A gas laser apparatus includes a chamber containing a laser gas, a pair of electrodes disposed within the chamber, a fan disposed within the chamber, a motor connected to a rotating shaft of the fan, and a rotating speed control unit configured to control a rotating speed of the fan based on a wear-out parameter of the pair of electrodes.

A line narrowing module includes an enclosure, a prism which is disposed in an internal space of the enclosure and through which light passes, a mounter which is disposed in the internal space and on which the prism is mounted, a fixing unit which is disposed in the internal space and fixes the prism to the mounter, and a light blocking member. The light blocking member is disposed in the internal space and blocks scattered light in the internal space, the scattered light produced from the light and traveling to the fixing unit.

A light beam measurement device includes: a polarization measurement unit including a first measurement beam splitter provided on an optical path of a laser beam and configured to measure a polarization state of the laser beam having been partially reflected by the first measurement beam splitter; a beam profile measurement unit including a second measurement beam splitter provided on the optical path of the laser beam and configured to measure a beam profile of the laser beam having been partially reflected by the second measurement beam splitter; and a laser beam-directional stability measurement unit configured to measure a stability in a traveling direction of the laser beam, while the first measurement beam splitter and the second measurement beam splitter are made of a material containing CaF.sub.2.

A light beam measurement device includes: a polarization measurement unit including a first measurement beam splitter provided on an optical path of a laser beam and configured to measure a polarization state of the laser beam having been partially reflected by the first measurement beam splitter; a beam profile measurement unit including a second measurement beam splitter provided on the optical path of the laser beam and configured to measure a beam profile of the laser beam having been partially reflected by the second measurement beam splitter; and a laser beam-directional stability measurement unit configured to measure a stability in a traveling direction of the laser beam, while the first measurement beam splitter and the second measurement beam splitter are made of a material containing CaF.sub.2.

The excimer laser apparatus may include a laser chamber configured to contain gas, a pair of electrodes provided in the laser chamber, a power source unit configured to supply a pulse voltage between the pair of electrodes, a gas supply unit configured to supply gas into the laser chamber, a gas exhaust unit configured to partially exhaust gas from within the laser chamber, and a gas control unit configured to control the gas supply unit and the gas exhaust unit, where a replacement ratio of gas to be replaced from within the laser chamber increases as deterioration of the pair of electrodes progresses, the deterioration being represented by a deterioration parameter of the pair of electrodes.

The excimer laser apparatus may include a laser chamber configured to contain gas, a pair of electrodes provided in the laser chamber, a power source unit configured to supply a pulse voltage between the pair of electrodes, a gas supply unit configured to supply gas into the laser chamber, a gas exhaust unit configured to partially exhaust gas from within the laser chamber, and a gas control unit configured to control the gas supply unit and the gas exhaust unit, where a replacement ratio of gas to be replaced from within the laser chamber increases as deterioration of the pair of electrodes progresses, the deterioration being represented by a deterioration parameter of the pair of electrodes.

An excimer laser chamber device may include: a the laser chamber; a first electrode provided in the laser chamber; a second electrode provided in the laser chamber to face the first electrode; an electrode holder provided in the laser chamber to be connected to a high voltage; at least one connecting terminal including a first anchored portion anchored to the first electrode and a second anchored portion anchored to the electrode holder, the at least one connecting terminal being configured to electrically connect the first electrode and the electrode holder; a guide member held by the electrode holder, the guide member being configured to position the first electrode in a direction substantially perpendicular to both a direction of electric discharge between the first electrode and the second electrode and a longitudinal direction of the first electrode; and an electrode-gap-varying unit configured to move the first electrode in a direction substantially parallel to the direction of electric discharge.

A high-voltage pulse generator may include a number “n” (n is a natural number of not less than 2) of primary electric circuits connected in parallel to one another on the primary side of a pulse transformer, and a secondary electric circuit of the pulse transformer, which is connected to a pair of discharge electrodes disposed in a laser chamber of a gas laser apparatus. The “n” primary electric circuits may include a number “n” of primary coils connected in parallel to one another, a number “n” of capacitors respectively connected in parallel to the “n” primary coils, and a number “n” of switches respectively connected in series to the “n” capacitors. The “n” primary electric circuits may be connected to a number “n” of chargers for charging the “n” capacitors, respectively. The secondary electric circuit may include a number “n” of secondary coils connected in series to one another, and a number “n” of diodes each connected to opposite ends of each of the “n” secondary coils, to prevent a reverse current flowing from the pair of discharge electrodes toward the secondary coils.

A method of manufacturing a semiconductor includes generating plasma in an amplifying tube using gas as a gain medium; detecting a state of the plasma generated in the amplifying tube; determining a virtual laser gain based on the detected state of the plasma; controlling the state of the plasma such that the virtual laser gain is within a target range; and manufacturing the semiconductor device including performing an exposure process on a substrate using a laser beam output from the amplifying tube adjusted to have the virtual laser gain within the target range.

There may be provided a laser unit including a display configured to display one or both of electric power consumed by the laser unit and electric energy consumed by the laser unit.