High Rate Plasma Etching of Vias in Thick Organic Films
Original Publication Date: 1985-Aug-01
Included in the Prior Art Database: 2005-Feb-19
The technique presented uses nitrous oxide and ozone for plasma etching of vias in thick polyimide films, in integrated circuits, to control vertical-to-lateral aspect ratio and increased throughput. Two techniques are usually used when etching polyimide vias with sloped profiles: i) image transfer of an erodible imaging resist and ii) undercut control using a barrier layer as a mask. Image transfer requires thick imaging resist which has to be developed and baked to produce desired profile. Further, during the entire etching period, the whole wafer is covered with organic materials (polyimide and imaging resist), thus causing unnecessary chemical loading with reduced etch rate. Hence, this technique is slow and difficult to control.