Topographic selective deposition
A method of processing a substrate that includes: flowing a gas including a fluorocarbon to a plasma processing chamber; sustaining a plasma generated from the gas; depositing a carbonaceous layer over the substrate by exposing the substrate to the plasma, the substrate having a recess having an aspect ratio between 10:1 and 100:1, the depositing including a pulsed plasma process including: during a first time duration, setting a source power (SP) at a first SP level and a bias power (BP) at a first BP level, where the plasma includes fluorocarbon ions polymerizing on a bottom surface to form the carbonaceous layer, and during a second time duration, setting the SP at a second SP level higher than the first SP level and the BP at a second BP level lower than the first BP level, where the plasma includes fluorine radicals trimming the carbonaceous layer.
1. A method of processing a substrate, the method comprising:
flowing a gas comprising a fluorocarbon to a plasma processing chamber;
sustaining a plasma generated from the gas in the plasma processing chamber; and
depositing a carbonaceous layer over the substrate by exposing the substrate to the plasma, the substrate comprising top and bottom surfaces, the bottom surface being at a bottom of a recess of the substrate, the recess having an aspect ratio between 10:1 and 100:1, the carbonaceous layer being deposited on the bottom surface, the depositing comprising a pulsed plasma process comprising a plurality of pulse cycles, each pulse cycle of the pulsed plasma process comprising:
during a first time duration, setting a source power (SP) at a first SP level and a bias power (BP) at a first BP level, wherein the plasma during the first time duration comprises fluorocarbon ions, the fluorocarbon ions polymerizing on the bottom surface to form the carbonaceous layer, and
during a second time duration, setting the SP at a second SP level higher than the first SP level and the BP at a second BP level lower than the first BP level, wherein the plasma during the second time duration comprises fluorine radicals, the fluorine radicals trimming the carbonaceous layer.
2. The method of claim 1 , wherein the pulsed plasma process further comprises maintaining a chamber pressure of the plasma processing chamber between 50 mTorr and 100 mTorr.
3. The method of claim 1 , wherein the plurality of pulse cycles is repeated at a frequency between 100 Hz and 1 kHz.
4. The method of claim 1 , wherein the first SP level is between 100 W and 400 W and the second SP level is between 350 W and 650 W.
5. The method of claim 1 , wherein the first BP level is between 50 W and 100 W and the second BP level is between 10 W and 40 W.
6. The method of claim 1 , wherein one pulse cycle of the pulsed plasma process further comprises, between the first and second time durations, turning off the SP and BP for a third time duration.
7. The method of claim 1 , wherein one pulse cycle of the pulsed plasma process further comprises, after the second time duration, turning off the SP and BP for a fourth time duration.
8. The method of claim 1 , wherein the carbonaceous layer is deposited on both the top and bottom surfaces during the first time duration.
9. The method of claim 8 , wherein the carbonaceous layer is deposited on sidewalls of the recess at a deposition rate slower than those on the top and bottom surfaces.
10. The method of claim 9 , wherein trimming the carbonaceous layer removes the carbonaceous layer from the sidewalls.
11. A method of processing a substrate, the method comprising:
flowing a gas comprising a fluorocarbon to a plasma processing chamber;
sustaining a plasma generated from the gas in the plasma processing chamber;
depositing a carbonaceous layer over the substrate by exposing the substrate to the plasma, the substrate comprising top and bottom surfaces, the bottom surface being at a bottom of a recess of the substrate, the recess having an aspect ratio between 10:1 and 100:1, the carbonaceous layer being deposited on the bottom surface, the depositing comprising performing a pulsed plasma process with a pulse pattern, the pulse pattern comprising:
during a plasma-on phase, setting a source power (SP) at a first SP level, and
during an afterglow phase, setting the SP at zero relative to ground potential and a bias power (BP) at a first BP level,
wherein the first SP level is selected to produce fluorocarbon ions and radical species,
wherein the first BP level is selected to
increase a thickness of a plasma sheath of the plasma during the afterglow phase relative to that during the plasma-on phase, and
cause collisions and charge exchange between the fluorocarbon ions and radical species to form fast neutrals species from the fluorocarbon ions, the fast neutrals species polymerizing on the bottom surface to form the carbonaceous layer.
12. The method of claim 11 , further comprising, during the plasma-on phase, setting the BP at zero relative to the ground potential.
13. The method of claim 11 , wherein the pulsed plasma process further comprises maintaining a chamber pressure of the plasma processing chamber between 1 mTorr and 50 mTorr.
14. The method of claim 11 , wherein the pulse pattern has a frequency between 100 Hz and 1 kHz.
15. The method of claim 11 , wherein the first BP level is between 10 W and 100 W.
16. The method of claim 11 , wherein the pulse pattern further comprises, after the afterglow phase, turning off the SP and BP for a third time duration.
17. A method of processing a substrate, the method comprising:
flowing a gas comprising a fluorocarbon to a plasma processing chamber;
sustaining a plasma generated from the gas in the plasma processing chamber; and
etching the substrate to form a recess having an aspect ratio between 10:1 and 100:1 using a patterned etch mask disposed over the substrate, the etching comprising exposing the substrate to the plasma, the exposing comprising cyclically repeating an etch phase and a passivation phase,
wherein, during the passivation phase, a carbonaceous layer is deposited over a top surface of the patterned etch mask, and
wherein the passivation phase comprises
during a first time duration, setting a source power (SP) at a first SP level and a bias power (BP) at a first BP level, the first SP level being higher than the first BP level, and
during a second time duration, setting the SP at a second SP level lower than the first SP level and the BP at a second BP level higher than the first BP level, the second BP level being higher than the second SP level.
18. The method of claim 17 , wherein the first BP level or the second SP level is zero relative to ground potential, and wherein the second BP level is selected to generate fluorocarbon fast neutral species from fluorocarbon ions, the fluorocarbon fast neutral species polymerizing on the top surface of the patterned etch mask to form the carbonaceous layer.
19. The method of claim 17 , wherein the first SP level and the first BP level are selected to form fluorine radicals in the plasma, the fluorine radicals trimming the carbonaceous layer.
20. The method of claim 17 , wherein the second SP level and the second BP level are selected to form fluorocarbon ions in the plasma, the fluorocarbon ions polymerizing on the top surface of the patterned etch mask to form the carbonaceous layer.