Topographic selective deposition

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.

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.