This is a difficult one, I'm really excited about lithography and want to share my knowledge but since I'm working at one of those firms (dislcaimer here) I can share little...

So, let's stay safe and share some public knowledge:

1) The article mentions source power being a major factor and a huge improvement has been the addition of the prepulse (pancake). Here a great video showing how this concept works: https://www.youtube.com/watch?v=bRbHDtPbHe0

2) Short, beginners level, introduction how the EUV source works (note: this movie is made before ASML tookover Cymer, so some history here): https://www.cymer.com/euv-lithography/how-an-euv-light-sourc...

3) Chris Mack's coverage of the last SPIE conferences give a nice summary of the field: http://www.lithoguru.com/scientist/conferences.html Note that Mack is an EUV-sceptic, his views on EUV are not commonly shared.