Just recently coated resist films still contain a substantial amount of residual solvent, depending on the respective film thickness. The subsequent bake step at 90 – 100 °C is performed in order to dry the resist films,
Concentrated oxidising acids (sulphuric acid, nitric acid, aqua regia 1) , piranha 2) ) attack resist films already at room temperatures and are often used as remover for persistent resist structures.
The exposure is performed using masks in suitable exposure systems such as e.g. steppers (i-, g-line), mask aligners or contact exposure systems in the appropriate spectral working range.
With respect to the source materials used, e-beam resists fall into two different categories: PMMA resists (AR-P 6000) Novolak resists (AR-N/P 7000) » The general rule is that with increasing bake-
During development, a positive tone resist film is structured by a removal of exposed areas, while unexposed areas are removed when negative resists are used. To achieve reproducible results,
For the removal of softbaked coatings, polar solvents such as e.g. the respective resist thinner AR 300-12 (methoxy propyl acetate = PGMEA) and the remover AR 600-70 (acetone-based)
Protective coatings are available for a large variety of applications, e.g. for the protection of wafer-backsides: or mechanical protection during transport
With image reversal resists such as AR-U 4000, positive or negative tone images can be generated of the optical transmitted pattern depending on the manufacturing process. If the resist is processed according to the general protocol for positive resists without any additional steps,
A variety of one- or two layer systems are available which generate undercut patterns. For example, AR-P 5350 is a one layer system suitable for the production of metallic vapour phase structures.
Coating: As a general rule for the coating with thick positive and negative tone resists, resists should be left undisturbed for several hours up to one day before processing ( » Question 6 Optimum coating parameters,