Method and apparatus for filling a gap

A method of filling one or more gaps on a substrate, the method comprising the steps of:

• providing the substrate in a reaction chamber;
• introducing a first reactant to the substrate with a first dose to form a layer using the first reactant in a first area of the gap;
• introducing a second reactant to the substrate with a second dose to form a layer using the second reactant in a second area of the gap, wherein the first and the second areas overlap in an overlap area and leave an area where the first and the second areas do not overlap;
• and,
• introducing a third reactant to the substrate with a third dose, the third reactant reacting with the first or second reactant remaining on the area where the first and the second areas do not overlap,
• wherein one or more of the first reactant and the third reactant are plasma activated, and
• wherein the method further comprises one or more of:
• in between introducing the first and the second reactant, introducing the first reactant again to the substrate, and
• in between introducing the second and the third reactant, introducing the second reactant again to the substrate.

A semiconductor processing apparatus comprising:

• one or more reaction chambers for accommodating a substrate provided with gaps created during manufacturing of a feature on the substrate;
• a first source for a first reactant in gas communication via a first valve with one of the reaction chambers;
• and,
• a second source for a second reactant in gas communication via a second valve with one of the reaction chambers, wherein the apparatus comprises:
• a third source for a third reactant in gas communication via a third valve with one of the reaction chambers;
• and
• a controller operably connected to the first, second and third gas valves and configured and programmed to control:
• introducing a first reactant to the substrate with a first dose on a first area of the surface of the one or more gaps;
• introducing a second reactant to the substrate with a second dose on a second area of the surface of the one or more gaps,
• wherein the first and the second areas overlap in an overlap area and leave an area where the first and the second areas do not overlap,
• wherein one of the first reactant and the second reactant comprises silicon;
• and,
• introducing a third reactant to the substrate with a third dose, the third reactant reacting with the first or second reactant remaining on the area where the first and the second areas do not overlap.