摘要:
A gas discharge laser capable of operating at pulse rates in the range of 4,000 Hz to 6,000 Hz at pulse energies in the range of 5 mJ to 10 mJ or greater. Important improvements over prior art designs include: (1) a laser chamber having a gas flow path with a gradually increasing cross section downstream of the discharge electrodes to permit recovery a large percentage of the pressure drop in the discharge region, (2) a squirrel cage type fan for producing gas velocities through the discharge region of more than 76 m/s and capable of continuous trouble-free operation for several months, (3) a heat exchanger system capable of removing in excess of 16 kw of heat energy from the laser gas (4) a pulse power system capable of providing precisely controlled electrical pulses to the electrodes needed to produce laser pulses at the desired pulse energies in the range of 5 mJ to 10 mJ or greater at pulse repetition rates in the range of 4,000 Hz to 6,000 Hz or greater and (5) a laser beam measurement and control system capable of measuring pulse energy wavelength and bandwidth on a pulse-to-pulse laser with feedback pulse-to-pulse control of pulse energy and wavelength.
摘要:
The present invention provides an excimer laser capable of producing a high quality pulsed laser beam at pulse rates of about 4,000 Hz at pulse energies of about 5 mJ or greater. A preferred embodiment is an ArF excimer laser specifically designed as a light source for integrated circuit lithography. An improved wavemeter with special software monitors output beam parameters and controls a very fast PZT driven tuning mirror and the pulse power charging voltage to maintain wavelength and pulse energy within desired limits. In a preferred embodiment two fan motors drive a single tangential fan which provides sufficient gas flow to clear discharge debris from the discharge region during the approximately 0.25 milliseconds between pulses.
摘要:
The present invention provides an excimer laser capable of producing a high quality pulsed laser beam at pulse rates of about 4,000 Hz at pulse energies of about 5 mJ or greater. A preferred embodiment is an ArF excimer laser specifically designed as a light source for integrated circuit lithography. An improved wavemeter with special software monitors output beam parameters and controls a very fast PZT driven tuning mirror and the pulse power charging voltage to maintain wavelength and pulse energy within desired limits. In a preferred embodiment two fan motors drive a single tangential fan which provides sufficient gas flow to clear discharge debris from the discharge region during the approximately 0.25 milliseconds between pulses.
摘要:
An excimer laser with a purged beam path capable of producing a high quality pulsed laser beam at pulse rates in excess of 2,000 Hz at pulse energies of about 5 mJ or greater. The entire purged beam path through the laser system is sealed to minimize contamination of the beam path. A preferred embodiment comprises a thermally decoupled LNP aperture element to minimize thermal distortions in the LNP. This preferred embodiment is an ArF excimer laser specifically designed as a light source for integrated circuit lithography. An improved wavemeter is provided with a special purge of a compartment exposed to the output laser beam.
摘要:
The present invention provides a reliable modular production quality excimer laser capable of producing 10 mJ laser pulses in the range of 1000 Hz to 2000 Hz or greater. Replaceable modules include a laser chamber; a pulse power system comprised of three modules; an optical resonator comprised of a line narrowing module and an output coupler module; a wavemeter module, an electrical control module, a cooling water module and a gas control module. Important improvements have been provided in the pulse power unit to produce faster rise time and improved pulse energy control. These improvements include an increased capacity high voltage power supply with a voltage bleed-down circuit for precise voltage trimming, an improved commutation module that generates a high voltage pulse from the capacitors charged by the high voltage power supply and amplifies the pulse voltage 23 times with a very fast voltage transformer having a secondary winding consisting of a single four-segment stainless steel rod. A novel design for the compression head saturable inductor greatly reduces the quantity of transformer oil required and virtually eliminates the possibility of oil leakage which in the past has posed a hazard.
摘要:
The present invention provides a reliable modular production quality excimer laser capable of producing 10 mJ laser pulses in the range of 1000 Hz to 2000 Hz or greater. Replaceable modules include a laser chamber; a pulse power system comprised of three modules; an optical resonator comprised of a line narrowing module and an output coupler module; a wavemeter module, an electrical control module, a cooling water module and a gas control module. Important improvements have been provided in the pulse power unit to produce faster rise time and improved pulse energy control. These improvements include an increased capacity high voltage power supply with a voltage bleed-down circuit for precise voltage trimming, an improved communication module that generates a high voltage pulse from the capacitors charged by the high voltage power supply and amplifies the pulse voltage 23 times with a very fast voltage transformer having a secondary winding consisting of a single four-segment stainless steel rod. A novel design for the compression head saturable inductor greatly reduces the quantity of transformer oil required and virtually eliminates the possibility of oil leakage which in the past has posed a hazard.
摘要:
A high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. The chamber contains a working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at repetition rates of 1000 Hz or greater and at voltages high enough to create electrical discharges between the electrodes to produce very high temperature, high density plasma pinches in the working gas providing radiation at the spectral line of the source or active gas. A fourth generation unit is described which produces 20 mJ, 13.5 nm pulses into 2 &pgr; steradians at repetition rates of 2000 Hz with xenon as the active gas. This unit includes a pulse power system having a resonant charger charging a charging capacitor bank, and a magnetic compression circuit comprising a pulse transformer for generating the high voltage electrical pulses at repetition rates of 2000 Hz or greater. Gas flows in the vacuum chamber are controlled to assure desired concentration of active gas in the discharge region and to minimize active gas concentration in the beam path downstream of the pinch region. In a preferred embodiment, active gas is injected downstream of the pinch region and exhausted axially through the center of the anode. In another preferred embodiment a laser beam generates metal vapor at a location close to but downstream of the pinch region and the vapor is exhausted axially through the anode.
摘要:
A high energy photon source. A pair of plasma pinch electrodes are located in a vacuum chamber. The chamber contains a working gas which includes a noble buffer gas and an active gas chosen to provide a desired spectral line. A pulse power source provides electrical pulses at repetition rates of 1000 Hz or greater and at voltages high enough to create electrical discharges between the electrodes to produce very high temperature, high density plasma pinches in the working gas providing radiation at the spectral line of the source or active gas. A fourth generation unit is described which produces 20 mJ, 13.5 nm pulses into 2 &pgr; steradians at repetition rates of 2000 Hz with xenon as the active gas. This unit includes a pulse power system having a resonant charger charging a charging capacitor bank, and a magnetic compression circuit comprising a pulse transformer for generating the high voltage electrical pulses at repetition rates of 2000 Hz or greater.
摘要:
An oscillator-amplifier gas discharge laser system and method is disclosed which may comprise a first laser unit which may comprise a first discharge region which may contain an excimer or molecular fluorine lasing gas medium; a first pair of electrodes defining the first discharge region containing the lasing gas medium, a line narrowing unit for narrowing a spectral bandwidth of output laser light pulse beam pulses produced in said first discharge region; a second laser unit which may comprise a second discharge chamber which may contain an excimer or molecular fluorine lasing gas medium; a second pair of electrodes defining the second discharge region containing the lasing gas medium; a pulse power system providing electrical pulses to the first pair of electrodes and to the second pair of electrodes producing gas discharges in the lasing gas medium between the respective first and second pair of electrodes, and laser parameter control mechanism modifying a selected parameter of a selected laser output light pulse beam pulse produced by said gas discharge laser system by controlling the timing of the occurrence of the gas discharge between the first pair of electrodes and the occurrence of the gas discharge between the second pair of electrodes.
摘要:
An injection seeded modular gas discharge laser system capable of producing high quality pulsed laser beams at pulse rates of about 4,000 Hz or greater and at pulse energies of about 5 mJ or greater. Two separate discharge chambers are provided, one of which is a part of a master oscillator producing a very narrow band seed beam which is amplified in the second discharge chamber. The chambers can be controlled separately permitting separate optimization of wavelength parameters in the master oscillator and optimization of pulse energy parameters in the amplifying chamber. A preferred embodiment in an ArF excimer laser system configured as a MOPA and specifically designed for use as a light source for integrated circuit lithography. In the preferred MOPA embodiment, each chamber comprises a single tangential fan providing sufficient gas flow to permit operation at pulse rates of 4000 Hz or greater by clearing debris from the discharge region in less time than the approximately 0.25 milliseconds between pulses. The master oscillator is equipped with a line narrowing package having a very fast tuning mirror capable of controlling centerline wavelength on a pulse-to-pulse basis at repetition rates of 4000 Hz or greater to a precision of less than 0.2 pm.