Lambda Physik Ag

J&uuml;rgen Kleinschmidt

Peter Heist

Frank Voss

Andreas G&ouml;rtler

Uwe Stamm

Klaus Wolfgang Vogler

Peter Lokai

Wolfgang Zschocke

Uwe Leinhos

A wavelength calibration system determines an absolute wavelength of a narrowed spectral emission band of an excimer or molecular laser system. The system includes a module including an element which optically interacts with a component of an output beam of the laser within the tunable range of the laser system around the narrowed band. An inter-level resonance is detected by monitoring changes in voltage within the module, or photo-absorption is detected by photodetecting equipment. The absolute wavelength of the narrowed band is precisely determinable when the optical transitions occur and are detected. When the system specifically includes an ArF-excimer laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 193 nm and the element is preferably a gas or vapor selected from the group consisting of arsenic, carbon, oxygen, iron, gaseous hydrocarbons, halogenized hydrocarbons, carbon-contaminated inert gases, germanium and platinum vapor. When the system specifically includes F -laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 157 nm and the element is preferably a gas or vapor selected from the group consisting of selenium, bromine and silicon. The module is alternatively a purge chamber configurable for purging with a photo-absorbing gas.

Method and apparatus for wavelength calibration

An F -excimer laser has multiple closely-spaced spectral lines of interest around 157 nm, and one of the lines is selected by wavelength selection optics. The wavelength selection optics of a first preferred embodiment include a birefringent Brewster window enclosing the laser gas volume of the discharge chamber. The window preferably comprises MgF and is located at one end of the discharge chamber. One line is selected of the two when the optical thickness of the window is selected in coordination with rotatably adjustable, orthogonal refractive indices of the window. The transmissivity of the window is dependent on the orthogonal refractive indices and the optical thickness of the window. The wavelength selection optics of a second preferred embodiment include are at least partially within the laser active volume. In this way, line selection is performed in a manner which optimizes the combination of optical and discharge efficiency, resonator size and cost. The wavelength selection unit preferably includes a prism having a front surface oriented at Brewster's angle and a back surface oriented to receive and reflect an ordinary refracted ray travelling within the prism at a right angle to the back surface. The back surface also preferably includes a highly reflective coating to serve as the highly reflective surface of the resonator. The wavelength selection unit preferably further comprises an adjustment component for adjusting the orientation of the prism and for enclosing the other end of the housing, opposite the outcoupling end.

F2-laser with line selection

A line-narrowed excimer or molecular fluorine laser system includes a gain medium surrounded by a resonator for generating a laser beam, a discharge circuit including a plurality of electrodes for energizing the gain medium and a line-narrowing unit within the resonator for narrowing the bandwidth of the laser system. The resonator includes a deformable resonator reflector. A technique for adjusting the bandwidth of the laser system includes adjusting a surface contour of the deformable resonator reflector. A desired bandwidth may be selected manually or using a processor which automatically controls the surface contour adjustment.

Narrow band excimer or molecular fluorine laser with adjustable bandwidth

A line-narrowed excimer or molecular fluorine laser system includes a gain medium surrounded by a resonator for generating a laser beam, a discharge circuit including a plurality of electrodes for energizing the gain medium and a line narrowing unit within the resonator for narrowing the bandwidth of the laser system. The resonator includes a deformable resonator reflector. A technique for adjusting the bandwidth of the laser system includes adjusting a surface contour of the deformable resonator reflector. A desired bandwidth may be selected manually or using a processor which automatically controls the surface contour adjustment.

Excimer laser

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

A wavelength calibration system determines an absolute wavelength of a narrowed spectral emission band of an excimer or molecular laser system. The system includes a module including an element which optically interacts with a component of an output beam of the laser within the tunable range of the laser system around the narrowed band. An inter-level resonance is detected by monitoring changes in voltage within the module, or photo-absorption is detected by photodetecting equipment. The absolute wavelength of the narrowed band is precisely determinable when the optical transitions occur and are detected. When the system specifically includes an ArF-excimer laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 193 nm and the element is preferably a gas or vapor selected from the group consisting of arsenic, carbon, oxygen, iron, gaseous hydrocarbons, halogenized hydrocarbons, carbon-contaminated inert gases, germanium and platinum vapor. When the system specifically includes F,-laser chamber, the module is preferably a galvatron containing an element that photo-absorbs around 157 nm and the element is preferably a gas or vapor selected from the group consisting of selenium, bromine and silicon. The module is alternatively a purge chamber configurable for purging with a photo-absorbing gas.

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

Weissenfels, Germany

Jürgen Kleinschmidt

Growing community of inventors

Weissenfels, Germany

J&uuml;rgen Kleinschmidt

Jürgen Kleinschmidt