Lifetime measurements on collector optics from Xe and Sn extreme ultraviolet sources

Abstract

Next generation lithography to fabricate smaller and faster chips will use extreme ultraviolet ͑EUV͒ light sources with emission at 13.5 nm. A challenging problem in the development of this technology is the lifetime of collector optics. Mirror surfaces are subjected to harsh debris fluxes of plasma in the form of ions, neutrals, and other radiation, which can damage the surface and degrade reflectivity. This manuscript presents the measurement of debris ion fluxes and energies in absolute units from Xe and Sn EUV sources using a spherical sector ion energy analyzer. Experimentally measured erosion on Xe exposed samples is in good agreement with predicted erosion. This result allows prediction of erosion using measured ion fluxes in experiment. Collector optic lifetime is then calculated for Xe and Sn sources without debris mitigation. Lifetime is predicted as 6 h for Xe EUV sources and 34 h for Sn EUV sources. This result allows calculation of expected collector optic lifetimes, which can be an important tool in optimizing source operation for high volume manufacturing.

Sculpting Nanometric Patterns: The Top‐down Approach

“…Recently, the EUV source power has been increased by more than an order of magnitude, raising productivity to more than two wafers per hour [53], but such improvements are still not enough. The Mo/Si mirror is directly exposed to the plasma and is therefore vulnerable to damage from the high-energy radiation [54] and other debris [50,55]. Also, during the high-energy exposure, carbon byproducts are produced and build up in the lenses system [41,56].…”

Debris transport analysis at the intermediate focus of an extreme ultraviolet light source

“…Such efforts seek to extend the lifetime of the collector optics and reduce the cost of ownership of a tool. 7,8 Typical techniques include the use of collimated foil traps, buffer gas, magnetic field confinement, secondary plasmas of low mass gas species to reduce the coulomb acceleration caused by the rapid expulsion of electrons from the plasma, as well as increasing chamber pressure to increase gas scattering in the short distance between the plasma and the optics. [9][10][11] While considerable research has been performed in preventing energetic ions and neutrals, as well as condensable Sn plasma fuel from reaching the reflective mirrors, mitigation techniques at the IF have not been widely investigated.…”

Time exposure performance of Mo-Au Gibbsian segregating alloys for extreme ultraviolet collector optics

“…An innovative idea using the Gibbsian segregation (GS) concept as the potential grazing incident EUV collector optics is developed and explored [10][11][12][13]. GS processes have been defined [14,15] as the tendency of certain solute elements in a homogenously interspersed solid solution to accumulate at imperfections, such as grain boundaries and interfaces in the bulk lattice that then may segregate to the free sur-faces.…”

“…If the regenerative transport processes (bulk, grain, interface diffusion) and surface renormalization are faster than the erosion time scale (i.e., the average time between large energy sputtering events), then the collector optics would be self-repairing. Early works have been published to assess the suitability of the GS alloy technology for early adoption of EUV lithography and test the validity with the theoretical estimate [10][11][12][13]. This work describes further experimental efforts to discover if GS alloys effectively ameliorate and self-heal the damage in grazing incidence EUV collector optics.…”