A dielectric for aluminum and copper metalizations is stable at high temperatures. Surprisingly, in spite of the elimination of water during the cyclization, the polymeric dielectrics are very suitable for filling narrow trenches. The filled trenches exhibit no defects and bubbles or cracks. The polybenzoxazoles have dielectric constants of k≦2.7 and are suitable as an electrical insulator. Furthermore, these materials adhere very well on all surfaces relevant for micro-electronics.