METHOD OF FABRICATING A SEMICONDUCTOR DEVICE WITH A POROUS DIELECTRIC FILM
In the fabrication of a semiconductor device, an SiO 2 GeO 2 film is formed on a substrate, then washed with water to dissolve the GeO 2 , leaving a porous SiO 2 film. The SiO 2 GeO 2 film may be deposited directly on the substrate, or an SiGe film may be deposited on the substrate and then oxidized to form the SiO 2 GeO 2 film. The porous SiO 2 film has an easily controllable dielectric constant and can be advantageously used as an interlayer dielectric film.
1 . A method of fabricating a semiconductor device, comprising:
forming an SiO 2 GeO 2 film on a substrate; and
washing the SiO 2 GeO 2 film in water, thereby dissolving the GeO 2 included in the SiO 2 GeO 2 film and leaving a porous SiO 2 film.
2 . The method of claim 1 , wherein the SiO 2 GeO 2 film is crystalline.
3 . The method of claim 1 , wherein washing the SiO 2 GeO 2 film in water comprises washing the SiO 2 GeO 2 film in an aqueous solution of hydrogen peroxide.
4 . The method of claim 1 , wherein SiO 2 and GeO 2 are present in substantially equal proportions in the SiO 2 GeO 2 film.
5 . The method of claim 1 , wherein forming the SiO 2 GeO 2 film further comprises:
depositing an SiGe film on the substrate from a mixture of a gas containing silicon and a gas containing germanium; and
oxidizing the SiGe film.
6 . The method of claim 5 , wherein the gas containing silicon is SiH 4 .
7 . The method of claim 5 , wherein the gas containing germanium is GeH 4 .
8 . The method of claim 5 , wherein the gas containing germanium is GeF 4 .
9 . The method of claim 1 , wherein forming the SiO 2 GeO 2 film comprises depositing an SiO 2 GeO 2 film from a mixture of a gas containing silicon, a gas containing germanium, and a molecular oxygen gas.
10 . The method of claim 9 , wherein the gas containing silicon is SiH 4 .
11 . The method of claim 9 , wherein the gas containing germanium is GeH 4 .
12 . The method of claim 9 , wherein the gas containing germanium is GeF 4 .
13 . The method of claim 9 , further comprising annealing the SiO 2 GeO 2 film before washing the SiO 2 GeO 2 film.
14 . The method of claim 13 , wherein annealing the SiO 2 GeO 2 film further comprises heating the SiO 2 GeO 2 film in an atmosphere including at least 20% oxygen.
15 . The method of claim 1 , further comprising forming an electrically conductive wire in the porous SiO 2 film.
16 . The method of claim 15 , wherein forming the electrically conductive wire further comprises:
forming a trench in a surface of the porous SiO 2 film;
depositing a barrier layer on the porous SiO 2 film, the barrier layer including an inner barrier layer covering wall and floor surfaces of the trench and an outer barrier layer covering the surface of the porous SiO 2 film outside the trench;
depositing a layer of interconnect material, the layer of interconnect material including an inner layer of interconnect material filling the trench up to a level even with the surface of the porous SiO 2 film outside the trench and an outer layer of interconnect material covering the inner layer of interconnect material and the surface of the porous SiO 2 film outside the trench; and
removing the outer layer of interconnect material and the outer barrier layer, leaving the inner layer of interconnect material to form the electrically conductive wire.
17 . The method of claim 16 , further comprising annealing the porous SiO 2 film before forming the electrically conductive wire.
18 . The method of claim 17 , wherein annealing the porous SiO 2 film further comprises heating the porous SiO 2 film in an atmosphere including at least 20% oxygen.