Method and apparatus for forming layer, metal oxide transistor and fabrication method thereof

1. A layer forming method comprising:

a source gas dosing/pressurizing step including a first sub-dosing/pressurizing step of dosing a source gas into a chamber having a substrate loaded therein in a state in which an outlet of the chamber is closed, thereby increasing pressure in the chamber and adsorbing the source gas onto the substrate, a sub-purging step of purging the chamber after the first sub-dosing/pressurizing step, and a second sub-dosing/pressurizing step of dosing the source gas into the chamber in a state in which the outlet of the chamber is closed, thereby increasing pressure in the chamber and adsorbing the source gas onto the substrate;

a first main purging step of purging the chamber, after the source gas dosing/pressurizing step;

a reactive gas dosing step of dosing a reactive gas into the chamber, after the first main purging step; and

a second main purging step of purging the chamber, after the reactive gas dosing step.

2. The layer forming method of claim 1 , wherein the source gas dosing/pressurizing step further comprises, between the sub-dosing/pressurizing step and the sub-purging step, a step of maintaining the chamber pressure that has been increased by the sub-dosing/pressurizing step.

3. The layer forming method of claim 1 , wherein the reactive gas dosing step further comprises the steps of:

increasing the pressure in the chamber to a predetermined pressure by dosing the reactive gas; and

maintaining the predetermined pressure by closing the inlet of the chamber.

4. The layer forming method of claim 1 , wherein the reactive gas dosing step comprises at least two sub-dosing/pressurizing steps and a sub-purging step between the at least two sub-dosing/pressurizing steps.

5. The layer forming method of claim 4 , wherein the reactive gas dosing step further comprises, between the sub-dosing/pressurizing step and the sub-purging step, a step of maintaining the chamber pressure that has been increased by the sub-dosing/pressurizing step.

6. The layer forming method of claim 1 , wherein the source gas comprises a metal precursor for forming a metal oxide layer by deposition.

7. The layer forming method of claim 6 , wherein the metal oxide layer, formed by the source gas dosing/pressurizing step, the first main purging step, the reactive gas dosing step and the second purging step, has a surface roughness (RMS) lower than 4.4 Å.

8. The layer forming method of claim 6 , wherein the metal oxide layer, formed by the source gas dosing/pressurizing step, the first main purging step, the reactive gas dosing step and the second purging step, comprises a plurality of crystalline regions, and an amorphous region surrounding the crystalline regions.

9. The layer forming method of claim 8 , wherein each of the crystalline regions has a nanometer size.

10. A method of fabricating a metal oxide transistor, comprising the steps of:

preparing a substrate; and

forming an active layer including a metal oxide layer on one side of the substrate,

wherein the step of forming the active layer comprises:

a source gas dosing/pressurizing step including a first sub-dosing/pressurizing step of dosing a source gas for metal oxide deposition into a chamber having the substrate loaded therein in a state in which an outlet of the chamber is closed, thereby increasing pressure in the chamber and adsorbing the source gas onto the substrate in the closed chamber, a sub-purging step of purging the chamber after the first sub-dosing/pressurizing step, and a second sub-dosing/pressurizing step of dosing the source gas into the chamber in a state in which the outlet of the chamber is closed, thereby increasing pressure in the chamber and adsorbing the source gas onto the substrate in the closed chamber;

a first main purging step of purging the chamber, after the source gas dosing/pressurizing step;

a reactive gas dosing step of dosing a reactive gas into the chamber, thereby depositing a metal oxide layer on the substrate, after the first main purging step; and

a second main purging step of purging the chamber, after the reactive gas dosing step.

11. The method of claim 10 , wherein the source gas dosing/pressurizing step, the first main purging step, the reactive gas dosing step and the second main purging step constitute a unit process, and electrical properties of the active layer is variable depending on the number of repetitions of the unit process.