Chemical vapor deposition of TiN films in a batch reactor
Titanium nitride (TiN) films are formed in a batch reactor using titanium chloride (TiCl 4 ) and ammonia (NH 3 ) as precursors. The TiCl 4 is flowed into the reactor in temporally separated pulses. The NH 3 can also be flowed into the reactor in temporally spaced pulses which alternate with the TiCl 4 pulses, or the NH 3 can be flowed continuously into the reactor while the TiCl 4 is introduced in pulses. The resulting TiN films exhibit low resistivity and good uniformity.
1. A method of forming a titanium nitride film by chemical vapor deposition, comprising:
providing a vertical furnace having a reaction chamber, the reaction chamber configured to accommodate 25 or more substrates;
providing a plurality of substrates in the reaction, chamber;
chemical vapor depositing the titanium nitride film on the plurality of substrates by performing a plurality of chemical vapor deposition cycles, each cycle performed at a deposition temperature of less than about 500° C. and each cycle comprising:
exposing the plurality of substrates to a titanium precursor by flowing the titanium precursor into the reaction chamber;
simultaneously flowing a nitrogen precursor into the reaction chamber while exposing the plurality of substrates to the titanium precursor;
stopping the flow of the titanium precursor; and
subsequently exposing the plurality of substrates to the nitrogen precursor by flowing the nitrogen precursor into the reaction chamber at an elevated flow rate, wherein the elevated flow rate is higher than a flow rate of the nitrogen precursor during the exposing of the plurality of substrates to the titanium precursor, wherein the titanium nitride film formed by performing the plurality of chemical vapor deposition cycles has a resistivity that varies by less than about 5 μOhm-cm from substrate to substrate within the plurality of substrates.
2. The method of claim 1 , wherein the substrates are 200 mm wafers.
3. The method of claim 1 , wherein the substrates are 300 mm wafers.
4. The method of claim 1 , wherein flowing the titanium precursor comprises depositing more than one monolayer of titanium nitride over each of the substrates during each of the plurality of chemical vapor deposition cycles.
5. The method of claim 4 , wherein flowing the nitrogen precursor comprises continuously flowing the nitrogen precursor into the reaction chamber between and during each of the plurality of chemical vapor deposition cycles.
6. The method of claim 1 , wherein flowing the nitrogen precursor comprises introducing the nitrogen precursor from a plurality of vertically distributed points distributed substantially along a vertical axis of the reaction chamber.
7. The method of claim 6 , wherein the plurality of vertically distributed points are holes of a gas injector.
8. The method of claim 6 , wherein flowing the titanium precursor comprises introducing the titanium precursor proximate to only one end of the reaction chamber and flowing the titanium precursor toward an other end of the reaction chamber.
9. The method of claim 1 , wherein the titanium precursor and the nitrogen precursor are non-radical species.
10. The method of claim 1 , wherein the titanium precursor is titanium tetrachloride.
11. The method of claim 10 , wherein flowing the titanium precursor comprises flowing an inert gas through a bubbler comprising the titanium tetrachloride.
12. The method of claim 10 , wherein flowing the titanium precursor comprises vaporizing the titanium tetrachloride in a liquid vaporizer.
13. The method of claim 10 , wherein the nitrogen precursor is ammonia.
14. The method of claim 1 , wherein flowing the titanium precursor and flowing the nitrogen precursor comprise introducing the titanium precursor and the nitrogen precursor through an inlet proximate one vertical end of the reaction chamber and exhausting the titanium precursor and the nitrogen out of an opposing vertical end of the reaction chamber.
15. The method of claim 1 , wherein the reaction chamber is configured to accommodate 50 or more substrates.
16. The method of claim 15 , wherein the reaction chamber is configured to accommodate 100 or more substrates.
17. The method of claim 1 , wherein each of the plurality of chemical vapor deposition cycles comprises purging the reaction chamber with an inert gas after exposing the plurality of substrates to the titanium precursor.
18. The method of claim 17 , wherein purging the reaction chamber with inert gas comprises flowing the nitrogen precursor into the reaction chamber with the inert gas.
19. The method of claim 1 , wherein, in each chemical vapor deposition cycle, exposing the plurality of substrates to the titanium precursor occurs for about 30 seconds or less.
20. The method of claim 1 , wherein chemical vapor depositing the titanium nitride film forms the titanium nitride film having a resistivity of about 220 μOhm·cm or less.