Apparatus for growing thin films

An apparatus for growing thin films onto the surface of a substrate by exposing the substrate to alternately repeated surface reactions of vapor-phase reactants, the apparatus comprising:

• a reaction chamber including a reaction space, an inlet connected to said reaction space for supplying a plurality of reactant pulses into said reaction space, and an outlet connected to said reaction space for discharging excess reactants and gaseous reaction products from said reaction space;
• a first substrate disposed within said reaction space, said first substrate comprising a first surface configured for growing thin films;
• a second surface which is also disposed within said reaction space, said second surface being spaced from and facing said first surface so as to form at least in part a passage through which said reactant pulses can flow from said inlet to said outlet, said passage having an inlet portion and an outlet portion, said inlet portion located closer said inlet than said outlet portion and said outlet portion located closer to said outlet than said inlet portion,
• wherein a distance between said first surface and said second surface at said inlet portion is smaller than a distance between said first surface and said second surface at said outlet portion.