An EUV light source is disclosed that may include a laser source, eg CO2 laser, a plasma chamber, and a beam delivery system for passing a laser beam from the laser source into the plasma chamber Embodiments are disclosed which may include one or more of the following; a bypass line may be provided to establish fluid communication between the plasma chamber and the auxiliary chamber, a focusing optic, eg mirror, for focusing the laser beam to a focal spot in the plasma chamber, a steering optic for steering the laser beam focal spot in the plasma chamber, and an optical arrangement for adjusting focal power

Laser produced plasma euv light source

Systems and methods are disclosed for reducing the influence of plasma generated debris on internal components of an EUV light source. In one aspect, an EUV metrology monitor is provided which may have a heater to heat an internal multi-layer filtering mirror to a temperature sufficient to remove deposited debris from the mirror. In another aspect, a device is disclosed for removing plasma generated debris from an EUV light source collector mirror having a different debris deposition rate at different zones on the collector mirror. In a particular aspect, an EUV collector mirror system may comprise a source of hydrogen to combine with Li debris to create LiH on a collector surface; and a sputtering system to sputter LiH from the collector surface. In another aspect, an apparatus for etching debris from a surface of a EUV light source collector mirror with a controlled plasma etch rate is disclosed.

Systems and methods for reducing the influence of plasma-generated debris on the internal components of an EUV light source

An EUV light source and method of operating same is disclosed which may comprise: an EUV plasma production chamber comprising a chamber wall comprising an exit opening for the passage of produced EUV light focused to a focus point; a first EUV exit sleeve comprising a terminal end comprising an opening facing the exit opening; a first exit sleeve chamber housing the first exit sleeve and having an EUV light exit opening; a gas supply mechanism supplying gas under a pressure higher than the pressure within the plasma production chamber to the first exit sleeve chamber. The first exit sleeve may be tapered toward the terminal end opening, and may, e.g., be conical in shape comprising a narrowed end at the terminal end.

Euv light source

A debris removable system (20) for removing a plasma produced residue debris on a reflecting surface (360) of an EUV source (26), which includes a stimulating mechanism (72) for exciting and ionizing the atoms to clean the reflecting surface (360): a collecting mirror (370); a filter (150); and a debris shield (202).

Collector for euv light source

The dense plasma focus (DPF) is a Z-pinch that has been studied for 50 years. Within ten years of its discovery by Fillipov and Fillipova in Russia and Mather in the USA, this dense pinch was scaled up to 2-MA currents and neutron outputs of ~ 1012/pulse. More remarkable is the fact that most of the relevant physics and scaling laws were elucidated within this first decade. The subsequent period has seen this type of pinch used as a teaching tool, developed as a portable neutron source for security applications, as a soft X-ray source for lithography, and as an energetic ion source for nanofabrication applications. This review builds upon several prior reviews. From the plasma physics standpoint, DPF physics is examined in light of fast Z-pinches to examine the similarities. More cross-fertilization between the two communities is suggested as a means to improve both types of pinches. From the applications standpoint, the many uses of DPFs are summarized to demonstrate the versatility of these pinches. Their ease of assembly and relatively low voltage operation have allowed DPFs to be disseminated worldwide as fusion testbeds (unlike their fast Z-pinch counterparts). Smaller or less economically developed nations have made valuable contributions to our understanding of the physics, as evidenced by the rich lode of publications that have advanced the field.

The Dense Plasma Focus: A Versatile Dense Pinch for Diverse Applications

Measurements are made of high-energy electron trajectories in a plasma focus as functions of position, time, energy, and angle of emission. The spatial resolution of the X-ray emission shows that low-energy X-rays are emitted from the anode surface. It is also suggested that the highest energy X-rays originate from a small region on the axis. The so-called shadow technique shows that the electron beam is perpendicular to the anode surface. Polar diagrams of medium and high-energy X-rays agree with the bremsstrahlung emission from a relativistic electron beam, the current of which is several 100 A.

https://iopscience.iop.org/article/10.1088/0032-1028/20/2/001/pdf

Trajectories of high energy electrons in a plasma focus

A new type of high‐power pinch apparatus consisting of disk electrodes was developed and diagnostic measurements to study its mechanism of dense plasma production have been made. The collapse fronts of the current sheets are well organized and dense plasma foci are produced on the axis with radial stability in excess of 5 μsec. A plasma density greater than 1018 cm−3 is determined with Stark broadening and CO2 laser absorption. Essentially complete absorption of a high‐energy CO2 laser beam has been observed. A plasma temperature of approximately 1 keV is measured with differential transmission of soft x rays through thin foils. The advantages of this apparatus over the coaxial plasma focus are improvements in (1) plasma volume, (2) stability, (3) containment time, (4) access to additional heating by laser or electron beams, and (5) the possibility of scaling up to a multiple array for high‐power operation.

Production of dense plasmas in a hypocycloidal pinch apparatus

The fluence of neutrons from a plasma focus was measured by gamma spectrometry of an activated silver target. This method results in a significant increase in accuracy over the beta‐counting method. Multiple detectors were used in order to measure the anisotropy of the fluence of neutrons. The fluence was found to be concentrated in a cone with a half‐angle of 30 deg about the axis, and to drop off rapidly outside of this cone; the anisotropy was found to depend upon the total yield of neutrons. This dependence was strongest on the axis. Neither the axial concentration of the fluence of neutrons nor its dependence on the total yield of neutrons is explained by any of the currently proposed models. Some other explanations, including the possibility of an axially distributed source, are considered.

Anisotropy of the neutron fluence from a plasma focus.

The X-ray emission from focused plasmas was observed with an image converter camera in the streak and framing modes. Use of a very high gain image intensifier enabled weak hard X-ray emission (above 25 keV) to be recorded. The use of an admixture of higher atomic number into the deuterium was avoided, and the role of the vapor from the anode surface could be discerned. The recorded bremsstrahlung emission seemed to be from a metallic plasma of copper released from the anode surface by bombardment from an intense electron beam. The intensity of emission was determined by the density of copper and the density and energy of the electron beam. The main emission recorded occurred several 100 nsec after the focus was over, which implies that the electric fields driving the beam existed for this duration. It is suggested that the fields were created by annihilation of magnetic flux for a time much longer than the focus duration.

Space and time resolved emission of hard X-rays from a plasma focus

A new staged plasma-focus geometry combining two Mather-type plasma-focus guns was constructed, and the current-sheet dynamics were investigated. The production of simultaneous pairs of plasma foci was achieved. The intensities of X-ray and fusion-neutron emission were measured and found to agree with the scaling law for a plasma focus. Advantages of this new geometry include the possibility of using plasma-focus type pinches in multiple arrays at power levels beyond the validity regime of the current scaling law for a single gun.

https://iopscience.iop.org/article/10.1088/0032-1028/20/10/005/pdf

Ja H. Lee

Papers

Trajectories of high energy electrons in a plasma focus

Production of dense plasmas in a hypocycloidal pinch apparatus

Anisotropy of the neutron fluence from a plasma focus.

Space and time resolved emission of hard X-rays from a plasma focus

Investigation of a staged plasma-focus apparatus