Semiconductor device with silicided source/drains
View Patent ↗In a semiconductor device, a relatively deep germanium implant and activation thereof precedes deposition of the nickel for nickel silicide formation. The activation of the germanium causes the lattice constant in the region of the implant to be increased over the lattice constant of the background substrate, which is preferably silicon. The effect is that the lattice so altered avoids formation of nickel disilicide. The result is that the nickel silicide spiking is avoided.
1. A method of forming a contact to a source/drain contact region of a transistor device having a gate, and the source/drain contact region is comprised substantially of silicon, the method comprising:
implanting germanium into a region of the source/drain contact region at a dose between 1E13 and 1E17 atoms per centimeter squared using the gate as a mask;
activating the germanium implanted into the source/drain contact region;
implanting boron into the source/drain contact, wherein the implanting the boron is performed subsequent to the activating the germanium; and
forming a nickel silicide over the source/drain contact region after the activating to form the contact.
2. The method of claim 1 wherein the activating the germanium further includes activating the germanium in order to make the germanium substitutional in a lattice of the source/drain contact region, wherein the lattice includes silicon.
3. The method of claim 1 wherein the activating the germanium increases a lattice constant of the lattice in the source/drain contact region.
4. The method of claim 1 wherein the activating includes heating the source/drain contact region to a temperature of greater than 550 C.
5. The method of claim 1 wherein the activating further includes rapid thermal annealing of the source/drain contact region.
6. The method of claim 1 wherein the activating further includes laser annealing of the source/drain contact region.
7. The method of claim 1 wherein the activating further includes arc lamp thermal annealing of the source/drain contact region.
8. The method of claim 1 wherein the activating further includes gas convection annealing of the source/drain contact region.
9. The method of claim 1 wherein the implanting the is performed at a temperature between 25 and 600 degrees Celsius.
10. The method of claim 1 further comprising:
forming a sidewall spacer adjacent to a sidewall of the gate, wherein the implanting the germanium is performed prior to the forming the sidewall spacer.
11. The method of claim 10 wherein the forming the sidewall spacer is performed prior to the implanting the source/drain dopant.
12. The method of claim 1 wherein the gate is over a semiconductor substrate, the source/drain contact region is in the semiconductor substrate, and the source/drain contact region is disposed laterally from the gate.
13. The method of claim 12 further comprising implanting a second source/drain dopant in the semiconductor substrate after the implanting the source/drain dopant, wherein the second source/drain dopant is implanted deeper than the source/drain dopant.
14. The method of claim 12 wherein the implanting the germanium further includes implanting with an energy of at least 3 keV.
15. The method of claim 12 wherein the implanting the germanium further includes implanting with an energy in the range of 3 keV to 50 keV.
16. The method of claim 12 wherein the implanting the partieles germanium is performed at a temperature between 25 and 600 degrees Celsius.
17. The method of claim 1 , wherein:
the transistor has a second source/drain contact;
the implanting of the further includes implanting the germanium into the second source/drain contact region at the dose between 1E13 and 1E17 atoms per centimeter squared;
the activating of the germanium further includes activating the germanium implanted into the second source/drain contact region;
the implanting boron further includes implanting the boron into the second source/drain contact region; and
forming a second nickel silicide over the second region to form a second contact.
18. The method of claim 1 , wherein the gate is over a semiconductor substrate and a channel is in the substrate under the gate, further comprising forming a source/drain extension adjacent to the channel in the semiconductor substrate.
19. The method of claim 18 , wherein the forming comprises implanting a second source/drain dopant into the substrate for forming the source/drain extension, wherein the implanting the second source/drain dopant is performed prior to the implanting the boron.
20. The method of claim 1 further comprising activating the boron.
21. A method of forming a contact to a source/drain contact region of a transistor device having a gate, and the source/drain contact region is comprised substantially of silicon, the method comprising:
implanting germanium into a region of the source/drain contact region at a dose between 1E13 and 1E17 atoms per centimeter squared using the gate as a mask;
activating the germanium implanted into the source/drain contact region;
implanting boron into the source/drain contact, wherein the implanting the boron is performed subsequent to the activating the germanium; and
forming a nickel silicide over the source/drain contact region after the activating to form the contact;
wherein the activating includes heating the source/drain contact region to a temperature of greater than 1000 C.
22. A method of forming a contact to a source/drain contact region of a transistor device having a gate, and the source/drain contact region is comprised substantially of silicon, the method comprising:
implanting germanium into a region of the source/drain contact region at a dose between 1E13 and 1E17 atoms per centimeter squared using the gate as a mask;
activating the germanium implanted into the source/drain contact region;
implanting boron into the source/drain contact, wherein the implanting the boron is performed subsequent to the activating the germanium; and
forming a nickel silicide over the source/drain contact region after the activating to form the contact;
wherein the activating further includes heating the source/drain contact region to a temperature in a range of approximately 900-1400 C.
23. A method of forming a semiconductor device, the method comprising:
forming a gate over a silicon substrate, the substrate having a lattice constant;
increasing the lattice constant of the lattice in a source/drain region of the substrate after the forming the gate by implanting germanium at a dose between 1E13 and 1E17 using the gate as a mask;
implanting a boron into the source/drain region, wherein the implanting the boron is performed subsequent to the increasing the lattice constant; and
forming a nickel silicide over the portion of the source/drain region.
24. A method of forming a semiconductor device, the method comprising:
forming a gate over a silicon semiconductor substrate;
implanting particles including germanium into a region of the substrate after the forming the gate at a dose between 1E13 and 1E17 atoms per centimeter squared using the gate as a mask;
activating the germanium implanted into the region;
implanting boron into the substrate for forming at least a portion of a source/drain region in the substrate, wherein the implanting the boron is performed subsequent to the activating the germanium; and
forming a nickel silicide over the region after the activating.
25. In a transistor device structure having a gate stack and source/drain contact regions comprised primarily of a first material, wherein the source/drain contact regions have a lattice constant, a method of forming a contact, comprising:
implanting germanium at a dose between 1E13 and 1E17 atoms per centimeter squared into the source/drain contact regions using the gate stack as a mask;
activating the germanium implanted into the source/drain contact regions to increase the lattice constant of the source/drain contact regions;
implanting boron into the source/drain contact regions after the step of activating; and
forming a nickel silicide over the source/drain contact regions after the step of activating.