Claims
- 1. A method of coating a resist solution on to a substrate using at least a first nozzle that is moveable from a home position where the at least a first nozzle is not over the substrate to a resist solution coating position in which the at least a first nozzle is over the substrate, comprising the steps of:(a) holding the substrate substantially horizontally; (b) determining a reference particle diameter and an allowable maximum limit number relative to particles to be counted in the resist solution to be coated; (c) controlling a flow rate of the resist solution to be coated through a supply passage in communication with the at least a first nozzle and forming a sample of predetermined size outside of said supply passage based on the controlled flow rate of the resist solution to be coated before said resist solution is used to coat said substrate; (d) irradiating the sample with light and detecting scattered light components indicative of particles having different particle diameters being present in the sample to obtain particle counts according to the different particle diameters and obtaining a count of particles in the sample having particle diameters greater than the reference particle diameter by discarding any particle counts that correspond to particles in the sample having particle diameters smaller than the reference particle diameter; (e) setting the at least a first nozzle to the resist coating position and supplying the at least a first nozzle with the resist solution corresponding to the resist solution forming the sample and discharging the supplied resist solution from the at least a first nozzle on to the substrate when the count of particles in the sample having particle diameters greater than the reference particle diameter is less than said allowable maximum limit number; and (f) spreading the discharged resist solution on to the substrate to thereby coat the substrate.
- 2. The method according to claim 1, further comprising generating an alarm when the count of particles having particle diameters greater than the reference particle diameter exceeds the allowable maximum limit number of particles.
- 3. The method according to claim 2, further comprising suspending further operation when said alarm is generated.
- 4. The method according to claim 2, further comprising setting the at least a first nozzle to the home position when the alarm is generated.
- 5. The method according to claim 2, wherein when the alarm is generated, setting the at least a first nozzle at the home position and moving another nozzle from the home position with the steps (c)-(f) being then performed relative to said another nozzle which has a different supply passage supplied with a different resist solution to be coated.
- 6. The method according to claim 1, further comprising selecting any one of four nozzles having respective different supply passages that are respectively supplied with a different resist solution as said at least a first nozzle.
- 7. The method according to claim 1, wherein step (d) is performed at regular intervals of time or each time after a particular event occurs.
- 8. The method according to claim 1, wherein the sample of step (c) is obtained by discharging the resist solution to be sampled from the at least a first nozzle at the home position.
- 9. The method according to claim 1, wherein step (e) is carried out after prior steps (c) and (d) are repeated a plurality of times.
- 10. The method according to claim 1, wherein the reference particle diameter is determined to be 0.25 μm.
- 11. A method of coating a resist solution on to a substrate using at least a first nozzle that is moveable from a home position where the at least a first nozzle is not over the substrate to a resist solution coating position in which the at least a first nozzle is over the substrate, comprising the steps of:(a) holding the substrate substantially horizontally; (b) determining a reference particle diameter and an allowable maximum limit number relative to particles to be counted in the resist solution to be coated; (c) controlling a flow rate of the resist solution to be coated through a supply passage in communication with the at least a first nozzle to discharge a predetermined amount of the resist solution to be coated from the at least one first nozzle to a receptacle to form a receptacle sample of the resist solution to be coated before the at least one nozzle is moved to the resist coating position; (d) irradiating the receptacle sample with light and detecting scattered light components indicative of particles having different particle diameters being present in the receptacle sample to obtain particle counts according to the different particle diameters and obtaining a count of particles in the receptacle sample having particle diameters greater than the reference particle diameter by discarding any particle counts that correspond to particles in the receptacle sample having particle diameters smaller than the reference particle diameter; (e) moving the at least a first nozzle to the resist coating position and supplying the at least a first nozzle with the resist solution corresponding to the receptacle sample through the supply passage to discharge the supplied resist solution from the at least a first nozzle on to the substrate when the count of particles in the receptacle sample having particle diameters greater than the reference particle diameter is less than said allowed maximum limit number; and (f) spreading the discharged resist solution on to the substrate to thereby coat the substrate.
- 12. The method according to claim 11, further comprising generating an alarm when the count of the number of particles having particle diameters greater than the reference particle diameter exceeds the allowable maximum limit number of particles.
- 13. The method according to claim 12, further comprising suspending further operation when said alarm is generated.
- 14. The method according to claim 12, further comprising setting the at least a first nozzle at the home position when the alarm is generated.
- 15. The method according to claim 12, wherein when the alarm is generated, setting the at least a first nozzle at the home position and moving another nozzle from the home position with the steps (c)-(f) being then performed relative to said another nozzle which has a different supply passage supplied with a different resist solution to be coated.
- 16. The method according to claim 11, further comprising selecting any one of four nozzles having respective different supply passages that are respectively supplied with a different resist solution as said at least a first nozzle.
- 17. The method according to claim 11, wherein step (d) is performed at regular intervals of time or each time after a particular event occurs.
- 18. The method according to claim 11, wherein step (e) is carried out after prior steps (c) and (d) are repeated a plurality of times.
- 19. The method according to claim 11, wherein the reference particle diameter is determined to be 0.25 μm.
- 20. The method according to claim 11, wherein step (c) includes discharging the receptacle sample from the at least a first nozzle when the at least a first nozzle is located over the receptacle at a position spaced from and not directly above the substrate.
- 21. The method according to claim 11, wherein said steps (c) and (d) are performed every time just before discharge of the resist solution from the at least a first nozzle on to the substrate.
- 22. The method according to claim 11, wherein step (c) includes discharging the receptacle sample from the at least a first nozzle into the receptacle which is positioned between the home position and the resist coating position and further comprising a step of applying a cleaning liquid to remove any residual resist solution from the receptacle after performing step (d) to prepare the receptacle for receiving the next receptacle sample.
Priority Claims (2)
Number |
Date |
Country |
Kind |
8-252317 |
Sep 1996 |
JP |
|
9-017761 |
Jan 1997 |
JP |
|
Parent Case Info
This application is a Division of application Ser. No. 08/915,737 filed on Aug. 21, 1997, now U.S. Pat. No. 5,938,847.
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