Method for depositing a chlorine-free conformal SiN film
Described are methods of making silicon nitride (SiN) materials on substrates. Improved SiN films made by the methods are also included. One aspect relates to depositing chlorine (Cl)-free conformal SiN films. In some embodiments, the SiN films are Cl-free and carbon (C)-free. Another aspect relates to methods of tuning the stress and/or wet etch rate of conformal SiN films. Another aspect relates to low-temperature methods of depositing high quality conformal SiN films. In some embodiments, the methods involve using trisilylamine (TSA) as a silicon-containing precursor.
1. An apparatus for depositing a silicon nitride film on a semiconductor wafer, the apparatus comprising:
(a) a reaction chamber;
(b) a source of activation energy to form the silicon nitride film;
(c) a reactant inlet; and
(d) a controller comprising instructions for:
flowing a first nitrogen-containing reactant into the reaction chamber during a deposition cycle;
periodically flowing a silicon-containing reactant into the reaction chamber during the deposition cycle;
periodically igniting a plasma in the reaction chamber when the flow of the silicon-containing reactant has ceased and while the first nitrogen-containing reactant is present in the vapor phase in the reaction chamber; and
cycling the pressure in the reaction chamber such that it is higher during the flow of the silicon-containing reactant than when the flow of the silicon-containing reactant has ceased.
2. The apparatus of claim 1 , wherein the plasma is an RF plasma having a power between 0.15 W/cm 2 and 3 W/cm 2 .
3. The apparatus of claim 2 , wherein the plasma has a power between 0.15 W/cm 2 and 1 W/cm 2 .
4. The apparatus of claim 1 , wherein the plasma is an HF-only RF plasma.
5. The apparatus of claim 1 , wherein the first nitrogen-containing reactant is flowed into the reaction chamber under conditions such that it will adsorb onto the surface of a substrate in the reaction chamber.
6. The apparatus of claim 5 , wherein the silicon-containing reactant is flowed into the reaction chamber under conditions such that it will adsorb onto the surface of the substrate in the reaction chamber.
7. The apparatus of claim 1 , wherein the pressure in the reaction chamber is cycled between a first pressure and a second pressure, the first pressure being between about 5 and 50 Torr and the second pressure between about 1 and 5 Torr.
8. The apparatus of claim 1 , wherein the first nitrogen-containing reactant is flowed throughout the deposition cycle.
9. The apparatus of claim 1 , wherein the first nitrogen-containing reactant is flowed periodically during the deposition cycle.
10. The apparatus of claim 1 , wherein the controller further comprises instructions for:
periodically flowing a second nitrogen-containing reactant into the reaction chamber during the deposition cycle, the second nitrogen-containing reactant being different than the first nitrogen-containing reactant.
11. The apparatus of claim 10 , wherein the volumetric flow ratio of the first nitrogen-containing reactant to the second nitrogen-containing reactant is between about 1:1 and 10:1.
12. The apparatus of claim 10 , wherein the volumetric flow ratio of the first nitrogen-containing reactant to the second nitrogen-containing reactant is between about 1:10 and 1:1.
13. The apparatus of claim 1 , wherein the controller further comprises instructions for:
maintaining the substrate temperature at less than about 400° C.
14. The apparatus of claim 13 , wherein the substrate temperature is maintained at less than about 350° C.
15. The apparatus of claim 1 , wherein the silicon nitride material deposited during the deposition cycle has a stress between about −4 GPa and −2 GPa.
16. The apparatus of claim 1 , wherein the silicon nitride material deposited during the deposition cycle has a stress between about −2 GPa and 1 GPa.
17. The apparatus of claim 1 , wherein the silicon nitride material deposited during the deposition cycle conforms to the surface of the substrate including any raised or recessed features of the substrate.
18. The apparatus of claim 1 , wherein the source of activation energy is a plasma generator which is operated by the controller to periodically ignite the plasma in the reaction chamber.
19. The apparatus of claim 18 , wherein the plasma generator comprises induction coils and/or a microwave source.
20. A system comprising the apparatus of claim 1 and a stepper.