Dry etchback of interconnect contacts
View Patent ↗A method and structure for a composite stud contact interface with a decreased contact resistance and improved reliability. A selective dry etch is used which comprises a fluorine containing gas. The contact resistance is reduced by partially dry-etching back the tungsten contact after or during the M1 RIE process. The recessed contact is then subsequently metalized during the M1 liner/plating process. The tungsten contact height is reduced after it has been fully formed.
1. A method of making an electronic device comprising the steps of:
providing a substrate on which contacts are to be formed;
providing a conductive via comprised of a first conductive material formed in an oxide on said substrate;
providing a dielectric layer on said conductive via;
providing an oxide layer on said dielectric layer;
providing a photoresist layer on said oxide layer;
forming openings in said photoresist layer;
removing said photoresist layer and removing in said openings said dielectric layer and said oxide layer and a portion of said first conductive material with a fluorine containing gas;
depositing a second conductive material in said openings to form a composite conductive via comprising said first conductive material and said second conductive material.
2. The method of claim 1 wherein said fluorine containing gas is selected from the group consisting of NF3, F2 and SF6.
3. The method of claim 1 wherein said dielectric layer is a low-K SiCOH material.
4. The method of claim 3 wherein said low-K SiCOH material is a porous ultra low-K material.
5. The method of claim 1 wherein said first conductive material in Tungsten and said second conductive material is Copper.
6. The method of claim 2 wherein said fluorine containing gas removal comprises approximately 500 sccm of Argon and approximately 50 sccm of NF3.
7. The method of claim 6 wherein said fluorine containing gas removal further comprises approximately 10 sccm O2 and 50 sccm of CH2F2 or CH3F.
8. The method of claim 6 wherein said fluorine containing gas removal pressure is approximately 100 mTorr to approximately 200 mTorr.