Photolithography is basically shining some kind of electromagnetic radiation through a stencil so that specific lines are etched into the top “photoresist” layer of a silicon wafer. The radiation causes a chemical change wherever a photon hits, so that stencil blocks the photons in a particular pattern.
Photons are subject to interference from other photons (and even itself) based on wavelength, so smaller wavelengths (which are higher energy) can fit into smaller and finer feature size, which ultimately means smaller transistors where more can fit in any given area of silicon.
But once the energy gets too high, as with X-ray photons, there’s a secondary effect that ruins things. The photons have too much leftover energy even after hitting the photoresist to be etched, and it causes excited electrons to cause their own radiation where high energy photons start bouncing around underneath, and then the resulting boundaries between the photoresist that has been exposed to radiation and the stuff that hasn’t becomes blurry and fuzzy, which wrecks the fine detail.
So much of the 20 years leading up to commercialized EUV machines has been about finding the perfect wavelength optimized for feature size, between wavelengths small enough to make really fine details and energy levels low enough not to cause secondary reactions.
No, X-rays are too energetic.
Photolithography is basically shining some kind of electromagnetic radiation through a stencil so that specific lines are etched into the top “photoresist” layer of a silicon wafer. The radiation causes a chemical change wherever a photon hits, so that stencil blocks the photons in a particular pattern.
Photons are subject to interference from other photons (and even itself) based on wavelength, so smaller wavelengths (which are higher energy) can fit into smaller and finer feature size, which ultimately means smaller transistors where more can fit in any given area of silicon.
But once the energy gets too high, as with X-ray photons, there’s a secondary effect that ruins things. The photons have too much leftover energy even after hitting the photoresist to be etched, and it causes excited electrons to cause their own radiation where high energy photons start bouncing around underneath, and then the resulting boundaries between the photoresist that has been exposed to radiation and the stuff that hasn’t becomes blurry and fuzzy, which wrecks the fine detail.
So much of the 20 years leading up to commercialized EUV machines has been about finding the perfect wavelength optimized for feature size, between wavelengths small enough to make really fine details and energy levels low enough not to cause secondary reactions.