Apparatus and method for coating photoresist

1. A method for coating a photoresist on a substrate, the method comprising:

dispensing a photoresist on the substrate at a discharge unit of a nozzle while the nozzle is moved from one end portion of the substrate to the other end portion thereof;

while moving the nozzle to dispense photoresist, diagonally radiating a first light from a light emitting unit disposed at a lower portion of a foreign substance barrier toward the substrate, the first light being reflected by the substrate and received by a light receiving unit without being affected by a foreign substance;

determining a reference strength of a reflected portion of the first light received by the light receiving unit;

diagonally radiating a second light from the light emitting unit toward the substrate, the second light being reflected by the substrate and received by the light receiving unit;

determining whether the foreign substance exists on the substrate based on a comparison between the reference strength of the reflected portion of the first light and a strength of a reflected portion of the second light,

wherein the foreign substance barrier is inclined by 1° to 85° from an upper surface of the substrate,

wherein an interval between the discharge unit and the foreign substance barrier is 10 to 300 μm, and

wherein the foreign substance barrier is disposed on a bottom surface of the nozzle.

2. The method according to claim 1 , further comprising the steps of:

controlling the movement of the nozzle and the supply of the photoresist on the substrate depending on whether the foreign substance exists on the substrate.

3. The method according to claim 2 , wherein the movement of the nozzle and the supply of the photoresist on the substrate are stopped when the foreign substance exists on the substrate.

4. The method of claim 1 , wherein the light is radiated from the light emitting unit by affixing a laser to the nozzle.

5. The method of claim 4 , wherein the radiated light is diagonally reflected by the substrate or foreign substance.

6. The method of claim 1 , wherein the light receiving unit is disposed on a top surface of the nozzle opposite to the bottom surface of the nozzle and protrudes beyond the light emitting unit in a direction of moving.

7. The method of claim 1 , wherein the interval between the discharge unit and the foreign substance barrier is adjustable according to manufacturing requirements.

8. The method of claim 1 , wherein the light receiving unit is in the form of a plate extending forwardly from the light emitting unit.

9. The method of claim 1 , wherein the light receiving unit is parallel to the substrate.