| US 7,541,277 B1 | ||
| Stress relaxation, selective nitride phase removal | ||
| Kevin Shawn Petrarca, Newburgh, N.Y. (US); John Charles Petrus, Stanfordville, N.Y. (US); Karl W. Barth, Poughkeepsie, N.Y. (US); and Kaushik A. Kumar, Poughkeepsie, N.Y. (US) | ||
| Assigned to International Business Machines Corporation, Armonk, N.Y. (US) | ||
| Filed on Apr. 30, 2008, as Appl. No. 12/112,457. | ||
| Int. Cl. H01L 21/4763 (2006.01) | ||
| U.S. Cl. 438—619 [438/618; 438/620; 438/621; 438/622; 438/623] | 1 Claim |
| 1. Method for forming a dielectric cap layer over an interconnect layer formed by a back-end-of-the-line (BEOL) interconnect
process, the interconnect process including: lithography, reactive ion etching (RIE), metal filling of conductors, and chemical-mechanical
polishing (CMP), wherein a sacrificial material resides between conductors of the interconnect layer, and wherein the dielectric
cap layer is made porous through an oxidation process including RIE, the method comprising:
depositing a first insulating material on a substrate having a plurality of logic elements formed thereon;
performing a first RIE process using CF4 and O2 with a concentration between 2-5% H2O to achieve a humidity in the O2 using at least one of a bubbler and an atomizer to cause a roughening of a surface of the first insulating material and to
create openings having a thickness between 5-30 nanometers in the first insulating material;
forming the dielectric cap layer by depositing a silicon nitride (SixNy) cap layer to a thickness of between 100-250 Angstroms on the first insulating material;
performing a second RIE process using CF4 and O2 with a concentration between 2-5% H2O to achieve a humidity in the O2 using at least one of a bubbler and an atomizer to cause a roughening of a surface of the SixNy cap layer and to create openings having a thickness between 5-30 nanometers in the SixNy cap layer;
evacuating a sacrificial material between the conductors of the interconnect layer; and
depositing a second insulating material to seal the SixNy cap layer, wherein a subsequent air-bridge is formed below the second insulating material while not filling the air-gap.
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