Research

The planned shift in the coming years in projection lithography EUV (wavelength of 13.5 nm emitter) will achieve resolution of 22 nm. We consider the technological capabilities to use EUV lithography for chip printing with resolution up to 16 nm, however, there are substantial risks that such progress will be impossible. This is primarily due to two main characteristics of the lithographic process – resolution and depth of focus. These two characteristics dictate the technical parameters of the whole system, particularly, optical parts of it. Resolution (R) is described by the formula R = k1 * λ / NA, where λ – the wavelength of the radiation used for printing, K1 – technical coefficient describing the characteristics of the optical system, NA – NA of the optical system. Another important characteristic of the depth of focus (DoF) is described as DoF = ë / (NA) 2. Currently being developed EUV lithographic apparatus with a resolution of R = 22 nm will have a mirror 11 with a numerical aperture NA = 0.25 at the value k1 = 0.4 and the corresponding value DoF = 200 nm. Transition to R = 16 nm would require an increase in the numerical aperture two times (which, in turn, significantly udorozhit optics used) and will lead to a dangerous decrease DoF technologically to a value of 50 – 100 nm.

Another possibility to improve resolution is to reduce the wavelength of the light used for the printing of circuits. Spectral intervals that can be used for lithography, determined primarily reflectivity of multilayer mirrors. “Islands” of high-reflection multilayer mirrors are scarce. Closest of these to 11.4 nm region associated with the use of mirrors containing beryllium and therefore are not considered. Other spectral range associated with the use of mirrors La / B4C and C / B4C, which are expected to have a very high reflectance in the spectral range of 6.6 – 6.7 nm.

Analysis shows that the use of shorter-wavelength radiation, particularly radiation at a wavelength of 6.6 – 6.7 nm, can significantly improve the resolution while maintaining important DoF and significantly reduce the required numerical aperture of the optical system. Achieving R = 16 nm may decrease, provided the numerical aperture of more than two times and decrease the number of mirrors used (used in the model calculations 11 and 7), which can significantly reduce the cost of the optical system.

Development of methods for the protection and cleaning of EUV multilayer optics in lithography machine

The planned shift in the coming years in projection lithography EUV (wavelength of 13.5 nm emitter) will achieve resolution of 22 nm. We consider the technological capabilities to use EUV lithography for chip printing with resolution up to 16 nm. However, serious risks in EUV lithography associated with fast enough pollution reflective multilayer mirrors in intense EUV radiation. The fact that even under ultrahigh vacuum (~ 10-8 Top) and so-called “clean room” on the surface of the mirrors always some amount of adsorbed water molecules and hydrocarbon. Interaction hard EUV photons and photoelectrons secondary adsorbed molecules leads to virtually complete dissociation of the adsorbed molecules and the formation of reactive radicals and atoms on the surface of the mirror.

As a result of this interaction, the oxidation of the top protective layer of the mirror, as well as the growth of the carbon film

The oxide layer and a layer of thick carbon just a few nanometers has lead to a significant loss of reflectivity of the EUV mirrors. Given the presence of up to a dozen mirrors in the optical system EUV lithography, this leads to a rapid blocking of the lithographic process.

International Programme for the development of semiconductor devices up to 2020 to the introduction of EUVL with a resolution <22 nm stands out as one of the most critical tasks – the task of “Control and clean the dirt optics lifetime achievement more than 5 years (30 thousand hours).”

No special cleaning system degradation of EUV multilayer optics for EUV lithography will occur within a few days, and the desired service life of 5 years. It follows that the treatment system must be removed repeatedly and continuously formed in EUVL contamination, and completely without affecting the surface of the mirror, even at the atomic level. This requires an extremely high selectivity, accuracy, and speed cleaning. An adequate solution to this problem is possible only within the framework of the lithography machine using the properties and conditions of EUVL. Therefore necessary to conduct further research and research and development, aimed at studying the possible mechanisms of the superfine cleaning surface at the atomic level and the development of clean technologies as well as control systems of purity and quality of the surface with an accuracy of ~ 0.1-0.3 nm.

Furthermore dirt may arise from defects in the surface contamination by particles, especially nano-sized, that can not be removed by conventional methods of purification of the particles. Therefore, research is also needed mechanisms to clean the surface of the EUV optics nanoparticles.

Features traditional diagnostic methods of nano-objects and nanostructures limited by their low information content, complexity of procedures for the preparation of the sample, a great time of measurement, the high cost of equipment and others. This makes it relevant to the development of optical methods nanodiagnostics that possess the potential benefits such as high information content, including the possibility of characterization studied nano-objects, flexibility, the possibility of operational remote sensing, nondestructive object under study, the ability of the individual diagnostics of nano-objects, the ability to create simple devices for nanodiagnostics and others.

The purpose of the project – the development of new methods and technologies of operational optical diagnostics of nano-objects and nanostructures based on optical methods and the creation of new devices based on these methods.

There will be developed individual diagnostic techniques dielectric nanoparticles and molecular structures of Raman spectra and fluorescence. It is planned to develop two types of devices based on advanced techniques: 1) Spectrometer Laser Raman and fluorescence-based multi-frequency laser confocal microscope, spectrograph compensated astigmatism (image spectrograph) and liquid nitrogen-cooled CCD. 2) Laser Raman microscope and fluorescence-based multifrequency laser mnogopolosovyh filters and high sensitivity CCD.

It will be developed a technique of optical nanodiagnostics complex molecular structures of the spectra of chromophore molecules, introduced into the sample as spectral nanoprobes. It is supposed to increase the accuracy of determining the coordinates of the observed chromophore molecules in the lateral plane of the sample to 5 nm. On the basis of the developed methodology is planned to design a prototype of the device for optical nanodiagnostics organic glasses, polymers and molecular crystals.

Will the technology of optical diagnostics nanocracks crystals of images impurity chromophore molecules introduced in said crack. It is planned to develop a technology for the introduction of the chromophore molecule probes nanocrack by dissolving these molecules in bicarbonate of sulfur hexafluoride gas or translated in a supercritical fluid state.

The main source of profit in the performance of the project is for sale, including companies ASML and INTEL, developed technologies and instruments for optical nanodiagnostics.

Development based on unique technologies developed over the past few years, members of the proposed project and the existing “know-how”, protected by patents.

The results of the project will form the basis for the industrial production of devices of optical diagnostics of nano-objects and nanostructures. To this end, at the initial stage of the project is planned to produce prototypes of the above types of optical devices nanodiagnostics