Lithography Glossary

Written by Chris Mack
Brought to you by the creators of PROLITH

Nanolithography
Lithography involving the printing of ultra small features, typically on the order of nanometers in size.

Example: Nanolithography techniques are being used to research possible device technologies of the future.

Negative Photoresist
A photoresist whose chemical structure allows for the areas that are exposed to light to develop at a slower rate than those areas not exposed to light.

Example: In theory, isolated lines or islands are best printed in negative photoresist, whereas spaces and contacts prefer a positive resist.

NGL
Next Generation Lithography, any potential successor to optical lithography for semiconductor manufacturing.

Example: Despite billions of dollars invested in NGL technologies over the last two decades, optical lithography is still the only viable manufacturing technology for the foreseeable future.

NILS
see Normalized Image Log-Slope

Normalized Image Log-Slope (NILS)
The slope of the logarithm of an aerial image, measured at the desired photoresist edge position, normalized by multiplying by the nominal resist feature width. Generally, the sign of the slope is adjusted to be positive when the image is sloping in the correct direction. See also Image Log-Slope.

Example: The NILS is a popular image metric because it is directly proportional to the feature's exposure latitude.

Numerical Aperture (NA)
The sine of the maximum half-angle of light that can make it through a lens, multiplied by the index of refraction of the media.

Example: The numerical aperture of the lens can be adjusted over a specified range through the use of a motorized iris.