Patent ID: 7713874

Claim:
An atomic layer deposition process for forming a thin film on a substrate in a reaction space, comprising in sequence: a) depositing a layer of a first thickness by: contacting the substrate with a vapor phase pulse of a metal source chemical; removing excess metal source chemical from the reaction space; contacting the substrate with a vapor phase pulse of one or more plasma-excited reducing species during a first period of time; and removing excess plasma-excited reducing species and reaction by-products from the reaction space; b) repeating step a) for a first number of cycles until the layer of the first thickness is formed; c) contacting the substrate with a second vapor phase pulse of one or more plasma-excited reducing species during a second period of time, the total second period being not less than about twice as long as the total first period of time that the substrate is contacted with a plasma-excited reducing species in step a); and d) repeating steps a) through c) for a second number of cycles until a film of a second thickness is formed over the substrate.