Resist Loss Prohibits Elevated EUV Doses
An upper limit of around 120-130 mJ/cm2
As indicated previously [1], higher doses are expected to alleviate stochastic effects in EUV lithography. However, raising doses will result in increased resist loss [2].
Roughly speaking, doubling the dose from the typical values of ~60-70 mJ/cm2 would be projected to completely remove the resist (Figure 1). However, dose increases of this order of magnitude are expected to rein in the stochasticity.
Figure 1. EUV resist decreases linearly with increasing dose, regardless of starting thickness. The dose at which the resist is completely gone is about twice the typically used dose. From [3].
Electrons from the EUV-induced plasma or EUV absorption in the resist can expose parts of the resist which are supposed to be unexposed. The hydrogen in the EUV-induced plasma can also etch the EUV resist to some degree. Metal oxide resists pose the additional complication of scumming at higher doses in the nominally unexposed areas.
Larger pitches (>50 nm), thicker resists, lower doses look like the direction to go, pushing EUV toward comparable practical resolution with DUV (~80 nm pitch).
References
[1] Stochastic Effects Blur the Resolution Limit of EUV Lithography