General exposure wavelengths for broadband UV-lithography are in a range between 300 nm and 450 nm, which includes the important lines of high-pressure mercury lamp at 436 nm (g-line), 405 nm (h-line) and 365 nm (i-line). The state-of-the-art technologies are currently determined by g-line and i-line wavelength ranges.
The most important wavelength of 488 nm and the less frequently used 532 nm wavelength are not covered by standard photoresists – in this case, optimized positive-tone resists are required. If a modified photosensitive compound (PSC) and a higher concentration of this PSC are used, the UV- absorption spectrum slightly shifts towards the longer wavelengths.
Even though the absorption at 488 nm is still below < 0.05 is, absorption is sufficient to expose and to pattern a resist at this wavelength. Sensitivity however is low under these conditions and stated to be > 1.000 mJ/cm² for a layer of 1 µm. A few users reported that a patterning was also possible with an exposure at 532 nm. The light dose required was in the range of > 3 J/cm. (see SX AR-P 3500/7)
Overview Photoresists- Positive