Coating process and equipment for reduced resist consumption
A coating system and method of coating semiconductor wafers is disclosed that is able to maintain a wet condition on the outer portion of the semiconductor wafer to provide ease of spreading for a photo-resist or anti-reflective coating (ARC) that is being dispensed. The system can include a plurality of nozzles on a movable arm. A first nozzle dispenses a pre-wet solvent onto the semiconductor wafer. A second nozzle then dispenses the photo-resist or ARC coating onto the semiconductor wafer. A third nozzle dispenses additional pre-wet solvent onto the outer edge of the semiconductor wafer as the photo-resist or ARC coating is being dispensed. The nozzles dispense solutions onto the semiconductor wafer as it rotates. The system produces semiconductor wafers with few coating defects and uses less photo-resist or ARC coating.
1. A method for coating a semiconductor wafer, comprising the steps of:
placing a semiconductor wafer on a platform that is rotatable;
dispensing a first solution from a first nozzle onto the semiconductor wafer;
rotating the semiconductor wafer at a first speed while the first solution is dispensed on the semiconductor wafer;
dispensing a second solution, different from the first solution, from a second nozzle onto the semiconductor wafer, the second solution being dispensed onto the semiconductor wafer while the first solution is still wet on the semiconductor wafer as it rotates at a second speed higher than the first speed; and
dispensing additional first solution from a third nozzle onto the semiconductor wafer while the semiconductor wafer continues to spin at a speed higher than the first speed, wherein the third nozzle is a shower-type nozzle.
2. The method of claim 1 , wherein the first solution is a pre-wet solvent.
3. The method of claim 2 , wherein the second solution is photo-resist coating.
4. The method of claim 2 , wherein the second solution is an anti-reflective coating.
5. The method of claim 1 , wherein the first speed is in a range about 500 to 1000 rpm.
6. The method of claim 1 , wherein the second speed is in a range about 3000 to 5000 rpm.
7. The method of claim 1 , wherein the semiconductor wafer is at least 300 mm in diameter.
8. The method of claim 1 , wherein the step of dispensing the additional first solution further comprises directing the solution toward an outer portion of the semiconductor wafer.
9. The method of claim 8 , wherein the outer portion of the semiconductor wafer is an annular region 50 mm or less in a radial direction of the semiconductor wafer.
10. The method of claim 8 , wherein the outer portion of the wafer is one-sixth of the diameter of the semiconductor wafer.
11. A method for coating a semiconductor wafer, comprising the steps of:
dispensing a pre-wet solvent from a first nozzle onto the semiconductor wafer;
rotating the semiconductor wafer at a first rate in a range of about 500 to 1000 rpm while the pre-wet solvent dispensed from the first nozzle is dispersed on the semiconductor wafer;
dispensing a photo-resist solution from a second nozzle onto the semiconductor wafer as it spins at a second rate in a range of about 3000 to 5000 rpm;
dispensing pre-wet solvent from a third nozzle onto the semiconductor wafer as it rotates at the second rate, wherein the solvent from the third nozzle is directed toward an outer portion of the semiconductor wafer, and wherein the third nozzle is a shower-type nozzle; and
stopping the third nozzle from dispensing the pre-wet solvent before the photo-resist solution spreads to the outer portion of the semiconductor wafer and while the semiconductor wafer continues to rotate at the second speed.
12. The method of claim 11 , wherein the semiconductor wafer is at least 300 mm in diameter.
13. The method of claim 11 , wherein the outer portion of the semiconductor wafer is an annular region 50 mm or less in a radial direction of the semiconductor wafer.