Stress Of Multilayer Film Research Articles

РАДИАЦИОННАЯ СТОЙКОСТЬ МНОГОСЛОЙНЫХ НАНОСТРУКТУРИРОВАННЫХ ПОКРЫТИЙ нк-ZrN/a-ZrCu, ОБЛУЧЕННЫХ ИОНАМИ ГЕЛИЯ

The paper presents the results of surface radiation erosion and stress evolution of multilayer coatings made of ZrN ceramic layers and metallic glass (Zr-Cu) under He2+ ion irradiation with an energy of 40 keV and fluences from 5·1016 to 1.1·1018 cm−2. Multilayer coatings of nc-ZrN/a-Zr1−хCuх with an elementary layer thickness of 5 nm/5 nm and 5 nm/10 nm are formed by reactive magnetron sputtering with different copper Cu contents (x = 0.45; 0.53; 0.61 and 0.74). Sputtering took place from Zr and Cu targets at a substrate temperature T = 300 °C. The surface of the films remained stable up to a fluence of 5·1017 cm−2. It has been found that with an increase in the ion fluence, the radiation erosion of the surface develops according to the flecking mechanism. It has been established that an increase in the thickness of the amorphous layer and the copper content increase the resistance to irradiation (the critical fluence increases from 5·1017 cm−2 to 8·1017 cm−2). Irradiation with helium He ions leads to a decrease in the level of compressive stresses. Reducing the level of stresses in multilayer films is associated with the effects of changes in the microstructure of the layers (shape distortion) at a dose of 2·1017 cm−2 and radiation erosion at a dose of 8·1017 cm−2.

Research on Optical and Mechanical Compatible Design Technology of Multilayer Films

The stress’s accumulation will critically affect optical device stability, leading to components’ deviation and film peeling. Stress control techniques based on strain cancelation cannot precisely match film stress, and it is difficult to reduce the total stress of multilayer film to ultra-low levels. Existing software for film system design is mainly based on 2D design concepts such as wavelength-spectrum and does not consider 3D design concepts such as wavelength-spectrum-stress, but the stress parameter plays an essential role in film performance, and it is necessary to use it as an optimization index for film design. In this paper, we introduce mechanical synchronization design into film system design. The multilayer film’s optimal structure is precisely matched by the genetic algorithm, and an ultra-low stress and wide-spectrum optical film element is developed under the dual requirements of optical performance and mechanical performance. This technique incorporates computer-aided design and automatically seeks an optimal combination of layered film nanostructures through self-compiled optical and mechanical compatible design software. While ensuring invariant optical properties, it can effectively reduce the total stress of multilayer film. This can provide a new idea for film stress control.

Stress, reflectance, and temporal stability of sputter-deposited Mo/Si and Mo/Be multilayer films for extreme ultraviolet lithography

Precisely figured optics coated with high-reflectance multilayer films are an integral part of an extreme ultraviolet (EUV) projection lithography system. Since multilayer film stress deforms these precisely figured optics, it is important that this stress be characterized and that suitable methods are developed to negate the effects of the stress. However, these techniques must reduce or compensate for the effects of film stress without significantly reducing the EUV reflectivity, since the reflectivity has a strong impact on the throughput of an EUV lithography system. Different techniques for reducing multilayer stress are examined. The technique of varying the base pressure (impurity level) yielded a 10{percent} decrease in stress with a 2{percent} decrease in reflectance for our multilayers. A study of annealing during Mo/Si deposition is performed; a stress reduction of 70{percent} is observed at 200{degree}C, similar to what has been found for postdeposition annealing. However, the reflectance loss was 3.9{percent} versus 1.3{percent} for postdeposition annealing, indicating that if annealing is performed on our films it should be done after multilayer deposition. A decrease of approximately 9{percent} in the bilayer period thickness was observed for annealing during deposition at temperatures near 120 to 140{degree}C, much larger than the thickness changes observed duringmore » postdeposition annealing. A new athermal buffer-layer technique is developed to compensate for the effects of stress. Using this technique with amorphous silicon and Mo/Be buffer layers it is possible to obtain Mo/Be and Mo/Si multilayer films with a near zero net film stress and less than a 1{percent} degradation in reflectivity. It is important that the multilayer coated optics are stable with time and that the stress reduction and compensation techniques do not degrade the stability. The temporal stability of 100-nm-thick Mo, Si, and Be single-layer films, Mo/Si and Mo/Be multilayer films, and films treated with various stress reduction/compensation techniques are investigated. Results are reported showing the reflectance peak wavelength to be stable to within 0.15{percent} for both the multilayers and the stress-compensated multilayers. Therefore, stability is maintained when these buffer-layer stress compensation techniques are applied. Mo/Si multilayer films exhibit a {approximately}10{percent} short-term decrease in the stress over the first few months after deposition, but the stress stabilizes thereafter. The Mo/Si reflectance is observed to be stable to within 0.4{percent} over a period of over 400 days. The Mo/Be multilayer film stress was stable to within about 2{percent} over 300 days, and the reflectance was observed to decrease by about 1.5{percent} over the same period. For Mo/Si on a Mo/Be buffer layer the stress changed from {minus}28 to +3 MPa, and the reflectance decreased by approximately 0.4{percent} for a period of over 300 days. For Mo/Be on an a-Si buffer layer, the stress changed from {minus}23 to {minus}3 MPa, and the reflectance decreased by {approximately}1.8{percent} for a period of over 300 days; this drop in reflectance is believed to be due primarily to the Mo/Be and not the addition of the buffer layer. {copyright} {ital 1999 Society of Photo-Optical Instrumentation Engineers.}« less

Internal stress in thin films prepared by ion beam and vapor deposition

Abstract The effect of ion beam irradiation on the internal stress in thin films prepared by ion beam and vapor deposition (IVD) was studied. The thin films were prepared by the evaporation of nickel or silicon metals and simultaneous irradiation on Si(100) substrates by argon ion beams. The energies of the argon ions were changed in the range 0.5–10.0 keV, while the transport ratio of vapor atoms to ions was changed from 5 to 15. The internal stresses in the thin films were measured by the displacements of the substrates after deposition, and the results show that the internal stress changed from compressive to tensile with increasing ion beam energy. In addition, the control of the internal stresses in multilayer films prepared by IVD was investigated. It was found that it is possible to control the internal stress in a multilayer film by a suitable combination of the layers.

Bulk and interface stresses in silver-nickel multilayered thin films

Stresses were measured in 〈111〉-textured Ag/Ni multilayered thin films from the substrate curvature and from lattice parameter measurements by x-ray diffraction. The difference between the total multilayer film stress and the layer deposition stresses can be attributed to a tensile interface stress of −2.27±0.67 J/m2. Interfacial phase formation is unlikely in this system as indicated by the exceptionally low mutual solubilities.

Methane adsorbed on graphite. IV. Multilayer growth at low temperature.

The structure of methane films on a smooth graphite substrate has been simulated along an isotherm (T=25 K) by use of canonical ensembles. The coverage was sequentially increased in small increments from 0.90 to 4.2 (\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 ) monolayers. Comparisons are made with simulations of argon adsorbates, recent laboratory experiments, and analytical calculations. The results indicate the first and second methane layers are not mutually commensurate for all but the highest coverage in this range, but, for the same conditions, argon layers are mutually commensurate. The incommensurate first and second layers modulate each other to form an interesting new structure where the unit cells in each of the layers have become oblique. The structural distribution functions suggest the compressive stresses in multilayer films are better described by a pressure tensor with radial and vertical components which are decreasing functions of the height above the substrate. Comparisons are made to results from Ar/graphite and ${\mathrm{CH}}_{4}$/Au(111) systems.