EUV With Fewer Mirrors?

Has it really been so long since I last did a newsletter? That is kind of crazy. Time moves so fast.

Like as I wrote before, I want to thank Professor Shintake as well as Dr. Patrick Naulleau of EUV Tech for their help and consultation. They are the true experts of this domain.

I do want to note that ASML chose the number of mirrors they did for a very real reason. It gives them full ability to print specific features on the mask. Simplifying the number of mirrors that away so we should keep this in mind. Perhaps fabs in the future adopt a mix of lithography machines - doing some very complicated layers with those machines and others with simpler mirrors.

A mirror inside ASML's EUV lithography machine reflects just 70% of the EUV light it receives.

With 10-12 reflections in the machine, this can get inefficient. Just 1% of the photons hit the wafer. Electrical power efficiency is said to be less than 0.2%.

It also contributes to troublesome stochastic defects, since not enough EUV photons hit the resist to overcome quantum effects.

So a recent paper from Professor Tsumoru Shintake at the Okinawa Institute of Science & Technology caught my eye.

It proposes a simplified setup with radically fewer mirrors. But Shintake makes it clear to me that his system no way challenges ASML's. In fact, it should complement it.

I think this thing can work. In today’s video, I want to walk you through this interesting new thing cooking up in beautiful Okinawa.

Beginnings

We should begin with a brief overview of a commercial EUV lithography system. I am not going to cover everything, just enough to get you through this video.

First, we need EUV light, 13.5 nanometer wavelength light. The light source creates it in a number of ways - lasers hitting tin droplets, particle accelerators, whatever you want.

A mirror then collects the light and sends it through the Illumination module, which spreads out the light and makes it as uniform as possible for the mask.

That light then bounces off a photomask, a special mirror with the chip design printed onto it.

The reflected light then goes through an Optical Projection module that reduces the size of the pattern on the mask's field by some ratio and focuses it.

Finally, the light hits the resist-coated wafer. Ideally at the exact ...