Atomic layer deposition methods and structures thereof
A method and structure for providing a pre-deposition treatment (e.g., of a work-function layer) to accomplish work function tuning. In various embodiments, a gate dielectric layer is formed over a substrate and a work-function metal layer is deposited over the gate dielectric layer. Thereafter, a fluorine-based treatment of the work-function metal layer is performed, where the fluorine-based treatment removes an oxidized layer from a top surface of the work-function metal layer to form a treated work-function metal layer. In some embodiments, after performing the fluorine-based treatment, another metal layer is deposited over the treated work-function metal layer.
1. A method of semiconductor device fabrication, comprising:
forming a gate dielectric layer over a substrate;
depositing a work-function metal layer over the gate dielectric layer;
performing a fluorine-based treatment of the work-function metal layer, wherein the fluorine-based treatment removes an oxidized layer from a top surface of the work-function metal layer to form a treated work-function metal layer; and
after performing the fluorine-based treatment, depositing another metal layer over the treated work-function metal layer.
2. The method of claim 1 , wherein the performing the fluorine-based treatment and the depositing another metal layer are performed in-situ, while maintaining the substrate under a vacuum condition.
3. The method of claim 1 , wherein the fluorine-based treatment includes a precursor including at least one of NF x , TiF x , and WF x , wherein x is between approximately 1 and approximately 6.
4. The method of claim 1 , wherein the work-function metal layer includes at least one of TiN, TaN, TiAlC, TiAl, TiSiN, TaSi, and TiAlN.
5. The method of claim 1 , wherein the work-function metal is deposited at a temperature from approximately 200 degrees Celsius to approximately 600 degrees Celsius.
6. The method of claim 1 , wherein the fluorine-based treatment includes a thermal chemical reaction between a F-based metal precursor and the oxidized layer of the work-function metal layer, and wherein the thermal chemical reaction serves to remove the oxidized layer.
7. The method of claim 6 , wherein the thermal chemical reaction is performed at a temperature from about 100-1000° C., and wherein a F-based metal precursor flow rate is about 100-8000 sccm.
8. The method of claim 1 , wherein the fluorine-based treatment includes a plasma treatment including a plasma generated using a F-based metal precursor, and wherein the oxidized layer of the work-function metal layer is removed by the plasma treatment.
9. The method of claim 8 , wherein the plasma treatment is performed at a temperature from about 20-200° C., wherein a F-based metal precursor flow rate is about 5-500 sccm, and wherein a plasma power is about 10-1000 Watts.
10. The method of claim 8 , wherein the F-based metal precursor includes an NF 3 metal precursor, wherein the plasma generates NF 3 radicals, and wherein the NF 3 radicals remove the oxidized layer of the work-function metal layer.
11. The method of claim 10 , wherein a number of NF 3 radicals are increased by increasing at least one of a duration of the fluorine-based treatment, a precursor flow rate, and a processing temperature.
12. The method of claim 1 , wherein the fluorine-based treatment reduces a thickness of the work-function metal layer.
13. A method of semiconductor device fabrication, comprising:
forming a gate dielectric layer over a substrate;
forming a barrier layer over the gate dielectric;
generating a plasma using a fluorine-based precursor and exposing the barrier layer to the plasma;
responsive to exposing the barrier layer to the plasma, removing an oxide layer from a surface of the barrier layer; and
after removing the oxide layer, depositing another metal layer over the barrier layer.
14. The method of claim 13 , wherein the barrier layer includes a work-function metal layer.
15. The method of claim 13 , wherein the barrier layer includes TaN.
16. The method of claim 13 , wherein the another metal layer a TiAlC layer.
17. The method of claim 16 , further comprising depositing a TiN layer over the TiAlC layer.
18. The method of claim 13 , wherein plasma includes a remote plasma, wherein the fluorine-based precursor includes NF 3 , wherein the remote plasma generates NF 3 radicals, and wherein the barrier layer is exposed to the generated NF 3 radicals, thereby removing the oxide layer.
19. A method, comprising:
depositing, under a vacuum condition, a work-function metal layer over a gate dielectric layer;
while maintaining the vacuum condition, performing a fluorine-based treatment of the work-function metal layer, wherein the fluorine-based treatment includes at least one of NF x , TiF x , and WF x , and wherein the fluorine-based treatment removes an oxidized layer from a top surface of the work-function metal layer to form a treated work-function metal layer; and
while maintaining the vacuum condition and after performing the fluorine-based treatment, depositing a TiAlC layer over the treated work-function metal layer.
20. The method of claim 19 , wherein x is between approximately 1 and approximately 6.