SPIE 9776, 97762D (2016).
In fact, the 32 nm pitch DRAM by EUV will lengthen up to at least 9F2 cell area, where F=active area half-pitch (traditionally, it had been 6F2). >> The coupling between the primary image and the self images is too strong for the asymmetry to be completely eliminated by assist features; only asymmetric illumination can achieve this.
The competition between DUV and EUV systems will be decided more by economic and technological factors such as risk, time and cost of development and cost of ownership. Such variations could not be detected by wide-area reflectivity measurements, but would be significant on the scale of the critical dimension (CD). SPIE 7969, 79691N (2011). Wouldn't it be easier to develop this EUV technology more iteratively and gradually improve and fix all the problems (light source, power, availability, pellicles, mirrors, etc.)  Besides the more complicated effects due to shadowing and pupil rotation, tilted edges are converted to stair shape, which may be distorted by OPC.  At sufficient doses 40 eV electrons are known to penetrate 180 nm thick resist leading to development. What is a proper way to support/suspend cat6 cable in a drop ceiling?
David M. Williamson, "DUV or EUV: that is the question," Proc.
With the natural Poisson distribution due to the random arrival and absorption times of the photons, there is an expected natural dose (photon number) variation of at least several percent 3 sigma, making the exposure process susceptible to stochastic variations. H. J. Levinson and T. A. Brunner, Proc.
SPIE 4691, 476 (2002). %����  With the blank peak-to-valley spec of 50 nm, ~1.25 nm image placement error is possible.
A. Narasimhan et al., "Mechanisms of EUV Exposure: Internal Excitation and Electron Blur", EUV Symposium 6/16/2016, p.11.  The ions absorb the EUV light they emit, and are easily neutralized by electrons in the plasma to lower charge states which produce light mainly at other, unusable wavelengths, which results in a much reduced efficiency of light generation for lithography at higher plasma power density. Although the azimuthal angle range is +/- ~20° (NXE3400 field data indicate 18.2°) on 0.33 NA scanners, at 7nm design rules (36-40 nm pitch), the tolerance for illumination can be +/-15°, or even less.
 Assist features may also get in the way of access to power/ground rails. 22, 30623 (2014).
 Unfortunately, hardmask layers tend to increase photoelectron emission, degrading the depth of focus. Mat.
At present, there is no great pellicle material for EUV ( detonation, acetylene etc) so down time is significant. Extreme ultraviolet (EUV) lithography is a soft X-ray technology, which has a wavelength of 13.5nm. , The power target for EUV lithography is at least 250 W, while for other conventional lithography sources, it is much less.