Lithography technology is the key production technology supporting the integrated circuit (IC) manufacturing. With the continuously improved chip integration and performance, and the decreasing chip feature size, the extreme ultraviolet (EUV) lithography has replaced the deep ultraviolet lithography and become the most potential lithography technology to realize large-scale industrialization and commercial production.

The exposure system of the EUV lithography tool is composed of the EUV light source, illumination system, reflective mask, projection objective system, and synchronous workpiece platform. In this system, the light beam emerges from the light source, is shaped and homogenized by the illumination system, and then irradiates to the mask. After being reflected by the mask, the light is incident on the projection objective system, and finally on the wafer. As for the source, there is mainly discharge plasma source (DPP) and laser plasma source (LPP), which can meet the industrial exposure requirements on such aspects as energy and band. In recent years, the LPP source has gradually become the first choice for EUV lithography systems due to its high power and good stability. The illumination system concentrates on and shapes the light beam emitted by the light source to form a curved lighting field with high uniformity on the mask. The illumination system needs to match the light source size and the beam divergence angle and form highly uniform light spots on the arc-shaped field of the given size. In addition, the matching conditions of the corresponding pupil of the projector should be met. The function of the projection objective system is to image the graphics on the mask onto the silicon chip. The object surface of the projection objective is the mask, and the image surface is the silicon chip. The numerical aperture (NA) of the image space is determined by the exposure line resolution, and the magnification of the objective lens is determined by the exposure line size and the size of the mask pattern size, which is a strict integer multiple reduction ratio. Additionally, as most optical materials have strong absorption in EUV bands, the exposure system of EUV lithography tools is required to be a fully reflective system.

To continue the life of Moore's Law, continuously shorten the technical node, and ensure a certain yield, the exposure system of EUV lithography tools requires high NA and extremely high imaging quality. However, with the increasing NA on the image space of the projection objective, the "shadow effect" caused by the mask will be particularly significant. To this end, we propose an anamorphic EUV projector. In recent years, the NA0.33 EUV lithography tool has been put into production, and the next-generation NA0.55 anamorphic exposure system is under development. Relevant research institutions at home and abroad have invested a great deal of manpower and material resources in this field, and thus it is necessary to summarize the relevant work.

We first introduce the exposure system development of EUV lithography tools. With the continuously advancing technical nodes of large-scale IC manufacturing technology, the structural performance of existing EUV lithography tools is not sound enough to support their further development. The next-generation anamorphic lithography technology is introduced and completely new optical design methods are needed. Then, the relevant design methods of the projection objective system, anamorphic projection objective system, and illumination system at home and abroad are introduced. Finally, the trend of EUV lithography exposure systems at home and abroad is discussed.

Exposure systems of EUV lithography have been widely applied in the latest technology node, but the research on large fields of view and high image quality systems is still insufficient. To develop EUV lithography in our country and pre-research on high NA anamorphic EUV lithography, it is necessary to engineer related EUV lithography tools, including the mirror film design, tolerance analysis of the projection system and illumination system, and the control device design of fly's eye array.

The high NA anamorphic projection objective system tends to have a large pupil aberration due to the demagnification differences between the scanning direction and the vertical scanning direction. However, the illumination system and the objective lens system are connected through the pupil. According to the reverse design scheme of the illumination system, the entrance pupil of the objective lens is the starting point of the illumination system design, and thus the pupil plays an important role in the illumination system design. Therefore, to better design the illumination system and objective system, it can be considered to realize the collaborative design of the anamorphic projection objective system and illumination system by controlling the pupil aberration of the projection objective system.