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.
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.
Polyimides are produced by polycondensation of tetracarboxylic dianhydrides and diamines. For highest thermal strain only polyimides are suitable which contain aromatic building blocks in the polymer chain.
In the CiS Institute for Microsensors, deep silicon etch grooves are structured for the fabrication of customer-specific components. For this purpose, a coating procedure via spray coating was developed.
Teflon or similar products are, due to their extreme surface properties, utilised for applications in which a structuring of the Teflon is sometimes desirable. The hydrophobic surface properties however impede the coating with resist,
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”)
PMMA resists can also be patterned using UV-lithography, but only at exposure wavelengths of 200 – 270 nm (deep UV light). Typically used is the wavelength-range of the lowest line of high-pressure mercury lamps at 254 nm.
In certain applications it is desirable to keep the original properties of a polymer unchanged, e.g. without addition of light-sensitive components like for example for a use as moisture sensor.
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)
Spray resists available to date (AZ 4999) are designed for extreme topologies, which means that even vertical silicon trench sidewalls can be covered with resist. These excellent features however come at a price: