Single process for linear and metal fill
After forming a contact opening in a dielectric material layer located over a substrate, a metal liner layer comprising a nitride of an alloy and a metal contact layer comprising the alloy that provides the metal liner layer are deposited in-situ in the contact opening by sputter deposition in a single process and without an air break. Compositions of the metal liner layer and the metal contact layer can be changed by varying gas compositions employed in the sputtering process.
1. A method of forming a semiconductor structure comprising:
forming a sacrificial gate structure straddling a portion of a semiconductor fin located over a substrate, the sacrificial gate structure comprising a sacrificial gate stack and a gate spacer located on sidewalls of the sacrificial gate stack;
forming an interlevel dielectric (ILD) layer laterally surrounding the sacrificial gate structure;
removing the sacrificial gate stack to provide a gate cavity;
forming a gate dielectric layer along sidewalls and a bottom surface of the gate cavity and on a top surface of the ILD layer;
forming a first metal liner layer on the gate dielectric layer by sputtering at least one target comprising components of an alloy selected from the group consisting of TiAl, MgAl, MgTi, MgV and AlV in a hydrocarbon-containing sputtering atmosphere in a sputtering apparatus;
without an air break to expose the first metal liner layer to an oxygen-containing atmosphere, forming a second metal liner layer on the first metal liner layer by sputtering the at least one target in a nitrogen-containing sputtering atmosphere; and
without an air break to expose the second metal liner layer to the oxygen-containing atmosphere, forming a metal gate layer on the second meal liner layer by sputtering the at least one target in a nitrogen-free sputtering atmosphere.
2. The method of claim 1 , wherein the hydrocarbon-containing sputtering atmosphere consists of hydrocarbon and argon.
3. The method of claim 2 , wherein the hydrocarbon comprises methane, ethane or ethylene.
4. The method of claim 1 , wherein the nitrogen-containing sputtering atmosphere consists of nitrogen and argon.
5. The method of claim 1 , wherein the nitrogen-free sputtering atmosphere consists of argon.
6. The method of claim 1 , wherein the first metal liner layer comprises a metal carbide selected from the group consisting of TiAlC, MgAlC, MgTiC, MgVC and AlVC.
7. The method of claim 1 , wherein the second metal liner layer comprises a metal nitride selected from the group consisting of TiAlN, MgAlN, MgTiN, MgVN and AlVN.
8. The method of claim 1 , wherein the metal gate layer comprises an alloy selected from the group consisting of TiAl, MgAlC, MgTiC, MgVC and AlVC.
9. The method of claim 1 , further comprising forming a work function metal layer on the gate dielectric layer prior to the forming the first metal liner layer.