Film forming method and film forming apparatus

1. A film forming method, the method comprising:

forming a thin unit film on a target substrate by supplying processing gases sequentially and intermittently into a processing space, wherein the target substrate is placed in the processing space, in a processing chamber of a film forming apparatus while purging the processing gases with a purge gas continuously supplied into the processing space; and

repeating said forming the thin unit film to form a film having a predetermined thickness on the target substrate,

wherein the film forming apparatus includes an exhaust unit having a trap for trapping byproducts produced by a reaction between the processing gases,

wherein a pressure in the processing chamber is set such that the trap does not limit a substitution rate at which the processing gases are substituted with the purge gas,

wherein a flow rate of the purge gas supplied into the processing space is set such that the film is formed in an ALD (atomic layer deposition) mode at the pressure in the processing chamber,

wherein the pressure in the processing chamber is in a range between 3 Torr and 7 Torr, wherein the flow rate of the purge gas is 5,000 mL/min or higher for a volume of the processing space in a range between 650 mL and 850 mL, and

wherein the flow rate of the purge gas is 8,500 mL/min or higher for a volume of the processing space in a range between 1,300 mL and 1,700 mL.

2. A film forming method, the method comprising:

forming a thin unit film on a target substrate by supplying processing gases sequentially and intermittently into a processing space, where the target substrate is placed, in a processing chamber of a film forming apparatus while purging the processing gases with a purge gas continuously supplied into the processing space; and

repeating said forming the thin unit film to form a film having a predetermined thickness on the target substrate,

wherein the film forming apparatus comprises an exhaust unit having a trap for trapping byproducts produced by a reaction between the processing gases,

wherein a processing pressure in the processing space is set such that the trap does not limit a substitution rate at which the processing gases are substituted with the purge gas, and

wherein a flow rate of the purge gas is set such that the film is formed in an ALD (atomic layer deposition) mode at the processing pressure.

3. The method of claim 1 , wherein the film forming apparatus comprises a mounting table on which the target substrate is placed in the processing chamber and a cap member arranged above the mounting table and including a depressed portion, and the processing space is defined by the mounting table and the depressed portion of the cap member.

4. The method of claim 2 , wherein the film forming apparatus comprises a mounting table on which the target substrate is placed in the processing chamber and a cap member arranged above the mounting table and including a depressed portion, and the processing space is defined by the mounting table and the depressed portion of the cap member.

5. The method of claim 1 , wherein the processing gases includes TiCl 4 gas and NH 3 gas, and the film includes a TiN film.

6. The method of claim 2 , wherein the processing gases includes TiCl 4 gas and NH 3 gas, and the film includes a TiN film.

7. The method of claim 1 , wherein the flow rate of the purge gas supplied into the processing space is constant during said forming the thin unit film.

8. The method of claim 2 , wherein the flow rate of the purge gas supplied into the processing space is constant during said forming the thin unit film.