Lambda Physik Ag

Uwe Leinhos

Uwe Stamm

Wolfgang Zschocke

Hans-Stephan Albrecht

J&uuml;rgen Kleinschmidt

Klaus Mann

Bernd Sch&auml;fer

Thomas Schr&ouml;der

A laser is provided having a gain medium including a laser gas and a photoabsorbing species. The photoabsorbing species has at least one photoabsorption line within an output emission spectrum of the laser. When the laser is an ArF-excimer laser, the photoabsorbing species is preferably either atomic carbon or molecular oxygen, which are formed after carbon- or oxygen-containing molecules introduced into the gain medium with the laser gas interact within the gain medium. An absolute wavelength of a narrowed emission of the laser can be calibrated when a narrowed output emission of the laser is tuned through at least one photoabsorption line of the photo-absorbing species. Preferably, a processor communicates with a detector and a wavelength selection unit, as well as a power supply when output beam energy is held constant, to automatically perform the calibration. Also preferably, one of tetrafluorocarbon, trifluoromethane, difluoromethane, fluoromethane and methane molecules are selected as the carbon-containing molecules and/or one of carbon dioxide, carbon monoxide or oxygen are selected as the oxygen-containing molecules. When carbon is selected, a photoabsorption line of atomic carbon at 193.0905 nm is compared with the spectral position of the narrowed emission of the laser to determine the absolute wavelength. When oxygen is selected, a photoabsorption line of molecular oxygen at one or more of 193.114 nm, 193.292 nm or 193.493 nm is compared with the spectral position of the narrowed emission. The absolute wavelength is calibrated within an accuracy range of around &plusmn;0.1 pm.

Internal wavelength calibration for tunable ArF-excimer laser using atomic carbon and molecular oxygen absorption lines

An ultraviolet light detection system is provided wherein a dark current background growth rate with total accumulated exposure dose is avoided, and parameters of an ultraviolet radiation source such as an ArF-excimer laser may be monitored without rapid degradation of the signal by the superposition of the dark current background over a desired signal. The invention provides a detector including a light sensitive element having a frequency conversion coating on its surface. The coating is preferably directly on the light sensitive element, absorbing incident ultraviolet light and re-emitting visible light in a direction toward the light sensitive element. The coating minimizes a dark current background that would otherwise appear when incident ultraviolet light impinges directly upon the light sensitive element, and thereby extends a lifetime of the light sensitive element. The detector is useful for detesting a wide range of ultraviolet wavelengths, and is particularly useful in solving the dark current growth rate with total accumulated exposure dose problem associated with detecting incident radiation under 240 nm.

Detector with frequency converting coating

A method and apparatus are provided for temporally stretching and smoothing of the pulses of an output beam of excimer and lithography lasers. The method and apparatus are based upon providing an optical delay line or circuit having a plurality of optical reflectors and a plurality of beam recombiners or splitters so arranged as to divide the pulse into numerous portions which vary in their travel time through the circuit. As a result, the energy of the incident pulse is greatly stretched and smoothed.

Optical pulse stretching and smoothing for ArF and F2 lithography excimer lasers

An ultraviolet light detection system is provided wherein a dark current background growth rate with total accumulated exposure dose is avoided, and parameters of an ultraviolet radiation source such as an ArF-excimer laser may be monitored without rapid degradation of the signal by the superposition of the dark current background over a desired signal. The invention provides a detector including a light sensitive element having a frequency conversion coating on its surface. The coating is preferably directly on the light sensitive element, absorbing incident ultraviolet light and re-emitting visible light in a direction toward the light sensitive element. The coating minimizes a dark current background that would otherwise appear when incident ultraviolet light impinges directly upon the light sensitive element, and thereby extends a lifetime of the light sensitive element. The detector is useful for detecting a wide range of ultraviolet wavelengths, and is particularly useful in solving the dark current growth rate with total accumulated exposure dose problem associated with detecting incident radiation under 240 nm.

A laser is provided having a gain medium including a laser gas and a photoabsorbing species. The photoabsorbing species has at least one photoabsorption line within an output emission spectrum of the laser. When the laser is an ArF-excimer laser, the photoabsorbing species is preferably either atomic carbon or molecular oxygen, which are formed after carbon- or oxygen-containing molecules introduced into the gain medium with the laser gas interact within the gain medium. An absolute wavelength of a narrowed emission of the laser can be calibrated when a narrowed output emission of the laser is tuned through at least one photoabsorption line of the photoabsorbing species. Preferably, a processor communicates with a detector and a wavelength selection unit, as well as a power supply when output beam energy is held constant, to automatically perform the calibration. Also preferably, one of tetrafluorocarbon, trifluoromethane, difluoromethane, fluoromethane and methane molecules are selected as the carbon-containing molecules and/or one of carbon dioxide, carbon monoxide or oxygen are selected as the oxygen-containing molecules. When carbon is selected, a photoabsorption line of atomic carbon at 193.0905 nm is compared with the spectral position of the narrowed emission of the laser to determine the absolute wavelength. When oxygen is selected, a photoabsorption line of molecular oxygen at one or more of 193.114 nm, 193.292 nm or 193.493 nm is compared with the spectral position of the narrowed emission. The absolute wavelength is calibrated within an accuracy range of around &plusmn;0.1 pm.

Growing community of inventors

Göttingen, Germany

Uwe Leinhos