For the so-called “2nm” node or beyond, the minimum metal pitch is expected to be 20 nm or even less, while at the same time, contacted gate pitch is being pushed to 40 nm [1]. Therefore, we expect via connections that can possibly be as narrow as 10 nm (Figure 1)! For this reason, it is natural to expect High-NA EUV lithography as the go-to
Dosing for EUV lithography walks a fine line between productivity and defectivity. Fabs can choose higher-dose exposures to suppress photon shot noise [1]. However, higher doses require EUV machines to scan the wafer at slower speeds, degrading throughput [2].
On the other hand, there is the threat of resist thickness loss that… Read More
EUV resists are a key component in the implementation and optimization of EUV lithography. By converting a limited number of absorbed EUV photons into a variable number of released migrating electrons, the resist becomes the final determinant of resolution. There are two kinds of resist which are seriously considered: chemically… Read More
The topics of stochastics and blur in EUV lithography has been examined by myself for quite some time now [1,2], but I am happy to see that others are pursuing this direction seriously as well [3]. As advanced node half-pitch dimensions approach 10 nm and smaller, the size of molecules in the resist becomes impossible to ignore for… Read More
In High-NA EUV lithography systems, the numerical aperture (NA) is expanded from 0.33 to 0.55. This change has been marketed as allowing multi-patterning on the 0.33 NA EUV systems to be avoided. Only very recently have specific examples of this been provided [1]. In fact, it can be shown that double patterning has been implemented… Read More
A comprehensive update to the EUV stochastic image model
In extreme ultraviolet (EUV) lithography, photoelectron/secondary electron blur and secondary electron yield are known to drive stochastic fluctuations in the resist [1-3], leading to the formation of random defects and the degradation of pattern fidelity at advanced
In a DRAM chip, the memory array contains features which are the most densely packed, but at least they are regularly arranged. Outside the array, the regularity is lost, but in the most difficult cases, the pitches can still be comparable with those within the array, though generally larger. Such features include the lowest metal… Read More
Electron blur, stochastics, and now polarization, are all becoming stronger influences in EUV lithography as pitch continues to shrink
As EUV lithography continues to evolve, targeting smaller and smaller pitches, new physical limitations continue to emerge as formidable obstacles. While stochastic effects have long been… Read More
With half-pitch approaching 10 nm, EUV patterning is heavily impacted by stochastic effects, which are aggravated from reduced image contrast from electron blur [1]. A two-mask (“LELE”: Litho-Etch-Litho-Etch) approach was proposed to pattern core features for self-aligned double patterning (SADP)… Read More
Peak probability at zero distance actually makes no sense
In lithography, it is often stated that the best resolution that can be achieved depends on wavelength and numerical aperture (NA), but this actually only applies to the so-called “aerial” image. When the image is actually formed in the resist layer, it also depends on an… Read More
