Trench-filling method and film-forming system

A method of filling a trench, comprising:

• heating a semiconductor substrate having a trench formed therein and an oxide film formed at least on the sidewall of the trench and supplying an aminosilane gas to the surface of the semiconductor substrate so as to form a seed layer on the semiconductor substrate;
• heating the semiconductor substrate having the seed layer formed thereon and supplying a monosilane gas to the surface of the seed layer so as to form a silicon film on the seed layer;
• filling the trench of the semiconductor substrate, which has the silicon film formed thereon, with a filling material that shrinks by burning;
• and
• burning the semiconductor substrate coated by the filling material filling the trench in an atmosphere containing water and/or a hydroxy group while changing the filling material into a silicon oxide and changing the silicon film and the seed layer into a silicon oxide;
• heating the semiconductor substrate having the seed layer formed thereon and supplying a higher order silane gas than monosilane to the surface of the seed layer between said forming the seed layer and said forming the silicon film.