According to the invention there is provided a method of filling one or more gaps created during manufacturing of a feature on a substrate by providing a deposition method comprising; introducing a first reactant to the substrate with a first dose, thereby forming no more than about one monolayer by the first reactant; introducing a second reactant to the substrate with a second dose. The first reactant is introduced with a sub saturating first dose reaching only a top area of the surface of the one or more gaps and the second reactant is introduced with a saturating second dose reaching a bottom area of the surface of the one or more gaps. A third reactant may be provided to the substrate in the reaction chamber with a third dose, the third reactant reacting with at least one of the first and second reactant.

A plasma processing apparatus includes a chamber, a substrate support provided in the chamber, a gas supply that supplies a first processing gas and a second processing gas different from the first processing gas into the chamber, a plasma generator that generates a first plasma from the first processing gas and a second plasma from the second processing gas, and a controller. The controller executes a process including: (a) controlling the gas supply and the plasma generator so as to form a deposit on a first region of the substrate using the first plasma; and (b) controlling the gas supply and the plasma generator so as to etch a second region of the substrate using the second plasma.

A method for selectively etching silicon germanium with respect to silicon in a stack on a chuck in an etch chamber is provided. The chuck is maintained at a temperature below 15 C. The stack is exposed to an etch gas comprising a fluorine containing gas to selectively etch silicon germanium with respect to silicon.