[on_the_train]

It really is the specific wavelength. Higher or lower is easier. But euv has tricky properties which make it feasible for Lithography (although just barely it you have a look at the optics) but hard to produce with high intensities.

[formerly_proven]

Specifically, what makes x-rays easy to generate are these: https://en.wikipedia.org/wiki/Characteristic_X-ray In essence, smashing electrons into atoms allows you to ionize the inner shell of an atom and when an electron drops down from an outer shell, the excess energy is shed as high-energy photons. This constrains the energy range of X-ray tubes ("smash electron into metal") to wavelengths well below 13.5nm.

(These emission lines are also what is being used in x-ray spectroscopy to identify elements)

[s0rce]

You can also generate broad spectrum bremsstrahlung radiation easily, this is widely used for medical X-rays.

[YetAnotherNick]

Any source to this? I am hearing this for the first time.

[s0rce]

ITs easy to make X-rays, you just hit a metal target with electrons: https://en.wikipedia.org/wiki/X-ray_tube

[YetAnotherNick]

You can hit metal the same way for EUV.

[on_the_train]

No you can't, or rather you only get a tiny amount in the correct wavelengths

[s0rce]

I assume this doesn't work well otherwise everyone would be doing it.