EUV lithography : historical perspective and road ahead

Lithography, in the form of carved type printing, can be dated as far back as the 3rd century AD. Starting from the 19th century it played a major role as the basis for dissemination and preservation of knowledge in the form of printed books, maps, newspapers, etc. In the mid 20th century, with the invention of the micro- and nanoelectronics, it took on a new meaning and became the basis for the patterning solutions of the modern day semiconductor industry. New challenges for further scaling of semiconductor devices in the 21th century brought Extreme Ultraviolet Lithography (EUVL) under close scrutiny of both hightech companies and scientific institutes. This growing interest has developed new insights into the science and technology of EUV production and EUV related processes in the areas of plasma physics, optics, surface physics and chemistry as well as many others. In his lecture he will describe his continuing voyage to explore this exciting world where these areas come together and he will sketch the possible technological developments that are still ahead of us

The temporal evolution of electrons in EUV-induced plasmas

We studied the temporal evolution of the electron density in a low pressure pulsed plasma induced by high energy photons (92 eV) by means of microwave cavity resonance spectroscopy (MCRS). Although MCRS generates space averaged information about the electron density, we demonstrate here the possibility to obtain spatial information by combining different resonant modes. The results show that the plasma expands to the wall of the cavity on a time scale of tens of microseconds. The speed of this expansion depends on the gas pressure; the higher the gas pressure, the slower the expansion. This effect is explained by ambipolar diffusion, which is inversely proportional to the gas pressure

Ion energies in EUV induced plasma: Measuring methods

No abstract

Collective Thomson scattering experiments on a tin vapor discharge in the prepinch phase

Partially collective Thomson scattering measurements have been performed on a triggered vacuum arc in tin vapor, which is a candidate source of extreme ultraviolet light for application in semiconductor lithography. In this paper, results on the electron densities and temperatures are presented for the prepinch phase of the discharge. Electron densities and temperatures increase from 1*10/sup 23/ m/sup -3/ to 1*10/sup 24/ m/sup -3/ and from 5 eV to over 30 eV, respectively, in about 100 ns. The results are confirmed by Stark broadening dat

Characterization of a vacuum-arc discharge in tin vapor using time-resolved plasma imaging and extreme ultraviolet spectrometry

Discharge sources in tin vapor have recently been receiving increased attention as candidate extreme ultraviolet (EUV) light sources for application in semiconductor lithography, because of their favorable spectrum near 13.5 nm. In the ASML EUV laboratory, time-resolved pinhole imaging in the EUV and two-dimensional imaging in visible light have been applied for qualitative characterization of the evolution of a vacuum-arc tin vapor discharge. An EUV spectrometer has been used to find the dominant ionization stages of tin as a function of time during the plasma evolution of the discharge

Investigation of ion energy distribution functions in EUV-induced plasmas by ion mass spectrometry

The creation of plasma by direct photo ionization by extreme ultraviolet radiation (EUV, 13.5 nm) is a common phenomenon in extraterrestrial planetary nebulae. However, this process has been difficult to reproduce in a laboratory because of the scarceness of EUV radiation sources. With the development of next-generation lithography tools, using EUV radiation to create smaller features on computer chips, EUV induced plasmas are now created in the low pressure background gas in lithography tools. Industries have realized that these plasmas are of significant importance with respect to machine lifetime. EUV induced plasmas affect exposed surfaces due to impacting ions. In this research an ion mass spectrometer, capable of measuring mass resolved energy spectra, is used to investigate the ion fluxes and ion energy distribution functions (IEDF) of EUV-induced plasmas. A xenon pinch discharge produces EUV radiation, which is focused into a measuring vessel with a low pressure hydrogen environment. In this vessel photo ionization creates free electrons with energies up to 76 eV, which further ionize the background gas by electron impact ionization. Ions are sampled through a 50 μm orifice in the spectrometer’s front plate. The influence of pressure and EUV power on the IEDF of the EUV-induces plasma are investigated. The results show the fast transformation of H2+ to H3+ by collisions with the background gas as a decrease in H2+ / H3+-ratio with pressure and distance to the EUV beam

EUV lithography : historical perspective and road ahead

Lithography, in the form of carved type printing, can be dated as far back as the 3rd century AD. Starting from the 19th century it played a major role as the basis for dissemination and preservation of knowledge in the form of printed books, maps, newspapers, etc. In the mid 20th century, with the invention of the micro- and nanoelectronics, it took on a new meaning and became the basis for the patterning solutions of the modern day semiconductor industry. New challenges for further scaling of semiconductor devices in the 21th century brought Extreme Ultraviolet Lithography (EUVL) under close scrutiny of both hightech companies and scientific institutes. This growing interest has developed new insights into the science and technology of EUV production and EUV related processes in the areas of plasma physics, optics, surface physics and chemistry as well as many others. In his lecture he will describe his continuing voyage to explore this exciting world where these areas come together and he will sketch the possible technological developments that are still ahead of us