki

Shigeru Sakuma

Shuuichi Takano

Kazuo Kimura

Masaki Shiozawa

Hiroki Jinbo

Norio Komine

Seishi Fujiwara

A manufacturing method for a single crystal of calcium fluoride by which it is possible to obtain a single crystal of calcium fluoride with adequately small double refraction, which can be used in optical systems for photolithography, and in particular, a single crystal of calcium fluoride with a large diameter (&oslash;200 mm or larger) having superior optical properties, which can be used for photolithography with a wavelength of 250 nm or less. A manufacturing method for a single crystal of calcium fluoride, having its optical properties improved through an annealing process in which a single crystal of calcium fluoride is contained in a sealable container, and said container is sealed and vacuumed, followed by, a process of heating with a heater arranged external to said container so that the temperature inside said container is raised to a first temperature, which is lower than the melting point of said single crystal of calcium fluoride, a process by which the temperature inside said container is maintained at said first temperature for a designated period of time, and a process by which the temperature inside said container is lowered to room temperature, wherein, the maximum temperature of the annealing process is set to be a first temperature within the range of 1020 to 1150&deg; C. Also provided is a manufacturing method for a single crystal of calcium fluoride having its optical properties improved through an annealing process such that, its maximum temperature during the thermal process is set to a first temperature which is within the range of 1020 to 1150&deg; C., and which is maintained for a designated period of time, and its cooling speed for reaching a second temperature, which is in the range of (or around) 600 to 800&deg; C., from said first temperature is set to be 1.2&deg; C./hour or less, or its cooling speed for reaching a second temperature, which is in the range of (or around) 700 to 900&deg; C., from said first temperature is set to be 1.2&deg; C./hour or less.

Manufacturing method for calcium fluoride and calcium fluoride for photolithography

A manufacturing method for a single crystal of calcium fluoride by which it is possible to obtain a single crystal of calcium fluoride with adequately small double refraction, which can be used in optical systems for photolithography, and in particular, a single crystal of calcium fluoride with a large diameter (&oslash; 200 mm or larger) having superior optical properties, which can be used for photolithography with a wavelength of 250 nm or less. A manufacturing method for a single crystal of calcium fluoride, having its optical properties improved through an annealing process in which a single crystal of calcium fluoride is contained in a sealable container, and said container is sealed and vacuumed, followed by, a process of heating with a heater arranged external to said container so that the temperature inside said container is raised to a first temperature, which is lower than the melting point of said single crystal of calcium fluoride, a process by which the temperature inside said container is maintained at said first temperature for a designated period of time, and a process by which the temperature inside said container is lowered to room temperature, wherein, the maximum temperature of the annealing process is set to be a first temperature within the range of 1020 to 1150&deg; C. Also provided is a manufacturing method for a single crystal of calcium fluoride having its optical properties improved through an annealing process such that, its maximum temperature during the thermal process is set to a first temperature which is within the range of 1020 to 1150&deg; C., and which is maintained for a designated period of time, and its cooling speed for reaching a second temperature, which is in the range of (or around) 600 to 800&deg; C., from said first temperature is set to be 1.2&deg; C./hour or less, or its cooling speed for reaching a second temperature, which is in the range of (or around) 700 to 900&deg; C., from said first temperature is set to be 1.2&deg; C./hour or less.

An annealing method for a single crystal of fluoride is provided. The method includes the steps of removing at least one of attached objects and absorbed objects from the surface of the single crystal of fluoride to clean the surface, thereafter annealing the single crystal of fluoride, including heating the single crystal of fluoride and gradually cooling the heated single crystal of fluoride, and removing a deteriorated layer which is formed on the surface of the single crystal of fluoride during the annealing step.

Method for annealing single crystal fluoride and method for

A manufacturing method for a single crystal of calcium fluoride includes the steps of degassing calcium fluoride powder particles to desorb impurities from surfaces of the calcium fluoride powder particles, preprocessing the degassed calcium fluoride powder particles by fusing the degassed calcium fluoride powder particles in a crucible to obtain a preprocessed product, and re-fusing the preprocessed product in a crucible to grow a single crystal of calcium fluoride.

Manufacturing method for calcium fluoride crystal and processing method

An optical member is provided for use in an image-focusing optical system for guiding light having a wavelength shorter than about 300 nm. The optical member includes a calcium fluoride crystal having a sodium concentration of less than about 0.2 ppm.

Image-focusing optical system for ultraviolet laser

A projection exposure apparatus capable of projecting and exposing mask pattern images onto a substrate by means of a optical projection system, the apparatus includes an optical illumination system capable of illuminating a mask utilizing an excimer laser illuminating light source in a wavelength range of 230 nm or less, and an optical projection system including optical members that include a calcium fluoride crystal with a total alkaline earth metal impurity content of 1.times.10.sup.18 atom/cm.sup.3 or less, and which projects images of the mask pattern onto a substrate. The calcium fluoride crystal is manufactured by a method including the steps of adding a fluorinating agent to a powdered calcium fluoride forming a mixture, placing the mixture in a growing crucible inside a vacuum furnace, and evacuating the vacuum furnace. Once the vacuum furnace is evacuated, the temperature is elevated a first time inside the vacuum furnace to a temperature exceeding a melting point of the mixture and is maintained at a predetermined constant temperature inside the vacuum furnace until a polycrystalline material is formed. The polycrystalline material is then cooled and the temperature inside the vacuum furnace is elevated until the polycrystalline material is melted, wherein crystal growth of the polycrystalline material is promoted and a crystal ingot is formed.

Growing community of inventors

Matsudo, Japan

Tsutomu Mizugaki