Atomic-scale chemical mechanical polishing: advances and challenges for the post-Moore era

As the semiconductor industry enters the era beyond Moore's Law, the drive for atomic-scale precision in surface planarization becomes more critical than ever. Recognizing this challenge, researchers from Tsinghua have reported a comprehensive review outlining the recent advances, inherent challenges, and future directions of atomic-scale chemical mechanical polishing (CMP). Their work synthesizes the interdisciplinary efforts necessary to transcend existing limitations in materials processing and manufacturing precision, paving the way toward the next frontier of semiconductor device fabrication.

This review provides systematic insights for the targeted design and process optimization of the next-generation atomic-scale CMP technology.

As the feature size of integrated circuits gradually approaches the physical limit, atomic-scale manufacturing has become the key path to continue the Moore's Law. CMP, as the core process for wafer planarization, its accuracy directly affects the performance and yield of devices. However, as device dimensions shrink toward atomic scales, the fundamental mechanisms governing CMP are pushed into uncharted territory, exposing significant scientific and technological hurdles. Traditional CMP processes are well understood at macro- and nano-scales, but their extension to atomic precision involves complex coupling effects among mechanical forces, chemical reactions, thermal fields, and interfacial interactions. Emerging materials with diverse properties further complicate this landscape, demanding innovative solutions for defect control, removal uniformity, and process stability.

Despite progress of this technology, current understanding of the microscopic interactions during atomic-scale CMP remains insufficient. The challenge lies in deciphering the coupled roles of chemical reactions, mechanical stresses, and temperature effects that collectively dictate material removal at atomic resolutions. Such a nuanced understanding is essential to optimize process parameters, suppress surface and interface defects, and achieve defect-free, ultra-precise planarization. A critical requirement for future device architectures such as 3D integrated circuits and heterogeneous systems.

In terms of material diversity, CMP needs to deal with heterogeneous material systems ranging from metals (Cu, Co, Ru) to dielectric layers (SiO₂, low-k materials), and even wide-bandgap semiconductors (SiC, GaN). The significant differences in their physical and chemical properties pose extremely high requirements for the selective removal of the polishing solution and defect control. In terms of defect control, surface and interface defects such as corrosion, scratches, and residual particles deteriorate exponentially with the reduction in size, directly affecting the reliability of the device. In terms of process indicators, different process stages (such as shallow trench isolation, metal interconnection) have highly differentiated requirements for indicators such as removal rate, selectivity, and uniformity. Therefore, collaborative optimization of process, consumables, and equipment is urgently needed.

Addressing these pressing issues, this review provides a systematic overview of recent advancements across four core dimensions: mechanisms, processes, consumables, and equipment. The authors highlight how insights into atomic-scale interaction mechanisms reveal the synergistic roles of chemical and mechanical effects, enabling controlled material removal at atomic layers. They discuss innovative process strategies that optimize polishing parameters to enhance uniformity and precision. The review also emphasizes progress in designing multi-component slurries and interfacial regulation materials that improve removal selectivity and defect suppression. In addition, the development of fully integrated, 12-inch CMP platforms and external field-assisted technologies marks significant strides in achieving higher accuracy and efficiency with atomic-level control. This review systematically summarizes the research progress of atomic-scale CMP in terms of mechanism, process, consumables and equipment, and looks forward to its development direction in integrated circuit manufacturing in the post-Moore era.

Looking toward the future, the review also identifies key areas for further research. These include deciphering multiphysics-coupled removal mechanisms to understand and manipulate atomic interactions more precisely, developing adaptive process schemes that balance removal rate with defect reduction, and designing advanced consumables and equipment to meet the stringent demands of atomic-scale fabrication. The authors recommend integrating theoretical modelling, experimental investigation, and real-time process control to propel atomic-scale CMP from laboratory research to industrial maturity.

This work has been recently published in Materials Futures, a prominent international journal in the field of interdisciplinary materials science research.

Reference: Lifei Zhang, Xinchun Lu. Atomic-Scale Chemical Mechanical Polishing: Advances and Challenges for the Post-Moore Era[J]. Materials Futures. DOI: 10.1088/2752-5724/ae1fa2