Method of manufacturing semiconductor device

1. A method for manufacturing a semiconductor device comprising the steps of:

preparing a substrate with wiring on a lower insulating layer, said wiring having a plurality of separating portions;

forming first and second water marks on the lower insulating layer respectively located in the separating portions and on upper surfaces of the wiring;

transforming the first and second water marks into first and second air bubbles, respectively;

depositing a first insulating layer of dielectric constant lower than about 3.5 on a whole surface of the substrate, and also, forming first and second air gaps by growing said first and second air bubbles between and on the wirings, respectively;

removing the upper portion of the first insulating layer to open the second air gap; and

depositing a second insulating layer of dielectric constant lower than about 3.5 on the first insulating layer to fill the opened second air gap.

2. The method of claim 1 , wherein the step for forming the water marks includes the steps of:

cleaning the substrate with the wiring with HCl solution;

drying the cleaned substrate by a spin dry method; and

exposing the dried substrate to atmospheric air.

3. The method of claim 2 , wherein the spin dry is performed at a gradually decreasing speed of equal to or less than 1,000 rpm.

4. The method of claim 2 , wherein the step of exposing the dried substrate to atmospheric air continues more than about 4 hours.

5. The method of claim 3 , wherein the step of exposing the dried substrate to atmospheric air continues more than about 4 hours.

6. The method of claim 1 , wherein the air bubbles are formed by annealing the substrate under inert gas environment and at a temperature ranging from 300 to 500 ° C.

7. The method of claim 6 , the inert gas is one selected from a group consisting of Ar, He, Xe, Kr and Ne.

8. The method of claim 1 , wherein the first insulating layer is formed by PECVD (Plasma Enhanced Chemical Vapor Deposition) of FSG (Fluorinated Silica Glass) film or SiOC film.

9. The method of claim 1 , wherein the step of forming the first insulating layer includes depositing a material having a dielectric constant in an inclusive range of 2 through 3.

10. The method of claim 1 , wherein the second insulating layer is formed by SOG (Spin On Glass) deposition of a fluorine-doped polyimide film, a nano-porous Si film or an aromatic hydrocarbon poly ether film and annealing.

11. The method of claim 1 , wherein in the step of depositing the second insulating layer includes depositing a material having a dielectric constant in an inclusive range of 2 through 3.

12. A method for manufacturing a semiconductor device comprising the steps for:

preparing a substrate with wiring on a lower insulating layer, said wiring having a plurality of separating portions;

forming first and second water marks on the lower insulating layer respectively located in the separating portions and on upper surfaces of the wiring;

transforming the first and second water marks into first and second air bubbles, respectively;

depositing a first insulating layer of dielectric constant lower than about 3.5 on a whole surface of the substrate, and also, forming first and second air gaps by growing said first and second air bubbles between and on the wirings, respectively;

removing the upper portion of the first insulating layer to open the second air gap; and

depositing a second insulating layer of dielectric constant lower than about 3.5 on the first insulating layer to fill the opened second air gap.