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.

The patterning of the pure polyimide resist (SX AR-P 5000/80) is in this case possible using a two-layer system analogue to AR-P 5400 / AR-P 3500.

For this application, a surprisingly simple procedure was developed:

twolayer

Table 1: Process parameters for the two-layer polyimide process

The double coating can be carried out without any problems. After exposure, development of the photoresist and the polyimide is performed in one step. Removal of the now superfluous photoresist layer can easily be realized by flood exposure and another development step using a weaker developer.

Polyimid-Zweilagen

Image 1: Structures of the pure polyimide after removal of the photoresists, film thickness of 600 nm