Plasma Etching of Polyimide Through an Aluminum Mask
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Plasma etching of polyimide through an aluminum mask in an oxidizing atmosphere enables the entire mask to be converted to oxide and removed by a back door etch process. Alternatively, the thickness of aluminum can be increased so that some metal remains to protect the polyimide during subsequent RF sputter cleaning and to enable direct deposition of second level aluminum metallization. As shown in Fig. 1, an aluminum mask 10 of around 250-400 A thickness is used to define via holes 11 through a polyimide insulation layer 12 to enable contact with a first level aluminum metallization level 13 on the surface of wafer 9. Both aluminum layers are covered with thin layers 14 and 15 of native oxide.