With state-of-the-art EUV lithography moving to the 3 and 2 nm nodes, yield control and connected to that particle contamination control are crucial aspect of High-Volume Manufacturing (HVM). While much progress has been made in recent years, the continuously tightening node requirements translate into ever more stringent requirements on particle contamination control. Besides for lithographic scanners, operating in a low background pressure hydrogen gas environment, particle contamination control is also important for space exploration (which also operates in low pressure environments), where particles may lead to malfunctioning moving parts, loss of solar power generation, and human health hazards. A key factor in release of particles in these low-pressure environments is the ionization of the low-pressure background gas by energetic photons (for instance EUV in lithographic scanners, and broadband energetic radiation in space), and resulting plasma with fast electrons of 25 eV and above. Experiments show that these electrons can mobilize and remove particles on most materials, and that the governing effects strongly depend on the substrate material, coating and surface finishing. This paper will discuss work on understanding and modeling these effects and describe possible solution paths to improve particle contamination control, both for lithographic scanners and for space exploration.
With the introduction of the NXE:3400 scanner, EUV has progressed to High-Volume Manufacturing (HVM) for sub-10nm lithography. In this context, manufacturers are pursuing a dual-path approach towards near-zero reticle defectivity: EUV-compatible pellicle or zero particles towards reticle by advanced particle contamination control. However, given the high cost of reticles, it is equally important to establish tooling and processes for cleaning the reticle should a particle land on it.
To this end, we investigated an extension of the existing MeRiT mask repair product line to also address particle defects. The resulting tool for particle removal leverages the MeRiT know-how on defect repair using e-beam based repair schemes with a novel in-situ manipulator to remove particles, including real-time observation by SEM (scanning electrode microscopy).
This paper will focus primarily on a feasibility study, successfully demonstrating proof of principle of defect removal, reviewing the area of interest by SEM and showing no collateral damage being observed by SEM-EDX (Energy Dispersive X-ray) analysis.
Extreme ultraviolet (EUV) lithography is a technology for high volume manufacturing (HVM) of integrated circuits. HVM defines critical specification for cleanliness of reticles (masks) used to impose a pattern on wafers. EUV-induced hydrogen plasma produced by photoionization of the H2 gas by the 13.5 nm photons plays an important role in the release and transport of particles from contaminated surfaces to the reticle. It was observed that the rate of particle deposition on the reticle in an EUV scanner scales with EUV power which in turn defines the properties of the EUV-induced plasma to increase the knowledge regarding this phenomenon. We demonstrate images, acquired by a scanning electron microscopy (SEM) to illustrate morphological changes, accumulating in particles of tin, lead and lead oxide that were subject to applied hydrogen plasma (non-EUV). These changes led to the potential loss of adhesion of these materials to the relevant surfaces or potential defectivity outbreaks via explosive fragmentation. This work proposes that the mechanical stress in particles' material lattice caused by accumulation of hydrogen bubbles under the surface plays the major role in the morphological changes observed.
With the introduction of the NXE:3400B scanner, ASML has brought EUV to High-Volume Manufacturing (HVM). In this context, ASML is pursuing a dual-path approach towards zero reticle defectivity: EUVcompatible pellicle or zero particles towards reticle by advanced particle contamination control. This paper will focus primarily on the approach of advanced particle contamination control and on the understanding of EUV-induced plasma to control both release and transport of particles within the scanner. This paper will present our advancements in understanding and control of particle forces related to the EUV-induced plasma, for EUV sources up to 250W and beyond. This will combine models and simulations with off-line experiments as well as in-situ scanner tests. It will be shown that our understanding of the underlying mechanisms of plasma-induced release and transport of <1um particles enables us to manage defectivity levels down to be compatible with HVM requirements for sub-10nm node lithography.
With the introduction of the NXE:3400B scanner, ASML has brought EUV to High-Volume Manufacturing (HVM). In this context, ASML is pursuing a dual-path approach towards zero reticle defectivity: EUV-compatible pellicle or zero particles towards reticle by advanced particle contamination control. This paper will focus on the latter approach of advanced particle contamination control and will show that we are able to reduce particle contamination towards reticle to a level that is compatible with HVM requirements for sub-10nm node lithography.
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