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Measurement Techniques for Diagnosis and Control of EUV Plasmas
Technology intended to measure and control the electron density and temperature of EUV plasma in detail using lasers.
Content of research
EUV plasmas and soft X-ray plasmas can easily achieve high light intensity and are used for semiconductor lithography and material diagnostics. On the other hand, for optimization (wavelength selectivity and high efficiency), control of the electronic state (electron density and electron temperature) of the plasma is necessary, but measurement of the electronic state has not been achieved yet with conventional techniques, and the electronic state had been unknown. The feature of this technology is that it enables detailed measurement of electron density and temperature in EUV plasmas by laser scattering measurement (Thomson scattering method) using a unique spectroscopic system. This makes it possible to develop light sources based on an understanding of the electronic state, which is the root of the mechanism by which plasma emits light.
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Development of a system to measure the plasma structure of an EUV light source, which has enabled us to explain the EUV light output from the electronic state of the plasma for the first time. Discovery of the hollow-like density structure.
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The system principle for measuring the plasma structure of an EUV light source. It is a scattering measurement using light (laser).
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The light output from the EUV light source can be explained by going back to the electronic state, which is the source of the emission of light.
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Although the electronic state is the basis of plasma applications, it is difficult to measure, which has been an obstacle to an understanding of the phenomena by going back to the electronic state and improvements could not be made. In addition to EUV light sources, we are developing research on various plasma applications based on electron measurements.
Potential for social implementation
- As a guideline for the development of EUV light source plasma, real-time observation of electronic states in the field is possible. Since EUV light intensity and electronic state are directly linked in the development of EUV lithography and EUV inspection light sources, this measurement is expected to shorten the development process for light source optimization.
Appealing points to industry and local governments
It is known that the amount of EUV light intensity from the EUV light source plasma is determined by the electronic state of the plasma. However, at present, the electronic state is not a target for measurement. By adding the electronic state to the measurement parameters in the development of the EUV light source, it will be possible to develop an original light source.