Non-plasma capping layer for interconnect applications
View Patent ↗The present invention provides an interconnect structure which has a high leakage resistance and substantially no metallic residues and no physical damage present at an interface between the interconnect dielectric and an overlying dielectric capping layer. The interconnect structure of the invention also has an interface between each conductive feature and the overlying dielectric capping layer that is substantially defect-free. The interconnect structure of the invention includes a non-plasma deposited dielectric capping layer which is formed utilizing a process including a thermal and chemical-only pretreatment step that removes surface oxide from atop each of the conductive features as well as metallic residues from atop the interconnect dielectric material. Following this pretreatment step, the dielectric capping layer is deposited.
1. A method of fabricating an interconnect structure comprising:
providing a structure including a dielectric material having a plurality of conductive features embedded therein, each of said plurality of conductive features includes a surface oxide layer, and said dielectric material having an upper surface that contains metallic residues thereon;
subjecting said structure to a thermal and chemical-only pretreatment step which removes said surface oxide layer and said metallic residues from said structure, said thermal and chemical only pretreatment step comprises heating the structure in a reducing ambient including a H 2 -containing atmosphere, a NF 3 -containing atmosphere or a mixture thereof, without the presence or generation of any plasma; and
forming a dielectric capping layer on a bare upper surface of each of said plurality of conductive features and on a bare upper surface of said dielectric material.
2. The method of claim 1 wherein said reducing ambient is said H 2 -containing atmosphere.
3. The method of claim 1 wherein said reducing ambient is said NF 3 -containing atmosphere.
4. The method of claim 1 wherein said thermal and chemical-only pretreatment step is performed at an elevated temperature that is within a range from about 100° to about 500° C.
5. The method of claim 4 wherein said temperature is in a range from about 150° to about 450° C.
6. The method of claim 1 wherein said thermal and chemical-only pretreatment step is performed for a period of time from about 1 to about 20 minutes.
7. The method of claim 6 wherein said period of time is from about 2 to about 5 minutes.
8. The method of claim 1 wherein said structure further includes a U-shaped diffusion barrier separating each of said plurality of conductive features from said dielectric material.
9. The method of claim 1 wherein said forming the dielectric capping layer is performed in a same tool as that of said thermal and chemical-only pretreatment step.
10. The method of claim 1 wherein said forming the dielectric capping layer is performed in a different tool as that of said thermal and chemical-only pretreatment step.
11. The method of claim 1 wherein each of said plurality of conductive features comprises Cu or a Cu-containing alloy.
12. A method of fabricating an interconnect structure comprising:
providing a structure including a dielectric material having a plurality of Cu-containing conductive features embedded therein, each of said Cu-containing conductive features includes a surface oxide layer, and said dielectric material having an upper surface that contains metallic residues thereon;
subjecting said structure to a thermal and chemical-only pretreatment step which removes said surface oxide layer and said metallic residues from said structure, said thermal-only pretreatment step comprises heating the structure at a temperature from about 100° to about 500° C. in a H 2 -containing or NF 3 -containing reducing ambient, without the presence or generation of any plasma; and
forming a dielectric capping layer in a same tool as said thermal-only pretreatment step on a bare upper surface of each of said plurality of conductive features and on a bare upper surface of said dielectric material.
13. A method of fabricating an interconnect structure comprising:
providing a structure including a dielectric material having a plurality of conductive features embedded therein, each of said plurality of conductive features includes a surface oxide layer, and said dielectric material having an upper surface that contains metallic residues thereon;
subjecting said structure to a thermal and chemical-only pretreatment step, without the presence or generation of any plasma, which removes said surface oxide layer and said metallic residues from said structure, said thermal and chemical only pretreatment step comprises heating the structure in a reducing ambient of a H 2 and N 2 atmosphere, or a H 2 and NH 3 atmosphere; and
forming a dielectric capping layer on a bare upper surface of each of said plurality of conductive features and on a bare upper surface of said dielectric material.