Smooth silicon-containing films

A method for forming a stack of films for a three-dimensional memory device, the method comprising depositing a plurality of films, wherein the plurality of films comprises films having a first composition and films having a second composition, different from the first composition, wherein the films having the first and second composition alternate within the stack, and wherein at least one film in the deposited stack is a silicon-containing film deposited on a substrate in a plasma-enhanced chemical vapor deposition apparatus, by a method comprising:

• supplying a silicon-containing reactant to the plasma-enhanced chemical vapor deposition apparatus, wherein the silicon-containing reactant comprises one or more reactants selected from the group consisting of silane, disilane, a halogen-substituted silane, and an alkyl-substituted silane;
• supplying a co-reactant to the plasma-enhanced chemical vapor deposition apparatus, wherein the co-reactant comprises one or more co-reactants selected from the group consisting of NH3, N2O, CO, and CO2;
• supplying a capacitively-coupled plasma to a process station of the plasma-enhanced chemical vapor deposition apparatus, the plasma including silicon radicals generated from the silicon-containing reactant and co-reactant radicals generated from the co-reactant;
• and
• depositing the silicon-containing film on the substrate at a deposition rate of less than 10 Å/second, the silicon-containing film being deposited under process conditions that produce a film having a refractive index of between 1.4 and 2.1, and an absolute roughness of less than 4.5 Å as measured on a silicon substrate for up to 3000 Å of deposited film, wherein the absolute roughness does not substantially increase with increasing deposited thickness for up to 3000 Å of deposited film, wherein said process conditions comprise:
• supplying the co-reactant in an amount that is at least 150 times the amount of the silicon-containing reactant;
• forming plasma that comprises high frequency (HF) plasma generated with a power density of at least 0.35 W/square inch, wherein the formed plasma has an ion density of less than 2×1010 ions/cm3;
• depositing the silicon-containing film at a pressure of about 8 torr or less and at a temperature of between 300-600° C.