Resist for 488 nm exposure wavelength
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).
Resist for near infrared (NIR)
With the development of photoresists for an exposure in the wavelength range of 500 to 1100 nm using laser light, new procedures became possible. Lithographic processes at an exposure wavelength greater than 480 nm are not possible with standard photoresists.
Two-layer resist system for hydrofluoric acid etching
Hydrofluoric acid etchings, even those in highly concentrated acids (48%), are technologically used despite the high risk involved with HF applications.
Alkali-stable and solvent-stable negative resist
Most novolac-based photoresists are characterized by high etch stability in the presence of acids (except in highly concentrated oxidizing acids or in concentrated hydrofluoric acid
Temperature-stable negative resist
New aqueous-alkali soluble polymers may even outperform novolacs in certain features. Standard novolacs generally melt in a range between 115–130°C. The thicker the resist film, the higher is the impact of this feature on the resist structure.
Lift off (one layer – two layer)
Two procedures are principally possible to manufacture e.g. conducting paths: 1. Etching technique: A thin metal film (e.g. aluminium) is deposited on a wafer (evaporation or sputtering)
1. What are photoresists composed of, and how do they work?
Photoresists (also photo coatings) are primarily used in micro electronics and micro system technologies for the production of µm- and sub-µm structures. These resists are generally deposited by spin coating in a range between 250
2. For how long are photoresists stable, and what are the optimal storage conditions?
Photoresists are light-sensitive, they are affected by light exposure and high temperatures, and age-related changes occur during storage. Resists are therefore filled in light-protected amber glass bottles,
3. How may age-related changes influence the quality of a photoresist?
During storage, red azo dyes develop due to a thermal chemical reaction of the light-sensitive component with the novolak, causing a darkening of the resist. Even small amounts of the dye lead to darkening,
4.What is the optimal pre-treatment of substrates for photoresists?
If new and clean substrates (wafers) are used, a bake at approximately 200 °C for several minutes is sufficient for drying, but the substrates have to be processed quickly afterwards.