Claims
- 1. A method of applying a coating of photoresist to a circular semiconductor wafer, the wafer having a top surface, a center, and an outer edge, the method comprising extruding a ribbon of photoresist, the ribbon having a width, the ribbon extruded in a spiral pattern which covers the entire top surface of the wafer.
- 2. A method according to claim 1, wherein the ribbon of photoresist is extruded in a spiral pattern beginning at the outer edge of the wafer and ending at the center of the wafer.
- 3. A method according to claim 1, wherein the ribbon of photoresist is extruded in a spiral pattern beginning at the center of the wafer and ending at the outer edge of the wafer.
- 4. A method according to claim 1, wherein the width of the photoresist ribbon is between about one tenth and about one third of the diameter of the semiconductor wafer.
- 5. A method of applying a coating of photoresist to a circular semiconductor wafer, the wafer having a top surface, a center, a diameter, and an outer edge, the method comprising the steps of
(a) mounting the wafer on a chuck, the top surface of the wafer aligned horizontally and oriented upward, (b) positioning an extrusion head adjacent to the outer edge of the wafer and above the top surface of the wafer, the extrusion head configured to extrude photoresist out an extrusion slot, the extrusion slot having a length bounded by a first end and a second end, the extrusion head positioned with the extrusion slot aligned radially with respect to the wafer, the first end of the extrusion slot located adjacent to the outer edge of the wafer, and the second end of the extrusion slot outside the outer edge of the wafer, (c) rotating the wafer about its center, (c) extruding a ribbon of photoresist from the extrusion slot, the ribbon having a width which is substantially equal to the length of the slot, and (e) while extruding photoresist from the extrusion slot, and maintaining the extrusion slot aligned radially with respect to the wafer, moving the extrusion head radially inward from the outer edge of the wafer toward the center of the wafer until the photoresist covers the entire top surface of the wafer.
- 6. A method according to claim 5, wherein the length of the extrusion slot is between about one tenth and about one third of the diameter of the semiconductor wafer.
- 7. A method according to claim 5, wherein the photoresist is extruded from the extrusion slot at a rate which is a constant extrusion rate.
- 8. A method according to claim 5, wherein, with the wafer rotating at a rotational speed, and the extrusion head moving at a radial speed, the motion of the radially moving extrusion head with respect to the rotating wafer is at a tangential velocity which is a constant tangential velocity.
- 9. A method according to claim 5, wherein step (e) comprises maintaining the extrusion slot a predetermined distance above the top surface of the wafer.
- 10. A method according to claim 9, wherein step (e) comprises determining the distance between the extrusion slot and the top surface of the wafer, and adjusting the position of the extrusion slot to maintain the predetermined distance.
- 11. A method according to claim 10, wherein step (e) comprises determining the distance between the extrusion slot and the top surface of the wafer using an optical sensor.
- 12. A method according to claim 5, wherein the photoresist ribbon is extruded in a spiral pattern which covers the entire top surface of the wafer.
- 13. A method according to claim 5, comprising the steps of
(f) removing the extrusion head, and (g) rotating the wafer at high speed.
- 14. A method of applying a coating of photoresist to a circular semiconductor wafer, the wafer having a top surface, a center, a diameter, and an outer edge, the method comprising the steps of
a. mounting the wafer on a chuck, b. positioning an extrusion head at the center of the wafer and above the top surface of the wafer, the extrusion head configured to extrude photoresist out an extrusion slot, the extrusion slot having a length bounded by a first end and a second end, the extrusion head positioned with the extrusion slot aligned radially with respect to the wafer, the first end of the extrusion slot located at the center of the wafer and the second end of the extrusion slot located between the center of the wafer and the outer edge of the wafer, c, rotating the wafer about its center, d. extruding a ribbon of photoresist from the extrusion slot, the ribbon having a width substantially equal to the length of the slot, and e. while extruding photoresist from the extrusion slot, and maintaining the extrusion slot aligned radially with respect to the wafer, moving the extrusion head radially outward toward the outer edge of the wafer until the photoresist covers the entire top surface of the wafer.
- 15. An apparatus for applying a coating of photoresist to a circular semiconductor wafer, the wafer having a top surface, a center, a diameter, and an outer edge, the apparatus comprising
means for mounting a wafer with the top surface of the wafer aligned horizontally and oriented upward, an extrusion head positioned adjacent to the outer edge of the wafer and above the top surface of the wafer, the extrusion head configured to extrude photoresist out an extrusion slot, the extrusion slot having a length bounded by a first end and a second end, the extrusion head positioned with the extrusion slot aligned radially with respect to the wafer, the first end of the extrusion slot located adjacent to the outer edge of the wafer, and the second end of the extrusion slot outside the outer edge of the wafer, means for rotating the wafer about its center, means for extruding a ribbon of photoresist from the extrusion slot, the ribbon having a width substantially equal to the length of the slot, and means for, while extruding photoresist from the extrusion slot, and maintaining the extrusion slot aligned radially with respect to the wafer, moving the extrusion head radially inward toward the center of the wafer until the photoresist covers the entire top surface of the wafer.
- 16. An apparatus according to claim 15, comprising means for rotating a wafer at a rotational speed, and moving the extrusion head at a radial speed, such that the motion of the radially moving extrusion head with respect to the rotating wafer is at a tangential velocity which is a constant tangential velocity.
- 17. An apparatus according to claim 15, comprising means for maintaining the extrusion slot a predetermined distance above the top surface of the wafer.
- 18. An apparatus according to claim 17, wherein the means for maintaining the extrusion slot a predetermined distance above the top surface of the wafer comprises means for determining the distance between the extrusion slot and the top surface of the wafer, and means for adjusting the position of the extrusion slot to maintain the predetermined distance.
- 19. An apparatus according to claim 18, wherein the means for measuring the distance between the extrusion slot and the top surface of the wafer comprises an optical sensor.
- 20. An apparatus according to claim 15, comprising means for extruding a ribbon of photoresist in a spiral pattern beginning at the center of the wafer and ending at the outer edge of the wafer.
- 21. An apparatus according to claim 15, wherein the width of the extrusion slot is between about one tenth and about one third of the diameter of the semiconductor wafer.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from our copending provisional U.S. patent applications 60/050,017, filed Jun. 16, 1997; 60/050,159, filed Jun. 19, 1997; and 60/055,789, filed Aug. 14, 1997.
Provisional Applications (3)
|
Number |
Date |
Country |
|
60050017 |
Jun 1997 |
US |
|
60050159 |
Jun 1997 |
US |
|
60055789 |
Aug 1997 |
US |
Continuations (1)
|
Number |
Date |
Country |
Parent |
09094443 |
Jun 1998 |
US |
Child |
09745611 |
Dec 2000 |
US |