According to STDaily citing a recent report on the official website of Okinawa Institute of Science and Technology Graduate University (OIST) in Japan announced that, the university has designed an extreme ultraviolet (EUV) lithography technology that surpasses the standard boundary of semiconductor manufacturing.

Lithography equipment based on such a design can use a smaller EUV light source, consuming less than one-tenth the power of traditional EUV lithography equipment, which can reduce costs and significantly improve the reliability and lifespan of the equipment.

In traditional optical systems, such as camera, telescope, and conventional ultraviolet lithography technologies, optical elements like apertures and lenses are arranged symmetrically along a straight axis. This method is not suitable for EUV rays because their wavelengths are extremely short and most will be absorbed by materials.

Thus, EUV light is guided using crescent-shaped mirrors, but this leads to light deviation from the central axis, sacrificing important optical properties and reducing the overall performance of the system.

To tackle this issue, the new lithography technology achieves its optical properties by aligning two axisymmetric mirrors with tiny central holes in a straight line. Due to the high absorption rate of EUV, each mirror reflection weakens the energy by 40%.

In accordance with industry standards, only about 1% of the EUV light source energy reaches the wafer after passing through 10 mirrors, which requires a very high EUV light output.

In contrast, limiting the number of mirrors from the EUV light source to the wafer to a total of four allows more than 10% of the energy to penetrate the wafer, which can largely bring down power consumption.

The core projector of the new EUV lithography technology, consisting of two mirrors similar to an astronomical telescope, can transfer the light mask image onto the silicon wafer. The team claims this configuration is incredibly simple since traditional projectors require at least six mirrors.

This was achieved by rethinking the theory of optical aberration calibration, and its performance has been verified by optical simulation software, which means it can meet the production requirements of advanced semiconductors.

Besides, the team designed a new type of illumination optical method called “dual-line field” for this novel technology, which uses EUV light to illuminate a plane mirror light mask from the front without interfering with the light path.

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(Photo credit: OIST)