Method for forming germanides and devices obtained thereof
View Patent ↗The present invention discloses a method for forming germanides on substrates with exposed germanium and exposed dielectric(s) topography, thereby allowing for variations in the germanide forming process. The method comprises the steps of depositing nickel on a substrate having topography, performing a first thermal step to convert substantially all deposited nickel in regions away from the topography into a germanide, selectively removing the unreacted nickel, and performing a second thermal step to lower the resistance of formed germanide.
1. A method for forming a nickel-germanide on a substrate, comprising:
providing a substrate comprising an exposed germanium area bordering a dielectric area;
depositing nickel over the substrate;
performing a first thermal process step for which a first thermal budget is selected to convert, in center regions of the germanium area, substantially all metal into a nickel-germanide;
selectively removing unreacted metal; and
performing a second thermal process step for which a second thermal budget is selected to lower a resistance of the formed germanide layer;
wherein the nickel-germanide formed during the first thermal process step comprises metal-rich germanide phases and the nickel-germanide formed during the second thermal process step consists essentially of a mono-nickel mono-germanium (NilGel) phase.
2. The method of claim 1 , wherein the dielectric area is a field isolation region or a spacer.
3. The method of claim 1 , wherein the germanide layer formed during the first thermal process step is predominantly a metal-rich germanide.
4. The method of claim 1 , wherein the germanide-forming metal comprises nickel.
5. The method of claim 4 , wherein the germanide-forming metal is nickel.
6. The method of claim 1 , wherein a temperature of the first thermal step is in a range of 150° C. to 325° C., for a time period in a range of nearly 0 seconds to 300 seconds.
7. The method of claim 1 , wherein a temperature of the first thermal step is in a range of 200° C. to 270° C., for a time period in a range of 10 seconds to 60 seconds.
8. The method of claim 1 , wherein a temperature of the second thermal step is in a range of 300° C. to 550° C., for a time period in a range of nearly 0 seconds to 300 seconds.
9. The method of claim 1 , wherein a temperature of the second thermal step is in a range of 325° C. to 400° C., for a time period in a range of 10 seconds to 60 seconds.
10. A method for forming a germanide on a substrate, comprising:
providing a substrate comprising an exposed germanium area bordered by a dielectric area;
depositing nickel over the substrate;
performing a first thermal process step for which a first thermal budget is selected to convert, in regions of the germanium area away from the dielectric area, substantially all nickel into a nickel-germanide and to limit diffusion of germanium over the dielectric area;
selectively removing unreacted nickel; and
performing a second thermal process step for which a second thermal budget is selected to lower a resistance of the formned nickel-germanide layer;
wherein the nickel-germanide formed during the first thermal process step comprises metal-rich germanide phases and the nickel-germanide formed during the second thermal process step consists essentially of a mono-nickel mono-germanium (NilGel) phase.
11. A method for forming a nickel-germanide on a substrate, comprising:
providing a substrate comprising an exposed germanium area bordering a dielectric area;
depositing nickel over the substrate;
performing a first thermal process step for which a first thermal budget is selected to convert, in center regions of the germanium area, substantially all metal into a nickel-germanide;
selectively removing unreacted metal; and
performing a second thermal process step for which a second thermal budget is selected to lower a resistance of the formed germanide layer;
wherein the nickel-germanide formed during the first thermal process step comprises metal-rich germanide phases and the nickel-germanide formed during the second thermal process step consists essentially of a mono-nickel mono-germanium (Ni l Ge l ) phase.
12. The method of claim 11 , wherein the dielectric area is a field isolation region or a spacer.
13. The method of claim 11 , wherein the germanide layer formed during the first thermal process step is predominantly a metal-rich germanide.
14. The method of claim 11 , wherein the germanide-forming metal comprises nickel.
15. The method of claim 14 , wherein the germanide-forming metal is nickel.
16. The method of claim 11 , wherein a temperature of the first thermal step is in a range of 150° C. to 325° C., for a time period in a range of nearly 0 seconds to 300 seconds.
17. The method of claim 11 , wherein a temperature of the first thermal step is in a range of 200° C. to 270° C., for a time period in a range of 10 seconds to 60 seconds.
18. The method of claim 11 , wherein a temperature of the second thermal step is in a range of 300° C. to 550° C., for a time period in a range of nearly 0 seconds to 300 seconds.
19. The method of claim 11 , wherein a temperature of the second thermal step is in a range of 325° C. to 400° C., for a time period in a range of 10 seconds to 60 seconds.