极紫外光刻胶的研究进展与展望

Research Progress and Prospects of Extreme Ultraviolet Photoresists

光刻胶是微电子领域微细图形加工的关键材料,具有技术含量高、生产工艺复杂、研发周期长等特点,已被广泛应用于平面显示、印刷电路板、集成电路、微机电系统等领域。特别是在集成电路产业,光刻胶材料的不断发展为摩尔定律的持续有效性提供了重要保障,而芯片制程工艺节点的持续推进又对光刻胶材料的分辨率提出了更高要求。作为目前最先进的芯片制造技术,极紫外(EUV)光刻的重要性日益凸显,与之配套的极紫外光刻胶也正受到越来越多的关注。为了更好地推动这一集成电路用关键材料的发展,对近年来国内外极紫外光刻胶的最新研究进展进行了总结与讨论。首先介绍了极紫外光刻胶的研究背景及其面临的挑战,接着从非金属基和金属基极紫外光刻材料两个方面进行了分类介绍,重点总结了化学放大、非化学放大、分子玻璃、氢倍半硅氧烷、金属有机小分子、金属氧化物等典型EUV光刻胶在近几年的研究进展,最后对当前广受学术界和产业界关注的金属氧簇型EUV光刻胶技术路线进行了全面总结与展望。

Significance Photoresist is a photosensitive material that exhibits changes in solubility upon exposure to light or radiation.Moreover,photoresist plays a key role in micro pattern processing in the field of microelectronics,which is characterized by high technological content,complex production processes,and long research and development cycles.Photoresist is widely used in flat displays,printed circuit boards,integrated circuits,microelectromechanical systems,and other fields.In the integrated circuit industry,the continuous development of photoresist materials provides an important guarantee for the continuation of Moore’s Law,and the continuous advancement of chip nodes puts higher requirements on the resolution of photoresist materials.Extreme ultraviolet(EUV)lithography is currently the most advanced chip manufacturing technology,and it is becoming increasingly prominent.Hence,the accompanying EUV photoresist is also receiving increased attention.Progress For an extreme ultraviolet light source,the photon corresponding to the wavelength of 13.5 nm for the radiation light has an energy of 92 eV,which is much higher than the ionization potential of the component atoms of the photoresist material.This leads to a significant difference in the reaction mechanism of extreme ultraviolet photoresist,compared with the previous generation of photoresists.Moreover,the glass transition temperature,thermal decomposition temperature,film-forming properties,extinction coefficient,refractive index,particle content,metal impurity content,and other parameters of the material also impact the performance of EUV photoresists.These factors make the development of extreme ultraviolet photoresists extremely challenging.To better promote the development of such key materials for integrated circuits,this study summarizes and discusses the latest domestic and international research progress on extreme ultraviolet photoresists.First,the research background and challenges faced by extreme ultraviolet photoresists are introduced.Then,a classification introduction is made from the perspectives of non-metallic and metal-based extreme ultraviolet photoresist materials.Four typical non-metallic EUV photoresists are presented:chemical amplification(Fig.1),non-chemical amplification(Fig.3),molecular glass(Fig.7),and hydrogen sesquioxan(Fig.9).Three metal-based EUV photoresists are presented:small metal-organic molecules(Fig.10),metal oxides(Fig.12),and metal oxo clusters(Fig.13).A comprehensive summary and outlook are provided for the current technological route of metal oxide cluster type EUV photoresists,which has received widespread attention from both academia and industry.Overall,traditional organic photoresists,as represented by chemically amplified photoresists,are widely used in deep ultraviolet(DUV)and previous lithography technologies,and they show potential in EUV lithography applications.However,their inherent weak EUV photon absorption gives them a natural disadvantage in terms of EUV sensitivity.Correspondingly,introducing metal elements with high EUV photon absorption cross-sections can significantly improve sensitivity and reduce the output power requirements of EUV lithography machines,which are already extremely technologically complex.In addition,metal based EUV photoresists can enhance the etching resistance under low film thickness and thin lines,which is conducive to pattern transfer in advanced manufacturing processes.Conclusions and Prospects With the continuous development of EUV lithography technology,higher requirements are being put forward for EUV photoresists.In this context,various non-metallic and metal-based EUV lithography materials are reviewed,focusing on the latest research progress domestically and abroad.The results of a comparison of the lithographic performances of typical non-metallic and metal-based EUV photoresists indicate that metal-based EUV photoresists,especially metal oxo clusters,may become the mainstream technology route for the next generation of high-performance EUV photoresists.Research in this field has made good progress in recent years.However,considering the rich diversity and huge amount of known metal oxo clusters,research into their applications in EUV lithography is relatively limited,and the mechanism of solubility changes caused by photolithography reactions is still unclear.Therefore,it is crucial to develop new metal oxo cluster lithography materials using molecular design strategies.To achieve this goal,it is necessary to understand the inherent relationship between photolithography performance and the structures of metal oxo clusters.Therefore,lithography function-oriented structural design and the precise fabrication of metal oxo clusters are expected to greatly promote the development of EUV photoresists.In this process,the effects of metal cluster nuclei,coordination bonds between metals and ligands,and peripheral ligand layers on the performance of EUV lithography should be considered comprehensively.