Sensitive negative PMMA resist (CAR)

PMMA resist are mainly used for electron beam applications or as protective coatings in aggressive wet chemical etching procedures. In principle, also a structuring of PMMA layers with deep UV exposure (220-266 nm) is possible, but the sensitivity is in this case low and long exposure times are consequently required.

Development of thick negative resist layer

If the negative resist AR-N 4400-50 is utilised, resist layers of >200 µ m can be built up in repeated coating steps (see product information of CAR 44). Decisive for the quality of the layers to be obtained is the bake procedure.

Chemically enhanced negative resist (Process parameters and resolution)

Process parameters, sensitivity, resolution, edge quality and dimensional stability are exemplarily shown for AR-N 4340. Investigations were performed on 150mm-wafers with Si-surface.

Negative two- layer lift-off system

Positive two-layer systems have been on the market for a long time (see positive two-layer lift-off systems). Now there are also versions with negative resists as top resist. The greatest advantage of this innovation is the higher thermal stability of negative resists.

Negative polyimide photoresist

As an alternative to the positive polyimide resist (SX AR-PC 5000/82.7) which is already a polyimide in dissolved form and thus requires no curing process (see “Positive polyimide resist”)

Spray resists for different topologies (negative)

Allresist furthermore offers various negative-tone resists for spray coating applications which are described in detail in this section (see Spray resists for different topologies (positive and negative)

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.