[DougMerritt]

> Crazy they have physical masks with features as small as 7nm.

Everything about this is crazy complex, and the state of the art in any given year is also secret to TSMC and other tiny-feature-size fabs.

But in addition to gradually upping the narrow-bandwidth/phase-coherent illumination frequency every year (which has many problems but continues to see continual progress), they've also long been using techniques to work around the diffraction limit/resolution barrier [1], such as subwavelength metamaterial "hyperlenses" / "superlenses" (previously widely thought to be impossible even in theory) [2][3] and "assist features" and other non-traditional masking elements to pre-compensate for imaging distortions [4]. Plus they fiddle a lot with the chip process to tune it in weird ways to assist with or compensate for the previous issues.

[1] https://en.wikipedia.org/wiki/Diffraction-limited_system

[2] https://en.wikipedia.org/wiki/Superlens#Theory

[3] "Subwavelength-Grating Metamaterial Structures for Silicon Photonic Devices" https://ieeexplore.ieee.org/document/8424820

[4] https://en.wikipedia.org/wiki/Extreme_ultraviolet_lithograph...