Doublecoat Planar Polyimide Process
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Multilevel metallization is provided on a substrate, such as a semiconductor substrate, by using two thin polyimide insulation coats or layers on a metal pattern to form a smooth, planar insulating surface and then providing vias with a reflow resist technique. As indicated in Fig. 1, a substrate 10 has a first metal pattern 12 formed thereon. A first coat or layer 14 of polyimide is formed over and between the segments of the first metal pattern 12, followed by a second coat or layer 16 of polyimide formed over the first layer 14. It can be seen that the surface of the first polyimide layer 14 will be somewhat uneven or rough, but the surface of the second polyimide layer 16 is smooth and planar. To provide vias through the polyimide layers 14 and 16 to the first metal pattern 12, the reflow resist technique is employed.