Pulsing RF power in etch process to enhance tungsten gapfill performance
Methods and apparatuses for filling features with metal materials such as tungsten-containing materials in a substantially void-free manner are provided. In certain embodiments, the method involves depositing an initial layer of a metal such as a tungsten-containing material followed by removing a portion of the initial layer to form a remaining layer, which is differentially passivated along the depth of the high-aspect ratio feature. The portion may be removed by exposing the tungsten-containing material to a plasma generated from a fluorine-containing nitrogen-containing gas and pulsing and/or ramping the plasma during the exposure.
1. A method comprising:
providing a substrate having a feature partially filled with a metal to a process chamber having a radio frequency plasma source for generating a capacitively coupled or inductively coupled plasma;
exposing the partially filled feature to a fluorine- and nitrogen-based plasma generated by the radio frequency plasma source to remove a portion of the metal; and
pulsing the radio frequency plasma source for generating the capacitively coupled or inductively coupled plasma during the exposure.
2. The method of claim 1 , wherein the metal is tungsten.
3. The method of claim 1 , wherein the radio frequency plasma source is pulsed between an ON state and an OFF state, wherein plasma power during the OFF state is 0 W and the plasma power during the ON state is between about 50 W and about 3000 W.
4. The method of claim 1 , wherein the radio frequency plasma source is pulsed at a frequency between about 1 Hz and about 400 kHz.
5. The method of claim 1 , wherein the radio frequency plasma source is pulsed using a duty cycle between about 10% and about 90%.
6. The method of claim 1 , wherein the radio frequency plasma source is pulsed between an ON state and an OFF state, and wherein the plasma is in the ON state for a duration between about 100 milliseconds and about 10 seconds in each pulse.
7. The method of claim 1 , wherein exposing the partially filled feature to the fluorine- and nitrogen-based plasma comprises flowing a fluorine- and nitrogen-containing gas and igniting the fluorine- and nitrogen-based plasma using the radio frequency plasma source.
8. The method of claim 7 , wherein fluorine- and nitrogen-containing gas flow is pulsed.
9. The method of claim 8 , wherein the fluorine- and nitrogen-containing gas flow is pulsed using a duty cycle between about 30% and about 70%.
10. The method of claim 8 , wherein the fluorine- and nitrogen-containing gas flow is pulsed for a pulse duration between about 0.5 seconds and about 3 seconds.
11. The method of claim 8 , wherein the fluorine- and nitrogen-containing gas is nitrogen trifluoride.
12. The method of claim 1 , further comprising, after removing the portion of the metal, exposing the substrate to a metal-containing precursor to deposit additional metal in the feature.
13. A method comprising:
providing a substrate having a feature partially filled with tungsten to a process chamber having a radio frequency plasma source for generating a capacitively coupled or inductively coupled plasma;
introducing a fluorine- and nitrogen-containing gas to the process chamber;
pulsing flow of the fluorine- and nitrogen-containing gas; and
igniting an inductively coupled or capacitively coupled plasma in the process chamber to generate a fluorine- and nitrogen-based plasma to etch a portion of the tungsten; and
pulsing the radio frequency plasma source for generating the capacitively coupled or inductively coupled plasma during the igniting of the plasma.
14. The method of claim 13 , wherein fluorine- and nitrogen-containing gas flow is pulsed using a duty cycle between about 30% and about 70%.
15. The method of claim 13 , wherein fluorine- and nitrogen-containing gas flow is pulsed for a duration between about 0.5 seconds and about 3 seconds.
16. The method of claim 13 , wherein the fluorine- and nitrogen-containing gas is nitrogen trifluoride.
17. The method of claim 13 , wherein the plasma is pulsed between an ON state and an OFF state, wherein plasma power during the OFF state is 0 W and the plasma power during the ON state is between about 50 W and about 3000 W.
18. The method of claim 13 , wherein the plasma is pulsed at a frequency between about 1 Hz and about 400 kHz.