What makes an EUV scanner tick

Paul van Gerven
Leestijd: 2 minuten

The principles that underlie an EUV scanner are the same as for every optical scanner – but their execution is completely different.

1. Producing EUV light

A kind of inkjet nozzle produces forty thousand minuscule droplets of molten tin per second. As it falls, each droplet is shot twice by a laser. The first, relatively weak pulse deforms the droplet into a pancake; the second, much harder punch vaporizes it and creates a plasma, which emits EUV light in a fairly broad wavelength range. EUV optics (see step 2) around the plasma prefilter the light and concentrate it to a focal point located precisely at the border of the source and the machine. Inside the machine, the light is filtered again until what’s left is primarily 13.5-nanometre light.

Challenges: 1) Providing sufficient power, by a) efficiently converting the laser energy into EUV light and b) efficiently guiding the light to the scanner. 2) Making sure no debris damages the delicate collector. ASML uses a curtain of hydrogen for this.

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