US 6,586,757 B2 · Plasma focus light source with active and buffer gas control

Abstract

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 π 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.

Claims27

Dependent claims

A high energy photon source for producing an extreme ultraviolet light beam defining a beam path and a beam direction said source comprising:

A. a vacuum chamber,
B. at least two electrodes mounted coaxially within said vacuum chamber and defining an electrical discharge region and arranged to create high frequency plasma pinches at a pinch site upon electrical discharge,
C. a working gas comprising an active gas and a buffer gas, said buffer gas being a noble gas, and said active gas being chosen to provide light at least one spectral line,
D. a gas control system for supplying the buffer gas and the active gas to said vacuum chamber and exhausting gas from the vacuum chamber so as to maintain the active gas at a desired concentration in the discharge region and minimize the active gas in the beam path outside the discharge region,
E. a pulse power system comprising a charging capacitor and a magnetic compression circuit said magnetic compression circuit comprising a pulse transformer for providing electrical pulses and voltages high enough to create electrical discharge between said at least one pair of electrode,
F. a collector-director unit configured to collect EUV beams from said pinch site and direct them along a predetermined path, and
G. a debris collector mounted near said pinch site and comprising at least 20 narrow passageways defined by a plurality of walls aligned with EUV beams emanating from said pinch site and directed toward said collector-director;
wherein said debris collector is comprised of two parts, an upstream part and a downstream part and said gas control system comprises a gas exhaust part for exhausting vacuum chamber gas at a location between said upstream part and said downstream part.

5 more elements

A high energy photon source for producing an extreme ultraviolet light beam defining a beam path and a beam direction said source comprising:

A. a vacuum chamber,
B. at least two electrodes mounted coaxially within said vacuum chamber and defining an electrical discharge region and arranged to create high frequency plasma pinches at a pinch site upon electrical discharge,
C. a working gas comprising an active gas and a buffer gas, said buffer gas being a noble gas, and said active gas being chosen to provide light at least one spectral line,
D. a gas control system for supplying the buffer gas and the active gas to said vacuum chamber and exhausting gas from the vacuum chamber so as to maintain the active gas at a desired concentration in the discharge region and minimize the active gas in the beam path outside the discharge region,
H. a pulse power system comprising a charging capacitor and a magnetic compression circuit said magnetic compression circuit comprising a pulse transformer for providing electrical pulses and voltages high enough to create electrical discharge between said at least one pair of electrode,
I. a collector-director unit configured to collect EUV beams from said pinch site and direct them along a predetermined path, and
J. a debris collector mounted near said pinch site and comprising narrow passageways aligned with EUV beams emanating from said pinch site and directed toward said collector-director;
wherein one of said two electrodes is hollow said gas control system comprises an exhaust means for exhausting vacuum chamber gas through said hollow electrode;
wherein said beam path defines a beam axis and said active gas is introduced into said vacuum chamber through a nozzle located on said beam axis and directed toward said hollow electrode.

6 more elements

Dependencies are inferred from the claim text.

Plasma focus light source with active and buffer gas control

Life of this patent

Plasma focus light source with active and buffer gas control

Life of this patent

Abstract

Claims27